한국전기전자재료학회:학술대회논문집 (Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference) (Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference)
한국전기전자재료학회 (The Korean Institute of Electrical and Electronic Material Engineers)
- 연간
- 한국전기전자재료학회 2004년도 추계학술대회 논문집
- 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
- 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
- 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
- 한국전기전자재료학회 2004년도 춘계학술대회 논문집
- 한국전기전자재료학회 2004년도 춘계학술대회 논문집 방전 플라즈마 유기절연재료 초전도 자성체연구회
- 한국전기전자재료학회 2004년도 춘계학술대회 논문집 디스플레이 광소자분야
- 한국전기전자재료학회 2004년도 제6회 학술대회 논문집 일렉트렛트 및 응용기술연구회
- 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
- 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
- 한국전기전자재료학회 2003년도 제5회 영호남 학술대회 논문집
- 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
- 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
- 한국전기전자재료학회 2003년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마연구회
- 한국전기전자재료학회 2003년도 제5회 학술대회 논문집 일렉트렛트 및 응용기술연구회
- 한국전기전자재료학회 2003년도 춘계학술대회 논문집 초전도 자성체 연구회
- 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
- 한국전기전자재료학회 2003년도 춘계학술대회 논문집 기술교육전문연구회
- 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
- 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
- 한국전기전자재료학회 2002년도 제4회 영호남학술대회 논문집
- 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
- 한국전기전자재료학회 2002년도 하계학술대회 논문집
- 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
- 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
- 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
- 한국전기전자재료학회 2002년도 춘계학술대회 논문집 디스플레이 광소자 분야
- 한국전기전자재료학회 2002년도 춘계학술대회 논문집 초전도 자성체
한국전기전자재료학회 2001년도 하계학술대회 논문집
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Distribution Automation System (DAS) has been designed and implemented for feeder automation using the Paircable, Optical-Fiber, Wireless, TRS as a communication media. KEPCO has been constructed DAS since 1984. We have two types of DAS. one is large-scale DAS for major city in korea, the other is small-scale DAS (or the rest of major city. we are plan to finish small-scale DAS by end of 2001.
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Perdeuterated hexaflouroacetylacetonato-ytterbium [Yb(SOL)-D)
$_3$ ] complexes were synthesized by the keto-enol tautomerism reaction of Yb(SOL-H)$_3$ in methanol-d$_4$ in methanol-d$_4$ in order to reduce the radiationless transition to the ligands. The luminescence properties of Yb(SOL-D)$_3$ complex were measured in the following anhydrous deuterated organic solvents ; Methanol-d$_4$ , THF-d$\sub$ 8/, PO(OCH$_3$ )$_3$ and DMSO-d$\sub$ 6/. The intensity, lifetime and quantum efficiency of the luminescence in DMSO-d$\sub$ 6/ were superior to those in other deuterated solvents. It was suggested that the anhydrous DMSO-d$\sub$ 6/ might be the most appropriate solvent for the liquid laser material of Yb(SOL-D)$_3$ complex. -
물(수력)은 환경친화적이며 고갈되지 않는 재생에너지이고 잠재력과 활용성이 높은 대체에너지입니다. 레네테크는 독일의 전문기술진이 연구개발한 특허 출원된 3가지 핵심기술을 결합하여 그간 문제가 된 대체에너지의 경제성가지도 충족시키는 새로운 개념의 저비용 고효율의 수(조)력 발전기를 탄생 시켰습니다.
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Recently, STI(Shallow Trench Isolation) process has attracted attention for high density of semiconductor device as a essential isolation technology. Without applying the conventional complex reverse moat process, CMP(Chemical Mechanical Polishing) has established the Process simplification. However, STI-CMP process have various defects such as nitride residue, torn oxide defect, damage of silicon active region, etc. To solve this problem, in this paper, we discussed to determine the control limit of process, which can entirely remove oxide on nitride from the moat area of high density as reducing the damage of moat area and minimizing dishing effect in the large field area. We, also, evaluated the reliability and reproducibility of STI-CMP process through the optimal process conditions.
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Hydrogen passivation of Si nanocrystals identifies luminescence mechanism indirectly. Si nanocrystallites thin films on p-type (100) Si substrate have been fabricated by pulsed laser deposition technique using a Nd:YAG laser After deposition, Si nanocrystallites thin films have been annealed at 600
$^{\circ}C$ and 760$^{\circ}C$ in nitrogen ambient, respectively. Hydrogen passivation was subsequently performed at 500$^{\circ}C$ in forming gas (95 % N$_2$ + 5 % H$_2$ ) for an 1 hour. We report the photoluminescnece(PL) property of Si thin films by the hydrogen passivation. The luminescence mechanism of Si nanocrystallites has also been investigated. -
Chemical mechanical polishing(CMP) process has been widely used to planarize dielectric layers, which can be applied to the integrated circuits for deep sub-micron technology. The rise throughput and the stability in the device fabrication can be obtained by applying of CMP process to STI structure in 0.18
$\mu\textrm{m}$ m semiconductor device. The reverse moat process has been added to employ in of each thin films in STI-CMP was not equal, hence the devices must to be effected, that is, the damage was occurred in the device area for the case of excessive CMP process and the nitride film was remained on the device area for the case of insufficient CMP process, and than, these defects affect the device characteristics. Also, we studied the High Selectivity Slurry(HSS) to perform global planarization without reverse moat step. -
This paper presents the modeling methodology of Zinc diffusion process applied for high-speed avalanche photodiode fabrication using neural networks. Three process factors (sealing pressure, amount of Zn
$_3$ P$_2$ source per volume, and doping concentration of diffused layer) are examined by means of D-optimal design experiment. Then, diffusion rate and doping concentration of Zinc in diffused layer are characterized by a static response model generated by training fred-forward error back-propagation neural networks. It is observed that the process models developed here exhibit good agreement with experimental results. -
In this paper, we explain briefly polysilicon guard layer in a simple 3-D structure. Simulation was performed extensively to see interference and characterize the role of the polysilicon guard layer. Especially, we performed extensively S-parameter simulation to analysis the signal interference. The interference was characterized in terms of oxide thickness, polysilicon doping concentration, thickness, number of contact of polysilicon guard, and metal guard size.
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We have investigated physical and electrical properties of the Hf
$O_2$ /HfS$i_{x}$ /$O_{y}$ thin film for alternative gate dielectrics in the metal-oxide-semiconductor device. The oxidation of Hf deposited directly on the Si substrate results in the H$f_{x}$ /$O_{y}$ interfacial layer and the high-k Hf$O_2$ film simultaneously. Interestingly, the post-oxidation N2 annealing of the H102/H1Si70y thin films reduces(increases) the thickness of an amorphous HfS$i_{x}$ /$O_{y}$ layer(Hf$O_2$ layer). This phenomenon causes the increase of the effective dielectric constant, while maintaining the excellent interfacial properties. The hysteresis window in C-V curves and the midgap interface state density($D_{itm}$ ) of Hf$O_2$ /HfS$i_{x}$ /$O_{y}$ thin films less than 10 mV and ~3$\times$ 10$^{11}$ c$m^{-2}$ -eV without post-metallization annealing, respectively. The leakage current was also low (1$\times$ 10-s A/c$m^2$ at$V_{g}$ = +2 V). It is believed that these excellent results were obtained due to existence of the amorphous HfS$i_{x}$ /$O_{y}$ buffer layer. We also investigated the charge trapping characteristics using Fowler-Nordheim electron injection: We found that the degradation of Hf$O_2$ /HfS$i_{x}$ /$O_{y}$ gate oxides is more severe when electrons were injected from the gate electrode.e electrode.e.e electrode.e. -
In this study, gate leakage current mechanism has been analyzed for GaAs MESFET with different temperatures ranging from 27
$^{\circ}C$ to 300$^{\circ}C$ . It is expected that the thermionic and field emission at the MS contact will dominate the current flow. Thermal cycle is applied to test the reliability of the device. From the results, it is proved that thermal stress gradually increases the gate leakage current at the same bias conditions and leads to the breakdown and failure mechanism which is critical in the field equipment. Finally the gate contact under the repeated thermal shock has been tested to check the quality of Schottky barrier and the current will be expressed in the analytical from to associate with the electrical characteristics of the device. -
We studied the characteristics of polishing pad, which can apply STI-CMP process for global planarization of multilevel interconnection structure. Also, we investigated the effects of different sets of polishing pad, such as soft and hard pad. As an experimental result, hard pad showed center-fast type, and soft pad showed edge-fast type. Totally, the defect level has shown little difference, however, the counts of scratch was defected less than 2 on JRlll pad. Through the above results, we can select optimum polishing pad, so we can expect the improvements of throughput and devise yield.
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Metal-insulator-semiconductor (MIS) C-V properties with high dielectric AIN thin films showed no hysteresis and good interface properties. The dielectric constant of the AIN film calculated from the capacitance at the accumulation region in the capacitance-voltage(C-V) characteristics was about 8. The C-V characteristics of MFIS capacitor showed a hysteresis loop due to the ferroelectric nature of the LiNbO
$_3$ thin films. Typical dielectric constant value of LiNbO$_3$ film of MFIS device was about 23. The memory window width was about 1.2V at the gate voltage of$\pm$ 5 V ranges. Typical gate leakage current density of the MFIS structure was the order of 10$^{-9}$ A/cm$^2$ at the range of within$\pm$ 500 kV/cm. The ferroelectric capacitors showed no polarization degradation up to about 10$^{11}$ switching cycles when subjected to symmetric bipolar voltage pulse(peak-to-peak 8V, 50% duty cycle) in the 500kHz. -
$SrBi_2Ta_2O_{9}$ thin films were etched in inductively coupled$Cl_{2}$ /$CF_{4}$ /Ar plasma. The maximum etch rate was 1060$\AA\textrm{m}$ /min in$Cl_{2}$ /$CF_{4}$ /Ar (80). The chemical reactions on the etched surface were studied with x-ray photoelectron spectroscopy. The etching of SBT thin films in$Cl_{2}$ /$CF_{4}$ /Ar were etched by chemically assisted reactive ion etching. The small addition of$Cl_2$ into$CF_4$ (20)/Ar(80) plasma will decrease the fluorine radicals and the increase Cl radical. -
Effect of
$N_2$ flow rate on properties of GaN thin films grown by plasma-enhanced molecular beam epitaxy(PEMBE) was discussed to optimize the quality of thin films. It was found that at low$N_2$ flow rate indicating high III/V flux ratio, the growth rate of GaN thin films was controlled by$N_2$ flux, and at high$N_2$ flow rate the growth rate was not controlled by$N_2$ flux any longer. It was also found that III/V flux ratio affected film quality. The film grown at higher$N_2$ flow rate showed low background carrier concentration, higher carrier mobility, and narrow FWHM in band-edge emission of low temperature PL. It is thought that the film in more Ga flux region was grown by 2-dimensional layer-by-layer growth mode, and the film in more nitrogen region was grown by 3-D island growth mode. All samples exhibited a good crystallinity. -
MFIS(Metal-ferroelectric-insulator- semiconductor) structures using silicon oxynitride(SiON) buffer layers were fabricatied and demonstrated nonvolatile memory operations. Oxynitride(SiON) films have been formed on p-Si(100) by RTP(rapid thermal process) in O
$_2$ +N$_2$ ambient at 1100$^{\circ}C$ . The gate leakage current density of Al/SiON/Si(100) capacitor was about the order of 10$\^$ -8/ A/cm$^2$ at the range of${\pm}$ 2.5 MV/cm. The C-V characteristics of Al/LiNbO$_3$ /SiON/Si(100) capacitor showed a hysteresis loop due to the ferroelectric nature of the LiNbO$_3$ thin films. Typical dielectric constant value of LiNbO$_3$ film of MFIS device was about 24. The memory window width was about 1.2V at the electric field of${\pm}$ 300 kV/cm ranges. -
In order to investigate the effect of salinity level on tracking characteristics of polymer insulators for distribution power systems, tracking tests were performed by tracking wheel tester under different salt concentration. In this study, 6 kinds of polymer insulators were tested under 2200
${\mu}\textrm{s}$ /cm and 4000${\mu}\textrm{s}$ /cm salinity. The salinity level has a significant effect on the tracking characteristics. Namely, most polymer insulators showed the good tracking resistance in case of low salinity level. But, in case of high salinity level some polymer insulators showed the excessive erosion and tracking. These phenomena may come from the different aging mechanism. It can be concluded that too high salinity level is not desirable in aging test of polymer insulators. -
In this work, the surface of inorganic fillers were modified with some functional groups such as stearic acid, aliphatic long chain, vinylsilane and aminosilane to control the interaction between inorganic fillers and polymer matrix. Ethylene-vinyl acetate copolymers (EVA) with various amount of vinyl-acetate content and copolyether-ester elastomer were used as polymer matrix. The addition of inorganic fillers increases flame retardancy, but results in steep drop of electrical and mechanical properties, which may be caused by the defect in the interface between organic/inorganic hybrid composites. The hybrid composites are found to show better mechanical properties and higher volume resistivities as inorganic fillers are well dispersed and have good adhesion with polymer matrix. Also, the most effective type of functional group coated on fillers depends on the chemical structure of polymer.
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Space charge formation at high temperature was investigated in several polymers using pulsed electro-acoustic (PEA) method. In SXLPE, homocharge is found and increased as an increase of temperature. In a charge of polarity of poling voltage(positive to negative), space charge mainly cause of hole injection. In Ionomer, heterocharge is found because of ion. As an increase of temperature heterocharge is also increased. In PET, As an increase of temperature homocharge is decreased.
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Our knowledge about their long-term performance in an outdoor environment is still very limited. The electrical stress caused the surface of these insulators to become degradation. In order to evaluate leakage current patterns caused by surface aging on polymeric insulators, we utilized the combined aging test facility and leakage current monitoring system. And we get the continuous leakage current values from each sample. After completing the 3000h combined aging cycle test, leakage current measurement were conducted for these samples and carried out harmonics analysis for its data.
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The dielectric breakdown of epoxy composites used for transformers was experimented and then its data were simulated by Weibull distribution probability. First of all, speaking of dielectric breakdown properties, the more hardener increased the stronger breakdown strength at low temperature because of cross-linked density by the virtue of ester radical. The breakdown strength of specimens with filler was lower than it of non-filler specimens because it is believed that the adding filler forms interface and charge is accumulated in it, therefore the molecular motility is raised and the electric field is concentrated. In the case of filled specimens with treating silane, the breakdown strength become much higher Finally, from the analysis of weibull distribution, it was confirmed that as the allowed breakdown probability was given by 0.1[%], the applied field value needed to be under 21.5 [Mv/cm].
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The formation of soft magnets on paper(SMOP) is proposed for the first time and we have demonstrated it successfully. Iorn was used to form the soft magnet thin film on paper. And Cr layer was used as a buffer layer because the roughness of substrate(paper) is not negligible. The maximum magnetization of Cr/Fe/Cr/Paper(Fe:5000
${\AA}$ ) is about 1000 [emu/cc] and the coercive field is about 80 [Oe.]. It is necessary to reduce the coercivity and to enlarge the magnetization value of SMOP to perform a good soft magnetic characteristics on paper. On, the permalloy material is the proper candidate for its high permeability, low coercivity and high magnetization values. -
In order to investigate the magnetic properties of CoCr-based bilayered thin films on kind of underlayer, we introduced amorphous Si layer to Co-Cr(-Ta) magnetic layer as underlayer. With the thickness of CoCr, CoCrTa single layer, crystalline orientation and perpendicular coercivity was improved. It was revealed that by introducing the Si underlayer, the c-axis orientation of CoCr, CoCrTa magnetic layer was improved largely. However, with increasing Si film thickness, perpendicular coercivity and saturation magnetization of Cocr/si, CoCrTa/Si bilayered thin films was decreased. Grain size of bilayered thin films became larger.
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In order to investigate the effect of Ge addition to the Cu matrix on the microstructure and the critical current density, four kinds of internal tin processed Nb
$_3$ Sn strands with pure Cu and Cu 0.2, 0.4, 0.6 wt % Ge alloys were drawn to 0.8 mm diameter. The microstructure and critical current of internal tin processed Nb$_3$ Sn wires that were heat treated at temperatures ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$ for 240h were investigated. The Ge addition to the matrix did not make workability worse. A Ge rich layer in the Cu-Ge matrix suppressed the growth of the Nb$_3$ Sn layer and promoted grain coarsening. The greater the Ge content in the matrix, the lower the net Jc result after Nb$_3$ sn reaction heat treatment. There was no significant variation in Jc observed with heat treatment temperature ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$ . The values of AC loss of Ge added wires were decreased to 40 % compare with no addition wire. Low AC loss was due to segregation of Ge rich layer in the Cu-Ge matrix. If Ge added wire with thin Nb filaments were fabricated, slow diffusion rate of Sn would be overcome and decreased AC loss that is weak Point of internal tin method. -
YBCO HTS thick films coated using powder, Y
$_2$ O$_3$ +L, quenched over 1200$^{\circ}C$ was studied. Quenched powder was crushed and mixed well in order to obtain uniformly dispersed Y2ll. Also, the powder was prepared with various condition in other to acquire optimum micro structure. As a result, it was found that the quenched sample on 1300$^{\circ}C$ , holding time of 30min, has a bettor characteristic than other sample. On the other hand, the effect of film thickness was investigated. We concluded that the initiate film thickness has to be over 150$\mu\textrm{m}$ . Especially, it was found that the film coated over 3 times with 50$\mu\textrm{m}$ m was best quality. -
The magnetic suspension of a high T
$\sub$ c/ BipbSrCaCuO superconductor beneath toroial Permanent magnet was examined by means of an improved magneto-balancing method at 77K. Both the experimental values of the suspending position and the force exerted upon the superconducting specimen were in good agreement with those calculated from the magnetization curve of the specimen and the magnetic field map of the used permanent magnet. -
High-temperature superconductor films of YBa
$_2$ Cu$_3$ $O_{7-x}$ were fabricated by electrophoretic deposition (EPD) from alcohol-based suspension. Maximum stability is observed for the suspension containing iso-alcohol as the dispersion medium. However, for the formation of a dense and adherent coating of YBCO on a silver substrate by EPD, the best results were obtained in mix PrOH and BuOH suspension. The superconducting critical current density (J$_{c}$ ) was 1200 A/cm$^2$ for a films deposited in 30% iso-PrOH and 70 % iso-BuOH suspension.ion. -
ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique at the oxygen pressure of 350 mTorr. In order to investigate the effect of post-annealing treatment with oxygenn pressure of 350 mTorr on the optical property of ZnO thin films, films have been annealed at various substrate temperatures after deposition. After post-annealing treatment in the oxygen ambient, the optical properties of the ZnO thin films were characterized by PL(Photoluminescence) and structural properties of the ZnO were characterized by XRD, and have investigated structural property and optical property for application of light emission device.
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Multiwalled carbon nanotubes were massively produced by the catalytic reaction of C
$_2$ H$_2$ - Fe(CO)$\sub$ 5/ mixture at 750 - 950$^{\circ}C$ in a quartz tube reactor and over quartz substrates. Well-aligned MWNT array grows perpendicular to the quartz tube reactor and the quartz substrates at an average of 60 nm in diameter and up to several thousands of micrometers in length. This method does not require any pretreatment of substrates and CNTs are grown at atmospheric pressure. It could be suitable for mass production of multiwalled nanotubes. Scanning electron microscope and transmission electron microscope images of the nanotubes deposited on the substrates allowed us to monitor the quality of MWNTs grown under different operating conditions. -
Si thin films on p-type (100) Si substrate have been fabricated by pulsed laser deposition technique using a Nd:YAG laser. The pressure of the environmental gas during deposition was 1 Torr. After deposition, Si thin film has been annealed again at 400-840
$^{\circ}C$ in nitrogen ambient. Strong blue photoluminescence (PL) have been observed at room temperature. We report the PL properties of Si thin films depending on the variation of the annealing temperature. -
Vertically aligned carbon nanotubes are grown on iron-deposited silicon oxide substrates by thermal chemical vapor deposition of acetylene gas at the temperature range 750∼950
$^{\circ}C$ . As the growth temperature increases from 750 to 950$^{\circ}C$ , the growth rate increases by 4 times and the average diameter also increases from 30 nm to 130 nm while the density increases progresively with the growth temperature and a higher degree of crystalline perfection can be achieved at 950$^{\circ}C$ . This result demonstrates that the growth rate, diameter, density, and crystallinity of carbon nanotubes can be controlled with the growth temperature. -
We report the structural ,optical and electrical properties of ZnO thin films depending on the variation of the film thickness. The properties of the films deposited on sapphire (001) substrates using a pulsed laser deposition technique (PLD) were characterized with XRD, hall measurement and photoluminescence (PL). In our study, the increase of the thickness of ZnO thin films shows the improvement of the structural and optical properties. The electric properties of the films were also well matched with the structural and optical properties
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As microeletronics technology continues to progress, there is also a continuous demand on highly integration and miniaturization of systems. For example, it is desirable to package several integrated circuits together in multilayer structure, such as multichip modules, to achieve higher levels of compactness and higher performance. Passive components (i.e., capacitors, resistors, and inductors) are very important for many MCM applications. In addition, the low-temperature co-fired ceramic (LTCC) process has considerable potential for embedding passive components in a small area at a low cost. In this paper, we investigate a method of statistically modeling integrated passive devices from just a small number of test structures. A set of LTCC inductors is fabricated and their scattering parameters (5-parameters) are measured for a range of frequencies from 50MHz to 5GHz. An accurate model for each test structure is obtained by using a building block based modeling methodology and circuit parameter optimization using the HSPICE circuit simulator.
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PbWO
$_4$ can be densified at 85$0^{\circ}C$ and it shows fairy good microwave dielectric properties; dielectric constant($\varepsilon$ $_{r}$ ) of 21.5, quality factor(Q$\times$ f$_{0}$ ) of 37,224 GHz, and temperature coefficient of resonant frequency($\tau$ /suf f/) of -31ppm/$^{\circ}C$ . Due to its low sintering temperature, PbWO$_4$ can be used as a multilayered chip component at microwave frequency with high electrical performance by using high conductive electrode metals such as Ag and Cu. However, in order to use this material for microwave communication devices, the$\tau$ $_{f}$ of PbWO$_4$ must be stabilized to near zero with high Q$\times$ f$_{0}$ . In present study, PbWO$_4$ was modified by adding TiO$_2$ , B$_2$ O$_3$ , and CuO in order to improve the microwave dielectric properties without increasing the sintering temperature. The addition of TiO$_2$ increased the$\tau$ $_{f}$ and$\varepsilon$ $_{r}$ , due to its high rr(200ppm/$^{\circ}C$ ) and$\varepsilon$ $_{r}$ (100). However, the addition of TiO$_2$ reduced the Q$\times$ f$_{0}$ value. When the mot ratio of PbWO$_4$ and TiO$_2$ was 0.913:7.087, near zero$\tau$ $_{f}$ (0.2ppm/$^{\circ}C$ ) was obtaibed with$\varepsilon$ $_{r}$ =22.3, and Q$\times$ f/$_{0}$ =21,443GHz. With this composition, various amount of B$_2$ O$_3$ and CuO were added in order to improve the quality factor. The addition, of B$_2$ O$_3$ decreased the$\varepsilon$ $_{r}$ . However, increased Q$\times$ f$_{0}$ and$\tau$ $_{f}$ . When 2.5 wt% of B$_2$ O$_3$ was added to the 0.913PbWO$_4$ -0.087TiO$_2$ ceramic,$\tau$ $_{f}$ =8.2,$\varepsilon$ $_{r}$ =20.3, Q$\times$ f$_{0}$ =54784 GHz. When CuO added to the 0.913PbWO$_4$ -0.087TiO$_2$ ceramic,$\tau$ $_{f}$ was continuously decreased. And$\varepsilon$ $_{r}$ . and Q$\times$ f$_{0}$ were increased up to 1.0 wt% then decreased. At 0.1 wt% of CuO addition, the 0.913PbWO$_4$ -7.087Ti0$_2$ Ceramic Showed$\varepsilon$ $_{r}$ =23.5,$\tau$ $_{f}$ =4.4ppm/$^{\circ}C$ , and Q$\times$ f$_{0}$ =32,932 GHz.> 0/=32,932 GHz.X>=32,932 GHz.> 0/=32,932 GHz. -
A great deal of attention has been focused on the application of miniaturized piezoelectric transformers to the low power source for the microsystem. The dielectric and piezoelectric properties of Pb(Mn,W,Sb,Nb)O
$_3$ -Pb(Zr,Ti)O$_3$ ceramics have been investigated on different calcination(750$^{\circ}C$ ∼950$^{\circ}C$ ) and sintering(1100$^{\circ}C$ ∼1300$^{\circ}C$ ) temperatures. The perovskitic phase was formed by the solid phase reaction of the oxides. Anisotropic (k$\sub$ t/k$\sub$ p/) properties of electromechanical coupling coefficient and piezoelectric coefficient have been proven to be depending on processing temperatures. The value of electromechanical coupling factor of K$\sub$ p/>0.51 and a mechanical quality factor of Q$\sub$ m/>2000 were obtained. The piezoelectric transformer was prepared using this ceramics with the composition of Pb(Mn,W,Sb,Nb)O$_3$ -Pb(Zr,Ti)O$_3$ We studied the influence of different processing temperature on the microstructure and piezoelectric properties of complex PZT-based ceramics. and the characteristic of piezoelectric transformer. -
(Ba
$_{0.6-x}$ Sr$_{0.4}$ Ca$_{x}$ )TiO$_3$ (x=0.10, 0.15, 0.20) ceramics were fabricated by the mixed-oxide method and their dielectric properties were investigated with variation of composition ratio, doped ZrO$_2$ (0.5, 1.0, 1.5, 2.0, 3.0 wt%) and sintered at 145$0^{\circ}C$ . The dielectric constant and loss of the x=0.10 specimen applied field were 19.86 and 0.302 % at 0 V/cm, and 25.937 and 0.339 % at 300 V/cm, respectively. Dielectric constant were increased with increased applied field and decreased with increased frequency, and dielectric loss were within 0.1% at applied 800 MHz, respectively. all specimens showed fairly good applied field. Although, dielectric constant and loss of all specimen showed to tend of nearly the same. same. -
Three sets of ZnO ceramic devices (reference samples with Matsuoka\`s composition; added 7o MgO, A1
$_2$ O$_3$ , SiO$_2$ ) have been prepared by the conventional mixed oxide route. These additives were determined by the factors of valences and ionic radiuses. DC accelerated degradation test was performed for analysis of degradation characteristics versus the various additives. The conditions of DC degradation test were 115${\pm}$ 2$^{\circ}C$ for 12h. Using XRD and SEM, the Phase and microstructure of samples were analyzed respectively. E-J analysis was used to determine${\alpha}$ . Frequency analysis was accomplished to understand the relationship between R$\sub$ g/ and$R_{b}$ with the electric stress at the equivalent circuit. -
In this paper, we investigated the dielectric and piezoelectric properties of Pb(Sb, Nb)O
$_3$ -Pb(Zr, Ti)O$_3$ ceramic(PSN) for piezoelectric transformer and actuator etc. Effect of MnO$_2$ addition on the PSN ceramic was investigated. Anisotropic properties of electromechanical coupling factor and piezoelectric properties proved to be varied with amount of MnO$_2$ impurity and sintering temperature. The electromechanical coupling factor k$_{p}$ of 0.38 and the mechanical quality factor Q$_{m}$ of 1944 were obtained from the specimen with 0.4 wt% MnO$_2$ sintered at 115$0^{\circ}C$ addition. Experimental results indicated that the PSN ceramic with MnO$_2$ impurity can be effectively used for piezoelectric transformer and actuator.tor. -
Carbon nitride films were grown on Si (100) substrate by a laser-electric discharge method with and without a magnetic field assistance. The magnetic field leads to vapor plume plasma expending upon the ambient arc discharge plasma area. Influence of the magnetic field has resulted in increase of a crystallite size in the films due to bombardment (heating) of Si substrates by energetic carbon and nitrogen species generated during cyclotron motion of electrons in the discharge zone. Many crystalline grains were observed in the morphology of the deposited films by scanning electron microscopy. In order to determine the structural crystalline parameters, X-ray diffraction (XRD) was used to analysis the grown films.
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Thin films of phase-pure perovskite (P
$b_{0.72}$ L$a_{0.28}$ )$Ti_{0.93}$ $O_3$ (PLT) were deposited in-situ onto Pt/Ti/$SiO_2$ /Si substrates by pulsed laser deposition. We have systematically investigated the variation of grain sizes depending on the process condition. Both in-situ annealing and ex-situ annealing treatments have been compared depending on the annealing time. Two-step process to grow (P$b_{0.72}$ L$a_{0.28}$ )$Ti_{0.93}$ $O_3$ (PLT) films was adopted and verified to be useful to enlarge the grain size of the film and to enhance the leakage current characteristics. The grain sizes of PLT thin films were successfully controlled 260 to 350 nm by changing process parameters. Electrical properties including dielectric constant, ferroelectric characteristics, crystallization and leakage current of PLT thin films were shown to be strongly inf1uenced by grain size. Also PLT thin films on p-type(100) Si substrate will be fabricated by pulsed laser deposition technique using a Nd:YAG laser with different wavelengths of 355, 532 and 1064 nm. Effect of the variation of laser wavelength on dielectric properties will be discussed. Microstructural and electrical properties of the film were investigated by C-V measurement leakage current measurement and SEM.ent and SEM. -
We have seen the effects of buffer layer in organic light-emitting diodes using poly(N-vinylcarbazole)(PVK). Polymer PVK buffer layer was made using spin casting techniques. Two different types of spin casting have been applied; static coating and dynamic coating. Two device structures were fabricated; one is ITO/TPD/Alq
$_3$ /Al as a reference, and the other is ITO/PVK/TPD/Alq$_3$ /Al to see the effects of buffer layer in organic light-emitting diodes. Current-voltage characteristics and luminous efficiency were measured with a variation of spin-casting methods and rpm speeds. We have obtained an improvement of luminous efficiency by a factor of two and half when the PVK buffer layer is used. -
The organic light-emitting devices (OLEDs) based on fluorescence have low efficiencies due to the requirement of spin-symmetry conservation. By using the phosphorescent material, the internal quantum efficiency can reach 100 %, compared to 25 % in the case of the fluorescent material. Thus, the phosphorescent OLEDs have recently been extensively studied and showed higher internal quantum efficiencies then the conventional OLEDs. In this study, we investigated the characteristics of the phosphorescent OLEDs, with the green emitting phosphor, Ir(ppy)
$_3$ (tris(2-phenylpyridine)iridium). The devices with a structure of ITO/TPD/Ir(PPy)$_3$ doped in the host material/BCP/Alq$_3$ /Li:Al/Al were fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of Ir(PPy)$_3$ and the host materials, we fabricated several devices and investigated the device characteristics. -
The functionlized dendrimer containing 48 azobenzene was synthesized. Many isolated featureless domains were explicitly observed even at the air-water interface. Also, these monolayers were representatively observed, showing the change of surface pressure with irradiation time and wavelength. In AFM images. the larger domains irregularly shaped structures on the top while the smaller ones were free from such defects. In the optical absorption spectra of the LB films by UV irradiation and heat treatment, only photoisomerization of the G4-48Az monolayers was observed, a decrease of absorbance peak without change of the spectral shape. This suggests that optical behavior and morphological change are affected by the functional group and the symmetric chain.
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ZnO varistors have been widely used to protect power system and electronic system against overvoltages based on their excellent nonlinearity. In order to increase their protection capability, the fracture and protection technologies of arresters have to study according to their applications, namely ImA DC voltage, leakage currents, impulse residual voltages, withstanding capability to impulse surge, and energy absorption capability. ZnO varistors which have nonlinear current-voltage characteristic name a number of failure mechanism when ZnO elements absorb surge energies. Failure mode by thermal stress and Pin hole are among the most common failure mechanism at the high current surge current. In this study, the fracture mechaism of power arresters are introduced and protection technologies are researched. In particular the effect of thermal stress by surge currents to ZnO elements and methods against arc surge energy through withstand structure design of arrester are discussed.
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Traction motors driven by high speed switching inverters is demanded higher operating temperature, severe duty cycles, higher starting current, frequent voltage transients and finally severe environmental exposure. For applications to inverter duty, traction motors needs a special insulation system, which has characteristics of increased bond strength, lower operating temperature and higher turn-to-turn insulation. In this paper, design considerations and manufacturing procedure of 200 Class insulation system with polyimde(Kapton) main insulation and silicone resin VPI process on the traction motor for EMU will be reviewed. And performance test and long life evaluation test which prove stability and long life evaluation test which prove stability and reliability of insulation system for traction motor will be introduced.
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In this study, contour vibration mode piezoelectric transformer with size of 27.5
${\times}$ 27.5${\times}$ 2.6mm$^3$ using PNW-PMN-PZT ceramic was fabricated. And the piezoelectric transformer was adopted to fluorescent lamp ballast circuit. Electrical characteristics of the piezoelectric transformer were investigated for fluorescent lamp ballast application. The electrical properties and characteristic temperature rise were measured using oscilloscope and infrared temperature sensor. A 28W fluorescent lamp was successfully driven by the fabricated ballast circuit. After driving the lamp using ballast circuit for 24 min, the output power, efficiency and characteristic temperature rise of piezoelectric transformer showed the appropriate values of 28.85[W], 86.3[%] and 15[$^{\circ}C$ ], respectively. -
A 30kw Dual rotor Turbines HAWT/VAWT combined wind turbine system that can drastically enhance the power production capability compared to conventional Single Rotor Turbine HAWT system. The combined system that takes advantage of strong point of both horizontal and vertical Axis wind turbine system developed by a venture firm KOWINTEC of Chonbuk national university. The HAWT/VAWT hybrid system has been successfully field tested and commercial operating since Feb. 12, 2001 in Hae-chang rest park, Bu-an county near the Sae Man-Kum Sea Dike. This paper will briefly describe the field test results performance and a special aerodynamic structure with bevel-planetary gear box of Dual Rotor Wind Turbine system.
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Electrical equipment for railway is always experiencing wear and degradation by mechanical, electrical and environmental stress in service and the fault or the accident of high voltage main circuit directly causes operation interruption. Particularly propulsion drive of high speed switching inverter takes the form of specific degradation mechanism such as fast rising transient surge, reflective overvoltage and harmonic stress, and it is known that it threatens the long life and the reliability of electrical equipment. In this paper, statistics of fault and accident on main electrical equipment for railway are presented and also insulation degradation mechanism, which governs end life of electrical device, is analyzed. Finally the method of fault respondence and reliability improvement on the main electrical equipments will be reviewed in order to prevent operation interruption.
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The undesirable phase transformation of zirconium dioxide at high temperatures can be eliminated by stabilization of the cubic phase with an addition of a selected alkaline earth or rare-earth oxide. In this paper the ionic conductivity of cubic solid solutions in the stabilized ZrO
$_2$ by CaO-Y$_2$ O$_3$ system was examined. The higher ionic conductivity appears to be related to lower activation energy rather than to the number of oxygen vacancies dictated by composition. Those compositions of highest conductivity lie close to the cubic-monoclinic solid-solution phase boundary. Conductivity temperature data are presented that indicate a reversible order-disorder transition for Zr$_2$ 2-Y$_2$ O$_3$ cubic solid solutions containing 20 and 25 mole %$Y_2$ O$_3$ . -
A flame detector responds either to radiant energy visible to the human eye or outside the range of human vision. Such a detector is sensitive to glowing embers, coals, or flames which radiate energy of sufficient intensity and spectral quality to actuate the alarm. An infra-red detectors can respond to the total IR component of the flame alone or in combination with flame flicker in the frequency range of 5 to 30 Hz. A major problem in the use of infrared detectors receiving total IR radiation is the possible interference of solar radiation in the infrared region. When detectors are located in places shielded from the sun, such as vaults. filtering or shielding the unit from the sun's rays is unnecessary. In this study, we proposed method for redue a false alarm with using filtering & sensor technology for distinguish of causes of raise a false alarm and pure flame.
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최근 정전기 방지 및 전자파 차폐재료로 주목받고 있는 전도성 고분자를 절연체 고분자 표면에 코팅하여 정전기 방지 포장용으로 사용되는 투명 대전방지 고분자 쉬트 및 필름을 개발하였다. 현재 사용하고 있는 정전기 방지 포장용 고분자는 폴리스티렌이나 폴리비닐에 카본블랙을 혼합하거나 또는 계면활성제를 표면 에 코팅하여 사용하였다. 그러나 카본블랙을 섞은 경우는 카본입자가 불순물로 작용하여 제품을 오염시키고 검은색 불투명이기 때문에 포장 후 제품을 확인 할 수 없으며 카본 혼합에 따른 기저수지의 물성 약화 가 문제가 되고 있으며 계면활성제를 혼합하거나 코팅하여 사용하는 경우는 시간이 지남에 따라 전도성이 소멸되며 입자가 표면으로 blooming out되어 제품을 오염시키는 단점을 가지고 있다. 본 기술 개발에 의하여 얻어진 투명 전도성 고분자 쉬트 및 필름은 기저수지가 투명할 경우 550nm에서 투명도를 5% 이하로 감소시키며 전도성 물질로 고분자를 사용하기 때문에 영구적인 전도성을 가지며 기저 고분자의 물성을 그 대로 유지 할 수 있는 장점을 가지고 있다. 본 개발품은 전자 부품 및 반도체 포장용 트레이, 캐리어 소재 및 정전기 방지를 필요로 하는 모든 분야에 사용될 수 있으며 전도성 부여 처리기술을 가지고 있기 때문에 포장, 운반 목적 외에 여러 가지 정전기 방지 처리분야에 적용이 가능하다.
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ZnO buffer layers were used to grow ZnO films on c-plane sapphire substrates. The role of ZnO buffer layers in the growth of ZnO thin films on sapphire substrates was investigated by scanning electron microscopy, X-ray diffraction, and Photolumminescence(PL) measurements. At the optimized ZnO buffer layer thickness of 100
$\AA$ , FWHM of$\theta$ -rocking curve of ZnO thin films was minimized to 0.73 degrees and room temperature PL spectra showed that deep level emission was not hardly seen. The optimization of the ZnO buffer layer thickness resulted in improvements of the surface morphology and crystalline quality of ZnO thin films. -
We synthesized Bis(3-N-ethylcarbazolyl) terephthalidene(BECP) and Bis(3-7-ethyl-carbazolyl) cyanoterephthalidene(BECCP) and characterized EL properties of these materials. Our device shows a strong blue emission at 472 nm with a luminance efficiency of 0.9 lm/W at a voltage, a current density, and a brightness of 8 V, 5.7 mA/cm
$^2$ , and 130 cd/m$^2$ , respectively. -
Axial magnetic field(AMF) type electrodes can be increase the interrupting capability of vacuum interrupters. Depending on the design, the principle of the local axial magnetic field arrangement are different. In this paper, a new AMF contact design based on a unipolar field arrangement and its characteristics are introduced. The influence of the unipolar AMF on the arc behavior is described by high-speed video camera. In addition, three-dimensional AMF simulations have been peformed by means of a finite element analysis(FEM) program to analyze the influence of magnetic field distribution on the AMF performance. The high interrupting capability of the unipolar AMF type electrode has been confirmed by three-phase test.
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The stochiometric mix of evaporating materials for the CuGaSe
$_2$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, CuGaSe$_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were 610$^{\circ}C$ and 450$^{\circ}C$ , respectively The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the CuGaSe$_2$ single crystal thin film, we have found that the values of spin orbit splitting Δ So and the crystal field splitting ΔCr were 91 meV and 249.8 meV at 20 K, respectively. From the Photoluminescence measurement on CuGaSe$_2$ single crystal thin film, we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton (D$^{\circ}$ ,X) having very strong peak intensity. Then, the full-width-at-half-maximum(FWHM) and binding energy 7f neutral acceptor bound excision were 8 meV and 35.2 meV, respectivity. By Haynes rule, an activation energy of impurity was 355.2 meV -
Thyristor devices have 3-dimensional complicated structure and were sensitive to temperature characteristics. Therefore, it was difficult to optimize thyristor devices design. We have to consider many design parameter to characterize, and trade-off relations. The important parameters to design thyristor devices are cathode structure, effective line width, cathode-emitter shunt structure, gate structure, doping profile and carrier lifetime. So, we must consider that these design parameters were not acted separately. However, there are many difficulties to determine optimized design parameters by experiment. So, We used specific design software to design thyristor devices, and estimated the thyristor devices characteristics.
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Organic semiconductors based on vacuum-deposited films of fused-ring polycyclic aromatic hydrocarbon have great potential to be utilized as an active layer for electronic and optoelectronic devices. We have fabricated organic thin film transistors(OTFTs) and discuss electrical characteristics of the devices. For the gate dielectric layer, OPTMER PC403 photoacryl(JSR Co.) was spin-coated and cured at 220
$^{\circ}C$ . Electrical characteristics of the device were investigated, where the photoacryl dielectric layer thickness and pentacene active layer thickness were about 0.6$\mu\textrm{m}$ and 800${\AA}$ . -
This paper describes an efficiency improvement of buried contact solar cell (BSCS) with a structure of MgF
$_2$ /CeO$_2$ /Ag/Cu/Ni grid/n$^{+}$ emitter/p-type Si base/p$^{+}$ /Al. Theoretical and experimental investigations were performed on a double layer antireflection (DLAR) coating of MgF$_2$ /CeO$_2$ . We investigated CeO$_2$ films as an AR layer because they have a proper refractive index of 2.46 and demonstrate the same lattice constant as Si substrate. An optimized DLAR coating shewed a reflectance as low as 2.04 % in the wavelengths ranged from 0.4${\mu}{\textrm}{m}$ to 1.1${\mu}{\textrm}{m}$ . BCSC cell efficiency was improved from 16.2 % without any AR coating to 19.9 % by employing DLAR coatings. Further details on MgF$_2$ /CeO$_2$ DLAR coatings on the BCSC cells are presented in this paper.per. -
In this paper, DC and small signal characteristics with different physical parameters are expected for p-HEMTs (Pseudomorphic High Electron Mobility Transistors) with different temperatures ranging from 300K to 623K which are widely used for a low noise and/or ultra high frequency device. A device of 0.2
$\times$ 200${\mu}{\textrm}{m}$ $^2$ dimension having very low noise has been chosen to extract the experimental data. Theoretical prediction has been obtained using a simulaor(HELENA) which needs experimental input data extracted from reverse engineering process. From the results, relation between structural parameters and temperature dependency of electrical characteristics are qualitatively explained to use in the design of descrete and integrated circuits to guarantee the optimal operation of the system. -
Stable polyaniline-dodecylbenzenesulfonic acid (PANI-DBSA) fully dissolved in toluene was obtained by a direct one-step emulsion polymerization technique. The polymerization of aniline was carried out in an emulsion comprising water, toluene and DBSA acting both as a surfactant and a dopant for PANI. After the proper washing process was performed, the conductivities of obtained PANI-DBSA complexes increased with increase APS/Aniline molar ratio and DBSA/Aniline molar ratio. The UV-Vis absorption spectra and TGA thermograms of PANI-DBSA complexes also supported these results. PANI-DBSA/PS blends were prepared by mixing PANI-DBSA complexes with PS in toluene. These blends exhibited electrical conductivity of 0.371S/cm at a low PANI-DBSA content (7 wt.%)
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In this paper, we investigated dielectric properies for BST thin films that was deposited on MgO/Si substrates using RF magnetron sputtering. In here, MgO film was used to perform that a diffusion b arrier between the BST film and Si substrate and a buffer layer to assist the BST film growth. A d eposition condition for MgO films was RF Power of 50W, substrate temperature of room temperature and the working gas ratio of Ar:O
$_2$ were varied from 90:10 to 60:47. Finally we manufactured the cap acitor of Al/BST/MgO/Si/Al structure to know electrical properties of this capacitor through I-V, C-V measurement. In the results, C-V aha racteristic curves was shown a ferroelectric property so we measured P-E. A remanent poliazation and coerceive electric field was present 2$\mu$ C/cm$^2$ and -27kV/cm respectively at Ar:O$_2$ =90:10. And a va clue of dielectric constant was 86 at Ar:02=90:10. -
A new small scaling Lateral Trench Insulated Gate Bipolar Transistor (SSLTIGBT) was proposed to improve the characteristics of the device. The entire electrode of the LTIGBT was replaced with a trench-type electrode. The LTIGBT was designed so that the width of device was no more than 10
$\mu\textrm{m}$ . The latch-up current densities were improved by 4.5 and 7.6 times, respectively, compared to those of the same sifted conventional LTIGBT and the conventional LTIGBT which has the width of 17$\mu\textrm{m}$ . The enhanced latch-up capability of the SSLTIGBT was obtained due to the fact that the hole current in the device reaches the cathode via the p+ cathode layer underneath the n+ cathode layer, directly. The forward blocking voltage of the SSLTIGBT was 125 V. At the same size, those of the conventional LTIGBT and the conventional LTIGBT with the width of 17$\mu\textrm{m}$ were 65 V and 105 V, respectively. Because the proposed device was constructed of trench-type electrodes, the electric field in the device were crowded to trench oxide. Thus, the punch through breakdown of LTEIGBT occurred late. -
In this paper, we propose a charge pump phase-locked loop (PLL) with multi-PFD which is composed of a sequential phase frequency detector(PFD) and a precharge PFD. When the Phase difference is within -
$\pi$ ∼$\pi$ , operation frequency can be increased by using precharge PFD. When the phase difference is larger than │$\pi$ │, acquisition time can be shorten by the additional control circuit with increased charge pump current. Therefore a high frequency operation, a fast acquisition and an unlimited error detection range can be achieved. -
Ferroelectric PZT thin films were fabricated on the RuO
$_2$ /Pt, Pt bottom electrode with a PZT(53/47) metal alkoxide solutions. All PZT thin films showed a uniform grain structure without the presence of rosette structure. The PZT thin films were etched as a function of Cl$_2$ /Ar and additive CF$_4$ into Cl$_2$ (80%)/Ar(20%). The etch rates of PZT thin films were 1970${\AA}$ /min at 30 % additive CF$_4$ into Cl$_2$ (80%)/Ar(20%). The remanent polarization and leakage current density in PZT thin film on the RuO$_2$ /Pt were 64.2${\mu}$ C/cm$^2$ , 1.4${\times}$ 10$\^$ -6/ respectively. -
The IBE(ion beam etching)-induced Schottky barrier variation which depends on various etching history related with ion energy, incident angle and etching time has been investigated using voltage-current, capacitance-voltage characteristics of metal-etched silicon contact and morphology of etched surface were studied using AFM(atomic force microscope). For ion beam etched n-type silicons, Schottky barrier is reduced according to ion beam energy. It can be seen that amount of donor-like positive charge created in the damaged layer is proportional to the ion energy. By contrary, for ion beam etched p-type silicons, the Schottky barrier and specific contact resistance are both increased. Not only etching time but also incident angle of ion beam has an effect on barrier height. Taping-mode AFM analysis shows increased roughness RMS(Root-Mean-Square) and depth distribution due to ion bombardment. Annealing in an N
$_2$ ambient for 30 min was found to be effective in improving the diode characteristics of the etched samples and minimum annealing temperatures to recover IBE-induced barrier variation were related to ion beam energy. -
In this paper, a new lateral insulated gate bipolar transistor (LIGBT) is proposed to improve the latch-up performance without current path underneath the n+ cathode region. The improvement of latch-up performance is verified using the two-dimensional simulator MEDICI and the simulation results on the latch-up current density are 3.12
${\times}$ 10$\^$ -4/ A/$\mu\textrm{m}$ for the proposed LIGBT and 0.94${\times}$ 10$\^$ -4/ A/$\mu\textrm{m}$ for the conventional LIGBT. The proposed SOI LIGBT exhibits 3 times larger latch-up capability than the conventional SOI LIGBT. -
Single phase CuGaS
$_2$ thin film with the highest diffraction peak of (112) at diffraction angle (2$\theta$ ) of 28.8$^{\circ}$ was made at substrate temperature of 7$0^{\circ}C$ , annealing temperature of 35$0^{\circ}C$ and annealing time of 60 min. And second highest (204) peak was shown at diffraction angle (2$\theta$ ) of 49.1$^{\circ}$ . Lattice constant of a and c of that CuGaS$_2$ thin film was 5.37$\AA$ and 10.54$\AA$ respectively. The greatest grain size of the thin film was about 1${\mu}{\textrm}{m}$ . The (112) peak of single phase of CuGaS$_2$ thin film at annealing temperature of 35$0^{\circ}C$ with excess S supply was appeared with a little higher about 10 % than that of no exces S supply And the resistivity, mobility and hole density at room temperature of p-type CuGaS$_2$ thin film with best crystalline was 1.4$\Omega$ cm, 15 cm2/V . sec and 2.9$\times$ 10$^{17}$ cm$^{-3}$ respectively. It was known that carrier concentration had considerable effect than mobility on variety of resistivity of the fabricated CuGaS$_2$ thin film, and the polycrystalline CuGaS$_2$ thin films were made at these conditions were all p-type. -
In this study, ZnO is evaporated to be coated on n-type Si wafer substrate. Refractive coefficient of thin film that is evaporating TiO
$_2$ onto ZnO increases linearly as thickness is getting thinner to have high value and high angle and it satisfies theoretical equation I(x)=Io exp (-$\alpha$ x) theory that represents the strength of photon energy advancing through ZnO thin film. And dielectric constant of TiO$_2$ thin film evaporated onto ZnO is high and$\varepsilon$ $_2$ is smaller than$\varepsilon$ $_1$ . The specimen TiO$_2$ thin film evaporated onto ZnO has much higher dielectric constant when photon energy is increased. -
This paper presents mechanical properties and weatherability of FRP pole used for a distribution line about high strength and good insulation properties. The experiment strength obtained in cantilever beam test are comparable to ES standards. The environmental factors, such as elevated temperatures, high humidity, and corrosive fluids, and ultraviolet(UV) rays, influence on the performance of Polymeric matrix composite.
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In this study, we are studied the electrical conduction and dielectric breakdown properties of insulating varnish. In order to analyze the molecular structure and physical properties of insulating varnishs, FT-lR was used. As the result, it can be confirmed that the peak of alcoholic group appeared in wavenumbers 3452[cm
$\^$ -1], the peak of =CH appeared in 3080[cm$\^$ -1] and the peak of -CH appeared in 2919[cm$\^$ -1] respectively. The following results were obtained from electrical properties of insulating varnish. The amplitude of current density was decreased by thickness increasing and the current density was effected by the thermal energy from external due to temperature increasing. In study temperature dependence of dielectric strength, the specimen of 10[$\mu\textrm{m}$ ] thickness was measurement from room temperature to 180[$^{\circ}C$ ]. It is confirmed that the temperature regions below 60[$^{\circ}C$ ] is due to electron avalanche breakdown and the temperature regions over 60[$^{\circ}C$ ] is due to free volume breakdown which makes electron movements easy. -
Composite insulating materials used in outdoor high voltage equipment are required to have high electric performance because of the miniaturization. The frequence dependence of the permittivity and the loss tangent have important information. In this paper we describe the frequency dependence of the permittivity and the loss tangent for epoxy resin filled with silica and the influence of filler shape on the dielectric properties. The increment of tan
$\delta$ in the low frequency region is caused by the increment of both of the electrical conductivity and the polarization due to the shape of filler and water sbsorbed in and near the interface between the fillers and resins. Result of charge current and discharge measure, electric conduction increased according to voltage. -
This paper reports the developing and manufacturing process of polymeric crossarms in place of conventional crossarms made of steel used for overhead lines. The use of insulated crossarms has been mandatory in order to achieve the required line compaction in the pole. The developed polymer crossarm is characterised by significantly less weight, easier handling, much longer insulation length which leading to reduce the flashover outage from bird nest.
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This paper describes the simulation study, conducted on the propagation characteristics of AE signal in the connection of GIS. In the high voltage and large power system, the equipment with SF
$\sub$ 6/ gas insulation which consists of the component part enclosed in the compressed gas has less affected by the environment than with air insulation. When the breakdown in the electric installation occurs, it takes much time to repair them though. Therefore it is very important to diagnose the propagation characteristics of AE signal in the GIS. So, in this investigation, we make a plane model of 362 kV GIS and modal and harmonic analysis to observe the vibro-acoustic property. Through the result of the analysis, we can make a further understanding on the vibro-acoustic characteristics of AE singnal in the connection of GIS. -
The optical and dielectric properties of TiO
$_2$ thin films prepared with mixtures of Epoxy, bits-(4, 4'-p-toluenesulfonylacidic isoproplylidene)-cyclohexadiol and UVI 6990 in dry sol-gel process were investigated. The absorption peak of the films was showed at 360nm. Photocurrent of the thin films doped with 50 wt% of TiO$_2$ was higher than that of nondoped thin films. Energy gap was lowered from 3.6 to 3.3 eV with increasing amount of TiO$_2$ . Relative dielectric constants of samples were 1.5 to 3 and showed a characteristics of lower dielectric materials. -
The proposed system was composed of pre-processor which was executing binary/high-pass filtering and post-processor which ranged from statistic data to prediction. In post-processor work, step one was filter process of image, step two was image recognition, and step three was destruction degree/time prediction. After these processing, we could predict image of the last destruction timestamp. This research was produced variation value according to growth of tree pattern. This result showed improved correction, when this research was applied image Processing. Pre-processing step of original image had good result binary work after high pass- filter execution. In the case of using partial discharge of the image, our research could predict the last destruction timestamp. By means of experimental data, this Prediction system was acquired
${\pm}$ 3.2% error range. -
NI
$_2$ MnGa-based ferromagnetic shape memory alloys (FSMA) are hoped to be used as robust actuators with high performance and power density, as a replacement of other actuation materials such as thermo-mechanical SMAs and mechanical-electric piezoelectrics. Recently, we have observed significant shape changes under magnetic field application when single- and poly-crystalline forms are used. In the present study, two mechanisms have been proposed to predict the magnetic field-induced shape change as a function of external magnetic field at temperatures below Mr and above Ar. In the case of the field-induced shape change at temperature below M$_{f}$ , paired martensite variants are assumed to form by application of magnetic field. The direction of magnetization in martensites formed in austenite matrix is assumed to be parallel to the applied magnetic field in the case of shape change by application at temperature above Af. Various energies has been considered in the shape change under two mechanisms.s. -
Phase intergrowth in BSCCO thin films have been investigated. It turned out from XRD analyses of these phases that molar fraction of each constituent phase in the intergrowth thin film can be exhibited as a function of substrate temperature and ozone pressure. Superconducting behavior of the intergrowth thin film is also discussed.
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In this study, the magnetic properties for Ni-Zn ferrite were investigated as the function of
$Co_3$ $O_4$ additive contents which was predicted to improve the resonance frequency. Toroid specimens with the composition of N$i_{0.8-x}$ Z$n_{0.2+x}$ F$e_2$ $O_4$ (x = 0, 0.05, 0.1, 0.15) ferrites were preparation by conventional ceramic processing technique. The maximum resonance frequency of 19.905 MHz and the permeability of 90.88 in 10 MHz were attained to the N$i_{0.8}$ Z$n_{0.2}$ F$e_2$ $O_4$ with$Co_3$ $O_4$ 0.3 wt%. Both of the permeability in 10 MHz and the resonance increased to 107.11 and 19.005 MHz respectively for the N$i_{0.8}$ Z$n_{0.2}$ F$e_2$ $O_4$ with$Co_3$ $O_4$ wt% than the N$i_{0.8}$ Z$n_{0.2}$ F$e_2$ $O_4$ / with the free$Co_3$ $O_4$ composition.composition. -
With the use of the electron microscopy and X-ray phase analysis the regularities of carbon deposit formation in process of methane and propane pyrolysis on the zeolites, Kazakhstan natural clays, chrome and bauxite sludge containing metal oxides of iron subgroup, have been studied. In process of over-carbonization the trivalent iron was reduced to metal form. In addition, the carbon tubes of divers morphology had been impregnated with ultra-dispersed metal particles. The kinetic parameters of carbon formation in process of methane decomposition on the zeolite CoO mixture surface were investigated by method of thermo-gravimetric analysis. The morphology and structure of formed carbon fibrils, with the metal particles fixed at their ends, have been investigated, the formation of branched carbon fibrils pattern, so called octopus, being found.
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In this paper, the characteristics of the shielded inductive superconducting fault current limiter(FCL) were simulated and analyzed to search for the parameter to determine FCL operation, Fault current limiting operation can be executed as resistive or inductive type, which is determined by iron-core radius and the number of the primary coil turns. It was considered through this paper that the operation of each was compared and examined about the merit of each mode.
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To implementation of white electroluminescnet device in this paper, two methods were tried without synthesis of new white EL phosphor. At first, ZnS:Mn,Cl was mixed with ZnS:Cu from 20 to 50 weight percents. Second, ZnS:Mn,Cl was mixed with blue dye from 0 to 1.2 weight percents. The devices for experiments were measured as following; current-voltage, emission spectrum, brightness-voltage and CIE coordinate system and frequency properties.
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A typical Mold method is to form a gate electrode, a gate oxide, and emitter tip after fabrication of mold shape using wet-etching of Si substrate. In this study, however, new Mold method using a side wall space structure is used in order to make sharper emitter tip with a gate electrode. Using LPCVD(low pressure chemical vapor deposition), a gate oxide and electrode layer are formed on a Si substrate, and then BPSG(Boro phospher silicate glass) thin film is deposited. After, the BPSG thin film is flowed into a mold as high temperature in order to form a sharp mold structure. Next TiN thin film is deposited as a emitter tip substance. The unfinished device with a glass substrate is bonded by anodic bonding techniques to transfer the emitters to a glass substrate, and Si substrate is etched using KOH-deionized water solution. Finally, we made sharp field emitter array with gate electrode on the glass substrate.
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We fabricated organic electroluminescent(EL) devices with mixed emitting layer of poly (N- vinylcarbazole) ( PVK) , 2,5-bis (5-tert-butyl -2- benzoxaBoly) thiophene ( BBOT) , N,N-diphenyl-N,N- (3-methyphenyl) -1,1-biphenyl-4, 4-thiamine(TPD) and poly(3-hexylthiophene) (P3HT) deposited by LB(Langumuir-Boldgett) method. From the AFM(atomic force microscope) images, the monolayer containing 30% of AA(arachidic acid) showed a roughness value of 28
$\AA$ . In the voltage-current characteristics of ITO/Emitting layer/BBOT/LiF/A1 devices, current density much smaller than that of the spin-coated devices having a same thickness. -
ZnO thin films were deposited on (001) sapphire substrate at various ambient gas pressure by pulsed laser deposition(PLD). Oxygen was used as ambient gas, and oxygen gas pressure was varied from 1.0
${\times}$ 10$\^$ -6/ Torr to 500 mTorr during the film deposition. As oxygen gas pressure increase in the region below critical pressure photoluminescence(PL) intensity in UV and green region increase. As oxygen gas pressure increase in the region above critical pressure photoluminescence(PL) intensity in UV and green region decrease. Each of critical ambient gas Pressures was 350 mTorr for UV emission and 200 mTorr for green emission. -
In this study, the bis(8-oxyquinolino)zinc II (Znq
$_2$ ) were synthesized successfully from zinc chloride (ZnC1$_2$ ) as a initial material. Then, we fabricated red organic electroluminescent device with a dye (DCJTB)-doped and inserted Znq$_2$ between emission layer and cathode layer for increasing EL efficiency. The hole transfer layer is a N,N'-diphenyl-N,N'-bis-(3-methyl phenyl) -1,1'-diphenyl-4,4'- diamine(TPD), and the host material of emission layer is Znq$_2$ . And we study the electrical and optical properties of devices. We found that the device using Znq$_2$ inserting layer result in the increased efficiency. -
The pulsed laser deposition(PLD) technology was used for the deposition of phosphor substance, Gd
$_2$ O$_3$ on commercial glass. An Nd:YAG laser was employed for the deposition (wavelength 266nm, energy up to 100mJ/pu1se, pulse duration is 5ns and repetition rate 10 Hz). With respect to films grown by conventional PLD, this study exhibited the condition at normal temperature. Experiments were done without any reactive gas at a pressure of 10$^{-5}$ ~10$^{-6}$ Torr using second harmonic(λ=532 nm) and fourth harmonic(λ=266 nm) Nd:YAG laser. Analyses of the deposited material grown are performed by EDX, AFM, SEM, PL meseurements. -
입사면에서 발생하는 열을 효율적으로 제거하기 위하여 Yb:YAG 결정의 표면에 sapphire 창을 부착하여 레이저를 발진 시켰다. Yb:YAG 결정에서 발생하는 열이 sapphire 창을 통하여 구리판으로 전달되는 경우 와 Yb:YAG 결정의 측면에서 냉각하는 경우의 레이저 출력을 측정하여 각각의 레이저 발진 특성을 비교하여 보았다. 여기면을 sapphire 창으로 냉각하는 micro-chip Yb:YAG 레이저의 레이저 에너지 전환 효율은 38%였으며 레이저 발진 문턱값은 4 kw/mm
$^2$ , slope efficiency는 56%로 측정되었다. Sapphire 창을 사용하는 경우 표면에서의 열전달도는 10 W/mm$^2$ 이상으로 관측되었다. Yb:YAG의 도핑율, 출력경의 반사율 등을 레이저 변수를 최적화할 경우 같은 구조에서 50 W급 레이저도 발진 가능할 것으로 예상된다. -
We studied the electro-optical (EO) performance in the vertical-alignment (VA) - l/4
$\pi$ cell photoaligned with polarized UV exposure on a homeotropic photopolymer surfaces. Excellent voltage-transmittance curve in the VA - l/4$\pi$ cell photoaligned with polarized UV exposure for 3 min on the photopolymer containing cholesterol group of 8% can be achieved. The V-T characteristics in the VA-l/4$\pi$ cell photoaligned on the photopolymer surface can be improved by increasing cholesteryl group. For response time measurement, the transmittance characteristics of the VA-l/4$\pi$ cell photoaligned on the photopolymer surface was better than that of the VA-l/4$\pi$ cell rubbingaligned on a polyimide(Pl) surface. -
When varistors for circuit protection is used at high voltage, it's operation properties were unstable because of leakage current and nonlinear coefficient with grain size. For the purpose of improving of ZnO varistor properties, high voltage ZnO varistor was fabricated with Y
$_2$ O$_3$ addition. Electrical properties were investigated according to sintering conditions and mixing conditions. ZnO varistors was shown ohmic Properties when it's applied voltage was below critical voltage. It was shown non-ohmic properties over critical voltage, because current was increased with decreasing resistance. -
The BST thin films to composite (Ba
$\sub$ x/Sr$\sub$ l-x/)TiO$_3$ using sol-gel method were fabricated on Pt/Ti/SiO$_2$ /Si substrate. The thin film capacitor to be ferroelectric materials was investigated by structural and electrical properties. BST solution was composited by moi ratio, and then spin-coated (from 3 times to 5 times coating on Pt/SiO$_2$ /Si substrate. Thickness of BST ceramics thin films are about 2600∼2800[${\AA}$ ] in 3 times deposition. The property of leakage current was stable when the applied voltage was 3[V]. Leakage current of 3 times coated BST thin film was 10$\^$ -9/∼10$\^$ -11/[A] at 0∼3[V]. -
The
$\beta$ -SiC+ZrB$_2$ and$\beta$ -SiC+TiB$_2$ ceramic electroconductive composites were pressureless-sintered and annealed by adding l2wt% A1$_2$ $O_3$ +Y$_2$ $O_3$ (6 : 4wt%) powder as a function of sintering temperature. The relative density showed highest value of 84.92% of the theoretical density for SiC-TiB$_2$ at 190$0^{\circ}C$ sintering temperature. The phase analysis of the composites by XRD revealed of$\alpha$ -SiC(6H), TiB$_2$ ,$Al_{5}$ Y$_2$ $O_{12}$ and$\beta$ -SiC(15R). Flexural strength showed the highest of 230 MPa for SiC-ZrB$_2$ composites sintered at 190$0^{\circ}C$ . The vicker's hardness increased with increasing sintering temperature and showed the highest for SiC-ZrB$_2$ composites sintered at 190$0^{\circ}C$ . Owing to YAG, the fracture toughness showed the highest of 6.50 MPa . m$^{1}$ 2/ for SiC-ZrB$_2$ composites at 190$0^{\circ}C$ . The electrical resistivity was measured by the Rauw method from$25^{\circ}C$ to$700^{\circ}C$ . The electrical resistivity of the composites showed the PTCR(Positive Temperature Coefficient Resistivity).). -
The cutting performance of a machine depends on the ability of the design of the acoustic horn to facilitate an increase in tool-tip vibration, allowing a significant amount of material to be removed. In this paper, three kinds of acoustic horns were designed and FEM was used to estimate displacement magnifications of horn tips. An optimization procedure for the profile has been followed to obtain maximum magnification, for higher rate of material removal and safe working stresses for the horn material.
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In this paper, we have explained electrical characteristics of a step-down Rosen type piezoelectric transformer for AC-adapter. When the electric voltage is applied to the driving piezoelectric vibrator polarized in the longitudinal direction, then output voltage is generated at the generating piezoelectric vibrator polarized in the thickness direction due to the piezoelectric effects. Output voltage and current from a 11-layered and a 13-layered piezoelectric transformer were measured under the various conditions of loads and frequencies. We measured resonant frequency from impedance curve. It was shown from experiments that output voltage has increased and resonant frequency has changed according to various resistor loads. Output current has changed inversely proportional to resistances.
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A linear ultrasonic motor was designed by a combination of the first longitudinal and fourth bending mode, the motor consisted of a straight aluminum alloys bar bonded with a piezoelectric ceramics element as a driving element. That is, L
$_1$ -B$_4$ linear ultrasonic motor can be constructed using a multi-mode vibrator of longitudinal and bending modes. The simulation with variation of material characteristics of piezoceramic were performed as use of finite element analysis ANSYS 5.5, such as elastic compliance, piezoelectric constant, electro-mechanical coupling coefficient, poisson's ratio and density. The results of simulation, elastic compliance constant s$_{11}$ and piezoelectric constant d$_{31}$ had the most of influence on the elliptic-motion. This results consist with using transverse effect of material. The used motor were piezoceramics of 4 layers, and the dimensions were 65$\times$ 5$\times$ 3.5mm(LxWxt).). -
The dielectric and piezoelectric properties of Pb(Mn
$\_$ 1/3/Nb$\_$ 2/3)O$_3$ -Pb(Zr,Ti)O$_3$ ceramics were investigated as a function of Zr/Ti ratio. Curie temperature was increased with the increase of Ti amount. At the Zr/Ti ratio of 0.495/0.505, dielectric constant and electromechanical coupling factor(kp) showed the maximum value of 1159 and 0.523 respectively. -
The BaTiO
$_3$ +10wt%Nb$_2$ O$_{5}$ ceramics were prepared by conventional mixed oxide method. The structural and dielectric properties of the BaTiO$_3$ +10wt%Nb$_2$ O$_{5}$ ceramics with the sintering temperature were investigated. Increasing the sintering temperature, the 2$\theta$ value of BaTiO$_3$ peaks were shifted to the higher degree and intensity of the BaTiO$_3$ and BaNbO$_3$ peaks were increased. In the BaTiO$_3$ +10wt%Nb$_2$ O$_{5}$ ceramics sintered at 135$0^{\circ}C$ and 1375$^{\circ}C$ , the grain was fine and uniform. Increasing the sintering temperature, the pore was decreased and the dielectric constant was increased. In the BaTiO$_3$ +10wt%Nb$_2$ O$_{5}$ ceramics sintered at 1375$^{\circ}C$ , the dielectric constant and dielectric loss were 5424, 0.02 respectively.ctively. -
In this paper, the microstructure and the dielectric properties of the Sr
$_{1-x}$ Ca$_{x}$ TiO$_3$ (0$\leq$ $\chi$ $\leq$ 0.2) -based grain boundary layer ceramics were investigated. The specimens were sintered from 142$0^{\circ}C$ to 152$0^{\circ}C$ for 4hr. in$N_2$ gas. The 2nd phase formed by thermal diffusing from the surface lead to a very high apparent dielectric constant,$\varepsilon$ $_{r}$ >50000. The structural properties of the specimens were studied by X-ray diffraction and SEM, EDX. All specimens exhibited cubic structure. Increasing content of Ca, the peak intensity were decreased.ed.d. -
The microstructure, V-I characteristics, and stability of ZnO-Pr
$_{6}$ O$_{11}$ -CoO-Cr$_2$ O$_3$ -Y$_2$ O$_3$ based vairstors were investigated with cooling rate in the range of 2~8$^{\circ}C$ /min. The cooling rate relatively weakly affected the microstructure, and the varistor voltage and the leakage current in the V-I chracteristics. But the nonlinear exponent relatively strongly affected by cooling rate. And the cooling rate also greatly affected the stability for DC stress. In gross, the varistors cooled with 4$^{\circ}C$ /min exhibited the highest performance in the densification, nonlinearity, and stability. Especially, they exhibited a high stability, in which the variation rate of the varistor voltage and the nonlinear exponent is -1.44% and -4.85%, respectively, under more severe DC stress such as (0.80 V$_{1mA}$ 9$0^{\circ}C$ /12 h)+(0.85 V$_{1mA}$ 115$^{\circ}C$ /12 h)\`(0.90 V$_{1mA}$ 12$0^{\circ}C$ /12 h)+(0.95 V$_{1mA}$ 1$25^{\circ}C$ /12 h)+(0.95 V$_{1mA}$ 15$0^{\circ}C$ /12 h). It should be emphasized that the stability of these varistors is much superior to that of others.s.of others.s. -
The I-V characteristics and its stability of ZPCCL-based ceramic varistors doped with La
$_2$ O$_3$ in the range of 0.0~4.0 mol% were investigated. The density of ceramics was increased in the range of 4.7~5.8 g/cm$^3$ with increasing La$_2$ O$_3$ content. As La$_2$ O$_3$ content is increased, the varistor voltage was decreased in the range of 503.49-9.42 V/mm up to 2.0 mol%, whereas increasing La$_2$ O$_3$ content further caused it to increase. The ZPCCL-based varistors were characterized by nonlinearity, in which the nonlinear exponent is in the range of 3.05~82.43 and leakage current is in the range of 0.24-100.22$\mu$ A. Among ZPCCL-based varistors, 0.5 mol% added-varistors exhibited an excellent nonlinearity, in which the nonlinear exponent is 82.43 and the leakage current is 0.24$\mu$ A. Furthermore, they exhibited a high stability, in which the variation rate of the varistor voltage and the nonlinear exponent was -1.11% and -6.72%, respectively, under DC stress, such as (0.80 V$_{1mA}$ 9$0^{\circ}C$ /12h)+(0.85 V$_{1mA}$ 115$^{\circ}C$ //12h) +(0.90 V$_{1mA}$ 12$0^{\circ}C$ //12h)+(0.95 V$_{1mA}$ 1$25^{\circ}C$ //12h)+(0.95 V$_{1mA}$ 15$0^{\circ}C$ //12h). Consequently, it was estimated that ZPCCL-based ceramics will be applied to development of Pr$_{6}$ O$_{11}$ based ZnO varistors having a high performance.e.rformance.e. -
The electrical properties of Pr
$_{6}$ O$_{11}$ -based ZnO varistors composed of ZnO-Pr$_{6}$ O$_{11}$ -CoO-Cr$_2$ O$_3$ -Dy$_2$ O$_3$ - based ceramics were investigated with CoO content in the range of 0.5~5.0 mol%. As CoO content is increased, the average grain size and the density were increased in the range of 9.86~27.22$\mu$ m and in the range of 5.25-5.55 g/cm$^3$ , respectively. The varistor voltage was decreased in the range of 235.32~86.01 V/mm due to the increase of average grain size with CoO content. The varistors doped with CoO in the rage of 1.0~2.0 mol% exhibited a high nonlinearity, in which is above 55 in the nonlinear exponent and below 1.5$\mu$ A in the leakage current. Increasing CoO content further greatly decreased the nonlinearity.ity.ity. -
Recently we have reported that the meander-patterned amorphous FeCoSiB films exhibit large change in their high frequency impedance by applying a strain, suggesting that the films are very attractive for making of a highly sensitive strain sensor elements. In this study, the effect of anisotropy on a change in the impedance of sputtered amorphous film patterns was investigated in the frequency range from 1MHz to 1GHz. As a function of applied strains, the high frequency impedance was extremely changed in the case of film patterns with transverse anisotropy due to excellent magnetomechanical coupling properties. As a summary, the maximum figure of merit f has measured about 2600 in the case of transverse anisotropy, and about 500 in the case of longitudinal anisotropy at 500 MHz. These values of F are approximately more than 1000 times higher than that of a conventional metal strain gauge (F 2) and more than 10 times higher than that of a semiconductor gauge (F 200).
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The degradation characteristics versus MgO Additive for the ZnO ceramic devices fabricated by the standard ceramic techniques is investigated in this study. It were made these devices be basic Matsuoka's composition. Especially, MgO were added to analyze the degradation characteristics and sintered in air at 1300
$^{\circ}C$ . The conditions of DC degradation test were 115${\pm}$ 2$^{\circ}C$ for 12h. Using XRD and SEM, the phase and microstructure of samples were analyzed respectively. The elemental analysis in the microstructures was used by EDS, E-J analysis was used to determine${\alpha}$ . Frequency analysis was accomplished to understand the relationship between R$\sub$ g/ and$R_{b}$ with the electric stress at the equivalent circuit. -
The mechanical and phase transformation of the cold isostatically pressed
$\alpha$ -SiC ceramic were investigated as a function of the sintering temperature. The result of phase analysis by XRD revealed 6H, 4H, 3C and phase transformation between 6H and 4H showed a sudden change over 200$0^{\circ}C$ . However, the alongrightarrow$\beta$ reverse transformation did not occur to any sintering temperature. The relative density and the mechanical properties of$\alpha$ -SiC ceramic was increased with increased sintering temperature. The flexural strength rapidly inclosed below 210$0^{\circ}C$ and showed the highest value of 410 MPa at 220$0^{\circ}C$ . This reason is because crack was propagated through surface flaw. The fracture toughness showed the highest value of 3.3 MPa.m$_{1}$ 2/ at 220$0^{\circ}C$ . -
Thin films of vanadium oxide(VO
$\sub$ x/) have been deposited by r.f. magnetron sputtering from V$_2$ O$\sub$ 5/ target in gas mixture of argon and oxygen. The oxygen/(oxygen+argon) partial pressure ratio is changed from 0% to 8%. Crystal structure, chemical composition and bonding properties of films sputter-deposited under different oxygen gas pressures are characterized through XRO, XPS, RBS and FTIR measurements. All the films prepared below 8% O$_2$ are amorphous, and those prepared without oxygen are gray indicating the presence of V$_2$ O$\sub$ $_4$ / phase in the films. V$_2$ O$\sub$ 5/ and lower oxides co-exist in sputter-deposited films and as the oxygen partial pressure is increased the films become more stoichiometric V$_2$ O$\sub$ 5/. The increase of O/V ratio with increasing oxygen gas pressure is attributed to the partial filling of oxygen vacancies through diffusion. It is observed that the oxygen atoms. located on the V-O plane of V$_2$ O$\sub$ 5/ layer participate more readily in the oxidation process. -
Chalcogenide glassy semiconductors(CGS) can be obtained by the melt quenching technique. We have investigated the thin film heterostructures : metal-chalcogenide glassy semiconductors, where metal is copper, and chalcogenide glassy semiconductors are glasses of the system As-Se. CU/CGS film heterostructure were produced in the vacuum evaporator by the method of vacuum thermal evaporation. Doped films are very sensitive to external actions, and this property allows developing supersensitive precision sensors of temperature, humidity, illumination, and etc. based on them. Cu/CGS film has shown that resistance strongly depend on the temperature. The ratio of resistance vs. temperature has shown over a 2 k
$\Omega$ /degree. The slop of temperature and resistance shows linear. -
MI(Magneto-Impedance) sensor which is made by thin films has significantly high detecting sensitivity in weak magnetic field. It also has a merit to be able to build in low power system. Its structure is simple, which makes it easier to prepare a miniature. In this study, its magnetic permeability and anisotropy field(H
$\sub$ k/) as a function of a thickness of sputtered amorphous CoZrNb thin film with high saturation magnetostriction and excellent soft magnetic property are investigated. In order to make a uniaxial anisotropy, thin film was subjected to post annealing with a static magnetic field with 1KOe intensity at 250, 300, and 320$^{\circ}C$ for 2 hour. Anisotropy field(H$\sub$ k/)of thin film is measured by using MH loop tracer. Its magnetic permeability of thin film is measured over the frequency range from 1 MHz to 750MHz. It has shown that the magnetic permeability of amorphous CoZrNb thin film is decreased due to the skin effect with increasing a thickness of CoZrNb thin film, and hence its driving frequency is lowered. -
Abstract-Si direct bonding(SDB) technology is very attractive for both Si-on-insulator(SOI) electric devices and MEMS applications because of its stress free structure and stability. This paper presents on pre-bonding according to HF pre-treatment conditions in Si wafer direct bonding. The characteristics of bonded sample were measured under different bonding conditions of HF concentration, and applied pressure. The bonding strength was evaluated by tensile strength method. The bonded interface and the void were analyzed by using SEM and IR camera, respectively. Components existed in the interlayer were analysed by using FT-lR. The bond strength depends on the HF pre-treatment condition before pre-bonding (Min : 2.4kgf/cm
$^2$ ∼Max : 14.9kgf/cm$^2$ ). -
In this study, a micro-glucose sensor was fabricated by micromachining technology and its sensing characteristics were investigated. The 7740 pyrex glass was used as the bottom substrate and anisotropically etched silicon wafer was used as the top substrate. The size of the fabricated microchip is 1.58
${\times}$ 1.58mm$^2$ . It is shown that output current exhibits a linear change according to glucose concentration (100 mM ∼ 300 mM). It is also shown that the response time for glucose was within 240 sec. It was followed by a saturation trend within 50 sec. The g1ucose sensor with Fc$\^$ +/ exhibits relatively higher sensitivity than that without Fc$\sub$ +/ for output current. -
Spinel
$LiMn_{2-y}$ $M_{y}$ $O_4$ powder was prepared solid-state method by calcining the mixture of LiOH -$H_2O$ , Mn$O_2$ , ZnO and MgO at 80$0^{\circ}C$ for 36h. To investigate the effect of substitution with Mg, Zn cation, charge-discharge experiments and initial impedance spectroscopy performed. The structure of$LiMn_{2-y}$ $M_{y}$ $O_4$ crystallites was analyzed from powder X-ray diffraction data as a cubic spinel, space group Fd3m. all cathode material showed spinel phase based on cubic phase in X-ray diffraction. Ununiform which calculated by (111) face and (222) face was constant in spite of the change of y value, except PUf\ulcorner LiM$n_2$ $O_4$ . The discharge capacities of the cathode for the cation subbstitUtes$LiMn_{2-y}$ $M_{y}$ $O_4$ /Li cell at the 1st cycle and at the 40th cycle were about 120~124 and 108~112mAh/g except LiM$n_{1.9}$ Z$n_{0.1}$ $O_4$ /Li cell, respectively. This cell capacity is retained by 93% after 40th cycle. AC impedance of$LiMn_{2-y}$ $M_{y}$ $O_4$ /Li cells revealed the similar resistance of about 65~110$\Omega$ before cycling. before cycling.g.g. -
We have investgated the photoisomerization using light irradiation 8A5H LB film accumulated by monolayer and three layers on an ITO. We determined electrochemical measurement by using cyclic voltammetry with a three-electrode system, An Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode measured in 0.1mol/L NaClO
$_4$ solution. The scan rate was 100mv/s. -
This detailed study of electrical, crystallographic and optical properties in Al doped ZnO thin films prepared by Facing Targets Sputtering(FTS), where strong internal magnets were contained in target holders to confine the plasma between the targets is described. Optimal transmittance and resistivity was obtained by controlling flow ratio of O
$_2$ gas. When the O$_2$ gas ratio of 0.25 and substrate temperature R.T., ZnO:Al thin film deposited had strongly oriented c-axis and the lower resistivity ( <10$\^$ -4/$\Omega$ cm). The optical transmittance was above 80% in visible range. -
KAM200 which can be used electroluminescence binder is cyano material. In this study, we have fabricated KAM200 thin film by Spin-Coating method. And we have studied the electical properties of KAM200 thin films. In the I-V characteristics, the current decreases as the voltage overflow definite voltage immediately. And that definite voltage depend on thickness of KAM200 material. In the case of thickness is 1.9[
$\mu\textrm{m}$ ], definite voltage is 7[V]. And that's electrical field 3.86[MV/m]. The dielectric properties of KAM200 thin film is investigated by measuring dielectric dispersion and absorption. KAM200's Relative dielectric constant is 10.25, and it has high permittivity compared with different materials. -
In this study, 70/30 mol% P(VDF-TrFE) copolymer thin films were prepared by physical vapor deposition, and dielectric properties with frequency were investigated. From results of TA(Thermal Analysis), the Curie transition temperature and melting temperature were observed at 118.8
$^{\circ}C$ and 146$^{\circ}C$ , respectively. Therefore, while thin films were prepared, the substrate temperature was varied from 30$^{\circ}C$ to 90$^{\circ}C$ . The dielectric constant decreased with increasing frequency. At measuring frequency of 1kHz, the relative dielectric constant increased from 3.643 to 23.998 with increasing substrate temperature from 30$^{\circ}C$ to 90$^{\circ}C$ . As a result of dielectric loss factor,${\alpha}$ -relaxation and${\beta}$ -relaxation were observed near at 100Hz and 1MHz, respectively. And the magnitude of${\alpha}$ -relaxation decreased and that of${\beta}$ -relaxation increased with increasing substrate temperature. -
The properties of LiMnO
$_2$ was studied as a cathode active material for lithium polymer batteries. LiMnO$_2$ cathode active materials were synthesized by the reaction of LiOH .$H_2O$ and Mn$_2$ O$_3$ at various temperature under argon atmosphere. For lithium polymer battery applications, the LiMnO$_2$ cell was characterized electrochemically by charge-discharge experiments and a.c. impedance spectroscopy. And the relationship between the characteristics of powders and electrochemical properties was studied in this research. A maximum discharge capacity of 160-170 mAh/g for ο-LiMnO$_2$ cell was achieved. Used that SP270 as electric active material in LiMnO$_2$ , it is excellent than property of electric active material used Acetylene black or KS6 at charge/discharge capacity. -
Fe-base amorphous films exhibit large saturation magnetostriction and soft magnetic Properties, which make them suitable for strain sensor applications. Most important material properties for the performance of these elements are the superior soft magnetic properties, such as high permeability and small coercive force, as well as magnetoelastic properties. It is well known that the strain generated in film deposition and/or post-heat treatment processes is one of important material properties, which effects on the soft magnetic properties of the film via magnetoelastic coupling. In this study, the effect of an isotropic strain in plane of magnetic films have been performed experimently. Amorphous films with the composition of (F
$e_{90}$ $Co_{10}$ )$_{78}$ S$i_{l2}$ $B_{10}$ were employed in this study. The film with 5${\mu}{\textrm}{m}$ thick was deposed onto the polyimide substrate with 50${\mu}{\textrm}{m}$ thick by virtue of RF sputtering. The film was subject to post annealing with a static magnetic field with 500Oe magnetic field intensity at 35$0^{\circ}C$ for 1 hour. The polyimide substrate with the film was bonded with an adhesive on PZT piezoelectric substrate with 600${\mu}{\textrm}{m}$ thick in applying voltage of 500V. The change in MH loops of films due to the isotropic strain was measured by using VSM. The coercive force was evaluated from MH loops. It has shown in the results that M-H loops of films are subject to change considerably with a dc voltage, resulting of the magnetization rotation from normal to plane direction as the applied voltage is changed from 500V to 250V.50V.V. -
High voltage induction motors are widely used in industrial factory because have many benefits. But the insulated materials of induction motor are aged by using time, electrical, thermal, circumstantial stresses and so on. Motor failures are occurred by these deterioration phenomena and give rise economic problems to user. In many motor failures, insulated material problems of stator winding happen frequently and occupy high percentages in the failure source. In this paper, the testing specimen(motorette) is manufactured by modeling of stator winding of high voltage induction motor and accelerating test is carried out. Partial discharge signals detected by RF sensor are used to analyze deterioration condition of stator windings. According to aging time, the 3D (
${\Phi}$ -Q-N) distribution and skewness of partial discharge signals are changed. -
This paper provides the result of analysis of the structure and I-V characteristics of D.C. 1500 V surge arresters which were installed in railway line currently. As Porcelain housed surge arresters have unstable elements such as exploding and dispersion, so it is thought that the system is protected more stably with replacement of polymer housing. The adoption of gap mitigates the voltage stress which is degradation factor of surge arresters and the research is needed to enhance the life characteristic in additive and manufacturing process. Therefore, it is thought that the research should be continued to develop homemade the surge arresters for D.C. railway line as well as transmission line.
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In this thesis, the microstructure and electrical properties of ZnO varistors were investigated according to ZnO varistors with various formulation. A∼E's ZnO varistor ceramics were exhibited good density, 95% of theory density and low porosity, 5%, wholly. The average grain size of A-E's ZnO varistor ceramics exhibited 11.89
$\mu\textrm{m}$ , 13.57$\mu\textrm{m}$ , 15.44$\mu\textrm{m}$ , 11.92$\mu\textrm{m}$ , 12.47$\mu\textrm{m}$ , respectively. Grain size of C's ZnO varistor is larger and grain size of A and D's are smaller than other varistors. In the microstructure, A∼E's ZnO varistor ceramics sintered at l130$^{\circ}C$ was consisted of ZnO grain(ZnO), spinel phase(Zn$\sub$ 2.33/Sb$\sub$ 0.67/O$_4$ ), Bi-rich Phase(Bi$_2$ O$_3$ ) and inergranular phase, wholly. Reference voltage of A∼E's ZnO varistor sintered at 1130$^{\circ}C$ decreased in order D, E > A > B > C's ZnO varistors. Nonlinear exponent of varistors exhibited high characteristics, above 30, wholly. Consequently, C's ZnO varistor exhibited good nonlinear exponent, 68. Lightning impulse residual voltage of A, B, C and E's ZnO varistors suited standard characteristics, below 12kV at current of 5kA. -
The distribution line through which electricity is supplied from substation to customer generally varies by underground line and overhead line. In contrast that the underground line is shielded, the overhead lines do not have the shield layer. To overcome this weak point of the overhead lines, the aerial bundled cable(ABC) connection systems have been developed. The basic concept of the ABC connection system is the application of the underground cable system containing complete shield layer to the overhead cable system. The ABC system is the innovative technologies which enable the prevention of electric shocks, reduction of the maintenance charge and damage of the cable. This paper give a full detail of vertical connection system applied within a country.
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In this experiment, an attempt to use the sludge pellets as catalyst for NO removal from simulated gas is experimentally investigated by using cylinder type reactor and packed-bed reactor. An experimental investigation has been conducted for NO concentration of 50[ppm], 100[ppm], 200[ppm] balanced with air, a gas flow rate of 5[1/min]. Ac voltage to discharge the gases was supplied. In the result, NOx removal rate in packed bed reactor is higher than that in cylinder type reactor. it is thought that plasma density in contact point of BaTiO
$_3$ is significantly higher than that in cylinder reactor. -
This paper presents leakage magnetic field and leakage inductance calculations in current transformer by means of 3-D Integral methods. From the distribution diagram of leakage magnetic flux to be analyzed using program called TRACAL3, it confirms a parallel to the winding axis direction of the leakage flux lines in the air gap between the windings. The leakage inductances L
$\sub$ r1/ and L$\sub$ R2/ of the primary and secondary windings were calculated, their values are 4.23 mH and 0.49 mH, respectively. They are also similar to the measured values of the leakage inductances for the experimental verification, 4.06 mH and 0.47 mH. -
본 논문은 일 라이트의 항균 방취 및 세균 흡착 능력을 공기조화기 및 공기청정기의 프리필터로 함침하여 사용함으로서 필터의 탈취 시험결과는 암모니아, 메틸멀캅탄, 트리메틸아민, 황화수소를 가지고 실험결과 거의 모든 가스를 흡착하였고 필터의 항균시험 결과 두가지의 균주를 사용하였는데 균주 1 - Staphylococcus aureus ATCC 6538과 균주 2 - Escherichia coli ATCC 25922는 균 감소율이 99.9% 이상을 보였다. 따라서 본 논문이 의도하였던 모든 특성을 만족한 결과가 도출되었다.
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We have developed a metal detector, which was made with two Hall-senors. We could detect the minute variation of terrestrial magnetism by the metal detector and the detector was handy to carry because it had been runned by a dry cell. So it will be utilized in finding ferromagnetic substances buried in the earth.
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In this study, the electric door lock using the password input system for security improvement was fabricated. The security has been improved by using the multiple micro process. The controller with solenoid valve has been designed indirect driving system for releasing the door lock system. Also, the self checkup system for improving the trustworthy was developed with two kinds of micro process. The results will be applied IC card system and fingerprint identification system for security improvement.
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Recently, the battery charging technology and reducing technology of harmonics on AC input line are rising importantly according to increasing electrical facilities that it has been replaced battery with emergency power. In this study, I proposed that an auto-charging circuit of battery has low cost with simple-construction circuit, relative, harmonics reduction with diode tap-change method, high reliability of system for using characteristics of thyristor switching. In case of this circuit, convenience and reliability of maintenance of battery power units were more improved. 1 think that it is resulted in effect of prevention to shortening of battery life from over-charging and over-discharging and decrease of harmonics obstacle on AC input line.
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In this paper, we design and fabricate the high-efficiency and low-power switched-capacitor DC-DC converter. This converter consists of internal oscillator, output driver and output switches. The internal oscillator has 100kHz oscillation frequency and the output switches composed of one pMOS transistor and three nMOS transistors. According to the configuration of two external capacitors, the converter has three functions that are the Inverter, Doubler and Divider. The proposed converter is fabricated through the 0.8
$\mu\textrm{m}$ 2-poly, 2-metal CMOS process. The simulation and experimental result for fabricated IC show that the proposed converter has the voltage conversion efficiency of 98% and power efficiency more than 95%. -
In this paper, the basic characteristics of flat fluorescent lamp using ultraviolet generate from gas discharge and powder type electrolyminescent display(P-ELD) using a phenomenon of the light emission eaused by the electrical field applied to phosphor are studied. The lamp is a simple structure with insulator layer, phosphor layer, and gas gap. Current(displacement current + discharge current) in flat fluorescent lamp using.
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The ZnSe sample grown by chemical bath deposition (CBD) method were annealed in Ar gas at 450
$^{\circ}C$ Using extrapolation method of X-ray diffraction pattern, it was found to have zinc blend structure whose lattice parameter a$\_$ o/ was 5.6687${\AA}$ . From Hall effect, the mobility was likely to be decreased by impurity scattering at temperature range from 10 K to 150 K and by lattice scattering at temperature range from 150 K to 29 3K. The band gap given by the transmission edge changed from 2.7005 eV at 293 K to 2.8739 eV at 10 K. Comparing photocurrent peak position with transmission edge, we could find that photocurrent peaks due to excition electrons from valence band,$\Gamma$ $\_$ 8/ and$\Gamma$ $\_$ 7/ to conduction band$\Gamma$ $\_$ 6/ were observed at photocurrent spectrum. From the photocurrent spectra by illumination of polarized light on the ZnSe thin film, we have found that values of spin orbit coupling splitting Δso is 0.0981 eV. From the PL spectra at 10 K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be 0.0612 eV and the dissipation energy of the donor -bound exciton and acceptor-bound exciton to be 0.0172 eV, 0.0310 eV, respectively. -
In SiC semiconductor device processing, it needs high temperature anneal for activation of ion implanted dopants. The macrosteps, 7~8nm in height, are formed on the surface of SiC substrates during activation anneal. We have investigated the effect of thermally-grown SiO
$_2$ layer on the suppression of macrostep formation during high temperature anneal. The cap oxide layer was found to be efficient for suppression of macrostep formation even though the annealing temperature is as high as the melting point of SiO$_2$ . The thin cap oxide layer (10nm) was evaporated during anneal then the macrosteps were formed on SiC substrate. On the other hand the thicker cap oxide layer (50nm) remains until the anneal process ends. In that case, the surface was smoother and the macrosteps were rarely formed. The thermally-grown oxide layer is found to be a good material for the suppression of macrostep formation because of its feasibility of growing and processing. Moreover, we can choose a proper oxide thickness considering the evaporate rate of SiO$_2$ at the given temperature. -
So far, the design methods of quartz crystal resonator have been developed. Recently, as the electronic package and semiconductor modules become smaller, the need to minimize the sizes of crystal components grows larger. but Minimizing crystal plate sizes has limitations because its temperature-frequency characteristics is worse and unwanted resonances occur. so appropriate design of electrode size and crystal plates is necessary. In this palter, Two-dimensional governing equations for electroded piezoelectric crystal plates with general symmetry have been solved from deduced equations from three-dimensional equations of linear piezoelectricity in most cases. In practice, electroded piezoelectric crystal plates have three-dimensional geometry, so simplified 2-dimensional equations and 2-D modeling are insufficient for explaining its resonance modes and characteristics. So, three-dimensional FEM(finite element method) analysis is done and its effectiveness is verified from analyzing practical crystal resonator model.
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The dielectric constants and dielectric losses of ZrTiO
$_4$ thin films deposited by DC magnetron reactive sputtering were investigated. The paraelectric properties were measured in the 100kHz range. As the deposition temperature increased (up to 67$0^{\circ}C$ ), the dielectric losses (tan$\delta$ ) decreased (down to 0.017$\pm$ 0.007), while the dielectric constants ($\varepsilon$ ) were in the range of 35$\pm$ 7. Post annealing at 80$0^{\circ}C$ in oxygen for 2h reduced tan$\delta$ down to 0.005$\pm$ 0.001, higher than those of well-sintered bulk ZrTiO$_4$ . -
In this study, unity current gain frequency f
$\_$ T/ of GaAs MESFET is predicted with different temperatures up to 400$^{\circ}C$ . Temperature dependence parameters of the device including intrinsic carrier concentration n$\_$ i/ effective mass, depletion width are considered to be temperature dependent. Small signal parameters such as gate-source, gate dran capacitances C$\_$ gs/ C$\_$ gd/ are correlated with transconductance g$\_$ m/ to predict the unity current gain frequency. The extrinsic capacitance which plays an important roles in high frequency region has been taken into consideration in evaluating total capacitance by using elliptic integral through the substrate. From the results, f$\_$ T/ decreases as the temperature increases due to the increase of small signal capacitances and the mobility degradation. Finally the extrinsic elements of capacitances have been proved to be critical in deciding f$\_$ T/ which are originated from the design rule of the device. -
In this work, we had synthesis the GaN powder by direct reaction between Ga and NH
$_3$ at the temperature range of 1000∼1150$^{\circ}C$ , and investigated the reaction condition dependence of the GaN yield and some properties of GaN powder. The synthesized powder had Platelet and prismatic shape and showed hexagonal crystalline structure with the lattice constants of a= 3.1895${\AA}$ , c= 5.18394${\AA}$ , and the ratio of c/a = 1.6253. The GaN powder synthesis processes were examined based on the oxidation process of mater, and found as combined with mass transport process for the initial stage and diffusion-limited reaction for the extended reaction. -
In this study, the ZnS nanosized thin films were grown by the solution growth technique (SGT), and their structural and optical properties were examined. X-ray diffraction patterns showed that the ZnS thin film obtained in this study had the cubic structure (
$\beta$ -ZnS). With decreasing growth temperature and decreasing concentration of precursor solution, the surface morphology of film was found to be improved. In particular, this is the first time that the surface morphology dependence of ZnS film grown by SGT on the ammonia concentration is reported. The energy band gaps of samples were shown to vary from 3.69 eV to 3.91 eV, demonstrating that the quantum size effect of SGT grown ZnS is remarkable. Photoluminescence (PL) peaks were observed at the positions corresponding to the lower energy than that to energy band gap, illustrating that the surface states were induced by the ultra-fineness of grains in ZnS films. -
In this paper, novel device structures in order to realize ultra fast and ultra small silicon devices are investigated using ultra-high vacuum chemical vapor deposition(UHVCVD) and Excimer Laser Annealing (ELA). Based on these fundamental technologies for the deep sub-micron device, high speed and low power devices can be fabricated. These junction formation technologies based on damage-free process for replacing of low energy ion implantation involve solid phase diffusion and vapor phase diffusion. As a result, ultra shallow junction depths by ELA are analyzed to 10~20nm for arsenic dosage(2
${\times}$ 10$\_$ 14//$\textrm{cm}^2$ ), exciter laser source(λ=248nm) is KrF, and sheet resistances are measured to 1k$\Omega$ /$\square$ at junction depth of 15nm and realized sub-50nm n-MOSFET. -
In this paper, we investigated the electrical characteristics through DC power at manufacturing the MIS capacitor insulator AIN thin film based on reactive sputtering method. In case of deposition temperature 250
$^{\circ}C$ , pressure 5mTorr, total flow rate 8sccm(Ar:4sccm N2:4sccm), AIN thin film was deposited with changing DC power. As DC power increses, resistivity is observed a little increase. When AIN thin film is deposited at 100W, the result shows leakage current 10$\^$ -8/A/$\textrm{cm}^2$ at 0.1MV/cm. Otherwise, In case of depositing at 150W and 200W, the result shows that the characteristic of leakage current is under 10$\^$ -9//$\textrm{cm}^2$ at 0.1MV/cm. In C-V characteristic with DC power, deep depletion phenomenon is observed at inversion region in 100W and 150W. In 200W, that phenomenon, however, was showed to decrease. It shows that the hysterisis increases with being increasing DC power. -
In this paper, GaN films have been grown on SiO
$_2$ /Si(100) substrates by RF magnetron sputtering. To obtain high quality GaN films, we used ZnO buffer layer and modified the process conditions. The charateristics of GaN films on RF power, substrate temperature and Ar/N$_2$ gas ratio have been investigated by Auger electron spectroscopy and X-ray diffraction analysis. At RF power 150W, substrate temperature 500$^{\circ}C$ and Ar/N$_2$ =1:2 gas ratio, we could grow high quality GaN films. Through the atomic force microscope and photoluminescence analysises, it was observed that the crystallization of GaN films was improved with increasing annealing temperature and the optimal crystallization of GaN films was found at 1100$^{\circ}C$ annealing temperature. -
GaN thin films on sapphire were grown by rf magnetron sputtering with ZnO buffer layer. The dependence of GaN film quality on ZnO buffer layer was investigated by X-ray diffraction(XRD). The improved film quality has been obtained by using thin ZnO buffer layer. Using Auger electron spectroscopy(AES), it was observed that the annealing process improved the GaN film quality. The surface roughness according to the annealing temperatures(700, 900, 1100
$^{\circ}C$ ) were investigated by AFM(atomic force microscopy) and it was confirmed that the crystallization was improved by increasing the annealing temperature. Photoluminescence at 8K shows a near-band-edge peak at 3.2eV with no deep level emission. -
Silicon wafers using DRAM devices required for high cleaning technology and this cleaning technology was evaluated by defect level or electron life time. This paper examined the correlation of SPV(Surface Photo Voltaic Analyzer) which analyzes diffusion length of minority carriers and DLTS(Deep level Transient Spectroscope) which analyzes defect level.
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InSb temperature dependent hall effect of multilayerd structures were investigated. According to variation of magnetic field measured hall coefficient, Hall mobility, carrier density and hall voltage. For the measurement of electrical properties of hall device, evaperated InSb thin film fabricated with series and parallel multilayers. We found that the XRD analysis of InSb thin film showed good properties at 200
$^{\circ}C$ , 60 minutes. Resistance of ohmic contact increased linearly due to increasing current. Some of device fabrication technique and analysis of Hall effect were discussed. -
Inner part of FRP specimen was made unidirectionally by pultrusion method and outer part of FRP was made by filament winding method to study the effect of fiber orientatons on the strength of FRP. The strength of bending and compression was simulated and evaluated. The results of simulated strength and evaluated strength were different greately each other. The stress which affect the feature of FRP was simulated to investigate the difference of the results between simulation and evaluation Shear stresses were investigated to the main stress to affect the fracture of FRP.
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Generally, hanger insulator for polymer arrestor have to be good insulation properties and mechanical strength and weatherability, But many remark and repairs have been to think about low cost and light weight. The Paper is used Polymer arrestor for post and performance analysis and mechanical strength insulator hanger according to development of simplest product. To enhance the efficiency of experimental modal analysis, we proposed the process which is the selection of the locations and the number of measurement points for pre-test.
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In the previous work, the effect of blending with two kinds of low density polyethylene (LDPE) on physical and electrical properties have been investigated. From the results, blending with two kinds of LDPE was effective method on changing the morphology of LDPE and improving the high-field characteristics in high temperature region. Especially, it suggested that the F
$\_$ BImp/ was associated with the changes of the crystal size. In this work, the relationship between the morphology and the high-field characteristics of blended LDPE was discussed. In addition, the physical and electrical properties of blended LDPE with extrusion treatment were investigated. The two groups of specimen were prepared; Group 1 was prepared by passing 1 time through the extruder included in the film-blowing process, and Group 2 was prepared by passing 2 times through the extruder. From the relation between the crystal size which was perpendicular to the (020) plane and the F$\_$ BImp/ of blended LDPE, it was confirmed that the F$\_$ BImp/ was associated with the changes of crystal size due to the blending. Moreover, the F$\_$ BImp/ of blended LDPE in Group 2 was higher than that of blended LDPE in Group 1. The crystal size of the (020) plane became smaller according to the extrusion treatment. These results suggest that the uniform distribution and dispersion of crystalline occurred due to the extrusion treatment and the morphological change due to the extrusion treatment influenced on the electrical properties of blended LDPE. -
In this paper, we evaluated the effect of accumulated charges on hydrophobicity of room temperature vulcanized(RTV) silicone rubber, which could improve the contamination performance of porcelain insulators, with uv radiation time. Outdoor insulating material could be charged by the corona discharge on field intensified area of insulator and discharge between the water drops. In addition, we performed the accelerated uv radiation on samples and investigated the change of charging decay with time. In this results, it is found that silica-like structure on the surface of RTV silicone rubber was formed by uv treatments and this layer have the characteristic of retaining the charges on surface for a long time. These charges have effects on its hydrophobicity and so adversely effects on contamination performance. Based on our results, we discussed the other degradation mechanism with well known ones.
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22.9 kV CV power cable is very important factor of underground distribution power line. Cyclic aging for 14days is performed to remove a large amount of the volatiles found in freshly manufactured cable. In this paper, we examined AC breakdown characteristics of CV power cable before and after cyclic aging for 14days. As the result, even if there were some exceptions, the AC breakdown voltage before aging was lower than that after aging, but most of the results were that the AC breakdown voltage after aging was lower than that before aging.
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Molybdenum disilicide is widely used for manufacturing high-temperature heating elements owing to its low electrical resistivity, good thermal conductivity, and ability to withstand oxidation at high temperatures. MoSi
$_2$ heating elements with 4-5wt% of montmorillonite type bentonite as plasticzer and a small amount of Si$_3$ N$_4$ , ThO$_2$ , and B as additives was manufactured. Extruded rods of 3.7mmø and 6.7mmø diameter and 400mm long were fabricated using a vacuum extruder, which were then sinrered for 4-5 hrs. at the max. temperrature of 140$0^{\circ}C$ . After 10 minute's oxidation treatment, the diameter of the rod is reduced. The heating elements thus prepared was stable at 1$700^{\circ}C$ and the physical properties such as specific electrical resistivity, hardness, apparent densisty, thermal expansion coefficient, and bending strength were almost identical with thoes of commercial heating elements. In this study we have tried to gain the practical knowledge of manufacturing MoSi$_2$ heating elements so that it may be utilized later in a research of pilot scale and eventually be transferred to industry. -
To investigate the magnetic field distribution of power line, we used amorphous wire sensor. And we discuss extremely low frequency magnetic field distribution dependent upon arrangement of power line and shielding pipe made from iron or alumimum materials by both measurement and FEM(Finite Element Method) analysis. Appling current of single phase 60 [Hz] 15 [A] is supplied to copper wire coated enamel resign. As the results, we confirmed that linear characteristics of amorphous wire sensor is very excellent and measurement value agrees with FEM calculation. Magnetic field distribution due to shielding materials is changed by permeability and conductivity.
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Bi
$_2$ Sr$_2$ CuO$_{x}$ thin films have been fabricated by atomic layer-by-layer deposition using ion beam sputtering(IBS) method. During the deposition, 10 and 90 wt%-ozone/oxygen mixture gas of typical pressure of 1~9$\times$ 10$^{-5}$ Torr are supplied with ultraviolet light irradiation for oxidation. XRD and RHEED investigations reveal out that a buffer layer with some different compositions is formed at the early deposition stage of less than 10 units cell and then Bi-2201 oriented along the c-axis is grown.n. -
The effect of the superconducting film thickness on the substrate temperature has been investigated. Superconducting YBCO thin films have been grown on MgO substrates by pulsed laser deposition. The dependence of the orientation of YBCO film on thickness has been investigated by X-ray diffraction technique. X-ray diffraction indicated that the film orientation was changed by increasing the film thickness and by changing the substrate temperature.
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Sho, Dea-Wha;Li, Yingmei;Cho, Yong-Joon;Kim, Tae-Wan;Korobova, N.;Isaikina, O.;Mansurov, Z.;Baydeldinova, A.;Ksandopoulo, G. 620
The peculiarities of using Self-propagating High-temperature Synthesis (SHS) and solid state phase synthesis for production of high temperature superconductor materials are discussed. Oxide superconductors with general formula$ReBa_2$ $Cu_3$ $O_{7-x}$ (Re= Y, Yb, Sm, Nd) have been made with using barium oxide initial powder instead of traditional barium carbonate. X-ray powder diffraction showed a single phase orthorhombic perovskite structure was produced in all reactions. Phenomena observed during the grinding of the reactant mixture are presented. Mechano-chemical activation - as a pretreatment of the reactant mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product. -
Two kinds of Nd
$_{1+x}$ Ba$_{2-x}$ Cu$_3$ O$_{7-{\delta}}$ , the sintering samples and zone melting samples, were heat treated under pure Ar at 95$0^{\circ}C$ . The substitution of Nd ion for Ba ion in the Nd$_{1+x}$ Ba$_{2-x}$ Cu$_3$ O$_{7-{\delta}}$ before and after the heat treatment were investigated by XRD. In order to know the effects of the heat treatment, the T$_{c}$ and J$_{c}$ of samples with the heat treatment and those without the heat treatment by Ar were comparatively studied. The results show that the substitution of Nd for Ba decreased, T$_{c}$ , and J$_{c}$ increased after the treatment under Ar at 95$0^{\circ}C$ . The Nd$_{1+x}$ Ba$_{2-x}$ Cu$_3$ O$_{7-{\delta}}$ samples were oxygenated under pure oxygen at 30$0^{\circ}C$ . From the XRD pattern it was found that the sample with x< 0.4 could transfer from tetragonal phase to orthorhombic phase after the oxygenation, but the sample with x>0.4 could not make the phase transition even after a long time oxygenation.ion even after a long time oxygenation.ation.n.ation.ation. -
Current lead is one of the first proposed devices for the application of High Temperature-Superconductor(HTSC). The current lead provides high current for electrical machine using superconductor from room temperature. Its characteristics that is zero resistance and low heat transfer rate under critical temperature lead to research for the replacement of existing current lead with HTSC. In this paper, we investigated the temperature distributions of stacking type and rod type current lead with each cross-section area and length using Nastran program and compared each temperature distribution. It is obtained from this paper that stacking type current lead has flat temperature gradient and than rod type one and more stable operation as current lead is closely related with its cross-section area and length.
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Microcrystalline Si films have been deposited by using five W-wire filaments of 0.5 mm diameter for hot-wire chemical vapor deposition (HWCVD). We compared the HWCVD grown films with the film exposed to transformer couple plasma system for the modification of seed layer. W-wire filament temperature was maintained below 1600
$^{\circ}C$ to avoid metal contamination by thermal evaporation at the filament. Deposition conditions were varied with H$_2$ dilution ratio, with and without plasma treatment. From the Raman spectra analysis, we observed that the film crystallization was strongly influenced by the H$_2$ dilution ratio and weakly depended on the distance between the wire and a substrate. We were able to achieve the crystalline volume fraction of about 70% with an SiH$_4$ /H$_2$ ratio of 1.3%, a wire temperature of 1514$^{\circ}C$ , a substrate separation distance of 4cm, and a chamber pressure of 38 mTorr. We investigated the influence of${\mu}$ c-Si film properties by using a plasma treatment. This article also deals with the influence of the H$_2$ dilution ratio in crystallization modification. -
InGaN/GaN multiple quantum wells (MQWs) grown with various growth interruptions between the InGaN well and GaN barrier by metal-organic chemical vapor deposition were investigated using photoluminescence, high-resolution transmission electron microscopy, and energy filtered transmission electron microscopy (EFTEM). The luminescence intensity of the MQWs with growth interruptions is abruptly reduced compared to that of the MQW without growth interruption. Also, as the interruption time increases the peak emission shows a continuous blue shift. Evidence of indium clustering is directly observed both by using an indium ratio map of the MQWs and from indium composition measurements along an InGaN well using EFTEM. The higher intensity and lower energy emission of light from the MQW grown without interruption showing indium clustering is believed to be caused by the recombination of excitons localized in indium clustering regions and the increased indium composition in these recombination centers.
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Perdeuterated hexaflouroacetylacetonato-ytterbium [Yb(SOL-D)
$_3$ ] complexes were synthesized by the keto-enol tautomerism reaction of Yb(SOL-H)$_3$ in methanol-d$_4$ in order to reduce the radiationless transition to the ligands. The luminescence properties of Yb(SOL-D)$_3$ complex were measured in the following anhydrous deuterated organic solvents ; Methanol-d$_4$ , THF-d$_{8}$ , PO(O$CH_3$ )$_3$ and DMSO-d$_{6}$ . The intensity, lifetime and quantum efficiency of the luminescence in DMSO-d$_{6}$ were superior to those in other deuterated solvents. It was suggested that the anhydrous DMSO-d$_{6}$ might be the most appropriate solvent for the liquid laser material of Yb(SOL-D)$_3$ complex.complex. -
Amorphous As-Ge-Se-S thin films have been studied with the aim of identifying optimum etching condition which can be used to produce holographic grating structure for use as diffractive optical elements. In this study, holographic gratings have been formed using He-Ne laser(632.8nm), and fabricated by the method of wet etching using NaOH etchant with various concentration(0.26N, 0.33N, 0.40N). The diffraction efficiency was obtained by +1st order intensity of the diffracted beam. The formed grating profiles were observed by atomic force microscope and showed that the expected grating profile could be achieved by controlling the etching time. Over-etching resulted in under-cutting of the grating lines. The highest 1st order diffraction efficiency for these gratings was about 5.05%.
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We studied about luminance characteristics of blue organic electroluminecent device as thickness ratio. The device is fabricated TPD(N,N'-dyphenyl-N-N'-bis(3-methyphenyl) -1,1'-biphenyl-4,4'-diamine) as hole transport layer and Butyl -PBD(1,1,4,4-Tetraphenyl-1,3-butadiene) as emission layer and electron transport layer. Total thickness is 1000
${\AA}$ as HTL and ETL, each devices has 500${\AA}$ :500${\AA}$ . 400${\AA}$ :600${\AA}$ and 600${\AA}$ :400${\AA}$ of TPD : Butyl-PBD. We obtained the maximum brightness about 175cd/㎡ 500${\AA}$ : 500${\AA}$ thickness devices as HTL:ETL -
In this paper, I have studied minimization of the kerf-width and surface burning which are occurred after the singulation process of multi layer
$\mu$ -BGA( thickness 1.1 mm, 0.9 mm) with a pulsed Nd:YAG( = 532 nm, repetition rate = 10 Hz) laser. The thermal energy of a pulsed Nd:YAG laser is used to cut the copper layer. I have studied are minimization of the surface burning and kerf-width using a photo resist,$N_2$ blowing and polyester double sided tape as a cutting parameter. The$N_2$ blowing reduces a laser energy loss by debris and suppresses a surface carbonization. Also, I have studied characters of cutting with a choice of side of laser beam incidence. The SEM(Scanning Electron Microscope), non-contact 3D inspector and high-resolution microscope are used to measure kerf width and surface state. The optimum value of 1.1 mm$\mu$ -BGA singulation is 524$\mu$ m that is reduced kerf width of 60 % with$N_2$ blowing. And I obtained reduction of carbonization of 68 % with a polyester double side tape in 0.9 mm$\mu$ -BGA. I used laser intensity of 1.91$\times$ 10$^{6}$ /$\textrm{cm}^2$ in this study. -
We investigated the residual DC in the in-plane switching (IPS)-liquid crystal display(LCD) by voltage-transmittance (V-T) hysteresis method. Several IPS-LCD which have different concentrations of cynao LCs and different resistivities of fluorine LCs were fabricated. We found that the residual DC voltage of the IPS-LCD was decreasing with increasing concentration of cyano LCs and increasing with decreasing specific resistivity of fluorine LC materials. The residual DC voltage property can be improved by low molecular weight and high polarity of cyano LC.
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The devices of BST thin films to composite (Ba
$\_$ 0.7/ Sr$\_$ 0.3/)TiO$_3$ using sol-gel method were fabricated by changing of the depositing layer number on Pt/Ti/SiO$_2$ /Si substrate. The thin film capacitor to be ferroelectric devices was investigated by structural and electrical properties. The thickness of BST thin films at each coating numbers 3, 4 and 5 times was 2500[${\AA}$ ], 3500[${\AA}$ ], 3800[${\AA}$ ]. The dielectric factor of thin film when the coating numbers were 3, 4 and 5 times was 190, 400 and 460 on frequency 1[MHz]. The dielectric loss of BST thin film was linearly increased by increasing of the specimen area. -
A flat-type L
$_1$ -B$_{8}$ Mode Ultrasonic motor(USM) uses longitudinal-bending multi-mode vibrator which is constructed with the metal-piezoceramic composite thin plate vibrator. Especially, the characteristics of vibrating displacement of the vibrator are important for the fabrication of USM. So, in this study, we tried to analyze them by the FEM(finite element method) simulation program. ANSYS 5.6 we used is a finite element software enabling the analysis of 2 or 3 dimensional structure of piezoelectric materials. Using this made us analyzing the resonance frequency and calculating displacement of vibrator and then the position of the projection.n. -
The Sr
$\_$ 0.8/Si$\_$ 2.4/Ta$_2$ O$\_$ 9/(SBT) thin films are deposited on Pt-coated electrode(Pt/TiO$_2$ /SiO$_2$ /Si) using RF magnetron sputtering method. With increasing post-annealing temperature from 600[$^{\circ}C$ ] to 850[$^{\circ}C$ ], Bi-layered perovskite phase was crystallized above 650[$^{\circ}C$ ]. The maximum remanent polarization and the coercive electric field is 11.60[${\mu}$ C/$\textrm{cm}^2$ ], 48[kV/cm] respectively. The leakage current density of SBT capacitor at post-annealing temperature of 750[$^{\circ}C$ ] is 1.01${\times}$ 10$\^$ -8/ A/$\textrm{cm}^2$ at 100[kV/cm]. The fatigue characteristics of SBT thin films did not change up to 10$\^$ 10/ switching cycles. -
The Sr
$\sub$ 0.8/Bi$\sub$ 2.4/Ta$_2$ O$\sub$ 9/(SBT) thin films are deposited on Pt-coated electrode(Pt/TiO$_2$ /SiO$_2$ /Si) using RF magnetron sputtering method. With increasing annealing tempera ture from 600[$^{\circ}C$ ] to 850[$^{\circ}C$ ], Bi-layered perovskite phase was crystallized above 650[$^{\circ}C$ ]. The maximum remanent polarization and the coercive electric field is 11.60[${\mu}$ C/$\textrm{cm}^2$ ], 48[kV/cm] respectively. The dielectric constant and leakage current density is 213, 1.01${\times}$ 10$\^$ -8/ A/$\textrm{cm}^2$ respectively at annealing temperature of 750[$^{\circ}C$ ]. -
A low-temperature cofired-ceramic (LTCC) multi-layer ceramic (MLC) band-pass filter (BPF) is presented, which has the benefits of low cost and small size. The BPF is designed for a IMT-2000 handset. The computer-aided design technology is also presented. The BPF with an attenuation pole at below the passband has been discussed and realized. The equivalent circuit of the BPF was established by transmission lines and lumped capacitors. The frequency characteristics of the LTCC-MLC BPF is well acceptable for IMT-2000 application.
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The output characteristics of step-down piezoelectric transformer is changed by a structure of layers. In this paper, we simulated output characteristics of multi-layer piezoelectric transformers with variation of output layers. Also, fabricated piezoelectric transformers were compared with simulated data. From simulated piezoelectric transformers, the output voltage decreased with increasing number of layers. From these results, piezoelectric transformers were made and the output electrical power of the transformers was measured at resonance frequency and at other frequency. The electrical power of transformers was measured on each transformer's resonance mode. However, measured value of 12-layed transformer's output power was smaller than that of 6-layered transformer's one. It is supposed that internal capacitance and reactance of the piezoelectric transformer's were effected in this result. Therefore we need to connect other road resistance and capacitance in output circuit, in order to increase electrical power of transformers.
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The structural, piezoelectric and dynamic range characteristics of modified PbTi
$O_3$ ceramics were investigated as a function of Mn$O_2$ addition. With the increase of Mn$O_2$ addition, Curie temperature was decreased. As the increase of Mn$O_2$ addition, mechanical quality factor ($Q_{mt3}$ ) in the third over tone thickness mode was increased. Dynamic range in the third over tone thickness mode was also increased with the increase of Mn$O_2$ addition. The composition ceramics added to 0.075wt% Mn$O_2$ showed the best properties for SMD type resonator using third over tone thickness vibration in terms of high Curie temperature more than 31$0^{\circ}C$ and dynamic range of 49.38dB.B. -
In this paper, the pizoelectric and dielectric properties of 0.95Pb(ZrxTil-x)O
$_3$ - 0.05Pb(Mn$\_$ 0.2/Fe$\_$ 0.4/W$\_$ 0.4/)O$_3$ piezoelectric ceramics is investigated as a function of Zr/Ti mole ratio. Also, MPB(Morphotropic Phase Boundary) and optimal sintering temperature is studied using XRD and SEM. As a results, when Zr/Ti mole ratio is 52/48, electromechanical coupling factor, k$\_$ p/, is 58[%], permittivity,$\varepsilon$ $\^$ T/$\_$ 33//$\varepsilon$ 0, is 1360 and piezoelectric strain constant, d$\_$ 33/ is 265[pC/N] and the piezoelectric and dielectric properties become maximum. Phase transition temperature of its ternary piezoelectric system is about 350[$^{\circ}C$ ]. From the XRD analysis, when Zr/Ti mole ratio is 52/48, tetragonal phase transits to rhombohedral phase. Also, From measuring results of the sintering density, when sintering temperature is 1050[$^{\circ}C$ ], sintering density become maximum and is about 7930[kg/㎥], and average grain size is about 2-3[$\mu\textrm{m}$ ]. -
The (Ba
$_{0.3}$ Bi$_{0.3}$ Sr$_{0.4}$ )TiO$_3$ [BBST] ceramics were prepared by conventional mixed oxide method. The structural properties of the BBST ceramics with sintering temperature were investigated by XRD, SEM, EDS. In the case of BBST ceramics sintered at 1150~135$0^{\circ}C$ , the$Ba_{0.5}$ Sr$_{0.5}$ TiO$_3$ and SrBi$_4$ Ti$_4$ O$_{15}$ phase were coexisted. The 2$\theta$ value of the BST (110) peaks were shifted to the lower degree at the sintering temperature of 130$0^{\circ}C$ and 135$0^{\circ}C$ . The grains of the BBST ceramics sintered at 130$0^{\circ}C$ and 135$0^{\circ}C$ were not appeared. Increasing the sintering temperature, the densities of the BBST ceramics were increased. In the BBST ceramics sintered at 130$0^{\circ}C$ and 135$0^{\circ}C$ , the mole ratio of Bi was decreased.d.ed.d.d.d. -
In this paper, the structural and electrical properties of the Sr
$_{1-x}$ Ca$_{x}$ TiO$_3$ (0$\leq$ x$\leq$ 0.2) (0$\leq$ r$\leq$ 0.2)-based grain boundary layer ceramics were investigated by X-ray, SEM and V-I system. Increasing the Ca content, the average grain size and the lattice constant were decreased. The relative density of all specimens was >96%. The 2nd phase formed by thermal diffusing from the surface lead to a very excellent electrical properties, that is,$\varepsilon$ $_{r}$ >50000, tan$\delta$ <0.05,$\Delta$ C<$\pm$ 10%.\pm$ 10%.%. -
The dielectric and sintering properties of LaAlO
$_3$ ceramics synthesised with La$_2$ O$_3$ -Al$_2$ O$_3$ (LAO) and La$_2$ O$_3$ -Al(OH)$_3$ (LAH) were investigated. In case of LAH samples, a single phase of LaAlO$_3$ powders was formed at 100$0^{\circ}C$ , density of the ceramics sintered at 140$0^{\circ}C$ was 6.41g/㎤, and the dielectric constant and loss were 22.4 and 0.003, respectively. In case of LAO samples, a single phase of LaAlO$_3$ powders was formed at 130$0^{\circ}C$ , density of the ceramics sintered at 150$0^{\circ}C$ was 6.35g/㎤, and the dielectric constant and loss were 22.16 and 0.009, respectively. -
The effect of grinding on the synthesis of LaAO
$_3$ ceramics was investigated. The mixture ground by plantary ball mill showed 70nm particle size (wet ball mill or unground=0.5$\mu$ m). Monophase LaAlO$_3$ powders were formed when ground samples were heated at 100$0^{\circ}C$ , however unground samples required temperatures above 130$0^{\circ}C$ . Density of the ground samples sintered at 140$0^{\circ}C$ showed 98.3% of theoretical density (unground=93.5% at 150$0^{\circ}C$ ). Dielectric constant of the ground samples($\varepsilon$ r=22.4) showed higher values than that of the unground samples($\varepsilon$ r=20.32). Temperature coefficient of capacitance($\tau$ $_{c}$ ) and dielectric loss (tan$\delta$ ) of the ground samples were similar to those of unground samples.s. -
The effects of post annealing temperature by the Rapid Thermal Annealing(RTA) on the electrical properties of Pb(Zr,Ti)O
$_3$ (PZT) thin film were investigated. Analyses by the RTA treatments reveled that the leakage current of PZT thin films strongly depend on heating temperature and time. It was found that leakage current properties of PZT capacitor were changed by heating temperature during the RTA annealing. On Pt/Ti/Si substrates, PZT films are deposited at 350$^{\circ}C$ by rf magnetron sputtering. The X-ray diffusion (XRD) was confirmed the formation of PZT thin film. Leakage current characteristics were improved with decreasing the post annealing temperature of PZT thin film. RTA annealed film on the 700$^{\circ}C$ shows ferroelectric and electrical properties with a remanent polarization of 12.4${\mu}$ C/$\textrm{cm}^2$ coercive field of 117kV/cm, leakage current J= 6.2${\times}$ 10$\^$ -6/ A/$\textrm{cm}^2$ -
In many papers, the electrochemical analysis of LiMn
$_2$ O$_4$ shows the transition results of Mn$^{3+}$ ion. Charge ordering is accompanied by simultaneous orbital ordering due to the Jahn-Teller effect in Mnl$^{3+}$ ions. To analyze the cycle performance of LiMn$_{2-x}$ Cu$_{x}$ O$_4$ as the cathode of 4 V class lithium secondary batteries, XRD, TGA analysis were conducted. Although the cycle performance of the LiMn$_{2-x}$ Cu$_{x}$ O$_4$ was improved from pure LiMn$_2$ O$_4$ , the discharge capacity was significantly lower than LiCoO$_2$ . In this paper, We study the Electrochemical characterization and enhanced stability of Cu-doped spinels in the LiMn$_{2-x}$ Cu$_{x}$ O$_4$ upon initial cycling.l cycling. -
Ferroelectric lead ziroconate titanate (PZT) thin film were fabricated on the different bottom electrodes. Both Ru and Ru/RuO
$_2$ bottom electrodes were deposited by RF-magnetron sputteirng method. The structure phase and surface morphology of the PZT thin film were largely affected by the bottom electrode. It was observerd that used of Ru/RuO$_2$ double electrode reduced leakage current and better ferroelectric properties compare with RuO$_2$ bottom electrode. From these results, Ru/RuO$_2$ hybride bottom electrode is thought to be the available structure for the bottom electrode. -
In this paper, we present the effect the length the MSL(Microstrip Line) on the oscillation characteristic of the fabricated VCOs(Voltage Controlled Oscillator) designed and analyzed by RF circuit simulator Serenade(ANSOFT Co.) and fabricated by screen printing method on the alumina substrate. We have fabricated VCOs with 3 different MSL length and each MSL length of the VCO is 140mi1, 280mil and 560mi1. The oscillation frequency of each sample(VCO) was tuned to UHF band(750MHz∼900MHz) varying the capacitance. The experimental result shows the phase noise -82∼-97[dBc/Hz] at a 50 [kHz] offset frequency, the pushing figure 94∼318[kHz] at 3
${\pm}$ 0.15[V] and the harmonics 13∼21 [dBc] between MSL length 140mi1s and 560mi1. The frequency and output variation width are 779∼898[MHz], -36∼-33[dBm] at MSL length 140mi1; 818∼836[MHz], -27.19∼-27.06[dBm] at 280mi1;751.54∼751.198[MHz],-33.44∼ -33.31[dBm] at 560mi1. we examined 3 VCOs oscillation characteristic difference through comparison with phase noise, oscillation power and frequency by control voltage change, harmonics and pushing figure for each sample. -
We have fabricated thin films using the DC/RF magnetron sputtering of 74wt%Ni-l8wt%Cr-4wt%Al-4wt%Cu alloy target and studied the effect of the process parameters on the electrical properties for low TCR(Temperature Coefficient of Resistance) films. In sputtering process, pressure, power and substrate temperature, are varied as controllable parameter. The films are annealed to 400
$^{\circ}C$ in air and nitrogen atmosphere. The sheet resistance, TCR of the films increases with increasing annealing temperature. It abruptly increased as annealing temperature increased over 300$^{\circ}C$ in air atmosphere. From XRD, it is found that these results are due to the existence of NiO on film surface formed by annealing. As a results of them, TCR can be controlled by variation of sputter process parameter and annealing of thin film. -
In this study, the effect of oxygen partial pressure on the electrical properties of vanadium oxide(VO
$_{x}$ ) thin films were investigated. The thin films were prepared by r.f. magnetron sputtering from V$_2$ O$_{5}$ target in a gas mixture of argon and oxygen. The oxygen partial pressure ratio is changed from 0% to 8%. I-V characteristics were distinguished between linear and nonlinear region. In the low field region the conduction is due to Schottky emission, while at high fields it changes to Fowler-Nordheim tunneling type conduction. The conductivity measurements have shown an Arrhenius dependence of the conductivity on the temperature.ure. -
Instead of a solution technigue producing amorphous LiV
$_3$ O$_{8}$ form, we prepared Lithium vanadate glass by melting Li$_2$ O-P$_2$ O$_{5}$ -V$_2$ O$_{5}$ , composition in pt. crucible and by quenching on the copper plate. From the crystallization of Li$_2$ O-P$_2$ O$_{5}$ -V$_2$ O$_{5}$ , we could abtain crystal phase, LiV$_3$ O$_{8}$ . The material heat-treated at lower-temperature, 25$0^{\circ}C$ was less crystalline, but had higher capacity. In present paper, we describe eletrochemical properties during crystallization process and find the best crystallization condition of Li$_2$ O-P$_2$ O$_{5}$ -V$_2$ O$_{5}$ glass as cathod material.cathod material. -
This paper describes the fabrication and characteristics of CrN thin-film type pessure sensors, which the sensing elements were deposited on SUS. 630 diaphragm by DC reactive magnetron sputtering in an argon-nitride atmosphere(Ar-(10%)N
$_2$ ). The optimized condition of CrN thin-film sensing elements was thickness range of 3500${\AA}$ and annealing condition(300$^{\circ}C$ , 3 hr) in Ar-10 %N$_2$ deposition atmosphere. Under optimum conditions, the CrN thin-films for strain gauges is obtained a high resistivity,$\rho$ =1147.65${\mu}$ $\Omega$ cm, a low temperature coefficient of resistance, TCR=-186 ppm/$^{\circ}C$ and a high temporal stability with a good longitudinal, 11.17. The output sensitivity of fabricated CrN thin-film type pressure sensors is 2.36 mV/V, 4∼20 mA and the maximum non-linearity is 0.4 %FS and hysteresis is less than 0.2 %FS. -
This paper described on the fabrication of microstructures by DRIE(Deep Reactive Ion Etching). SOI(Si-on-insulator) electric devices with buried cavities are fabricated by SDB technology and electrochemical etch-stop. The cavity was fabricated the upper handling wafer by Si anisotropic etch technique. SDB process was performed to seal the fabricated cavity under vacuum condition at -760 mm Hg. In the SDB process, captured air and moisture inside of the cavities were removed by making channels towards outside. After annealing(1000
$^{\circ}C$ , 60 min.), the SDB SOI structure was thinned by electrochemical etch-stop. Finally, it was fabricated microstructures by DRIE as well as a accurate thickness control and a good flatness. -
We synthesized polypyrrole (PPy) by electrolysis of the pyrrole monomer solution containing support electrolyte KCl and/or p-toluene sulfonic acid sodium salt (p-TS). The electrochemical behavior was investigated using cyclic voltammetry and AC impedance. In the case of using electrolyte p-TS, the redox potential was about -0.3 V vs. Ag/AgCl reference electrode, while the potential was about 0 V for using electrolyte KCl. It is considered as the backbone forms a queue effectively by doping p-T S. Therefore, it is possible to be arranged regularly. That leads to improvement in the electron hopping. The AC impedance plot gave a hint of betterment of mass transport. PPy doped with p-TS has improved in mass transport, or diffusion. That is because the PPy doped with p-TS has a good orientation, and is more porous than PPy with KCl.
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Very fine cobalt oxide xerogel and ambigel powder were prepared using a unique solution chemistry associated with the sol-gel process. The mesoporous structure of the initial gel is maintained by removing fluid under conditions where the capillary forces that result extraction are either low or no existent, are either low or nonexistent. Controlling both the pore and solid architecture on the nanoscale offers a strategy for the design of supercapacitor. The results materials determine by using electrode that mixed ketjen black and PVdF. But CoO
$\_$ x/ have the low voltage, so we experimente to change electrolyte and various concentration. -
This research made a study of MnO
$_2$ electrode for supercapacitor with a diffuser (Polyvinyl alcohol). Manganese dioxide was used as active material. We tried to increase specific surface area by adding PVA. Manganese dioxide was synthesized by a sol-gel method using fumaric acid and oxalic acid in low temperature with high yield. Therefore, We prepared Manganese dioxide powder. This powder was used by active materials. The electrode was made by a mixture of active material, ketjen-black which is a large specific surface area, and PVdF-co-HFP as binder agent with using Nickel mesh as current collector. Here we reported on the synthesis and electrochemical performance of a enhanced material. All active materials have been submitted to X-ray diffraction and Scanning electron microscopy. -
We have used the random fluidic self-assembly (RFSA) technique based on the chip pattern of hydrophobic self-assembly layers to assemble microfabricated particles onto the chip pattern. Immobilization of DNA, fabrication of the particles and the chip pattern, arrangement of the particles on the chip pattern, and recognition of each using DNA fluorescence measurement were carried out. Establishing the walls, the arrangement stability of the particles was improved. Each DNA is able to distinguish by using the lithography process on the particles. Advantages of this method are process simplicity, wide applicability and stability. It is thought that this method can be applicable as a new fabrication technology to develop a minute integration type biosensor microarray.
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Dendrimers represent a new class of synthetic macromolecules characterized by a regularly branched treelike structure. Dendrimer can be made with high regularity and controlled molecular weight. Peculiar features of the dendritic geometry are the large number of end groups as well as the shape persistence in higher generations, approaching spherical geometry. One of the most peculiar characteristics of dendritic macromolecules is their controlled molecular structure and orientation, which means that they have a practical application in achieving a highly organized molecular arrangement. We attempted to fabricate a G4-48PyA dendrimer LB films containing 48 pyridinealdoxime functional end group that could form a complex structure with metal ions. Also, we investigated the surface activity of dendrimer films at air-water interface. And we have studied the electrical properties of the ultra-thin dendrimer LB films. The electrical properties of the ultra-thin dendrimer LB films were investigated by studying the current-voltage(I-V) characteristics of metal/dendrimer LB films/metal (MIM) structure. And rectifying behavior of the devices was occurred in applied field.
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Because using LB method, result that produce Arachidic acid and Stearic acid LB film and measure the accumulation characteristic and electrical characteristic is as following. Organic monolayers of surface of the water compression each 9 layer's LB film to slide glass and manufactured MIM device compressing molecular film only. Could confirm that accumulation was good seeing as absorption coefficient and SEM picture, AFM picture that prevent manufactured LB films. Formation of domain of coexistence form that prevent LB film is indefinite and distinction of border side was not clear, and could know that roughness appears greatly. Obtained current by applied voltage could know that is proportional almost, though Arachidic acid appeared as bulk of current that happen in equaler certification voltage than Stearic acid is less, this alkyl chain longer Arachidic acid that serving relations special quality is superior know can .
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Non-contacting capacitive sensor, based on principle of the cross capacitor, for measuring of
$\mu\textrm{m}$ -order displacements have been fabricated and characterized. To overcome disadvantages of the existed capacitive sensors of parallel type with 2-electrodes and 3-electrodes, the developed new sensor was designed to have 4-electrodes, two of them used high and low electrode the other two used as guard electrodes, on a sapphire plate with diameter 17 mm and thickness 0.7 mm, and are symmetrically situated with a constant gap of 0.2 mm between the electrodes. This sensor can be used for measuring the distance between sensor and target not only the metallic but also non-metallic target without ground connection. -
This paper investigated that resonant frequencies of microstrip patch antenna were frequency aigle when PZT were used as the antenna substrates. The resonant frequencies of the antenna using the piezoelectric substrate were able to be controlled by applied voltage. The frequency variation of the air gap antenna was 16MHz when the voltage variation was 12[KV/cm].
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The main objective of this paper is to design and mechanical strength analysis of UHV(Ultra High Voltage) suspension insulator. One of the important properties required for suspension insulators is mechanical strength under tensile load. The cement and porcelain part are express according to change of pin head type an aspect mechanical stress. These insulators are designed and produced by using the computer analysis of mechanical, electrical and electrical stresses together with the technical know-how accumulated from long years of study into every respect of insulators.
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The mold transformer has anti-burnt and possibility of small size contrary to oil-immersed transformer. The mold transformer has generally cooling duct between low voltage coil and high voltage coil and also made by one body molding for small size and low loss. In this paper, the temperature distribution of designed 50kVA pole mold transformer for power distribution is investigated by FEM program. The designed transformer is also manufactured and temperature rise test is carried out.
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Recently deep interests and attractions have been paid on the generation of ozone, which is widely used to remove bad smell and to clear water. Silent discharge is considered as one of the most effective methods to generator ozone. In this paper, silent discharge reactors were made, waich were filled with different dielectric materials, and some silent discharge charactistics were investigated experimantaiiy.
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Polymer bushing used for overhead line switch was designed and investigated. Requirements of electrical ratings such as partial discharge, ac withstand voltage, impulse voltage and material properties were proposed in accordance with IEEE 386 and pre-standard (PS) 151-146∼147, 170∼180 of KEPCO. The polymer bushing consists of an internal epoxy bushing and external housing made of EPDM rubber. The rubber housing was molded with mold cone. Therefore, the polymer bushing offers several advantages like light weight, good sealing properties, easy installation and excellent performance in contamination. Electric field analysis was also introduced in order to verify the reliability of the design.
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We described a method resonant mode identification in dielectric-disc loaded cylindrical cavity resonators. The characteristic equation is solved by using the ContourPlot graph of Mathematica. Contour graph method uses graphical method. It is comparable with numerical method. The numerical method is very difficult a mode identification. The analysis based on the approximated electromagnetic representation. This kinds of studies only concentrated on the calculation of resonant frequencies, and a mode identification of resonant frequencies have not been covered. But, the contour graph method to analyze the characteristic equations is simple and all parts of resonant frequency graph can be easily drawn, it is possible to calculate precise resonant frequencies and to identify the mode of resonant frequencies.
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This paper presents an improved automatic vending machine for ices. Specially, the main topic of this paper is the development of moving parts for carrying ices out of a freezer. In general, carrying ices out of a vending machine causes much cool air losses. The developed vending machine reduces much cool air losses by the improvement of moving parts. Also the machine reduces many mechanical troubles caused by the freezing of mechanically moving parts.
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we have investigated a characteristic of a vibration displacement detector, which was made with a photocoupler. Output signals of the detector were dominant at 700Hz of the frequency of vibrator, and It was maximum, when the amplitude of input signal had been at 1.1V. The detector will be used in measuring the surface roughness of substrates.
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Conductive polymer is insulator or semiconductor in initial state. Polyaniline(PANI) is a
$\pi$ -conjugated polymer that shows electric property changes, when it is contact with oxidant/reductor chemicals. Synthesis of polyaniline is used vacuum evaporation method, using by (NH$_4$ )$_2$ O$_{8}$ 과 NMP, NH$_2$ NH$_2$ , HCl, MH$_4$ OH, etc. Doped PANI is used such a resistor, addition to graphite is increased conductivity. Applying contact voltage, samples show constant current and contact temperature.e. -
In this thesis, specimens was manufactured in general method annexing PMB-PZT system ceramic, and the following conclusion has been deduced. In XRD, the crystal structure of ceramic has the tetragonal structure which is close to rombohedral structure, and consequently the specimen characterized by MPB was manufactured. According to dopping with xPMB, electromechanical factor(kp) little is changed. kp was maximum value 23.37[%] at xPMB 0.03[mol%]. mechanical quality factor(Qm) was maximum value 237.04 at xPMB 0.03[mo1%].
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We were fabricated of NiCr thin film resistors on A1
$_2$ O$_3$ and SiO$_2$ /Si substrates by dc magnetron sputtering system. The AC characteristics of resistors were studied. The cut-off frequency were found >10 MHz for the resistors with 39 ohm value of Alumina substrates, but the cut-off frequency were found 400 kHz for the resistors with 168 ohm value of SiO$_2$ /Si substrates. In high frequency applications, the substrate selection is the most important factor. -
In this paper, the dielectric properties of epoxy composites used for transformers are studied. The dielectric permittivity and loss of specimen are measured at the frequency range of 30[Hz]∼1[MHz] about temperature 20[
$^{\circ}C$ ],100[$^{\circ}C$ ] and 140[$^{\circ}C$ ] respectively from a series of experiments. When the filler is added, between epoxy and silica is formed interface. Therefore, observed higher values of dielectric permittivity and loss in filled epoxy are attributed to MWS polarization effect. Also, glass transition temperature was shifted to higher temperature and value of dielectric permittivity and loss were decreased due to 2nd curing. Deformation of interfacial state is improved and value of dielectric permittivity and loss were decreased at low frequency region by the surface treatment of fillers with silane coupling agents. -
This machine is a high-vacuum exhaust sealing device which makes the inside of PDP element in high vacuum state, blows inactive gases into it and finally seals it. This machine consists of vacuuming parts, heating parts and exhausting parts. Applying the energy saving technology, this machine improves the temperature uniformity of vacuuming and heating parts.
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The AgInS
$_2$ epilayers with chalcopyrite structure grown by using a hot-wall epitaxy (HWE) method have been confirmed to be a high quality crystal. From the optical absorption measurement, the temperature dependence of the energy band gap on the AgInS$_2$ /GaAs was derived as the Varshni's relation of Eg(T)=2.1365 eV-(9.89${\times}$ 10$\^$ -3/ eV)T$^2$ /(2930+T). After the as-grown AgInS$_2$ /GaAs was annealed in Ag-,S-, and In-atmosphere, the origin of point defects of the AgInS$_2$ /GaAs has been investigated by using the photoluminescence (PL) at 10 K. The native defects of V$\_$ Ag/, V$\_$ s/, Ag$\_$ int/, and S$\_$ int/ obtained from PL measurement were classified to donors or acceptors type. And, we concluded that the heat-treatment in the S-atmosphere converted the AgInS$_2$ /GaAs to optical p-type. Also, we confirmed that the In in the AgInS$_2$ /GaAs did net from the native defects because the In in AgInS$_2$ did exist as the form of stable bonds. -
A simple and versatile method of manufacturing semiconductor devices with pn-junctions used the silicon direct bonding technology with simultaneous impurity diffusion is suggested . Formation of p- or n- type layers was tried during the bonding procedure by attaching two wafers in the aqueous solutions of Al(NO
$_3$ )$_3$ , Ga(NO$_3$ )$_3$ , HBO$_3$ , or H$_3$ PO$_4$ . An essential improvement of bonding interface structural quality was detected and a model for the explanation is suggested. Diode, Dynistor, and BGGTO structures were fabricated and examined. Their switching characteristics are presented. -
We report the structural and electrical properties of hafnium oxide (HfO
$_2$ ) films with tungsten silicide (WSi$_2$ ) metal gate. In this study, HfO$_2$ thin films were fabricated by oxidation of sputtered Hf metal films on Si, and WSi$_2$ was deposited directly on HfO$_2$ by LPCVD. The hysteresis windows in C-V curves of the WSi$_2$ HfO$_2$ /Si MOS capacitors were negligible (<20 mV), and had no dependence on frequency from 10 kHz to 1 MHz and bias ramp rate from 10 mV to 1 V. In addition, leakage current was very low in the range of 10$^{-9}$ ~10$^{-10}$ A to ~ 1 V, which was due to the formation of interfacial hafnium silicate layer between HfO$_2$ and Si. After PMA (post metallization annealing) of the WSi$_2$ /HfO$_2$ /Si MOS capacitors at 500$^{\circ}C$ EOT (equivalent oxide thickness) was reduced from 26 to 22$\AA$ and the leakage current was reduced by approximately one order as compared to that measured before annealing. These results indicate that the effect of fluorine diffusion is negligible and annealing minimizes the etching damage. -
Ba(Zr
$_{x}$ Ti$_{l-x}$ )O$_3$ (BZT) thin films of x=0.2 and 150nm thickness were prepared on Pt/SiO$_2$ /Si substrate by RF Magnetron Sputtering deposition at several temperature (40$0^{\circ}C$ , 50$0^{\circ}C$ ,$600^{\circ}C$ ). As the substrates temperature increase, crystallization of the films and high dielectric constants can be obtained. Capacitance of the film deposited at high temperature is more sensitive to the applied voltage than that of the film deposited at low temperature, and the film's breakdown voltage is higher in low temperature.ure. -
In this study, temperature dependency of current gain for AlGaAs/GaAs/GaAs HBT is analytically proposed over the temperature range between 300K and 600K. Energy bandgap, effective mass, intrinsic carrier concentration are considered as temperature dependent parameters. Collector current which is numerically calculated is then analytically expressed to enhance the speed of calculation for current gain. From the results, current gain decreases as the temperature increases. These results will be used to expect the unity current gain frequency f
$_{T}$ in conjunction with emitter-base and collector- base capacitances.s. -
In this work, transient characteristics of the Non-Punch Through(NPT) Insulated Gate Bipolar Transistor(IGBT) has been studied. we has analyzed with lifetimes excess minority carrier injected into N-dirft, base region of IGBT's BJT part and accumulated charge of on-state which affected swiching characteristic. In this paper, excess minority carrier and charge distribution in active base region is expressed analytically. This analysis proposed optical trade-off between lifetimes and accumulated charge for decreasing switching losses because charge result in switching loss when device was tuned off.
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In this work, we investigated on the white-colored ribbon fiber synthesized from GaN powder. We convinced the formation of monoclinic phase
$\beta$ -Ga$_2$ O$_3$ from the X-ray diffraction pattern on ribbon fiber. The 10 K PL spectrum consisted with the strong emission band caused by self-activated optical center at 3.464 eV with the full-width at half maximum of 48 meV and the impurity related emission bands. Through this work, the optical properties and the electrical conductivity of$\beta$ -Ga$_2$ O$_3$ , it will be useful for the fabrication of optoelctronic devices operating in visible spectrum region. -
Europium-activated Ga
$_2$ O$_3$ powders were prepared by modified "Pechini method" from mixed aqueous solutions of gallium nitrate, europium nitrate, ethylene glycol and citric acid. The formation process and structure of the phosphor powders were investigated by means of TG/DTA, XRD and SEM. It has been found that the phosphor powders were amorphous up to 50$0^{\circ}C$ and changed into crystalline$\beta$ -Ga$_2$ O$_3$ phase above$600^{\circ}C$ . The resulting nano-sized powders were obtained. Red luminescence in emission spectra were observed at room temperature. -
The stress induced leakage currents of thin silicon oxides is investigated in the VLSI implementation of a self learning neural network integrated circuits using a linearity synapse transistor. The channel current for the thickness dependence of stress current, transient current, and stress induced leakage currents has been measured in oxides with thicknesses between 41
${\AA}$ , 86${\AA}$ , which have the channel width${\times}$ length 10${\times}$ 1${\mu}$ m, 10${\times}$ 0.3${\mu}$ m respectively. The stress induced leakage currents will affect data retention in synapse transistors and the stress current, transient current is used to estimate to fundamental limitations on oxide thicknesses. The synapse transistor made by thin silicon oxides has represented the neural states and the manipulation which gaves unipolar weights. The weight value of synapse transistor was caused by the bias conditions. Excitatory state and inhitory state according to weighted values affected the channel current. The stress induced leakage currents affected excitatory state and inhitory state. -
This study describes a selective Ag etching solution for use with pattern on the surface of copper. This etching solution uses potassium iodide and potassium sulfate as the ligand that coordinates to the metal ions and ferricyanide as the oxidant. The etching rate was depended on the concentration of co-ligands and time. But the etching rate wasn't depended on the pH(2∼6), and oxidant(K
$_3$ Fe(CN)$\_$ 6/). Complete etching of silver can be achieved rapidly within 90sec for 4.46${\mu}$ m thick metal films when aqueous solutions containing K$_3$ Fe(CN)$\_$ 6/, K$_2$ S$_2$ O$\_$ 8/ and KI was used. This etching solution was characteristic of anisotropic etching. -
In this study, RuO
$_2$ thin films were etched in inductively coupled$O_2$ plasma. Etching characteristics of RuO$_2$ thin films including etch rate and selectivity were evaluated as a function of rf power in$O_2$ plasma and gas mixing ratio in$O_2$ /Ar plasma. In$O_2$ plasma, the etch rate of RuO$_2$ thin film increases as rf power increases. In$O_2$ /Ar plasma, the etch rate of RuO$_2$ thin film increases up to 10% Ar, but decrease with furthermore increasing Ar mixing ratio. The enhanced etch rate can be obtained with increasing rf power and small addition of Ar gas. -
In this study, (Ba,Sr)TiO
$_3$ (BST) thin films were etched with a magnetically enhanced inductively coupled plasma(MEICP). Etching characteristics of BST thin films including etch rate and selectivity were evaluated as a function of the etching parameters such as gas mixing ratio, rf power, dc bias voltage and chamber pressure. The maximum etch rate of the BST films was 1700$\AA$ /min at Ar(90)/CF$_4$ (10), 600 W/350 V and 5 mTorr. The selectivity of BST to PR was 0.6, 0.7, respectively. To analyze the composition of surface residue remaining after the etching, samples etched with different CF$_4$ /Ar gas mixing ratio were investigated with X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). From the results of XPS and SIMS, there are chemical reaction between Ba, Sr, Ti and C, F radicals during the etching and remained on the surface. -
The electron drift mobilitity of poly(4,4'-cyclohexylidenediphenyl carbonate)(PC-Z) doped with 3,5-dimethyl-3',5'-di-t-butylstilbenequinone(MBSQ) was measured by the time-of-flight technique. Energy gap of the polymer doped with 25wt% of MBSQ was 3.1 eV. The electron drift mobility was 2.98
${\times}$ 10$\^$ -6/$\textrm{cm}^2$ /V$.$ s at 293K. The electric field and temperature dependences of the electron drift mobility were discussed with Poole-Frenkel and Arrhenius formulations. The activation energy(E$\_$ 0/), Poole-Frenkel coefficient(${\beta}$ ) and effective temperature(T$\_$ eff/) of the mobility are 0.815 eV, 1.73${\times}$ 10$\_$ -4/ eV$.$ cm$\^$ 1/2//V$\_$ 1/2/ and 6.43${\times}$ 10$^2$ K, respectively. -
SOI(Silicon-On-Insulator) technology is proposed as an alternative to bulk silicon for MEMS(Micro Electro Mechanical System) manufacturing. In this paper, we fabricated the SOI wafer with uniform active layer thickness by silicon direct bonding and mechanical polishing processes. Specially-designed electrostatic bonding system is introduced which is available for vacuum packaging and silicon-glass wafer bonding for SOG(Silicon On Glass) wafer. We demonstrated thermopile sensor and RF resonator using the SOI wafer, which has the merits of simple process and uniform membrane fabrication.
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In this paper, we analyzed the characteristics of insulating material with ELB(earth leakage circuit breaker) through tracking experiment and the study was carried out three different types of samples. The tracking is breakdown phenomenon of material surface that is generated on the organic insulating material. The test method applied IEC publication 587. The result of the sample breakdown by tracking was carbonized and resistance of between the electrodes is approximately 300
$\Omega$ . In the result of DSC analysis, the caloric peak was detected before 100$^{\circ}C$ in product of tracking. It appeared weight loss of 10.87% at 537$^{\circ}C$ on TGA. IR spectrum analysis showed carbon-hydrogen(C-H)bond on molecular structure that is the sample of tracking. -
This paper aims to investigate the characteristics of braided thermoplastic composite and pressure relief for polymer arrester. In general, braided composite has potential for improved impact and delamination resistance. Manufacturing processes of the braided composite could also be automated and could potentially lead to lower costs. Therefore, in consideration of characteristics of pressure relief for polymer arrester, the fabric pattern of braided composite was decided. And polymer arrester module was manufactured with braid.
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Silicone rubber is being used for the housing material of outdoor high voltage insulators such as composite insulator, bushing, surge arrestor and cable terminator because of good tracking and erosion resistance, good hydrophobicity and recovery of hydrophobicity and chemical stability. But, the leakge current occurs on surface of the composite polymeric insulation materials when the insulator is used for a long time with severe contaminative condition and it can lead the contamination flashover. So the leakage current is important to estimate the condition of the silicone rubber surface. In this paper, aging characteristics of silicone rubber used for outdoor insulation have been hydrophobicity of silicone rubber in salt fog chamber with average leakage current monitoring for observing the transformation of surface degradation properties of silicone rubber with different ATH(alumina trihydrate, A1
$_2$ O$_3$ $.$ 3H$_2$ O) filler contents. The experimental results show that a higher peak leakage current and to raise a long time for tracking with increasing amount of ATH by the salt fog and heat recycle ageing. -
Two-layer self bonding insulating tape consists of butyl rubber(IIR ; Isobutylene-isoprene rubber) adhesive layer and polyethylene protective film. Butyl rubber have inherent characteristics such as resistance to corrosion and water, low temperature flexibility, excellent electrical insulating properties also resistance to environmental effect such as ozone and ultraviolet. Polyethylene film was used for the purpose of good insulating properties and resistance to ozone and ultraviolet. The tape was manufactured using extrusion and calender method.
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The Polypropylene films which are made by refinement of its pellet and formed as crystals are exposed to Radiation. As the results, degradation effects were observed in non-crystalline regions. It is thus considered that the effects occur by destroying of lattice binding force by Radiation. The distribution of degradation was increased with irradiation quantities of Radiation and dielectric constant of Polypropylene sheets irradiated Radiation was rapidly increased from above 10 MHz.
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Space charge distributions in silane crosslinked polyethylene (SXLPE)/ crosslinked polyethylene (XLPE) laminates was investigated using a pulsed electroacoustic (PEA) method. XLPE shows heterocharge while SXLPE shows homocharge. Positive charge is accumulated at the interface of SXLPE/XLPE laminate when applied electric field is more than 20 kV/mm. The charge profile at various temperatures was also acquired using temperature-controllable PEA system. Although applied electric field is only 8.6 kV/mm, positive interfacial charge starts to appear near 50
$^{\circ}C$ . -
For the c-axis oriented epitaxial YBa
$_2$ Cu$_3$ O$_{7-{\delta}}$ thin film on r-cut sapphire substrate it is necessary to deposit buffer layers. The CeO$_2$ buffer layer was deposited on sapphire substrate using RF magnetron sputtering system. We investigated XRD pattern of CeO$_2$ thin films at various sputtering conditions such as sputtering gas ratio, sputtering power, target to substrate distance, sputtering pressure and substrate temperature. The optimum condition was 15 mTorr with deposition pressure, 1:1.2 with$O_2$ and Ar ratio and 9cm with target to substrate distance. The CeO$_2$ (200) peak was notable for a deposition temperature above 75$0^{\circ}C$ . The YBa$_2$ Cu$_3$ O$_{7-{\delta}}$ was deposited on CeO$_2$ buffered r-cut sapphire substrate using pulsed laser ablation. The YBa$_2$ Cu$_3$ O$_{7-{\delta}}$ CeO$_2$ (200)/A1$_2$ O$_3$ thin film was exhibited a critical temperature of 89K.xhibited a critical temperature of 89K. -
The microstructure and the magnetic properties of Mn-Zn ferrite, which were power loss and saturation magnetic flux density, were investigated as the function of the process before firing. The highest initial permeability and the lowest power loss were attained to the specimen with CaO 400 ppm as a resulted from the highest solubility to SiO
$_2$ and the creation of liquid phase which improved sintering. The biggest grain size, the highest saturation magnetic flux density and the lowest power loss, which was resulted from that the eddy current loss increased as grain size increased but the hysteresis loss much more decreased and the hysteresis loss strongly influenced on the total power loss rather than the eddy current loss, were obtained to the Mn-Zn ferrite added 2wt% PVA. The power loss was lowest and the saturation magnetic flux density was highest in case of 1 ton/$\textrm{cm}^2$ and the grain size was not influenced. -
Lanthanide orthochromite materials have been widely studied as refractory conducting ceramics because of their electrical conductivity, oxidation resistance and high melting points. In this paper theoretical and experimental analysis about electric conductivity of the SHS prepared ceramics was carried out. The usefulness of the Seebeck-coefficient measurements as a function of P(O
$_2$ ) is emphasized. Electronic conduction was found to be n-type in the lower P(O$_2$ ) range, and p-type in the higher P(O$_2$ ) range. The carrier concentrations were calculated as a function of P(O$_2$ ) and defect structure. -
From 1994 the cooperation between NEU of China and MJU of South Korea for study of ReBaCuO (Re=Rare earth elements) superconductors has been carried out. The progress has been got in following projects. Critical current density (
$J_c$ ) of YBaCuO superconductor prepared by Melting Textured Growth (MTG) was improved. In the preparation of textured YBaCuO, 20 wt.% of YBaCuO 211 phase was added, which would be climactic for the microcracks in the textured YBaCuO. The effects of the 211 phase and Ag content on the superconductivity were studied and discussed in detail. The improved$J_c$ value was reached to 8$\times$ 10^4 A/cm^2 (77K,0T). Single phase$YbBa_{2}Cu_{3}O_{x}$ superconductor was sintered by the traditional powder metallurgical method, and its reaction process was studied. In recent years, NdBaCuO superconductor is being performed. The behavior of$Nd_{4}Ba_{2}Cu_{2}O_{10}$ (Nd422 phase) and the solid solubility, x in the superconductor$Nd_{1+x}Ba_{2-x}Cu_{3}O_{y}$ by the heat treatment in the low oxygen partial pressure (1%) or Ar at$950{\circ}C$ were investigated. The zone-melting process was used to make oriented NdBaCuO superconductor in order to increase the critical current density. -
Effects of addition of manganese and final reduction on segregation behavior of sulfur and final mangetic induction during final annealing have been investigated in the 300 ppm sulfur-contained 3% silicon-iron alloy strips with or without manganese. At the same concentration of sulfur, lower final reduction is favorable for final Goss texture. This is because the probability that the initial Goss grains survive under the highly segregated sulfur atmosphere and grow selectively within the segregated sulfur-free time range becomes higher. In the case of 3% silicon-iron with manganese, much lower magnetic induction was obtained, although the weak final reduction of 30% is given to the alloy, comparative to the 40%. This is because MnS particles acted as an reducer in the primary grain size.
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The link for the Superconducting Flux Flow Transistor (SFFT) which is based on the flux flow has been fabricated by the ICP etching methods. The channel width and the thickness of the SFFT were a 3
${\mu}$ m and about 300 nm, respectively. The superconducting characteristic of the link was measured by the x-ray diffraction and the E.D.S.. The SFFT etched by ICP showed an I-V characteristic like the three terminal transistor. -
We studied the electrical properties of Copper(II)-phthalocyanine (Cu-Pc) as a hole transport layer in organic light emitting devices (OLEDs). OLEDs were constructed with ITO/CU-Pc/triphenyl-diamine (TPD)/tris-(8-hydroxyquinoline) aluminum ( Alq
$_3$ ) + 4- (Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)/Al. It was consisted of a thin DCM in Alq$_3$ emission layer. We observed that the change of recombination zone was moved toward the cathode as the hole mobility increased due to the heat-treatment temperature of Cu-Pc layer increased. -
GaN nanowires has much interest as one-dimensional materials for blue light LED. GaN-based materials have been the subject of intensive research for blue light emission and high temperature/high power electronic devices. In this letter, the synthesis of GaN nanowires by the reaction of mixture of GaN nanowires by the reaction of mixture of Ga meta and GaN powder with NH
$_3$ using thermal chemical vapor deposition is reported. X-ray diffraction, energy dispersive x-ray spectrometer, scanning electron microscopy, and transmission electron microscopy indicate that those GaN nanowires with hexagonal wurtzite structure were about 60nm in diameter and up to several hundreds of micrometers in length. -
Carbon nanotubes(CNTs) was successfully grown on Ni coated silicon wafer substrate by applying PECVD technique(Plasma Enhanced Chemical Vapor Deposition). As a catalyst, Ni thin film of thickness ranging from 15∼30nm was prepared by electron beam evaporator method. In order to find the optimum growth condition, the type of the gas mixture such as C
$_2$ H$_2$ -NH$_3$ was systematically investigated by adjusting the gas mixing ratio in temperature of 600$^{\circ}C$ under the pressure of 0.4 torr. The diameter of the grown CNTs was 40∼150nm. As NH$_3$ etching time increased the diameters of the nanotubes decreased whereas the density of nanotubes increased. TEM images clearly demonstrated synthesized nanotubes was multiwalled. We investigated electrical properties for the application of FED. -
We fabricated Red Organic light-emitting devices(OLED). The Basic Device Structure is ITO/hole transfer layer, TPD(50nm)/red emitting layer, Alq3 doped with DCM2 or DCM2:rubrene(xnm)/electorn transfer layer, Alq3(50-xnm)/LiF(0.8nm)/Al(8nm) . The thickness of emitting layer(xnm) changed 5, 10, 20nm. we demonstrate red emitting OLED with dependent on the thickness and concentrators of Alq3 layer doped with DCM2 or co-doped with DCM2:ruberene. The Emission color and Brightness are changed with doping or co-doping condition, dopant concentarton. In the case of rubrene:DCM2 co-doped layer structure, the red color Purity and device efficiency is improved. The CIE index of rubrene co-doped OLED is x=0.67, y=0.31. By co-doping the Alq3 layer with DCM2, rubrene, EL efficiency improved from 0.38cd/A to 0.44cd/A in comparison whit DCM2 doped Alq3 layer.
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In this study, We have investigated degradation effects of blue organic electroluminescence devices that was consisted of TPD(N,N'-dyphenyl-N-N\`-bis(3-methyphenyl) as hole transport layer and Butyl-PBD (2- (4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole)-as emission layer and electron transport layer. We have studied characteristics of brightness and current density about blue OEL that was degradated layer. Two kinds of samples that were fabricated each continuous and non-continuous method was used.
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We report the characteristics of organic light emitting diodes (OLEDS) by controlling the carrier mobility according to the crystalline of Iron(II) Phthalocyanine(Fe-Pc) and metal-free Phthalocyanine (H
$_2$ -Pc). In order to change the recombination zone, we controlled the hole mobility by changing the crystal structures of Fe-Pc and H$_2$ -Pc. OLEDs were constructed with ITO/Fe-Pc/triphenyl-diamine (TPD)/tris-(8-hydroxyquinoline)aluminum (Alq$_3$ )/Al and ITO/H$_2$ -Pc/triphenyl-diamine (TPD)/tris-(8-hydroxyquinoline)aluminum (Alq$_3$ )/Al. The electroluminescent properties were changed according to the heat-treatments of Fe-Pc and H$_2$ -Pc. We observed that the recombination zone and the carrier mobility were changed as the higher occupied molecular orbital levels of Fe-Pc and H$_2$ -Pc decreased. -
We investigated the aligning capabilities for nematic liquid crystal (NLC) using a in-situ photodimerization method on various photopolymer surfaces. High Pretilt angle of the NLC can be measured by obliquely polarized UV exposure of 30
$^{\circ}$ on a photo-crosslinkable polyimide (PI) based polymer surface for 3 min. The pretilt angle of the NLC generated on the photopolymer surface using the in-situ photodimerization method was higher than that of a blending photopolymers (PI and cinnamate materials). -
The structure characteristics of varistor of Zn oxide to depend on the breakdown voltage has been investigated to annealing condition by additive material of Sb
$_2$ O$_3$ system. The breakdown voltage that has not doping Sb$_2$ O$_3$ was 235[V]. ZnO varistors was shown ohmic properties when it's applied voltage was below critical voltage. It was shown non-ohmic properties over critical voltage, because current was increased with decreasing resistance. High voltage ZnO varistors had high breakdown voltage, but it had bad electrical stability with various surge. Sb$_2$ O$_3$ was increased non-linear coefficient in ZnO varistors grain boundary. -
In this study, the piezoelectric and dielectric properties and Temperature stability of resonant frequency with MnO
$_2$ doped 0.36Pb(Sc$_{1}$ 2/Nb$_{1}$ 2/)O$_3$ - 0.25Pb(Ni$_{1}$ 3/Nb$_{2}$ 3/)O$_3$ -0.39PbTiO$_3$ (hereafter PSNNT) were investigated. The tetagonality of crystal structure was developed with increasing MnO$_2$ additive content. With increasing MnO$_2$ additive content, the electromechanical coupling factor and quality factor were increased. Electromechanical coupling k$_{p}$ and quality factor Q$_{m}$ at MnO$_2$ doped with 2.0mol% were showed highest value of 55.6% and 252. In the case of specimen for MnO$_2$ doped with 2mol%, temperature dependance of resonant frequency had a good properties.ies. -
The effects of the sintering additives such as Bi
$_2$ O$_3$ and V$_2$ O$_{5}$ on the microwave dielectric and sintering properties of ZnTiO$_3$ system were investigated. Densities of >97% of the theoretical densities have been attained for ZnTiO$_3$ at the sintering temperature range of 870~90$0^{\circ}C$ with Bi$_2$ O$_3$ and V$_2$ O$_{5}$ additions of$_3$were obtained with 0.6wt% Bi $_2$ O$_3$ and 0.5wt% V$_2$ O$_{5}$ ; Qxf$_{o}$ = 48,400 GHz,$\varepsilon$ $_{r}$ = 22, and$\tau$ $_{f}$ = -43 PPm/$^{\circ}C$ . In order to improve temperature coefficient of resonance frequency, TiO$_2$ was added to the above system. The optimum amount of TiO$_2$ was 15mo1% when sintered at 87$0^{\circ}C$ , at which we could obtain following results ; Qxf$_{o}$ = 44,700 GHz,$\varepsilon$ $_{r}$ = 26, and$\tau$ $_{f}$ = 0 ppm/$^{\circ}C$ .EX>.>.EX>.>.>.EX>. -
In this paper, internal antennas for IMT-2000 handset(1.92∼2.17 GHz) were designed to be capable of being mounted on the circuit-board with a CPW(coplanar waveguide) feeding structure. The chip antennas were miniaturized to a greater extent by fabricating multilayer high dielectric ceramic(
$\varepsilon$ $\sub$ r/=7.8) hexahedron. The proposed antennas has λ/4 monopole element with helical structure in the multilayer dielectric ceramic hexahedron. The simulated and measured results were invesgated with width, length, and thickness of helical structure in the hexahedron. -
The effect of Cr
$_2$ O$_3$ (0 to 0.5 wt%) doping on the microstructure and electrical properties of ternary Pb(Zr,Ti)O$_3$ -Pb(Ni,Nb)O$_3$ piezoelectric ceramic has been investigated. Abnormal grain growth (grain size 3.3 to 11.2$\mu$ m) and densification are found. Minor additives of$\leq$ 0.1 wt% improve the mechanical coupling factor, but with more additives of$\geq$ 0.2 wt% electrical properties deteriorate. Thus, these phenomna can be ascribed mainly to anomalous developed microstructure. The large grains were composed of a core region that is free of Cr and a surrounding shell region rich in Cr. The interfaces between the core and the shell were composed of misfit dislocations. The mechanical properties of the specimens were strongly influenced by this microstructural change. The microstrutural and compositonal evolution of the specimens containing different amounts of Cr$_2$ O$_3$ were monitored. Electrical properties were measured and related to the variations in the microstructure. -
In this study, P
$b_{0.88}$ (L$a_{a}$ N$d_{l-a}$ )$_{0.08}$ (M$n_{1}$ 3/S$b_{2}$ 3/)$_{0.02}$ $Ti_{0.98}$ $O_3$ system ceramics were manufactured for 20 MHz class resonator application. Electromechanical coupling factor, mechanical quality factor and dynamic range of 3rd overtone thickness vibration mode were measured as the variations of La and Nd molar ratio. Mechanical quality factor and dynamic range at$\alpha$ =0.6 composition ceramics showed the highest value of 2, 691 and 52.37 dB, respectively. The tempearture coefficient of resonant frequency measured from -2$0^{\circ}C$ to 8$0^{\circ}C$ showed an excellent value of 5ppm/$^{\circ}C$ at$\alpha$ = 1 composition ceramics. ceramics.s. -
The piezoelectric properties of 0.05pb(A
$l_{0.5}$ N$b_{0.5}$ )$O_3$ -0.95Pb(Z$r_{0.52}$ $Ti_{0.48}$ )$O_3$ +0.7wt%N$b_2$ $O_{5}$ +0.5wt%Mn$O_2$ ceramics with the additives of BaC$O_3$ were investigated. For the additions of BaC$O_3$ , the dielectric constant ($\varepsilon$ $^{T}$ $_{33}$ ), the piezoelectric constant ($d_{33}$ ), the electromechanical coupling factor ($k_{p}$ ), and . the mechanical quality factor ($Q_{m}$ ) were increased, but dielectric loss (tan$\delta$ ) was decreased. The highest piezoelectric properties and dielectric properties were observed at the sintered temperature of 120$0^{\circ}C$ and 0.4 wt% of BaC$O_3$ , and the properties of$d_{33}$ ,$k_{p}$ , and$Q_{m}$ were 339(x10$^{-12}$ C/N), 59% and 1754, respectively.vely.y.y. -
A piezo-buzzer being used for the purpose of generation of audible frequency, which is a electric-acoustic transducer utilizing the inverse piezoelectric effect. Also it can be used for a pressure sensor according to the piezoelectric effect. But the output of a piezo-buzzer is a differential signal. In this study, we've made a system that can measure a real pressure by integration of output signal. According to our results, it could be found a possibility of application for pressure sensor by measurement of output characteristics when a piezo-buzzer was pressurized and depressurized, and by measuring of an error by means of the drift current of OP-Amp, etc..
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(Ba
$\sub$ 0.6-x/Sr$\sub$ 0.4/Ca$\sub$ x/)TiO$_3$ (x=0.10, 0.15, 0.20) specimens were fabricated by the solid state reaction method and then the structural and dielectric properties as a function of the composition ratio and sintering temperature were studied. The BSCT(50/40/10) specimen sintered at 1500$^{\circ}C$ showed the highest average grain size(18.25${\mu}$ m). The Curie temperature and dielectric constant at room temperature decreased with increasing Ca content. The dielectric constant and dielectric loss of the BSCT(50/40/10) specimen, sintered at 1450$^{\circ}C$ , were about 4324 and 0.972% at 1KHz, respectively. Dielectric constant at room temperature decreased with increasing an applied field, tunability of the BSCT(50/40/10) sintered at 1300$^{\circ}C$ was 18%. -
In the composition of 0.16BaO-0.15(Nd
$\_$ 0.87/,Bi$\_$ 0.13/)$_2$ O$_3$ -0.69TiO$_2$ $.$ Glass [EG-2782] 3wt% addition sintered at 1080$^{\circ}C$ , we could obtained microwave properties of dielectric constant$\varepsilon$ $\_$ r/= 80.1, quality factor Q${\times}$ f = 810 (at 3.5 GHz]) and temperature coefficient of resonant frequency$\tau$ $\_$ f/ = -1.3 [ppm/$^{\circ}C$ ] -
Pb(Zr
$\sub$ 0.52/Ti$\sub$ 0.48/)O$_3$ (PZT) thin films have been prepared by rf-magnetron sputtering methods and investigated the structural and electrical properties. In order to investigate the effects of sputtering conditions, input power was controlled during deposition. Crystallization process and microstructure of PZT thin films were largely affected by input power. Highly crystallized PZT films with the perovskite structure were successfully obtained on Pt/Ti bottom electrode. The dielectric constants and polarization of PZT thin films were increased with increasing input power, and the coercive electric field was decreased with increasing input power . The dielectric constant of PZT thin films with input power 150 W was 966 at 1 kHz. we, authors, proposed that preferred orientation of PZT thin films were controlled by input power in sputtering methods. -
The (Sr
$_{l-x}$ Ca$_{x}$ )TiO$_3$ (SCT) thin films are deposited on Pt-coated electrode(Pt/TiN/SiO$_2$ /Si) using RF sputtering method with substitutional contents of Ca. The maximum grain of thin films is obtained by substitution of Ca at 15[mol%]. The dielectric constant was increased -with increasing the substitutional contents of Ca, while it was decreased if the substitutional contents of Ca exceeded over 15[mol%]. The dielectric constant changes almost linearly in temperature ranges of -80~+90[$^{\circ}C$ ]. The temperature properties of the dielectric loss have a stable value within 0.02 independent of the substitutional contents of Ca. The current-voltage characteristics of SCT15 thin films showed the increasing leakage current as the measuring temperature increases.ses. -
The application of the ultrasonic nozzle has been extended because it is possible atomization of liquid material. In this study, the driving characteristics of the ultrasonic nozzle on the driving circuit were investigated. And the characteristics of the ceramic oscillator were investigated for the temperature stability. The ceramic oscillator were made the Pb[(Sb
$\sub$ 1/2/,Nb$\sub$ 1/2/)$\sub$ 0.035/-(Mn$\sub$ 1/3/Nb$\sub$ 2/3/)$\sub$ 0.065/- (Zr$\sub$ x/Ti$\sub$ l-x/)$\sub$ 0.9/]O$_3$ with mole ratio of Zr/Ti. The ceramis oscillator were need the curie temperature of the over 300[$^{\circ}C$ ] for the temperature stability. When the Zr/Ti ratio was 49/51, it's curie temperature is 322[$^{\circ}C$ ] and the electromechanical coupling factor(k$\sub$ p/) and mechanical quality factor(Q$\sub$ m/) showed the values of 0.555, 1,214, respectively The resonance frequency of ceramic oscillator were from 40KHz to 45KHz. So that, the driving circuit were made a possibility that the frequency are variable. The driving current of ultrasonic nozzle showed the value of maximum 80[mA]. Also, The surface temperature of ceramic oscillator showed 80[$^{\circ}C$ ] at driving time 10[min]. We knew that the ultrasonic nozzle had stabile driving above 10[min.]. -
Zinc oxide(ZnO) films were prepared by ultrasonic spray pyrolysis on indium (In) films deposited by evaporation and subsequently submitted to rapid thermal annealing (RTA). The RTA was processed in air or a vacuum ambient. The crystallographic properties and surface morphologies of the films were characterized before and after the RTA by X-ray diffraction (XRD) and scanning electron microscopy(SEM), respectively. The resistivity variation of the films with RTA temperature and time was measured by the 4-point probe method. Auger electron spectroscopy(AES) was carried out to figure out the distribution of indium atoms in the ZnO films. The resistivity of the ZnO on In(ZnO/In) films decreased to 2
${\times}$ 10$\^$ -3/$\Omega$ cm by diffusion of the In. The In diffusion into the ZnO films roughened the surface of the ZnO films. The results of depth profile by AES showed a hump of In atoms around ZnO/In interface after the RTA at 800$^{\circ}C$ , which disappeared by the RTA at 1000$^{\circ}C$ . The effects of temperature, time and ambient during the RTA on the structural and electrical properties of the ZnO/In films were discussed. -
In recent years, The tantalum nitride(TaN) thin-film has been developed for the electronic resistor and capacitor. In this papers, The effect of thermal annealing in the temperature range of 300∼700
$^{\circ}C$ on the sheet resistor properties and microistructure of tantalum nitride(TaN) thin-film deposited by RF sputtering was studied. XRD(X-ray diffractometer) and AFM were used to observe electrical properties and microstructrue of the TaN film and sheet resistance. The TCR properties of the TaN films were discussed in terms of annealing temperature, ratio of nitrogen, crystallization and thin films surface morphology due to annealing temperature. The leakage current of the TaN thin film annealed 400$^{\circ}C$ was stabilized in the study. How its was found that the sheet resistance in the polycrystalline TaN thin film decreased with increasing the annealing temperature above 600$^{\circ}C$ after sudden peak upen 400$^{\circ}C$ . -
1018-1021 The CuO-P
$_2$ O$_{5}$ containing P$_2$ O$_{5}$ as glass-former were prepared by press-quenching method on the copper plate. By post-heat treatment of these glasses, the CuO-P$_2$ O$_{5}$ -V$_2$ O$_{5}$ -g1ass ceramics was obtained and the crystallization behavior and dc conductivities were investigovted. The heat-treated glass-ceramics decreased in electrical conductivity by the order of 10$^1$ compared to amorphous glass. The linear relationship between In($\sigma$ T) and T$^{-1}$ indicated that electrical conduction in CuO-P$_2$ O$_{5}$ -V$_2$ O$_{5}$ -gass occurred by a small polaron hopping. -
This paper presents the characteristics of TaN thin-film as high-temperature strain gauges, which were deposited on Si substrate by DC reactive magnetron sputtering in an argon-nitrogen atmosphere(Ar-(4∼20%)N
$_2$ ). The electrical and mechanical characteristics of these films investigated with the thickness range 1650∼1870${\AA}$ and room temperature resistivities in the range 178.3${\mu}$ $\Omega$ cm to 3175.7${\mu}$ $\Omega$ cm. The TaN thin-film strain gauge deposited in Ar-(20%)N$_2$ atmosphere is obtained a temperature coefficient of resistance(TCR), 0∼-1357 ppm/$^{\circ}C$ in the temperature range 25∼275$^{\circ}C$ and a high temporal stability with a longitudinal gauge factor, 2.92∼3.47. Because of their high resistivity, low TCR and linear gauge factor, these cermet thin-film may allow high-temperature strain gauges miniaturization. -
Zinc films have been deposited onto various buffer layers, Al, Al-Cu, Ag and Ag-Al, by vacuum evaporation method in order to investigate the film microstructure and its consequence on the film growth. Zn films were grown onto Al buffer layers with faster rates than on Ag buffer layers, because of the presence of preferred growth orientation. Especially, in the Zn film formation on the Ag layers, intermetallic compounds AgZn was formed to cause the different growth orientation from Zn film obtained on the Al layers.
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Strontium barium niobate, (Sr
$\sub$ 0.5/Ba$\sub$ 0.5/Nb$_2$ O$\sub$ 6/), thin films of various composition were prepared by the sol-gel method. Solution derived from acetate powders and niobium ethoxide in a mixture of acetic acid, ethylene glycol and 2-methoxyehanol was spin-coated onto bare silicon, Pt-coated silicon and fused silica substrates. Processing parameters were optimized to develop stable solutions which yielded films with relatively low crystallization temperatures. It was determined that ethylene glycol was a necessary component of the solution to increase stability against precipitation and to decrease the crystallization temperature of the films as confirmed by XRD and FT-IR analyses. -
The sapphire orientation dependence of the crystallization of ZnO thin films has been studied using real-time synchrotron x-ray scattering. The amorphous ZnO thin films with a 2400-
${\AA}$ -thick were grown on sapphire(110) and sapphire(001) substrates by radio frequency magnetron sputtering at room temperature. The amorphous ZnO films were crystallization into epitaxial ZnO(002) grains both on the sapphire(110) and on the sapphire(001) substrates. The epitaxial quality, such as mosaic distribution and crystal domain size, of the ZnO grains on the sapphire(110) is high, similar to that of the ZnO grains on the sapphire(001). With increasing the annealing temperature to 600$^{\circ}C$ , the mosaic distribution and the crystal domain size of ZnO(002) grains in the film normal direction was improved and decreased, respectively. -
A method for designing antireflection (AR) and antistatic (AS) films by the use of conducting polymer as an electrically conductive transparent layer is proposed. The conducting AR film is composed of four-layer with alternating high and low refractive index layer: silicon dioxide (n=1.44) and titanium dioxide (n=2.02) prepared at low temperature by sol-gel method are used as the low and high refractive index layer, respectively. The 3,4-polyethylenedioxythiophene (PEDOT) which has the sheet resistance of 10
$^4$ $\Omega$ /$\square$ is used as a conductive layer. Optical constant of ARAS film was measured by the spectroscopic ellipsometer and from the measured optical constants the spectral properties such as reflectance and transmittance were simulated in the visible region. The reflectance of ARAS films on glass substrate was below 0.8 %R and the transmittance was higher than 95 % in the visible wavelength (400-700 nm). The measured AR spectral properties was very similar to its simulated results. -
In this study, characteristics of LPB having gold anode fabricated by sputtering methode were analyzed. As results, The 1st efficiency and the impedance characteristics of LPB decreased with increased gold coated on anode and current collector. But the rate characteristics and charge-discharge cycling characteristics increased with increased gold coated on anode and current collector. During 2C discharge of the rate characteristics test, the rate characteristics of LPB without gold coated and the rate characteristics of LPB with gold coated in twice were 159mAh/g and 189mAh/g, respectively. The discharge capacity was gradually degreased with the discharge cycling to about 20th cycles. But LPB with gold coated in twice was stabilized than LPB without gold coated.
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The displacemant current measuring system used for detecting the dynamic behavior of monolayers at the air-water interface is described. It basically consists of a film balance, a pair of electrodes connected to each other through a sensitive ammeter. Here, one electrode is suspended in air and the other electrode is placed in the water. With Maxwell-displacement-current-measuring method, the phase transitions of Poly-
${\gamma}$ -benzyl D-glutamate(PBDG) on a water surface were detected. Measured surface pressure, displacement current and dipole moment of monolayers of PBDG on the water surface. We measured analyzed displacement current that occur when differed temperature. Could know that displacement current is proportional in increase of temperature and great as experiment result. -
There is great interest in developing magnetoresistance(MR) sensor, using ferromagnetic, electrically non-magnetic conducting and antiferromagnetic films, especially for the use in weak magnetic fields. Here, we report single and Wheatstone-bridge type of MR sensors made in Si(001)/HiO(300
$\AA$ )/NiFe bilayers. Angular dependence of MR profiles was measured in Si(001)/NiO(300$\AA$ )/NiFe(450$\AA$ ) films as a function of an angle between current and applied field direction, also, linearity was determined. AMR characteristics of single MR sensors was well explained with single domain model. Good linearity in 45$^{\circ}$ Wheatstone-bridge type of MR sensors consisting of 4 single MR sensors made in Si(001)/NiO(300$\AA$ )/NiFe(450$\AA$ ) was shown in the range of about$\pm$ 50 Oe. -
This paper deals with underground transmission system of present and ZnO element of newly developed. in the characteristics of ZnO element of newly developed, an newly developed ZnO element compared with previous ZnO element that electrical characteristics and external characteristics. In result, characteristics of newly developed ZnO element is improved than previous one.
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By comparison of the experimental results in two systems of ZnO varistors, its appear that Sb
$_2$ O$_3$ is the indispensable element for twinning in ZnO varistors, and the Zn$_{7}$ Sb$_2$ O$_{12}$ spinel acts as the nucleus to form twins. A1$_2$ O$_3$ is not the origin of twinning in ZnO varistor, but it was found that A1$_2$ O$_3$ could strengthen the twinning and form a deformation twinning by ZnA$_{12}$ O$_4$ -dragging and pinning effect. The inhibition ratios of grain growth and nonuniformity of two systems ZnO varistors increase with the increase of A1$_2$ O$_3$ content. The twins affect the inhibition of grain growth, the mechanism could be explained follow as : twins increase the mobility viscosity of ZnO grain and grain boundary, and drag ZnO grain and liquid grain boundary during the sintering, then the grain growth is inhibited, and the microstructure becomes more uniform.orm.m. -
Deep Interests have been paid on the application of non-thermal plasma technique to solve the environmental pollution problems.
$CO_2$ , is one of the severe pollutants which cause the acid rain and global warming. In this study, in order to improve the conversion efficiency of$CO_2$ , the streamer corona discharge plasma and barrier discharge plasma reactors were made, and the conversion characteristics of$CO_2$ by the corona discharge plasma and some discharge characteristics of these discharge chambers are studied experimentally. -
Effects of compacting pressure on the electrical and sintering characteristics of Cu25Cr contact material have been investigated. Cu25Cr contact materials were prepared by solid and liquid-phase sintering methods varying compacting pressure. Influence of compacting pressure on electrical characteristics were investigated in the cylindrical stainless-steel vessel using L-C resonant circuit. The physical and electrical properties of solid-phase sintered Cu25Cr material were found to be improved by increased compacting pressure. On the other hand, it was found that compacting pressure had little influence in case of liquid-phase sintered Cu25Cr material. After conditioning, contact resistance of Cu25Cr material was decreased regardless of compacting pressure. With increased compacting pressure, interrupting ability was shown to be increased.
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We described a method resonant mode identification in dielectric-rod loaded cylindrical cavity resonators. Resonant frequency of dielectric loaded cavity is calculated by analyzing the characteristic equation. The characteristic equation is solved by using the ContourPlot graph of Mathematica. As the result of comparing calculation value and experimental value of resonant frequencies, we know that the field representation of non-decaying mode is exact. The contour graph method is not a method using approximated representation of electromagnetic field variation at the outer area of dielectric in the resonators but a method using exact representation.
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The nitrogen oxides, NO and NO2, abbreviated usually as NOx, emitted from combustion facilities such as power plants and automobiles are the typical air-pollutants causing acid rain and photochemical smog. In order to solve the NOx-related pollution problems effectively, we need efficient techniques to monitor NOx in the combustion exhausts and in environments. Development of solid-state electrochemical devices for detecting NOx is demonstrated based on various combination of solid electrolytes and auxiliary sensing materials. The object of this research is to develop various sensor performance for solid state amperometric sensor, and to test gas sensor performance manufactured. So we try to present a guidance for developing amperometric gas sensor. We concentrated on development of manufacturing process and performance test.
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An anolmalous magnetoresistance effect has been theoretically studied at very low temperatures for composite normal metal conductors. This anomalous behavior is due to transverse Hall currents in the composite which would result in increased losses and higher effective resistance for the composite conductor. In this paper, transverse current flow and effective resistance with Cu-Al conductor configuration were analyzed using FEM(finite element method) for predicting the Hall losses to be resulted in anomalous magnetoresistance effect. And they are plotted three dimensionally to be visualized.
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Ultrafine NiO/YSZ composite powders were prepared by using a glycine nitrate process for anode material of solid oxide fuel cells. The specific surface areas of synthesized NiO/YSZ composite powders were examined with controlling pH of a precursor solution and the content of glycine. The characteristics of synthesized composite powders were examined with X-ray diffractometer, a BET method with N
$_2$ absorption, scanning and transmission electron microscopy. The strongly acid precursor solution increased the specific surface area of the synthesized composite powders. This is suggested to be caused by the increased binding of metal ions and glycine under a strong acid solution of pH=0.5 that lets glycine consist of mainly the amine group of NH$_3$ $\^$ +/. After sintering and reducing treatment of NiO/YSZ composite powders synthesized by GNP, the Ni/YSZ pellet showed ideal micro-structure very fine Ni parties of 3-5${\mu}$ m were distributed uniformly and fine pores around Ni metal particles were formed, thes, leading to an increase of the triple phase boundary among gas Ni and YSZ. -
The (Sr
$\sub$ 0.85/Ca$\sub$ 0.15/)TiO$_3$ (SCT) thin films are deposited on Pt-coated electrode(Pt/TiN/SiO$_2$ /Si) using RF sputtering method. The crystallinity of SCT thin films is increased with increase of substrate temperature in the temperature range of 100[$^{\circ}C$ ]∼500[$^{\circ}C$ ]. Also, the crystallinity of SCT thin films are obtained at the substrate temperature above 400[$^{\circ}C$ ]. SCT thin films had (111) preferred orientation. The dielectric constant changes almost linearly in temperature ranges of-80∼+90[$^{\circ}C$ ]. The temperature properties of the dielectric loss have a stable value within 0.1. SCT thin films used in this study show the phenomena of dielectric relaxation with the increase of frequency, and the relaxation frequency is observed above 200[kHz]. -
Temperature-dependent current-voltage characteristics of Organic Light-Emitting Diodes(OLEDs) were studied. The OLEDs were based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1, 1'-diphenyl-4, 4'-diamine (TPD) as a hole transport and trim(8-hydroxyquinoline) alulninum(Alq
$_3$ ) as an electron transport and emissive material. The current-voltage characteristics were measured in the temperature range of 10[K] and 300[K]. A conduction mechanism in OLEDs was interpreted in terms of tunneling and trap-filled limited current. -
Steady state thermal analysis has been done by a finite element method in a diode of 12kV blocking voltage. The diode was fabricated by soldering ten pieces of 1200V diodes in series, capping a dummy wafer at the far end of diode series, and finally wire bonded for building anode and cathode terminal. In order to achieve high voltage and reliability, the edge of each diode was beveled and passivated by resin with a thickness of 25
${\mu}$ m. It was assumed that the generated heat which is mainly by the on-state voltage drop, 9V for 12kV diode, is dissipated by way of the conduction through diodes layers to bonding wire and of the convection at the surface of passivating resin. It was predicted by the thermal analysis that the temperature rise of a pn junction of the 12kV diode can reach at the range of 16∼34$^{\circ}C$ under the given boundary conditions. The thickness and thermal conductivity(0.3∼3W/m-K) of the passivating resin did little effect to lower thermal resistance of the diode. As the length of the bonding wire increased, which means the distance of heat conduction path became longer, the thermal resistance increased considerably. The thermal analysis results imply that the generated heat of the diode is dissipated mainly by the conduction through the route of diode-dummy wafer-bonding wire, which suggests to minimize the length of the wire for the lowest thermal resistance. -
The basic design structure of RC-GCTs (Reserve-Conducting Gate-Commutated Thyristors) is firstly given in this paper. The bulk of wafer is punch-through (PT) type with high resistivity and narrow N-base width. The photo-mask was designed upon the turn-off characteristics of GCT and solution of separation between GCT and diode part. The center part of Si wafer is free-wheeling diode (FWD) and outer is GCT part which has 240 fingers totally. The switching performance of GCT was investigated by Dessis of ISE. The basic manufacture process of 2500V-4500V RC-GCTs was given in this work. Additionally, the local carrier lifetime control by 5Mev proton irradiation was adopted so as to not only to have the softness of reverse recovering for FWD but for reduction of turn-off losses of GCT as well.
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(1) By comparing and analyzing the distribution of brightness as domestic lamps and Japanese products go thinner and lighter, we set an effective design standard. (2) By comparing and analyzing the feature, brightness, chromaticity and uniformity of domestic LGPs and Japanese products, early home-manufacturing and stabilization in home-manufacturing are possible. (3) By comparing and analyzing the distribution of brightness as sheets are varied, we can design an ideal sheet composition.
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Ferroelectric
$Bi_{4-x}$ La$_{x}$ Ti$_3$ O$_{12}$ (BLT)thin films with various compositions(x=0.65, 0.70, 0.75) were prepared on Pt//Ti/SiO$_2$ /Si(100) substrate by metal-organic deposition. The electrical and structural characteristics of BLT thin films were investigated to develop ferroelectric thin films for capacitor layers of FRAM. After spin coating, thin films were annealed at$650^{\circ}C$ for 1hour in oxygen atomosphere. Scanning electron micrographs showed uniform surfaces composed of rod-like grains. The$Bi_{4-x}$ La$_{x}$ Ti$_3$ O$_{12}$ (x=0.70) thin film capacitors with a Pt top electrode showed better ferroelectric properties than other films. At the applied voltage of 5V, the dielectric constant($\varepsilon$ $_{r}$ ), dissipation factor(tan$\delta$ ),remanent polarization(2Pr), and coercive field(2Ec) of the$Bi_{4-x}$ La$_{x}$ Ti$_3$ O$_{12}$ (x=0.70)thin films were about 272.54, 0.059, 32.4$\mu$ C/cm$^2$ , 2Ec=119.9kV/cm. Also the capacitor did not show any significant fatigue up to 4.8$\times$ 10$^{10}$ read/write switching cycles.hing cycles.s. -
요실리콘을 기반으로 하는 박막은 반도체 재료로 Si, Si:Ge, SiC등이 사용되고있으며, 절연박막재료로 SiN, SiOxNy, SiOx 등이 있다. 이들 재료는 국내 반도체 산업의 핵심위치에 있는 물질이다. 한국 산업의 근간이라 할 수 있는 메모리분야에 적용될 뿐만 아니라 TFT-LCD, 태양전지, 각종 센서, X-ray 사진 촬영기 개발에도 응용되고 있다. 본 논문에서는 Silicon-based 박막의 제조기법과 그에 따른 다양한 실리콘 박막 실리콘 트랜지스터를 이용한 능동형 액정과 유기발광 화소제어 활용, 센서 응용 부분에서 태양전지, X-ray 촬영기활용 분야에서 기술현황 시장분석을 통해 차세대 연구개발의 방향을 제시하고자 한다. 현재 국내에서 실리콘 박막의 가장 큰 응용 분야는 메모리 소자의 평판디스플레이의 TFT-LCD 시장이다. 그러나 실리콘 박막으로 가능한 응용분야는 아직 산업계에서 열매를 맺지 못한 분야가 더 많고 실제로 적용할 수 있는 분야의 다양함을 본 논문을 통해 소개한다.