Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference (한국전기전자재료학회:학술대회논문집)
The Korean Institute of Electrical and Electronic Material Engineers
- Annual
2001.11b
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In common globular proteins, the native form is in its most stable state. However, the native form of inhibitory serpins (serine protease inhibitors) and some viral membrane fusion proteins is in a metastable state. Metastability in these proteins is critical to their biological functions. Our previous studies revealed that unusual interactions, such as side-chain overpacking, buried polar groups, surface hydrophobic pockets, and internal cavities are the structural basis of the native metastability. To understand the mechanism by which these structural defects regulate protein functions, cavity-filling mutations of a 1-antitrypsin, a prototype serpin, were characterized. Increasing conformational stability is correlated with decreasing inhibitory activity. Moreover, the activity loss appears to correlate with the decrease in the rate of the conformational switch during complex formation with a target protease. We also increased the stability of a 1-antitrypsin greatly via combining various stabilizing single amino acid substitutions that were distributed throughout the molecule. The results showed that a substantial increase of stability, over 13 kcal/mol, affected the inhibitory activity with a correlation of 11% activity loss per kcal/mol. The results strongly suggest that the native metastability of proteins is indeed a structural design that regulates protein functions and that the native strain of a 1-antitrypsin distributed throughout the molecule regulates the inhibitory function in a concerted manner.
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Orthorhombic type
$LiCo_{x}Mn_{1-x}O_{2}$ (0${\times}$ 0.14) oxides have been synthesized by hydrothermal treatment of$(Co_{x}Mn_{1-x})_{3}O_{4}$ precursors and LiOH aqueous solution at$170^{\circ}C$ . As-synthesized powders showed well-ordered${\beta}-NaMnO_{2}$ structures, and the products were single crystalline particle oxides from TEM observations. The particle size decreased with increasing the amount of Co substituent. Much more improved capacity upon 100 cyclings was clearly seen in orthorhombic$LiCo_{0.1}Mn_{0.9}O_{2}$ , comparing to orthorhombic$LiMnO_2$ . -
반도체 동작시에 파워 손실을 최소화하는 것은 2000년대의 에너지, 산업전자, 정보통신 산업분야에서의 가장 주요한 요구 사항중의 하나이다. 실리콘계 반도체 소자들은 완전히 새로운 구동기구의 소자가 개발되지 않는 한, 실리콘 재료의 낮은 열전도율이나 낮은 절연파괴전계와 같은 물리적 특성한계 때문에 이러한 요구를 만족시키는 것이 불가능한 실정이다. 따라서 21세기를 위한 대안으로 고열전도융의 WBG(WideBand-Gap) 물질 그 중에서도 탄화규소(SiC) 반도체가 제시되고 있다. SiC 반도체는 실리콘에 비하여 밴드갭(band gap:
$E_{g}$ )이 높을 뿐만이 아니라 절연파괴강도 ($E_{B}$ )가 한 자릿수 이상 그리고 전자의 포화 drift 속도,$V_{s}$ 및 열전도도 k가 3배 가량 크다. 따라서 SiC는 고온 동작 내지는 고내압, 대전류, 저손실 반도체를 제작하는데 아주 유리하다. 본고에서는 응용성이 넓고, 단결정 제조가 비교적 용이한 SiC 반도체의 기술현황에 대하여 살펴보고자 한다. -
Nonvolatile semiconductor memory devices with reoxidized nitrided oxide(RONO) gate dielectrics were fabricated, and nitrogen distribution and bonding species which contribute to memory characteristics were analyzed. Also, memory characteristics of devices depending on the anneal temperatures were investigated. The devices were fabricated by retrograde twin well CMOS processes with
$0.35{\mu}m$ Nonvolatile semiconductor memory devices with reoxidized nitrided oxide(RONO) gate dielectric were fabricated, and nitrogen distribution and bonding species which contributing memory characteristics were analyzed. Also, memory characteristics of devices according to anneal temperatures were investigated. The devices were fabricated by$0.35{\mu}m$ retrograde twin well CMOS processes. The processes could be simple by in-situ process of nitridation anneal and reoxidation. The nitrogen distribution and bonding state of gate dielectric were investigated by Dynamic Secondary Ion Mass Spectrometry(D-SIMS), Time-of-Flight Secondary Ion Mass Spectrometry(ToF-SIMS), and X-ray Photoelectron Spectroscopy(XPS). Nitrogen concentrations are proportional to nitridation anneal temperatures and the more time was required to form the same reoxidized layer thickness. ToF-SIMS results show that SiON species are detected at the initial oxide interface and$Si_{2}NO$ species near the new$Si-SiO_{2}$ interface that formed after reoxidation. As the anneal temperatures increased, the device showed worse retention and degradation properties. These could be said that nitrogen concentration near initial interface is limited to a certain quantity, so excess nitrogen are redistributed near the$Si-SiO_{2}$ interface and contributed to electron trap generation. -
In this study, recovery of plasma etching· damage in PZT thin film with additive gas and re-annealing after etching have been investigated. The PZT thin films were etched as a function of
$Cl_2/CF_4$ with addition of Ar and$O_2$ with inductively induced plasma. The etch rates of PZT thin films were 1450$\AA$ /min at 30% additive Ar into$(Cl_2(80%)+CF_4 (20%))$ and 1100$\AA$ /min at 10% additive$O_2$ into$C(Cl_2(80%)+CF_4(20%))$ . In order to recovery properties of PZT thin films after etching, the etched PZT thin films were re-annealed at various temperatures in at$O_2$ atmosphere. From the hysteresis curves, ferroelectrical properties are improved by$O_2$ re-annealing process. The improvement of ferroelectric behavior at annealed sample is consistent with the increase of the (100) and (200) PZT peaks revealed by x-ray diffraction (XRD). From x-ray photoelectron spectroscopy (XPS) analysis, intensity of Pb-O, Zr-O and Ti-O peak are increased and the chemical residue peak is reduced by$O_2$ re-annealing. The ferroelectric behavior consistent with the dielectric nature of$Ti_xO_y$ is recovered by$O_2$ recombination during rapid thermal annealing process. -
$SrBi_2Ta_2O_{9}$ thin films were etched at high-density$Cl_2/CF_4/Ar$ in inductively coupled plasma system. The etching of SBT thin films in$Cl_2/CF_4/Ar$ were chemically assisted reactive ion etching. The maximum etch rate was 1300$\AA$ /min at 900W in$Cl_2(20)/CF_4(20)/Ar(80)$ . As rf power increase, radicals (F, Cl) and ion(Ar) increase. The influence of plasma induced damage during etching process was investigated in terms of the surface morphology and th phase of X-ray diffraction. The chemical residue was investigated with secondary ion mass sperometry. -
This thesis deal with ferroelectric and ferrimagnetic materials, PZT/Ferrite ceramics. We conducted test of magnetical and electrical measurement. From this measurement, We obtained tunability and we can control characteristic impedance(
$Z_0$ ) from permeability($\mu$ ) and dielectric constant($\varepsilon$ ) for impedance matching in transmission line. -
In this study, the capacitance-voltage properties of
$(Sr_{1-x}\cdot Ca_x)TiO_3(0.05{\leq}x{\leq}0.20)$ -based grain boundary layer ceramics were investigated. The ceramics were fabricated by the conventional mixed oxide method. The sintering temperature and time were$1480\sim1500^{\circ}C$ and 4 hours. respectively. The 2nd phase formed by the thermal diffusion of CuO from the surface leads to very excellent dielectric properties, that is,${\varepsilon}_r$ >50000, tan$\delta$ <0.05,${\Delta}C$ <${\pm}10%.$ The capacitance is almost unchanged below about 20[V] but it decreases slowly about 20[V]. The results of the capacitance-voltage properties indicated that the grain boundary was composed of the continuous insulating layers. -
The combustion characteristics of the disilicides molybdenum system have been studied experimentally. The pertinent reaction parameters that control self-propagating high temperature synthesis reactions have been examined. These include reactant particle size, powder mixing and compaction, reaction stoichiometry, diluents. The influence of experimental variables on integrity, uniformity, structure, and related material properties will be discussed. Formation mechanism of
$MoSi_2$ during SHS might be different and depending on experimental conditions. -
$(Ba_{0.6}Sr_{0.4}Ca_{x})TiO_{3}+yZrO_{2}$ wt% (x=0.10, 0.15, 0.20, y=0.5~3.0) specimens were fabricated by the mixed-oxide method and then the structural and dielectric properties as a function of the composition ratio and$ZrO_2$ contents were studied. All BSCT specimens showed dense and homogeneous structure without the presence of the seconds phase. The Curie temperature and the dielectric constant at room temperature decreased with increasing the Ca/Ba composition ratio and$ZrO_2$ content. The BSCT(50/40/10) specimens showed the excellent tunability property. And the tunability were increased with increasing the contents of$ZrO_2$ . -
For Fast Real-time Recognition of Nonlinear Error Data, a new Neural Network algorithm which recognized the map in real time is proposed. The proposed neural network technique is the real time computation method through the inter-node diffusion, In the network, a node corresponds to a state in the quantized input space. Each node is composed of a processing unit and fixed weights from its neighbor nodes as well as its input terminal. The most reliable algorithm derived for real time recognition of map, is a dynamic programming based algorithm based on sequence matching techniques that would process the data as it arrives and could therefore provide continuously updated neighbor information estimates. Through several simulation experiments, real time reconstruction of the nonlinear map information is processed,
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Experiments of 2 type on insulating compounds accomplished to change PVC using in URD(Underground) power cable jacketing. one was DB (Dielectric Breakdown) test on the pure base resins and the others were WVT(Water Vapor Transmission) test on the compounds which contained C/B(Carbon Black), anti-oxidant to base resin. a kind of specimens made by pressing to resin of pellet or lump form was HDPE(High Density Polyethylene), MDPE(Medium Density Polyehylene), LDPE(Low Density Polyethylene), LLDPE(Linear Low Density Polyethylene), PVC (Polyvinyl Chloride). As a results of AC DB and WVT test, we saw that strength of Insulation was HDPE > LLDPE ≒ MDPE > LDPE and WVT ratio was HDPE < LLDPE < MDPE < LLDPE ≒ LDPE
${\ll}$ PVC. WVT of PVC using for jacket showed characteristic 15 times more than MDPE or LLDPE. Therefore, to development of watertightness cable, our works present need of Changing in insulating materials -
CATV is the abbreviation for Cable Television. General CATV is a way of multi-channel sending images, voices and music including stillness image as well as characters to public receivers through electrical cable communication system. In the beginning, master antennas were people can not receive TV signal well. TV programs were received from master antennas to TVs in each house. Ground connection began by experimenting lightning with the use of a kite and it means electric appliances, communication equipments, measuring instruments and so on connecting the Earth in order to flow away overcharged electricity. There are two kinds of earth connection: Power Ground and Signal Ground. Power Ground is for preventing an electric shock and in general there's no current in the connector. However in an accident, there's a quick flow of electricity out to the Earth. Signal Ground is not only for the safety of appliances but also for the safety of equipment operation. This paper is about connection for noise and interference reduce in order to prevent wrong operation and distortion of signal in the electrical appliances which can take place in CATV.
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This study relates to a method for manufacturing a solid electrolytic capacitor using a functional polymer composition. The method comprises immersing the rolled aluminum electrolytic capacitor device in polyaniline solution with high electric conductivity to impregnate the device with polyaniline, drying the impregnated device in a drying oven which is maintained at constant temperature to fully remove the solvent, inserting the dried device to a capacitor aluminum can and then sealing with epoxy resin, to manufacture a solid electrolytic capacitor using a conducting polymer. As such, the impregnation can be performed well at not only normal temperature and pressure, but also high temperature and reduced pressure. The solid electrolytic capacitor has the advantages of high capacity, low impedance and low ESR, and also, low manufacturing cost, simple processes and high reliability.
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In the vector control methods of induction motor, the stator current is divided into the flux and torque component current. By controlling these components respectively, the methods control independently flux and torque as in the DC motor and improve the control effects. To apply the vector control methods, the position of the rotor current is identified. The indirect vector control use the parameters of the machine to identify the position of rotor flux. But due to the temperature rise during machine operation, the variation of rotor resistance degrades the vector control. To solve the problem, the q-axis is aligned to reference frame without phase difference by comparing the real flux component with the reference flux component. Then to compensate the slip, PI controller is used. The proposed method keeps a constant slip by compensating the gain of direct slip frequency when the rotor resistance of induction motor varies. To prove the validations of the proposed algorithm in the paper, computer simulations is executed.
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A novel water-turbine, Katamax, for micro hydropower generator is proposed, which has reasonable efficiency even in two meters of water head. The basic concept of Katamax is similar to that of waterwheel except that Katamax has two axis on which the blades rotate, where general waterwheel has only one. Brief structure and principles of Katamax are explained and analysis for efficiency of each module are provided. The result of the prototype product of Katamax is briefly explained.
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We deposited epitaxial
$Ba_{0.6}Sr_{0.4}TiO_{3}(BST)$ films having thickness of 400 nm on MgO(001) substrates, where a 10 nm thick$Ba_{1-x}Sr_{x}TiO_{3}$ (x = 0.1 - 0.7) interlayer was inserted between BST and MgO to manipulate the stress of the BST films. Since the main difference of those epitaxial BST films was the lattice constant of the interlayers, we were very successful in controlling the stress of the BST films. BST films under small tensile stress showed larger dielectric constant than that without stress as well as those under compressive stress. Stress relaxation was investigated using epitaxial BST films with various thicknesses grown on different interlayers. For BST films grown on$Ba_{0.7}Sr_{0.3}TiO_{3}$ interlayers, the critical thickness was about 600 nm. On the other hand, the critical thickness of single-layer BST film was less than 100 nm. -
Crystallographic and magnetic characteristics of CoCr-based magnetic thin film for perpendicular magnetic recording media were influenced on preparing conditions. In these, there is that substrate temperature was parameter that increases perpendicular coercivity of CoCrTa magnetic layer using recording layer. While preparation of CoCr-based doublelayer, by optimizing substrate temperature, we expect to increase perpendicular anisotropy of CoCr magnetic layer and prepare ferromagnetic recording layer with a good quality by epitaxial growth. CoCrTa/Si doublelayer showed a good dispersion angle of c-axis orientation
$\Delta\theta_{50}$ caused by inserting amorphous Si underlayer which prepared at underlayer substrate temperature 250C. Perpendicular coercivity was constant, in-plane coercivity was controlled a low value about 200Oe. This result implied that Si underlayer could restrain growth of initial layer of CoCrTa thin film, which showed bad magnetic properties effectively without participating magnetization patterns of magnetic layer. In case of CoCrTa/Si that prepared with ultra thin underlayer, crystalline orientation of CoCrTa was improved rather underlayer thickness 1nm, it was expected that amorphous Si layer played a important role in not only underlayer but also seed layer. -
The effect of silver oxide (14 wt.%) addition to YBCO compounds and electrophoretic deposition of composite particles prepared by solid phase reaction have been investigated. The results were compared with those for as-processed samples with YBCO films on Ag wire substrate. Our experiments show that the adhesion, microstructure changes, superconducting properties of these films is sensitive to the silver content and sintering conditions. Adding a small amount of PEG tends to remove cracks in the YBCO and (YBCO + Ag) films, which develop during the heating process. An attempt has been made to explain the experimental observations regarding variation of critical current density with the YBCO and (YBCO + Ag) films.
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The NdBaCuO superconductor samples were Zone-melted in low oxygen partial pressure (1%
$O_{2}+ 99% Ar$ ). The Zone-melting temperature was decreased about$120^{\circ}C$ from$1060^{\circ}C$ the zone-melting temperature in air. Thus the loss of liquid phase ($BaCuO_{2}$ and CuO) was reduced during the zone-melting process. The content of non-superconducting phase Nd422 in zone-melted NdBaCuO samples was clearly decreased, so was the substitution of Nd for Ba. The superconductivity of zone-melted$Nd_{1+x}Ba_{2-x}Cu_{3}O_{y}$ prepared under low oxygen partial pressure was distinctively improved. -
In this paper, we studied on drilling a microscopic hole of glass using electro-chemical discharge methode. In this research, we fabricated a electro-chemical discharge machine for drilling glass hole. The used parameters to get a fine microscopic hole are the concentration of NaOH solution from 5wt% to 50wt%, the supply voltage from 10V to 40V and the fabricating time from 5 second to 50 second. Also, we used a 0.16mm glass plate. We learned from our experiment that, the fabrication most efficient when supply voltage is 25V-30V and concentration of NaOH solution 35wt% or less.
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We have reported to make nanostructured cobalt oxide electrode that have large capacitance over than 400F/g (specific capacitance) and good cycleability. But, It had serious demerits of low voltage range under 0.5V and low power density. Therefore, we need to increase voltage range of cobalt oxide electrode. we report here on the electrochemical properties of sol-gel-derived nanoparticulate cobalt xerogel in 1M KOH solution and aqueous polymeric gel electrolyte. In solution electrolyte, cobalt oxide electrode had over than 250F/g capacitance consisted of EDLC and pseudocapacitance. In gel electrolyte, cobalt oxide electrode had around l00F/g capacitance. This capacitance was only surface EDLC. In solution electrolyte, potassium ion as working ion reacted with both of layers easily. However, In gel electrolyte, reacted with only surface-active layer. Its very hard to reach resistive layer. So, we have studied on pretreatment of electrode to contain working ions easily. We'll report more details.
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This paper presents the characteristics of Ta-N thin-film strain gauges as high-temperature strain gauges, which were deposited on Si substrate by DC reactive magnetron sputtering in an argon-nitrogen atmosphere(Ar-(4~16%)
$N_2$ ). These films were annealed for 1 hour in$2{\times}10^{-6}$ Torr vaccum furnace range$500\sim1000^{\circ}C$ . The optimized conditions of Ta-N thin-film strain gauges were annealing condition($900^{\circ}C$ , 1 hr.) in 8%$N_2$ gas flow ratio deposition atmosphere. Under optimum conditions, the Ta-N thin-films for strain gauges is obtained a high resistivity,$\rho=768.93$ ${\mu}{\Omega}cm$ , a low temperature coefficient of resistance, TCR=-84 ppm/$^{\circ}C$ and a high temporal stability with a good longitudinal gauge factor, GF=4.12. -
Suspension effect has been studied by using superconductor of BiPbSrCaCuO ceramics containing
$Ag_{2}O$ It has been cleared that$Ag_{2}O$ acts as pinning center which plays an important role to the suspension effect. Magnetic repulsive force which affects a superconductor located in magnetic flux from toroidal magnet has been investigated. It has been concluded that the suspension effect arises from the interaction between the pinning effect and the diamagnetic effect. -
The fabricated La-modified lead titanate (PLT) thin flim without paling treatment was investigated for modulation frequency dependence of pyroelectric properties by the dynamic method.
$Pb_{1-x}La_{x}Ti_{1-x/4}O_{3}$ PLT (x=0.1) thin film having 10 mol% La content was deposited on a$Pt/TiO_{x}/SiO_{2}/Si$ substrate by sol-gel method. The PLT(10) thin film exhibits a relatively excellent dielectric property. The pyroelectric coefficient (p) of the PLT(10) thin film is$6.6{\times}10^{-9}C/cm_{2}\cdot K$ without frequency dependence. The figure of merits for the voltage responsivity and specific detectivity are$1.03{\times}10^{-11}C\cdot cm/J$ and$1.46\times 10^{-9}C\cdot cm/J$ , respectively. The PLT(10) thin film has voltage responsivity (Rv) of 5.15 V/W at 8 Hz. Noise equivalent power (NEP) and specific detectivity (D*) of the PLT(10) thin film are$9.93{\times}10^{-8}W/Hz^{1/2}$ and$1.81\times 10^{6}cmHz^{1/2}/W$ at the same frequency of 100 Hz, respectively. The results means that PLT thin film having 10 mol % La content is suitable for the sensing materials of pyroelectric IR sensors. -
ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique for light emitting device applications. We have controlled the emission intensity of UV and visible light, depending on film thickness and various post-annealing time. UV emission became strong as the thickness of ZnO thin films increased. The intensity of visible light was strong as post-annealing temperature increased. The optical properties of the ZnO thin films were characterized by PL(photoluminescence) and the structural properties of the ZnO were characterized by XRD for the application of ZnO light emission device.
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Organic Electroluminescence device, which have the single-layer structure of ITO(indium-tin-oxide)/MEH-PPV (Poly[2-(2'-ethylhexyloxy )-5-methoxy-1,4-pheny lenevinylene])/Al(aluminium) and ITO/MEH-PPV/
$Alq_3$ (tris-8-hydroxyquinolinato aluminium)/Al were fabricated and electrical properties were investigated. Experimental results, in single-layer structure, shown that turn on voltage is about 12 V, and current density increases as a function of increasing temperature. It was explained by thermionic emission. In double-layer structure, thickness$200\AA$ of$Alq_3$ is shown electrical properties that turn on voltage is about 11 V, and current density decreases as a function of increasing temperature. ࠀ Ȁ 耀 Ѐ -
Liquid Crystal Alignment Effects on the New Homopolymerized N-(phenyl)maleimide Photopolymer SurfaceA new photoalignment material PFCPMI, poly[4-(fluorocinnamate)phenylmaleimide], was synthesized and the nematic liquid crystal (NLC) aligning capabilities on the photopolymer surface. The NLC pretilt angle generated by non-UV filter method on the PFCPMI surface was higher than that of the UV filter method. A good LC alignment by non-UV filter method was observed at
$150^{\circ}C$ of annealing temperature. However, the alignment defect of the NLC by UV filter method was measured above$150^{\circ}C$ of annealing temperature. Consequently, the high pretilt angle and the good LC alignment in NLC using non-UV filter method can be acheived. -
We study the feasibility of synthesizing Si particles using PLA method. In the previous studies, it was possible to control the size of Si nanoparticles by the He gas pressure. In this study, we fabricated sub-micron size Si particles with various shapes such as conical, hexagonal, and ring by controlling not only the ambient gas pressure but also the laser energy density. Furthermore, we found that the conical Si particles were uniform-sized and had step shape when observed from FE-SEM and AFM. The conical Si particle has the same crystal structure as the bulk single crystalline Si by the analysis of the Raman scattering. It is shown that the relationship between the laser energy density and the He gas pressure inside the chamber affects the shape of the Si particle.
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A p-n junction was obtained by the deposition of an n-type ZnO thin film on a p-type Zn-doped InP substrate. The Zn-doped InP substrate has been made by the diffusion of Zn with sealed ampoule technique. The ZnO deposition process was performed by pulsed laser deposition (PLD). The p-n junction was formed and showed a typical I-V characteristic. We will also discuss about the realization of an ultraviolet light-emitting diode (LED). The structure of n-ZnO/p-Zn-doped InP could be a good candidate for the realization of an ultraviolet light-emitting diode or an ultraviolet laser diode.
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We have investigated current-voltage (I-V) characteristics of organic light-emitting diodes based on
$TPD/Alq_3$ organics depending on the application of forward-reverse bias voltage. Luminance-voltage characteristics and luminous efficiency were measured at the same time when the I-V characteristics were measured. We have observed that the I-V characteristics shows a current mxima at low voltage, which is possibly not related to the emission from$Alq_3$ . -
In this paper, we investigated the diffraction efficiency of polarization holography using by amorphous
$Ag/As_{40}Ge_{10}Se_{15}S_{35}$ multi-layer thin films by He-Ne laser. Multi-layer structures were formed by alternating a layer of meta1(Ag) and chalcogenide($Ag/As_{40}Ge_{10}Se_{15}S_{35}$ ). The holographic grating in these thin flims has been formed using a linealy polarized He-Ne laser light (633nm). The diffraction efficiency was investigated the two sample of$Ag/As_{40}Ge_{10}Se_{15}S_{35}-7$ layers and$Ag/As_{40}Ge_{10}Se_{15}S_{35}-15$ layers. As the results, we found that the diffraction efficiency of$Ag/As_{40}Ge_{10}Se_{15}S_{35}-7$ layers and$Ag/As_{40}Ge_{10}Se_{15}S_{35}-15$ layers were 1.7% and 2.5% respectively. -
To improve structural properties and induce higher conductivity, we have annealed emitting layer. The temperature condition was investigated by various experiment. To observe the surface morphology of emitting layer, measured the AFM and the X -ray diffraction pattern of P3HT film is shown. It is move to slightly low angles and diffraction peaks also become much sharper. After annealing of emitting layer, EL intensity and Voltage-current-luminance curve is better as compared with untreated. But PL intensity was decreased. It is known that by emission principal. After annealing of emitting layer, EL devices enhances the interface adhesion between the emissive polymer and Indium-tin-oxide electrode, which takes a critical role to improve the emitting properties of EL devices.
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An accurate cross sections set are necessary for the quantitatively understanding and modeling of plasma phenomena. By using the electron swarm method. we determine an accurate electron cross sections set for objective atoms or molecule at low electron energy range. In previous paper, we calculated the electron transport coefficients in pure
$CF_4$ molecular gas by using two-term approximation of the Boltzmann equation. And by using this simulation method. we confirmed erroneous calculated results of transport coefficients for$CF_{4}$ molecule treated in this paper having 'C2v symmetry' as$C_{3}H_{8}$ and$C_{3}F_{8}$ which have large vibrational excitation cross sections which may exceed elastic momentum transfer cross section. Therefore, in this paper, we calculated the electron transport coefficients(W and$ND_L$ ) in pure$CF_4$ gas by using multi-term approximation of the Boltzmann equation by Robson and Ness which was developed at lames-Cook university, and discussed an application and/or validity of the calculation method by comparing the calculated results by two-term and multi-term approximation code. -
A large area plasma source using parallel
$2{\times}2$ ICP antennas showed improved etching uniformity by the E-ICP operation. ITO etching process with$CH_4$ gas chemistry is optimized with the DOE (Design of Experiment) based on Taguchi method. Various methane ratios in methane and argon mixture are compared to confirm the effect of polymerization. The analysis shows that the effect of bias power is the largeset. We obtained higher ITO etching rate and better uniformity on$350{\times}300mm$ substrate at the 50Hz magnetization frequency of the E-ICP operation technique, -
In this paper, aging diagnosis method of CV cable was investigated. CV cable was designed for the sake of using during 30 years. Therefore it was important to evaluate the cable's remaining life because CV cable used for power transmission line since 1970's. CV cable was mainly installed at the underground owing to the environmental condition. If the cable accident occurred, it needs the much time for the accident recovery and the much damage at the industrial activity. therefore, this paper should study the direct leakage current method, a sort of the cables' aging test method
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Maximum Power Point Tracking(MPPT) is used in wind power generation systems to maximize wind power turbin output power, irrespective of wind speed conditions and of the load electrical characteristics. In this paper we do the equivalent modeling the mechanical energy of wind power turbine according to wind speed into the synchronous generator. We analyse the equivalent modeling output part of rectifier into DC/DC converter input part theoretically. We design a control algorithm for variable voltage according to wind speed intensity and density so that load voltage of chopper is controlled steadily using the maximum power point tracking (MPPT) control method. We analyse a battery charging characteristics and a charging circuit for power storage enabling the supply of stable power to the load. We design a system and do the modeling of it analytically so that it supplies a stable power to the load by constructing a DC-AC inverter point. Also we design a charging circuit usable in actual wind power generation system of 30kW and confirm its validity.
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The molten carbonate fuel cell has conspicuous feature and high potential in being used as an energy converter of various fuel to electricity and heat. However, the MCFC which use strongly corrosive molten carbonate at
$650^{\circ}C$ have many problem. Systematic investigation on corrosion behavior of Fe/20Cr/Ti alloys has been done in (62+38)mol% (Li+K)C03 melt at 923K by using steady state polarization and electrochemical impedance spectroscopy method. And, The research and development for the solid oxide fuel cell have been promoted rapidly and extensively in recent years, because of their high efficiency and future potential. Therefore this paper describes the manufacturing method and characteristics of anode electrode for SOFC, by the way, Ni-YSZ materials are used as anode of SOFC widely. So in this experiments, we investigated the optimum content of Ni, by the impedance characteristics, overvoltage. As a result, the performance of Ni-YSZ anode(40vol%) was better excellent than the others. -
The stochiometric mix of evaporating materials for the
$ZnGa_{2}Se_{4}$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films,$ZnGa_{2}Se_{4}$ 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). The carrier density and mobility of$ZnGa_{2}Se_{4}$ single crystal trun films measured from Hall effect by van der Pauw method are$9.63{\times}10^{17}cm^{-3}$ ,$296cm^{2}/V{\cdot}s$ at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c axis of the$ZnGa_{2}Se_{4}$ single crystal thin film, we have found that the values of spin orbit splitting$\Delta$ So and the crystal field splitting$\Delta$ Cr were 251.9 meV and 183.2 meV at 10 K, respectively. From the photoluminescence measurement on$ZnGa_{2}Se_{4}$ single crystal thin film, we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton$(A^{0},X)$ having very strong peak intensity. Then, the full-width-at -half-maximum(FWHM) and binding energy of neutral acceptor bound excition were 11 meV and 24.4 meV, respectivity. By Haynes rule, an activation energy of impurity was 122 meV. -
The stochiometric mix of evaporating materials for the
$CdGa_{2}Se_{4}$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films,$CdGa_{2}Se_{4}$ 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$630^{\circ}C$ and$420^{\circ}C$ , respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of$CdGa_{2}Se_{4}$ single crystal thin films measured from Hall effect by van der Pauw method are$8.27{\times}10^{17}cm^{-3},345cm^{2}/V{\cdot}s$ at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the$CuInSe_{2}$ single crystal thin film, we have found that the values of spin orbit splitting$\Delta$ So and the crystal field splitting$\Delta$ Cr were 106.5 meV and 418.9 meV at 10 K, respectively. From the photoluminescence measurement on$CdGa_{2}Se_{4}$ single crystal thin film, we observed free excition (Ex) existing only high Quality crystal and neutral bound exiciton$(D^{0},X)$ having very strong peak intensity. Then, the full-width-at-half-maximum(FWHM) and binding energy of neutral donor bound excition were 8 meV and 13.7 meV, respectivity. By Haynes rule, an activation energy of impurity was 137 meV. -
Chemical mechanical polishing(CMP) process has been widely used to planarize dielectrics and metal, which can apply to employed in integrated circuits for sub-micron technology. Despite the increased use of CMP process, it is difficult to accomplish the global planarization of free-defects in inter level dielectrics and metal. Especially, defects like (micro-scratch) lead to severe circuit failure, and affects yield. Current conditioning method - bladder type, orbital pad motion- usually provides unsuitable pad profile during ex-situ conditioning near the end of pad life. Since much of the pad wear occurs by the mechanism of bladder type conditioning and its orbital motion without rotation, we need to implement new ex-situ conditioner which can prevent abnormal regional force on pad caused by bladder-type and also need to rotate the pad during conditioning. Another important study of ADPC is related to the orbital scratch of which source is assumed as diamond grit dropped from the strip during ex-situ conditioning. Scratch from diamond grit damaged wafer severely so usually scraped. Figure 1 shows the typical shape of scratch damaged from diamond. e suspected that intensive forces to the edge area of bladder type stripper accelerated the drop of Diamond grit during conditioning. so new designed Flat stripper was introduced.
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There are several factors causing re-work in CMP process such as improper polish time calculation by operator. removal rate decline of the polisher, unstable in-suit pad conditioning, slurry supply module problem and wafer carrier rotation inconsistancy. And conclusively those fundimental reason for the re-work rate increasement is mainly from the cycle time delay between wafer polish and post measurement. Therefore, Wafer thickness measurement in wet condition could be able to remove those improper process conditions which may happen during the process in comparison with the conventional dried wafer measurement system and it can be able to reduce the CMP process cycle time. CMP scrap reduction by overpolish, re-work rate reduction, thickness control efficiency also can be easily achieved. CMP Equipment manufacturer also trying to develop integrated system which has multi-head & platen, cleaner, pre & post thickness measure and even control the polish time from the calculated removal rate of each polishing head by software. CMP re-work problem such as over & under polish by target thickness may result in the cycle time delay. By reducing those inefficient factors during the process and establish of the automatic process control, CLC system need to be adopted to maximize the process performance. Wafer to Wafer Polish Time Feed Back Control by measuring the wafer right after the polish shorten the polish time calculation for the next wafer and it lead to the perfact Post CMP target thickness control capability. By Monitoring all of the processed the wafer, CMP process will also be stabilize itself.
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Chemical Mechanical Polishing(CMP) of Shallow Trench Isolation(STD structure in 0.18 m semiconductor device fabrication is studied. CMP process is applied for the STI structure with and without reverse moat pattern and End Point Detection (EPD) method is tested. To optimize the transistor properties related metal 1 parameters. we studied the correlation between CMP thickness of STI using high selectivity slurry. DOE of gate etch recipe, and 1st metal DC values. Remaining thickness of STI CMP is proportional to the thickness of gate-etch process and this can affect to gate profile. As CMP thickness increased. the N-poly foot is deteriorated. and the P-Poly Noth is getting better. If CD (Critical Dimension) value is fixed at some point,, all IDSN/P values are in inverse proportional to CMP thickness by reason of so called Profile Effect. Weve found out this phenomenon in all around DOE conditions of Gate etch process and we also could understand that it would not have any correlation effects between VT and CMP thickness in the range of POE 120 sec conditions. As CMP thickness increased by
$100\AA$ . 3.2$u\AA$ of IDSN is getting better in base 1 condition. In POE 50% condition. 1.7$u\AA$ is improved. and 0.7$u\AA$ is improved in step 2 condition. Wed like to set the control target of CD (critical dimension) in gate etch process which can affect Idsat, VT property versus STI topology decided by CMP thickness. We also would like to decide optimized thickness target of STI CMP throughout property comparison between conventional STI CMP with reverse moat process and newly introduced STI CMP using high selectivity slurry. And we studied the process conditions to reduce Gate Profile Skew of which source known as STI topology by evaluation of gate etch recipe versus STI CMP thickness. -
Kim, Sang-Yong;Park, Sung-Woo;Jeong, So-Young;Lee, Woo-Sun;Kim, Chang-Il;Chang, Eui-Goo;Seo, Yong-Jin 185
Chemical mechanical polishing(CMP) process is widely used for global planarization of inter-metal dielectric (IMD) layer and inter-layer dielectric (ILD) for deep sub-micron technology. However, as the IMD and ILD layer gets thinner, defects such as micro-scratch lead to severe circuit failure, which affect yield. In this paper, for the improvement of CMP process, deionized water (DIW) pressure, purified$N_2 \; (PN_2)$ gas, slurry filter and high spray bar were installed. Our experimental results show that DIW pressure and$PN_2$ gas factors were not related with removal rate, but edge hot-spot of patterned wafer had a serious relation. Also, the filter installation in CMP polisher could reduce defects after CMP process, it is shown that slurry filter plays an important role in determining consumable pad lifetime. The filter lifetime is dominated by the defects. However, the slurry filter is impossible to prevent defect-causing particles perfectly. Thus, we suggest that it is necessary to install the high spray bar of de-ionized water (DIW) with high pressure, to overcome the weak-point of slurry filter. Finally, we could expect the improvements of throughput, yield and stability in the ULSI fabrication process. -
Kim, Hyung-Gon;Kim, Chul-Bok;Kim, Sang-Yong;Lee, Cheol-In;Kim, Tae-Hyung;Chang, Eui-Goo;Seo, Yong-Jin 189
Recently, STI process is getting attention as a necessary technology for making high density of semiconductor by devices isolation method. However, it does have various problems caused by CMP nprocess, such as torn oxide defects, nitride residues on oxide, damages of si active region, contaminations due to post-CMP cleaning, difficulty of accurate end point detection in CMP process, etc. In this work, the various defects induced by CMP process was introduced and the above mentioned problems of CMP process was examined in detail. Finally, the guideline of future CMP process was presented to reduce the effects of these defects. -
Single phase
$CuInS_2$ thin film with the highest diffraction peak (112) at diffraction angle$(2\theta)$ of$27.7^{\circ}$ and the second highest diffraction peak (220) at diffraction angle$(2\theta)$ of$46.25^{\circ}$ was well made with chalcopyrite structure at substrate temperature of$70^{\circ}C$ , annealing temperature of$250^{\circ}C$ , annealing time of 60 min. The$CuInS_2$ thin film had the greatest grain size of$1.2{\mu}m$ and Cu/In composition ratio of 1.03. Lattice constant of a and c of that$CuInS_2$ thin film was 5.60 A and 11.12 A respectively. Single phase$CuInS_2$ thin films were accepted from Cu/In composition ratio of 0.84 to 1.3. P-type$CuInS_2$ thin films were appeared at over Cu/In composition ratio of 0.99. Under Cu/In composition ratio of 0.96, conduction types of$CuInS_2$ thin films were n-type. Also, fundamental absorption wavelength, the absorption coefficient and optical energy band gap of p-type$CuInS_2$ thin film with Cu/In composition ratio of 1.3 was 837 nm,$3.0{\times}104cm^{-1}$ and 1.48 eV respectively. When Cu/In composition ratio was 0.84, fundamental absorption wavelength, the absorption coefficient and optical energy band gap of n-type$CuInS_2$ thin film was 821 nm,$6.0{\times}10^4cm^{-1}$ and 1.51 eV respectively. -
In this letter, we report on the investigation of Ni/Si/Ni Ohmic contacts to n-type 4H-SiC. Ohmic contacts have been formed by a vacuum annealing and
$N_2$ gas ambient annealing method at$950^{\circ}C$ for 10 min. The specific contact resistivity ($\rho_{c}$ ), sheet resistance($R_s$ ), contact resistance($R_c$ ), transfer length($L_T$ ) were calculated from resistance($R_T$ ) versus contact spacing(d) measurements obtained from 10 TLM(transmission line method) structures. The resulting average values of vacuum annealing sample were$\rho_{c}=3.8{\times}10^{-5}\Omega cm^{3}$ ,$R_{c}=4.9{\Omega}$ ,$R_{T}=9.8{\Omega}$ and$L_{T}=15.5{\mu}m$ , resulting average values of another sample were$\rho_{c}=2.29{\times}10^{-4}\Omega cm^{3}$ ,$R_{c}=12.9{\Omega}$ and$R_{T}=25.8{\Omega}$ . The physical properties of contacts were examined using X-Ray Diffraction and Auger analysis, there was a uniform intermixing of the Si and Ni, migration of Ni into the SiC. -
In this paper, for modeling of electrical characteristics in Poly Silicon Thin Film Transistors with process parameters set up optimum values, So, the I-V characteristics of poly silicon TFT parameters are examined and simulated in terms of the variations in process parameter. And these results compared and analyzed simulation values with examination value. The simulation program for characteristic analysis used SUPREM IV for processing, Matlab for modeling by mathematics, and SPICE for electric characteristic of devices. Input parameter for simulation characteristics is like condition of device process sequence, these electric characteristic of
$I_D-V_D$ $I_D-V_G$ , variations of grain size. The Gate oxide thickness of poly silicon are showed similar results between real device characteristics and simulation characteristics. -
Steady state and transient thermal analysis has been done by a finite element method in a diode of 12kV blocking voltage for microwave oven. 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 copper 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 and epoxy with a thickness of
$25{\mu}m$ and$3700{\mu}m$ , respectively. The chip size, thickness and material properties were very important factor for high voltage diode package. And also, thermal stress value was highest in the edge of diode and solder. So, design of edge in silicon was very important to thermal stress. -
Polyimide(PI) films have been considered as the interlayer dielectric materials due to low dielectric constant, low water absorption, high gap-fill and planarization capability. The PI mm Was etched with using inductively coupled plasma (ICP). The etching characteristics such as etch rate and selectivity were evaluated to gas mixing ratio. High etch rate was
$8300{\AA}/min$ and vertical profile was approximately acquired$90^{\circ}$ at$CF_{4}/(CF_{4}+O_{2})$ of 0.2. The selectivies of polyimide to PR and$SiO_{2}$ were 1.2, 5.9, respectively. The etching profiles of PI films with an aluminum pattern were measured by a scanning electron microscope (SEM). The chemical states on the PI film surface were investigated by x-ray photoelectron spectroscopy (XPS). Radical densities of oxygen and fluorine in different gas mixing ratio of$O_{2}/CF_{4}$ were investigated by optical emission spectrometer (OES). -
Etching behaviors of ferroelectric
$YMnO_3$ thin films were studied by an inductively coupled plasma (ICP). Etch characteristic on ferroelectric$YMnO_3$ thin film have been investigated in terms of etch rate, selectivity and etch profile. The maximum etch rate of$YMnO_3$ thin film is$300{\AA}/min$ at$Ar/Cl_2$ of 2/8, RF power of 800W, dc bias voltage of 200V, chamber pressure of 15mTorr and substrate temperature of$30^{\circ}C$ . Addition of$CF_4$ gas decrease the etch rate of$YMnO_3$ thin film. From the results of XPS analysis, YFx compounds were found on the surface of$YMnO_3$ thin film which is etched in$Ar/Cl/CF_{4}$ plasma. The etch profile of$YMnO_3$ film is improved by addition of$CF_4$ gas into the$Ar/Cl_2$ plasma. These results suggest that fluoride yttrium acts as a sidewall passivants which reduce the sticking coefficient of chlorine on$YMnO_3$ . -
The possibility of cerium dioxide
$(CeO_2)$ thin films as insulators of metal erroelectric insulator semiconductor (MFIS) structures have been studied. The etching$CeO_2$ thin films have been perfonned in an inductively coupled$Cl_{2}/CF_{4}/Ar$ plasma. The high etch rate of the$CeO_2$ thin film was$250\AA /m$ at a 10 % addition of$Cl_2$ into the$Ar(80)/CF_{4}(20)$ . The surface reaction of the etched$CeO_2$ thin films was investigated using X-ray photoelectron spectroscopy (XPS) analysis. There are Ce-Cl and Ce-F bonding by chemical reaction between Cl, F and Ce. These products can be removed by the physical bombardment of incident Ar ions. -
In the paper, we report on the DC and Thermal effect of the GaN based HFET. A physics-based a model was applied and found to be useful for predicting the DC performance and Thermal effect of the GaN based HFET by Various substrate. The performance of device on the sapphire substrates is found to be significantly improve compared with that of a device with an sapphire substrate. The peak drain current of the device achieved at HFET on the SiC substrate
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To achieve ZnO layer with a high resistance, a new sputtering method with a Ramp method and cycled power process mode was developed. The specific resistance of the layers was in rang of
$3*10^{10}{\Omega}cm$ to$2*10^{11}{\Omega}cm$ . The characteristics of. ZnO thin films changed with working pressure and Ramp method were investigated by XRD(x-ray diffractometer), and SEM (scanning electron microscopy) analyses. This paper presents calculated and measured results for structures with thin ZnO layers. Measurements of SAW properties using thin ZnO layered structures will be shown. Also presented are results on the quality of ZnO films and specifics of the deposition process. -
FeSi2/Si Layer were grown using FeSi2, Si wafer by the chemical transport reactio nmethod. The directoptical energy gap was found to be 0.871eV at 300 K. The Hall effect is a physical effect arising in matter carrying electric current inthe presence of a magnetic field. The effect is named after the American physicist E. H. Hall, who discovered it in 1879. IN this paper, we study electrical properties of FeSi2/Si layer. And then we measured Hall coefficient Hall mobility, carrier density and Hall voltage according to variation magnetic field and temperature, Because of important part for it applicationVarious phase of silicide is formed at the metal-Si interface when transition metal contacts to Si. Silicides belong to metallic or semiconducting according to their electrical and optical properties. Metallic silicides are used as gate electrodes or interconnections in VLSI devices. Semiconducting silicides can be used as a new material for IR detectors because of their narrow energy band gap.
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FeSi2/Si Layer were grown using FeSi2, Si wafer by the chemical transport reactio nmethod. The directoptical energy gap was found to be 0.871eV at 300 K. The Hall effect is a physical effect arising in matter carrying electric current inthe presence of a magnetic field. The effect is named after the American physicist E. H. Hall, who discovered it in 1879. IN this paper, we study electrical properties of FeSi2/Si layer. And then we measured Hall coefficient Hall mobility,carrier density and Hall voltage according to variation magnetic field and temperature, Because of important part for it applicationVarious phase of silicide is formed at the metal-Si interface when transition metal contacts to Si. Silicides belong to metallic or semiconducting according to their electrical and optical properties. Metallic silicides are used as gate electrodes or interconnections in VLSI devices. Semiconducting silicides can be used as a new material for IR detectors because of their narrow energy band gap.
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In this paper, the current-voltage characteristics of a 4H-SiC MESFET is simulated by using the Atlas Simulation tool. we are able to use the simulator to extract more information about the new material 4H-SiC, including the mobility, velocity-field Curve and the Schottky barrier height. We have enabled and used the new simulator to investigate breakdown Voltage and thus predict operation limitiations of 4H-SiC device. Modeling results indicate that the Breakdown Voltage is 197 V and Current is 100 mA
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In this paper, we have proposed a novel trench electrode Base Resistance Thyristor(BRT) and trench electrode BRT with a intrinsic region. A new power BRTs have shown superior electrical characteristics including snab-back effict and forward blocking voltage more than the conventional BRT. Especially, the trench electrode BRT with intrinsic region has obtained high blocking voltage of 1600V. The blocking voltage of conventional BRT is about 400V at the same size. Because the breakdown mechanism of BRT is avalanch breakdown by impact ionization, the trench electrode BRT with intrinsic region has suppressed impact ionization, effectively. If we use this principle, we can develope super high voltage power devices and applicate to another power devices including IGBT, EST and etc.
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We studied optical properties of SiON thin-film in the applications of optical waveguide. SiON thin-film was grown in
$300^{\circ}C$ by PECVD(plasma enhanced chemical vapor deposition) system. The change of SiON thin-film composition and refractive Index was studied as a function of varying$NH_3$ gas flow rate. As$NH_3$ gas flow rate was increased, Quantity of N and refractive index were increased at the same time. By the results, we could form the SiON thin-film to use of a waveguide with refractive index of 1.6. We analyzed the conditions of the thin-film with FTIR(fourier transform infrared) and OES (optical emission spectroscopy). N-H bonding($3390cm^{-1}$ ) can be removed by thermal annealing. And we could observe the SiH bonding state and quantity by OES analysis in$SiH_4$ -
In this paper, we analyzed the properties change of electric wire when the thermal stress was applied to NFR-8 and FR-PVC 600[V] wire. Messurement is made of the attenuation of a light beam by smoke accumulating with in a closed chamber due to nonflaming pyrolytic decomposition and flaming combustion. Results are expressed in terms of specific optical density which is derived from a geometrical factor and the measured optical density a measurement characteristic of the concentration of smoke. Referenced documents were ASTM E662 standard test method for specific Ds genalated by solid materials. The furnace control system shall maintain the required irradiance level under steady-state condition with the chamber door closed of
$2.5{\pm}0.04[w/cm^{2}]$ for 20 min. According to the results of the smoke density analysis of NFR-8 and FR-PVC the highest decomposition flaming smoke density range of NFR-8 and FR-PVC were 25.2 to 37.5 and 51.1 respectively. Nonflaming smoke density range of NFR-8 and FR-PVC were 100.4 to 112.2 and 126.5 to 398.8. The amount of carbon monoxide generated was found to be much higher in FR-PVC decomposition than in NFR-8 due to incomplete combustion of FR-PVC which has high content of carbon in compound. -
In this paper, the silicon rubber insulator for transmission line was experimented for 1,000 hours aging test in salt-fog condition. To evaluate and examine the aging properties of silicon rubber insulator for test, the leakage current of surface was measured. Also hydrophobicity and scanning electron microscopy were compared with initial and aged sample respectively. Above results, we can confirm that the surface properties of silicon rubber insulator easily aged by salt-fog condition.
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In this paper, aging characteristics of silicone rubber used for outdoor insulation have been investigated with regards to salt fog condition and heat aging effect. We look over the change of properties 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,
$Al_2O_3{\cdot}3H_2O$ ) filler contents. Surface resistivity, SEM(Scanning Electro Microscope) were measured. -
In order to investigate the water tree degradation behavior on XLPE cable, direct voltage of 200 to 800V has been applied to the material at
$50^{\circ}C\sim100^{\circ}C$ . and the water tree property has been correlated with voltage and temperature in this study. The leakage current was shown to increase as temperature increased and the Ohm's law was generally satisfied in this experiment though some experimental errors were found. The leakage current was shown to decrease and reach to the stable state with time. It was also shown that the time for the stabilization of leakage current was lessened as voltage increased -
This paper investigated the aging characteristic under long-term corona discharge on roan temperature vulcanized silicone rubber, which has been using as a protective coating material for solving the contaminant problem. The applied electrical field is 10kV/cm ac and corona discharge treatment was applied on RTV silicone rubber sheet for maximum 250 hours. With the duration of corona discharge. the diffusible low molecular weight species increased, which was determined the usage of n-hexane extraction method. In addition, the contaminant layer was formed on the treated surface, and then measured the contact angle. We investigated the relation of contact angle and diffusible low molecular weight species. It is found that scissor of main chain PDMS and side chains
$(CH_3)$ and the generation of LMW species were occurred by a corona discharge. The improvement of hydrophobicity rate is thought due to the increase of diffusible LMW species. -
Electrical tree is studied widely by manufacture state of insulating material fare and blazing fire diagnosis system of use in phenomenon of part discharge that happen for main cause of dielectric breakdown of equipment for electric power. Use process that draw tree pattern here measuring above zero to study special quality of this electricity tree, real-time processing by image processing is proposed because reproduction of tree blazing fire process drops and pattern of tree is difficult correct quantification of tree growth by existent visual observation by involution. This research presents general process that need in image processing of tree blazing fire, and that remove various noises that happen in above zero by measuring electrical tree dividing background and complete view in measured above zero taking advantage of specially proposed complete view object abstraction techniques effectively and quantification of tree becomes easy naturally, can apply to dielectric breakdown estimate because can chase growth process of tree.
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This paper describes the simulation study. conducted on the propagation characteristics of AE signal. In the case of gas insulation, such as
$SF_6$ , the equipment is less affected by the environment condition than air insulation, because the component parts of equipment were placed in the enclosure, which is filled with compressed gas. But. when the breakdown in the electric insulation occurs. it takes much time and economical efforts to repair. Therefore it is very important to diagnose the equipment before the accident. And. in general. UHF and AE signal is the most common transducer to diagnose the state of the power equipment, so, in this investigation, we make a experimental apparatus with aluminum plate and transient analysis with ANSYS to observe the propagation characteristics of AE signal. Through the result of the analysis. we can make a further understanding on the propagation characteristics of AE signal, and get the fundamental skills for the GIS diagnosis. -
BSCCO thin films have been fabricated by co-deposition at an ultralow growth rate using ion beam sputtering(IBS) method. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(100) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and
$820^{\circ}C$ and the highly condensed ozone gas pressure($PO_3$ ) in vacuum chamber was varied between$2.0{\times}10^{-6}$ and$2.3{\times}10^{-5}$ Torr. Bi 2212 phase appeared in the temperature range of 750 and$795^{\circ}C$ and single phase of Bi 2201 existed in the lower region than$785^{\circ}C$ . Whereas,$PO_3$ dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with$T_c$ (onset) of about 90 K and$T_c$ (zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as$CaCuO_2$ was observed in all of the obtained films. -
$Bi_{2}Sr_{2}CuO_{x}$ (Bi-2201) thin films were fabricated by atomic layer-by-layer deposition using an ion bearn sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition. two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit. then three dimensional growth takes place. Since Cu element is the most difficult to oxidize. only Sr and Bi react with each other predominantly. and forms a buffer layer on the substrate in an amorphous-like structure. which is changed to$SrBi_{2}O_{4}$ by in-situ anneal. -
Multi-pole anisotropic Sr-ferrite sintered magnets has been studied by powder injection molding under applied magnetic field. The orientation of anisotropic Sr-ferrite powders higher than 80% during injection molding is achieved at the following conditions; apparent viscosity lower then 2500 poise in 1000
$sec^{-1}$ shear rate and applied magnetic field higher then 4 kOe. For the high fluidity and strength of injection molded compact, and the effective binder removal without defects during solvent extraction and thermal debinding, the optimum multi-binder composition is paraffin wax(PW)/carnauba wax(CW)/HDPE = 50/25/25 wt%. The rate of binder removal is proportional to the mean particle size of Sr-ferrite powders whereas it is inversely proportional to the content of Sr-ferrite powders and the sample thickness. The high magnetic properties of Sr-ferrite sintered magnets are; 3.8 kG of remanent flux density, 3.4 kOe of intrinsic coercivity, and 1.2 kG of surface flux density (l-mm-thick) in the direction of applied magnetic field. -
It is very important to select suspension solution for forming electrophoretic deposited YBCO thick mm, because it is heavily affected to its superconducting properties. In this paper, high-temperature superconductor films of
$YBa_{2}Cu_{3}O_{7-x}$ were fabricated by electrophoretic deposition (EPD) from alcohol-based suspension such as iso-propanol, iso-butanol, and their mixture. For the formation of YBCO dense and adherent coating on a silver wire by EPD, 1 % PEG(1000) 2 ml, as a additive for making their surface crack-free, was used for electrophoresis. As a results, the cracks were considerably decreased and the superconducting critical current density$(J_e)$ without/with PEG was$1200A/cm^2$ and$2020A/cm^2$ , which films deposited in mix iso-propanol and iso-butanol suspension. -
The NdBaCuO superconducting samples were prepared by the Zone melting under low oxygen partial pressure. After the zone-melting the oxygenation process of the NdBaCuO samples in a oxygen flow furnace was studied. In order to compare the oxygenation condition the sintering NdBaCuO samples were studied also. In the study it is found that the optimum temperature for the oxygenation is
$350^{\circ}C$ , and the oxygen flow speed, the sample volume and the surface area of the sample would influence the oxygenation and the oxygen content. -
Data on the oil spill recovery from the water surface by light floating electromagnetic plants using a new magnetic adsorbent are given. The feasibility scope for further oil recovery from such gathered mixtures(oil + adsorbent), reuse of this magnetic adsorbent and its property reclaiming and recycling were shown. The basic conception of the oil spill recovery and efficiency of this method were set forth.
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BSCCO thin films are fabricated via a co-deposition process by an ion beam sputtering with an ultra-low growth rate, and sticking coefficients of the respective elements are evaluated. The sticking coefficient of Bi element exhibits a characteristic temperature dependence : almost a constant value of 0.49 below
$730^{\circ}C$ and decreases linearly with temperature over$730^{\circ}C$ . This temperature dependence can be elucidated from the evaporation and sublimation rates of bismuth oxide,$Bi_{2}O_{3}$ , from the film surface. It is considered that the liquid phase of the bismuth oxide plays an important role in the Bi 2212 phase formation in the co-deposition process. -
High quality BSCCO thin films have been fabricated by means of an ion beam sputtering at various substrate temperatures,
$T_{sub}$ , and ozone gas pressures,$PO_3$ . The correlation diagrams of the BSCCO phases appeared against$T_{sub}$ and$PO_3$ are established in the 2212 and 2223 compositional films. In spite of 2212 compositional sputtering, Bi220l and Bi2223 phases as well as Bi2212 one come out as stable phases depending on$T_{sub}$ and$PO_3$ . From these results, the thermodynamic evaluations of${\Delta}H$ and${\Delta}S$ S, which are related with Gibbs' free energy change for single Bi2212 or Bi2223 phase are performed. -
Bi-2212 and Bi-2223 thin films are prepared by IBS(ion beam sputtering) technique. Three phases of Bi-2201, Bi-2212 and Bi-2223 appear as stable ones in spite of the conditions for thin film fabrication of Bi-2212 and Bi-2223 compositions, depending on substrate temperature(
$T_{sub}$ ) and ozone pressure($PO_3$ ). It is found out that these phases show similar$T_{sub}$ and$PO_3$ dependence, and that the stable regions of these phases are limited within very narrow temperature. -
Kim, Yun-Myoung;Pyo, Sang-Woo;Kim, Jun-Ho;Shim, Jae-Hoon;Zyung, Tae-Hyung;Kim, Young-Kwan;Kim, Jung-Soo 312
Recently organic electroluminescent devices have been intensively investigated for using in full-color flat-panel display. Since the quantum efficiency of electrophosphorescent device decrease rapidly as the luminance increase, it is desirable to operate the electrophosphorescent display with active matrix rather than passive matrix. Here we report the study of driving electrophosphorescent diode with all organic thin film transistor(OTFT). The structure of electrophosphorescent diode is ITO/TPD/BCP:Ir(ppy)$_3$ /BCP/Alq$_3$ /Li:Al/Al. In OTFT. polymer is used as an insulator and pentacene as an active layer. Detailed performance of the integrated device will be discussed. -
Organic light emitting diodes(OLEDs) with a hole injection layer inserted between Indium-Tin-Oxide(ITO) anode and hole transport layer were fabricated. The effect of plasma treatment on the surface properties of Indium-Tin-Oxide(ITO) anode were studied. The electrical and optical characteristics of the fabricated organic light emitting diodes(OLEDs) were also studied. The diode including of plasma treated ITO substrate and the hole injection layer, which showed the luminance of 5280
$cd/m^{2}$ at 8 V -
A computer simulation was performed to distinguish quantitatively a color reaction in a urine analysis systems by using the spectral power distribution of LEDs. the spectral reflectance of a urine strip. and the spectral sensitivity of photodiode. The CIE tristimulus values and CIE chromaticity coordinates ware modified to be conformable with real color reactions in a urine strips. Results on color simulation showed a of real color in comparison with those obtained by Colorimeter CM2C(Color Savvy).
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Liquid crystal alignments on a rubbed polyimide layer were investigated by using optical transmission method. Using this technique, we also studied the pretilt angle of the polymer molecules near the surface of a side-chain polymer layer as a function of the rubbing strength. In particular, we obtained the optical characteristics of liquid crystal orientations and pretilt angles for LC cell photo-aligned by UV as well after rubbing alignment. High pretilt angle of 3.84 degree was obtained on the weekly rubbed polymide layer duribg UV irradation time of 60min.
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Color simulation on a portable colorimeter was performed to distinguish quantitatively a chromaticity coordinates on a color guide of a urine strips by using the spectral power distribution of chip LED, the spectral reflectance of printed objects, and the spectral sensitivity of photodiode. The CIE tristimulus values and chromaticity coordinates realized by a colorimeter were modified to be conformable with real color reactions. Experimental results showed a real color in comparison with those obtained by Colorimeter CM2C(Color Savvy).
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In this study, the reaction at UBM(Under Bump Metallurgy) and solder interface was investigated. The UBM employed in conventional optical packages, Au/Pt/Ti layer, were found to dissolve into molten Au-Sn eutectic solder during reflow soldering. Therefore, the reaction with different diffusion barrier layer such as Fe, Co, Ni were investigated to replace the conventional Pt layer. The reaction behavior was investigated by reflowing the solder on the pad of the metals defined by Cr layer for 1, 2, 3, 4, and 5 minutes at
$330^{\circ}C$ . Among the metals, Co was found to be most suitable for the diffusion barrier layer as the wettability with the solder was reasonable and the reaction rate of intermetallic formation at the interface is relatively slow. -
The control of high pretilt angle far nematic liquid crystal (NLC) with negative dielectric anisotropy on the rubbed blending polyimide (homeotropic and homogeneous alignment) surface were studied. High NLC pretilt angle generated on the blending polyimide (homeotropic polyimide and SE-7492 surface was measured and the NLC pretilt angle increases with blending ratio and rubbing strength. However, the NLC pretilt angle generated on the blending polyimide (homeotropic polyimide and SE-150 surface was not varied. The high pretilt angle the NLC using blending polyimide surface can be acheived.
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In this study, nano-sized powders of
$Si0_2-0^{\sim}15mol%B_2O_3$ composition were prepared by sol-gel processing method using TEOS(Tetra ethyl ortho silicate) and$H_3BO_3$ solution. The powders were tape-cast on High silicate glass sheet(HSG) substrate and sintered to form a layer of undercladding for the planar light wave module, During the sol-gel processing,$H_2O/Si$ mole ratio were varied to modify the size of the powders in a range from 600 to 75nm. The dispersion of the powder was modified by changing the pH of the slurry. Sintering temperature of the tape was observed to decrease with the size of the powder and the$B_2O_3$ content in the powder. When the silica powders of 75-125nm in diameter containing 15mol%$B_2O_3$ were used, 98 TD% was obtained at$1250^{\circ}C$ , which is approximately$300^{\circ}C$ reduction in sintering temperature compared with micrometer-sized powders. -
We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of diamond like carbon (DLC) thin film. A high pretilt angle of about
$4^{\circ}$ was measured by ion beam(IB) exposure on the DLC thin film surface. A good LC alignment was observed by the IB alignment method on the DLC thin film surface at annealing temperature of$200^{\circ}C$ , and the alignment defect of the NLC was observed above annealing temperature of$220^{\circ}C$ . Consequently, the high NLC pretilt angle and the good thermal stability of LC alignment can be achieved by the IB alignment method on the DLC thin film surface. -
Aligning capabilities for nematic liquid crystal (NLC) using a in-situ photodimerization method on various photo-crosslinkable polyimide (PI) based polymer and blending photopolymer surfaces were stuided. High pretilt angle of the NLC can be measured by obliquely polarized UV exposure on a photo-crosslinkable polyirnide based polymer surface containing biphenyl (BP), decyl (de), and cholesteryl (chol) group, respectively, However, the low pretilt angle of the NLC was measured by obliquely polarized UV exposure on the blending photopolymer (PI and cinnamate materials) surfaces. Consequently, the pretilt angle of the NLC generated on the photo-crosslinkable polyimide based polymer surfaces using the in-situ photodimerization method was higher than that of the blending photopolymers.
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The residual DC properties in the in-plane switching (IFS) liquid crystal displays(LCDs) which have different concentrations of cynao NLCs and different resistivities of fluorine NLCs were studied. We also propose a new residual DC measurement method, named 'light minimum/maximum method'. We confirmed the precision of residual DC measurement by light minimum/maximum method compared with the flicker minimizing method and found that new measurement method of residual DC is better than that of the conventional flicker minimizing method since the resolution level of measurements is in 0.1V
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A new photoalignment material PMI5CA, poly{N-(phenyl)maleimide-co-3-[4-(pentyloxy) cinnamate]propyl-2-hydroxy-1-methacrylate}, was synthesized and the electra-optical (EO) characteristics in the vertical-aligned (VA) liquid crystal display (LCD) photo-aligned on the photopolymer surface were studied. Excellent voltage-transmittance(V-T) characteristics in the VA-LCD photoaligned with polarized UV exposure of oblique direction on the pohotopolymer surfaces for 1 min can be achieved. The transmittance of the VA-LCD photoaligned on the photopolymer surface decreased with increasing UV exposure time. We suggest that the decrease of transmittance in the VA-LCD photoaligned on the photopolymer surface is attributed to the dissociation of the ester linkage in the photodimerized cinnamate structure with increasing UV exposure time
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The chalcogenide glasses of thin films have the superior property of photoinduced anisotrophy(PA). In this study, we observed the linear dichroism(D) using the irradiation with polarized He-Ne laser light, in the
$Ag/As_{40}Ge_{10}Se_{15}S_{35}$ multi-layer. Mutilayer structures formed by alternating metal(Ag) a chalcogenide$(As_{40}Ge_{10}Se_{15}S_{35})$ . Such multilayer structures have a greater sensitivity to illumination am larger dichroism in comparison the conventional double layer structure. Also new phenomena are discovered. These results will be show a capability of new method that suggested more improvement of photoinduced anisotropy property. -
In this study, the matrix Organic Electroluminescence (OEL) device, that was consisted of R,G,B pixels. We fabricated OEL devices by side by side methode and, used organic material Alq3 as green, DCM as red and Butyl PBD as blue ETL. We investigated the characteristic of brightness and current density for matrix OEL device. As the results, each color devices has minimum about
$100cd/m^{2}$ brightness and maximum luminescence was$2500cd/m^2$ in green OEL device. -
Lee, Ho-Sik;Chung, Taekk-Gyun;Kim, Sang-Keol;Jung, Dong-Hoe;Jang, Kyung-Wook;Lee, Won-Jae;Kim, Tae-Wan;Lee, Joon-Ung;Kang, Dou-Yol 370
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 tris(8-hydroxyquinoline) aluminum($Alq_3$ ) 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. -
We have synthesized poly(3-hexylthiophene)(P3HT), which is the most famous conducting polymer and studied the optical properties of P3HT. And then fabricated the device using P3HT as an emitting layer. For the improve of hole injection from ITO electrode to P3HT emitting layer, we use transparent polyaniline(PANI) electrode. In the voltage-current-luminance characteristics of ITO/PANI/P3HT/LiF/Al device which use the PANI film synthesised during 5 cycle, the device turn on at the 2V and the luminance of
$218nW/cm^{2}$ obtained at 12V. External quantum efficiency of ITO/PANI/P3HT/LiF/Al increased at 8V than that of ITO/P3HT/LiF/Al device. -
Cho, Jong-Rae;Jeong, Jae-Hoon;Moon, Jeong-Oh;Yang, Jong-Hyun;Son, Se-Mo;Kim, Kang-Eun;Chung, Su-Tae 378
The electron drift mobility of poly(4,4'-cyclohexylidenediphenyl carbonate) (PC-Z) doped with 3,5-dimethy-3,5-di-t-butylstilbenequinone(MBSQ), 3,5,3,5-tetra-t-butyl stilbenequinone(TBSQ) and 3,5,3,5-tetra-methyl stilbenequinone(TMSQ) was measured by the time-of-flight technique. The electric field and temperature dependences of the electron drift mobility were discussed with Poole-Frenkel, Arrhenius formulations and non-Arrhenius type of temperature dependence. It was assumed that the hopping sites were Gaussian distribution. Mobility and activation energy of MBSQ were increased with increasing dopant. However, mobilities and activation energy of TBSQ and TMSQ were increased and decreased, respectively. -
In the previous study, a new LTCC material in the
$PbWO_{4}-TiO_{2}-B_{2}O_{3}-CuO$ system was introduced. The developed material can be sintered at$850^{\circ}C$ and its dielectric properties are$\varepsilon_{r}=20-25$ ,$Q{\times}f_{o}=30000\sim50000GHz$ , and$\tau_{f}=0.2{\sim}30ppm/^{\circ}C$ , respectively. Therefore this material can be used as a LTCC substrate material for fabrication of multilayered high frequency communication module set. In present study, using this material, tape casting condition was established. With this condition, a multilayered resonator was fabricated and its electrical properties were examined. In present study, an antenna-duplexer module was also fabricated. Frequency characteristics of as-fabricated antenna-duplexer module was compared with simulation results. -
In this study, development of a new LTCC material using non-glassy system was attempted with repsect to reducing the fabrication process steps and cost down. Lowering the sintering temperature can be achieved by liquid phase sintering. However, presence of liquid phases usually decrease dielectric properties, especially the quality factor. Therefore, the starting material must have quality factor as high as possible in microwave frequency range. And also, the material should have a low dielectric constant for enhancing the signal propagation speed. Regarding these factors, dielectric constants of various materials were estimated by the Clausius-Mosotti equation. Among them,
$ZnWO_4$ was turned out the suitable LTCC material.$ZnWO_4$ can be sintered up to 98% of full density at$1050^{\circ}C$ for 3 hours. It's measured dielectric constant, quality factor, and temperature coefficient of resonant frequency were 15.5, 74380GHz, and$-70ppm/^{\circ}C$ , respectively. In order to modify the dielectric properties and densification temperature,$B_{2}O_{3}$ and$V_{2}O_{5}$ were added to$ZnWO_4$ . 40 mol%$B_{2}O_{3}$ addition reduced the dielectric constant from 15.5 to 12. And the temperature coefficient of resonant frequency was improved from -70 to$-7.6ppm/^{\circ}C$ . However, sintering temperature did not change due to either lack of liquid phase or high viscosity of liquid phase. Incorporation of small amount of$V_{2}O_{5}$ in$ZnWO_{4}-B_{2}O_{3}$ system enhanced liquid phase sintering. 0.1 wt%$V_{2}O_{5}$ addition to the$0.6ZnWO_{4}-0.4B_{2}O_{3}$ system, reduced the sintering temperature down to$950^{\circ}C$ . Dielectric constant, quality factor, and temperature coefficient of resonant frequency were 9.5, 16737GHz, and$-21.6ppm/^{\circ}C$ , respectively. -
This study demonstrated the feasibility of tape casting method to fabricate soda borosilicate glass-coated stainless steel electrostatic chucks(ESC) for low temperature semiconductor processes. The glass coatings on the stainless steel substrates ranged from
$100{\mu}m$ to$150{\mu}m$ thick. The adhesion of the glass coatings was found to be excellent such that it was able to withstand moderate impact tests and temperature cycling to over$300^{\circ}C$ without cracking and delamination. The electrostatic clamping pressure generally followed the theoretical voltage-squared curve except at elevated temperatures and higher applied voltages when deviations were observed to occur. The deviation is due to increased leakage current at higher temperature and applied voltage as the electrical resistivity drops. -
In this paper, in-situ deposited
$Ru/RuO_2$ bottom electrodes have been investigated as new bottom electrodes for PZT thin film capacitor application. As a comparison, structural and electrical properties of PZT thin films on Pt/Ti and$RuO_2$ bottom electrodes are also investigated. The use of$Ru/RuO_2$ hybrid electrodes showed better electrical properties in compression with$RuO_2$ bottom electrode. With increasing Ru electrode thickness, the PZT thin films showed preferred orientation along the (110) direction and and leakage current of PZT thin films were improved. The PZT thin films on Ru (100nm)/$RuO_2$ electrodes exhibited excellent ferroelectric properties such as remant polarization and coercive field of$7.2C/cm^2$ and 46.35 kV/cm, respectively. -
Indium tin oxide films were deposited on unheated PET substrates by DC reactive magnetron sputtering of In-Sn (90-10 wt%) metallic alloy target. Electrical and optical properties of as-deposited films were systematically studied by control of the deposition parameters such as working pressure, DC power, and oxygen partial pressure. The figures of merit are important factors that summarize briefly the relationship between electrical and optical properties of transparent conducting films. The formulae of
$T/R_{sh}$ and$T^{10}/R_{sh}$ are expressed as a function of transmittance and sheet resistance. The best values of those figures of merit were approximately 38.6 and$8.95({\times}10^{-3}\Omega^{-1})$ respectively. -
$(Ba_{0.6-x}Sr_{0.4}Ca_{x})TiO_{3}$ (x=0.10, 0.15, 0.20) ceramics were fabricated by the mixed-oxide method and their stuctural and dielectric properties were investigated with variation of composition ratio and an amount of$Al_{2}O_{3}$ (0.5, 1.0, 1.5. 2.0, 3.0 wt%) doping content. As a result of the X-ray diffraction BSCT specimens showed dense and homogeneous structure without presence of the second phase. The sintered density was decreased with increase an$Al_{2}O_{3}$ doping content. The Curie temperature and relative dielectric constant at room temperature were decreased with increasing an amount of$Al_{2}O_{3}$ doping content. The dielectric loss is minimum for BSCT doped with 1.5wt%$Al_{2}O_{3}$ content. The tunability was decreased with increasing an Ca content and is about 4.2% for BSCT(50/40/10) doped with 2.0wt%$Al_{2}O_{3}$ content. -
The conductivity properties and synthesis of
$LaNiO_{3}$ ceramics from$La_{1+\delta}NiO_{3}(\delta=-0.06,0,0.06)$ were investigated. A single perovskite phase was realized at$800^{\circ}C$ .$La_{2}NiO_{4}$ and other unexpected oxide were observed at$1000^{\circ}C$ . The Microstructure was showed clearly that it is a low density porous material.$LaNiO_3$ ceramic showed a metallic conductivity. The conductivity of La rich samples had a higher value than the La poor samples. -
In this paper, we present results of this that design of the multi-layer VCO(Voltage Controlled Oscillator), which is composed of the resonation circuit and the oscillation circuit, using EM simulator and nonlinear RF circuit simulator. EM simulator is used for acquiring EM(Electromagnetic) characteristics of conductor pattern as well as designing multi-layer VCO, Acquired EM characteristics of the circuit pattern was used like real components at nonlinear RF circuit simulator. Finally VCO is simulated at nonlinear RF circuit simulator. The material for the circuit pattern was Ag and the dielectric was DuPont #9599, which is applied for L TCC process. The structure is constructed with 4 conducting layer. Simulated results showed that the output level was about 1[dBm], the phase noise was 102 [dBc/Hz] at 30[kHz] offset frequency, the harmonics -8dBc, and the control voltage sensitivity of 30[MHz/V] with a DC current consumption of l0[mA]
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Recently, developments of device using characteristics of ceramics as a new technical material is in progress. While doing so, Ultrasonic motor which is a part of research & development of piezo-actuator by piezo-effects is being used in the various applications. So, we fabricated a flat-type
$L_{1}-B_{8}$ mode Ultrasonic motor and measured the operation characteristics of its. The size of USM is 80*20*1.5[$mm^{3}$ ](length*width*thickness) and is constructed with stator by piezo-ceramics and stainless elastic body and rotator by bearings. As results of experiments, the fastest speed of revolution(v), the maximum torque(T) and the efficiency($\eta$ ) were 37.5[cm/sec], 5.0[$mN{\cdot}m$ ] and 1.17[%] respectively when 27.9[kHz], 150[gf], 50[V] were applied. So, we think this$flat-type_{1}-B_{8}$ mode Ultrasonic motor is able to be used for applications in forwarding device of a paper or electric card and so on. -
The ceramic filters were developed using technology similar to that of quartz crystal and electromechanical filter. However, the key to this development involved the theoretical analysis of vibration modes and material improvements of piezoelectric ceramics. The primary application of ceramic filters has been for consumer-market use. Accordingly, a major emhpasis has involved mass production technology, leading to low-priced devices. A typical ceramic filter includes monolithic resonators and capacitors packaged in unique configurations. Nakazawa developed a double-mode resonator as two acoustically coupled single resonators. And he developed 10.7MHz crystal filters using multi-energy trapping mode of thickness shear vibration. He succeeded in realizing a two-pole band pass filter response without external inductance by splitting a dot electrode to creat coupled symmetric and antisymmetric vibration modes. Accordingly, the simulation for ceramic filter were important. So that, this paper were investigated the pass frequency of filter on the electrode length and thickness of ceramic.
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The electrical properties of ZnO-
$Pr_6O_{11}$ -CoO-$Cr_2O_3-La_2O_3$ based varistors were investigated with sintering temperature in the range of$1240\sim1300^{\circ}C$ . The varistors sintered at$1240\sim1260^{\circ}C$ exhibited high density, which was 5.50-$5.70g/cm^3$ corresponding to 95.2~98.6% of theoretical density. The varistor voltage was decreased in range of 718.47~108.00 V/mm with increasing sintering temperarture. The varistors sintered at$1240\sim1260^{\circ}C$ exhibited good electrical properties, in which the nonlinear exponent is in the range of 79.25~49.22 and leakage current is in the range of 0.26~$1.00 {\mu}A$ In particular, the varistor sintered at$1240^{\circ}C$ showed very excellent electrical properties, in which the nonlinear exponent is 79.25 and leakage current is$0.26{\mu}A$