Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference (한국전기전자재료학회:학술대회논문집)
The Korean Institute of Electrical and Electronic Material Engineers
- Annual
2000.07a
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We have performed ab initio pseudopotential electronic structure calculations for various edge geometries of the (n,n) singlewall nanotube with or without applied fields. Among the systems studied, the one with the zigzag edge exposed by a slant cut is found to be the most favorable for the emission due to the existence of unpaired dangling bond states around the Fermi level. The next favorable geometry is the capped nanotube where
$\pi$ -bonding states localized at the cap and pointing to the tube axis direction occur at the Fermi level. A scaling rule of the induced field linear in the aspect ratio of the tube is also obtained. -
The population density of excited species in dc, rf and laser ablation plume plasmas has been measured using laser absorption spectroscopy. It was shown that, when the plasma was modulated by on and off with, the sensitivity and signal to noise (S/N) ratio became high. For example, the atomic O(3
$^{5}$ S$^{o}$ $_2$ ) Population density, No* in$O_2$ /He mixtures was obtained by the highest S/N ratio at a frequency of 2.7kHz. In a 20Torr room air, the lowest No* level to be detectable was shown to be an order of 10$^{7}$ cm$^{-3}$ . The population densities of resonance Ar(1S$_2$ ) and Xe(1S$_4$ ) levels were also measured in barrier discharges and laser ablation plasmas. -
A survey over the role of sol-gel processing and metal alkoxides in the thin film preparation is given. The basic chemistry of the sol-gel process is complex due to the different reactivities of the network forming and the wide variety of reaction parameters. Despite the important progress in the investigations of the mechanisms of thin film formation, a direct relation of reaction parameters to functional oxide properties is still very difficult.
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Over the years of decades, the memory technology has progressed a long, marble way. As we have evidenced from the Intel’s 1Kb DRAM in 1970 to the Gigabit era of 2000’s, the road further ahead towards the Terabit era will be unfolded. The technology once perceived inconceivable is in realization today, and similarly roadblocks as we know of today may become trivial issues for tomorrow. For the inquiring mind, the question is how the “puzzle” of tomorrow’s memory technology is pieced-in today. The process will take place both in evolutionary and revolutionary ways. Among these, note-worthy are the changes in DRAM architecture and the cell process technology. In this paper, some technical approaches will be discussed to bring these aspects into a general overview and a perspective with possibilities for the new memory technology will be presented.
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lnSb 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 20
$0^{\circ}C$ , 60 minutes. Resistance of ohmic contact increased linearly due to increasing current. Some of device fabrication technique and analysis of Hall effect were discussed. -
In this study, Transient Characteristics of the Punch-Through Insulated Gate Bipolar Transistor (PT-IGBT) has been studied. On the contraty to Non-Punch Through Insulated Gate Bipolar Transistor(NPT-IGBT), PT-IGBT has buffer layer It has a simple drive circuit controlled by the gate voltage of the MOSFET and the low on-state resistance of the bipolar junction transistor. In this paper, the transient characteristics with temperature of the PT-IGBT has been analyzed analytically. PT-IGBT is made to reduce switching power loss. Excess Minority carrier distribution inactive base region and base charge, the rate of voltage with time is expressed analytically to include buffer layer.
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In this paper, an analytical model for I-V characteristics of a HEMTs is Proposed. The developed model takes into account the temperature dependence of drain current. In high-speed ICs for optical communication systems and mobile communication systems, temperature variation affects performance; for example the gain, efficiency in analog circuits and the delay time, power consumption and noise mrgin in digital circuits. To design such a circuit taking into account the temperature dependence of the current-voltage characteristic is indispensible. This model based on the analytical relation between surface carrier density and Fermi potential including temperature dependent coefficients.
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The ~1540 nm Er
$^{3+}$ photoluminescence (PL) and photoluminescence excitation (PLE) spectra of Er-implanted Mg-codoped GaN (GaN:Er+Mg) exhibit that the excitation efficiency of a specific Er$^{3+}$ center among different Er$^{3+}$ centers existing in Er-implanted GaN is selectively enhanced, compared to Er-implanted undoped GaN (GaN:Er). In GaN:Er+Mg, the 1540 nm PL peaks characteristic of the so-called "violet-pumped" Er$^{3+}$ center and the ~2.8-3.4 eV (violet) PLE band are significantly strengthened by the Mg-doping. The intra-f absorption PLE bands associated with this "violet-pumped" center are also enhanced by this doping. The 1540 nm PL peaks originating from the violet-pumped center dominate the above-gap-excited Er$^{3+}$ PL spectrum of GaN:Er+Mg, whereas it was unobservable under above-gap excitation in GaN:Er. All of these results indicate that Mg doping increases the efficiency of trap-mediated excitation of Er$^{3+}$ emission in Er-implanted GaN.planted GaN. -
The effect of excess Pb contents on the etching of PZT thin films and their electrical properties has been investigated. Ferroelectric PZT(53/47) thin films were prepared by the metal alkoxide-based Sol-Gel method, in which they were spin-coating on P7Ti/Si02/Si substrate using the PZT(53/47) stock solutions with various excess Pb contents. Etching of PZT film was performed using planar inductively coupled Ar/Cl
$_2$ /BCl$_3$ plasma. The etch rate of PZT film was 2450$\AA$ /min at Ar(20)/BCl$_3$ (80) gas mixing ratio and substrate temperature of 8$0^{\circ}C$ . -
In this study, (Ba, Sr)
$TiO_3$ (BST) ceramics thin films were prepared by Sol-Gel method. BST solution was made and spin-coated on Pt/$TiO_2$ /Si substrate at 4000 [rpm] for 10 seconds. Coated specimens were dried at 150[$^{\circ}C$ ] for 5 minutes. Coating process was repeated 3 times and then sintered at 750[$^{\circ}C$ ] for 30 minutes. Structure and electrical characteristics of specimen was analyzed by Fractal Process. Thickness of BST ceramics thin films are about 2800[$\AA$ ]. Dielectric constant and loss of thin films was little decreased at 1[kHz]~1[MHz]. Dielectric constant and loss to frequency were 250 and 0.02 in BST3. The property of leakage current as the relation between the current and the voltage was that change of the leakage current was stable when the applied voltage was 0~3[V]. -
This paper investigated structural and electrical properties of
$Y_2$ $O_3$ as a buffer layer of single transistor FRAM (ferroelectric RAM).$Y_2$ $O_3$ buffer layers were deposited at a low substrate temperature below 40$0^{\circ}C$ and then RTA (rapid thermal anneal) treated. Investigated parameters are substrate temperature,$O_2$ partial pressure, post-annealing temperature, and suppression of interfacial$SiO_2$ layer generation. For a well-fabricated sample, we achieved that leakage current density ($J_{leak}$ ) in the order of 10$^{-7}$ A/$\textrm{cm}^2$ , breakdown electric field ($E_{br}$ ) about 2 MV/cm for$Y_2$ $O_3$ film. Capacitance versus voltage analysis illustrated dielectric constants of 7.47. We successfully achieved an interface state density of$Y_2$ $O_3$ /Si as low as 8.72x1010 c$m^{-2}$ e$V^{-1}$ . The low interface states were obtained from very low lattice mismatch less than 1.75%. -
In this paper,
$Ba_{0.5}$ Sr$_{0.5}$ TiO$_3$ thin films were prepared on Pt/Ti/SiO$_2$ /Si substrate by RF magnetron sputtering method. We investigated effect of deposition conditions (especially RF input power) on structural properties of BST thin films. Deposit conditions of BST films were set working gas ratio, Ar:O$_2$ = 70 : 30, working pressure 10mTorr, and RF input power 25W, 50W, 75W and 100W. Post-annealing using rapid thermal annealing(RTA) performed at 45$0^{\circ}C$ , 55$0^{\circ}C$ ,$650^{\circ}C$ , and 75$0^{\circ}C$ in oxigen ambient for 60 sec, respectively. The structural properties of BST films on Pt/Ti/SiO$_2$ /Si substrate analysed by X-ray diffraction(XRD).).). -
SiGe heterojuction bipolar transistors (HBT) have been studied and applied for advanced high speed integrated circuits. Device characteristics of SiGe HBT depending on the Ge profile of the transistor base region have been analysed using a device simulator, ATLAS/BLAZE. The models and parameters have been calibrated to the measured characteristics of the device, having a trapeziodal base profile, including the cut-off frequency of 45GHz and the dc current gain of 200. The Ge concentration which increases linearly, exponentially, or root-functionally from the emitter-base junction to the base-collector junction, has been tried to find out the influence on the device characteristics. The cut-off frequency and gain rather strongly depends on the exponential and root-functional Ge base profiles, respectively.
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A VLSI implementation of a self-learning neural network integrated circuits using a linearity synapse transistor is investigated. The thickness dependence of oxide current density, stress current, transient current and channel current has been measured in oxides with thicknesses between 41 and 112
$\AA$ , which have the channel width$\times$ length 10$\times$ 1${\mu}{\textrm}{m}$ respectively. The transient current will affect data retention in synapse transistors and the stress current is used to estimate to fundamental limitations on oxide thicknesses. The synapse transistor has represented the neural states and the manipulation which gave 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 drain source current. -
In this paper, we present the simulation of the heterojunction bipolar transistor with different Emitter-Base junction structures. Our simulation results include effect of setback and graded layer. We prove the emitter efficiency's improvement through setback and graded layer. In 1995, the analytical equations of electric field, electrostatic potential, and junction capacitance for abrupt and linearly graded heterojunctions with or without a setback layer was derived. But setback layer and linearly graded layer's recombination current was considered numerically. Later, recombination current model included setback layer and graded layer will be proposed. New recombination current model also wile include abrupt heterojunction's recombination current model. In this paper, the material parameters of the heterojunction bipolar transistor with different Emitter-Base junction structures is introduced.
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In this paper, all SCR recombination currents including setback and graded layer's recombination currents are analytically introduced for the first time. Different emitter-base structures are tested to prove the validity of the model. In 1995, the analytical equations of electric field, electrostatic potential, and junction capacitance for abrupt and linearly graded heterojunctions with or without a setback layer was derived. But setback layer and linearly graded layer's recombination current was considered numerically. In this paper, recombination current model included setback layer and graded layer is proposed. New recombination current model also includes abrupt heterojunction's recombination current model. In this paper, new recombination current model analytically explains effects of setback layer and graded layer.
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Pt/Pb
$TiO_3$ /$SrTiO_3$ /p-Si films were prepared by metallo-organic solution deposition(M0SD) method and investigated its structure and ferroelectric properties. Crystallinity of specimen as a funtions of post annealing temperature and the thickness of$SrTiO_3$ (STO) buffer layer was studied using XRD and AFM. Based on C-V and P-E curve,$PbTiO_3$ (PTO) capacitors showed good ferroelectric hysteresis arising from the polarization switching properties. When the thickness of ST0 buffer layer between PTO and Si substrate was 260 nrn and the post annealing temperature was$650^{\circ}C$ , it was showed that production of the pyrochlore phase due to interdiffusion of Si into FTO was prevented. The dielectric constant of FTO thin films calculated from a maximum Cma in the accumulation region was 180 and the dielectric loss was 0.30 at 100 kHz frequency. The memory window in the C-V curve is 1.6V at a gate voltage of 5V. -
This paper is estimated to enhance yield improvement and device reliability using PDM(plasma damage monitoring) system capable of in-suit detection about plasma nonuniformity. PDM Tool is the non-contact method of wafer and surface potential electrode(kelvin probe). Its tool measures Vox(oxide barrier) with charge created by plasma. It's possible to inspect the wafer damage generated by plasma charge and analysis of in-situ monitoring data. we obtained the good data which is continuously prevented from plasma damage using its tool for 10weeks. This tool is contributed to preventive steps contemporaneously inspecting the difference of inter-chamber.
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Outdoor insulation of overhead distribution lines with wood, concrete and steel pole has been safety under various environmental conditions including contamination, moisture condensation, rain and lightning overvoltages. In this paper introduce to FRP technology of the power distribution single pole. FRP pole has been used very much as high strength material for insulators because of its high strength and good insulation properties. In addition, FRP pole was made by filament winding method. In a filament winding process, a band of continuous resin-impregnated rovings or monofilaments is wrapped around a rotating mandrel and cured to produce axisymmetric hollow parts.
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The less sensitive structure to the surface effect has been presented utiliting an undoped GaAs layer on the n-GaAs channel. The undoped layer has been found to be effective to supress the frequency dispersion phenomena caused by a surface trapping effect and to raise the MESFET's performance. The gate structure, with an undoped layer underneath the gate metal has been found to be effective to improve the breakdown voltage. GaAs MESFETS with different physical structures are fabricated and DC characteristics are measued. GaAs MESFET's are fabricated on epi-wafers which have an undoped GaAs layer in between n+ and n GaAs layers grown by MBE.
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The detection technique both the polarization and the mobile charge density at the same time in ferroelectric films on Si using TVS method have been proposed. This method yields a polarizable and an ionic displacement current peaks whose areas are proportional to the total polarization reversal charge and the total moble ionic space charge, respectively. The calculated polarization and the mobile charge density were 0.42 [
$\mu$ C/$\textrm{cm}^2$ ] and 5.5$\times$ 10$^{11}$ (ions/$\textrm{cm}^2$ ) in the SBT film of MFIS structure measured at 25$0^{\circ}C$ , and 1.4 [$\mu$ C/$\textrm{cm}^2$ ] in the LiNbO$_3$ film of MFS structure measured at 30$0^{\circ}C$ , respectively. -
In this study, the rise throughput and the stability in fabrication of device can be obtained by applying of CMP process to STI structure in 0.18um semiconductor device. To employ in STI CMP, the reverse moat process has been added thus the process became complex and the defects were seriously increased. Removal rates of each thin films in STI CMP was not equal hence the devices must to be effected, that is, the damage was occured in the device dimension in the case of excessive CMP process and the nitride film was remained on the device dimension in the case of insufficient CMP process than these defects affect the device characteristics. To resolve these problems, the development of slurry for CMP with high removal rate and high selectivity between each thin films was studied then it can be prevent the reasons of many defects by reasons of many defects by simplification of process that directly apply CMP process to STI structure without the reverse moat pattern process.
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Polycrystalline SBTN ferroelectric thin films were prepared by sol-gel method with various Nb mole ratios on Pt/
$SiO_2$ /Si (100) substrates. The films were annealed at different temperatures and characterized in terms of phase and microstructure. Relatively a well saturated hysteresis pattern was obtained at x =0.2 in S$r_{0.8}$ B$i_{2.3}$ (T$a_{1-x}$ N$b_{x}$ )$_2$ $O_{9+}$ $\alpha$ / thin films. At an applied voltage of 5V, the dielectric constant ($\varepsilon$ $_{r}$ ) and dissipation factor (tan$\delta$ ) of typical S$r_{0.8}$ B$i_{2.3}$ (T$a_{1-x}$ N$b_{x}$ )$_2$ $O_{9+}$ $\alpha$ / thin film (x=0.2) were about 236.2 and 0.034. Measured remanent polarization (2Pr) and coercive field (Ec) were 4.28C/c$m_2$ , and 38.88kv/cm respectively. No fatigue was observed up to 6$\times$ 10$_{10}$ switching cycles at 5V and the normalized polarization reduced by a factor of only 4%.%. 4%.%. 4%.%.%.%.%. -
Via for achieving reliable fabrication of MCM-D substrate was formed on the photosensitive BCB layer. MCM-D substrate consists of photosensitive BCB(Benzocyclobutene) interlayer dielectric and copper conductors. In order to form the vias in photosensitive BCB layer, the process of BCB and plasme etch using
$C_2$ F$_{6}$ gas were evaluated. The thickness of BCB after soft bake was shrunk down to 60% of the original. AES analysis was done on two vias, one is etched in$C_2$ F$_{6}$ gas and the other is non etched. On via etched in$C_2$ F$_{6}$ , native C was detected and the amount of native C was reduced after Ar sputter. On via non etched in$C_2$ F$_{6}$ , organic C was detected and amount of organic C was reduced a little after Ar sputter. As a result of AES, BCB residue was not removed by Ar sputter, so plasma etch is necessary for achieving reliable via.ble via. -
Boron Phosphide films were deposited on the glass substrate at the low temperature, 55
$0^{\circ}C$ , by the reaction of B$_2$ H$_{6}$ with PH$_3$ using CVD.$N_2$ was employed as carrier gas. The optimal gas rates were 50$m\ell$ /min for B$_2$ H$_{6}$ , 50$m\ell$ /min for PH$_3$ $m\ell$ /min and 1.5$\ell$ /min for$N_2$ . To investigate the annealing effect, the films were annealed for 1hour, 3hours in$N_2$ ambient at 55$0^{\circ}C$ and tested. The deposition rate was 1000$\AA$ /min and the refractive index of film was 2.6. The measurement of X-RD shows that the films have the preferred orientation of (1 0 1) and the intensity of the peak for (1 0 1) orientation decreases according to the annealing time. The data of VIS spectrophotometer proved that the films are transparent in the visible range and the maximal transmittance increases according to the annealing time; 75.49% for as-deposited, 76.71% for 1hr-annealed and 86.4 % for 3hrs-annealed. The measurement of AFM shows that the average surface roughness increases according to the annealing time; 73$\AA$ for as-deposited, 88.9$\AA$ for 1hr-annealed and 220$\AA$ for 3hrs-annealed. Also, The data of the secondary electron emission rate(Υ) shows that the secondary electron emission rate increases according to the annealing time; 0.317 for 1hr-deposited, 0.357 for 1hr-annealed and 0.537 for 3hrs-annealed. And, The measurement of FT-IR that the characteristic of transmittance in the infrared range was stabilized through annealing.ing. -
The aim of this paper is to investigate the effect of Al and Ti on microstructure of Fe-Cr-Al alloy systems for applying electrical resistance wires of electrical furnace. From the preliminary study, the amount of recovered addition elements increased in the case of both vacuum and Ar-atmosphere melting than that in the case of air-atmosphere melting. Also, optimum Cr content for good performance at high temperature was approximately 24wt% from the observation of microstucture. The precipitates of Fe-Cr, Al-Cr and Al phases were observed, adding Al and Ti. Especially, Sharp rectangular shapes of precipitates were observed with increasing amount of Ti.
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Growth characteristics and microstructure of AlN thin films grown by plasma assisted molecular beam epitaxy on Si substrates have been investigated. Growing temperature and substrate orientation were chosen as major variables of the experiment. Reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy/diffraction (TEM/TED) techniques were employed to characterize the microstructure of the films. On Si(100) substrates, AlN thin films were grown along the hexagonal c-axis preferred orientation at temperature range 850-90
$0^{\circ}C$ . However on Si(111), the AlN films were epitaxially grown with directional coherency in AlN(0001)/Si(111), AlN(1100)/Si(110), and AlN(1120)/Si(112) at 85$0^{\circ}C$ and the epitaxial coherencry seemed to be slightly distorted with increasing temperature. The microstructure of AlN thin films on Si(111) substrates showed that the films include a lot of crystal defects and there exist micro-gaps among the columns. -
In case of developing new motor, many examinations was tested to decide a motor efficiency and reliability. To give reliability judgment, traction motor winding insulation was tested by electrical method after appling electrical, heat, mechanical, environmental stress. In this study, stator form-wound winding of traction motor in urban transit E.M.U was tested by accelerative thermal degradation test. Stator form-wound winding was tested on the accelerative degradation composed of heat, vibration, moisture, overvoltage and researched insulation resistance, dielectric loss, partial discharge for insulation degradation properties, evaluated withstand voltage. Degradation temperature was
$230[^\circ{C}]$ , $250[^\circ{C}]$ , $270[^\circ{C}]$ , for stator form-wound winding respectively. On the test results of accelerative thermal degradation, insulation properties were relied all temperature until 10 times and expected life was evaluated by the rule of reducing $10[^\circ{C}]$ life into halves. Expected life was 31.8 years. It is guaranteed insulation reliability because of exceeding 25 years life times as considering. -
Recently polymer insulators are being used for outdoor high voltage applications. Polymer insulators for transmission line have significant advantages over porcelain and glass insulators, especially for ultra-high voltage transmission lines. Their advantages are light weight, vandalism resistance and hydrophobicity. Polymer insulators are a relatively new technology, but their expected life is still unknown. Therefore these estimating technique are very important. Their life time is related to weathering and operating condition. Multi-aging test is requested because aging factor is occurred by multi-aging than unique aging. The aging test about polymer insulators have mainly carried out by IEC 61109. This paper presents multi-stress chamber experiments and tracking wheel test to examine the tracking and erosion performance of polymer insulator for transmission. Multi-stress testing is able to demonstrate deficiencies of polymer insulator materials and designs, including the nature of interfaces in insulation design. We have investigated IEC 61109 Annex C (5000h aging test) and CEA tracking wheel test as test methods of artificial accelerated aging. The aging degree of polymer insulator is estimated by leakage current, measurement of hydrophobicity degree, damage conditions of insulator surface, withstand voltage test etc.
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In order to investigate the influence of manufacturing process on the electrical properties, we used two kinds of low density polyethylene prepared using metallocene catalyst (mL), linear low density polyethylene prepared using Ziegler catalyst (LL) and low density polyethylene by high pressure process (LD). mL has the narrowest composition and molecular weight distributions. We measured the dc and impulse breakdown strengths and current densities at 3
$0^{\circ}C$ , 6$0^{\circ}C$ and 9$0^{\circ}C$ . mL had a higher breakdown strength and a lower high-field current than LD and LL. These results were discussed from the point of manufacturing processes. -
Performance Evaluation and Housing Design for Direct Current Surge Arrester in Railway Rolling StockThe main objective of this paper is to design and test a new type of polymer ZnO surge arrester for DC power system of railroad vehicles. The rated voltage is 1500V direct current. The main research works are focused on structure design by finite element method, rating voltage, temporary over voltage and studies of characteristics of polymeric surge arrester.
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This paper present the results of measured Thermally Stimulated Current of EPR(Ethylene Propylene Rubber) sheet material with variation of bias temperature range of -35~80[
$^{\circ}C$ ], the quality of the material of electrode, condition. The origins of these peaks are that, low temperature peak seems to result from dipole, and high temperature peak from the orientation electronic trap. -
Epoxy materials are used as insulation material for electric power cables. In the case of a flow of excess current due to the temperature difference which occurs between the heat of the conductor and the atmosphere, heat degrades connection point of the cables. Also, the mechanical stress, which occurs due to the thermal expansion coefficient of cable connection electrode system and epoxy insulation materials along with the gap between thermal conduction based on the extra high voltage of transmitted voltage, increases possibility of cracks to occur. The relationship between mechanical stress and electrical breakdown mechanism is verified for the epoxy materials such as high toughness epoxy materials, which comes to be used contemporarily, and for the breakdown mechanism of epoxy materials on the multi-stresses (mechanical and electrical) due to the variation of the temperature.
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The primary function of ZnO lightning arrester is to protect transmission and distribution equipment from overvoltages and to absorb electrical energy resulting from lightning or switching surges and form temporary overvoltage. However, ZnO lightning arrester are known to exhibit an increases in resistive current with time, the rate of increase being exacerbated with increasing applied voltage and ambient temperature. So, it is important to the leakage current measurement of ZnO lightning arrester. In addition, since the resistive leakage current caused by deterioration of ZnO lightning arrester mainly caused an increase of the third harmonic component, thereby it is possible the arrester degradation diagnosis by measuring the third harmonic component in the total leakage current. The leakage current and third harmonic component are measured and used to investigate the degradation diagnosis of ZnO element of arrester. Also the SEM photography is used to investigate the change of crystal structure of ZnO element with degradation.
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The effect of accelerated aging test on ethylene-propylene-diene monomer(EPDM) rubber used for outdoor insulation was studied by X-ray photoelectron spectroscopy(XPS), scanning electron microscope(SEM), FFT spectrum alalysis, and electrical pulse counts using PC by oscilloscope(300 MHz). In electrical alalysis, FFT spectrum analysis indicated arcing caused a significant increase in the third harmonic content of the leakage current of polluted insulator. Also, pulse counts increased as aging time. The surface oxygen and aluminum content were found to increase and that of carbon and nitrogen were found to decrease with time. The detailed XPS analysis indicated that the concentration of carbon in C-C decreased and concentration of highly oxidized carbons increased with time, which was due to the oxidation of EPDM rubber polymer SEM analysis indicated that crack and erosion of EPDM rubber occurred with time.
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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 temperature range of 20[
$^{\circ}C$ ]~150[$^{\circ}C$ ] about frequency 30[Hz], 1[kHZ] and 30[kHz] respectively from a series of experiments. Consequently, observed higher values of dielectric permittivity and loss in filled epoxy are attributed to Maxwell-Wagner Polarization effect. Also, glass transition temperature was shifted to higher temperature and value of dielectric permittivity and loss were decreased due to 2nd curing. -
PWM inverter-fed traction motor is able to occur problems by additive transient surge stress and harmonic loss in contrast with motor driven by 60Hz sine wave alternating source. Therefore in this paper, test method and standard of existed already were investigate, "thermal + electric" complex degradation test that considered additive degradation occurred by inverter drive carried out in order to obtain insulation reliability of traction motor driven by inverter. It seems that this test method confers large value of application at reliability estimation which the subject of complete motor not windings sample from now on.
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In this paper, the physical and electrical properties of epoxy composites are investigated at boiling absorption condition to observe the influences of moisture. Also, in order to improve water resistance of matrix resin, IPN method was introduced and the influence was investigated. In order to analyze the basic physical properties of samples, scanning electron microscopy method was utilized, and impulse voltage dielectric strength was measured. As a result, it was verified that, in case of IPN samples, the ratio of moisture absorption was decreased due to the improvement of adhesion strength, and impulse voltage dielectric strength of SN sample was degraded abruptly as boiling time and filler content were increasing, while IPN samples were slowly degraded due to the improvement of adhesion strength.
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This paper describes oil water separator using difference of electrical resistor. Oil is a non-conductive element and water is a relatively high conductive element. It is possible to detect water included in oil. Electric sensor is formed 8mm iron stick. Valve is operated With controller inputting signal of electric sensor. A experiment was done for necessary voltage in making program of controller. Oil water separator which was tested in field conditions was saved 7% of whole oil and was drained over 150% water than manual valve.
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This paper presents the tracking resistance and mechanical strength due to boiling absorption of epoxy resin. The single network structure specimen(E series) formed of epoxy alone and interpenetrating polymer network(IPN) structure specimen(EM series) which epoxy resin was taken as first network and methacrylic acid resin as second network were manufactured. As adding
$SiO^2$ filler classified by o[phr], 50[phr] and 100[phr] to those specimens, six kinds of specimens were manufactured and boiled in water during 2, 4, 8, 16, 32 and 64[hours]. As a result, it was confirmed that the tracking breakdown time of E series showed a abrupt decrease with boiling time increasing, but that of EM series was decreasing smoothly. Also, it was verified that the degrading rates of mechanical strength was lowerd according to improvement of adhension strength in case of EM series. -
In this paper, we evaluated the mechanical and dielectric properties of LDPE depend on
$Co_{60}$ ${\gamma}$ -irradiation doses. The chemical analyses for FT-IR, gel content, the mechanical properties for elongation at break and the dielectric parameters for permittivity, tan$\delta$ were discussed as a function of irradiation doses. Test result presented that elongation at break of irradiated LDPE was inversely proportional to gel content. For dielectric analyses, permittivity showed a salient characteristic for various irradiation doses, it was related to polar groups caused radiation degradation and tan$\delta$ of irradiated LDPE increased with irradiation doses. -
In this paper, we investigated the surface degradation of HTV silicone rubber used for a polymeric insulator by UV irradiation. To study the surface ageing properties by W irradiation, we used the corona discharge charging and contact angle. Therefore, we observed the change of surface charge retention and decrease of surface hydrophobicity. Also, we discussed the chemical change in the surface range using the analytic equipment such as SEM, ATR-FTIR, ESCA. Therefore, it is found that the scissor of characteristic bonding and the reattachment of oxidant bonding was developed by UV rays radiation. As discussing the corona ischarge charging and the change of contact angle, it is found the effect of UV irradiation and the mechanism of chemical reaction
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We studied the degradation of EVA for the protection of solar cell by UV-rays irradiation. We investigated the reduction of electrical efficiency, photo transmmitance and degradation of EVA by UV-rays irradiation. We utilized the UV irradiation equiped with fluorescent 313nm UV lamp and radiated for 400 hours. For the chemial analysis, we used the UV-vis spectrometer, XPS and examined the degradation mechanism by UV irradiation. It is found that the discolored phenomena, the decrease of photo transmmitance and oxidation reaction is occured by UV irradiation on the EVA sample for the protection of solar cell.
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LDPE pelet is distilled to make 0.5 Wt% solutions and fabricated as LDPE thin film by dropping the solution onto glass substrate, and then annealed the film to be crystalline. The structure is observed as crystalline regions and non-crystalline regions. The crystalline region is exposed at radiation and as the result, there appeared degradation at the total region of the crystal structure. It is considered therefore that radiation exposure at the crystal structure is badly effected on insulation property and lifetime of materials.
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Crystal orientation of Ni
$_{18}$ $Fe_{19}$ thin films prepared by facing targets sputtering system was investigated. FTS system can deposit a high quality thin film and control deposition conditions in wide range. T he crystallographic characteristics of Ni$_{18}$ $Fe_{19}$ thin films on variation of thickness and substrate tempera ture was investigated by XRD and AFM. As a result, we obtained Ni$_{18}$ $Fe_{19}$ thin films prepared at subst rate temperature room temperature, thickness 160nm and over revealed good crystal orientation to [111] direction.irection. -
High-temperature superconductor of Bi-2212 system was fabricated by CFP(centrifugal forming process). To make a uniform specimen slurry was prepared in the ratio of 7:3(powder:binder) and ball milled for 24 hours. Milled slurry was charged into a rotating mold with 450 rpm and dried at room temperature. Then the specimen was performed binder burn-out at 35
$0^{\circ}C$ and heated for partial melting to 86$0^{\circ}C$ . XRD analysis of most specimens were shown 2212 phase and observed a local plate shaped microstructure with a well aligned c-axis direction from SEM images. T$_{c}$ (Critical temperature) of Bi-2212 was 64K.K. -
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 73
$0^{\circ}C$ and decreases linearly with temperature over 73$0^{\circ}C$ . 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. -
This paper investigated the effects of doping elements on the Bi-Sr-Ca-Cu-O ceramics. The doping elements can be classified into four groups depending on their superconducting characteristics in the Bi-Sr-Ca-Cu-O structure. The first group of doping elements(Co, Fe, Ni and Zn) substitute into the copper site and can reduce the critical temperatures of the 2223 and 2212 phases. The second group of doping elements(Y and La) substitute into the Ca site and cause the disappearance of the 2223 phase and increase the critical temperatures in the 2212 phase. The third group of doping elements(P and K) have a tendency to decompose the superconducting phase and reduce the optimal sintering temperature. The fourth group of doping elements(B, Si, Sn and Ba) almost unaffected the superconductivity of the 2223 and 2212 phase.
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In this paper, we have studied the effect of doped with B-Bi-Zn on properties (microstructure, density, shrinkage, permeability as a function of frequency, etc.) of hexagonal-ferrite for high frequency chip-inductor material about several GHz. The permeability were analyzed by impedance analyzer(100 kHz~40 MHz) and network analyzer(30 MHz~3 GHZ). As a result of the characteristics, the B-Bi-Zn glass ceramic was used to lower the sintering temperature for additive as a function of frequency from 100 kHz to 1.8 GHz showed constant tends. The maximum imaginary value of complex permeability was observed near the resonance frequency of 2 GHz.
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We prepared Co-Cr-Ta and Co-Cr-Ta/Ti thin film for perpendicular magnetic recording media by facing targets sputtering system (FTS system). Ti underlayer effects on crystallographic and magnetic characteristics of Co-Cr-Ta perpendicular magnetic recording media have been investigated. Crystallgraphic and magnetic characteristic of prepared thin films were evaluated by x-ray diffractometry(XRD), vibrating sample magnetometer(VSM) and kerr hysteresis loop measurement. The coercivity and anisotropy field increase by introduced Ti underlayer when substrate temperature is higher than 150
$^{\circ}C$ . The c-axis dispersion angle and grain size of Co-Cr-Ta/Ti thin film is decrease than Co-Cr-Ta when substrate temperature is higher than 100$^{\circ}C$ . Consequently, the use of a Ti underlayer highly orientated can be improved crystallographic and magnetic characteristics of Co-Cr -Ta perpendicular media layer. -
Bi
$_2$ Sr$_2$ CuO$_{x}$ (Bi-2201) thin films have been fabricated by atomic layer-by-layer deposition using ion beam sputtering(IBS) process. During the deposition, 14 wt%-ozone/oxygen mixture gas of typical pressure of 5.0$\times$ 10$^{-5}$ Torr is supplied with ultraviolet light irradiation for oxidation. XRD and RHEED investigations reveal that a buffer layer with compositions different from Bi-2201 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. -
Currently, Bi-2223 HTS tape is capable of being fabricated in longer than 100m length by industrial processes. But there are some problems in heat treatment of the degree of longer than 100m tape, which is in term of volume occupied with specimen in furnace. The effects of ceramic coating with variable slurry states were studied in Bi-2223 high-temperature superconductor. The HTS tapes coated with oxide were prepared by using dip-coating method on slurry state. Critical current(I
$_{c}$ ) of tapes coated with ceramic materials were equal with 11.5A at 77K after first heat treatment as different slurries. For final heat treatment, Critical current of HTS tapes coated with zirconia oxide mixed in PMMA and PVA organic solute were 20.8A at 77K. The breakdown voltage of HTS tapes coated with zirconia oxide were 3kV in air and 4~7kV in L$N_2$ .>. -
BSCCO thin films have been fabricated by co-deposition at an ultralow growth rate using ion beam sputtering(IBS) method. 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 smd amount of CuO in some films was observed as impurity, and no impurity phase such as$CaCuO_2$ was observed in d of the obtained films. -
We fabricated thin film superconducting fault current limiters based on YBa
$_2$ Cu$_3$ O$_{7}$ thin films and investigated the distribution of quench progress in the limiters. The limiters were tested with simulated fault currents. Quench progress depended significantly on the position in the limiter with respect to electrodes as well as the fault current magnitude. The heat transfer from limiter meander lines to electrodes explains these results.s. -
Bi
$_2$ Sr$_2$ Ca$_{n}$ Cu$_{n+1}$ O$_{y}$ (n$\geq$ 0; BSCCO)thin film is fabricated via two different processes using an ion beam sputtering method i.e. co-deposition and layer-by-layer deposition. A single phase of Bi2212 can be fabricated via the co-deposition process. While it cannot be obtained by the layer-by-layer process. Ultra-law growth rate in our ion beam sputtering system brings out the difference in Bi element adsorption between the two processes and results in only 30% adsorption against total incident Bi amount by layer-by-layer deposition, in contrast to enough Bi adsorption by co-deposition.on.n. -
There have been a lot of studies to improve the characteristic of Bi-2223 tape by PIT method which is considered as one of the best way for applying superconductor. These improved characteristic of Bi-2223 tape is able to be acqured by control of mechanical deformation and heat treatment. In this work, we studied HTS tapes with the sheath(Ag and Ag-alloy)of tapes that affect mechenical strength and critical current, with each two kind of purity(99.9% and 99.999%) and with two kind of tapes(single and double concentric). These charateristics affect Jc of tapes seriously that is the most important factor of superconductor tapes.
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To fabricate YBa
$_2$ Cu$_3$ O$_{x}$ thick film using diffusion process,$Y_2$ BaCuO$_{5}$ and BaO+CuO as the material of substrate and the doping material were selected. CeO$_2$ in the doping material was mixed. As another doping material, YBa$_2$ Cu$_3$ O$_{x}$ was prepared for the comparison with BaO+CuO doping material. Each doping material was patterned on$Y_2$ BaCuO$_{5}$ substrate by the screen printing method and then was annealed above peritectic reaction temperature of YBCO with a few step. It could be observed by X-ray diffraction patterns and SEM photographs that through the diffusion process of the$Y_2$ BaCuO$_{5}$ and BaO+CuO, the YBa$_2$ Cu$_3$ O$_{x}$ phase was formed. With an amout of addition of CeO$_2$ , the thickness of a formed YBa$_2$ Cu$_3$ O$_{x}$ decreased. x/ decreased. -
The sputtering systems mainly consist of the three-target holder. The target and substrate were the on-axis type. The MgO and STO substrate were used for the deposition of each layer. The optimum conditions of single-layer thin film were investigated from the SEM images and the XRD patterns. Based on the above conditions, the multi-layer thin films such as YBaCuO/LaGaO/Au/Nb and YBaCuO/Au/Nb were fabricated. The crystalline, the electrical Properties, the energy gap structure and the characteristics of the tunneling barrier on the multi-layer thin film have been investigated and characterized.
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본 연구에서는 double rectangular spiral형 공심 인덕터를 제조하고, 인덕터 특성에 미치는 자성막의 특성 인자에 대해 연구하였다 공심 인덕터의 전류의 방향과 자성 박막의 자화 용이축의 방향이 수직일 경우 인덕터의 인덕턴스가 향상되었고, 도체막과 자성막 사이 절연막이 없는 경우 자성막의 자속 집속효과가 증가하여 절연막이 있는 경우보다 인덕턴스는 높고, 저항의 증가율이 높았으며, 자성막의 투자율이 높을수록 인덕터의 인덕턴스에 기여하는 부분이 증가하므로 인덕턴스는 향상되었다. 또한 인덕터의 주파수 특성은 공심 인덕터의 특성에 지배적인 영향을 받으므로 인덕터의 주파수 특성을 향상시키기 위해서는 자성막의 특성보다 공심 인덕터의 특성을 향상시키는 것이 바람직하다
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High temperature superconducting films deposited on metal Ag wire were prepared with YBCO powders by electrophoretic deposition method.
$I_2$ was used as additives for surface charge of YBCO particles. When 2~3 wt.%$BaF_2$ was added in the YBCO suspension, the pores and cracks of film surface were decreased and film density could be increased. In case of YBCO films, the critical current density ($J_{c}$ ) was calculated at the value of$1458{\;}A/\textrm{cm}^2$ (77K, 0K) by 4 point prove method. -
The new approach for synthesis of novel condensation monomers and polyimides on the basis of them was developed. The correlation between synthesis regularities, structure and properties of monomers and polyimides was studied. The areas of industrial application of synthesized polymer were determined.
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Systematic research of metal alkoxide electrophoretic deposition has been developed. The formation mechanism of electrophoretic deposits has been offered. The structure study of dry and heat-treated electrophoretic deposits has been established. The concrete examples of one and bi-component oxide thin film formation were considered. The new approaches for thin film technology have developed on various substrates of different shapes and sizes. The correlation between thin film structure, mechanism of their formation, and physico-chemical properties has been determined.
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Nowadays the hydrophilic polymeric networks (polymer hydrogels) due to the complex of benefit physico-chemical properties attract a wide attention of specialists working in various fields of science, medicine and technology. The special attention of chemists is aimed on so-called stimuli-sensitive or intelligent hydrogels, which can undergo a volume phase transition in response to change in environmental parameters such as temperature, pH, solvent composition, etc [1]. Scientific group of Kazak State National University, Department of Macromolecular Chemistry works in this field [2-5]. Here we report about our achievements on pH-sensitive hydrogens.
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For the well-preparation of the superconducting wire by electrophoresis, the control of the cracking on the YBCO, BSCCO superconductor deposited on Ag wire in acetone and buthanol solution with PEG(poly-ethylenglycol) was investigated with XRD and SEM analysis. After deposition, drying and heat treatment process, the cracks on the deposited surface of YBCO and BSCCO samples was clearly removed and decreased, which was perpared in suspension with addition of PEG from 1 to 3ml. However, in the case of the addition rate of PEG in acetone suspension was exceeded in 3ml, BSCCO superconductor deposited on Ag wire was slightly melted at 90
$0^{\circ}C$ which was the same heat treatment condition of other samples with different additin rate of PEG. In the process of electrophoretic deposition, drying and heat treatment, PEG added into the suspension solution as a binder was very useful to prepare the crack-free thick film-wire of YBCO and BSCCO. -
SHS is recognized as an attractive process for producing high-temperature, hard materials that difficult and/or expensive to produce by conventional fabrication methods. The goal of this work is to investigate new express technology of doped Fe alloys materials. The high density, homogeneity of the components, and the low processing temperatures achieved and minimum synthesis time are all of paramount importance in fabricating Fe alloys as functional materials.
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The activity of catalysts obtained by self-propagating high temperature synthesis in reaction of partial methane oxidation at atmospheric pressure was investigated. Basing on the compared results of X-ray analysis and gas chromatography analysis of reaction products, the dependence of compounds formation on the phase concentrations in the studied catalyst samples was found.
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We analyzed the 3-dimensional discharge characteristic in plasma display panel(PDP) cell using the 3-dimensional emission distribution of 828nm light measured by scanned point detecting method(SPDM). The emitted light distributions on the ITO electrode show the stronger light intensity near to the electrode gap than outside. Also, 828nm light is widely detected outside of the bus electrode. We consider that measurement using new SPDM is effective to analyze the discharge physics and propose the new panel structures.
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BPM simulation was used in order to fabricate the LiNbO
$_3$ optical waveguide with optical source of He-Ne laser(λ=0.6328[$\mu$ m]). we observed electric field E$_{x}$ , E$_{y}$ in the x,y-direction are simulated at the LiNbO$_3$ substrate (X1 55[$\mu$ m]$\times$ Z1 5000[$\mu$ m]), where the depth, width and buffer layer of waveguide are 0.2[$\mu$ m],4[$\mu$ m] and 0.02[$\mu$ m] respectively. By applying these parameters of single waveguide to simulate a X-switch, we have chosen index change of 0.002, width of 3[$\mu$ m] and angle of 0.4$^{\circ}$ ~0.6$^{\circ}$ of optical waveguide and under these conditions, optical beam propagates cross-side at 0.4$^{\circ}$ . When applied switching voltage of 25[V], optical beam of X-switch turns cross-side to bar-side at intersection angle 0.4$^{\circ}$ , index change of 0.002, waveguide width of 3[$\mu$ m], electrode gap 2[$\mu$ m]. By the above results, we can obtain design conditions of theoretical analysis of an X-switch optical waveguide.e.e. -
As the LED or LCD technology has been developed, if we use LED or LCD pannel, more wide color range coluld be obtained as CRT monitor. Specially, full color LED display is developed by high brightness blue LED. It can be applicable to display pannel with a long-life, wide visible angle and high brightness. A display pannel shows the images of CRT monitor performed by the main computer. Graphic application in the main computer is therefore more important in the market. Conventional 3D STUDIO, one of graphic softwares, has difficulties in manipulating and understanding the specific terminology so that one may need more time to learn it. We, therefore, developed graphic application which can recycle the conventional 3D images by creating or editing the image easily.
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In this study, we have made the large holographic surface relief gratings on amorphous chalcogenide
$As_{40}$ $Ge_{10}$ $Se_{15}$ $S_{35}$ films by two beam interference using a He-Ne laser(632.8nm) light. The film thickness was about 0.6$\mu\textrm{m}$ , we could magnify beam size by using beam expander. We made use$90^{\circ}$ holder which was made of reflection mirror and sample. Formed the surface relief structures were investigated using optical microscope. The diffraction efficiency was obtained by measuring +lst order intensity. In addition we investigated grating formation and diffraction efficiency as a function of polarization states which is linear or circular polarization. The results indicate that the grating was formed by linear polarized beam is better clear than that by circular polarized beam. -
The crystal structure of ZnS fabricated by gas-liquid phase reaction was obtained by XRD and refined by RIETAN near R
$_{wp}$ factor 10%. The increasement of HCP phase depended on extra H$_2$ S gas and the lattice parameter and crystalline size changed by the relative ratio of multiphase. Using ZnS of the different multiphase ratio and crystalline size, sintered ZnS:Cu, Al green phosphor and the CL property resulted optimum luminescence in the range of 91~94% and 150~190$\AA$ , respectably, FCC/HCP ratio and crystalline size. As changing of structure ratio, the reason of different luminescence property is now studying. As well as, after XRD pattern of TiO$_2$ powder fitted by RIETAN and the structure factor using MEED method simulated about each atom of (002) plane. Additionally, we proposed RIETAN and MEED were the methods of the study of luminescence mechanism for many phosphor materials.s. -
The organic electroluminescene (EL) device has gathered much interested because of its potential in materials and simple device fabrication. We fabricated EL device which have a mixed single emitting layer containing N,N'-diphenyl-N,N'-(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine [TPD] and poly(3-hexylthiophene) [P3HT]. The molar ratio between P3HT and TPD chaged with 1:1, 3:1, 5:1, 3:2 and 5:2. EL intensity of ITO/P3HT+TPD/Mg:In devices is enhanced by addition of TPD into P3HT. This can be explained that the energy transfer occurs from TPD to P3HT. Recombination probability increases in emitting layer because that TPD as hole transport material plays a role more injection hole and Mg:In (3.7eV) electrode has low work function make easily electron injection. ITO/P3HT+TPD(5:2)/Mg:In devices emit orange-red light at 28V.
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In this study, we have investigated the holography recording and reconstruction of the polarization state in chalcogenide
$A_{s40}Ge_{10}Se_{15}S_{35}4 thin films using a He-Ne laser light(633nm). The thickness of thin films is a 8677${\AA}$ and 9093${\AA}$ . A He-Ne laser used to probe and record of the grating. Also the polarization state of object beam modulated with a$\lambda/4$ wave plate. The polarization state of the +lst order diffracted beam generated by readout of the grating with a linearly polarized reference beam. It was the same-handed polarization state as the polarization state of the recording beam. The diffraction efficiency of circularly polarized recording represented higher than other polarization state. -
By RF magnetron sputtering ZnGa
$_2$ O$_4$ thin films were prepared on Si(100) wafer in terms of RF power, substrate temperatures and Ar/O$_2$ flow rate. Crystallographic orientation was characterized by x-ray diffraction(XRD). Surface morphology and microstructure were observed by scanning electron microscope(SEM). Photoluminescence(PL) measurement was employed to observe the emission spectra of ZnGa$_2$ O$_4$ films. The influences of various deposition parameters on the properties of grown films were studied. PL spectrum of ZnGa$_2$ O$_4$ thin films showed broad band luminescence spectrum. -
In the resent years, the Thin Film Transistor Liquid Crystal Display(TFT-LCD) have trend toward larger panel sizes and higher spatial and/or gray-scale resolution. In this trend, Because of its low field effect mobility, a-Si TFT is change to poly-Si TFT. In this paper, both effective-medium model of poly-Si TFTs and empirical capacitance model are applied to Pixel Design Array Simulation Tool (PDAST) and the pixel characteristics of TFT-LCD array were simulated, which were compared with the results calculated by Aim-Spice.
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In this paper, the effects of negative and positive bias stress on p-channel poly-Si TFT's fabricated by excimer laser annealing have been investigated After positive and negative bias stress, transcon-ductance(g
$_{m}$ ) is increased because of a reduction of the effective channel length due to the injected electron in the gate oxide. In the positive bias stress, the injection of hole is appeared after stress time of 3600sec and g$_{m}$ is decreased. On the other hand, the gate voltage at the maximum g$_{m}$ , S-swing and threshold voltage(V$_{th}$ ) are decreased because of the interface state generation due to the injection of electrons into the gate oxide.e.ide.e. -
Carbon nanotube(CNT) was successfully grown on Ni-W alloyed substrate by applying PECVD technique(Plasma Enhanced Chemical Vapor Deposition). As a catalyst, Ni-W alloyed substrate was prepared by mechanical alloying method. In order to find the optimum growth condition, initially two different types of gas mixtures such ac
$C_2$ H$_2$ -H$_2$ and$C_2$ H$_2$ -MH$_3$ were systematically investigated by adjusting results on the mixing ratio in temperature range of 500 to 80$0^{\circ}C$ . In this work, we will report the preliminary results on the CNT processed by PECVD, which were characterized by XRD, SEM and TEM. Finally we will evalute the effect on CNT growth by changing many processing parameters, such as typical gas, mixing ratio between 2 mixture, plasma power and etc. -
We fabricated organic electroluminescent (EL) devices with single layer of poly(3-dodeoylthiophene) (P3DoDT) hlended with different amounts of poly(N-vinylcarbazole) (PVK) as a emitting layer. The molar ratio between P3DoDT and PVK changed with 1:0, 2:1 and 1:1. To improve the external quantum efficiency of EL devices, we applied insulating layer, LiF layer, between polymer emitting layer and Al electrode. All of the devices emit orange-red light and it's can be explained that the energy transfer occurs from PVK to P3DoDT. In the voltage-current and voltage-brightness characteristics of devices applied LiF layer, current and brightness increased with increasing applied voltage. The brightness of the device have a molar ratio 1:1 with LiF layer was about 10 times larger than that of the device without PVK at 6V. Electrical impedance properties of ITO/emitting layer/LiF/Al devices were investigated. In the Cole-Cole plots of impedance data, one semicircle was observed. Therefore, the equivalent circuit for the devices can be designed as a single parallel resistor and capacitor network with series resistor.
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Effects of liquid crystal (LC) alignment using an in-situ photo-alignment method by linearly polarized UV exposure during imidization of polyirnide (PI) on the two kinds of PI surfaces with side chain were investigated. The generated pretilt angle in nematic (N) LC using an in-situ photo-alignment method was smaller than that of a conventional photo-alignment method for short UV exposure time. Also, the pretilt angle of the NLC using an in-situ photo-alignment method increases with increasing UV exposure time on the two kinds of the PI surfaces. Finally, the pretilt angle of NLC can be improved by annealing treatment.
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ITO(Indium Tin Oxide) films for transparent electrodes of FPD(Flat Panel Display) were patterned in atmosphere using laser. A pulse type(repetition rate of 10 Hz) Q-switched Nd:YAG laser which can generate the fundamental wavelength at 1064 nm or its harmonics(532, 266 nm) was used for Patterning of the ITO film. In case of using the second harmonic(532 nm) of Nd:YAG laser, the ITO film(thickness of 20 nm) was removed clearly with a laser fluence of 5.2 J/
$\textrm{cm}^2$ and a beam scan speed of 200${\mu}{\textrm}{m}$ /s. But the glass substrate was damaged when the laser fluence was over 5.2 J/$\textrm{cm}^2$ . We discussed the etching mechanism of the ITO film using Nd:YAG laser with observation of the etching characteristics including a depths and widths of ITO films as a function of laser fluence using SEM(Scanning Electron Microscopy) and surface profiler($\alpha$ -step 500). -
We analyze the variation of coupling length as a function of the waveguide width for a directional coupler. It is interesting that the coupling length is not monotonic function of waveguide width for a given distance between the centers. The waveguide width for a maximum coupling length can be utilized for the optimum design of a directional coupler.
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본 논문에서는 PELD의 구조, 발광원리, 기본사항, 특징, 용도 등을 살펴보고 PELD의 휘도, 색도 등을 측정하여 이의 특성을 분석한다.
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Although for its great amount and cleanness solar energy has been studied a lot as a substitute one, it is limitedly being utilized in heating water and partly in special usage for high cost of installing solar cell in Korea. Consider domestic shortage of natural energy resources and environmental issue by the Climate Agreement treated in 1994, it is urgently needed to study the practical application of solar energy as a substitute one. Therefore in order to increase the efficiency of solar cell and decrease its price, this study treats the course of designing and manufacturing the panel that connects sunlight by fixing reflector.
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Ferroelectric 0.05PZN-xPZT(90/10)-(0.95-x)PZT(10/90) (x=0.65, 0.85) specimens were fabricated by the mixed-oxide method and cold-pressing method using sol-gel derived PZT(90/10) and PZT(10/90) powders. All specimens show a uniform ferroelectric grain without the presence of the pyrocholre phase. Average grain size increased with an increase in sintering temperature, the value for the x=0.65 specimen sintered at 125
$0^{\circ}C$ was 14.4${\mu}{\textrm}{m}$ . The dielectric constant and dielectric loss of the x=0.65 specimen sintered at 125$0^{\circ}C$ were 1247, 2.05%, respectively. All specimens showed fairly good temperature and frequency stability of dielectric constant with the range from -2$0^{\circ}C$ to 6$0^{\circ}C$ and 100Hz to 10MHz. The coercive electric field and the remanent polarization of x = 0.65 specimen sintered at 125$0^{\circ}C$ were 8.5 kV/cm and 13$\mu$ C/cm$^2$ , respectively. -
Antimony doped tin oxide (ATO) thin films were deposited at room temperature by reactive ion-beam sputter deposition (IBSD) technique in oxidizing atmosphere utilizing Sb and Sn metal targets. Effect of Sb doping concentration, film thickness and heat treatment on electrical and optical properties was investigated. The thickness of as-deposited films was controlled approximately to 1500
$\AA$ or 2000$\AA$ , and Sb concentration to 10.8 and 14.9 wt%, as determined by SEM and XPS analyses. Heat treatment was performed at the temperature from 40$0^{\circ}C$ to 80$0^{\circ}C$ in flowing$O_2$ or forming gas. The resulting ATO films showed widely changing electrical resistivity and optical transmittance values in the visible spectrum depending on the composition, thickness and firing condition. -
We have studies on the Microstructures and densities as a function of forming pressures and the magnetic properties of the specimens with additive Bi
$_2$ O$_3$ that sintered at 95$0^{\circ}C$ for 4.5 hours for synthesizing optimal Ni-Cu-Zn ferrite. Green density rose generally as Forming pressure increased from 1.7 ton/cm$^2$ to 2.5 ton/cm$^2$ and Cold Isostatic Pressure(CIP) method was more effective than Die Pressure(DP) method to high green density. Forming pressure had no influence on apparent density but on the other hand Bi$_2$ O$_3$ contents were strongly dominant to appaernt density than forming pressure. Bi$_2$ O$_3$ liquid phases created during sintering process promoted sintering and grain growth so that apparent density, grain size and permeability increased compared to that of the specimens which were sintered with non-additive Bi$_2$ O$_3$ . -
ZnO varistor is studied to sintering condition and mixing condition for the improvement to non linear of electrical characteristics. In this paper, ZnO varistor, ZnO-Bi
$_2$ O$_3$ -Y$_2$ O$_3$ -MnO-Cr$_2$ O$_3$ -Sb$_2$ O$_3$ series, is fabricated with Sb$_2$ O$_3$ mol ratio(0.5~4[mol%]) and sintered at 1250[$^{\circ}C$ ] for 2 hours. The grain size to Sb$_2$ O$_3$ moi ratio was measured by fractal mathematics. The ZnO varistors that Sb$_2$ O$_3$ mot ratio is 1[mol%] were shown small grain size because of spinel phase. The fractal dimension were increased with increasing of Sb$_2$ O$_3$ mo ratios. The capacitance of ZnO varistors with increasing of Sb$_2$ O$_3$ additive in voltage-capacitance characteristics was decreased by small grain size. -
The modified Moonie(Cymbal) transducer has been investigated for an accelerometer application. This paper present a wind-mill type ultrasonic motors using ternary piezoelectric ceramics and aluminum endcaps applied by cymbal transducer. The maximum displacement was increased depend on applied voltage and layer number. The multi-layer was fabricated by tape casting using doctor-blade process. The maximum displacement of multi-layered ultrasonic motor was much higher than that of one-layered.
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Film bulk acoustic resonator (FBAR) using AIN reactively sputtered at room temperature was fabricated. The FBAR is composed of a piezoelectric aluminium nitride thin film, top electrode of Al and bottom electrode of Au connected by a short (200
${\mu}{\textrm}{m}$ ) transmission line on both sides and reflector layers of SiO$_2$ - W Pair. The active areas of Al and Au were patterned using 150${\mu}{\textrm}{m}$ diameter shadow mask. The series resonance frequency (fs) and the parallel resonance frequency (fp) were measured at 1.976 GHz and 2.005 GHz, respectively. The minimum insertion loss and return loss were 6.1 dB and 37.19 dB, and the quality factor (Q) was 4261. -
The 0.6Ba(Zn
$_{1}$ 3/Ta$_{2}$ 3/)O$_3$ -0.4Ba(Co$_{1}$ 3/Nb$_{2}$ 3/)O$_3$ ceramics were prepared by the conventional mixed oxide method. The structural properties of the 0.6BZT-0.4BCN ceramics with the sintering temperature were investigated by XRD, SEM. The 0.6BZT-0.4BCN ceramics had a complex-perovskite structure. Increasing the sintering temperature, the peak intensity of the superstructure reflection plane were increased and the density and ordering were increased. The density of the 0.6BZT-0.4BCN ceramics sintered at 1475$^{\circ}C$ was 6.455[g/cm$^3$ ]. -
The
$Al_2$ O$_3$ specimens were prepared by the conventional mixed oxide method with addition La$_2$ O$_3$ , Bi$_2$ O$_3$ . The specimens were sintered at 15$25^{\circ}C$ , 5hr., in air. The structural properties of the specimens were investigated by XRD and SEM. The$Al_2$ O$_3$ ceramics with dopants had hexagonal structure and didn't show secondary phases. In the case of specimens with 0.25wt% La$_2$ O$_3$ and 0.25wt% Bi$_2$ O$_3$ bulk densities and lattice parameter of c/a were 3.818g/cm$^3$ , 3.783g/cm$^3$ and ca=2.725, c/a=2.723, respectively. The bulk densities of$Al_2$ O$_3$ ceramics were decreased with dopants. -
In this study, the temperature coefficient of resonant frequency(TC
$F_{r}$ ), dielectric and piezoelectric properties of Pb[(S$b_{1}$ 2/N$b_{1}$ 2/)$_{0.0035}$ -(M$n_{1}$ 3/N$b_{2}$ 3/)$_{0.0065}$ -(Z$r_{x}$ $Ti_{1-x}$ )$_{0.90}$ ]$O_3$ ceramics is investigated with Zr/Ti ratio. The dielectric constant and electromechanical coupling factor($k_{p}$ ) showed the highest values of 1257, 0.562 respectively when the Zr/Ti ratio is 49.5/50.5. The mechanical quality factor($Q_{m}$ ) is the lowest value of 713 when the Zr/Ti ratio is 49.5/50.5, and increased with the decrease of the Zr/Ti ratio. The temperature coefficient of resonant frequency(TC$F_{r}$ ) change abruptly at the morphotropic phase boundary(MPB), which is between the rhombohedral phase with highly negative TC$F_{r}$ of -106ppm/$^{\circ}C$ and the tetragonal phase with highly positive TC$F_{r}$ of +64pp$m^{\circ}C$ as Zr/Ti ratio changes from 50/50 to 49.5/50.5.50.5..5.50.5.5. -
Reactive radio frequency (RF)magnetron sputter with incident angle has been used to deposit AlN thin film on a crystalline Si substrate. (002)Preferred orientation of AlN thin film has been obtained at low sputtering pressure. Also it has been shown that depostion rate of AIN thin film is affected by fraction Ar and
$N_2$ partial pressure. But substrate temperature didn't affect depostion rate of AIN thin film . As sputtering pressure increased preferred orientation degraded. The internal stress changed from tensile stress to compressive stress as fraction of$N_2$ partial pressure increased. At low nitrogen partial pressure cermet$^{[1]}$ AIN thin film is obtained. -
For improvement of B constant in
$CaMnO_3$ -$CaTiO_3$ perovskite type thermistors, effect of$Cr_2$ $O_3$ addition ranged from 0.0wt% to 5.0wt% on electrical properties were investigated with contents and sintering temperatures in the view of crystal and microstructures. The solubility limit of Cr$_2$ O$_3$ was up to 0.5wt% judging from the result of lattice parameter. The grain size was decreased and the resistance at room temperature and B constant were increased with the addition of$Cr_2$ $O_3$ .On particular, B constant of$CaMnO_{3-x}$ $Cr_2$ $O_3$ system was increased greatly from 1574k to 2598k at 0.5wt%$Cr_2$ $O_3$ addition. Further addition of$Cr_2$ $O_3$ , however, resulted in the decrease of the resistance and B constant due to the$Cr_2$ $O_3$ precipitation on the grain boundary. As the$CaTiO_3$ contents increased in the$CaMnO_3$ -$CaTiO_3$ system, the resistance at room temperature and B constant were highly changed. -
The piezoelectric properties and the doping effect of N
$b_2$ $O_{5}$ and Mn$O_2$ for 0.95PbZ$r_{x}$ $Ti_{x}$ $O_3$ +0.05Pb(M$n_{0.42}$ $W_{0.26}$ S$b_{0.32}$ )$O_3$ compositions have been investigated. In the composition of 0.95PbZ$r_{0.54}$ $Ti_{0.46}$ $O_3$ +0.05Pb(M$n_{0.42}$ $W_{0.26}$ S$b_{0.32}$ )$O_3$ the Values Of$k_{p}$ find and$\varepsilon$ $_{33}$ $^{T}$ are maximized, but$Q_{m}$ Was minimized ($k_{p}$ =0.51,$Q_{m}$ =1750). The grain size was suppressed and the uniformity of grain was improved with doping concentration of N$b_2$ $O_{5}$ for 0.95PbZ$r_{0.54}$ $Ti_{0.46}$ $O_3$ +0.005Pb(M$n_{0.42}$ $W_{0.26}$ S$b_{0.32}$ )$O_3$ sample. The values of$k_{p}$ increased and the values of$Q_{m}$ slightly decreased when 0.5 wt% of N$b_2$ $O_{5}$ is doped. And the values of$k_{p}$ was the same formation of the N$b_2$ $O_{5}$ dopant when 0.5 wt% of M$n_2$ $O_{5}$ is doped. But the values of$Q_{m}$ was deeply decreased when 0.5 wt% of Mn$O_2$ is doped. As a experiment results under high electric field driving, this piezoelectric ceramics are very stable. Conclusively, piezoelectric ceramic compsiton investigated at this paper is suitable for application to high power piezoelectric devices.. devices..ices.. devices.. -
(M
$n_{l-x}$ M$g_{l-x}$ )F$e_{2+x}$ $O_4$ (x=0.0, 0.025, 0.1, 0.2) for NTC(negative temperature coefficient) thermistor was prepared by calcining at 80$0^{\circ}C$ and sintering at from 1100 to 130$0^{\circ}C$ with 5$0^{\circ}C$ intervals while x was varied from 0.0 to 0.025, 0.1 and 0.2. The best linear property was obtained in the based specimen sintered at 120$0^{\circ}C$ with x=0.1 composition. Thermistor parameter,$B_{25~85^{\circ}C}$ , was in the range of 5000~ 7300 [K]. Temperature coefficient of resistance,$\alpha$ $_{25^{\circ}C}$ , was -5.2 %/$^{\circ}C$ . The results showed the possibility that Mn-Ni-Co based thermistor could be substituted by the composition used in this study was confirmed.med.d. -
An ultrasonic linear motor was composed of a slider and a stator vibrator including piezoelectric material and elastic material. The ultrasonic linear motors mainly consist of an ultrasonic oscillator which generates elliptical oscillations. Elliptical oscillations are generated by synthesizing two degenerated modes. Direction of vibratory displacement was analyzed by employing the finite element method. So, we could recognize that the direction of the slider's movement was controlled by changing the Phase difference of the drive voltage.
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In this paper, we calculated equivalent circuit of Langevin type ultrasonic vibrator and designed a vibrator whose resonant frequency is 50(KHz). FEA (Finite Element Analysis) was employed to calculate the resonant frequencies and maximum displacements of designed vibrators. The computer calculated resonant frequencies were approached to the designed one. As AC voltage input the maximum displacements were shown sinusoidal changes. Terminal input admittance over a frequency range spanning the resonant frequency were calculated. ANSYS was employed to calculate resonant frequencies, displacements and terminal input admittance of vibrators
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This paper was to measure the structure, piezoelectric properties of 0.05Pb(
$A1_{0.5}$ $Nb_{0.5}$ )-0.95Pb($Zr_{0.52}$ $Ti_{0.48}$ )$O_3$ ceramics dopped with additive after creating the specimens with a general method. It is shown that X-ray diffraction pattern variation of lines (200) have tendency to move in simple peak by addition of additive. According to the increase of$Cr_2$ $O_3$ , tetragonality hardly have variation, according to the increase of$Fe_2$ $O_3$ , tetragonality decreased on the whole. According to dopping with$Cr_2$ $O_3$ and$Fe_2$ $O_3$ , electromechanical factor(kp) largely increased, in case of sintering at$1200^{\circ}C$ kp was maximum value of 40.04[%] at$Cr_2$ $O_3$ 0.3wt%, and maximum value of kp 42.9 [%] at$Fe_2$ $O_3$ , 0.9wt%. In case of sintering at 120$0^{\circ}C$ , mechanical duality factor(Qm) was maximum value of Qm 268.8 at$Cr_2$ $O_3$ , 0.9 wt%. -
The 3-D
$31.5 $\times$ 31.5$\times$ 2.5mm$^3$ model of contour vibration mode piezoelectric transformer with Pb($Ni_{1/2}$ $W_{1/2}$ )$O_3$ -Pb(Zr,Ti)$O_3$ ceramics was simulated by ANSYS according to the dot size 17, 18, 19, 20, 21$mm\phi$ and analyzed the results. The mechanical quality factor of the 3-D model was decreased with the dot size and increased as 2605 at 20$mm\phi$ and after then decreased again. The output voltage of that sample was 74123 [V] and the maximum stress of the dot electrode at that sample was 288[$10^7$ N/$m^2$ ] and the maximum displacement of the ring electrode at that sample was 128 [$\mu\textrm{m}$ ]. -
ITO (indium tin oxide) thin films on PET (polyethylene terephthalate) and glass substrates have been deposited by a dc magnetron sputtering without heat treatments such as substrate heater and post heat treatment. Each sputtering parameter during the sputtering deposition is an important factor for the high quality of ITO thin films deposited on polymeric substrate. Particularly, the material, electrical and optical properties of as-deposited ITO oxide films are dominated by sputtering power, oxygen partial pressure and films thickness. As the experimental results, the XRD patters of ITO films are influenced by sputtering power and pressure. As the power and pressure are increased, (411) peak is grown suddenly. the electrical resistivity is also increased, as the sputteing power and pressure are increased. Transmittance of ITO thin films in visible light ranges is lowered with increasing the sputtering power and film thickness. Reflectance of ITO films in infia-red region is decreased, as the power and pressure is increased.
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This paper present a new sort of multilayer piezoelectric ceramic transformer for the application to AC-adapters. This piezoelectric transformers operate in the second and third length extensional vibration mode. And the output performance of two types of piezoelectric transformers are compared by ANSYS, which is one of the FEM analysis program. As a result the minimum displacement was occurred at the two points in second length extensional vibration mode and three point in third length extensional vibration mode. One is the middle of input and the other is middle of output parts. And output voltage was inversely decreased by increasing number of output layers. Also The third mode type is shown higher power transition ratio than the second mode type.
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Change of dielectric loss of use in high relative permitivity capacitor BaTiO
$_3$ ceramic depends on Mn doping have been investigated. The powders used in this study were commercial BaTiO$_3$ , TiO$_2$ and, MnCO$_3$ . Sample was fabricated by conventional ceramic process. The quantity of Mn was changed gradually from 0.lmol% to 10mo1%. The sintering densities were reduced with increasing amount of MnCO$_3$ . This result is because of increase of low density second phase BaMnO$_3$ . When the samples were doped by over 0.2mol% of MnCO$_3$ , average grain sizes were enlarge to several tens${\mu}{\textrm}{m}$ . The dielectric losses were reduced by Mn doping to lmol% but, increased from lmol% to 10mo1% gradually. -
The (Sr
$_{1-x}$ Ca$_{x}$ ) thin films ale deposited OR 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 at SCT15 thin film. 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 temperature properties of the dielectric loss have a stable value within 2% independent of the substitutional contents of Ca.Ca. -
The spinel L
$i_{1-x}$ M$n_2$ $O_4$ has been synthesized by the solid-state reaction. L$i_{l-x}$ M$n_2$ $O_4$ which includes a mixture of LiOH .$H_2O$ and Mn$O_2$ prepared by preliminary heating at 35$0^{\circ}C$ for 12hr. L$i_{l-x}$ M$n_2$ $O_4$ fired at temperature range from 75$0^{\circ}C$ for 48hr. The structure and the electrochemical characteristics of spinel to L$i_{1-x}$ M$n_2$ $O_4$ which is fabricated by changing sintering condition from starting materials are investigated. The cyclic voltammetric measurement was performed using 3 electrode cells. Electrode specific capacity and cycle life behavior were tested in a 3.0~4.2V range at a constant current density of 0.45mA/c$m^2$ . To improve the cycle performance of spinel L$i_{l-x}$ M$n_2$ $O_4$ as the cathode of 4V class lithium secondary batteries, spinel phases L$i_{1-x}$ M$n_2$ $O_4$ were Prepared at various lithium. The results showed that discharge capacity of L$i_{l-x}$ M$n_2$ $O_4$ varied at lithium quantity decrease with increasing lithium add quantity. The discharge capacities of L$i_{0.925}$ M$n_2$ $O_4$ and LiM$n_2$ $O_4$ revealed 108 and 117mAh/g, respectively.spectively.y. -
The purpose of this study is to manufacture and test a thermoelectric generator which converts unused energy from close-at-hand sources, such as garbage incineration heat and industrial exhaust, to electricity. A manufacturing process and the properties of a thermoelectric generator are discussed before simulating the thermal stress and thermal properties of a thermoelectric module located between an aluminum tube and alumina plate. We can design the thermoelectric modules having the good properties of thermoelectric generation. Resistivity of thermoelectric module for thermoelectric generation consisting of 62 cells was 0.15-0.4
$\Omega$ Developed thermoelectric modules can be expected th have better properties than thermoelectric cooling modules above$70^{\circ}C$ in temperature difference between hot and cold ends. -
Diamond thin films were synthesized on WC-Co substrate at various experimental parameters using 13.56MHz RF PACVD(radio frequency plasma-assisted chemical vapor deposition). In order to increase the nucleation density, the WC-Co substrate was polished with 3
$\mu\textrm{m}$ diamond paste. And the WC-Co substrate was pretreated in HNO$_3$ : H$_2$ O = 1:1 and O$_2$ plasma. In H$_2$ -CH$_4$ gas mixture, the crystallinity of thin film increased with decreasing CH$_4$ concentration at 800W discharge power and 20torr reaction pressure. In H$_2$ -CH$_4$ -O$_2$ gas mixture, the crystallinity of thin film increased with increasing O$_2$ concentration at 800W discharge power, 20torr reaction pressure and 4% CH$_4$ concentration. -
Thin films of vanadium oxide(V
$O_x$ ) have been deposited by r.f. magnetron sputtering from$V_2$ $O_5$ prget in gas mixture of argon and oxygen. Crystal structure, surface morphology, chemical composition and bonding properties of films in-situ annealed in$O_2$ ambient with various heat-treatment conditions are characterized through XRD, SEM, AES, RBS and FTIR measurements. The filrns annealed below 200$^{\circ}C$ are amorphous, and those annealed above 30$0^{\circ}C$ are polycrystalline. The growth of grains and the transition of vanadium oxide into the higher oxide have been obsenred with increasing the annealing temperature and time. The increase of O/V ratio with increasing the annealing temperature and time is attributed to the diffusion of oxygen and the partial filling of oxygen vacancies. It is observed that the oxygen atoms located on the V-0 plane of$V_2$ $O_5$ layer participate more readily in the oxidation process. -
The current-voltage characteristics of the sandwich system at different annealing temperatures and different bias voltages have been studied. In order to prepare the Al/V
$O_X$ /Al sandwich devices structure, thin films of vanadium oxide(V$O_X$ ) was deposited by r.f. magnetron sputtering from$V_2$ $O_5$ target in 10% gas mixture of argon and oxygen, and annealed during lhour at different temperatures in vacuum. Crystall structure, surface morphology, and thickness of films were characterized through XRD, SEM and I-V characteristics were measured by electrometer. The films prepared below 20$0^{\circ}C$ were amorphous, and those prepared above 300$^{\circ}C$ were polycrystalline. At low fields electron injected to conduction band of vanadium oxide and formed space charge, current was limited by trap. Conduction mechanism at mid fields due to Schottky emission, while at high fields it changed to Fowler-Nordheim tunneling effects. -
AIN thin films have been prepared by reactive sputtering method, using facing targets sputtering system with a DC power supply which can deposit a high quality thin film and control deposition condition in all range of nitrogen. The crystallographic characteristics of AIN thin films on N
$_2$ /Ar ratio was investigated by alpha-step and X-ray diffraction. As a result, the AIN film deposited at the pressure ratio of the nitrogen of 30% revealed strong X-ray diffraction intensity under substrate temperature 25$^{\circ}C$ and applied current 0.4A. -
We synthsized the P-nonyloxyazobenzene derivatives with functiona1 structures and carried out this experiment to observe Photoisomerization irradiated by alternate lights. We found that it was reversibly induced to cis-trans photoisomerization in several solvents. Spreading solutions for the LB films were prepared in chloroform(1.2
${\times}$ 10$\^$ -2/ mmol). As a result it is found that the absorption spectra of the Langmuir-Blodgett(LB) monolayer films was induced to photoisomerization by alternative irradiation lights, temperatures respectively. -
A flat type microgas sensor was fabricated on the p-type silicon wafer with low stress S
$i_3$ $N_4$ , whose thickness is 2${\mu}{\textrm}{m}$ using MEMS technology and its characteristics were investigated. W$O_3$ thin film as a sensing material for detection of N$O_2$ gas was deposited using a tungsten target by sputtering method, followed by thermal oxidation at several temperatures (40$0^{\circ}C$ ~$600^{\circ}C$ ) for one hour. N$O_2$ gas sensitivities were investigated for the W$O_3$ thin films with different annealing temperatures. The highest sensitivity when operating at 20$0^{\circ}C$ was obtained for the samples annealed at$600^{\circ}C$ . As the results of XRD analysis, the annealed samples had polycrystalline phase mixed with triclinic and orthorhombic structures. The sample exhibit higher sensitivity when the system has less triclinic structure. The sensitivities,$R_{gas}$ $R_{air}$ operating at 20$0^{\circ}C$ to 5 ppm N$O_2$ of the sample annealed at$600^{\circ}C$ were approximately 90. 90. -
Maxwell displacement current(MDC) was generated when the area per molecule was about 140
${\AA}$ $^2$ and 100${\AA}$ $^2$ . MDC were investigated in connection with monolayer compression cycles. It was found that the maximum of MDC appeared at the molecular area just before the initial rise of surface pressure in compression cycles. The absorption spectra of polyamic acid containing p-methoxyazobenzene in a mixture of N,N-dimethylacetamide(DMAc) and benzene(1:1 by volume) solution was induced photoisomerization by UV and visible light irradiation. The precursor LB film was heated in a vacuum dry oven at 120$^{\circ}C$ in order to convert it into the LB film of polyimide. The absorption spectra of LB films were also induced photoisomerization by UV and visible light irradiation. -
We investigated UV-vis absorbances to observe photoisimerization and effect of temperature using the mixture solution in chloroform and the LB monolayer mixed with DLPE and 8A5H containing azobenzene which shows reversible cis-trans isomerization irradiated by alternate lights. We could find that the absorption spectrum of the mixtures solution and LB monolayer was reversibly induced to photoisomerization irradiated by Uv of both and visible lights, in addition the absorbance by alternate temperatures.
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In the recognition of the gases using the quartz crystal rnicrobalance (QCM) coated with the film materials, it is important to obtain the recognition ability of gases, and the stability of film coated above the QCM. Especially, the thickness of film coated above the QCM is decreased according with the using circumstance and time of QCM gas sensor. Therefore, the sensing chararcteristics of film is changed with these. In this paper, we coated the lipid GC materials varing with the blended amount of PVC(Po1y Vinyl Chloride) and solution (Tetra Hydrofan:THF) above QCM to obtain the stability of lipid PC film. QCM gas sensors coated with film materials were measured the frequency change in the chamber of stationary gas sensing system injected 1-hexane, ethyl acetate, ethanol and benzene of 20.4 respectively. Also, we measured the degradation characteristics of QCM gas sensor to show the properties of stability.
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The purpose of this study is to research and develop conducting polymer(CP) composite electrode for supercapacitor. Electrochemical capacitor(supercapacitor) cell of CP composite electrode with 1M LiClO
$_4$ PC bring out good capacitor performance below 4V. The radius of semicircle of CP composite cell with PAn composite electrode adding l5wt%SP270(PAnS15) and PT composite electrode adding 50wt%SP270 (PTS50) was absolutely small. The total resistance of supercapacitor cell mainly depended on internal resistance of the electrode. The discharge capacitance of supercapacitor cell with PTS50(+)/PAnS15(-) in 1st and 20th cycles was 38F/g and 28F/g at current density of 1mA/cm$^2$ . Supercapacitor cell with PTS50(+)/PAnS15(-) showed good capacitance and stability with cycling. -
Conductive Langmuir-Blodgett(LB) films have recently attracted much interest from the viewpoint of ultrathin film conductors at the molecular level. The result shows that the Maxwell-displacement-current(MDC) measuring technique is useful in the detection of phase-transition over the entire range of molecule areas. At the liquid-solid phase transition, a striking feature in the present current measurement was observed; the I-A isotherm for a DPPC monolayer has sharp bend. Dynamic behavior of monolayers in the presence of an external field was also investigated using the current-measuring technique. Dynamic behavier of DPPC monolayer was measured by displacement current when the molecules are stimulated by pressure velocity. As result, it is known that current is generated of higher current pe마 as compression velocity become faster. Also, in order to clarify the reorganization of the lipid monolayers, it is instructive to plot the relationship between I and 1/
$A^2$ . -
In this paper, generation form of displacement current was compared and measured with air-water interfacing induce monolayers which 8A5H with azobenzene and arac.acid mixed. Light response of two monolayers which chain length are different was compared and measured though they are the same isomer. The experimental results are as following; In the displacement current form of mixed monolayers and 8A5H, mixed monolayers which chain length is longer than that of 8A5H caused the displacement current about 40[fA] mole. This is the reason chain length of hydrophobicity in mixed monolayers is longer than that of 8A5H In the case of light stimulus mixed monolayers reacted less than 8A5H about 9[fA]. This is the reason molecule dynamic behaviour in cia and trans was net activated due to its very long chain length.
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In this study,
$\alpha$ -Fe$_2$ O$_3$ thin films were deposited on$Al_2$ O$_3$ substrate by RF magnetron sputtering method from a$\alpha$ -Fe$_2$ O$_3$ target(99.9%). The sputtering atmosphere was Ar and 80%Ar:20%O$_2$ mixture in a total gas pressure of 1~3mTorr. As-deposited$\alpha$ -Fe$_2$ O$_3$ thin films were heated to 300, 400, 500,$600^{\circ}C$ for 5hr in oxygen atmosphere. The structure and the morphology of$\alpha$ -Fe$_2$ O$_3$ thin films were examined by scanning Electron microscopy(SEM) and the crystal structure was analyzed by X-Ray Diffractometer(XRD). The microstructure of the annealed$\alpha$ -Fe$_2$ O$_3$ films exhibits rather gross particle and the grain size was less than 100nm. Since the grain size was very small, the gas sensitivity was expected to be improved. -
Molecular switching in azobenzene mixed monolayers on a water surface was investigated by means of Maxwell displacement current(MDC) measurement. It was found that the change in the vertical component of the dipolemoment of the mixed monolayer during visible light irradiation was almost the same as that flowing during UV light irradiation. Also MDC was generated but it depended on the molar ratio. As a result. It's phtoisomerization progressed by 8A5H in mixed films.
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The purpose of this study is to research and developV
$_2$ O$_{5}$ -SP270 composite electrode for supercapacitor. Property of an electrical double layer capacitor depend both on the technique used to prepare the electrode and on the current collector structure. The study is to research that V$_2$ O$_{5}$ -carbon composite electrode for supercapacitor with different voltage range. Suprcapacitor cell of V$_2$ O$_{5}$ -SP270 composite electrode with 25PVDFLiC1O$_4$ PC$_{10}$ polymer electrolyte bring out good capacitor performance below 3V. The discharge capacitance of SP270 in 1st cycles was 13F/g at 0.1mA/cm$^2$ , 3V. We performed cycle voltammogram, charge/discharge property.y.rty.y. -
Photoreactive multilayer films were prepared using long-chin alkyl diesters of p-phenylenediacrylic acid(p-PDA). In spite of the absence of hydrophilic groups in these molecules, they formed stable monolayers on the water surface when mixed with arachidic acid. Surface showed the presence of a condecsed phase and these monolayer could be transferred onto a substrate with Y-type deposition. The UV spectra of mixed multilayer films showed of absorption peak compared with that in solution. The linear relationship between absorbanoe and the number of layers supports the successful formation of multilayer films.
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The electrochromic properties of
$WO_{3}$ /$MoO_{3}$ and$MoO_{3}$ /$WO_{3}$ double-layers have been systemically studied. The double-layers were made by a e-beam evaporation method and investigated by studying optical modulation, transmittance, and cyclic voltammetry. The devices exhibit good optical properties with wavelength range of 400 to 1100 nm(visible and infrared) during coloration as a function of lithium ion charge injection. It has shown that the double-layer electrochromic thin films are improved the electrochromic properties, but the electrochemical properties are less stable. -
The correlation of surface morphology and magnetic property of NiFe thin films on Si(001) deposited by RF-magnetron sputter has been investigated, using AFM, XRD and MR measurements. During short field annealing for 15 min, there was no significant change in XRD patterns of NiFe thin films. However, the degree of surface roughness was changed with increasing annealing temperature. With variation of surface roughness, there was significant difference in MR characteristics of NiFe thin films. In the case of as-deposited NiFe thin films(T
$\_$ G/ = 150$^{\circ}C$ ) and UFA400 (T$\_$ A/ = 400$^{\circ}C$ ) having smooth surface, good linearity of MR Curve was observed. -
Vanadate glasses in the Li
$_2$ O-P$_2$ O$_{5}$ -V$_2$ O$_{5}$ system containing 10mo1% glass former, P$_2$ O$_{5}$ were prepared by melting the batch in pt. crucib1e followed by quenching on the copper plate. We found that Li$_2$ O-P$_2$ O$_{5}$ -V$_2$ O$_{5}$ glass-ceramics obtained from nucleation of glass showed significantly higher capacity and longer cycle life than conventionally made crystalline LiCoO$_2$ , LiNiO$_2$ and LiV$_3$ O$_{8}$ . In the present paper, We describe electro-chemical properties during crystallization process and find the best crystallization condition of Li$_2$ O-P$_2$ O$_{5}$ -V$_2$ O$_{5}$ g1ass as cathod material. Li$_2$ O-P$_2$ O$_{5}$ -V$_2$ O$_{5}$ glass-ceramics shows superior rechargeable capacity of 220 mAh/g in the cycling between 2.0 and 3.9V.etween 2.0 and 3.9V. -
Deposition of PZT with UV laser ablatio was applied for realization of thin film sensors and actuators. Deposition rate of more than 20nm/min was attained by pulsed KrF excimer laser deposition, which is fairly better than those obtained by the other methods. Perovskite phase was obtained at room temperature deposition with Fast Atom Beam(FAB) treatment and annealing. Smart MEMS(Micro electro-mechanical system) is now a suject of interest in the field of micro optical devices, micro pumps, AFM cantilever devices etc. It can be fabricated by deposition of PZT thin films and micromachining. PZT films of more than 1 micron thickness is difficult to obtain by conventional methods. This is the reason why we applied excimer laser ablation for thin film deposition. The remanent polarization Pr of 700nm PZT thin film was measured, and the relative dielectric constant was determined to about 900 and the dielectric loss tangent was also measured to be about 0.04. XRD analysis shows that, after annealing at 650 degrees C in 1 hour, the perovskite structure would be formed with some amount of pyrochlore phase, as is the case of the annealing at 750 degrees C in 1 hour.
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We have fabricated a sensor system for on-line monitoring the oxygen permeability and diffusivity of six different polymer films using the miniaturized 6 cathode(Ag)-single anode(Ag/AgCl) type hexagonal oxygen electrode. This system consists of multiple input front-end electronics, signal conditioning circuit using the embedded microcontroller 80C196KC, PC interface circuit and PC with the OS for microcontroller and the operating program for this system. The digital low-[ass filter was programmed and the simulated filter characteristics were enough to eliminate the noise from sensor signal. According to the experimental results, the linearity coefficients of the output voltage to oxygen partial pressure for each sensor electrode of six cathode type oxygen sensor are 0.998, 0.997, 0.998, 0.997, 0.997, 0.997 respectively, and the response times are all within 4 minutes.
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The effects of annealing on the electrical and structural characteristics for the rf sputter deposited WO
$_3$ thin film. The sputtered thin films are annealed at 773K for 1 hour in air atmosphere. Oxygen flow rate were changed from 0 to 70% during sputtering. It is observed from the results of the AFM measurement that the average roughness for the rf sputter deposited WO$_3$ thin film would be increased from 2.45 angstrom to 152 angstrom by annealing. The sheet resistance of the sputtered WO$_3$ film is changed from insulting to MOhm after annealing. According to the results of the XRD, the as-deposited films revealed the amorphous state whereas the peaks of X-ray diffraction at 2 theta= 28 degrees and 2 theta = 25 degrees corresponding to the (111) and (200) plane of the WO$_3$ film respectively are observed after annealing. -
The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li polymer battery. The temperature dependence of conductivity, impedance spectroscopy and electrochemical properties of PAN/PVDF electrolytes as a function of a mixed ratio were reported for PAN/PVDF based polymer electrolyte films, which were prepared by thermal gellification method of preweighed PAN/PVDF, plasticizer and Li salt. The conductivity of PAN/PVDF electrolytes was
$10^{-3}$ S/cm.$PAN_{10}$ $PVDF_{10}$ $LiClO_4$ $PC_{5}$ $EC_{5}$ electrolyte has the better conductivity compared to others. The interfacial resistance behavior between the lithium electrode and PAN/PVDF based polymer electrolyte has also been investigated and compare with that between the lithium electrode and the PAN/PVDF based polymer electrolyte. -
Polypyrrole (PPy) was chemically synthesized within the pores of nanoporous polycarbonate (PC) Particle Track-etched Membranes (nano-PTM). Hollow tubules are formed because polypyrrole initially deposits on the surface of the pores walls. By running successive syntheses, we have obtained wires (filled tubules). The redox property of PPy nanotubules was investigated by cyclic voltammetry. The redox potential was lowered as much as 0.5V vs. Ag/AgC1, comparing with electrosynthesized PPy film. It suggests that an electron hopping mechanism of PPy nanotubules was improved. Electric conductivity of PPy nanotubules and nanowire was evaluated. We obtained good electric conductivity of PPy nanotubules even in the neutral state. The conductivity and activation energy were
$10^1$ order at the room temperature and 25.3 meV respectively. -
Spinel phase LiF
$e_{y}$ M$n_{2-y}$ $O_4$ samples are synthesized by calcining a LiOH.$H_2O$ , Mn$O_2$ and F$e_2$ $O_3$ mixture at 80$0^{\circ}C$ for 36h in air. Preparing LiF$e_{y}$ M$n_{2-y}$ $O_4$ showed spinel phase with cubic phase. The ununiform distortion of the crystallite of the spinel LiF$e_{y}$ M$n_{2-y}$ $O_4$ was more stable than that of the pure. The discharge capacity of the cathode for the Li/LiF$e_{0.1}$ M$n_{1.9}$ $O_4$ cell at the first than that of the pure. The discharge capacity of the cathode for the Li/LiF$e_{0.1}$ M$n_{1.9}$ $O_4$ cell at the first cycle and at the 70th cycle was about 113 and 90mAh/g, respectively. This cell capacity was retained about 82% of the first cycle after 70th cycle. Impedance profile of this cell was more stable than that pure. The resistance, the capacitance and chemical diffusion coefficients of lithium ion showed approximately 80$\Omega$ , 36133.87$\mu$ F ; 1.4$\times$ 10$^{-8}$ c$m^2$ $s^{-1}$ , respectively. , respectively.ely. -
The crystallization behavior and dc Conductivities of CuO-Nb
$_2$ O$_{5}$ -V$_2$ O$_{5}$ glasses prepared by quenching on the copper plate were investigated. The conductivities of the glasses were range from 10$^{-4}$ s.$cm^{-1}$ / at room temperature, but the conductivities of the glass-ceramics were 10$^{-3}$ s.$cm^{-1}$ / increased by 10$^1$ order. The linear relationship between In($\sigma$ T) and T$^{-1}$ suggested that the electrical conduction in the present glass system would be due to a small polaron hopping mechanism. The value of activation energy of glass-ceramics heat-treated at 30$0^{\circ}C$ for 12hrs was found to be 0.leV -
Combination of SDB(Si-wafer Direct Bonding) and electrochemical etch-stop in TMAH anisotropic etchant can be used to create a variety of MEMS(Micro Electro Mechanical System). Especially, fabrication of SDB SOI structures using electrochemical etch-stop is accurate method to fabrication of 3D(three-dimensional) microstructures. This paper describes on the fabrication of SDB SOI structures with sealed cavity for MEMS applications and thickness control of active layer on the SDB SOI structure by electrochemical etch-stop. The flatness of fabricated SDB SOI structure is very uniform and can be improved by addition of TMAH to IPA and pyrazine.
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Silicon capacitive pressure sensor has been fabricated by using electrochemical etching stop and silicon-to-glass electrostatic bonding technique. A diaphragm structure is designed to compensate the nonlinear response. A cavity is etched into the silicon to the depth of 2
$\mu\textrm{m}$ by anisotropic etching in 20wt.% TMAH solution at 80$^{\circ}C$ . A fabricated sensor showed 3.3 pF zero-pressure capacitance, 297 pp.m/mmHg sensitivity, and a 7.4 7%F.S. nonlinear response in a 0-1 kgf/cm$^2$ pressure range. -
This paper describes on the temperature characteristics of a SDB(silicon-wafer direct bonding) SOI(silicon-on-insulator) Hall sensor. Using the buried oxide
$SiO_2$ as a dielectrical isolation layer, a SDB SOI Hall sensor without pn junction isolation has been fabricated on the Si/$SiO_2$ /Si structure. The Hall voltage and the sensitivity of the implemented SOI Hall sensor show good linearity with respect to the applied magnetic flux density and supplied current. In the temperature range of 25 to$300^{\circ}C$ , the shifts of TCO(temperature coefficient of the offset voltage) and TCS(temperature coefficient of the product sensitivity) are less than$\pm 6.7$ $\times$ $10^{-3}$ /$^{\circ}C$ and$\pm 8.2$ $\times$ $10^{-4}$ /$^{\circ}C$ respectively. These results indicate that the SDB SOI structure has potential for the development of a silicon Hall sensor with a high-sensitivity and hip high-temperature operation. -
This paper presents the optimized fabrication and thermal characteristics of micro-heaters for thermal MEMS applications using a SDB SOI substrate. The micro-heater is based on a thermal measurement principle and contains for thermal isolation regions a 10
$\mu\textrm{m}$ thick silicon membrane with oxide-filled trenches in the SOI membrane rim. The micro-heater was fabricated with Pt-RTD(Resistance Thermometer Device)on the same substrate by using MgO as medium layer. The thermal characteristics of the micro-heater with the SOI membrane is 280$^{\circ}C$ at input Power 0.9 W; for the SOI membrane with 10 trenches, it is 580$^{\circ}C$ due to reduction of the external thermal loss. Therefore, the micro-heater with trenches in SOI membrane rim provides a powerful and versatile alternative technology for improving the performance of micro thermal sensors and actuators. -
The physical, electrical and piezoresitive characteristics of CrN(chromium nitride) thin-films on silicon substrates have been investigated for use as strain gauges. The thin-film depositions have been carried out by DC reactive magnetron sputtering in an argon-nitrogen atmosphere(Ar-(5∼25 %)Na
$_2$ ). The deposited CrN thin-films with thickness of 3577${\AA}$ and annealing conditions(300$^{\circ}C$ , 48 hr) in Ar-10 % N$_2$ deposition atmosphere have been selected as the ideal piezoresistive material for the strain gauges. Under optimum conditions, the CrN thin-films for the strain gauges is obtained a high electrical 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 gauge factor, GF=11.17. -
We measured 3-dimensional images of the light emitted from plasma display panel(PDP) by using newly proposed scanned point detecting method(SPDM). The SPDM has the point detector with pinhole. The light emitted from PDP cell at the in-focus position can pass through the pinhole and be collected by detector. On the contrary, the light emitted from PDP cell at the out-of-focus positions is focused on the front of or the behind of the pinhole. We could analyze the characteristic of 3-dimensional light emission distribution by SPDM. From 3-dimensional measurement of 828nm, we found that the efficient design of PDP cell, the importance of opening ratio, and the relations between BUS electrode position and discharge intensity are obtained.
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Generally, it is known that many partial discharges are occurred in one voltage cycle. In this case, it is not easy to distinguish between ultrasonic signals caused by the partial discharge. We describes a pattern of the ultrasonic signal by the partial discharge in transformer. The test setup for ultrasonic signal measurement was to simulate a internal partial discharge by using a needle to plane electrodes. We compared the number of partial discharge and ultrasonic signal in one voltage cycle. The results showed that it was possible to distinguish between ultrasonic signals by analysing partial discharge detection method and ultrasonic signal on time domain.
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The wavelet transform is the most recent technique for processing signals with time-varying spectra. In this paper, the wavelet transform is utilized to improved the assessment and multi-resolution analysis of acoustic emission signals generating in partial discharge. This paper especially deals with the assessment of process statistical parameter using the features extracted from the wavelet coefficients of measured acoustic emission signals in case of applied voltage 20[kv]. Since the parameter assessment using all wavelet coefficients will often turn out leads to inefficient or inaccurate results, we selected that level-3 stage of multi decomposition in discrete wavelet transform. We applied FIR(Finite Impulse Response)digital filter algorithm in discrete to suppression for random noise. The white noise be included high frequency component denoised as decomposition of discrete wavelet transform level-3. We make use of the feature extraction parameter namely, maximum value of acoustic emission signal, average value, dispersion, skewness, kurtosis, etc. The effectiveness of this new method has been verified on ability a diagnosis transformer go through feature extraction in stage of acting(the early period, the last period) .
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The electron transport coefficients in
$SF_6$ +$N_2$ gas is analyzed in range of E/P values from 70~240(V/cm$Torr^{-1}$ ) at 2$0^{\circ}C$ by Boltzmann method that using set of electron collision cross sections determined by authors. The result of this Boltzmann simulation such as ionisation coefficient, attachment coefficient, effective ionisation coefficient and breakdown voltage are in nearly agreement with the respective experimental and theoretical for a range of E/P. -
This paper presents a new accelerating aging test facility for distribution lightning arresters. Aging parameters of lightning arrester are moisture ingress, electrical stress and surge absorption and so on. In this system, we applied 13.2kV to 6 samples and controled temperature and humidity of chamber and measured leakage currents of the all samples. Also we developed accelerating aging cycle which consists of -35
$^{\circ}C$ ∼90$^{\circ}C$ temperature and 40%∼90% humidity. Through the aging test we found out the leakage current of aged sample increases rapidly according to the temperature rising. Hereafter we can determine the replacement guide of leakage current for field operating arresters and condition assessment of aged samples through this aging test. -
Recently, Display devices have become important in the information-oriented society and flat display devices are greatly demanded. Liquid crystal display(LCD) represents one of the most promising devices for large size desk-top monitors, notebook PC and car navigation system. However LCD cannot give forth light itself and must have backlight system. The most popular backlighting system is composed of a lighting-guide plate and CCFL as a lighting source. The number of CCFL must increase up if the area of display is increased. So a new backlighting source with high luminance is needed for large LCDs. In this paper, we proposed a surface discharge FFL with the new electrode structure like the needle shaped electrode as the variation of cell structure to high luminance and low power consumption. In comparison with different electrode structure it has low discharge voltage and current and good optical characteristics. So it has better discharge characteristics than different surface discharge FFL and can be fungible for a backlight as a lighting source in LCDs.
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뇌써지가 케이블 심선에 침입할 경우 케이블심선-시스간과 시스와 대지간의 써지임피던스 비에 따라 과 전압이 발생하며, 이와 같이 써지성 과전압이 방식층의 충격내전압치륵 초과할 경우 방식층을 보호하기 위 한 대책이 필요하며 그 보호장치로 절연통 보호장치를 사용하는 것이 일반적이다. 설계, 제작된 절연통 보호장치에 대해 절연저항시험, 동작개시전압시험, 뇌충격제한전압시험, 충격전류시험, 방전하에서 교류내전압시험, 절연성능시험 및 내수성능시험을 실시하여 내수성능시험을 제외한 모든 시험항목에서는 그 결과가 양호하나, 내수성능시험에서는 미세한 홈으로 물이 침투되어 불량이 발생함에 따라 절연통 보호장치는 지 중송전선로에 사용되는 보호장치로서 지중조건에서의 수밀 및 기밀특성 더욱 우수해야 하므로 내수성능시험의 중요성을 인식할 수 있었다.
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Large area plasma source becomes important as the substrate size increases. In this work, four inductively coupled plasma(ICP) unit sources are distributed 2
${\times}$ 2 array. E-ICP concept is applied to the 2${\times}$ 2 array ICP and its effect is examined. Characteristics of the plasma are measured, and photoresist etching is performed with oxygen plasma. Good etching characteristic in terms of etching rate and uniformity can be obtained with E-ICP. -
The etch rate of
$SiO_2$ in Enhanced - Inductive Coupled Plasma (E-ICP) and CW-ICP systems are investigated. As addition of$O_2$ to$CF_4$ gas increases oxide etch rate, E-ICP etching shows the highest etch rate (about 6000A) at an optimized condition with 30%$O_2$ in$CF_4$ 70Hz at the modulation frequency of 70Hz. E-ICP also shows better etch profile than CW-ICP. -
It is important to control the plasma characteristics for high quality plasma process. Recently, a novel method proposed by us, named as Enhanced-ICP, using periodic weak time-varying axial magnetic field added to a normal ICP source, has improved etch characteristics much. Variation of plasma characteristics according to the frequency of time-varying axial magnetic field have been measured and analyzed.
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본 논문은 절연재료의 보이드(void)나 크랙(crack)과 같은 결함이 부분방전을 일으킴으로서 절연재료가 열화되어 최종적으로 파괴에 이른다. 특히 부분방전 중에서 트리잉 열화는 절연재료에 매우 치명적이다. 또한 고전압,고전계 기술분야에서 절연파괴전압이나 일정전압 인가시 수명 시간 데이터는 중요하다. 파괴 통계에 주로 많이 사용하는 와이블 확률 분포를 이용하여 트리잉 파괴에 대한 수명을 평가를 시도하였다. 시료의 형태는 침대 평판전극이고 시료는 저밀도 폴리에틸렌이다 인가 전압은 상용 교류 전압 8,10,12[kV]를 인가하였다. 척도 파라메타는 전압이 증가함에 따라 128.7
$\longrightarrow$ 96.4$\longrightarrow$ 85.4로 감소하고 형상 파라메타는 전압이 증가함에 따라 2.39$\longrightarrow$ 2.19$\longrightarrow$ 2.02로 감소한다. 따라서 시료의 추정 수명은 110분, 81.57분, 49.27분으로 전압이 증가함에 따라 수명이 급격히 단축됨을 알 수 있다. -
The shielding effectiveness of materials is determined by measuring the ratio of the incident electromagnetic power which passes through the material under test. To measure the shielding effectiveness materials made by conductive polymer, the flanged coaxial transmission-line holder based in ASTM D4935-89, was fabricated. This apparatus has dynamic range between 95dB and 120dB in frequency range of 50Mhz-2Ghz. Furthermore, this system can be utilized to measure the shielding effectiveness of materials produced by conductive polymer and can be adapted for shielding materials design.
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Since the concept for the ozone generation using a nonequilibrium electric discharge techniques had been proposed by Siemens, some experimental and theoretical studies on the ozone generation by streamer corona discharge, surface discharge and silent discharge have been performed. In this paper some results on the discharge characteristics of the silent discharge gap with various dielectric materials were reported. Dielectric materials used in this study were pyrex glass, quartz and glass beefs with diameter of 1 mm.
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Recently, the epoxy molded type PT for indoor and applied 25.8kV was often distroyed by degradation of insulation that effected many electric stress and defect of manufactured goods. therefore In this work, We can present a method of solution in the process of produce the PT through analysis of experiments. In order to reduce the PD (Partial Discharge) which was occurred at the insulation material of epoxy resin, we has many tried to remove faults In the process of the products,
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Effects of sintering temperature and time on relative permittivity
$\varepsilon$ $\_$ r/, unloaded quality factor Q$.$ f and temperature coefficient of resonant frequency$\tau$ $\_$ f/ of dielectric resonator materials produced from commercial ZST powder were investigated in some detail. Q$.$ f values, as determined from cavity perturbation method at 1.6 GHz, gradually increased with sintering temperature reaching the maximum at 1420$^{\circ}C$ . However, bulk density and relative permittivity values, which increased with temperature, started to decrease above 1380$^{\circ}C$ . In addition, Q$.$ f values slightly increased with sintering time at the sintering temperature of 1300$^{\circ}C$ ∼1380$^{\circ}C$ , while bulk density and relative permittivity values were approximately constant. It was also found that$\tau$ $\_$ f/ values were not affected by sintering temperature and time within the experimental conditions used. -
Sn-3.5Ag 무연합금을 Cu 및 Alloy42 리드프레임에 납땜접합(solder joint)하고 미세조직, 젖 음성, 전단강도, 시효효과를 측정하여 비교하였다. CU의 경우, 납땜의 Sn기지상안에 Ag
$_3$ Sn$_{5}$ 상이, 그리고 땜납/리드프레임의 경계면에는 1~2$\mu\textrm{m}$ 두께의 Cu$_{6}$ Sn$_{5}$ 상이 형성되었다. Alloy42의 경우, 기지상내에는 낮은 밀도의 Ag$_3$ Sn상만이, 그리고 계면에는 0.5~1.5$\mu\textrm{m}$ 두께의 FeSn$_2$ 이 형성되었다. 한편. Cu에 비해 Alloy42 리드프레임에서 전단강도는 낮았으며, 시효 시간에 따라 전단강도는 모두 감소하였다. 18$0^{\circ}C$ 에서 1주일간 시효처리 후, Cu 리드프레임에는 계면에 η-Cu$_{6}$ Sn$_{5}$ 층이 15-20$\mu\textrm{m}$ 성장하였고, A11oy42 리드프레임에는 기지상내에 AgSn$_3$ 이 조대하게 성장하였으며, 계면에는 FeSn$_2$ 층만이 약$1.5\mu\textrm{m}$ 로 성장하였다.성장하였다. -
The discrete wavelet transform is utilized as processing of neural network(NN) to identifying aging state of internal partial discharge in transformer. The discrete wavelet transform is used to produce wavelet coefficients which are used for classification. The mean values of the wavelet coefficients are input into an back-propagation neural network. The networks, after training, can decide if the test signals is aging early state or aging last state, or normal state.
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In this study, a distance-measurement system was proposed by using principle of the Michelson Interferometer and a fundamental research was carried out. In case of the rnichelson interferometer, relativity distance was measured by relativity-difference of two course of light. But wavelength of light source were changed in this system in order to use interference phenomenon of michelson interferometer in measuring absolutely distance. Wavelength of input signal were changed periodically and were interfered electrically. So absolute distance can be calculated by using
$\Delta\lambda$ and measuring$\eta\Delta$ in electric interference. Nose by a external factor was small in this system because a absolutely distance was measured by phase difference. And a dispersion of noise was small in pulse-echo response because a error was occurred in range of phase difference of signal. Also very wide range can be measured by only single system because informations of distance were acquisited in wavelength level. -
In the winding system, the constant tension control is too important. In this study, we've used a variable PID system as a function of a radius of winding roll. As a result, it was possible to measure a winding roll radius in the real time by making a mathematical model for measuring a winding roll radius. Finally, we've compared PID parameters as a function of winding roll radius after getting PID parameters in terms of the Ziegler & Nichols(ZN) method.
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The microstructure, adhesion strength and conductivity of electroplated Sn-Cu Films on Alloy42 lead Frame were measured for comparison. In the case of electroplated 90Sn10Cu, 99Sn1Cu, Cu
$\sub$ 10/Sn$_3$ Phase was formed and Ni$_3$ Sn$_2$ Phase was formed after 200$^{\circ}C$ , 30min annealing. In the case of electroplated 99Sn1Cu, Cu$\sub$ 10/Sn, Ni$_3$ Sn phases were formed and Ni$_3$ Sn$_4$ , Ni$_3$ Sn$_4$ phases were formed after 200$^{\circ}C$ , 30min annealing. 90Sn10Cu film was measured better uniformity, adhesion strength and conductivity than 99Sn1Cu. -
Laser direct writing of micro-patterned copper lines has been achieved by pyrolytic decomposition of copper formate films (Cu(HCOO)
$_2$ $.$ 4H$_2$ O), as a precursor, using a focused Ar$\^$ +/ laser beam ($\lambda$ = 514 nm) on PCB boards and glass substrates. The linewidth and thickness of the lines were investigated as a function of laser power and scan speed. The profiles of the lines were measured by scanning electron microscope (SEM), surface profiler (${\alpha}$ -step) and atomic force microscopy (AFM). The electrical resistivities of the patterned lines were also investigated as a function of laser parameter using probe station and semiconductor analyzer. we compared resistivities of the patterned lines with that of the Cu bulk, respectively. -
The electrochemical characterization was conducted by the addition of chemically synthesized polyaniline on LiCoO
$_2$ electrode. From the results of XRD and SEM, the phase transition and microstructure were not found. Initial electrochemical characteristics of LiCoO$_2$ electrode for lithium secondary battery were evaluated through the charge/discharge within the range of 4.3 V to 3.0 V versus Li/Li$^{+}$ . Discharge capacity of LiCoO$_2$ electrode without addition of Polyaniline were 160.21 mAh/g. But after addition of polyaniline, lower discharge capacities 25.7 mAh/g was found.d. -
A children's electric shock accidents have broken out because children can easily insert sharp things in 220V receptacle holes. As the test result of pushing force, children's pushing force was about 2-4kg and the pushing force of sharp things was less than 2kg. Therefore, it is reason for electric shock that children's pushing force is large than pushing force of sharp things. We have measured insulation resistance for the receptacles of five companies during 50 weeks in humid condition. As these results, Insulation resistance for the receptacles of J. Co. had rapidly decreased with lapse of time. As the result for investigating the surface of receptacle by SEM and EDX, Al, Fe and Br, which weren't discovered at original form, were produced. Therefore, the receptacles of J. Co. should be the improved in the quality of insulating material because insulation resistance can be decreased in humid environment
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Using the principle of the cross capacitor, a precise system for measuring the electric constants of liquids has been developed. The four electrodes of the cross capacitor were formed around fused-silica tube by plating a gold film. The effect of a non-uniform tube wall ok the measured permittivity was investigated As the individual characteristics of the tubes were determined to be constant, the pure dielectric constants extracted from any effect of the fused-silica material could be precisely derived with uncertainty of less than
${\pm}$ 0.02∼0.05 %. -
This paper present the result of the flashover properties of inulators due to artifitial pollution. For this study, a mini fog chamber has been fabricated with transparent acryl which has the merit in observasion and electrical insulation. All the experiment was carried in mini fog chamber. Though non-souble contaminant do not distribute on the electric conductivity of contaminant and contaminated insulator, that influence on the flashover characteristics of insulators. with the result, we assume phenomenon caused with the hygroscopic property of non-soluble contaminant.
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The chargers for DC power supply of the contro1lers, which have been installed in the relay rooms in 345/154kV substations of KEPCO, lag in both aspects of technique and performance. Moreover, as they are SCR-based, they dont meet the performance requirements of todays digital and automated controllers. Now two controllers are running in pair and one of those is for reservation. There are lots of troubles because the patrol engineering team has to replace them manually whenever they are out of order. So it is expected to bring convenience if the charger replacement is automated. Also, the existing chargers take much space, weight and cost - which have increased the need of development to make them smaller, less expensive, and have high quality. We will develop a charger system which has one fifth of the weight of the existing system by double-integrating the volume. The new system will be ready for a future full unmanned system with integrated pores for remote control, state-of-the-art digital features, and more than 90% efficiency/power factor against 80% efficiency/power factor of the existing system.
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This paper provides the result of the analysis of the lightening arresters which were disconnected from the power line due to the overvoltage having high current. The effect of thermal runaway on the microstructures of lightening arrester's block was intensively investigated. The chance of the microstructures of the blocks was limited only on the breakdown paths and near them. Also even though a disconnector was disconnected from the arrester, some of the lightening arrester were showed normal characteristics.
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This paper present the result of the investigation, the electric properties of insulators due to non-soluble contamination. In general, the humidity and the amount of soluble salts such as NaCl, MgCl
$_2$ are the most dominant factor. Though the non-soluble do not distribute on conductivity of contaminant layer, that has the hygroscopic property. For this study, we make a mini-fog chamber with transparent acryl and the kaoline was used for non-soluble contaminant. The kaoline was applied with sprayer to get the specific ESDD and NSDD value, then the specimen was dried and installed horizontally. And to measure the leakage current a DAS system was developed with LabView. With the result, we could know the influence of non-soluble content and the relationship between NSDD and ESDD. -
This paper present the result of the investigation, the distribution of salt contamination with the influence of geographical condition. To get the ESDD data, a conventional brush washing method was adapted, and IC(ion chromatography) was used to measure the quantity of anions, such as Cl
$\^$ -/ and SO$_4$ $\^$ 2-/. And we make an analysis on the distribution of salt contamination with the increase of distance from shore. With 10 month ESDD data, we seek the 95% ESDD value with interpolation method. With these analyses, we had obtained the formulation concerned with the distance from sea. And could know the composition of contamination. -
Today, electrical machine is being large capacitor and EHV(Extra High Voltage) of power equipment is a need of high reliability of insulating matetials. Therefore, it is a need of fixed appraisement of lifetime to used data of breakdown. This paper studied a development of the program for estimation the lifetime of insullating materials and the long-time breakdown voltage by experimentation. The estimation program is based on the "Inverse Power Law", defined V
$\^$ n/t is constant. After gaining the life exponent n, it is mapping the long-time breakdown voltages. On the base of life exponent, the estimation of lifetime and usefulness of the insulation systems are possible, furthermore easy calculation is possible. -
The acoustic characteristics radiated from the acoustic transducer with metal-piezoceramic laminated circular plate were simulated. The Vibrational modes of metal-piezoceramic laminated circular plates were calculated by using the finite element method. After meshing the inside closed boundary of the acoustic transducer, the pressure gradients and the isotaric lines were calculated for the various frequencies. It has been observed that the characteristics of the sound pressure calculated for the various frequencies. Also, the directivity patterns and the sound pressure radiated from the acoustic transducer were calculated by 2-dimensional analysis.
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Optimization of the biphenyl chloromethylation process with para-formaldehyde has been investigated in the presence of ZnCl
$_2$ with HCI gas by the Box-Wilson method of mathematical planning of experiment. The 4,4'- (dichloromethyl)-biphenyl yield dependence on the biphenyl para-formaldehyde ratio, temperature and reaction duration has been studied. A mathematical model of the process has been developed and optimal conditions for the biphenyl chloromethylation procedure has been determined. -
In this study, the physical properties of the acoustic element and case with metal-piezoelectric ceramics were analyzed. The dielectric and piezoelectric properties of 0.5 wt% MnO
$_2$ and NiO doped 0.1Pb(Mg$\_$ 1/3Nb$\_$ 2/3)O$_3$ -0.45PbTiO$_3$ -0.45PbZrO$_3$ ceramics were investigated aiming at acoustic transducer applications. The vibration characteristics for the laminated circular plate was analyzed for the various thickness and diameter of the piezoceramic layer and metal layer. Also, the acoustic characteristics for the geometrical form of case have been investigated. The design and fabrication method worked in this paper can be utilized in development of actuator and acoustic device. -
We studied about electrical, chemical and mechanical characteristics of XLPE by dicumyl peroxide(DCP) and trimethylolpropane triacrylate(TMPTA) content ratio. DCP content was changed from 1.0 to 2.Sphr increasing 0.5phr. TMPTA content was changed 0.5 to 1.5phr increasing 0.5phr. Thermal analysis (DSC) was carried out in order to observe tendency of Tg according to DCP and TMPTA content. Tensile strength was measured in order to observe mechanical strength. In experimental results, content DCP 2.0phr and TMPTA 1.0phr has highest breakdown strength. Content DCP 2.0phr and TMPTA 0.5phr has lowest dielectric constant. Tendency of Tg did not affected by DCP and TMPTA content. Breakdown strength and Specific inductive capacity was measured.
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In order to save the energy and to protest environmental conservation, a evaporation type of PTC heater was developed as a Part of replacement in automobile industry. The honeycomb type of PTC heater made by Texas Instrument draw a much attention for this purpose. Especially this paper will describe the general and characterize the typical electrical properties of PTC heater for the application of automobile in detail.
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Though L
$a_{1+x}$ S$r_{2-x}$ M$n_2$ $O_{7}$ n=2 R-P phases have been well known to have CMR effect, it was generally believed that n=1 phase was insulating. But recently monolayered perovskite$Ca_{2-x}$ L$n_{x}$ Mn$O_4$ phase has been reported to show magnetoresistance. In this study, layered perovskite$Ca_{2-x}$ L$n_{x}$ Mn$O_4$ (x=0, 0.5, Ln=Pr, Nd, Sm, Gd) phases were synthesized by solid state reaction and their structures were refined by Rietveld method. The space groups of$Ca_2$ Mn$O_4$ , N$d_{0.5}$ C$a_{1.5}$ Mn$O_4$ phases were refined as C2cb and Fmmm, respectively.y.ely.y.y.y.y.y.y. -
The characterization of Zinc diffusion processes applied fur high-speed avalanche photodiodes has been examined. The different diffusion process conditions for InP test structures were explored. The Zinc diffusion profiles, such as the diffusion depth and the Zinc dopant concentration, were examined using secondary ion mass spectrometry with varying the process variables and material parameters. It is observed that the diffusion profiles are severely impacted on the process parameters, such as the amount of Zn
$_3$ P$_2$ source and the diffusion time, as well as material parameters, such as doping concentration of diffusion layer. These results can be utilized for the high-speed avalanche photodiode fabrication. -
This paper shows experimentally that oxide layer on the p-type Si-substrate can grow at low temperature(500
$^{\circ}C$ ∼600$^{\circ}C$ ) using high pressure water vapor system. As the result of experiment, oxide layer growth rate is about 0.19${\AA}$ /min at 500$^{\circ}C$ , 0.43${\AA}$ /min at 550$^{\circ}C$ , 1.2${\AA}$ /min at 600$^{\circ}C$ respectively. So, we know oxide layer growth follows reaction-controlled mechanism in given temperature range. Consequently, granting that oxide layer growth rate increases linearly to temperature over 600$^{\circ}C$ , we can expect oxide growth rate is 5.2${\AA}$ /min at 1000$^{\circ}C$ . High pressure oxidation of silicon is particularly attractive for the thick oxidation of power MOSFET, because thermal oxide layers can grow at relatively low temperature in run times comparable to typical high-temperature, 1 atm conditions. For higher-temperature, high-pressure oxidation, the oxidation time is reduced significantly -
Nanostructured ZnS thin films were grown on the slide glass substrate by the chemical bath deposition using an aqueous so1ution Of ZnSO
$_4$ and CH$_3$ CSNH$_2$ at 95$^{\circ}C$ . The average grain sizes of the ZnS thin film estimating from the Debye-Scherrer formula are 4.8 nm. The optical transmittance edge of the ZnS thin films (4.0 eV) was shifted to the shelter wavelength compared with that of the bulk ZnS (3.67 eV) due to the quantum size effects. The ZnS thin films showed a strong photoluminescence intensity and a sharp emission band from 410 to 480 nm 3t room temperature. The PWHM of photoluminescence peak was about 40 nm. For the viloet(410 nm) and blue(480 nm) emission of the ZnS thin films, the temperature dependence can be described by an Arrhenius equation with an activation energy of 168 and 157 meV, respectively. -
Metal-ferroelectric-insulator-semiconductor(MFIS) devices using Pt/
$LiNbO_3$ /Si structure were successfully fabricated. The dielectric constant of the AIN film calculated from the capacitance in the accumulation region in the capacitance-voltage(C-V) curve was about 8.2. The gate leakage current density of MIS devices using a aluminum electrode showed the least value of 1$\times$ $1O^{-8}$ A/$cm^2$ order at the electric field of 500kV/cm. The dielectric constant of$LiNbO_3$ film on AIN/Si structure was about 23 derived from 1MHz capacitance-voltage (C-V) measurement and the resistivity of the film at the field of 500kV/cm was about 5.6$\times$ $1O^{13}$ $\Omega$ .cm. -
In this work, we investigated the dependence of optical and electrical properties of amorphous hydrogenated SiC (a-SiC:H) films on annealing temperature(T
$\sub$ a/). The a-SiC:H films were deposited by PECVD(plasma enhanced vapor deposition) on coming glass, p-type Si(100) wafer using SiH$_4$ +CH$_4$ +N$_2$ gas mixture. The experimental results have shown that the optical energy band gap(E$\sub$ g/) of the a-SiC thin films unchanged in the range of T$\sub$ a/ from 400$^{\circ}C$ to 600$^{\circ}C$ . The Raman spectrum of the thin films, annealed at high temperatures, has shown that graphitization of carbon clusters and micro-crystalline silicon occurs. The current-voltage characteristics have shown good electrical properties at the annealed films. -
When charge-trap SONOS cells are used flash memory, the tunneling program/erase condition to minimize the generation of interface traps was investigated. SONOSFET NVSM cells were fabricated using 0.35
$\mu\textrm{m}$ standard memory cell embedded logic process including the ONO cell process. based on retrograde twin-well, single-poly, single metal CMOS process. The thickness of ONO triple-dielectric for memory cell is tunnel oxide of 24${\AA}$ , nitride of 74${\AA}$ , blocking oxide of 25${\AA}$ , respectively. The program mode(Vg: 7,8,9 V, Vs/Vd: -3 V, Vb: floating) and the erase mode(Vg: -4,-5,-6 V, Vs/Vd: floating, Vb: 3V) by modified Fowler-Nordheim(MFN) tunneling were used. The proposed programming condition for the flash memory of SONOSFET NVSM cells showed less degradation($\Delta$ Vth, S, Gm) characteristics than channel MFN tunneling operation. Also the program inhibit conditions of unselected cell for separated source lines NOR-tyupe flash memory application were investigated. we demonstrated that the program disturb phenomenon did not occur at source/drain voltage of 1 V∼4 V and gate voltage of 0 V∼4. -
YMnO
$_3$ films have been deposited with different Rf powers of 60W, 80W, 100W, and 120W. The structural properties of YMnO$_3$ films on Si(100) were analysed by XRD(X-ray diffraction). The c-axis oriented peaks of YMnO$_3$ were observed deposited in YMnO$_3$ /Si(100) structure of RF power at 87$0^{\circ}C$ in oxygen ambient, and the peaks were enlarged by increasing The RF powers. The dielectric constant of the film deposited at 100W and 120W of RF power were about 19, 20 respectively. -
Present transistors which have vertical structure show increased parasitic capacitance characteristics in accordance with the increase of non-active base area and collector area, consequently have disadvantage for high speed switching performance. In this paper, a horizontal structure transistor which has minimized parasitic capacitance in virtue of SDB(Silicon Direct Bonding) wafer and oxide sidewall isolation utilizing silicon trench technology is presented. Its structural characteristics were designed by ATHENA(SUPREM4), the process simulator from SILVACO International, and its performance was proven by ATLAS, the device simulator from SILVACO International. The performance of the proposed horizontal structure transistor was certified through the VCE-lC characteristics curve,
$h_{FE}$ -IC characteristics, and GP-plot. -
In this paper, stator form-winding sample coils based on silicone resin and polyimide were made for fault prediction and reliability estimation on the 200 Class insulation system of traction motors. The complex accelerative degradation was performed by periods during 10 cycles, which was composed of thermal stress, fast rising surge voltage, vibration, water immersion and overvoltage applying. After aging of 10 cycles, condition diagnosis test such as insulation resistance & polarization index, capacitance & dielectric loss and partial discharge properties were investigated in the temperature range of 20∼160
$^{\circ}C$ . Relationship among condition diagnosis test was analyzed to find an dominative degradation factor and an insulation state at end-life point. -
This study was investigated for searching a cause of flashover failure of polymer insulator and preparing countermeasures. Hydrophobicity, microstructure and chemical structural change of polymer weathershed were studied by polymer characterization methods. In addition, the electrical properties such as power frequency dry flashover voltage/impulse voltage tests, contamination characteristics were carried out. The hydrophobicity of polymer weathershed was decreased significantly and cracks were observed on the surface. Also, the electrical characteristics did not satisfy the KEPCO specification. The failed polymer insulators showed the more leakage current than 4 years service-aged ones. From the result, it can be concluded that the flashover failure of polymer insulator was attributed to the surface aging and severe contamination.
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Recently, complex insulation method is used in insulation system for underground power delivery devices. Considering the interfaces which affect stability of insulation system, By modeling interface between Epoxy and Rubber, AC interfacial breakdown properties with variation of many conditions to influence on electrical properties were investigated. In this paper, toughened Epoxy and Silicone rubber were used for materials to make interface .
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In this paper, the life-time of macro interface between Epoxy/EPDM which consists in underground power cable joints is predicted. The electrode system of specimen is designed by FEM(finite elements method). The breakdown strength of specimens are observed by applying high AC voltage at the room temperature. The breakdown times under the constant voltage below the breakdown voltage were gained. As constant voltage is applied, the breakdown time is proportion to the breakdown strength. The life exponent n is gained by inverse power law, and the long breakdown life time can be evaluated.
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Silicone rubbers are first silicone polymers and has named silicone from existence of Si-O bond similar to Keton. Silicon in organic compound has been called silicone, and linear or network polymers. Silicone rubbers have been used as an power insulator because they are well weather proof, ozone proof and have excellent electric characteristics, thermal stability, cold resistance and low surface energy. Especially, it is known that they have very excellent characteristics at 200[
$^{\circ}C$ ]. For this study, we made silicone rubbers as specimens and we measured dielectric loss tangent due to applied voltage at temperature range 25[$^{\circ}C$ ] to 180[$^{\circ}C$ ] and frequency range 20[Hz] to 1${\times}$ 10$\^$ 6/[Hz] to examine dielectric properties. We measured dielectric loss tangent to study the insulation performance of silicone rubbers. -
In this paper, physical properties and dielectric characteristics of LLDPE and EVA which are used as a blending material to improve PE's performance are studied. LLDPE of 0.92[g/cm3] and EVA with the EVA contents of 12.5[%1 were selected as specimens, and X-ray diffraction(XRD) are used to analysis physical properties. We measured dielectric constant with the frequency range from 20[Hz] to 1 [MHz], applied voltage 6[V] and the temperature from 25[
$^{\circ}C$ ] to 110[$^{\circ}C$ ]. From XRD, LLDPE has a crystallinity of 53[%] and, 46[%] for EVA. LLDPE has as low tan$\delta$ as of 10$^{-3}$ ~10$^{-4}$ and inflection point near 500[Hz]. At frequency region lower than 500[Hz], tan$\delta$ decreases with frequency and increases with temperature and it is considered to be caused by conductive carriers within specimen. Over 500[Hz], it is the reverse and we thought that it was caused by decrease of relaxation time due to Debye theory, EVA has tan$\delta$ with the values of 10$^{-2}$ ~10$^{-3}$ , which is higher than that of LLDPE, and it has inflection point at 60[Hz]. It is shown that Dielectric characteristics of EVA are similar to LLDPE's. -
High temperature superconducting YBCO films have been grown on MgO substrates by pulsed laser deposition (PLD) with Nd:YAG laser Superconducting microwave filter was fabricated by conventional photolithography method. We have designed filter with the center frequency of 14 GHz. We have measured the center frequency of filter at 77 K and its critical temperature 89K. Also we have designed another filter to compare frequency responses. The measured frequency responses will be presented.
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We have fabricated good quality superconducting YBa
$_2$ Cu$_3$ $O_{7-x}$ (YBCO) thin films on Hastelloy(Ni-Cr-Mo alloys) metallic substrates with CeO$_2$ and BaTiO$_3$ buffer layers in-situ by pulsed laser deposition in a multi-target processing chamber. YBCO film with CeO$_2$ single buffer layer shows T$_{c}$ of 71.64 K and the grain size less than 0.1${\mu}{\textrm}{m}$ . When BaTiO$_3$ is used as a single buffer layer, the grain size of YBCO is observed to be larger than that of YBCO/CeO$_2$ by 200 times and the transition temperature of the film is enhanced to be about 84 K. CeO$_2$ /BaTiO$_3$ double buffer layer has been adopted to enhance the superconducting properties, which results in the enhancement of the critical temperature and the critical current density to be about 85 K and 8.4$\times$ 10$^4$ A/cm$^2$ at 77 K, respectively mainly due to the enlargement of the grain size of YBCO film.ilm. -
The fabrication of high quality superconducting thin films using pulsed laser deposition (PLD) has been reported to find optimized processing conditions and to make the millimeter-wave devices. High temperature superconducting (HTS) YBCO films were prepared on MgO (10
${\times}$ 10${\times}$ 0.5mm) substrates by the PLD. The 3 pole bandpass filter with the center frequency of 22 GHz for satellite communication was designed consisting of hairpin coupled-lines to reduce the configuration in size. YBCO films are c-axis oriented and show superconductive transition temperatures of 88∼89 K with the transition widths < 0.5 K. The insertion loss of passband at 70 K was about 5 dB. The measured frequency response of superconducting filter will be compared with the simulation result. -
For the performance enhancement of communication system, high quality filters are required. Also a minimization of size of filter is required for the interation of devices in the limited area. Conventional metal filters made of copper can be substituted by high quality high temperature superconducting(HTS) films for better performance. Hairpin type filters have been designed with the center frequency 14 GHz for the size reduction. 3-pole and 4-pole filters centered at 14 GHz with the bandwidth of about 300 MHz were designed and fabricated. With the simulation results, the frequency responses showed low insertion loss and sharp skirts characteristics. The frequency response of HTS 14 GHz fi1ter was measured at 77 K and compared with the simulation results. We have compared YBCO filters and copper filters which were made with the same design rules. Simulated and measured frequency responses reveal that HTS YBCO hairpin type bandpass filters show better performance than copper filters.
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Anistropic [Ta/NdFeB/Ta] thin film was sputtered on heated Si substrate by Nd
$\_$ 17/Fe$\_$ 74/B$\_$ 9/ target. The grain size of the films increased according to the increase of substrate temperature, and the film deposited at 650$^{\circ}C$ showed optimum coercivity. 4$\pi$ M$\_$ r/,$\_$ i/H$\_$ c/ and (BH)$\_$ max/ measured perpendicular to the film plane of thin film deposited at 650$^{\circ}C$ are 12.3 kG, 9.9 kOe and 37 MGOe, respectivly. -
A key technology for achieving commercial Nb
$_3$ Sn superconducting wires may be driven from fabrication Process of big-scale billets. Sub-element billet with diameter of 200 mm was designed and fabricated. This billet was hot-extruded and drawn. Cu stabilizer tube, Nb barrier tube and 19 sub-elements inserted Sn core were composed for strand. There was no breakage in the strand that was constituted with annealed sub-element. It was need that billet had to treat HIP because of remove of voids and goad contact between Cu and Nb filaments. Ta wound sheet was better than Ta tube thor barrier in the strand. Ic of the Nb$_3$ Sn wire at 127, 4.2K was over than 120 A. -
In this study, we fabricated Bi-2223/Ag high temperature superconducting tapes using PIT (Powder-In-Tube) process to apply the superconducting magnet, cable and etc. It's inevitable to deform the superconducting tapes with axial strain for application. Therefore, for the characterization of the strain sensitivity of the superconducting properties, the degradation of Bi-2223/Ag tapes due to axial strain were investigated by measuring the critical current as a function of applied tension strain and external magnetic field. The critical current of Bi-2223/Ag tapes were decreased slightly up to 0.3∼0.4% applied strain but, drastically decreased more than these strains. Superconducting filament cores consisted of brittle ceramic fibers were broken easily by the large strain and current path were decreased simultaneously.
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The progress in the field of electronic materials has been especially significant for applications involving a range of electrical properties. Its importance is increasing with the increasing demand for integrated circuits. The sol-gel technique has been used for many years, and the metal alkoxides have featured prominently as source materials. The method consist of making a homogeneous solution of the component metal alkoxides in a suitable solvent, usually the parent alcohol; and then causing the hydrolysis under controlled conditions to produce a gel containing the hydrated metal oxide. The gel is then dried, and fired to produce a ceramic or glassy material at a temperature much lower than that required by the conventional melting process. This project consists of important theoretical considerations, processing techniques and applications related to electrophoresis derived thin films. In the electrophoretic process a metal alkoxide solution is gelled through hydrolysis-polymerization and converted the gel thin layer to an oxide by heating at relatively low temperatures.
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In this study, we have investigated the holography recording and reconstruction of the polarization state in chalcogenide
$As_{40}$ $Ge_{10}$ $Se_{15}$ $S_{35}$ thin films using a He-Ne laser light(633nm). The thickness of thin films is a 8677${\AA}$ and 9093${\AA}$ . A He-Ne laser used to probe and record of the grating. Also the, polarization state of object beam modulated with a$\lambda/4$ wave plate. The polarization state of the +1st order diffracted beam generated by readout of the grating with a linearly polarized reference beam. It was the same-handed polarization state as the polarization state of the recording beam. The diffraction efficiency of circularly polarized recording represented higher than other polarization state. -
Fabrication of InP-based photonic devices by dry etch Process is important for clear formation of waveguide mesa structure. We have developed more efficient etch process of the inductively coupled plasma (ICP) with low damages and less polymeric deposits for the InP-based photonic devices than the reactive ion etching (RIE) technique. We report the tendency of etch rate variation by the process parameters of the RF power, pressure, gas flow rate, and the gas mixing ratio. The surface roughness of InP-based waveguide structure was more improved by the light wet etching in the mixed solution of H
$_2$ SO$_4$ :H$_2$ O (1:1) -
Various substrates were compared for the investigation of the optical properties of ZnO thin films. ZnO thin films have been deposited on (100) p-type silicon substrates and (001) sapphire substrates by pulsed laser deposition technique using a Nd:YAG laser with the wavelength of 355 nm. Oxygen and nitrogen gases were used as ambient gases. Substrate temperatures were varied in the range of 200
$^{\circ}C$ to 600$^{\circ}C$ at a fixed ambient gas pressure of 350 mTorr. ZnO films have been deposited on various substrates, such as Si and sapphire wafers. We have investigated substrate effect on the optical and structural properties of ZnO thin films using X-ray diffraction (XRD) and photoluminescence (PL). -
Characteristics of organic light-emitting diodes(OLEDs) were studied with devices made by PECCP[poly(3,6-N-2-ethylhexyl carbazolyl cyanoterephthalidene)] Langmuir-Blodget(LB) films. The emissive organic material was synthesized and named PECCP, which has a strong electron donor group and an electron accepter group in main chain repeated unit. The LB technique was employed to investigate the identification of the recombination zone in the ITO/PECCP LB films/Alq
$_3$ /Al structure by varying the LB film thickness. PECCP was considered as an emissive layer and Alq$_3$ was used as an electron-transport layer. We measured current-voltage(I-V) characteristics, UV/visible absorption, PL spectrum, and EL spectrum of those devises. -
A new photo-alignment material, copoly (PM4Ch-ChMA), copoly (poly (4-methacryloyloxy) chalcone-cholesterol methacrylate) was synthesized and the electro-optical (EO) characteristics for the photo-aligned vertical-aligned (VA)-LC display (LCD) were studied. Good voltage-transmittance (V-T) and response time characteristics for the photo-aligned VA-LCD with polarized UV exposure on the copolymer-1 (2%) surfaces for 1 min. were observed. EO performance for the photo-aligned VA-LCD decreased with increasing UV exposure time on a copolymer surface. Also, excellent V-T and response time characteristics for the photo-aligned VA-LCD with UV exposure on copolymer-2 and copolymer-3 surfaces for 3min. can be achieved.
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The mechanical and electrical properties of the hot-pressed and annealed
$\beta$ -SiC-ZrB$_2$ electroconductive ceramic composites were investigated as function of the liquid forming additives of$Al_2$ O$_3$ +Y$_2$ O$_3$ . Phase analysis of composites by XRD revelled$\alpha$ -SiC(6H), ZrB$_2$ , and YAG(Al$_{5}$ Y$_3$ O$_{12}$ ). Owing to crack deflection, crack bridging, phase transition and YAG of fracture toughness mechanism, the fracture toughness showed the highest value of 6.3MPa.m$^{1}$ 2/ for composites added with 24wt%$Al_2$ O$_3$ +Y$_2$ O$_3$ additives at room temperature. The resistance temperature coefficient respectively showed the value of 2.46$\times$ 10$^{-3}$ , 2.47$\times$ 10$^{-3}$ , 2.52$\times$ 10$^{-3}$ $^{\circ}C$ for composite added with 16, 20, 24wt% A1$_2$ O$_3$ +Y$_2$ O$_3$ additives. The electircal resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature range of$25^{\circ}C$ to 90$0^{\circ}C$ . -
The (1-x)MgTiO
$_3$ -xSrTiO$_3$ (x=0.02∼0.08) ceramics were fabricated by conventional mixed oxide method. The sintering temperature and time were 1250$^{\circ}C$ ∼1400$^{\circ}C$ , 2hr., respectively. The structural and microwave dielectric properties were investigated by varying sintering temperature and composition ratio. In the (1-x)MgTiO$_3$ -xSrTiO$_3$ (x=0.02) ceramics, the cubic SrTiO$_3$ and hexagonal MgTiO$_3$ phases were coexisted. The dielectric constant was increased and the temperature coefficient of resonant frequency($\tau_f$ ) was decreased with addition of SrTiO$_3$ . The temperature coefficient of resonant frequency($\tau_f$ ) was gradually varied from negative value to positive value with increasing the SrTiO$_3$ . -
In this study, contour-vibration-mode Pb(
$Ni_{1/2}$ ,$W_{1/2}$ )$O_3$ -Pb(Zr,Ti)$O_3$ piezoelectric transformers for driving a 28W(T5) fluorescent lamp were fabricated to the modified filter structure with ring and dot electrodes which has been developed for application in 455kHz AM radios. The piezoelectric transformers were fabricated to the size of$31.5 $\times$ 31.5$\times$ 2.5$mm^3$ with the variations of ring/dot electrode area ratio. Driving of piezoelectric transformer was carried out with input region for the ring electrode and output region for the dot electrode. The electrical properties and characteristic temperature rises caused by the vibration were measured at various load resistances. A 28 W fluorescent lamp, T5, was successfully driven by the fabricated transformer. The transformer with ring/dot electrode area ratio of 1.83 exhibited the best properties in terms of output power, efficiency and characteristic temperature rise, 30.95 W, 97.57% and8.3$^{\circ}C$ respectively. -
In this paper, we investigated the output power, step-up ratio and efficiency properties of piezoelectric transformer with dielectric and piezoelectric characteristics of manufactured ceramics. The piezoelectric transformers with
$2.0 $\times$ 10$\times$ 48[$mm^3$ ] size were fabricated and its electrical properties were measured. When output power of 6W was constantly maintained, T2 piezoelectric transformer showed the minimum temperature rise of$9(^{\circ}C)$ at$150(K\Omega)$ load resistance. However, T1 piezoelecric transformer showed the temperature rise of$7.2(^{\circ}C)$ at$200(K\Omega)$ load resistance. The 6[w] CCFL (Cold Cathode Fluorescent Lamp) was successfully driven by T1 and T2 piezoelectric transformer but, its temperature rise$\Delta$ T[$^{\circ}C)$ ] was generated more than$20(^{\circ}C)$ . It is concluded that we have to design the piezoelectric transformers so that its output impedance correspond to the load impeadance, including any stray capacitance. -
The objective of this paper is to demonstrate degradation phenomena through DC degradation tests and predicts degradation phenomena as a function of time from the tests. The ZnO varistor used in this investigation were fabricated by standard ceramic techniques. Especial, these were sintered in nitrogen atmosphere, at 2 h, for
$1300^{\circ}C$ . The conditions of DC degradation test were 115$\pm$ $2^{\circ}C$ for 0, 2, 4, and 8 h, respectively. To demonstrate the degradation phenomena of ZnO varistors, Voltagecurrent analyses were performed before and after the degradation test, and frequency analyses were used with the time of the degradation tests. It was found that the degradation occurred in not grain but grain boundary and the degradation behavior of varistors was unsymmetrically degraded with the direction of tests. -
Ferroelectric thin film capacitors with high dielectric constant are important for the application of memory devices. In this work, thin films of PLT(28)(Pb
$\sub$ 0.72/La$\sub$ 0.28/Ti$\sub$ 0.93/O$_3$ ) were fabricated on Pt/Ti/SiO$_2$ /Si substrates in-situ annealing and ex-situ annealing have been compared depending on the annealing time. We have systematically investigated the variation of grain sizes depending on the condition of post-annealing and the variation of deposition rate. C-V measurement, ferroelectric properties, leakage current and SEM were performed to investigate the electrical properties and the microstructural properties of Pb(La,Ti)O$_3$ . -
It was examined that the relationship between microstructures, electrical properties and crystal structure of (1-x)CaMnO
$_3$ -xCaTiO$_3$ solid solution system which was made by mixing a semiconducting material CaMnO$_3$ of low resistance and a dielectric material CaTiO$_3$ of high resistance with variable ratios (x=0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0). As the CaTiO$_3$ increased, the resistance, B constant and lattice constant were increased, but the grain size was decreased. On particular, above 50wt% of CaTiO$_3$ , the resistance at 2 5$^{\circ}C$ was rapidly increased due to the correlation in connectivity of the lattices between the conductive Mn$^{+4}$ octahedron and the insulative Ti$^{+4}$ octahedron.ron. -
The aim of present work was to fabricate the piezoelectric composite materials of low megahertz applications such as non-destructive testing of materials. Among all the various composites, those with PZT rods embedded in Spurrs epoxy with regular periodicity (1-3 connectivity) was fabricated by dice and fill method. The fabricated size of the PZT cell were 0.18X0.18, 0.28X0.28mm
$^2$ , respectively. And the volume ratio of the PZT cell were 52, 64%, respectively. The resonant frequency and anti-resonant frequency of the composites were 3.5 MHz and 4.3MHz, respectively. The piezoelectric coupling coefficient were about 38 and 37% and the mechanical quality factor were about 12.7 and 22. These value were very different from these of bulk PZT Plate. -
Characteristics of piezoelectric thick films prepared by screen printing method were investigated. The piezoelectric thick films were printed using Pb(Mg,Nb)O
$_3$ -Pb(Zr,Ti)O$_3$ system. The lower electrodes were coated with various thickness of Ag-Pd by screen printing to investigate the effect as a diffusion barrier and deposited with Pt by sputtering on Ag-Pd. The ceramic paste was prepared by mixing powder and binder with various ratios using three roll miller. The fabricated thick films were burned out at 650$^{\circ}C$ and sintered at 950$^{\circ}C$ in the O$_2$ condition for each 20, 60min after printing with 350mesh screen. The thickness of piezoelectric thick film was 15∼20$\mu\textrm{m}$ and the Ag-Pd electrode acted as a diffusion barrier above 3$\mu\textrm{m}$ thickness. When the lower electrode Ag-Pd was 6$\mu\textrm{m}$ and the piezoelectric thick films were sintered by 2nd step (650$^{\circ}C$ /20min and 950$^{\circ}C$ /1h) using paste mixed Pb(Mg,Nb)O$_3$ -Pb(Zr,Ti)O$_3$ $.$ MnO$_2$ + Bi$_2$ O$_3$ . V$_2$ O$\_$ 5/ and binder in the ratio of 70:30, the remnant polarization of thick film was 9.1${\mu}$ C /cm$^2$ . -
The length extensional vibration mode of a piezoelectric ceramic substrate is used in fabricating the ultra-small size resonators and filters. In general, the three side ratios of the substrate effect the resonant characteristics of the resonator using its length extensional vibration. In this paper, their relationships are studied. We know that changing the ratio of its length to its width makes possible to change the resonant frequency of the width vibration without degrading the length extensional vibration.
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Recently mobile communication fields need piezoelectric ceramic resonators and filters as possible as small. The length-extensional vibration mode of a rectangular piezoelectric cesamic plate has the advantage of the small size, but the mode has not been studied sufficiently because it was not used extensively until now. In this paper, PZT + x[wt%l
$Cr_20_3$ ceramics with rhombohedra1 phase were fabricated. And temperature stability for the mode of the ceramic specimen was investigated. Contrary to our expectations, addition of the stabilizer,$Cr_20_3$ did not promote the temperature stability for the mode in the PZT ceramic specimen with rhombohedra1 phase. -
The effects of deposition temperature and post annealing process of ferroelectric PbZr
$\sub$ 0.52/Ti$\sub$ 0.48/O$_3$ (PZT) thin films by pulsed laser deposition (PLD) were investigated. The PZT thin films were deposited at 400, 450, 500, and 550$^{\circ}C$ , with/without post annealing at 650$^{\circ}C$ for 30 min. The PZT thin films deposited above 500$^{\circ}C$ without post annealing were crystallized into peroveskite phase, but the PZT thin films deposited below 450$^{\circ}C$ had pyrochlore phase. The PZT thin films deposited below 450$^{\circ}C$ with post annealing also crystallized into pure perovskite. Compared to the PZT thin films which were deposited at 450$^{\circ}C$ and post annealed, the films deposited at 550$^{\circ}C$ have a columnar microstructure and high remnant polarization 28 (${\mu}$ C/cm$^2$ ). With in-situ annealing at oxygen ambient, the PZT thin films reduced oxygen vacancies and increased retained polarization. -
We have investigated the Pt doping effect on structural and electrochemical properties of amorphous vanadium oxide film, grown by radio frequency magnetron sputtering. Room temperature charge-discharge measurements based on a half-cell with a constant current clearly indicated that the Pt doping could improve the cyclibility of V
$_2$ O$_{5}$ cathode film. Using glancing angle x-ray diffraction (GXRD) and high resolution transmission electron microscopy (HRTEM) analysis, we found that the Pt doping with l0W r.f. power induce more random amorphous structure than undoped V$_2$ O$_{5}$ film. As the r.f. power of Pt increases, large amount of Pt incorporates into amorphous V$_2$ O$_{5}$ and makes PtOx microcrystalline phase in amorphous matrix. This result suggests that the semicondcuting PtOx microcrystalline phase in amorphous matrix lead to a drastically faded cyclibility of 50W Pt doped V$_2$ O$_{5}$ cathode film. Possible explanations are given to describe the Pt doping effect on cyclibility of vanadium oxide cathode film.de film. -
The SrBi
$_2$ Ta$_2$ O$\sub$ 9/(SBT) thin films are deposited on Pt-coated electrode(Pt/TiO$_2$ /SiO$_2$ /Si) using RF sputtering method. The SBT thin films deposited on substrate at 400-500[$^{\circ}C$ ]. SBT thin film deposited on Pt-coated electrodes have the cubic perovskite structure and polycrystalline state. With increasing annealing temperature from 600[$^{\circ}C$ ] to 850[$^{\circ}C$ ], flourite Phase was crystalized to 650[$^{\circ}C$ ] and Bi-layered perovskite phase was crystalized above 700[$^{\circ}C$ ]. The maximum remanent polarization is 11.73${\mu}$ C/cm$^2$ at 500[$^{\circ}C$ ] of substrate temperature and 750[$^{\circ}C$ ] annealing temperature for 30min. -
Annealing dependencies of the fatigue properties of SrBi
$_2$ Ta$_2$ $O_{9}$ thin films were observed as function of substrate temperature(400-50$0^{\circ}C$ ) by the rf magnetron sputtering method. With increasing annealing temperature from$600^{\circ}C$ to 85$0^{\circ}C$ , flourite phase was crystalized to$650^{\circ}C$ and Bi-layered perovskite phase was crystalized above$700^{\circ}C$ . The fatigue characteristics of SBT thin films deposited on Pt/TiO$_2$ /SiO$_2$ /Si substrate did not change up to 101o switching cycles.s. -
In order to investigate the effect of deposition conditions on crystallographic properties of ZnO thin films by Facing Targets Sputtering system which can deposit thin films in plasma-free situation and change the deposition conditions in wide range. The characteristics of zinc oxide thin films on power, inter targets distance, and substrate temperature were investigated by XRD(x-ray diffractometer), alpha-step (Tencor) analyses. The excellently c-axis oriented zinc oxide thin films were obtained at sputter pressure 1mTorr, sputtering current 0.4A, substrate temperature 300
$^{\circ}C$ , inter target distance 100mm. In these conditions, the rocking curve of zinc oxide thin films deposited on Glass was 3.9$^{\circ}$ . -
The growth properties of diamond grain were examined by Raman spectroscopy and microscope images. Diamond thin films were prepared on single crystal Si wafers by microwave Plasma chemical vapor deposition. Preparation conditions, substrate temperature, boron concentration and deposition time were controlled differently. Prepared diamond thin films have different surface morphology and grain size respectively Diamond grain size was gradually changed by substrate temperature. The biggest diamond grain size was observed in the substrate, which has highest temperature. The diamond grain size by boron concentration was slightly changed but morphology of diamond grain became amorphous according to increasing of boron concentration. Time was also needed to be a big diamond grain. However, time was not a main factor for being a big diamond grain. Raman spectra of diamond film, which was deposited at high substrate temperature, showed sharp peaks at 1334
$cm^{-1}$ / and these were characteristics of crystalline diamond. A broad peak centered at 1550$cm^{-1}$ /, corresponding to non-diamond component (sp$^2$ carbon), could be observed in the substrate, which has low temperature. -
We synthesized polypyrrole (PPy) nanotubules by oxidative polymerization of the pyrrole monomer within the pores of a polycarbonate template. The electrochemical behavior was investigated using cyclic voltammetry. The redox potential was about -0.5 V vs. Ag/AgCl reference electrode, while the potential was about 0 V for PPy film. It is considered as the backbone grows according to the pore wall. Therefore, it is possible to be arranged regularly. That leads to improvement in the electron hopping. By electrochemical doping of glucose oxidase (GOx) on PPy nanotubules, an enzyme electrode has been fabricated. The kinetic parameter of biochemical reaction with glucose was evaluated. The formal Michaelis constant and maximum current calculated by computer were about 11.4 mmol
$dm^3$ and 170.85 A respectively. Obviously, an affinity for the substrate and current response of the PPy nanotubules enzyme electrode are rather good, comparing with that of PPy film. -
We give pressure stimulation into long chain fatty acid of LB thin films then manufacture a device under the accumulation condition that the state surface pressure is 20[mN/m]. In processing of a device manufacture, we can see the process is good from the change of a surface pressure for organic thin films and transfer ratio of area per molecule. The structure of manufactured device is Au/Arachidic acid/Al, the number of accumulated layers are 13, 17 and 19. The I-V characteristic of the device is measured from 0[V] to +1.5[V]. We have investigated the capacitance because this fatty acid system have a accumulated layers. The maximum value of measured current is increased as the number of accumulated layers are decreased. The capacitor properties of a thin film is better as the distance between electrodes is smaller. The results have shown the insulating materials and could control the conductivity by accumulated layers.
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A great deal of research has been done in the field of characterization for piezoelectric thin films after the first report on the measurement for the piezoelectric coefficient of thin films in 1990. The main idea of this research is to provide a distinctive solution for the measurement of both the longitudinal and the transverse piezoelectric d-coefficients, d
$\sub$ 33/ and d$\sub$ 3l/, of ferroelectric thin films and also thick films. In general, to get these two coefficients of thin films, two different measuring systems are required. Here, we propose the improved method for the evaluation of these two coefficients with single equipment and with the relatively convenient procedure. The two-step loading process of applying the both positive and the negative pressure has been designed to acquire the piezoelectric coefficients. These results have beer calibrated for both the longitudinal and the transverse piezoelectric d-coefficients, d$\sub$ 33/ and d$\sub$ 31/, of thin films. In the first stage of the experiments, we have obtained d$\sub$ 33/ of 108pC/N and d$\sub$ 31/ of 57pC/N for the PZT thin films. -
All solid-state thin film supercapacitor(TFSC) based on
$RuO_2$ electrode was fabricated. Ruthenium oxide$(RuO_2)$ thin film was deposited on Pt/Ti/Si subsrate by d.c. magnetron sputtering. LiPON(lithium phosphorus oxynitride) thin film were deposited by r.f. reactive sputtering. X-ray diffraction patterns of$RuO_2$ and LiPON films revealed that crystal structures of both films were amorphous. To decrease resistivity of$RuO_2$ thin film,$RuO_2$ thin film was deposited with$H_2O$ vapor. In order to decide the maximum ionic conductivity, the LiPON films were prepared by various sputtering condition. The maximum ionic conductivity was$9.5\times{10}^7S/cm$ . A charge-discharge measurements showed the capacity of$3\times{10-2}\;F/cm^2-\mu{m}$ for the as-fabricated TFSC. The discharging efficiency was decreased after 500 cycles by 40 %. -
The nitrogen oxides, NO and NO2, abbreviated usually as NOx, emitted from combustion facilities such as power plants and automobiles are the topical 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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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)CO3 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 results, the performance of Ni-YSZ anode(40vo1%) was better excellent than the others. -
To understand the behavior of electron, ions and radicals on radio-frequency non-equilibrium plasma, it is necessary to know the basic information about its fundamental properties and reactions. Especially, the transient response of radio-frequency plasma has an important means of controlling selective etch rates and investigating the stability of a plasma chemical process. In this paper, we present the results of periodic steady-state behavior and transient behavior carbon Tetrafluoride(CF
$_4$ ) discharge at 0.2 Torr in a 2 cm gap parallel-plate. After the number densities of charged particles became steady-state, the applied voltage was increased or decreased in an instant and the transient behavior of charged particles and radicals was investigated from one steady-state to the next steady state. -
We measured the electron transport coefficients, the electron drift velocity W and the longitudinal diffusion coefficient
$D_{L}$ in the 0.526% and 5.05%$C_{3}F_{8}$ -Ar mixtures over the E/N range from 0.01 Td to 100 Td by the double shutter drift tube, and compared the measured results by Hunter et al. with those. We determined the inelastic collision cross sections for the$C_{3}F_{8}$ molecule by the comparison of the present measurements and the calculation of electron transport coefficients in the$C_{3}F_{8}$ -Ar mixtures by using a multi-term Boltzmann equation analysis. -
SrBi
$_2$ Ta$_2$ $O_{9}$ (SBT) thin films were etched in Ar/SF$_{6}$ and Ar/CHF$_3$ gas plasma using magnetically enhanced inductively coupled plasma(MEICP) system. The etch rates of SBT thin film were 1500$\AA$ /min in SF$_{6}$ /Ar and 1650$\AA$ /min in Ar/CHF$_3$ at a rf power of 600W a dc-bias voltage of -l50V. a chamber pressure of 10 mTorr. In order to examine the chemical reactions on the etched SBT thin film surface , x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were examined. In etching SBT thin film with F-base gas plasma, M(Sr. Bi. Ta)-O bonds are broken by Ar ion bombardment and form SrFand TaF$_2$ by chemical reaction with F. SrF and TaF$_2$ are removed more easily by Ar ion bombardmentrdment -
Recently, electret applications have placed the focus on polymer thin film because electrical properties of a blend are studied. In this paper, we hale measured the infra sonic frequency by using Electret Sensor. Electret is formed by appling the voltage range of -4[kV] to -8[kV] to PTFE film and the sensor is manufactured by moment method to detect the infra-sonic signal. Electret Infrasonic Transducer, which is designed and manufactured by using of the moment method according to the potential and electric field simulation , shows its promising result, since the average rising rate of sensitivity is 7.68 [dB/oct] under 1[Hz], and the average values are within
${\pm}$ 1 [dB/oct]. As a result, it is believed that the characteristics of acquired transducer can be applied to the medical treatment, the industry, and the animal life researches, and also the study on noise elimination is required. -
Amorphous MnO
$_2$ $.$ nH$_2$ O in 1M KOH aqueous electrolyte proves to be an excellent electrode for a faradic electrochemical capacitor cycled between -0.5 and +1.0 versus Ag/AgCl. In order to observe morphology and crystalline structure of MnO$_2$ powder, we analyzed it by XRD and SEM. The effect of oxidation treatment on MnO$_2$ electrode was observed by different oxidation voltages. A maximum capacitance of 364F/g was obtained by 1.1V oxidation treatment. This capacitance was attributed solely to a surface redox mechanism -
Considering the effective distribution coefficient of Ni in Fe-Ni-Co invar alloy containing a little amount of carbon, we investigated on the thermal expansion coefficient(
${\alpha}$ ). Fe-Ni-Co invar alloy had a large thermal expansion coefficient in as-casted compared with solution treated. The thermal expansion coefficient of Fe-Ni-Co alloy increased with the carbon content in both state of as-casted and solution treated. The effective distribution coefficient(Ke$\^$ Ni/) of Ni was smaller than unity in alloy of not containing carbon, but is way larger than unity in alloy of containing carbon. It was considered that the homogeneity of Ni in primary austenite affected thermal expansion coefficient.