1997.07d
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The chief advantage of these NCI, from a handling viewpoint. was an up to 90% weight reduction over their porcelain counter. Diagnosis and the life expectancy of NCI for transmission lines depend on a number of factors, many of which are associated with natural tracking breakdown, while others are related to manufacturing conditions. Recently The importance of optimizing a NCI for good performance under a wide variety of test condition and diagnosis is emphasized ; as well as the increased importance of natural breakdown testing. Today, at transmission lines, NCI have become very popular at 154 through 345 kV.
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In this work, simultaneous measurement such as change distribution and electrical conduction of maleic anhydride grafted XLPE was investigated. Heterocharge was found in XLPE and it decreased with increasing MAR graft ratio in XLPE-g-MAH. Conduction currents also decreased with increasing MAR graft ratio. The relationship between the space change behavior and the electrical conduction characteristics in XLPE-g-MAH is discussed.
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22.9kV 지중 배전용 전력 케이블의 절연체를 평가하기 위한 방법으로서 제안하고자 한다. 케이블 절연체를 절연파괴시켜 얻어진 결과를 통계적으로 평가하고자 한다. 절연파괴 시험 시료로서 케이블의 내외도 반도전층을 갖는 절연체인 XLPE에 침전극을 삽입시켜 일정전압하에서 절연 파괴에 이르는 시간을 각각 측정하고, 2 모수 Weibull분포를 이용하여, 형과 척도의 모수를 각각 구하였다.
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In this paper we evaluated dielectric properties and temperature dependency in PET with and without semiconductor. Dielectric losses of PET without and with semiconductor was
$3.7{\times}10^{-3}$ (%) and$1.8{\times}10^{-3}$ (%), respectively, at room temperature. On the condition that semiconductors exist, we confirmed that dielectric properties had been influence on semiconductor's number. -
When the short fault current is flowed into a fuse, the notch of element is melted, and burnbacked by arc plasma, which caused by the voltage of fuse at both ends. The cutoff ability of fuse is heavily influenced by the degree of burnback. In this paper, we investigated the amount of burnback to the applied voltage di/dt variation, As a result, we confirmed that the amount of burnback is proportional to the variation of the applied voltage.
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This study describes the influence of the size of the median particles of alumina trihydrated(ATH) filler on the tracking resistance, tensile properties, dielectric properties and water immersion properties of EPDM rubber. A fixed 100pph concentration of the filler of A TH was used for all particle sizes from 0.7 to
$20{\mu}m$ . It is shown that tracking and erosion resistance decrease with increasing particle size, whereas tensile properties and dielectric properties are improved with increasing particle size of ATH. -
In order to investigate the electrical characteristics due to the BTA(Benzotriazole) additive in the transformer, the electrical characteristics of the transformer oils contained benzotriazole as an anti-static agent for streaming electrification is studied by measuring the electric conduction. As a result of the electrical conduction characteristics, it is confirmed that the conduction current of virgin specimen is more higher than that of specimen contained the BT A 10[ppm] over 35[
$^{\circ}C$ ], but that of specimen contained the BT A 10[ppm] over 50[$^{\circ}C$ ] is increased. -
Hydrolysis of BTDA-ODA: MPDA, PMDA-ODA, PIQ polyimides were investigated by FT-IR. The results showed that hydrolysis depends on structure of polyimide and that polyimide obtains hydrolytic stability by curing. Polyimide-aluminum interfaces were characterized by RAIR. It was concluded that imidization of the polyamic acid to polyimde was inhibited by interaction of acid groups with substrate to form aluminum carboxylate.
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Poly(1,4-phenylene(1-methoxyenthylene)), organic water soluble PPV precursor was synthesized for polymer electroluminescence(EL) device. To control the molecular array, deposition method of emitter was Langmuir-Blodgett(LB). PPV precursor layer was treated thermally to conversion of PPV. Optical, electrical and EL properties of PPV LB thin film was estimated. Homogeneous light emission of greenish-yellow in PPV LB thin film can be easily confirmed under normal lighting even at low driving voltage. Polymer EL device using PPV LB thin film as emitter materials had a possibility to apply to next generation display device.
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A gaseous oxygen detector has been developed in a configuration of Pd-
$SnO_x$ -$Si_3N_4$ -$SiO_2$ -Si-Al with highly resistive$SnO_x$ layer as the oxygen adsorptive element. In this paper, we present the characteristics of the device in response to oxygen adsoption/desorption under applied d.c. bias. Experimental results showed that the oxygen adsorptive response by the device was reduced significantly under a positive gate bias, for all experimental regions of$O_2$ partial pressure. On the other hand, the application of a negative gate bias increased the device's adsorptive response of oxgyen. A device model concerning this electroadsorption/desorption behavior of the device is provided. -
펄스 레이저 증착법을 이용하여 MgO 기판 위에 YBCO 박막을 c 축으로 성장시켰다. 이를 위하여 다양한 두께의 YBCO 박막을 여러 온도에서 증착시킴으로서 두께와 온도에 따른 YBCO 박막의 방향성을 조사하였다. 레이저원으로는 Nd:YAG 레이저의 355 nm의 파장을 이용하였으며, 증착시 기판온도는
$700^{\circ}C$ 와$750^{\circ}C$ 에서 박막의 두께를$3,000{\AA}$ ,$10,000{\AA}$ ,$20,000{\AA}$ 등으로 변화시켜 증착하였다. 이렇게 증착되어진 박막의 표면은 SEM으로 관촬되어졌으며, Raman Spectrascopy로 박막을 분석하였고, XRD를 사용하여 그 박막의 배향성을 연구하였다. 본 논문에서는 이와 같은 분석과 연구를 통하여 증착되어진 다성분 박막의 배향성이 기판온도와 박막두께에 따라 민감하게 변화함을 체계적으로 분석하였으며, 그 결과 기판온도와 박막 두께에 따른 YBCO 박막의 a 축, c 축 성장의 의존성을 확인하였다. -
In this work, PZT(20/80)/(80/20) heterolayered thin film that has the tetragonal and rhombohedral structure was fabricated by Sol-Gel method spin-coated on the Pt/Ti/
$SiO_2$ /Si substrate by turns. The thickness of PZT-1 film obtained by six-times of drying/sintering process was about 480[nm]. This procedure was repeated several times to form PZT heterolayered thim film. PZT-5 thin films with top layer of tetragonal PZT(20/80) thin film showed dense grain structure and PZT-6 thin film with top layer of rhombohedral PZT(80/20) thin film showed the microstructure without rosette. Dielectric constant increased with increasing the number of coatings, and it was about 13S5 at PZT-6 thin film. Dielectric loss was not depend on the number of coatings. -
서로 다른 두께를 가진 다층구조
$BaTiO_3$ 박막의 절연신뢰성을 time-zero dielectric breakdown (TZDB) 기법과 time-dependent dielectric breakdown (TDDB) 기법을 사용하여 평가하였으며 통계적 방법을 이용하여 그 결과를 분석하였다. 다층구조$BaTiO_3$ 박막은 rf-magnetron sputtering 방법으로 ITO가 코팅된 유리기판 위에 형성되었다 TZDB 측정 결과, 박막의 두께가 증가 할수록 최고 빈도수를 보이는 항복전기장의 세기는 낮아지는 것으로 확인되었으며, 두께에 따라 다른 항전기장의 분포를 보였다. TDDB 결과로부터 박막의 두께 증가에 파라 안정적인 시간거동 특성이 확인되었으며 이것은 항전기장의 분포 특성과 관계가 있는 것으로 보인다. -
유전체 PLT(28) (
$Pb_{0.72}La_{0.28}Ti_{0.93}O_3$ ) 박막을 레이저 어블레이션 기법으로 Pt/Ti/$SiO_3$ /Si기판을$500^{\circ}C{\sim}700^{\circ}C$ 까지 가열한 상태에서$O_2$ 분위기에서 증착시켰다. 증착된 박막은 SEM, XRD 등의 구조적 분석을 통하여$600^{\circ}C$ 이상에서 증착된 경우, (111)방향으로 우세하게 성장한, 결정성이 양호한 박막임을 확인하였다. 박막의 전기적 특성은, 증착 온도가$650^{\circ}C$ 일 때 약 1400정도의 높은 비유전율을 얻었으며, 전하저장밀도는 100[KV/cm]에서 약 9[${\mu}C/cm^2$ ]이었다. -
A phase analysis in the solid solution of (1-x) PbFe1/2Nb1/2O3-xPbCo1/2W1/2O3 is conducted by dielectric properties, heat capacity and E-P hysteresis at x=0.1 interval. Lattice constants and superlattice intensity are analyzed by the x-ray diffraction, and the temperature - composition phase diagram is determined. The system is found to form a solid solution of perovskite structure throughout the entire composition range, but the nature of phase transitions changes from ferroelectric-paraelectric for
$0{\leq}x{\leq}0.5$ to antiferroelectric-paraelectric for$0.6{\leq}x{\leq}1.0$ . The transitions of ferroelectric-paraelectric and antiferroelectric-paraelectric for$0.2{\leq}x{\leq}0.5$ and for$0.6{\leq}x{\leq}0.8$ , respectively, are diffuse, while those of the ferroelectric-paraelectric and the antiferroelectric-paraelectric for$0.0{\leq}x{\leq}0.1$ and$0.9{\leq}x{\leq}1.0$ , respectively are sharp. -
In conducting systems based on Langmuir - Blodgett (LB) films, tetracyanoquinodimethane(TCNQ) derivatives have been extensively studied as electron acceptor molecules. We have fabricated N-docosyl N'-methyl viologen diTCNQ (DMVT) anion radical LB film and investigated the FT-IR, ESR, and AFM images as the optical, magnetic properties and morphology of the LB film. We have measured in-plane electrical conductivity with number of layers. The in-plane conductivities are approximately
$10^{-7}{\sim}10^{-6}\;S/cm$ . -
Langmuir-Blodgett(LB) method is one of the ways of fabricating organic ultra thin films. It is well known that It has the advantage to control the alignment and orientation of the molecules in the films. Metallo-phthalocyanines (MPcs) are sensitive to electron affinitive toxic gaseous molecules, such as
$NO_2$ , NO,$SO_2$ . In this study, thin films of octa-dodecyloxy copper-phthalocyanine were prepared by LB method and characterized by using UV/Vis absorption spectroscopy and ellipsometry. Optimal transfer condition of LB films was investigated and preliminary results of current-voltage (I-V) characteristics of these films exposed to$NO_2$ gas as a function of film thickness. -
Among the fuel cell system, solid oxide fuel cell is constructed of ceramics, so stack construction is simple, power density is very high, and there is no corrosion problem. The purpose of this research is to investigate the characteristics of state of art for SOFC.
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Direct methanol fuel cell based on a proton-exchange membrane electrolyte was investigated. 60% Pt-Ru/C and 60%Pt/C catalysts were employed for methanol oxidation and oxygen reduction, respectively. Morphologies of the catalysts were investigated by x-ray power diffraction, energy dispersive x-ray spectroscopy, and transmission microscopy. Electrochemical characteristics of the catalysts were tested by using cyclic voltametry technique. I-V characteristics of the fuel cell were tested by changing methanol concentration, temperature, and Nafion type as a proton-exchange membrane electrolyte. AC impedance technique was used to investigate the electrochemical performance of the fuel cell. The performance of single cell was enhance with increasing cell temperature. High operation temperature attributed to the combined effects of the reduction of ohmic resistance and polarization. High cell voltage was obtained from the concentration of 205M methanol. With Nafion 112, a current density of
$230mA/cm^2$ at 0.55V was obtained from the concentration of 2.5M methanol. -
In order to obtain key technologies for a kW class internal humidifying proton-exchange-membrane fuel cell (PEMFC) a single cell with a large electrode area has been designed and manufactured and the performance of large area membrane/electrode assemblies (MEAs) has been evaluated by using the single cell. A small area MEA made of commercial E-TEK electrode and Nafion 117 membrane showed a performance of 0.7V,
$300mA/cm^2$ whereas large area MEA made of catalyst layer on carbon support and Nafion 117 showed a lower performance. To improve the performance of large MEA direct coating of catalyst was carried out on the membrane using a screen printer. -
The metallic interconnector has a superior property than the ceramic interconnector in the point of the cell performance, but has problems to form oxide films on the interconnector surface during cell operation and induce cracking in the cell due to the stress by the thermal expansion coefficient difference with stabilized Zr electrolyte. For solving the problems in the metallic interconnector, new and modified materials have been investigated. In this paper,
$LaCrO_3$ dispersed Cr was evaluated in high temperature oxidized characteristics, sintering density, electrical conductivity and various thermochemical properties. The test results show that$LaCrO_3$ dispersed Cr has more superior properties than that of conventional alloy interconnector and$LaCrO_3$ dispersed Cr can be used as an interconnector in SOFC. -
Two kinds of optically-triggered p-i-n switches with planar and V-groove structures have been fabricated with gold-doped silicon. The V-groove device exhibits a higher threshold voltage and is more sensitive to light. The minimum optical power indicates that a certain minimum illumination is required to optically turn on the silicon p-i-n devices.
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This paper reports the characteristic of tile MIS structure composed of the LPCVD nitride on the oxide for the hydrogen gas detection. Pt was used as catalytic metal for detecting the hydrogen gas and the flat band voltage shift was measured at various hydrogen concentration. We found the flat band voltage shift was proportional to the hydrogen concentration.
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본 논문에서는 SDB(Silicon Direct Bonding) 기술을 적용하여 빠른 스위칭 속도 및 낮은 도통 전압을 갖는 1200v 10A n-ch IGBT를 제작하였다. 기존의 epi wafer를 이용한 IGBT 제작시 스위칭 속도 개선을 위한 전자조사 방법을 사용하지 않고 buffer의 농도를 증가시켜 아노드 영역의 정공 주입 효율을 제어하여 90ns의 스위칭 속도를 가지며, 2.0V의 도통전압을 갖는 IGBT를 구현하였으며, SDB IGBT 제작시 bonding 계면의 문제 및 표면의 particle 및 결함이 소자의 전기적 특성에 미치는 영향을 고찰하였으며, 이를 실험 결과와 비교 평가하였다.
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We have investigated the latchup characteristics of BL/BILLI retrograde twin well CMOS that has the high energy ion implanted buried layer to intend for more improvement of latchup compare to conventional retrograde well and BILLI structures. We explored the dependence of various latchup characteristics such as n+ trigger latchup and p+ trigger latchup on the buried layer implant doses. We show various DC latchup characteristics that allow us to evaluate each technology and suggest guidelines for the reduction of latchup susceptibility.
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We have investigated the crystallization properties of
$Te_x(Sb_{85}Ge_{15})_{100-x}$ (x=0.3, 0.5, 1.0 at.%) thin films as observing the reflectance change, XRD and SEM. The reflectance difference(${\Delta}R$ ) between amorphous and crystalline phases appears appoximately 20%, in all films, at 780nm(diode laser wavelength). In the case of$Te_{0.5}(Sb_{85}Ge_{15})_{99.5}$ thin film, especially,${\Delta}R$ is about 30%. Also, amophous-to-crystalline phase change is observed at all films. Therefore,$Te_{0.5}(Sb_{85}Ge_{15})_{99.5}$ thin film can be evaluated as attractive optical recording material with low loss and high contrast ratio. -
In this study, the mechanism underlying the corrosion problem have been investigated using X-ray photoelectron spectroscopy(XPS) and scanning electron microscopy(SEM), AES(Auger electron spectroscopy) In regard to the removal of Al-Cu corrsion, the subsequent treatment of the
$SF_6$ plasma has also been completed. This work evaluated the effects of grain boundary on the AlCu after dry etching and the role of subsequent$SF_6$ plasma for the removal of AlCu corrosion. -
The oxynitride films were photo-chemically deposited by ArF(wave length: 193nm) excimer laser CVD used to excite and dissociate gas phases
$Si_2H_6$ ,$N_2O$ , and$NH_3$ molecules. We obtained various electrical properties when we varied wafer cleaning procedures consisted of a conventional RCA and a two-dip step[4]. The results show the films have low leakage currents and good TZDB properties. We also analyzed the composition of the oxynitride films which have homogeneous composition throughout the film. -
In this paper, structural, optical and electrical properties of
$Cd_{1-x}Zn_xS$ thin films prepared by co-evaporation method were studied. The crystal structure of$Cd_{1-x}Zn_xS$ films deposited at a substrate temperature of$150^{\circ}C$ was hexagonal with the c axis aligned perpendicular to the substrate. As increasing composition parameter x, the intensity of (002) peak decreased, which means poor crystalline and decreasing of preferential orientation. The optical bandgap of$Cd_{1-x}Zn_xS$ films varies from 2.41eV for CdS to 3.48eV for ZnS with x. The resistivity of the$Cd_{1-x}Zn_xS$ films increased with x. -
In this study, partially-depleted SOI MOSFET with multi-gate was fabricated on p-type SIMOX(Seperation by Implanted Oxygen). As increase the number of its gate, increase the breakdown voltage. But kink effect was not affected by the number of its gate. However, it is known that the asymmetric gate structure reduce kink effect. So if asymmetric multi-gate applied to partially-depleted SOI MOSFET, it is expected that the breakdown voltage of SOI MOSET with asymmetric multi-gate is higher than that of SOI MOSFET with single gate and that kink effect is reduced by SOI MOSFET with asymmetric multi-gate.
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전류 센싱 MOSFET의 센싱 셀과 메인 셀의 온저항 모델을 달리 세워 원자재 산포에 따른 소자의 특성 산포 분량의 원인을 규명하였다. 에피의 농도와 두께가 증가할수록 센싱 셀의 온저항이 메인셀보다 작아지며 농도와 두께의 변화가 있을때의 온저항 변화율도 작은것으로 나타났다. 원자재 산포에 의한 SENSE FET 특성 산포를 줄이기 위해서는 정사각형 형태의 SENSE cell 배치가 효과적이며 센스 셀과 메인 셀의 간섭을 방지하기 위해서는 센싱 저항을 센스 셀의 온저항의 1/10 이하로 설계하고 간격이 최소한 에피 두께 이상이 되어야함을 밝혔다.
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본 연구에서는 latch-up 개선책의 일환으로 개발중인 매립층을 갖는 retrograde well의 형성기술과 더불어 공정 단순화를 목적으로 개발된 BILLI (Buried Implanted Layer for Lateral Isolation) well 구조[1]에 대한 공정 유기 결함을 분석하고 그에 의한 소자 열화 특성을 분석 하였으며 그 개선책을 제시 하고자 하였다. 매립층 형성에 의한 유기결함은 접합 누설전류와 Gate oxide 신뢰성을 열화 시켰으나 이온주입 후
$1000^{\circ}C$ 이상의 온도에서 10sec 정도의 RTP anneal에 의해 그 소자 특성이 개선되며 표면 결함이 감소함을 알 수 있었다. -
금속기판상 초전도
$YBa_2CU_3O_{7-{\delta}}$ (YBCO) 박막을 yttria-stabilized zirconia (YSZ) 완충막을 이용하여 in situ 펄스 레이저 증착법에 의해 증착하였다. YBCO 박막을 직접 금속기판에 증착하게 되면 YBCO 박막과 금속기판 사이의 계면에서 상호확산현상이 발생하기 때문에 이를 방지하기 위해 YSZ 완충막이 사용되었다. YSZ 완충막의 증착온도가 박막의 결정성과 전기적 특성에 미치는 영향을 알아보기 위해 YSZ 완충막은 여러 가지 온도로 증착되었다. YBCO 박막의 증착온도와 같은 온도로 YSZ 완충막을 증착했을 때보다 YBCO 박막의 증착온도보다 높은 온도로 YSZ 완충막을 증착했을 경우, 증착된 YBCO 박막은 x선 회절에 의해 c 축 방향으로 성장하였음을 알 수 있었고, 저항이 0이 되는 임계온도가 83K가 되는 실험 결과를 얻었다. -
This study was performed to investigate the deposition mechanism of
$SiO_2$ by ArF excimer Laser(193nm) CVD with$Si_2H_6$ and$N_2O$ gas mixture and evaluate Laser CVD quantitatively by modeling. In this study, new model of$SiO_2$ deposition process by Laser CVD is introduced and deposition rates are simulated by computer with the basis on this modeling. And simulation results are compared with experimental results measured at various conditions such as reaction gas ratio, chamber pressure, substrate temperature and laser beam intensity. -
A hydrogen gas sensor utilizing Pt/
$SnO_2$ system was fabricated by the pressed pellet method. The crystal structure, direction of the crystal, crystal size and microstructure between the catalyst and the support ($SnO_2$ ) were characterized with Electron Diffraction Analysis, Transmission Electron Microscopy, Scanning Electron Microscopy. After the reactor with a Pt/$SnO_2$ sample was run with a flow rate of 30sccm (a mixture of$0.5%H_2$ in$N_2$ ) for a while, the resistance of$SnO_2$ was saturated, but the$SnO_2$ kept absorbing$H_2$ gas.$H_2$ gas sensing properties of Pt/$SnO_2$ were investigated at several temperatures. As a result, it was observed that Pt/$SnO_2$ has high sensitivity at$300^{\circ}C$ and$400^{\circ}C$ . -
Several methods for electrode fabrication of phosphoric acid fuel cell(PAFC) have been studied. The conventional methods that include a coating method and a rolling method, have disadvantages of a very complicated drying process and a hot pressing process for making a large electrode. In this study, to solve these problems, the mixing method of coating and rolling processes has been developed. In the mixing method, the electrode was coated on the electrode support and, after drying the coated layer, was rolled at room temperature and then sintered at
$350^{\circ}C$ . The single cell performances of the electrodes fabricated by several methods were examined and the mixing method appeared a good cell performance of 0.65 V,$260\;mA/cm^2$ . Also the single cell with an area of$2000\;cm^2$ was manufactured and its performance attained 0.593 V, 300 A. -
We describe the working principle, the design, and the characteristics of two-chip integrated humidity sensor. The sensing element was manufactured using polyimide. The interface circuits were developed based on a charge redistribution between capacitors. The sensor and signal conditioning chips were packaged together in the same package. The sensor showed excellent linearity over a wide range of relative humidity.
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In this study, We fabricated thin film magnetic core inductors by using thin film manufacturing techniques such as photolithography and wet etching process. The inductors were prepared using multi-layered CoNbZr/Cu/CoNbZr. These devices are measured at high frequency range of
$1\;MHz{\sim}1\;GHz$ . -
This paper is to study and develope a measurement apparatus for ferroelectricity. The apparatus consists of wave generation part, high voltage amplifier part, measurement part, data acquisition part and the related controll circuits. Single or double excitation wave is digitalized and sent to the external RAM of wave generation part by personal computer. These datas saved in the RAM are converted to analog excitation wave through D/A converter. The frequency of excitation wave is depend on the read-out speed of the RAM by clock pulse. Such generated wave is applied to high voltage amplifier as a input voltage. The output of high voltage amplifier is applied to ferroelectrics and the response is obtained from the charge amplifier of measurement part. The response is sampled and converted to digital datas through AID converter. These digital datas are automatically saved in the external RAM of acquisition part. The computer takes the digital datas and calculates the electric displacement D, the electric field and the dielectric constant
$\varepsilon$ . We tested for PZT ceramic sample and could observed the D-E hysteresis lops and${\varepsilon}_s$ -E hysteresis loops with good forms. -
The distribution of coercivity in the thickness direction were investigated by using Kerr hysteresis loop tracer for the Co-Cr films deposited by Facing Targets Sputtering apparatus. It
$H_{c{\bot}}(S)- H_{c{\bot}}(I)$ correlated strongly with${\Delta}H_c$ , which represents the degree of distribution of coercivity. Furthermore, the Cr content was varied in order to improve the coercivity of intial growth layer$H_{c{\bot}}(I)$ took a maximum value of 750 Oe and the distribution of coercivity became sharper at the Cr content of 25 at.%. -
The necessity of this work is described with present problems in the application of computer simulation methods to electrical material research. Author proposes and develops method which can calculate properties such as dielectric and piezoelectric constants for ZnO. The method based on ab-initio method. It is found that these properties can be calculated with a good precision by this method.
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In this paper, PNN-PZN-PZT ceramics were fabricated with various mole ratio of the PZT[
$Pb(Zr_{1/2}Tid_{1/2})O_3$ ]. PNN [$Pb(Ni_{1/3}Nb_{2/3})O_3$ ] and PZN[$Pb(Ni_{1/3}Nb_{2/3})O_3$ powders prepared by double calcination and PZT powders prepared by molten-salt synthesis method. The formation rate of perovskite phase in PNN-PZN-PZT ceramics could be obtained about 92% at PZT 0.3 mole ratio. The relative permittivity of specimen with PZT 0.3 mole ratio was shown 5,320 and appeared the relaxor ferroelectric feature. The maximum piezoelectric coefficient$d_{31}$ to be used for evaluation the displacement of piezoceramics in PNN-PZN-PZT ceramics was$324{\times}10^{-12}$ (C/V) at the vicinity of morphotropic phase boundary and was larger than that of solid PZT ceramics($120{\times}10^{-12}C/V$ ). -
In this paper, PNN-PZN-PZT ceramics were fabricated with various mole ratio of the PZT[
$Pb(Zr_{1/2}Tid_{1/2})O_3$ ]. PNN [$Pb(Ni_{1/3}Nb_{2/3})O_3$ ] and PZN[$Pb(Ni_{1/3}Nb_{2/3})O_3$ powders prepared by double calcination and PZT powders prepared by molten-salt synthesis method. The formation rate of perovskite phase in PNN-PZN-PZT ceramics could be obtained about 92% at PZT 0.3 mole ratio. The relative permittivity of specimen with PZT 0.3 mole ratio was shown 5,320 and appeared the relaxor ferroelectric feature. The maximum piezoelectric coefficient$d_{31}$ to be used for evaluation the displacement of piezoceramics in PNN-PZN-PZT ceramics was$324{\times}10^{-12}$ (C/V) at the vicinity of morphotropic phase boundary and was larger than that of solid PZT ceramics($120{\times}10^{-12}C/V$ ). -
We have made disperse diazo black D(DBD) thin films using Langmuir-Blodgett(LB) and vacuum-evaporation technique. Physical and optical properties of the films were investigated. Solution was made with a concentration of
$10^{-3}mol/{\ell}$ using chloroform. Moving wall apparatus, (NL-LB140S-MWC) was employed to make the LB films. X,Y and Z-type LB films were manufactured and studied UV/visible absorbance spectra and morphology of surface using atomic force microscopy(AFM). Vacuum-evaporated DB D thin films were made at a pressure of$10^{-5}$ torr. The absorption peaks were observed at 200 and 400 nm in the LB films and vacuum-deposited films. We have also studied photoluminescence spectrum of the DBD films. -
Relations between the composites of SiC-
$ZrB_2$ electro-conductive ceramic composites and their electrical resistivity, as well as their temperature, were investigated. The electrical resistivity of hot-pressed composites was measured by the Pauw method in the temperature of RT to$100^{\circ}C$ . The electrical resistivity of the composites follow the electrical conduction model for a homogenous mixture of two kinds of particles with different conductivity. Also the electrical resistivity versus temperature curves indicate the formation of local chains of$ZrB_2$ particles. In the case of SiC-$ZrB_2$ composites containing above 30Vol.%$ZrB_2$ showed PTCR, whereas the electrical resistivity of SiC-15Vol.%$ZrB_2$ showed NTCR. -
The various type Ag sheathed Bi-2223 tapes have been were fabricated by Powder-in-tube(PIT) process. The critical current density could be improved with the value of
$23,000\;A/cm^2$ (77 K, zero field) in the single concentric Bi-2223 tape. The bending property dependence of$I_c$ was improved in the double concentric Bi-2223 tape compared with single filamentary and single concentric one. -
Zinc oxide varistors which contain rare earth metal oxides have been developed. These Varistors are widely used for low voltage surge-protection devices and high voltage arresters for electric power stations. The characteristics of varistors with praseodymium oxide as a principal additive are discussed. A two-phase microstructure with an intergranular phase between the ZnO grains.
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Lim, Sung-Hun;Yim, Seong-Woo;Park, Kyung-Kuk;Park, Jong-Kwang;Cho, Dong-Eon;Han, Byung-Sung 1345
$YBa_2Cu_3O_x$ samples were fabricated by MPMG(Melt Powder Melt Growth). The effects of the$Y_2BaCuO_5$ and Ag addition on$YBa_2Cu_3O_x$ were studied throuth the Jc, Tc and magnetization. For the application of the bulk HTSC to current limiter, fly wheel and current lead and so on, the critical charateristics were investigated and compared with the solid sintering method. -
TFT2DS was utilized to provide the usefulness as an analytic and design tool. In this paper, the general effects of channel length of an inverted staggered amorphous silicon thin film transistor on its characteristics were investigated. The results obtained from these experiments would be adopted to the optimized device designs and advanced simulations of their electrical properties.
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Transparent conductive thin films have found many application in many active and passive electronic and opto-electronic devices as like flat Panel display electrode and window heat mirror, etc. Low resistivity and high transmittance of this films can be obtained by controlling deposition parameters, which are oxygen partial Pressure, substrate temperature and dopant concentration. In this study, We prepared non-stoichiometric and Sb-doped thin films of tin dioxide by reactive DC magnetron sputtering technology. The lowest resistivity of about
$3.0{\times}10^{-3}\;{\Omega}cm$ and 80% transmittance in the visible light region have heed obtained at optimal deposition condition. -
In this study, the ferrite/rubber composite microwave absorbers mixed Ni-Zn ferrite and
$Ni_2Y$ ferroxplana were prepared in order to control matching condion. The variation of the material constants($\dot{\varepsilon}$ ,$\dot{\mu}$ ) and microwave absorbing characteristics were investigated with various ferrite mixing ratio. The material constants of ferrite/rubber composite microwave absorber could be controlled by variation ferrite mixing radio. The matching frequency and thickness could be controlled with various ferrite mixing ratio. -
In this paper, the performance of Pt/
$WO_3$ and Pt-$WO_3$ electrodes was studied for the direct methanol fuel cell. The characteristics of Pt/$WO_3$ electrode which was prepared by using electrodeposition method was tested with half-cell experiment. The characteristics of Pt-$WO_3$ /C electrode which was Prepared by using freeze-drying method was tested with a single cell experiment. The performance of DMFC single cell which was prepared by Pt-$WO_3/C$ and Pt/C showed a current density of$32mA/cm^2$ at$110^{\circ}C$ & 0.3V(0.5mg Pt/$cm^2$ ). -
Zinc oxide-based MOV was fabricated with
$SiO_2$ additive ranging from 0.5 to 4.0 mol%, and the microstructure and electrical characteristics were investigated.$Zn_2SiO_4$ phase formed by$SiO_2$ additive was distributed at ZnO grains, grain boundaries, and multiple grain junctions. As the content of$SiO_2$ additive increases, average grain size decreased from 40.6 to$26.9{\mu}m$ due to the Pinning effect by$Zn_2SiO_4$ at grain boundaries Breakdown voltage and nonlinear exponent increased, and leakage current decreased in the range of$11.2{\sim}6.14{\mu}A$ with an increasing$SiO_2$ . Donor concentration and interface state density decreased, and barrier height increased in the range of$0.71{\sim}1.04eV$ with an increasing$SiO_2$ . While, as the content of$SiO_2$ additive, apparent dielectric constant decreased, peak frequency of dissipation factor decreased in the range of$6.45{\times}10^5{\sim}3.00{\times}10^5Hz$ , and dissipation peak was$0.31{\sim}0.22$ at Peak frequency. -
Planar type magnetized inductively coupled plasma etcher has been built. The density and temperature of Ar plasma are measured as a function of rf power, external magnetic field, and pressure. The oxide etch rate and selectivity to polysilicon are measured as the above mentioned conditions and self-bias voltage.
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본 논문에서는 PET/PET 필름과 인터페이스를 갖는 PET/SEMI/PET필름에서의 전기 전도도와 공간전하분포를 고찰하였다. 반도전층을 가지고 있는 PET/SEMI/PET 필름의 전도전류는 PET/PET에 비하여 높았으며 특히 전압 인가후 순간적인 전류가 급격하게 소멸하였다. 또한 PET/SEMI/PET 필름의 공간전하 분포는 PET/PET 필름에 비해 높은 전하 형성을 보였다.
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In this study, 3-D underwater object recognition using ultrasonic sensor fabricated with porous piezoelectric ceramics and SCL(Simple Competitive Learning) neural networks are presented. The recognition rates for the training data and the testing dara were 96 and 93%, respectively.
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In this study, 3-D underwater object restoration using ultrasonic sensor fabricated with porous PZT-Polymer 3-3 type composite are presented Using the acquired underwater object data
$16{\times}16$ pixels, Modified SCL neural networks using the$16{\times}16$ low resolution image was used for underwater object restoration of$32{\times}32$ high resolution image. -
Mechanical and electrical properties of mica/epoxy composite materials were investigated by dynamic mechanical analyzer(DMA) and dielectric analysis (DMA). Both modulus and permittivity of sound specimens were higher than those of aged specimens. Two results show that
$tan{\delta}$ of sound specimens is lower than that of aged specimens. DMA results showed that glass transition temperatures of sound and aged specimens are observed to be$87.16^{\circ}C$ and$88.38^{\circ}C$ , which increases with the increase of aging time. -
Diamond-like carbon(DLC) thin films are produced by using a filtered cathodic vacuum arc(FCVA) deposition system. Different magnetic components, namely steering, focusing, and filtering plasma-optic systems, are used to achieve a stable arc plasma and to prevent the macroparticles from incorporating into the deposited films. Effects of magnetic fields on plasma behavior and film deposition are examined. The carbon ion energy is found to be varied by applying a negative (accelerating) substrate bias voltage. The deposition rate of DLC films is dependent upon magnetic field as well as substrate bias voltage and at a nominal deposition condition is about
$2{\AA}/s$ . The structural properties of DLC films, such as internal stress, relative fraction of tetrahedral($sp^3$ ) bonds, and surface roughness have also been characterized as a function of substrate bias voltages and partial gas($N_2$ ) pressures. -
Dimond-like carbon(DLC) films have been deposited by using both rf plasma-enhanced chemical vapor deposition (PECVD) and filtered cathodic vacuum arc (FCVA) deposition systems. Effects of deposition conditions, such as dc self-bias,
$CH_4$ gas pressure, substrate bias, and$N_2$ partial pressure, on the structural and electrical properties of DLC films are examined. The experimental results obtained have also been discussed by considering a theoretical model for film growth. -
The MCFC 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. -
The object of this research is to develop various composing material for Solid Oxide Fuel Cell generation system, and to test single cell performance manufactured. So we try to present a guidance for developing mass power generation system. We concentrated on development of manufacturing process for cathode, anode and electrolyte.
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Kwon, Oh-Kwan;Oh, Se-Woon;Kim, Young-Kwan;Choi, Jong-Sun;Shin, Dong-Myung;Sohn, Byung-Chung 1391
The thin films of$\alpha$ -Sexithiophene($\alpha$ -6T) were deposited by Organic Molecular Beam Deposition(OMBD) technique. The$\alpha$ -6T was synthesized and Purified by the sublimation method The thin films of the$\alpha$ -6T were deposited under various deposition conditions. The effects of deposition rate substrate temperature, and vacuum pressure on the formation of these films have been studied. The molecular orientations of$\alpha$ -6T films were investigated with the polarized electronic absorption spectroscopy. The molecules in the$\alpha$ -6T film deposited at a low deposition rate under a high vacuum were almost aligned Perpendicular to the substrate. The film deposited at an elevated substrate temperature(${\sim}90^{\circ}C$ ) showed higher conductivity than deposited at room temperature. -
In order to investigate the interfacial effects on the aging of power cables, we analyzed recently failed cables using characterization techniques. In this study, some cables showed a convolution which can cause the concentration of electric field and carbonized impurities at the surface of insulation. Also there is a relation between the degree of cross- linking and volume resistivity. From the hot oil test, the sites of water tree and void coincided with each other.
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This paper presents experimental results on the recycling aluminum wires used in the actual field. Several testings were carried out with the recycled aluminum wires to prove that they are reusable. Mechanical, electrical and oxidation properties of recycled and new ACSR
$160\;mm^2$ were campared after 7.5 year service aging at the salt comtaminated areas of Korean peninsular. -
The stability of superconducting wires was studied by considering temperature and magnetic field. We measured critical current density of
$Nb_3Sn$ tape at 4.2 K, 12 K, 13 K and 14 K in various field. The critical current density at 4.2 K, 6 T is 16.5 times higher than at 12 K, 6 T. We expressed the critical current density as a function of temperature and magnetic field, expanding on work by Hampshire, et al. -
To evaluate the effects of impurities on insulating properties of polymeric insulator in high electric power distribution cable, OIT and OMT were measured. By using Eyring plot, the thermodynamic parameters of
${\Delta}H$ and${\Delta}S$ could be obtained. -
A microstructure of realistic ZnO varistor is constructed by Voronoi network and studied via computer simulation. In this network, the grain boundary condition is fitted from the experimental data. The effect of the variation of the uniformity of the varistor on the electrical characteristic of the varistor is simulated by using this boundary condition.
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Arrhenius plots are useful in predicting long-term use temperatures of organic materials and in choosing parameters for accelerated aging. The effects of antioxidant on the heat resistance and temperature index of EPDM rubber used for electrical insulation were investigated. The short-time points were obtained by 50% retention of elongation at break.
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The thin film that is electrically conductive and optically transparent is called conductive transparent thin film. ITO(Indium-Tin Oxide) which is a kind of conductive transparent thin film has been widely used in solar cell, transparent electrical heater, selective optical filter, FDP(Flat Display Panel) such as LCD (Liquid Crystal Display), PDP(Plasma Display Panel) and so on. Especially in PDP, ITO films is used as a transparent electrode in order to maintain discharge and decrease consumption power through the improvement of cell structure. In this study, we prepared ITO by reactive r.f. sputtering with indium-tin(Sn wt 10%) alloy target instead of indium-tin oxide target. The ITO films deposited at low temperature
$150^{\circ}C$ and 8%$O_2$ partial pressure showed about$3.6{\Omega}/{\square}$ . At the end of firing, the resistance of ITO was decreased, the optical transparence was improved above 90%. -
The electrical breakdown characteristics of the synthetic fluids No.2 of KS class VII used for insulating and cooling the materials for the ignition coil are studied. Also, Benzotriazole(BTA) as the streaming electrification suppressant additive is added to the oil, and the change of electrical properties due to different BTA concentration is investigated. To investigate the electrical characteristics, the breakdown strength of each specimen by an experiment for AC breakdown are analyzed. The breakdown strength of specimen by adding BTA is higher than virgin specimen in low e region, but lower than that in high region because of melting BTA. It is considered that the effective content of BTA as charge suppressant additive is about 10[ppm] from the results of AC breakdown.
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In this paper, the dielectric properties is made researches by the dose of electron beam in order to investigate the electrical properties for transformer oils due to electron beam irradiation. To measure the dielectric loss of irradiated specimen, the liquid electrode of coaxial cylindrical shape is used, and its geometric capacitance is 16 [pF]. And the dielectric dissipation factor,
$tan{\delta}$ , is measured by using the Video Bridge 2150. The thermal static oven with an automatic temperature controller is used so as to apply specific temperature to specimen. This experiments for measuring the dielectric loss is performed at$20{\sim}120[^{\circ}C]$ in temperature range,$30{\sim}1.5{\times}10^5[Hz]$ in frequency and$300{\sim}500[mV]$ in voltage. -
To make clearly breakdown rl1cchanism and path at interface of crystal and amorphous region, we fabricated HDPE and LDPE thin film by dropping solution onto glass substrate. then annealed the film at
$140^{\circ}C$ . Shperulites formation and its interface prepared from of two different materials differ from each other. Comparing breakdown site and breakdown field of HDPE with those of LDPE, we can demonstrate the reason that breakdown holes in HDPE are concentrated on the region of interface. From the result, It is appeared that interface of crystallites lead not to weakness as electrical insulating materials. -
저전압 구동이 가능한 교류구동형 박막전기발광소자를 구현하기 위해 높은 유전상수를 가지며 특히 광학적 굴절률이 발광박막과 유사하여 광학적 특성 개선에도 효과적인 것으로 알려져 있는
$Ta_2O_5$ 를 제조하였다.$Ta_2O_5$ 박막은 rf-magnetron sputtering방법으로 형성하였으며 기판온도, working pressure, 박막의 두께에 따른 전기적인 특성을 조사하였다. 10mTorr에서 제조된$Ta_2O_5$ 박막은$22{\sim}26$ 의 비유전율을 보였고, 유전손실은$0.007{\sim}0.03(1kHz{\sim}10kHz)$ 의 값을 보였다.$100^{\circ}C$ 에서 제조된 박막의 전하저장용량은$7.9{\mu}C/cm^2$ 이었다. 제조된 박막의 항복전압은 인가 전압의 극성에 의존하며, 전류특성은 기판온도와 200nm와 300nm의 두께에서는$V^{1.95}{\sim}V^{2.35}$ 에 비례하는 space charge limited current특성을 보였고, 400nm에서는 Poole Frenkel특성을 보였다. 이상의 결과로 TFEL소자에 응용에 적합한$Ta_2O_3$ 박막은$200^{\circ}C$ 에서 증착되고 200nm와 300nm인 것으로 나타났으며, 제조된 MIS구조(ITO-$Ta_2O_5$ -ZnS-Al)의 ACTFEL소자에서의 전도전하는 각각$13uC/cm^2$ ,$8.3uC/cm^2$ 로 조사되었다. -
In this study, piezoelectric transducer were designed and manufactured using PZT-5A which have relatively high electromechanical coefficient. A epoxy is a good material as matching and backing layers. The envelope was reduced 60% as using matching layer and 76% as using matching and backing layer. NDT was successfully carried out for aluminum test pieces. Distance error and resolution of PZT-5A probe were improved as increasing frequency. Envelope was effectively reduced by backing layer but sensitiveness was poor.
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A solar cell conversion effiency was degraded by grain boundary effect in polycrystalline silicon. To reduce these effects of the grain boundaries, we investigated various influencing factors such as preferential chemical etching of grain boundaries, grid design, transparent conductive thin film, and top metallization along grain boundaries. Pretreatment in
$N_2$ atmosphere and gettering by$POCl_3$ and Al were performed to obtain polycrystalline silicon of the reduced defect density. Structural, electrical, and optical properties of solar cells were characterized. Improved conversion efficiencies of solar cell were obtained by a combination of Al diffusion into grain boundaries on rear side, fine grid finger, top Yb metal grid on Cr thin film of$200{\AA}$ and buried contact metallization along grain boundaries. -
ZnO shows the properties of wide conductivity variation, high optical transmittance, and excellent piezoelectricity. Using these properties of ZnO, the material applications were extended to sensors, SAW filters, solar cells, and display devices. This paper investigated transmittance influencing factors for thin film ZnO grown by RF magnetron sputtering. The growth rate and structural investigation were carried out in conjunction with optical transmittance characteristics of thin film ZnO. The glass substrate temperature of
$175^{\circ}C$ exhibited a preferential crystallization along (002) orientation. Transmittance of ZnO film deposited at the substrate temperature of$175^{\circ}C$ showed higher than 92%. An active sputter gas was investigated with a variation of$O_2$ partial pressure from 0 to 10% in an Ar atmosphere. ZnO film grown in 100% Ar gas shows that a reduced transmittance of 82% at the short wavelengths and decreased resistivity value. As the partial pressure of$O_2$ gas increased, the optical transmittance was increased above 90% at the short wavelengths, however, resistivity was drastically increased to higher than$10^4{\Omega}$ -cm. -
In this paper, CdS thin films, which were widely used window layer of the CdS/CdTe and the CdS/
$CuInSe_2$ heterojunction solar cell, were grown by chemical bath deposition, and The properties were investigated in detail. Cadmium acetate and thiourea were used as cadmium and sulfur source, respectively. And Ammonium acetate was used as the buffer solution. Also Ammonia was used for controlling pH concentration. The reaction velocity was increased with increasing reaction temperature and decreasing pH concentration. The crystal structure of CdS films grown with various pH concentration had the hexagonal structure with (002) plane peak. In the range of pH$9{\sim}9.5$ , the intensity of the peak was highest, and as increasing pH concentration, decreased the intensity of the peak except pH12. -
We investigated the electrical and CO sensing properties of ZnO-
$TiO_2$ composite ceramics. The electrical conductivities and relative dielectric constants of$TiO_2$ added ZnO increased with increasing$TiO_2$ content in air. The calculated dielectric constants of 3mol%, 5mol%, and 7mol%$TiO_2$ added ZnO were 7, 13, and 120, respectively. The measured CO sensivities were$1{\sim}6.42$ in the temperature range from$100^{\circ}C$ to$400^{\circ}C$ . -
This paper presents an analysing method to find out an optimum metal shape for insulation strength of SCI(Silicone Composite Insulator). Using finite element method, the interested parameters of the configuration such as a aspect of metal/silicone composite and a material properties are investigated and derived a thread of optimum design parameters.
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TEC(Thermoelectric conversion) is direct conversion method between thermal energy and electric energy. We studied on the mechanical, electrical and thermal properties of thermoelectric module and made experimental thermoelectric generator with BiTe material.
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Busbar made with Cu or Cu alloys and producted by Plastic manufacturing process. In this study, we research the manufacturing trend of Cu clad Al busbar for low cost and light weight which used for a electric power supply of distributing board. The objectives of this study is the manufacturing of composite busbar on electric power supply, the process and application for Cu clad Al busbar and the relation between electric properties and manufacturing operating process on contact parties.
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Properties of flashover in polymer insulators are very important under pollution environments. It is necessary to analyse flashover characteristics whether insulators are still safe or not. A lot of precious information can be got out of polluted polymer insulators through leakage current measurement. The behavior of partial arc discharge leads to flashover directly. It is possible to measure partial arc discharge as leakage current pulses analysis. The shape of histogram reflects degree of pollution, wetting and voltage stress level. It can be expressed by Weibull distribution function.
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In order to promote CO gas sensitivity,
$SnO_2$ added ZnO prepared. The electrical conductivities and dielectric constants decreased by increasing$SnO_2$ content in air. The electrical conductivities in 1000ppm CO atmosphere were larger than in dry air. The measured CO sensitivities were$1{\sim}15.2$ at$100^{\circ}C{\sim}480^{\circ}C$ . The maximum CO sensitivity of 15mol%$SnO_2$ added ZnO was 15.2 at$305^{\circ}C$ . -
The microwave dielectric ceramic properties of
$CaTiO_3-(Li_{1/2}Nd_{1/2})TiO_3$ were investigated. The solid solution of$CaTiO_3-(Li_{1/2}Nd_{1/2})TiO_3$ had the perovskite structure in the range of all composition. The dielectric constant and temperature coefficient of resonant frequency of solid solution were decreased with the contend of$(Li_{1/2}Nd_{1/2})TiO_3$ , whereas, the$Q{\times}f$ value was increased. In the$(1-X)CaTiO_3-X(Li_{1/2}Nd_{1/2})TiO_3$ system, the microwave properties could be controlled by the variation of X, X is weight fraction. Typical value of K=119,$Q{\times}f=2970$ and$TCF=14ppm/^{\circ}C$ were obtained for$0.2CaTiO_3-0.8(Li_{1/2}Nd_{1/2})TiO_3$ . -
The spinel
$LiMn_2O_4$ has been synthesized by solid-state reaction.$LiMn_2O_4$ which includes 3 mix$Li_2CO_3$ or$LiNO_3$ and$MnO_2$ prepared by Prelim heating at$350^{\circ}C$ for 24hr.$LiMn_2O_4$ fired at temp range from$600^{\circ}C$ to$800^{\circ}C$ for 48hr. The structure a electrochemical characteristics of spinel$LiMn_2O_2$ wh fabricated by changing sintering condition from st materials are investigated. The spinel$LiMn_2O_4$ prepared by the mixture of L CMD at$800^{\circ}C$ for 48hr showed an initial charge ca of 146mAh/g. The spinel$LiMn_2O_4$ prepared by the m of$LiNO_3$ /CMD at$600{\sim}800^{\circ}C$ for 48hr stabilized ch discharge capacity after 50th cycles. -
In this study we investigated the aging characteristic such as leakage current, dielectric loss, contact angle, of EPDM for outdoor use by thermal treatment. And also observed the color change of surface, changing of chemical ingredient of the marterials by optical microscope. SEMI, FTIR and EDX at the section and surface. The test result show that leakage current is increased with thermal aging time. contact angle and dielectric loss is slightly decreased. Moreover, micro-void or crack in bulk is severely increased with aging time. However, the result affect to the tan
$\delta$ at bulk of EPDM. It seems that carrier sources are removed by degassing with heat treatment. -
In this study, Organic electroluminescent(EU devices with multilayer structures were fabricated using tris (8-hydroxy quinolinate) aluminum(
$Alq_3$ ) as an electron-tran sporting emitting layer and TPD(N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine : aromatic diamine) as a hole-transporting layer. A cell with a structure of glass substrate/indium-tin-oxide(ITO)/$Alq_3$ /TPD/Mg:In exhibited bright green electroluminescence from the TPD layer. The peak intensity of TPD and$Alq_3$ different from spin coating and vacuum evaporation. The peak emission energy shifts to a higher energy with deposition technique. An emission peak at 500nm was achieved at a driving voltage of 30V. -
In this study, the
$Nb_3Sn$ wire was tried to fabricate by internal tin process to investigate the relationship between the processing parameters in a cold working and the microstructure. The critical current densities of$Nb_3Sn$ wires were evaluated in magnetic fields at 4.2 K.$Nb_3Sn$ compound layer was found to be formed between Nb core and Cu-Sn. The Cu part in the wire transformed to Cu-Sn by the reaction with Sn and the Sn in the Cu-Sn part reacted with Nb. -
We have fabricated a novel LDD structured polysilicon thin film transistor with a simple fabrication process, compared with the conventional LDD poly-Si TFT, without LDD implantation by employing taper etched
$SiO_2$ film instead of LDD implant mask. The leakage current of the novel LDD device is reduced significantly in OFF state while keeping the ON current to be almost identical to that of the non-LDD poly-Si TFTs. -
We investigated the breakdown characteristic of mineral oil according to applied voltage and tip radius. In this experiment, electrode system was point-plane geometry. The tip radius of needle was 5, 10, 20 and
$25{\mu}m$ , respectively. Applied voltage was AC and DC. We measured breakdown voltage for each tip radius with increasing electrode gap, 2mm to 10mm. Under nonuniform electric field, breakdown strength was higher when needle was negative than when needle was positive. Because it is polarity effects due to space charge. And the more sharp tip radius, whether we applied AC or DC, the higher breakdown strength. As tip radius increase, breakdown strength decreases exponentially. -
This paper describes a electrical tree simulation by fractal theory. Tree patterns produced by computer simulation with random numbers were studied from the point of view of fractal dimension. Tree patterns have a variety of shapes such as branch-like, bush-like, and quasi-bush-like trees. The patterns are determined by origins and probability ratio. The fractal dimensions have been measured a function of discharge number.
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Platinum-Cobalt alloy thin films were deposited on
$Al_2O_3$ substrates by co sputtering for RTD temperature sensors. We made Pt-Co alloy resistance patterns on$Al_2O_3$ substrate by lift-off method and investigated the physical and electrical characteristics of these films under sputtering conditions (; the input power, working vacuum), annealing conditions (; temperature, time) and also after annealing these films. After the annealing treatment at$800^{\circ}C$ for 60min, the resistivity and sheet resistivity of Pt-Co thin films was$0.0302{\mu}{\Omega}{\cdot}cm$ and$0.1{\Omega}/{\square}$ , respectively, and the TCR value of Pt-Co RTD was$3600ppm/^{\circ}C$ in the temperature range of$25{\sim}400^{\circ}C$ . These results indicate that Pt-Co thin films have potential for the excellent RTD temperature sensors. -
$(Pb_{1-x}La_x)Ti_{1-x/4}O_3$ (x=0, 0.02, 0.04, 0.06, 0.08) ceramic thin films were fabricated by Sol-Gel method. A stock solution of (Pb,La)$TiO_3$ with excess Pb 10mol% was made and spin-coated on the Pt/Ti/$SiO_2$ /Si substrate at 4000rpm for 30 seconds. Coated specimens were dried on the hot-plate at$350^{\circ}C$ for 10 min and sintered at$500{\sim}750^{\circ}C$ for 1 hour. The dielectric constant, remanent polarization and coercive field of the PLT(6 at.%) thin films sintered at$650^{\circ}C$ were 884,$13.95{\mu}C/cm^2$ and 8.7kV/cm, respectively. Pyroelectric coefficient, figure of merit of pyroelectric current, voltage responsivity and detectivity of PLT(6at.%) thin films were$3.2{\times}10^{-8}\;C/cm^2K$ ,$1.02{\times}10^{-8}\;C{\cdot}cm/J$ ,$2.9{\times}10^{-11}\;C{\cdot}cm/J$ ,$0.29{\times}10^{-8}\;C{\cdot}cm/J$ , respectively. -
In this study, Sol-Gel derived
$Ba_{0.7}Sr_{0.3}TiO_3$ (BST(70/30)) thin films were investigated. The stock solution of BST were fabricated and spin-coated on the Pt/Ti/$SiO_2$ /Si and ITO/glass substrates. The coated specimen were dried at$300^{\circ}C$ and finally annealed at$650{\sim}750^{\circ}C$ . To analyse crystallization condition and microstructural morphology for different substrates, XRD, and SEM analysis were processed. In the BST(70/30) composition. dielectric constant and loss characteristics measured at 1kHz were 173, 0.01% for Pt/Ti/$SiO_2$ /Si substrates and 181, 0.019% for ITO/glass substrates, respectively. -
The MRI Magnet is a most practical application of NbTi superconductor. In this paper, we present the main research results on superconducting wires for MRI magnet which we have developed. Cu/NbTi superconducting wires were fabricated by repeat of cold working and heat-treating process after that billets were extruded. We investigated the relation of superconductivities of wires and heat treatment condition. The correlation between cross section shape of wires and work inhomogeneity of NbTi rods was investigated by microscopic observation. The more repeatation number of cold working and heat-treating process, the higher critical current is achieved.
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This paper dealt with the surface aging characteristics of silicone rubber used as the surface material of outdoor polymer insulators under accelerated aging condition. There are many aging factors in natural environment. In this paper, the silicone rubber were accelerated to evaluate their performance against salt fog, that is, they were dipped in pure water and salt water under boiling condition. Then, contact angle and SEM(Scanning Electron Microscope) were used to estimate surface hydrophobicity, and dielectric loss(
$tan{\delta}$ ) and surface leakage current were measured to observe the electrical characteristics. -
We investigated the tracking and erosion resistance of the silicone rubber by Inclined-Plane Method. And, with the variation of the accelerated conditions such as the applied voltage and composition of contaminant, the change of the tracking characteristics according to such conditions was evaluated. The leakage current significantly increases with the increasing voltage, but the weight loss remains almost the same. The voltage above 5.0 kV isn't recommended because tracking breakdown occurs as fast as it does without erosion, and the typical discharge waveform was the form of rectifying wave.
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The main fault in this interface is that power cable insulating materials are mainly composed of a double layered structure, XLPE/EPDM laminates in cable joint. In this paper, we instituted the interface of normal and degassed XLPE/EPDM and then investigated the breakdown and conduction characteristics as a function of heat treatment time. The results showed that conduction and breakdown strength was influenced by volatile crosslinking by-products which remained inside the insulating material during the production of XLPE and EPDM, especially during heat treatment process. And micro voids and surface roughness also influenced the conduction current and breakdown strength.
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Property of insulation of electric machine is severely affected by process of electrical tree growing. Partial discharges(PD) have been used to determine degradation of insulations. In this paper, PD quantities detected and analyzed are PD magnitudes, repetition rates, phase angle distribution of PD pulses, and wavelet transformation. The wavelet transformation is an extended method of fourier transformation. The fourier transformation is a powerful tool for signal analysis, but it can't include informations for time. However the wavelet transformation analysis can include on the informations of time and frequencies at the same time. This paper discusses correlation between process of electrical tree growing and characteristics of PD in LDPE specimens.
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Piezoelectric characteristics of lead zirconate(PZ)-lead titanate(PT)-lead manganese antimony(PMS) ceramics with the various changes of calcination temperature in PMS were prepared. The range of their sintering temperature was from
$1100^{\circ}C$ to$1250^{\circ}C$ . The electro-mechanical properties of PZ-PT-PMS ceramics such as piezoelectric constant, electro-mechanical coupling coefficient, and mechanical quality factor are measured as a function of the calcination temperature of PMS. As increasing the calcination temperature of PMS mechanical quality factor is increased. -
In this paper, we have investigated the characteristics of electrical conduction and photoconduction in LDPE. The electrical conduction characteristics of LDPE have been investigated at electric fields of 50 to 500 kV/cm and at temperatures of 25,
$50^{\circ}C$ . The photoconduction in LDPE induced by vacuum ultraviolet light irradiation have been investigated at electric fields 100, 200 kV/cm and at temperatures of 25,$50^{\circ}C$ . -
Recently lots of study on EL have been performed by other researcher. Organic multilayer system of TPD/
$Alq3$ and Rhodamine 101 perchrolate/Alq3/ was constructed on ITO and finally Al as cathodic electrode. The thickness of emitting layer was$150{\AA}$ and device was fabricated by changing amount of dopant. AFM image for each surface morphology and EL spectra using fluoromax-2 was investigated. Electrical and emission properties of EL device was dependent on deposition method and condition. -
In this paper, poly (N-(2-4-imidazolyl) ethyl) maleimide-alt-1-octadecene (IMI-O) polymer which can complex metal ion was used to confirm the possibility of molecular device made by Langmuir-Blodgett method. Metal/Insulator/Metal (MIM) device was fabricated for investigation of electric properties. In the
${\pi}$ -A isotherm, surface pressure at collapse point was different as to the molecular weight of metal ion complexed respectively, In I-V characteristics, currents of MiM devices were different at the same voltage. It was thought that phenomena was occurred by interaction between function group and metal ion. -
In this paper, we measured the impedence |Z| and phase angle
$\theta$ using the Impedence Analyzer (Hp 4192A). When frequency is varied to produce resonance, the curves(admittance diagram) are obtained. The resonant frequency is obtained also. We analyzed the operating characteristics of quartz crystal coated with sensitive LB films. That is the size of circle in the admittance diagram is decreased as to coat sensitive LB films on the quartz crystal. The resonant frequency and resistance is changed with coating on the surface. -
We deposited maleate copolymer films by using Langmuir-Blodgrtt(LB) method. The deposition status of LB films were verified by the measurement of capacitance which was increased with the number of layers. And, we have investigated anisotropy electrical conduction characteristics of maleate copolymer LB films by I-V measurement for perpendicular direction and horizontal direction.
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As device size shrinks, contamination will increasingly affect the reliability and yield of device. Therefore, contaminants must be removed from the surfaces of Si wafers prior to each process. But it becomes out increasingly difficult to clean silicon surfaces with finer patterns by the conventional wet treatment because of the viscosity and surface tension of solutions. Hence, a damage less dry cleaning process is needed for the silicon surfaces. For the removal of Si native oxide by UV-enhanced dry cleaning.
$F_2$ gas and$F_2/H_2$ mixed gas were applied. As a result of analysis, UV-enhnaced$F_2/H_2$ treatment is more suitable than UV-enhanced$F_2$ treatment for removal of native oxide on the surfaces of Si wafers. -
We prepared polyimide film by electrophoretic deposition onto glass film as a sensing materials of humidity, and treated with plasma discharging as a function of discharging power to improve performance of the sensor. Then evaluated the characteristics of polyimide on humidity.
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In this paper, the streaming electrification phenomena of insulating oil by metal filters and the charge elimination method were investigated. When BTA and surfactant is molten in insulating oil, BTA appear the prevention of electrification from about 5ppm and surfactant (SP-S10, SP-S30) appear the prevention of electrification from about 20ppm. BTA increase the conductivity of insulating oil but surfactant and antioxidant(DBPC) isn't affect that.
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In this study, the dielectric properties of
$Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$ Ceramics have been investigated as a addition of the amount of$MnO_2(0{\leq}x{\leq}0.9wt%)$ . The Temperature-dependant dielectric characteristics of 0.9PMN-0.1PT relaxor ferroelectric system were improved by enhencing the extent of the diffuse phase transition(DPT). The maximum dielectric permittivity decreased by substitution$MnO_2$ and the dielectric loss decreased with increasing$MnO_2$ substitution amount. It is expected decreasing in inner heat energy for temperature with increasing$MnO_2$ substitution. -
A study on the fabrication and characteristics of plasma Polymerized hexamethyldisiloxane thin filmsPlasma polymerized thin films were fabricated by interelectrode capacitively coupled type apparatus. FT-IR analyses indicated that the thin film spectra are composed not only of the corresponding monomer bands but also of several new bands. Relative dielectric constant and dielectric loss tangent of thin films fabricated in the discharge power of 90[W] showed
$3.212{\sim}3.805$ and$0.0026{\sim}0.0451$ in alternating frequency of$10^3{\sim}10^6$ [Hz]. Contact angle measurement indicated that cross-link of the films is increased with the discharge power. -
In this work, properties of FRP insulation materials by thermal-accelerated degradation were investigated. Usually, most degradations cause the hydrophilic to decrease the contact angle and surface properties. But, in this work on thermal-degradated FRP, we can confirm the introduction of hydrophobic properties by cross-linking and the ablation of small-molecules rather than chain scission and oxidation. Hydrophobic introduction in thermal-degradated FRP caused the increase of electrical insulation on treated FRP surface. But, Tensile strength decreased steeply on FRP being exposed higher temperature.
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We investigated microhardness, friction, wear and wettability of polyimide for finding out the influence of ion implantation on surface properties. For increasing doses microhardness increased. A reduction of the friction coefficient was most cases correlated with a reduction of wear. The contact angles of water for
$B^+$ ,$N^+$ implanted polyimide decreased from$76^{\circ}$ to zero, as the fluences increased energy of 50, 200 keV. -
In this study, the
$\beta$ -Polyvinylidene fluoride($\beta$ -PVDF) organic thin films were fabricated by physical vapor deposition method as one of the dry-processing methods and applying electric field during the vapor deposition. When the substrate temperature is$80^{\circ}C$ , the PVDF organic thin films exhibit the characteristic absorption band of the$\beta$ forms$510cm^{-1}$ ,$602cm^{-1}$ and$1273cm^{-1}$ , and the fraction of$\beta$ form crystals in the total crystalline content was 95%. The molecular structure of PVDF organic thin films were transformed from$\alpha$ to$\beta$ form with increasing of applied electric field and the control of substrate temperature. -
In this paper, thin films of PI were fabricated VDPM of dry processes which are easy to control the film's thickness and hard to pollute due to volatile solvents. From FT-IR, PAA thin films fabricated by VDP were changed to PI thin films by thermal curing. From AFM and ellipsometer experimental, the higher curing temperature is, the films thickness decreases and reflectance increases. Therefore, PI could be fabricated stable by increasing curing temperature.
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The thin films were obtained by plasma polymerization of phenyl isothiocyanate. Polymerizations were carried out in rf(13.56[MHz]) glow discharge generated in an inter-electrode capacitively coupled gas flow system. It was found that this monomer produces uniform films with a wide range of thicknesses, from hundreds of nanometers to tens of micrometers. The deposition rate appeared to be dependent on the substrate distance from the monomer inlet. The IR data revealed significant decrease in -NCS groups content in the polymer as compared with the monomer spectrum and indicated for the appearance of new absorption bands corresponding to the -CN and C-H aliphatic groups. The soluble fraction by GC was found to be composed of numerous low molecular-weight compounds.
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We have investigated the influence of Ca addition in the characteristics of the modified
$BaTiO_3$ system. The specimens were fabricated with variations of Ca addition between 0mol% and 20mol%, and sintered in the$1350^{\circ}C$ . It show that PTC effect was decreased with the increasing Ca mol% from 0 to 15 mol% and, In the analysis of SEM., the grain sizes were small with increasing Ca mol%. -
Electroluminescence(EL)devices based on organic thin layers have attracted lot of interests because of their possible application as large-area light-emitting display. One of the problems of such devices is lifetime of the cell, where the degradation of the cell is partially due to the crystalliyzation of organic layers. In large part, this problem can be solved by using a multilayer device structure prepared by vapor deposition technique. In this study, blue lightemitting multilayer organic electroluminescence devices were fabricated using Poly (9-vinyl-carbazole) (PVK) and 2-(4'-tert-butylpheny])-5-(4"-bis-phenyl)1,3,4-oxadiazole (PBD) as hole trasport and electron transport material, respectively, where tris(8-hydroxyquinolinate) aluminum (Alq3) was used as a luminescenct material. A cell structure of glass substrate/indume-tin-oxide(ITO)/PVK/
$Alq_3$ /PBD/Mg:In was employed. -
In this paper, we developed newer cooling system which has better efficiency and make smaller pollution than older cooling system compressor type by using TEC Module. And then we investigated application of Peltier Effect cooling technology applied to the cold water dispenser.
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Characteristics of thermal degradation on cure conditions of DGEBA/MDA/GN system were investigated. Epoxy resin system was degradated in one stage. The activation energy of DGEBA/MDA/GN system had the lowest value in the cure time of 1.0 hr at
$80^{\circ}C$ before at$150^{\circ}C$ for 1.0 hr and it increased with the pre-cure time at$80^{\circ}C$ . -
Kim, D.K.;Jeon, J.B.;Park, C.B.;Song, M.J.;Kang, Y.C.;Park, H.A.;Soo, B.M.;Kim, T.W.;Kang, D.Y. 1573
Thin films of$BaTiO_3$ system were prepared by radio frequency (rf)/dc magnetron sputtering method. We have investigated crystal structure, surface morphology and PTCR(positive-temperature coefficient of resistance) characteristics of the specimen depending on second heat - treatment temperatures. Scanning electron microscope(SEM) image of$BaTiO_3$ thin films shows that the specimen heat treated in between 900 and 1100[$^{\circ}C$ ] shows a grain growth. At 1100[$^{\circ}C$ ], the specimen stops grain-growing and becomes a crystal. A resistivity-temperature characteristics of the specimen depends on the doping concentrations of Mn. -
We have studied the effect of the rubbing fabric for liquid crystal alignment and pretilt angle generation in nematic liquid crystals (NLC), 4-cyano-4-n-penthylbiphenyl (5CB), on rubbed polyimide (PI) surfaces. The pretilt angle of 5CB for nylon and rayon fabric is larger than that of cotton fabric in weak rubbing on rubbed PI surfaces. We conclude that the pretilt angle of 5CB is strongly related to the rubbing fabrics on rubbed PI surfaces.
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We investigated the effect of polarity of polyimide(PI) film in amorphous (a) - twisted nematic (TN) - liquid crystal display(LCD) for response time and viewing angle. We found that the domain size of a-TN-LCD on PI film with high polarity is smaller then medium polarity. It is considered that the electro-optical characteristics are strongly dependent on this domain in a-TN-LCD. We observed the response time of a-TN-LCD on PI film with high polarity is slow as comparing to PI film with medium polarity. We suggest that the response time of a-TN-LCD is attributed surface effect between the LCs and the substrates.
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We investigated the transcription of liquid crystal (LC) alignment method by using memory effect of nematic (N) LC on polyimide (PI) surface with side chain as for non-rubbing alignment techniques. That the monodomain alignment of aligned NLC is observed by polarizing microscope textures in the cells on PI surface with side chain, We obtained that the pretilt angle of NLC are generated about 3.7 degree on PI surface. We suggest that the LC alignment by using transcription aligngnment method is attributed to memory effect of NLC on PI surface.
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We investigated the generation of high pretilt angle for nematic liquid crystal (NLC) in the cell with slanted non-polarized ultraviolet (UV) light irradiation on two kinds of the polyimide (PI) film. It was shown that the monodomain alignment in NLC is obtained in the cell with slanted non-polarized UV light irradiation on PI surface. The pretilt angle of NLC is generated about 3 degrees in the cell with slanted non-polarized UV light irradiation with 70 degrees on PI surface without side chain. But, the pretilt angle of NLC is generated about 1 degree in the cell with slanted non-polarized UV light irradiation with 80 degrees on PI surface with side chain. We consider that the pretilt angle generation in NLC is attributted to anisotropic dispersion force between the LC molecular and the PI surface.
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The viewing angle characteristics of amorphous(a)-twisted nematic(TN)-liquid crystal display (LCD) on poly(vinyl)cinnamate (PVC) surfaces with photo polymerrization were investigated. It was found that the threshold voltage increases with increasing the polymerization of PVC surfaces. That the domain size of a-TN-LCD is affected by the surface crystallization with increasing the photo polymerization of the photo-alignment film. We observed that the viewing angle of a-TN-LCD increased with increasing the photo polymerization on PVC surfaces. Finally, we consider that the viewing angle of a-TN-LCD on PVC surfaces is large compared to a-TN-LCD on polyimide(PI) surface.
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The purpose of this study is to research and develop
$Li_xV_3O_8$ composite cathode for lithium polymer battery. We investigated electrochemical, interfacial properties and charge/discharge cycling of$Li_xV_3O_8$ /SPE/Li cell. The radius of semicircle associated with the interfacial resistance of$Li_xV_3O_8$ /SPE/Li cell increased very slowly during discharge process from 100% SOC to 90% SOC. And then the cell resistance was increased at discharge process from 10% SOC to 0% SOC. The discharge capacity based on$Li_xV_3O_8$ was 212mAh/g at 15th cycle. The$Li_xV_3O_8$ /SPE/Li cell has a good properties. -
$LiMn_2O_4$ is prepared by reacting stoichiometric mixture of LiOH$H_2O$ and$MnO_2$ (mole ratio 1 : 2) and calcinating at$800^{\circ}C$ for 24h, 36h, 48h, 60h and 72h. At X-ray diffraction, cathode active materials calcined at$800^{\circ}C$ for 36h. (111)/(311) peak ratio was 0.37. It was that crystal structure is formed very well. In the result of charge/discharge test, when heated at$800^{\circ}C$ for 36h, charge/discharge characteristics of$LiMn_2O_4$ is the best and Super-s-black sort of conductive agent showed well property. Also, AC impedance creased gradually during cycling and stabilized after 10cycle. -
Disordered carbon materials for anode of lithium rechargeable batteries were showed much larger reversible capacity than graphite. In this paper, we studied the electrochemical characteristics of PPP-based carbon, one of the disordered carbon, as adding with different amount of graphite. PPP-based carbon with 30wt% of graphite showed large reversible capacity,
${\sim}286mAh/g$ , irreversible capacity${\sim}299mAh/g$ , and small hysteresis between discharge and charge in carbon/Li cell. -
We have studied microstructure of carbn fiber and graphite using scanning electron microscope, x-ray diffractommetry and x-ray photoelectron spectroscopy. According to the results, intercalation of lithium ion affected formation of film on carbon surface and changed structural parameter. Also, we found that film on carbon surface included lithium ion. And, the results of XPS indicated that surface of lithiated carbon materials existed P and F consisting electrolyte. Thus, We expected electrolyte cointercalated with lithium.
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$LiNiO_2$ is prepared by heating LiOH$H_2O$ and$Ni(OH)_2$ (mole ratio 1:1). In this study, we investigated X-ray diffraction, and charge/discharge property heat treatment condition and conductive agent sort and volume of$LiNiO_2$ prepared at various temperature and time. All$LiNiO_2$ prepared at this study showed hexagonal structure. In charge/discharge capacities, heated at$O_2$ than air and$750^{\circ}C$ than$700^{\circ}C$ , specific capacity is higher. Therefore, when preliminary heat at$650^{\circ}C$ $O_2$ and heat at$750^{\circ}C$ carried out, charge/discharge property is best. -
We have synthesized PPP from benzen by chemical reaction. And then disordered carbon materials were obtained by heating-treating PPP in a nitrogen atmosphere for 1, 4, 8 and 12 hour at
$700^{\circ}C$ . The carbon prepared by heat treatment showed a broad x-ray diffraction peak around$2{\theta}=20^{\circ}$ having a property of disordered carbon. Carbon electrodes were charged and discharged at a current density of$0.25mA/cm^2$ . In the result, PPP-based carbon obtained at$700^{\circ}C$ for 8h showed 605mAh/g of first discharge capacity and had a small hysteresis characteristic. -
We fabricated five type of electric double layer capacitor(EDLC) with extremely stable activated carbon as a positive and negative electrodes. The electrodes consisted of activated carbon and several different conductor layers on aluminium foil. Cyclic voltammogram of activated carbon electrodes at scan rate 5mV/sec was reversable redox reaction. The discharge capacity of activated carbon-KS 6 composite electrode was higher than that of activated carbon electrode without KS 6.
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고분자 절연재료의 결함에 의하여 발생하는 부분방전은 고분자 재료의 화학적, 전기적 열화를 가져오며 때로는 전기 트리로 성장하여 재료의 절연파괴에 이르게 하기도 한다. 따라서 부분 방전 현상의 메카니즘 뿐만 아니라 측정법에 대한 많은 연구들이 있었으나 부분방전 열화가 고분자 재료에 미치는 열화과정에 대하여서는 명확한 메카니즘이 보고되지 않았다. 본 논문에서는 부분방전에 의한 고분자 절연재료 내의 공간전하 축적 현상에 대하여 연구하였다. 고분자 재료로는 현재 전력용 케이블에 주로 사용되고 있는 가교 폴리에틸렌(XLPE)를 사용하였으며, 1kHz의 주파수로6kV, 8kV, 10kv 및 11kV로 수시간 부분방전을 발생시킨 후 펄스정전응력법(PEA)으로 공간전하를 측정하였다. 실험결과 부분방전에 의하여 고분자 재료 내에 이종공간전하의 주입이 확인되었으며 따라서 부분방전에 의하여 고분자 재료가 열화되며 이러한 열화에 의한 전자의 방출율의 변화와 같은 고분자 표면의 상태 변화에 의하여 부분방전의 패턴에 지배적인 영향을 미친다. 이러한 공간전하의 축적에 의하여 부분방전 현상에 미치는 영향은 추후 보고할 예정이다.
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절연재료로서 널리 쓰이는 XLPE(Crosslinked Polyethylene)의 경우, 내부에 발생하는 수트리에 의해 절연체로서의 성능 및 내구성이 많은 영향을 받게 된다. 이에 대한 연구가 진행되어 왔지만 수트리 발생과 진행에 관한 메커니즘은 아직까지 정확하게 알려지지 않은 상태이다. 이 논문에서는 몇 가지의 수트리 억제 컴파운드를 선정하여 시간과 온도에 따른 수트리 발생을 관찰하고, 컴파운드 내의 공간전하 및 전도전류가 수트리 억제에 미치는 영향을 조사하였다. 수트리가속을 위하여 주파수가속열화 방법을 사용하고 온도와 시간에 따른 발생 및 진전을 관찰하였다. 실험에서는 압축성형된 평판형 시편을 사용하였으며 상부전극으로는
$AgNO_3$ 수용액을, 하부전극으로는 금속전극을 사용하였다. 그리고 컴파운드 내부의 공간전하 분포 및 전도전류 측정을 하기위해 PEA(Pulsed Electro Acoustic) 방법을 이용하였다. -
A GaAs schottky diode with taper field plate is proposed to increase breakdown voltage. Breakdown voltage is calculated by device simulator MEDICI. The GaAs schottky diode with taper gate which has
$5.7^{\circ}$ taper angle have shown 45% increase in the breakdown voltage compared with conventional field plate GaAs schottky diode. -
The breakdown voltage of SOI RESURF (REduce SURface Field) diode using a SIPOS (Semi Insulating POlycrystalline Silicon) layer is verified in terms of n-drift layer length and surface oxide thickness by device simulator MEDICI, and compared with conventional SOI RESURF diode. Increasing the n-drift layer length, the breakdown voltage of SOI RESURF diode using the SIPOS layer have increased and saturated at
$8{\mu}m$ . And it has decreased with increasing the surface oxide thickness. -
In this paper, a new PD measurement technique of pulse superposition method was proposed in order to investigate both PD mechanism and phase related PD patterns. From the experimental results, we could find that the polarity and the phase angle of the superposed pulse take great effects on PD characteristics and these method make it possible to get the physical information which statistical approach can not give. We could conclude that the changes of PD characteristics in the void surrounded by polymers may be attributed to the injection of charge carriers thereby formation of space charge in the surface and/or the bulk of the polymer.
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엑시머 레미저를 이용한 다결정 실리콘막과 게이트 절연막 사이의 계면 거칠기를 개선하기 위해 변형핀 방법의 레이저 어닐링으로 다결정 실리콘 박막 트랜지스터를 제작하였다. SEM(scanning electron microscope)으로 활성층과 게이트 절연층과의 표면 이미지를 관찰한 결과 기존의 레이저 어닐링 결정화에 의한 것보다 계면 거칠기 정도가 상당히 줄었음을 관찰 하였다. 이렇게 개선된 계면 거칠기가 다결정 박막 트랜 지스터의 성능에 미치는 효과를 분석하기 위해 기존의 방법으로 제작된 소자와 계면 거칠기를 줄인 소자의 여러 가지 전기적 변수들(문턱 전압 기울기, 문턱 전압, 누설 전류)을 비교해 보았다. 우리는 또한 계면 거칠기와 다결정 박막 트랜지스터 소자의 상관 관계를 보기 위해 컴퓨터 시뮬레이션도 함께 병행하였다. 시뮬레이션을 통해 거친 계면 부근의 전계 집중 효과 같은 것으로 인해 소자의 성능이 저하된다는 것을 알 수 있었다.
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We have investigated activation phenomena of implanted ions on silicon wafers using microwave(2.45GHz). It is found that the higher concentration of impurities makes the better activation effects by microwave annealing. We have exposed poly-Si TFTs by microwave in order to anneal and improved the device performance. Microwave activates source/drain ions and lowers the contact resistance so that the current of the poly-Si TFTs increases. In addition, the leakage current of hydrogen passivated poly-Si TFTs is decreased after microwave annealing, due to the diffusion of hydrogen ions and curing the defects in the poly-Si active channel.
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For AMLCD pixel switching device, poly-Si TFT has the advantage of high field effect mobility over a-Si TFT. However, it also has some disadvantage such as large leakage current and more masking steps. We propose a new Inverse Staggered poly-Si TFT with a-Si offset. We have fabricated the new device and verified high ON/OFF current ratio. The device has lower leakage current level than the conventional Inverse Staggered poly-Si TFT and the same number of masking steps compared with conventional a-Si TFT's.