• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.485-487
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• 2004

High-voltage gas-insulated circuit-breaker must interrupt short-circuit current successfully when breakdown occurs in electric power system. Among many test-duties, Basic Terminal fault T100a(BTF T100a) is the one of the severest duties because of its high DC component of short-circuit current. In this paper, we developed 245kV 50kA gas circuit breaker using control circuits to reduce DC component while interrupting short-circuit current, then got good performance through high-power tests in Korea Electrotechnology Research Institute(KERI) and KEMA

• 대한방사선기술학회지:방사선기술과학
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• 제2권1호
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• pp.71-83
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• 1979

Not only the insulating oil used for extra high voltage and high capacity transformer has a lot of possibilites of a corona discharge in oil, but the oil is easily degraded by a response of light oxidization. This study is either to classfy, with priority given to a transformer oil produced in Korea belonging to, the insulating oil No. 2, the sample irradiated the ultraviolet rays, treated a corona discharge in oil by a high voltage DC source and done nothing, or to measure the characteristics of breakdown, V-i, I-t and electrode material. The obtained results can be summarized as followings: (1) Unless the sample is contacted with the air, on the process to irradiate the ultraviolet rays, the sample less influence on the changes of the electric characteristics. At the same time, if the sample is contacted with the air and irradiated the ultraviolet rays, the sample shows a remarkable changes of the electric characteristics, and a declined breakdown strength. This tells us that the influence of the light irradiation must be considered as a primary factor of degrading the insulating oil. (2) In the oil treated by a corona discharge, breakdown voltage is declined more than in the oil not to be treated with it. This means that the degradation of the insulating oil is getting increased by a corona discharge in oil. (3) It shows that the increase of conducting current has little to do with breakdown voltage. (4) The conducting current depending on the electrode materials can be put in order by value as Al>Cu>Fe. This is due to the differences of the work function of each metals, and an chemical reaction with the insulating oil. These result can be a great help in verifying the degradation progress of the insulating oil and furnish a new technical information to the manufacturers of the insulating oil and electrical equipment designers and operators. Besides, this study would be helpful to improve the electrical characteristics of the insulating oil produced in Korea.

• JSTS:Journal of Semiconductor Technology and Science
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• 제3권2호
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• pp.63-68
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• 2003

The DC and RF characteristics of $In_{0.5}Ga_{0.5}P/In_{0.22}Ga_{0.78}As/GaAs$ p-HEMTs with a gate oxide layer of various thicknesses ($50{\;}{\AA},{\;}300{\;}{\AA}$) were investigated and compared with those of a Schottky-gate p-HEMT without the gate oxide layer. A prominent improvement in the breakdown voltage characteristics were observed for a p-HEMT having a gate oxide layer, which was implemented by using a liquid phase oxidation technique. The on-state breakdown voltage of the p-HEMT having the oxide layer of $50{\;}{\AA}$was ~2.3 times greater than that of a Schottky-gate p-HEMT. However, the p-HEMT having the gate oxide layer of $300{\;}{\AA}$ suffered from a poor gate-control capability due to the drain induced barrier lowering (DIBL) resulting from the thick gate oxide inspite of the lower gate leakage current and the higher on-state breakdown voltage. The results for a primitive p-HEMT having the gate oxide layer without any optimization of the structure and the process indicate the potential of p-HEMT having the gate oxide layer for high-power applications.

• 한국재료학회지
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• 제3권3호
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• pp.310-315
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• 1993

P-type(100)Si Wafer 위에 400$\AA$의 Ta를 증착하여 열산화법으로 ${Ta_2}{O_5}$박막을 형성시킴 후 RTA후처리를 통하여 절연파괴전장 특성 개선을 이루고자 하였다. 유전상수에 미치는 RTA후처리의 영향은 미약하지만 절연파괴전장을 나타내었으나 결정화 온도 이하의 RTA온도에서는 절연파괴전장이 5.4MV/cm로 RTA효과가 크게 나타났다. 이러한 RTA효과는 RTA온도 $575^{\circ}C$에서 flat band voltage shift가 RTA 시간에 따라 변화가 없는 것으로 미루어 보아 RTA효과는 계면 변화에 의한 것이 아님을 알 수 있었으며, RBS 분석을 통하여 ${Ta_2}{O_5}$1박막의 치밀화에 의한 것임을 확인할 수 있었다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권3호
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• pp.215-220
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• 1999

$SO_2$and CO gas removal characteristics of a wire-to-cylinder type nonthermal discharge plasma reactor in various applied voltage (-dc, ac, fast rising pulse and high frequency pulse) and a crossed dc magnetic field have been investigated. The experiment has been emphasized on the oxidizing characteristics of $SO_2$ and CO gas by $O_3$ and the applying of a crossed magnetic field, which would induce the cyclotronic and drift motions of electrons making the residual time longer in the removal airgap space. And it also would enhance the energy of electrons and the electrophysicochemical actions to remove the pollutant gases effectively. It is found thatthe corona onset voltage and the breakdown voltage were decreased with increasing the crossed magnetic field and decrease initial fed $SO_2$and CO concentration. As a result, a higher ozone generation and $SO_2$ and CO gas removal rate of 20[%] can be obtained with -dc, ac and fast rising pulse corona discharges in the crossed dc current-induced magnetic field. But high frequency pulse didn't show effect in applying of a crossed magnetic field.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.226-229
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• 2003

Following the successful development of practical high temperature superconducting (HTS) wires, there has been renewed activity in the development of superconducting power equipments. HTS equipments must be operated in the coolant, such as liquid nitrogen (L$N_2$) or cooled by cooler, such as GM-cryocooler to maintain the temperature below critical temperature. In this paper, dielectric strength of some insulating materials, such as epoxy, teflon, and glass fiber reinforced plastic (GFRP) in L$N_2$was measured. Surface breakdown voltage of GFRP which is basic property in design of HTS solenoid coil was measured. Epoxy is a goof insulating material but it is fragile at cryogenic temperature. The multi-layer insulating method of current lead is suggested to compensate this fragile property. It consists of teflon tape layer and epoxy layer fixed with texture. Based on these measurements, the 6.6㎸ class HTS magnet for DC reactor type high-T$_{c}$ superconducting fault current limiter (SFCL) was successfully fabricated and tested.d.

• 대한전자공학회논문지SD
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• 제46권9호
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• pp.1-6
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• 2009

본 논문에서는 음극 및 양극으로 동시에 열 방출을 수행할 수 있는 이중 방열 구조의 Gunn 다이오드를 제작하고 음극 방열 구조를 갖는 Gunn 다이오드와 그 특성 차이를 비교하였다. 제작된 다이오드의 DC 특성 측정 결과, 단일 방열 구조의 경우에는 3 V의 문턱전압과 744 mA의 최대 전류 및 4.8 V의 항복 전압 특성을 나타내었고, 이중 방열 구조 다이오드는 2.5 V의 문턱전압, 778 mA의 최대 전류 및 5 V 이상의 항복전압 특성을 나타내었다.

• 전기전자학회논문지
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• 제20권3호
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• pp.279-284
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• 2016

This paper presents a two stage L-band power amplifier realized with a $0.32{\mu}m$ Silicon-On-Insulator (SOI) CMOS technology. To overcome a low breakdown voltage limit of MOSFET, stacked-FET structures are employed, where three transistors in the first stage amplifier and four transistors in the second stage amplifier are connected in series so that their output voltage swings are added in phase. The stacked-FET structures enable the proposed amplifier to achieve a 21.5 dB small-signal gain and 15.7 dBm output 1-dB compression power at 1.9 GHz with a 122 mA DC current from a 4 V supply. The amplifier delivers a 19.7 dBm. This paper presents a two stage L-band power amplifier realized with a $0.32{\mu}m$ Silicon-On-Insulator (SOI) CMOS technology. To overcome a low breakdown voltage limit of MOSFET, stacked-FET structures are employed, where three transistors in the first stage amplifier and four transistors in the second stage amplifier are connected in series so that their output voltage swings are added in phase. The stacked-FET structures enable the proposed amplifier to achieve a 21.5 dB small-signal gain and 15.7 dBm output 1-dB compression power at 1.9 GHz with a 122 mA DC current from a 4 V supply. The amplifier delivers a 19.7 dBm saturated output power with a 16 % maximum Power Added Efficiency (PAE). A bond wire fine tuning technology enables the amplifier a 23.67 dBm saturated output power with a 20.4 % maximum PAE. The die area is $1.9mm{\times}0.6mm$.

• 한국정보통신학회논문지
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• 제8권7호
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• pp.1429-1435
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• 2004

본 논문에서는 DC 바이어스 소자와 정전파괴 보호회로를 MMIC상에 모두 내장한 완전집적화 K/Ka밴드 광대역 증폭기 MMIC를 제작하였으며, 따라서 MMTC의 동작을 위해서는 프린트기판상의 외부소자가 불필요하였다 DC 바이어스 용량성소자로서는, 소형의 SrTiO3 (STO) 커패시터를 MMIC 내부에 집적하였으며, DC feed 소자로서는 소형의 LC병렬공진회로를 집적하였다. 그리고 정전파괴방지를 위해서는 소형의 LC병렬공진 정전파괴 보호회로를 MMIC의 입출력부에 내장하였다. 정전파괴 보호회로에 의해 정전파괴전압은 10 V에서 300 V까지 개선되었다. 광대역에 걸쳐서 양호한 RF특성과 안정도를 보장하기 위해서, 프리매칭 기법과 RC병렬 안정화 회로가 이용되었다. 제작된 MMIC는 K/Ka 밴드의 광대역(17-28 GHz)에 걸쳐서 $20{\pm}2$ dB의 전력이득, $21{\pm}1.5$ dBm의 1dB 이득 압축점 (P1dB)의 양호한 RF특성을 보였다. 그리고 제작된 MMIC로부터 DC에서 동작주파수이상의 광대역에 걸쳐서 안정화 특성을 관찰 할 수 있었다. 제작된 MMIC의 면적은 $1.7{\pm}0.8$ mm2이었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1617-1620
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• 1999

In this work, the effect of blend on physical and electrical properties investigated. The two kinds of low-density polyethylene (LDPE) whose densities are evaluated at $0.9179[g/cm^3]$ and $0.9192[g/cm^3]$, respectively, were used and blended according to the different blend ratio. The LDPE with the blend ratio of 50[wt%] represented the lowest impulse breakdown strength, $F_{BImp}$ at $30[^{\circ}C]$, but the highest $F_{BImp}$ at $90[^{\circ}C]$. DC breakdown strength, $F_{BDC}$. decreased with the increase of blend ratio at $30[^{\circ}C$, but increased at $60[^{\circ}C]$. The current density decreased with a blend ratio up to 75 [wt%] at $90[^{\circ}C]$. By analyzing the diffraction patterns of XRD, we found that the LDPE with the blend ratio of 50 [wt%] represented the largest crystal size of (020) plane. We investigated the relationship between the effect of blend and electrical properties and these results are discussed.