• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.187-187
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• 2000

Properties of electrical discharge in flames are investigated by making use of the ionization cross section of air. Fames have three distictive features. They are hot, emit light and are weakly ionized. We investigate influence of these three characteristics of flames on the electrical breakdown. It is found that the breakdown electric field in flames is inversely proportional to the flame temperature, thereby easily generating plasmas in flames. A swarm of low-energy electrons in flames would allow significant population of electronically excited states of flame molecules to be formed. Therefore, the analysis shows that the electronic excitation of flame molecules may also considerably reduce the breakdown field. Plasma electrons generate atomic oxygens by the electron attachment of oxygen molecules in high-pressure flames. These oxygen atoms are the most reactive radicals in flames for material oxidation. How are you and your family in this new year\ulcorner Professor Choi! I plan to go back Korea on February 6. All my family members are fine and have good time because I am here. Once I am in Korea, I will call you. I am always grateful for your helpful hand. Thank you so much.

• 조명전기설비학회논문지
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• 제12권2호
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• pp.85-90
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• 1998

본 논문에서는 AC 전압 하에서 자유 도전성 금속이물 혼입에 의한 SF6 가스로 압축된 GIS의 절연특성에 관하여 연구하였다. GIS 내에서 자유 도전성 금속이물이 혼입되면 절연파괴 전압을 낮추는 결정적인 역할을 할 수 있으므로, 금속이물의 재질과 크기에 따른 부상전계 및 절연파괴전압을 측정하였다. 구리, 철, 알루미늄의 선형 금속이물에서의 부상전계 계산값과 측정값을 비교, 분석하였다. 압축된 $SF_6$ 가스로 절연된 동축원통전극간에 금속이물의 혼입될 경우의 절연파괴전압은 금속이물의 없을 때보다 낮게 나타났으며, 금속이물의 재질과 크기에 상당히 의존하였다. 따라서 자유도전성 금속이물은 GIS의 절연파괴 특성에 매우 중요한 요소로 작용함을 알 수 있었다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.383-386
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• 2014

The characteristics of gas free jet flows in laminar with having applied electric fields have been investigated experimentally. A single electrode configuration was adopted such that electric fields were applied directly to nozzle and thus the surrounding could be an infinite ground. The experimental results showed that breakdown point at laminar flow has been measured by varying the applied voltage and frequency of AC. The effect of applying electric fields to free jet flow in laminar was discussed in detail.

• 한국전기전자재료학회논문지
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• 제15권11호
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• pp.985-990
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• 2002

The electrical breakdown characteristics of liquid nitrogen(LN$\sub$2/) were studied under simulated quenching conditions for application of HTS apparatus. The experimental results for various quenching condition revealed that the breakdown voltage of LN$\sub$2/ with bubble flow velocity and gap spacing. In the case, breakdown voltage decreases gradually with the bubble velocity. When it is bubble velocity from 0 to 1 $\ell$ /min, breakdown voltage rapidly decreases but decreases from 2 $\ell$/min to 10 $\ell$/min slowly. The breakdown voltage for vertical electrode arrangement is higher than that for horizontal electrode arrangement. Also, it did a electric field and potential distribution interpreting at the liquid nitrogen when the bubble existed. The plots of equipotential lines for three cases are also shown.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.359-362
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• 1998

Electrical breakdown characteristics of liquid nitrogen(LNd used as both coolant and insulator for high $T_c$ superconductor system is very important. This paper presents dynamic breakdown characteristics of liquid nitrogen by quench penomena of thermal bubble under high electric field. As the result, the breakdown mechanism of $LN_2$ depends on thermal bubble effect. The breakdown voltage decreases slightly with increasing heating. In the Electrode arrangement, electrical breakdown voltage of horizontal arrangement appears lower than that of vertical arrangement.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.460-461
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• 2007

In this paper, we studied the properties of a cable insulate capacity between surfaces with the variation of the interfacial breakdown. As a function of silicon oil, the variation of pressure and interfacial roughness were investigated. The insulate trouble of a power cable is out of the interfacial parts, which breakdown the insulate breakdown capacity in a power cable. In this study, the analysis of electric field and the phenomenon of interfacial breakdown were improved by increased interfacial pressure, decreased surface roughness, and oil. And It was shown that interfacial breakdown LSR-XLPE insulators is higher that of EPDM-XLPE.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.462-463
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• 2007

SF6 widely used as insulating gas is rising as the environment problem. For decreasing this greenhouse gas, electrical breakdown characteristics of composite insulation composed of epoxy resins with N2, air are studied in non-uniform field. The gap of needle to plane was 3mm, 5mm. The pressure of air, nitrogen was varied within the range of 0.1~0.6MPa. The thickness of a needle is 1mm and the curvature radius of the end of needle is 100um. The diameter of a plane made of the stainless steel is 50mm. As a result of the experiment, the breakdown voltage is increased about 3 times when epoxy resins is composited. The thickness of epoxy resins filled opposite to electrode concentrated electric field weakly influences on breakdown voltage.

• 조명전기설비학회논문지
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• 제16권1호
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• pp.35-43
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• 2002

새로운 형태의 고체 상태의 대전력, 고속전자장치인 광전도 전력스위치(PCPS)의 개발과 대전력 및 고전압 상태하에서 광전도 전력스위치의 고전계 동작특성을 규명하기 위해서 많은 연구가 행해지고 있다. 그러나 표면 섬락 현상이 확실하고 효과 있는 고속, 고압스위칭 소자의 실현을 방해하고 있다. 이러한 연면방전의 물리적 현상의 명백한 이해는 새로운 기술과 소자구성을 발전시키는데 매우 중요할 뿐 아니라, 고전계·고전압에서의 동작특성을 향상시키는데 있어서도 특별한 의미를 가진다. 뿐만 아니라 고전계, 고전력 소자들을 안전하게 동작할 수 있게 하기 위해서도 필요하다. 연면방전 및 표면 절연파괴현상은 반도체 벌크 파괴 전계보다 훨씬 낮은 전계에서 적용되어 파괴된 모든 소자들에서 발생하기 때문에 이러한 문제를 해결하는 매우 실용적인 방법이 소자의 표면을 절연물로 페시베이션하는 것이다. 페시베이션된 소자들은 고전계에서 언페시페이션된 소자에 비해 매우 좋은 동작특성을 나타내므로, 본 논문에서는 페시베이션된 소자와 언페시베이션된 소자간의 I-E특성과 파괴 메커니즘을 규명하고 더 나아가 다중 페시베이션에 대한 몇몇 특성 값을 제시한다.

• 한국전기전자재료학회논문지
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• 제20권9호
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• pp.793-797
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• 2007

In this paper, the long time breakdown characteristic of the epoxy composite, which is widely used in the insulation system for high voltage application, was estimated with Weibull distribution. In the procedure of the estimation, the short time breakdown characteristics for the epoxy composite specimens, which were made with the variation of hardener and/or filler, were tested firstly. Then the long time voltage-to-time test was implemented. Finally, the long time breakdown voltage of each specimen was estimated with the parameters obtained from the statistical treatment with Weibull distribution. Base on the results, it has been found that the optimal weight ratio of epoxy resin/hardener/filler that has the excellent long time breakdown characteristic was 100/100/65. It was due to the silane treatment which relieves the electric field at the interface between filler and epoxy.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권2호
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• pp.67-73
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• 2003

The algorithm (or calculating the base-collector breakdown voltage of NPN BJT(Bipolar Junction Transistor) for integrated circuits is Proposed. The method for calculating the electric field using the solution of Poisson's equation is presented and the method for calculating the breakdown voltage using the integration of ionization coefficients is presented. The base-collector breakdown voltage of NPN BJT using 20V process obtained from the proposed method shows an averaged relative error of 8.0% compared with the measured data and the base-collector breakdown voltage of NPN BJT using 30V process shows an averaged relative error of 4.3% compared with the measured data