• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1407-1409
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• 1998

It was investigated that space charge characteristics and Breakdown characteristics of XLPE/EPDM laminates as a function of interfacial condition. When the chemical A was pasted in laminate interface, there was little space charge in XLPE/EPDM interface and it was shown that breakdown strength of XLPE/EPDM laminate was influenced by laminate condition.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 추계학술대회 논문집
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• pp.122-128
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• 1994

Studies on treeing phenomena have depended on the visual measurement using optical microscope. In the visual measurement, it is difficult to analyze the treeing in real time because voltages are applied discontinuously and impossible to calculate the deterioated area by treeing. Only tree type and length are studied. In this paper, image processing is introduced and voltages are applied continuously. The tree length and area are calculated in real time from tree inception to breakdown. Growing characteristics about tree types are compared for the normalized breakdown time.

• 대한안전경영과학회지
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• 제3권4호
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• pp.45-52
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• 2001

In order to Investigate water tree degradation behavior on XLPE cable, direct voltage of 200 to 800V has been applied to the material at 5$0^{\circ}C$~10$0^{\circ}C$, and the water tree property has been correlated with voltage and temperature. The leakage current was increase as temperature increased and the Ohm's law was generally satisfied in this experiment though some experimental errors were found. The leakage current was decreased and reached to the stable state with time. It was also shown that the time for the stabilization of leakage current was lessened as voltage increased

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 춘계학술대회논문집
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• pp.57-60
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• 2005

This paper describes the experimental results of the pre-breakdown phenomena in $SF_6/CO_2$ mixtures under non-uniform electric fields caused by positive and negative lightning negative voltages. $SF_6/CO_2$ mixtures have an advantage of an environmental aspect and cost reduction, and safety aspects. In order to analyze the pre-breakdown processes in $SF_6/CO_2$ mixtures stressed by impulse voltages, pre-breakdown current and luminous signals were measured by a shunt and a photo-multiplier tube, respectively. Dielectric strengthes of $SF_6/CO_2$ mixtures were investigated. Additionally, characteristics of discharge channels were observed by high speed cameras and the physical properties were discussed. The pre-breakdown propagates with a stepwise process. The in to breakdown from the corona onset point in positive polarity was shorter than that in negative polarity. The time intervals of positive leaders are shorter than those of negative leaders, and the path of positive leader channel is zigzag.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.605-608
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• 1993

Breakdown characteristics of a small rod-to-rod microairgap has been studied for obtain an optimum breakdown voltage and an airgap spacing to be used as an emission control means by the electrical arc-burning unburnt carbon particulates exhausted from a power station burner. It is found that the breakdown voltage at the rod-to-rod airgap spacing in the rang of $1{\sim}100{\mu}m$ decreased with decrease in the rod-to-rod airgap spacing. And there were no minimum breakdown voltage on a $V_b$-Pd characteristics which is known as the minimum voltage in Paschen's law in air atmosphere. Breakdown voltages of the airgap at the constant airgap spacing were $V_{b-dc}>V_{b-ac}>V_{b-pulse}$, and it was lowest for the pulse voltage applied. As a result, it is found that a pulse power was one of effective power compared with dc or ac to be used as such an unburnt carbon particulate emission control means and the airgap spacing became to several tens ${\mu}m$, then the breakdown voltages were down to several handreds voltages.

• 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.

• 전기학회논문지
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• 제57권2호
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• pp.245-251
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• 2008

Although many studies have been carried out about binary gas mixtures with $SF_6$, few studies were presented about breakdown characteristics of $SF_6/CF_4$ mixtures. At present study the breakdown characteristics of $SF_6/CF_4$ mixtures in non-uniform field was performed. The experiments were carried out under AC voltage and standard lightning impulse(SLI) voltage. Breakdown characteristics were investigated for $SF_6/CF_4$ mixtures when AC voltages and standard lighting impulse voltage was applied in a needle-plane. The needle-plane electrode whose gap distance was 3 mm were used in a test chamber. $SF_6/CF_4$ mixtures contained from 0 to 100% $SF_6$ and the experimental gas pressure ranged from 0.1 to 0.5 MPa. The breakdown characteristics of $SF_6/CF_4$ mixtures in non-uniform field may be influenced by defects like needle-shaped protrusions. In case of slowly rising SLI voltage and AC voltage it is enhanced by corona-stabilization. This phenomena caused by the ion drift during streamer development and the resulting space-charge is investigated. In non-uniform field under negative SLI voltage the breakdown voltage was increase linearly but under positive SLI voltage the breakdown voltage increase non-linearly. The breakdown voltage in needle-plane electrode displayed N shape characteristics for increasing the content of $SF_6$ at AC voltage. $SF_6/CF_4$ mixture has good dielectric strength and arc-extinguishing properties than pure SF6. This paper presents experimental results on breakdown characteristics for various mixtures of $SF_6/CF_4$ at practical pressures. We could make an environment friendly gas insulation material with maintaining dielectric strength by combing $SF_6\;and\;CF_4$ which generates a lower lever of the global warming effect.

• 전기의세계
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• 제24권5호
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• pp.82-90
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• 1975

This study investigated the deterioration phenomena of the Polyethylene surface contaminated with organic(Saccharose) or inorganic(NaCl) matters through electrical and optical experiments. And also these experimental results relatively well coincided with which was treated by theoretical process. On the electrical experiment, relation between electric field intensity in corona discharge and time reached to the breakdown, and relation between total amount of charges discharged and increment of applied voltage were investigated. On the optical experiment, discharge time dependence of surface deterioration rate and process of surface deterioration in the X-ray diffraction pattern were investigated. It was concluded that chemical effects by the corona discharge deteriorated insulation characteristics of Polyethylene surface.

• 조명전기설비학회논문지
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• 제22권2호
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• pp.128-133
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• 2008

이 논문은 반구형 수조에 설치되어 있는 침전극과 구형전극에 표준뇌임펄스전압을 인가하였을 때 나타나는 수중 방전현상과 절연파괴특성을 나타낸다. 이 논문의 목적은 뇌서지에 대한 과도접지임피던스와 관련된 기본적인 특성을 파악하는데 있다. 인가전압의 극성과 물의 저항률에 따른 방전광을 촬영하였고 절연파괴전압의 의존성을 측정하였다. 침전극과 구형전극의 끝단에서 스트리머코로나가 발생하였고 접지된 수조를 향하여 단계적으로 진전하였다. 저항률에 따른 절연파괴전압은 V자 형태를 나타내며, 구형전극의 절연파괴전압-시간곡선이침전극보다 높게 나타났다.

• 한국자동차공학회논문집
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• 제5권1호
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• pp.27-37
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• 1997

Internal combustion engine is the main source of environmental pollutants and therefore better technology is required to reduce harmful elements from the exhaust gases all over the world. Especially, harmful elements from the exhaust gases are caused by incomplete combustion of mixture inside the engine cylinder and this abnormal combustion like misfire or partial burning is the direct cause of the air pollution and engine performance degradation. the object of this research is to detect abnormal combustion like misfire and to keep the engine performance in the optimal operating state. Development of a new system therefore could be applied to a real car. To realize this, the spark-plug in a conventional ignition system is used as a misfire detection sensor and breakdown voltage is analyzed. In this research, bias voltage(about 3kV) was applied to the electrodes of spark-plug and breakdown voltage signal is obtained. This breakdown voltage signal is analyzed and found that a combustion phenomena in engine cylinder has close relationship with harmonic coefficient K which was introduced in this research. Newly developed combustion diagnostic method( breakdown voltage signal analysis) from this research can be used for the combustion diagnostic and combustion control system in an real car.