• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.791-798
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• 2004

압밀현상에 따른 포화된 점토의 유전특성과 전기비저항 특성을 분석하기 위해서 전기적 측정이 가능한 Oedometer 압밀시험기를 준비하였다. 포화된 카올리나이트 시료에 대해서 실시한 압밀시험 결과, 압밀현상에 따른 직류 전기비저항과 1MHz (저주파대) 유전상수는 간극수의 소산에 따라 선형으로 증가하는 경향을 보였다. 점토의 전기비저항 특성은 압밀 현상 시 발생하는 흙의 함수량 및 공극비의 감소, 즉 흙의 구조적 특성에 의하여 변하는 것으로 나타났다. 반면, 포화된 점토의 유전 특징은 불포화 점토와는 달리 흙 표면에서 발생하는 분극현상에 의하여 크게 영향을 받는 것으로 나타났다.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.828-831
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• 2005

Producing high transparency dielectric is still one of the most important subjects in the PDP process for improving luminous efficiency. It has been reported by many workers that transparency is improved by controlling the composition of the frit, the frit size and distribution, and the firing atmosphere. To understand the mechanism of discoloration of frit, $Bi_2O_3$ and $B_2O_3$ glasses were used for a leaching test using water and alcohol solution in milling. As a result, the frit prepared by wet milling had lower chemical durability than that prepared by dry milling. The leached layer around the frit showed high stability for heat treatment because the frit surface was covered with hydroxides or hydrates which was resulted from a reaction between the frit and the solution during milling.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1430-1432
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• 2001

In this paper, 200-class insulation system for form-wound stator coils is designed for form-wound stator coils is designed for AC traction driven with VVVF inverter. Model coils are made to embody all essential elements representing a winding insulation system and structure. Acceleration degradation for model coils is applied exposure to heat(235$^{\circ}C$). In order to investigate the condition of the coils and to determine their insulation reliability, high voltage test and the dielectric properties such as dielectric loss and capacitance are performed. Also, partial discharge measurement is investigated for internal defects.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1649-1651
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• 2001

The effect of ribbed spacers having metallic particle attached to the post-type spacer on dielectric breakdown phenomena has been investigated using electric field analysis for imaginary streamer process and a breakdown experiment. It was described that the electric field analysis and the dielectric breakdown test were performed on the case that the particle was attached to the various position of the ribbed spacer having various shapes. As a result, the breakdown voltage of the spacer with two ribs was highest, and it was varied by the length and the thickness of the rib. Especially, in case of the rib with round edge, the breakdown voltage was higher than that with rectangular edge, which complied with the result through the field analysis.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1541-1543
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• 1996

This paper describes the results of characteristics on the tracking resistance, hydrophobicity and dielectric properties of silicone rubbers used for outdoor insulation with ozone ageing. The tracking and ozone ageing tests for this purpose ware made in according to IEC 587 and ASTM D 1149, respectively. Additionally, we investigated the surface structure of the silicone rubbers with FT-IR and SEM. From the test results, it is proven that the higher the degree of ozon ageing, the worse tracking characteristics.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1597-1599
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• 1996

In this study, we investigated the electrical characteristics such as tracking resistance, dielectric constant, insulating resistance, and arc resistance, of silicone rubber for outdoor use, and, focused on the tracking resistance. In the Inclined Plane Test, two kind of the contamination solutions were used, and their phenomena were observed. The average leakage current and the tracking breakdown time decreased, and erosion rate increased, using anionic surfactant added contaminant solution. The dielectric constant and dissipation factor were increased with increasing temperature.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.382-385
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• 1995

Electrical properties such as tracking resistance, dielectric constant, $tan\delta$, and volume resistivity, and mechanical properties such as tensile, and strength, and % elongation were measured with the alumina trihydrate filled with EPDM. The results were dicussed in terms of the effect of hydroxyl group. The test results show that the tracking resistance of EPDM improves with the increase in ATH content, whereas volume resistivity, dielectric constant, $tan\delta$ decrease wi th increasing ATH content due to polar nature of ATH. In the charge accumulation characteristics, the homocharge is formed in pure EPDM, and as the ATH content increases in the EPDM compound, the amount of homocharge decrease.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.444-447
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• 2003

All objects with some temperature above absolute zero radiate in the infrared. The intensity of the infrared radiated from a object defends on the condition and temperature on the surface of the one. The present, these techniques are frequently adopted into diagnosis for electricity equipments. Simply, however, the applied techniques are passive thermal testing for the detection of loosened terminals and overcurrent. In this paper, a infrared thermal imager was applied to high voltage windings of cast resin transformers, and the accumulated value of the result temperatures was used for evaluating remained lifetime of them. At each aging level, dielectric loss tangent test was carried out. The results offered capabilities for deciding the condition of the transformers suffering difficulties to diagnose.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.203-207
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• 2002

In order to evaluate the aging of mineral oil immersed distribution transformers, it gathered some insulation oil in over loaded and long time(exceed their service life, 13yrs.) aged transformers in the field, we measured moisture content, acid number, dielectric strength of the oil as defined in KS C 2101 standard. And also, it had been measured dielectric constant, specific resistant, $tan{\delta}$ on aged transformer oil at from $10^{\circ}C$ to $130^{\circ}C$. These results are compared with a new mineral oil. From this study, it can be considered that the analysis of mineral oil may be suitable for evaluation of life expectancy in distribution transformers

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.256-259
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• 1996

In this paper, We studied polyethylene thin film to evaluate the effects of crystal structure on breakdown properties and the dielectric strength on the condition of impurity free. Bielectric strength of the finn obtained with self healing method that is able to test repeatedly on the same sample is about 3.58 MV/cm at 0.73 $\mu\textrm{m}$. The film shows outstanding crystal domain an\ulcorner crystal structure. The size of spherulites obtained reach 150-200 $\mu\textrm{m}$ in diameter.