• Transactions on Electrical and Electronic Materials
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• v.14 no.6
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• pp.324-328
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• 2013

An alternating current (AC) electrical treeing phenomena in an epoxy system with low chlorine BDGE (1,4-butanediol diglycidyl ether) was studied in a needle-plate electrode arrangement. To measure the treeing propagation rate and breakdown time, a constant AC of 10 kV with three different electric field frequencies (60, 500, and 1,000 Hz) was applied to the needle-plate electrode specimen at $130^{\circ}C$ in aninsulating oil bath. The treeing propagation rate of the DGEBA/high-chlorine BDGE system was higher than that of the DGEBA/low-chlorine BDGE system and the breakdown time of the system with high-chlorine BDGE was lower than that of the system with low-chlorine BDGE. These results implied that chlorine had a negative effect on the electrical insulation property of the epoxy system. As the electric field frequency increased, the treeing propagation rate increased and the breakdown time decreased.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1216-1217
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• 2008

A description is given of impregnated silicone rubber used in accessories for application on outdoor termination (EB-A). We examines the effects of swelling and mechanical/electrical characteristics for impregnated silicone rubber to develop slip on type sleeve of silicone material. There are semi-conductive silicone rubber and insulation silicone rubber. This examination is monitored as a function of the viscosity and temperature of oil during 30hr. We measure elongation at breakdown and AC breakdown strength and volume resistivities of the oil-impregnated silicone rubbers. The measured values are compared to initial value as function of stress relief cone.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.49-51
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• 1993

Recently, use of High Voltage cables with extruded insualtion is increasing. Generally this polymeric insuation contains residual stresses. The effect of internal residual stresses is the so-called shrink-back of the insulation. If not controlled, these stresses may lead to problems during installation and service of the cables. Therefore in this paper, the definition and cause of shrinkage are described and furthermore the influence due to shrink-back at cable joint-box.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.127-127
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• 2010

This study describes the optimal design of shield to improve the insulation performance of vacuum interrupter(VI). Axi-symmetric finite element routine including floating boundary condition for shields was applied to analyze electric potential and field distribution in VI. A ($\mu-\lambda$) Evolution Strategy(ES) is employed as optimization method. Three design variables of shield are selected for minimizing the maximum electric field strength in VI. Finally, optimal solution for shield is obtained and compared with the result of the prototype.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.149-150
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• 2005

According to the trend for electric power equipment of high capacity and reduction of its size, the needs for the new high performance electric equipments become more and more important. On of the possible solution is high temperature superconducting (HTS) power application. Following the successful development of practical HTS wires, there have been renewed activities in developing superconducting power equipment. HTS equipments have to be operated in a coolant such as liquid nitrogen ($LN_2$) or cooled by conduction-cooling method such as using Gifford-McMahon (G-M) cryocooler to maintain the temperature below critical level. In this paper, the dielectric strength of unfilled epoxy and filled epoxy in $LN_2$ was analyzed. The filled epoxy composite not only compensates for this fragile property but enhances its dielectric strength.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.260-264
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• 1996

In this study, the dieiectric breakdown of epoxy composites used for transformers was experimented and then its data were simulated by Weibull distribution probability . As a result. first of all, speaking of dielectric breakdown properties, the more hardener increased the stronger breakdown strength at low temperature, and the breakdown strength of specimens because it is believed that the adding filler farms interface and charge is accumulated in it, therefore the molecular motility is raised, the electric field is concentrated, and the acceleration of electron and the growth of electron avalanche are early accomplished. In the case of filled specimens with treating silane, the breakdown strength become much higher since the suggests that silane coupling agent improves interfacial combination and relays electric field concentration. Finally, from the analysis 7f weibull distribution. it was confirmed that as the allowed breakdown probability was given by 0.11[%].

• Fire Science and Engineering
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• v.31 no.1
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• pp.42-49
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• 2017

The present article reports the tracking characteristics of phenolic resin insulation material due to accelerated degradation. For assessing insulation degradation of the phenolic resin insulation material, experiment samples with equivalent years of 0, 10, 20, 30, and 40 years were produced by conducting accelerated degradation experiments using Arrhenius equation. Subsequently, tracking experiments according to KS C IEC 60112 standard were conducted for the experiment samples that were previously subjected to accelerated degradation. According to the measured results for tracking characteristics of phenolic resin subjected to accelerated degradation, upon dropping of 0.1% ammonium chloride, the risks were shown to increase by 1.38 times for the equivalent life of 10 years; 1.45 times for 20 years; 1.62 times for 30 years; and 1.94 times for 40 years based on the equivalent life of 0 year. Upon dropping of 0.01% ammonium chloride, the risks were shown to increase by 1.39 times for the equivalent life of 10 years; 1.52 times for 20 years; 1.99 times for 30 years; and 5.30 times for 40 years. According to the experimental results, the tracking risk was shown to be higher for longer-duration insulation degradation due to aging. In particular, the risk was observed to be greatly increased in the case of the equivalent life of 40 years. Therefore, it is proposed that the occurrence possibility and the risk of electric fires could be minimized through institutional preparation of recommended replacement period by considering risks such as insulation degradation, etc. due to aging.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.341-347
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• 2009

As a right-of-way security for the high power transmission line tower construction is becoming more and more difficult, the friendly environmental compact tower design is required. For a proper insulation for the compact tower, the polymer material are being tried. Some countries has already adapted, in the various polymer application and management data, polymer arm insulator to the transmission tower, and shown a stable operation. However, in our country, the polymer arm insulator has left much to be desired in the installation on the transmission line tower. But polymer material has been developed by high strength and technology and is expected to be used in various electric equipments. The polymer arm insulator is a one of good electric insulation materials to expand the power supply capacity in the rapid power demand increasement In this research, the new polymer am insulator is designed and its electric specifications are analyzed. Its mechanical specifications is verified through the field test on the compact tower which is modified by the polymer arm insulator.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.645-650
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• 2010

The continuous increase demand for electric power leads to the additional construction of transmission facilities, but it is not easy to acquire right-of-way for transmission facilities. Therefor, there is a need for compact tower that can be built on a narrow right-of-way the compact tower with polymer insulation arm is a solution. It can be upgrading conventional 154 kV transmission line voltages to 345 kV levels. However transmission voltage is increasing, environment interference (corona noise, radio interference, etc.) will occur gradually. This environment interference is depending on the electrical clearances of tower and configuration of conductors. Therefore the analysis of the factors of environmental interference is necessary in order to upgrading transmission voltage. This paper presents the design factor of a compact tower to meet the environmental interference standard.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.264-265
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• 2008

While the reliability of bulk insulation has become important particularly in multilayer boards and embedded boards, electronics are to be used under various environments such as at high temperature and in high humidity. We observed internal space charge behavior for two types of epoxy composites under dc electric fields to investigate the influence of water at high temperature. In the case of glass/epoxy specimen, homocharge is observed at water-treated specimen, and spatial oscillations become clearer in the water-treated specimens. Electric field in the vicinity of the electrodes shows the injection of homocharge. In aramid/epoxy specimens, heterocharge is observed at water-treated specimens, i.e. negative charge accumulates near the anode, while positive charge accumulates near the cathode. Electric field is enhanced just before each electrode. In order to further examine the mechanism of space charge formation, we have developed a new system that allows in situ space charge observation during ion migration tests at high temperature and high humidity. Using this in situ system.