• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1608-1610
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• 1999

To find effective diagnostic method for Transmission OF cables, various characterizations were carried such as DGA (dissolved gas analysis), water contents, total acidity and AC breakdown voltage. It was found that the result was varied by sampling and container. The results from those characterization method showed the present condition and history very well and could be used to estimate the degree of degradation of cables.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.304-309
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• 1991

We introduce the trend, of several countries, to the gas insulated transformer recently coming into the spot light by the advantages of less weight, GIS-lization, low noise level and easiness to decrease environmental pollutions, and the insulating gases. the cooling media and the insulating materials used for transformer. Hereinafter, additively the design of proto type $SF_6$ gas insulated transformer (insulation, cooling), which was developed by us(HICO) from 1987. 2 through 1990. 3, the manufacturing processes(leak protection, pressure, drying of main body), the accessories, the protective system, the cooling system, the method and the results of test and the evaluation of economics compared with conventional oil-filled transformer are represented.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.209-213
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• 2005

To enhance the reliability of distribution transformers in service and to reduce the cost of maintaining and replaceing these, the condition and life of those insulating system should be evaluated accurately and the time to replace should be determined economically. Since the transformer failures related to insulation failure indicates that the primary cause is normally mechanical failure of integrity due to loss of mechanical strength as a result of degradation, the tensile strength characteristics of paper during ageing under accelerated conditions in insulating oil and research trends for assessing the life of insulating paper were investigated.

• 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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• 2008.05a
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• pp.173-174
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• 2008

Time Domain Reflectometry(TDR) 기법을 응용하여 극초단파 대역을 포함하는 광대역 주파수범위에서 절연유의 유전율을 쉽게 측정할 수 있는 기법을 제안하였다. 수 GHz 이상의 대역에서의 절연유 유전율은 전자파를 이용한 전력용 변압기 부분방전 발생위치 추정에 필수적인 정보이나 기존의 방법으로 간단히 측정할 수 없었다. 본 기법은 동축구조에서 전자파 진행속도가 절연매질 유전율의 함수로 인가된 펄스파의 매질에 대한 동축선로에서 진행시간을 계산함으로써 유전율을 구하는 간단한 방법이다. 제안한 새로운 방법을 이용해 절연유중 1종4호 신유의 경우 광대역에서의 유전율은 2.1임을 알 수 있었다.

• Corrosion Science and Technology
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• v.6 no.6
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• pp.308-310
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• 2007

The owner of underground metallic structures (gas pipeline, oil pipeline, water pipeline, etc) has a burden of responsibility for the corrosion protection in order to prevent big accidents like gas explosion, soil pollution, leakage and so on. So far, Cathodic Protection(CP) technology have been implemented for protection of underground systems. The stray current from DC subway system in Korea has affected the cathodic protection (CP) design of the buried pipelines adjacent to the railroads. In this aspect, KERI has developed a various mitigation method, drainage system through steel bar under the rail, a stray current gathering mesh system, insulation method between yard and main line, distributed ICCP(Impressed Current Cathodic System), High speed response rectifier, restrictive drainage system, Boding ICCP system. We installed the mitigation system at the real field and test of its efficiency in Busan and Seoul, Korea. In this paper, the results of field test, especially, distributed ICCP are described.

• 전기의세계
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• v.29 no.5
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• pp.315-320
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• 1980

It has been appeared and widely used today SF6 Gas Insulated Substation(Hereafter called GIS) for the power supply to the densely populated area due to the superior insulation withstand ability of SF6 Gas. And to maximize the compact effect of this substation, it is normal practice to connect underground cables. If it is possible to elieminate the redundant lightning arresters using the physical characterestics of travelling waves in underground cables, economical advantages can be obtained together with easy maintenances. It is presented in this paper the possiblity of eliminating the transformer protection lightning arresters under some conditions for the 154kV GIS's (BIL:750kV) which Korea Electric Co. plans to construct using the general purpose digital computer program.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1676-1678
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• 2001

In general, power demand is on an increasing trend as industries have made rapid strides. Power transformer is the most important equipment in substation for this reason. Transformer trobles go with blackout, expensive repair costs and huge economic losses. Therefore it is important to find the quick detection of incipient fault for the least losses. There have been gas, partial discharge, temperature, OLTC, fan and pump diagnosis for preventive techniques by present. Specially gas analysis has been adapted for a long time and proved as confident method. In this paper, we analysed the fault causes of used power transformer. The insulation faults was occupied 40% of inquired 152 faults from 1991 to 2000. This study presents the developed algorithm and expert system for finding abnormal status within transformer. We used the Element Expert tool developed Neuron DATA Inc.

• Proceedings of the KIEE Conference
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• 2000.07e
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• pp.108-112
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• 2000

The electric charge generated by flowing insulation liquid can create hazardous spark in transfer line and receiving tank etc. These electrification has generally been measured by current measurement with a ammeter connected to the receiving tank. This paper reports on the experimental result obtained by this method. As a experimental results: The injected charge value for unit volume increased in the following condition, the edge of the needle electrode was sharp, the number of needle electrode was fewer, the edge of the needle electrode was located close to the inside wall. When the charge density in the charge reducer is constant, electrode current and electrode potential by the charge injection from outside increase with increasing of oil velocity and streaming current. The electrode potential in charge reducer is made maximum value at edge point of reducer inside and minimum value at center line of charge reducer.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.127.2-127
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• 2001

A transformer is one of the most important elements in the power network. Transformer faults could cause costly repairs and be dangerous to personnel. To avoid this, its reliable operation has great significance and, therefore, the diagnosis system of the transformer is necessitated. The dissolved gas-in-oil analysis (DGA) is the worldwide popular method of detecting faults such as a hot spot or partial discharges inside the transformer. DGA, however, is not a reliable technique to identify aging phenomena and mechanical faults including insulation failure, inter-turn short, etc. To overcome the drawbacks of DGA, the transfer function method is used to identify effectively these kinds of the mechanical faults. The transformer has a unique transfer function independent of the shape of the input waveform, which can be evaluated through sweep test. This transfer function changes by winding ...