• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1807-1809
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• 1996

The axial discharge at switching operations of EHV $SF_6$ disconnector can lead to the breakdown to the enclosure. Precursor in periphery zone leads to formation of leader over some time delay. Injected charge value depends on electric field and gap geometry. The calculation method for parameters of $SF_6$ insulation for DS in EHV-GIS is suggested by using the new criterion of leader inception in connection with periphery field nearby the boundary of streamer zone.

• 전기의세계
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• v.24 no.5
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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.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1193-1194
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• 2006

전력계통에 적용하기 위한 풍력발전시스템의 연계변압기 결선방법과 배전계통의 고장전류와의 관계를 알아보고 계통에서의 단상 고장전류 발생 시 변압기 결선 방식의 변화에 따른 simulation을 수행하고자 한다.

• 전기의세계
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• v.23 no.3
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• pp.67-69
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• 1974

The electric characteristics of all the instruments and materials used in atomic field is changed due to radiation damages by the effects of radio activities. In this study, when the condenser is radiated by Gamma-ray, variations in its electric properties have been investigated. The following results are obtained. (1) The capacitance in O.F paper condenser is exponentially increased as the quantity of irradiation by Gamma-ray is increased, but polyethylene, ceramic, chemical, neostyrene, mylar condenser are decreased. and in case of more than 10$^{7}$ of irradiation it has saturated state, (2) The breakdown voltage and the .delta. in condensers except the O.F paper condenser are exponentially increased as the quantity of irradiation by Gamma-ray is increased but in case of more than 10$^{7}$ .gamma. of irradiation it has decreased.

• Progress in Superconductivity and Cryogenics
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• v.5 no.3
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• pp.43-47
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• 2003

For an electrical insulation design of HTS cable, it is important to understand the dielectric characteristics of insulation materials in $LN_2$ and the insulation type. Generally, the electrical insulation of HTS Cable is classified into two types of the composite insulation and solid insulation type. In this research, we selected the insulation paper/$LN_2$ composite insulation type for the electric insulation of a HTS cable, and studied electric insulation characteristics of synthetic Laminated Polypropylene Paper (LPP) in liquid nitrogen ($LN_2$) for the application to high temperature superconducting (HTS) cable. Furthermore, we compared the breakdown characteristics of the butt gap and bended mini-model cable. It is necessary to understand the winding parameter of insulation paper/$LN_2$ composite insulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.588-593
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• 2007

The 600kJ class high temperature superconducting magnetic energy storage (HTS SMES) system is being developed by Korean Electrotechnology Research Institute (KERI). The system is operated in cryogenic temperature and high vacuum condition. The SMS magnet was cooled by conduction cooling method using a Gifford-McMahon cycle cryocooler. Thus, electric insulation design at cryogenic temperature and high vacuum is a key and an important element that should be established to accomplish compact design is a big advantage of HTS SMES. This paper describes the electric insulation design, fabrication and experimental results for a mini model of conduction cooled HTS SMES.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.151-154
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• 2005

In this paper the experiments of insulation characteristics by temperature change of $SF_6$ gas and liquid $SF_6$ in model GIS(Gas Insulated Switchgear) were described. From this results, the breakdown voltage was increased with a drop of temperature and an increase of the inner pressure in model GIS. The ability of insulation in liquid $SF_6$ was higher than that of the highly pressurized $SF_6$ gas. A liquid $SF_6$ discharge characteristics was caused by bubble formed evaporation of liquid $SF_6$ and bubble caused by high electric emission. It is considered that these result are fundamental data for electric insulation design of superconductor and cryogenic application machinery which will be studied and developed in the future.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.346-349
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• 1997

It is well known that water treeing is one of the main cause of breakdown in underground power cables, but water tree is not easy to observe. This aging phenomenon was resulted in effect of water and electric field and so on. In this paper, Distilled water was used as water electrode to observe the water treeing in XLPE(cross-linked polyethylene). To observe easily, sample was made of pallet types so water tree was able to show by microscope. As a result, electrical tree appears at niddle electrode tip which was concentrated electric field, but water tree was shown up different types that were appealed in total area of water electrode as well as water electrode tip.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.81-81
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• 2010

This paper presents results of experimental investigations on natural ester regarding the breakdown strength. Aging of insulating material in a pole transformer has been studied by performing accelerated thermal aging test. Sealed aging test vessels containing copper, laminated core, Krapt paper and insulating oil(Natural oil and Mineral oil) were aged at $140^{\circ}C$ for 30days. Compared to the conventional transformer oil, electric property of the natural ester fluid is excellent.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.974-979
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• 2007

From '1994 Gwacheon accident of the Electric Multiple Unit(EMU)' till '2004 Seoul subway 2 lines Guui station accident', the accident is increasing at day and the service demand of the citizen is coming to be various. But it does not deal with technical or operation side demands. There is a possibility of saying that the accident of the EMU or deficit operation is caused by the RCM. The EMU where the efficiency is good though does the time passes and it becomes old anger and does not display that efficiency not only the cause of formation accident does becomes. The breakdown about under occurring before getting up an accident, appropriately shifting the parts is to a maintenance very the pending question fact which is important is a possibility of doing. From there is by an EMU, RCM in reliability base grudge is a tool of confirms an improvement point and the place where it judges. From the research which it sees will present about technical development plan of RCM.