• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.85-88
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• 2000

FRP has been used very much as high strength core materials for insulators because of its high strength and good insulation properties. In this study cantilever, tension and torsion stress were simulation along to the unidirection glass fiber. In addition, FRP was made by pultrusion method. This paper proposed the procedure of the finite element model updating and pretest using the commercial finite element code MSC. Nastran. To enhance the efficiency of experimental modal analysis, we proposed the process which is the selection of the locations and the number of measurement points for pre-test.

• Electrical & Electronic Materials
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• v.10 no.1
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• pp.61-67
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• 1997

We have studied dielectric properties of sol-gel derived tantalum oxide thin films as the insulators. As the sample is annealed from 300.deg. C to 700.deg. C, it is found amorphous below 600.deg. C and crystalline over it. Dielectric constant is maximum(18.6) when Ta$_{2}$O$_{5}$ film was annealed at 400.deg. C. It is found that dielectric strength in Ta$_{2}$O$_{5}$ film annealed at 400.deg. C (1.5MV/cm) increases and then decreases over annealed at 500.deg. C. This phenomenon was attributed to pinhole effect and crystallization. The de conduction properties can be interpreted by Poole-Frenkel effect.ect.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.467-470
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• 2000

This paper present the result of the investigation, electric properties of outdoor insulators with the difference of contaminated condition. In general, the humidity and the amount of soluble salts such as NaCl, MgCl$_2$are the most dominant factor. A mini-fog chamber with transparent acryl and the standard contamination solution with kaoline was used. The kaoline was applied with sprayer to get the specific ESDD and NSDD value, then the specimen was dried and installed horizontally. And to measure the leakage current and the ambient condition, such as relative humidity and temperature, a DAS system was developed with LabView. From the result, we could know the influence of contaminated condition. Contaminated area and pattern has a close relationship with the electrical properties of outdoor insulator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05a
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• pp.23-28
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• 2000

Insulator systems using resin casting apparatus are useful to realize the high capacity, small size, and combined electric power equipments, and are expected to bring various advantages. In Korea, epoxy resin molded apparatus have been restricted to indoor uses till now. On the other hand, in Europe, molded insulators and transformers and so forth have been practically used since the former half of 1960's. Recently, investigation on epoxy resin materials and molded apparatus for outdoor use have ben intensively carried out. Probably, this is because electric power outdoor apparatus such as distribution transformer can be given multi-functions by using outdoor epoxy resin compound This study describes the trend on the development of epoxy mold transformers, and important technologies applied for outdoor use.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1349-1350
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• 2006

FRP has been used much for core materials of insulator. FRP consists of fiber and plastics(resin and binder). The fiber contributes strength to FRP. The fiber orientation in FRP has a great effect on the strength of FRP because the strength of FRP mainly depends on the strength of fiber. The direction of applied stress of FRP is different from the kinds of insulators. In this study, inner part of FRP rod was made unidirectionally by pultrusion method and outer part of FRP rod was made by filament winding method. Compressive strength and stress of FRP rods were simulated according to the winding orientation of glass fiber. Simulated value and real evaluated compressive strength were compared each other.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1525-1526
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• 2006

Electrical current always travels through the minimum resistance path. In this paper, we are studied on the direction and formation of carbonized conductive path according to surface leakage between electrodes. The analysis of characteristics of the arc discharge as surface is broken down between exposed live parts. Using the HSIS(high speed imaging system, 100,000fps, redlake ltd., USA), it took photographs by arc growth mechanism occurred in on/off surge, ground fault and discharge between electrodes. Therefore, it recommended for results of technology development and application such as theoretic verification of an arc direction and economic security according to a technology about connecting arc generation in surfaces of insulators. Hereafter, it expected effects that application of energy utility technology through the arc control.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2220-2222
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• 2005

Epoxy Insualtion spacers for supporting the conductors and partitioning the sections in $SF_6$ Gas insulated Switchgear(GIS), require higher electrical, Thermal and mechanical reliability with other principal components in GIS to be operated without any failure in use. In this paper, we describe the results of the performance evaluation of electrical and mechanical properties for extra high-voltage GIS according to KEPCO spec. and the requirements of the insulators for GIS specified by IEC 62271-203(2004).

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2037-2039
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• 2005

2004년도 36,0001bs 볼소켓형 국산 애자에 대하여 알루미나(alumina) 첨가량의 변화에 따른 국산 2001년산 및 외국산 2000년산 자기애자의 특성 분석을 실시하였다. 그 결과 2001년도 자기애자의 알루미나 첨가량을 17%로 하고 2004년도 알루미나 첨가량이 20%로 하였을 경우 자기 애자의 기계적 특성은 10% 정도 향상되었다. 그리고 2001년도에 제조한 애자의 자기 상대밀도는 이론밀도의 96%에 도달하였으나 2004년도에 제조한 애자의 상대 밀도는 이론밀도의 98%에 도달하였으며, 애자의 균일성을 나타내는 Qs 값은 5.01로 높게 나타났다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.153-156
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• 2000

To reduce the maintenance expense, and the possibility of electric outage and accident, we should optimize the outdoor insulation system. And for the optimization, accurate measurement for the degree of contamination with climatic conditions, such as wind, rain, and drought, should be carried. However the classical measuring method, brush wiping, has some problems in the aspect of man power, reliability, and expense. In this paper, we propose two type apparatus, which could detect the degree of contamination on insulators in outdoor insulation system, such as transmission and distribution line insulator and bushing. One use the leakage current, and the other use the oscillating frequency to check the degree of contamination. To avoid the oxidation of electrode AC source, and the low degree of contamination was applied. From the result of this investigation we could get the good relationship between the degree of contamination and the leakage current and oscillating frequency

• 연구논문집
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• s.24
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• pp.81-96
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• 1994

To investigate failure mechanisms observed in carbon-phenolic thermal insulators, differential equations which govern the decomposition process in a deformable anisotropic porous solid are derived for three-dimensional axisymmetric constructions. The governing equations not only couple the material deformation with pore pressure, but also couple pressure and temperature, which means that heat convected by the pyrolysis gases is properly accounted for. Then the Bubnov-Galerkin finite element method is applied to these equations to transform them into a semidescrete finite element system. A thermal insulation liner in the cowl region under typical operating conditions is analyzed to find a mechanism for plylift. The results from the structural analysis show across-ply failure in the cowl zone. The mechanism for plylift is hypothesized as a sequential procedure : 1) the across-ply failure which is the precursor to plylift and 2) the local fiber buckling caused by generation of excessive in-plane compressive stress. To prevent plylift, the across-ply stress can be reduced by using appropriate material ply angles in cowl zone design.