• 대한수학회논문집
• /
• 제10권4호
• /
• pp.981-995
• /
• 1995

This paper first establishes some conditions for preconditioner under which PGCR does not break down. Next, VPGCR algorithm whose preconditioners can be easily obtained is introduced and then its breakdown and convergence properties are discussed. Lastly, implementation details of VPGCR are described and then numerical results of VPGCR with a certain criterion guaranteeing no breakdown are compared with those of restarted GMRES.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 C
• /
• pp.1901-1903
• /
• 1996

In This paper, to understand statistical properties of breakdown voltage, the experiment is performed on four gaps of different electrode area, ranging from $17.44[cm^2]$ to $1809.5[cm^2]$, in $SF_6$ gas. Statictcial property of breakdown is confirmed Weibull distribution and as area of electrode is increased, breakdown voltage is decreased and converged constant value $E_0$.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1992년도 하계학술대회 논문집 B
• /
• pp.883-885
• /
• 1992

DC dielectric breakdown properties of epoxy composites with various additives rates and curing conditions were investigated at the temperature range from 20[$^{\circ}C$] to 180[$^{\circ}C$]. At low temperature an improvement of the characteristics is observed due to curing agents. The additions of filter is lower the temperature dependences of the breakdown strength. Samples treated with silan have a higher breakdown strength than non-treating filled samples.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
• /
• pp.556-560
• /
• 1987

To enhance the breakdown properties of low voltage-oriented ZnO varistor, the samples were fabricated with the amounts of si-oxides and the sintering conditions. And then, to lower the breakdown voltage the $TiO_2$-added samples were fabricated. We investigated the nonlinear exponent, the nonlinear resistance and the V-I characteristics of samples. And we discussed with microstructures by use of SEM and the position of Si by EDS. Si-oxides, especially, largely enhanced the nonlinear exponent. In this case optimum sintering condition was $1200-1250^{\circ}C$-1hr and $TiO_2$ addition lowered the breakdown voltage.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1996년도 추계학술대회 논문집
• /
• pp.260-264
• /
• 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[%].

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.460-461
• /
• 2007

In this paper, we studied the properties of a cable insulate capacity between surfaces with the variation of the interfacial breakdown. As a function of silicon oil, the variation of pressure and interfacial roughness were investigated. The insulate trouble of a power cable is out of the interfacial parts, which breakdown the insulate breakdown capacity in a power cable. In this study, the analysis of electric field and the phenomenon of interfacial breakdown were improved by increased interfacial pressure, decreased surface roughness, and oil. And It was shown that interfacial breakdown LSR-XLPE insulators is higher that of EPDM-XLPE.

• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 2002년도 학술대회 논문집
• /
• pp.185-188
• /
• 2002

In the design of superconducting power equipments such as transformer, cable and fault current limit, knowledge of the dielectric behavior of both liquid and gaseous at very low temperatures is very importance. Especially, Electrical properties of liquid nitrogen($LN_{2}$) and gaseous nitrogen($GN_{2}$) have become of great interest again since the discovery of high temperature superconductors. However, many sources of $LN_{2}$and $GN_{2}$ problems in the test of pancake coil model arising form the deficiency of insulation data. Therefore, this paper describes the results of an experimental study on the ac breakdown voltage($V_{B}$) properties of $LN_2$ and Air under the electrode of simulated HTS pancake coil. The ac breakdown voltage of $GN_{2}$ have been measured by pancake coil-pancake coil gaps over the temperature range of 293 K to 77 K.

• 전기학회논문지
• /
• 제67권10호
• /
• pp.1330-1337
• /
• 2018

In this study, 40, 50, 60, and 70 wt% filler dispersed samples were prepared for the current GIS Spacer or environmentally friendly GIS. In the AC electrical breakdown, EMSC and EMAC decreased with increasing filler content, and EMSC showed better breakdown strength than EMAC. The mechanical properties such as tensile strength and flexural strength of EMSC and EMAC were also increased with increasing filler content. In addition, EMSC results in better mechanical properties than EMAC. The reason for this is considered to be one in which the influence of the interface is important.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 D
• /
• pp.1428-1431
• /
• 1998

The polypropylene has been known to have higher melting temperature than polyethylene, and good mechanical properties. This paper introduces the experement result of dielectric breakdown properties to a polypropylene with a crystal structure. According to the experement, breakdown voltage is incresed when a thickness of thin film thinned. Spherulites of PP film prepared by annealing is larger than that of PE.

• 한국전기전자재료학회논문지
• /
• 제22권3호
• /
• pp.210-217
• /
• 2009

Insulated methods of compact bus duct has been applied a way of coating Epoxy powder. The problem which is caused by degradation during operation is very important in severe environment. Therefore, this study compared and verified many kind of properties ; electrical breakdown by thermal and water aging, v-t characteristic, arc discharge, mechanical properties, bending test and cross cut. Sample D was stable before the $T_g$ to be about $7{\sim}10 %$ decrease in the breakdown test according to temperature change. In case of V-t and arc discharge, it had been kept up suitable characteristic. Also, in case of electrical and mechanical characteristic, both sample D and A have excellent capacity.