• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.54-57
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• 1997

The electrical properties such as space charge accumulation, dielectric breakdown and water treeing of acrylic acid-grafted polyethylene (PE-g-AA) and n-butyl acrylate-grafted polyethylene (PE-g-nBA) were investigated. In PE-g-AA, heterocharge founded in LDPE decreased with the increase of AA graft ratio and changed to the homocharge formation above 0.lwt% due to the introduction of carbonyls. Conduction currents decreased with the increase of AA graft ratio. AC breakdown strength increased and water treeing length decreased with the increase of graft ratio in PE-g-AA and PE-g-nBA.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1580-1582
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• 1994

In this study, when AC voltage is applied to block type treeing specimen which is fabricated with polyethylene which dielectric characteristics is excellent, from initial tree to final breakdown, Using acoustic emission method. we take statistically on parameter, which is skewness. We experimented on quenching condition and illustrated skewness locus plane so that studied interrelation of life expectation and parameter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.483-486
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• 1999

The treeing inhibitors of barbituric acid derivatives and azocompounds effects on the electrical properties of crosslinked low density polyethylene were investigated. The electrical treeing parameters for tree inception voltage, AC breakdown strength. volume resistivity, capacitance and dissipation factor at 1Mz and thermoluminescence measurements were discussed. From the results, 4- (4-nitrophenylazo) resorcinol among the treeing inhibitors was shown good insulation characteristics.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.840-849
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• 2013

This paper presents a statistical approach to analyze electrical tree inception voltage, electrical tree breakdown voltage and tree breakdown time of unsaturated polyester resin subjected to AC voltage. The aim of this work was to show that Weibull and lognormal distribution may not be the most suitable distributions for analysis of electrical treeing data. In this paper, an investigation of statistical distributions of electrical tree inception voltage, electrical tree breakdown voltage and breakdown time data was performed on 108 leaf-like specimen samples. Revelations from the test results showed that Johnson SB distribution is the best fit for electrical tree inception voltage and tree breakdown time data while electrical tree breakdown voltage data is best suited with Wakeby distribution. The fitting step was performed by means of Anderson-Darling (AD) Goodness-of-fit test (GOF). Based on the fitting results of tree inception voltage, tree breakdown time and tree breakdown voltage data, Johnson SB and Wakeby exhibit the lowest error value respectively compared to Weibull and lognormal.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.969-972
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• 1992

It is shown that the ac breakdown strength, treeing phenomena, oxidation level, and crystallinity of unaged and aged distribution CV cables vary with XLPE insulations (characterizing anti-oxidation) and curing process. The maximum size of bow-tie tree in insulation influenced on the decrease of ac breakdown strength and the increase of oxidation level and crystallinity of XLPE according to aging time lead to increase the size and density of bow-tie trees.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.12
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• pp.1060-1069
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• 1998

Electrical properties such as space charge accumulation and water tree length and physical properties such as tensile strength, elongation and degree of crosslinked polyethylene (XLPE)/ethylene n-butyl acrylate copolymer (EnBA) blends were investigated. It was found that electrical properties such as water tree length grown at a specific condition and AC breakdown strength are improved by blending the XLPE with EnBA. The EnBA having higher nBA content showed the better electrical properties in XLPE/EnBA blends. A further improvement of these properties was achieved when a small amount of crosslinking coagent was used in the preparation of XLPE/EnBA blends.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1992-1994
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• 1999

Dicumyl peroxide (DCP) is used for crosslinking agent in general. And the correlation between polyethylene and DCP is significant in particular radiation environment. On this paper, The effects on $Co^{60}{\gamma}$-ray irradiation of polyethylene doped dicumyl peroxide(DCP) were investigated. We experimented on electrical properties as following; electrical tree inception and growing type for applying AC step voltage, AC breakdown strength, volume resistivity, capacitance and dissipation factor at high frequency as increasing dosage. Also, chemical analysis was performed TGA, gel content.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.427-430
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• 1991

In this study, in order to observe treeing of prebreakdown phenomena, time variation of acoustic emission properties due to initiation and propagation of tree in LDPE was investigated under AC voltage. The experimental results were as following, pulse number and average amplitude of AE were increased along with near breakdown rather than tree initiation, also, according to increasing of applied voltage, tree propagation was blunted, while pulse number and average amplitude of AE was promoted. In each applied voltage, ${\phi}-a$ distributions during propagation of tree were changed to special patterns, skewness S and kurtosis K reflected well time variation of ${\phi}-a$ distribution patterns. It is thought that initiation and propagation state of tree can be easily monitored, so long as time variation of pulse number and average amplitude of AE, skewness Sand kurtosis K of ${\phi}-a$ distribution are always monitored.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1758-1760
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• 1997

Automatic detection system to detect acoustic emission pulse and fractal dimension were developed, to observe tree deterioration phenomena in LDPE. The purpose of our work are to use acoustic emission system and fractal dimension and to investigate the treeing phenomena in polymeric insulation under applied AC voltage 11[kV] with an artificial needle-shaped void(1.5[mm]) using the above system. We analyzed and phase angle-acoustic emission pulse amplitude-deterioration time ($\Phi$-AEA-t) pattern and phase angle-acoustic emission pulse number-deterioration time($\Phi$-AEN-t) pattern using statistical operators such as skewness, fractal dimension. In this paper show that the correlation of $\Phi$-AEA-t, $\Phi$-AEN-t, fractal dimension using regression analysis by the method of least squares can be used to predict the breakdown just before the breakdown occurs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.278-282
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• 1996

Electrical properties of acrylic acid and n-butyl acrylate grafted polyethylene were investicated. Charge accumulation characterist-ics of acrylic acid grafted PE are changed by graft ratio, but it remains not changed in n-butyl acrylate grafted PE. It was also observed that anti-treeing and AC breakdown strength of grafted PE were increased due to the graft ratio. The change of electrical properties of grafted PE were attributed to the polar group introduced by the graft reaction.