• Journal of the Korean Society for Precision Engineering
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• v.27 no.3
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• pp.104-110
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• 2010

Cyclic deformations of polymer foam film are simulated using the finite element method. Material of polymer foam film is polypropylene (PP). The calculated polymer foam film is micro-scale thin film has cellular structure. The polymer foam film is used in ferro-electret applications. The polymer foam film is idealized to one cell structure as lens shaped stretched truncated octahedron model. Cyclic deformation is performed by uniaxial stretching. Stretching direction is perpendicular to plane of cellular film. Various cyclic strain amplitudes, pore wall thicknesses, pore shape are investigated to find deformation tendency of cellular structure. Consequently, cellular structure has various macroscopic stresses on cyclic deformation with various pore thickness and pore shape.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.401-403
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• 1995

The degradation phenomena according to electrical stress in epoxy composites were studied. The formation of electrets were observed by appling high voltages, 22.9[kW/cm], during 5[hr] to five kinds of specimens for a given mixing rate, and then TSC(thermally stimulated current) values were measured at the temperature range of $-160\sim200[^{\circ}C]$.

• Electrical & Electronic Materials
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• v.1 no.3
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• pp.261-268
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• 1988

본 논문에서는 두께 50[.mu.m]의 미연신 .alpha.형 폴리비닐덴 후로라이드 필름을 시료로 선정, .+-.4~.+-.6[kV]사이의 코로나대전 전압을 인가하여 얻은 코로나 일렉트렛트로 부터 온도 범위 -100[.deg.C]-100[.deg.C] 사이에서 열자격전류를 측정한 결과, 저온으로 부터 .delta., ..gamma., .betha. 및 .alpha.인 4개의 TSC 피크를 얻었다. 이들 피크의 기원을 정성적으로 고찰한 결과, .delta., .gamma.피크는 비정질 영역에서 카보닐기, 주쇄 및 극성기들에 의한 쌍극자의 탈분극으로 또 70[.deg.C]부근에서 관측된 .betha.피크는 비정질 영역 또는 비정질과 결정질의 경계면에서 전극으로 부터 공간전하의 탈트랩으로 그리고 180[.deg.C]근방에서 관측된 .alpha.피크는 결정영역에 깊이 트랩된 캐이어들의 탈트랩으로 각각 피크가 나타나는 것으로 사료된다. .delta., .gamma., .betha.및 .alpha.인 4개의 TSC 피크에 대하여 초기 상승법으로 얻은 활성화 에너지는 각각 0.54[eV], 0.24[eV], 0.99[eV] 및 1.26[eV]를 얻었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.123-126
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• 2005

In this study, the Thermally Stimulated Current(TSC) of corona charged PTFE is studied and the simulation of corona charging process is also calculated by Finite Element Method. The electrets which were formed by applying high voltages (DC ${\pm}5{\sim}{\pm}8$ [kV]) to PTFE, are used to measure TSC in the temperature range of $-100{\sim}+200$ [$^{\circ}C$] and then the Finite Element Method is performed to examine corona charging process using a obtained physical constants. As a result. it is confirmed that the charging negative corona is profitable as the applications are manufactured, because the time constant of negative corona is much larger than it of positive corona. And it is attempted to estimate the corona charging process in space using simulation.

• Electrical & Electronic Materials
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• v.8 no.6
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• pp.759-767
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• 1995

This paper examines the electrical properties according to a curing time and a corona degradation in epoxy composites which are used for transformers. To consider these phenomena, the electrets were formed by appling high voltages to five kinds of specimens designed according to a constant mixing rate and then TSC(Thermally Stimulated Current) values at the temperature range of -160-200[>$^{\circ}C$] were measured from a series of experiments. The behaviour of carrier and its possible origins in epoxy composites were studied. Various effects of curing time and electric field on epoxy composites were also investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.94-98
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• 1994

In this study, the thermally stimulated current(TSC) of corona charged PTFE film was studied and the simulation of corona charging process was also calculated by finite element method. The electrets which were formed by appling high voltages(DC-5∼-8[kV]) to PTFE film were experimented to measure TSC in the temperature range of -100∼+200 [$^{\circ}C$] and then the finite element method was accomplished to examine corona charging process using a obtained physical constants. It is confirmed that the charging negative corona is profitable as the applications are manufactured because the time constant of negative corona is much larger than it of positive corona. And it is attempted to estimate the corona charging process in space using simulation.

• Proceedings of the Korean Society of Computer Information Conference
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• 2011.06a
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• pp.351-354
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• 2011

The electrical degradation phenomena of epoxy composites to be used as a molding material for transformers were studied. The electrets were first manufactured by applying high voltages to five kinds of specimens given a mixing rate, and then TSC(Thermally Stimulated Current) values at the temperature range of $-160{\sim}200[^{\circ}C]$ were measured from a series of experiments. The behaviour of carrier and its origin in epoxy composites were examined, respectively. And various effects of electrical degradation on epoxy composites were also discussed in this study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.67-70
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• 1988

In this paper, thermally stimulated currents (TSC) of corona-charged PTFE film were studied. Corona electrets which were formed by applying high voltages ${\pm}$5∼${\pm}$8[kV], to PTFE film of 100[$\mu\textrm{m}$] thickness, were experimented to measure TSC in the temperature range from -100[$^{\circ}C$] to 200[$^{\circ}C$]. As the result, four peaks of ${\gamma}$, ${\beta}$$_2$, ${\beta}$$_1$ and ${\alpha}$ were obtained at the temperature of -40[$^{\circ}C$], 30[$^{\circ}C$], 90[$^{\circ}C$] and 170[$^{\circ}C$], respectively. Speaking of the origins of these peaks, first of all, ${\gamma}$ peak is believed to show up by virtue of CF$_2$groups. B$_2$ peak seems to turn up by detrapping of the electrons which are accelerated by the corona exposure. ${\beta}$$_1$ peak looks to be ascribed to detrapping of the dipole and the trapped electron. Finally, ${\alpha}$ peak appears to result from detrapping of the electrons which are trapped in the para-crystalline region.