• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.233-234
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• 2008

We observed internal space charge behavior for two types of epoxy composites under dc electric fields to investigate the influence of water at high temperature. In the case of glass/epoxy specimen, homocharge is observed at water-treated specimen, and spatial oscillations become clearer in the water-treated specimens. Electric field in the vicinity of the electrodes shows the injection of homocharge. In aramid/epoxy specimens, heterocharge is observed at water-treated specimens, i.e. negative charge accumulates near the anode, while positive charge accumulates near the cathode. Electric field is enhanced just before each electrode. In order to further examine the mechanism of space charge formation, we have developed a new system that allows in situ space charge observation during ion migration tests at high temperature and high humidity. Using this in situ system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.219-222
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• 1998

The space charge and conduction characteristics of chemically modified vinylpyridine (VP) grafted low density polyethylene (LDPE) was investigated. VP grafted LDPE was analyzed by elemental analysis (EA) to confirm the grafting reaction. Homocharge was developed in VP grafted LDPE at low graft ratios and changed to heterocharge with increasing the content of VP. In conduction experiment, current densities of VP grafted LDPE were lower than that of LDPE and VP grafted LDPEs showed almost the same conduction characteristics as vinylpyridine graft ratio increased

• 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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• 2008.07a
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• pp.2307-2308
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• 2008

We observed internal space charge behavior for two types of epoxy composites under dc electric fields to investigate the influence of water at high temperature. In the case of glass/epoxy specimen, homocharge is observed at water-treated specimen, and spatial oscillations become clearer in the water-treated specimens. Electric field in the vicinity of the electrodes shows the injection of homocharge. In aramid/epoxy specimens, heterocharge is observed at water-treated specimens, i.e. negative charge accumulates near the anode, while positive charge accumulates near the cathode. Electric field is enhanced just before each electrode. In order to further examine the mechanism of space charge formation, we have developed a new system that allows in situ space charge observation during ion migration tests at high temperature and high humidity. Using this in situ system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.2
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• pp.127-132
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• 2002

Space charge distributions and behaviors in silane crosslinked polyethylene(SXLPE)/ crosslinked polyethylene(XLPE) laminates were investigated using a pulsed electroacoustic (PEA) method. In case of monolayer, XLPE shows heterocharge while SXLPE shows homocharge. It was observed that charges were accumulated at the interface of SXLPE/XLPE laminate when applied electric field was more than 20kV/mm. The charge profile at various temperatures was also acquired using temperature-controllable PEA system. Although applied electric field is only 8.6 kV.mm, positive interfacial charge starts to appear near 50$^{\circ}C$. It was found that the interfacial charge behavior of SXLPE/XLPE laminate under low voltage at high temperature is corresponding to that under high voltage at room temperature.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1196-1198
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• 1997

In this work, simultaneous measurement such as change distribution and electrical conduction of maleic anhydride grafted XLPE was investigated. Heterocharge was found in XLPE and it decreased with increasing MAR graft ratio in XLPE-g-MAH. Conduction currents also decreased with increasing MAR graft ratio. The relationship between the space change behavior and the electrical conduction characteristics in XLPE-g-MAH is discussed.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.1
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• pp.42-49
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• 1992

Charge accumulation characteristics in low density polyethylene (LDPE) has been discussed based upon the internal charge distrubution measured by the pulsed electroacoustic technique. When the negative voltage with respect to earth is applied to the upper electrode, the negative charges near the anode and the positive charges near the cathode are accumulated in LDPE. Also, there was an asymmetric behavior of charge accumulation exhibiting that the charge accumulation near the anode keeps increasing whereas that near the cathode increases first and then decreases. Besides, under the present test conditions the internal charge distrubution becomes stabilized eventually. When the positive voltage with respect to earth is applied to the upper electrode, on the other hand, no such asymmetric charge accumulation was found. Therefore, it can be concluded that the heterocharges are accumulated at the surface region of LDPE subjected to high do voltages and that the begavior of charge accumulation depends on the polarity of do voltage and the position of charge accumulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.536-539
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• 1999

Physical properties of glass fiber-reinforced nylon 6,6 and ionomer blends were investigated in variation of ionomer and glass fiber content. With the increase of ionomer content, tensile strength, impact strength and flexural strength decreased, whereas increasing glass fiber content, these properties were improves. Both permittivity and tan $\delta$ remain unchanged. Space charge distribution was investigated by PEA (Pulsed electroacoustic) method. Heterocharge was found in nylon 6,6 and 히ass fiber composites, whereas composites, whereas when ionomer is blended.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.264-265
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• 2008

While the reliability of bulk insulation has become important particularly in multilayer boards and embedded boards, electronics are to be used under various environments such as at high temperature and in high humidity. We observed internal space charge behavior for two types of epoxy composites under dc electric fields to investigate the influence of water at high temperature. In the case of glass/epoxy specimen, homocharge is observed at water-treated specimen, and spatial oscillations become clearer in the water-treated specimens. Electric field in the vicinity of the electrodes shows the injection of homocharge. In aramid/epoxy specimens, heterocharge is observed at water-treated specimens, i.e. negative charge accumulates near the anode, while positive charge accumulates near the cathode. Electric field is enhanced just before each electrode. In order to further examine the mechanism of space charge formation, we have developed a new system that allows in situ space charge observation during ion migration tests at high temperature and high humidity. Using this in situ system.