• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1170-1173
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• 2006

Active layer patterned OTFT was obtained on a plastic substrate using the optimal growth condition of pentancene thin films as active layer and parylene thin films as passivation layer. Tranditional photolithography was performed to use a dry etch to pattern the material stack. The pentacene thin film and parylene thin film were deposited onto a plastic substrate using PC-OVD and CVD, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.487-490
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• 2006

We propose a new method to achieve well-defined surface properties of the polymeric gate dielectrics without using SAM technique and inserting another organic/inorganic buffer layer. Pentacene thin film transistors(OTFTs) fabricated with the polyimide gate insulators with different side chain structures were demonstrated. Further, a relationship between the surface properties (surface morphology, surface energy, etc) of the films and the performance of OTFTs have investigated, which will be given in more detail in presentation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.6
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• pp.462-468
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• 1999

Room temperature vulcanizing (RTV) silicone rubber has been widely used to coat porcelain insulators to render water repellency to prevent formation of water film on the surface and thus to suppress the leakage current and consequently flashover. However, the electrical property and the hydrophobicity of RTV silicone rubber coating under outdoor condition may be influenced by many environmental factors. In this studyvarious treatments, such as salt-fog, salt water immerging and UV irradiation were applied to the samples to investigate the change of the electrical property and hydrophobicity. As a result the leakage current increased and contact angle decreased asthe degradation time is longer. But the degraded RTV silicone rubber has recovered its hydrophobicity during the drying time in ambient condition because LMW(Low Molecular Weight) silicone fluid diffused from the bulk to the surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.451-454
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• 2002

A silicone rubber has been used so many dielectric materials for extremely high voltage(EBW) electric appliances. The reason why it is very stable in the thermal, mechanical and electrical environment. In this paper, we have studied the dependence of dielectric characteristics of silicone rubber on frequency-dependent variation. The dielectric characteristics were measured in the temperature range of 25[$^{\circ}C$] and 150[$^{\circ}C$]. Also we measured in the voltage range of 1[V] and 20[V]. The energy of activation on the dielectric loss obtained 2.44[kcal/mol], 2.1[kcal/mol], 1.63[kcal/mol] and 1.57[kcal/mol] by appling respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.427-430
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• 2002

This paper presents on contamination performance of polymeric outdoor insulator with different contaminant accumulation. The ESDD (equivalent salt deposit density), tracking resistance and clean-fog test were performed to investigate the characteristics of contamination performance on polymeric outdoor insulator. Furthermore, we evaluated together with the porcelain samples for its comparison. It is found that ESDD of polymeric and porcelain insulator depends on the installation position. This surface accumulation of contaminant lead to the loss of surface hydrophobicity, expecially upper shed part of polymeric insulator. In addition, the effect of an artificial contaminant on the tracking resistance by inclined-plane method and leakage suppression ability under clean fog was surveyed. The time of tracking failure did not appear to change significantly with a much contaminant accumulation, while leakage current under clean-fog increased.

• Electrical & Electronic Materials
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• v.10 no.3
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• pp.247-254
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• 1997

Internal voids in insulators give rise to partial discharge, which causes a local breakdown and even entire insulation breakdown. Recently, the necessity of establishing the way to diagnose the aging of insulation materials and to predict of insulation breakdown become important. The purpose of our work are to investigate the treeing phenomena with an artificial needle shaped void by the charge of discharge and acoustic emission pulse in each phase angle area at the same time. We analyzed the .PHI.-QA-t pattern and .PHI.-AEA-t pattern using statistic operators such as pulse magnitude, pulse number, skewness, kurtosis. Therefore, the relation between the charge of discharge and acoustic emission pulse will be helpful to predict the breakdown just before the breakdown occur.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.348-350
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• 2002

In the high-power tests to be performed on electrical apparatus as switchgears, transformers, insulators, cable and so on the results of tests on these apparatus are extremely important to evaluate the performance of test object. The reliability of the results depends on the reliability of measuring systems used in the laboratories where tests are performed. This paper introduces factors of uncertainty and describes estimation of uncertainty in high-voltage measuring system used in high-power testing LAB. 1 in KERI.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1490-1492
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• 2001

Recently polymer composite materials has been replacing the porcelain in suspension insulators as a insulating material. The polymer composite materials are introduced into Korea from the abroad, so there is, actually, no formal standard of assessment Both the porcelain insulator specifications and composite material test specifications are being used at the same time. The aim of this project is to establish a systematic standard suitable to current situations considering the trends of its production within Korea. This would protect the inner-markets against the market-opening and would promote the industrial development within a country.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.431-434
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• 2002

This paper reports on the evaluation of weathering resistance, tracking test and salt-fog of various kinds of cycloaliphatic epoxy systems. It was found that UV irradiation induced the loss of hydrophobic level due to the chain scission attack at the surface. It could be seen that samples containing an UV absorbent/antioxidant and a silicone oil additive knave a good performance in weathering ageing, whereas ATH filled ones have high resistance against tracking failure than others. Under salt-fog test, specimens mixed with silicone oil could suppress leakage current development. It was thought that silicone oil mixed into cycloaliphatic epoxy system could lead to lower the surface energy and to retain hydrophobic properties for a long time, which are desirable for outdoor performances.

• The Korean Journal of Ceramics
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• v.5 no.4
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• pp.363-367
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• 1999

New glass ceramics were investigated for the application as substrates to be used in hard disk devices. The glass system to precipitate lithium di-silicate was studied so as to optimize the composition to realize very high surface flatness. The addition of small amount of several metal oxides with high valences had very drastic effects on the microstructure, because they played a role of crystallization agents, and consequently it determined surface flatness even after the polishing process. The possible mechanism changes of crystal growth due to the addition of metal oxides were discussed in relation to the final micro-texture development. The glass ceramics with very high surface flatness(Ra=7.1 $\AA$) was obtained by the addition of the mixture of $P-2O_5 \;and \;MoO_3$ as crystallization agents.