• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.31-35
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• 2006

Degradation characteristics of filament-winded composites due to accelerated environmental aging have been evaluated under high temperature, water immersion and thermal impact conditions. Two kinds of laminated composites coated by an urethane resin have been used: carbon-fiber reinforced epoxy(T700/Epon-826, CFRP) and glass-fiber reinforced phenolic (E-glass/phenolic, GFRP). For tensile strength of $0^{\circ}$ composites, CFRP did high reduction by 25% under the influence of high temperature and water while CFRP showed little degradation. However for water-immersed $90^{\circ}$ composites both CFRP and GFRP showed high reduction in tensile strength. Bending strength and modulus of $90^{\circ}$ composites were largely reduced in water-immersion as well as high temperature environment. Urethane coating on the composite surface improved the bending properties by 20%, however hardly showed such improvement for water-immersed $90^{\circ}$ composites.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1262-1265
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• 2005

The picture quality of a plasma display panel is very sensitive to the phosphor characteristics such as decay time, surface state, and even longevity of phosphor material in itself. In this work, material characteristics of $Zn_2SiO_4:Mn$, $Y_2O_3-coated$ $Zn_2SiO_4:Mn$, and $YBO_3:Tb$, which are dominant in commercial application, were examined for investigating the aging characteristics of green PDP phosphors. It was found that $Y_2O_3-coated$ $Zn_2SiO_4:Mn$ are easily degraded at high temperature. However, all the samples were very weak after vacuum annealing. The luminescence intensity was decreased by order of one magnitude.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1276-1278
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• 1998

In this paper, aging characteristics of silicone rubber used for outdoor insulation have been investigated with regards to sunlight effect. For this purpose, silicone rubbers were aged under the artificial sunlight by use of xenon arc lamp(1500W) and various tests were performed such as tracking, breakdown, contact angle, stress, strain. And then, in order to elucidate the changes of material, analysis have been followed as follows; FT-IR, SEM and EDS. Regarding the effect of the sunlight, it was obs that the surface of test samples are severely da with decreased hydrophobicity, tracking resistan breakdown strength.

• Electrical & Electronic Materials
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• v.7 no.1
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• pp.7-14
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• 1994

Structural and optical characteristics in $SnO_2$/a-Se/Al sample by aging variation and applying constant voltage had been investigated. a-Se was varied with monoclinic structure and its surface was greatly exchanged. Its capacitance was first decreased and then increased and its photo-current, photo-voltage and photo-capacitance were increased gradually with day and applying voltage. From the results, crystallization of a-Se and dopant trap level formation had been identified. Also, it was acknowledged $SnO_2$/a-Se/Al sample is useful in photovoltaic and solid thin film cell.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.3
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• pp.21-30
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• 1991

Microstructural analysis was conducted to observe the effect of aging treatments in a Cr-Mn austenitic stainless steel containing nitrogen, and the amount, size, shape and distribution of precipitates were investigated. It was found that on water quenching from $1000^{\circ}C$ after holding 3 h at that temperature, the steel contained no precipitates observable by optical microscopy. Precipitation of phases begins at places most favorable for the formation of nuclei-in the boundaries of grains and twins. Precipitates were studied in detail by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Chemical compositions of precipitates were examined by the use of scanning transmission electron microscopy (STEM) together with an energy dispersive X-ray (EDX) microanalysis. Also chromium depletion adjacent to grain boundary precipitates was investigated by the use of Auger electron spectroscopy (AES) for a direct examination of the fracture surface chemistry.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2314-2316
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• 1999

This study describes the results of aging characteristics of polymer insulators through the tracking wheel test. In order to evaluate the reliability of polymer insulators, 4 polymer insulators which used in the field were selected. Electrical tests such as power frequency voltage test, steep-front impulse voltage test were performed after tracking wheel test. Chemical structure and contact angle were measured for investigating an aging characteristics. Although some changes have occurred on the surface of insulator, there are no critical changes between new and tracking wheel tested insulator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.76-78
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• 2001

In this paper insulation cover that being used in distribution line have been evaluated for aging characteristics. For evaluating its aging properties, we dismounted a variety of samples, like insulation covers for termination of deadend clamp, bushing, LA, COS and sleeve, in the fields. we performed mechanical properties test, electrical test, weathering test, etc. of these samples. And these samples are compared with virgin sample. Test results shows the bad mechanical strength in some part of samples. Especially, Insulation covers for the bushing terminations have cracks in the surface of samples.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.117-120
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• 2003

Fractal mathematics is being highlighted as a research method for classification of image. But the application of Fractal dimension(FD) has been required the complicated calculation method because of its complex repetition progressing. In this paper, it has been developed the new approach method to express the Fractal Dimension(FD) for aging level calculation and estimation system of outside insulator using special image processing algorithm. As a result after FD testing, the recognized aging estimation of FD has a very characteristics compared to the conventional visual inspection.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1393-1395
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• 1997

In order to investigate the interfacial effects on the aging of power cables, we analyzed recently failed cables using characterization techniques. In this study, some cables showed a convolution which can cause the concentration of electric field and carbonized impurities at the surface of insulation. Also there is a relation between the degree of cross- linking and volume resistivity. From the hot oil test, the sites of water tree and void coincided with each other.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.28-30
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• 2009

PDP panels with MgO protective layer are manufactured by using the "all-in-vacuum" process we have established [1]. This is the process aiming to keep the MgO surface as clean as possible after the evaporation. The panels are evaluated in term of discharge voltage, aging time, luminance, luminous efficacy, discharge time-lag. It is confirmed that the "all-in-vacuum" process particularly improves the aging time, discharge voltage and the discharge time-lag.