• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.408-411
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• 2009

The plastic working process is a well-known molding method to produce products with good mechanical properties whilst reducing material loss and production time at the same time. Among those methods, the nosing process is commonly used for valves, tubes and ammunition which require high mechanical properties since it provides change in shape without additional mechanical process, minimum material loss during the post-process and superior properties. However, high manufacturing cost and time are required for the large-size tubes due to the multi-step nosing processes. In addition, there are some potential risks due to the buckling and property variation caused by the nosing process, too. Therefore, the shell nosing process is investigated and used in this study in order to resolve the problems described previously. Thus, we could obtain the process with lower cost and improved efficiency by means of the shell nosing process.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1173-1176
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• 2004

In a previous work we reported the bistable property by doping a chiral material in a splay cell. The bistable states are the splay state and the metastable 180$^{\circ}$twist state. The retention time of the metastable state can be changed by the variation of d/p (cell gap over pitch), cell gap, pretilt angle, azimuthal anchoring force, liquid crystal material, and so on. In this paper we will present uniform bend transition and twist retention time improvement in a multi-domain BCSN LC cell by using the multi cell gap method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.744-746
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• 2003

A ZnO varistor with reference voltage 250V/mm was fabricated through the control of particle size in slurry and the variation of sintering conditions. It was found that to measure the flatness of the V-I characteristic curve in the small-current region and the flatness of the V-I characteristic curve in a large-current region was improved nonlinearity of the fabricated ZnO varistor. According to the IEC 60099-4 was measured the accelerated aging test and high current test of the distribution class surge varistor which is excellent in respect to the property of ZnO varistor.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1306-1308
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• 1998

Diamond like carbon(DLC) thin films possesed not only marvelous material charateristics such as large thermal conductivity, high hardness and being chemically inert, but also possesed negative electron affinity(NEA) properties. The NEA is an extremely desirable property of the material used in microelestronics and vacuum microelestronics device. DLC films were fabricated by pulsed laser deposition(PLD). The effect of the laser energy density and the substrate temperature on the properies of DLC films was investigated. The experiment was accomplished at temperatures in the range of room temperature to $400^{\circ}C$. The laser energy density was in the range of $6 J/cm^2$ to $16 J/cm^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.267-267
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• 2010

The structural and electrical properties of microcrystalline silicon films were investigated by hot wire chemical vapor deposition(HWCVD) often called catalytic chemical vapor deposition(Cat-CVD). The Si microcrystalline phase is easily controlled by changing the rate of the silane concentration of $SiH_4$ to $H_2$ during deposition. The Structural property was observed by Raman and SEM. Photo-conductivity and dark conductivity, and photo-sensitivity were observed by Sunsimulator (AM 1.5 illumination). The film color was changed by the variation of silane concentration. HWCVD is useful for the formation of Si thin films for solar cell and needs further commercialized development for mass production.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.805-810
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• 2000

The purpose of this study is to predict long-term structural safety on the Yonggwang Unit 3 prestressed concrete containment building. The aging-related degradations of its main structural materials are investigated and the effects of the property variation of time-dependent materials on the structural behavior of containment building are also assessed through the analysis on the ultimate pressure capacity. The nonlinear finite element analyses for both the design criteria condition a the present aging condition are conducted to assess the present structural capacity of the containment building As a result, it is verified that the structural capacity of the Yonggwang Unit 3 containment building under the present aging condition is judged to be still rugged. n addition, the sensitivity of the ultimate pressrue capacity of containment building according to th degradation levels of the structural materials are assessed. Finally, it is showed that the sensitivity levels are in the order of the tendon, rebar and concrete in case of individual material degradations, and the tendon-rebar, tendon-concrete and rebar-concrete in case of coupled material degradations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.137-143
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• 2008

High voltage MLCCs with C0G temperature coefficient characteristics could apply DC-DC invertor were investigated for its dielectric properties. Also we manufactured MLCC through various process and studied the characteristics of dielectric break down voltage [BDV] and dielectric property as the variation of thickness in the green sheet and how to pattern the internal electrode. As the thickness of green sheet is increase, the dielectric BDV per unit thickness is decreased. But as the pattern of internal electrodes were floated we could manufacture the high voltage MLCC maintained its dielectric BDV a unit.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.94-102
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• 1999

Ni/CGO cermets were fabricated as the anode for SOFC which uses CGO as the electrolyte. And their electrical conductivity, electrochemical reactivity, and thermal expansion coefficient were optimized through the variation of NiO/CGO particle size ration and their composition. The electrical conductivity of the cermet was increased abruptly at a certain Ni content and the percolation concentration was decreased with the decreasing particle size ratio. Anodic overpotential was also decreased with the decreasing particle size ratio. For a fixed ratio it showed a minimum value at 50 wt.%. Thermal expansion coefficient was increased monotonically with increasing Ni contents, however it did not depend on the size ratio. With three properties taken into account, the cermet of particle size ration of 0.03 and composition of 50 wt.% was judged to be optimal as the anode.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.344-348
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• 1999

Diamond like carbon(DLC) thin films possesed not only marvelous material characteristics such as large thermal conductivity, high hardness and being chemically inert, but also possesed negative electron affinity (NEA) properties. The NEA is an extremely desirable property of the material used in microelestronics and vacuum microelestronics device. DLC films were fabricated by pulsed laser deposition(PLD). Theeffect of the laser energy density and the substrate temperature on the properies of DLC films was investigated. The experiment was accomplished at temperatures in the range of room temperature to $600^{\circ}C$. The laser energy density was in the range of 6 $J/cm^2$ to 16 $J/cm^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.45-49
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• 2002

In this paper, we have studied about electromagnetic wave absorbing properties of ferrite-rubber composite with a variation of ferrite. Amounts of ferrite in a composite absorber were changed from 52 wt.% to 62 wt.%. As a result, it has been shown that the electromagnetic wave absorbing properties of ferrite-rubber composite are related to the amount of ferrite in composite absorber. As a summary, it could be controled the electromagnetic wave absorbing property of ferrite-rubber composite by changing some kinds of annex A and amount of ferrite.