• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.814-817
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• 2004

Deterioration due to de-icer salt occurs in practice in concrete pavement, dike, barrier and similar structure. This paper reports the results of effect of de-icer salt on. durability of concrete structure in winter. To protect concrete structure from damage by de-icer salt in winter, the exposure test was performed using three countermeasures such as increase in design strength upto $350kg/cm^2$, application of ggbf slag powder, and concrete sealer. Of these, the method of increase in design strength upto $350kg/cm^2$ showed better durability for deterioration by de-icer salt.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1345-1348
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• 1997

$YBa_2Cu_3O_x$ samples were fabricated by MPMG(Melt Powder Melt Growth). The effects of the $Y_2BaCuO_5$ and Ag addition on $YBa_2Cu_3O_x$ were studied throuth the Jc, Tc and magnetization. For the application of the bulk HTSC to current limiter, fly wheel and current lead and so on, the critical charateristics were investigated and compared with the solid sintering method.

• Analytical Science and Technology
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• v.26 no.1
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• pp.27-33
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• 2013

Polyalkylsilanes such as poly(dialkyl)silanes and poly(monoalkyl)silanes were synthesized by sonochemical dechlorination-condensation method from (dialkyl or monoalkyl)chlorosilanes with sodium metal. Those polyalkylsilanes were analyzed for the properties such as thermal behaviors from TGA analysis and obtained ceramic yields of 10-20% for poly(dialkyl)silanes and 40-60% for poly(monoalkyl)silanes. Ceramic composite discs were prepared by the combined mixture of polyalkylsilanes and SiC powder and were tested by TGA and analyzed by SEM and XRD for the application as binder for ceramic composite precursors.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.431-435
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• 2012

Aluminum containing mesoporous molecular sieves Al-SBA-1 ($n_{Si}/n_{Al}$= 2, 5, 10, 15) was synthesized with a one-step method, and the catalyst was characterized with powder X-ray diffraction (XRD), nitrogen adsorption-desorption, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Finally, we studied the catalytic activities of Al-SBA-1 molecular sieves in Pechmann reaction of 3-methoxyphenol and Ethyl acetoacetate to get 7-methoxy-4-methyl coumarin. Four parameters reaction temperature, time, catalyst weight and reactants ratio were optimized.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.523-526
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• 2005

In order to traffic safety during winter season, snowfall and cold area has been spread the deicing chemicals, and the spraying amount is increasing every year. Use of deicing chemicals has been and will continue to be a major part of highway snow and ice control methods. Chloride-containing chemicals such as calcium chloride or rock salt are main deicers for the road. Extensive use of chloride deicers is, however, the source of substantial cost penalties due to their corrosive action and acceleration to deterioration concrete structures. Deterioration due to de-icer salt occurs in practice in concrete pavement, dike, barrier and similar structure. This paper reports the results of effect of de-icer salt on durability of concrete structure in winter. To protect concrete structure from damage by de-icer salt in winter, the exposure test was performed using three methods such as increase in design strength upto 32MPa application of granulated blast furnace slag powder, and concrete sealer. Of these, the method of increase in design strength upto 32MPa showed better durability for deterioration by de-icer salt.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1489-1491
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• 1996

The effect of Ag alloy sheath have been investigated in terns of critical current density and mechanical property. Nevertheless the continuous improvement of critical current density($J_c$) of Ag sheathed Bi2223 oxide superconducting wire processed with powder in tube(PIT) method, poor mechanical strength is still considered to be demerits for power application. In this study, we prepared two kinds of Ag- x wt% Cu alloy and pure Ag sheathed Bi2223 superconducting tapes. The hardness and tensile strength of prepared tapes has been measured. Their mechanical propertes were improved by Ag alloying.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.497-501
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• 2003

In order to manufacture ceramic capacitors for the industrial electronic parts application using Tape casting method, the dielectric properties as a functions of sintering temperatures and the fabrication conditions of green sheet were investigated to consider the possibility of applications. When the mixing ratio of powder and solvent in slurry was 65:35, the uniform and dense green sheets was obtained. The dielectric constant was increased as the sintering temperature Over 94% of relative density and high were obtained to the specimens sintered at $1000^{\circ}C$. We can find that the device sintered at higher temperature than $1000^{\circ}C$ showed the relative density over 94% and the dielectric constant over 2000.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.745-752
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• 1996

Wear property of plasma spray coating in $Cr_2O_3$ powder manufatured of spray dry method on the aluminum substrate was inspected for the application of piston-ring of automotive enginel. The plama spray coatings were varied with feed rate and particle size. Used the ball-on disc type tribometer, wear volume, friction, surface rougness were investigated. The delamination of the coating layer were observed with SEM. Also the cross-section of wear track were investigated, using optical microscopy. As a result of experiment, wear mechanism was addressed in the various coating process.

• Journal of the Korean institute of surface engineering
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• v.30 no.1
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• pp.57-62
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• 1997

Green-emitting $ZnGa_2O_4$ : Mn phosphors were synthesized by a thermal method and their low-voltage cathodoluminescent characteristics were examined for the field emitter display (FED) application. Low efficiency of $ZnGa_2O_4$ : Mn phosphors could be ascribed to the low penetration depth of into phosphors, which might results in charge accumulation on the phosphors screen. For increasing cathodoluminescent of $ZnGa_2O_4$ : Mn under low voltage excitation, wide band-gap oxide materials were added to the $ZnGa_2O_4$: Mn powder. It is found that the luminance can be increased by 20%. Measurement of leakage current on the phosphor screen shows that the enhancement of low-voltage cathodoluminescent by additive materials is mainly due to the consumption of surface charges on the phosphor.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.5 s.98
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• pp.98-103
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• 1999

The application field of porous mold is more and more expended. A mixture of alumina and cast iron is used for making porous mold using slip and vacuum casting method in this study. Slip casting is a process that slurry is poured into silicon rubber mold, dried in vacuum oven, debinded and sintered in furnace, In this procedure, slurry is composed of powder, binder, dispersion agent, and water. Vacuum casting is a technique for removing air bubbles existed in the slurry under vacuum condition. Since ceramics has a tendency of over-shrinkage after sintering, cast iron is used to compensate dimensional change. The results shows that sintering temperature has a great effect on characteristics of alumina-cast iron composite sintered parts. Finally ceramic-metal composite sintered mold can be used for aluminum alloy casting of shoe mold using this process.