• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.65.1-65
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• 2000

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.04a
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• pp.28-29
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• 2000

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2002.11a
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• pp.48-49
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• 2002

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2002.04b
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• pp.47-47
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• 2002

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.11a
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• pp.24-26
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• 1997

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2004.11a
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• pp.177-181
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• 2004

• Journal of the Korean Electrochemical Society
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• v.11 no.4
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• pp.262-267
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• 2008

Effective dispersion of noble metal Pt-Ru catalysts was conducted for the application of direct formic acid fuel cell(DFAFC) electrodes by electrospray method. The amount of catalysts deposited on the electrodes increased with increasing deposition time. However, the performance of cell test decreased with the deposition time after 80 min. because of agglomeration of catalysts. With the conventional hand-spray method, the density of the anode catalysts deposited was $3.0\;mg/cm^2$ and the maximum power density of the MEA was $74\;mW/cm^2$. On the other hand, the MEA prepared by the electrospray method, showed a similar power density of $72\;mW/cm^2$. However, the density of the anode catalysts deposited was much lower than the case of the hand-spray and the density the anode catalysts in this case was $1.85\;mg/cm^2$.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.10
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• pp.933-940
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• 2009

To evaluate characteristics in spray flame, laminar counterflow is investigated on the effects of equivalence ratio and fuel by a two-dimensional DNS (direct numerical simulation). For the gaseous phase, Eulerian mass, momentum, energy, and species conservation equations are solved. For the disperse phase, all individual droplets are calculated by the Lagrangian method without the parcel model. n-Decane ($C_{10}H_{22}$) and n-heptane ($C_7H_{16}$) is used as a liquid spray fuel, and a one-step global reaction is employed for the combustion reaction model. As equivalence ratio increases, the fuel ignites early and the high temperature region spreads wider. The peak value of temperature, however, tends to once increase and then decreases with increasing equivalence ratio. The decrease in the peak value of temperature for the higher equivalence ratio condition is caused by the cooling effect associated with droplet group combustion. Since the evaporation of n-heptane is early, the high temperature region spreads wider than ndecane, but the peak values of temperature for both n-heptane and n-decane is almost same.

• Food Science and Preservation
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• v.22 no.5
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• pp.683-689
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• 2015

Response surface methodology (RSM) is a statistical procedure frequently used for optimization studies. The purpose of this study was to determine the optimal spray drying condition for manufacturing Sikhye powder using RSM. Independent variables included the additive contents of maltodextrin (MD), inlet temperature, and velocity of sample feed velocity. The dependent variables were water uptake (g), solubility (%) and particle size (${\mu}m$). Regression models describing the changes of water uptake (g), solubility (%) and particle size (${\mu}m$) with respect to the independent variables were statistically significant with coefficients of determination, $R^2$, greater than 0.9. The results indicated that the inlet temperature of the spray dryer was the most important independent variable that affected the water uptake (g), while the additive content of MD and the sample feed velocity had maximum effects on the solubility (%) and particle size (${\mu}m$) of the Sikhye powder, respectively. The optimum final product was expected to have the lowest possible water uptake (g) and particle size (${\mu}m$) but the highest possible solubility (%). In conclusion, the best spray drying conditions were as follows: additive MD content, 22%; inlet temperature, $140^{\circ}C$ ; and spray dryer sample feed velocity, 51 mL/min.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06b
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• pp.185-217
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• 1996

Pb(Mg1/3Nb2/3)O3은 높은 유전율과 전기저항 및 유전율의 온도변화율이 적은 Pb계 relaxor의 대표적인 재료로서 적층 세라믹 콘덴서 재료에의 응용이 크게 기대되고 있다. 그러나 산화물 분말을 이용하는 일반적인 세라믹스 합성방법으로는 Pb(Mg1/3Nb2/3)O3의 단일상의 합성이 어렵고, 합성과정에서 저유전율상인 pyrochlore상이 합성이 어렵고, 합성과정에서 저유전율상인 pyrochlore상이 공존하여 Pb(Mg1/3Nb2/3)O3의 전기적 특성을 저하시킨다. 본연구에서는 용액을 이용하여 Pb(Mg1/3Nb2/3)O3의 단일상을 합성하고자 하였다. 출발물질로는 값싼 금속염인 Niobium Oxalate, magnesium Nitrate 및 Lead Nitrate를 선정하고 증류수에 용해하여 혼합용액을 제좋고, 합성방법으로는 초음파 분무 열분해법과 에멀젼법을 이용하였다. 초음파 분무 열분해법에서는 75$0^{\circ}C$에서 합성한 분말을 다시 75$0^{\circ}C$에서 하소하여 Pb(Mg1/3Nb2/3)O3 단일상을 합성할 수 있었으며, 에멀젼법에서는 80$0^{\circ}C$에서 Pb(Mg1/3Nb2/3)O3 단일상을 합성할 수 있었다.