• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.346-347
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• 2012

최근 화석연료 대체 에너지원으로서 자동차용으로 연구 개발 및 응용되고 있는 고분자 전해질 연료전지(PEMFC: Proton exchange membrane fuel cells)에서 분리판(Bipolar Plate)은 스택 전체 무게의 80%, 스택 가격의 60% 정도로 가장 높은 비중을 차지한다. 분리판은 연료와 산화제를 공급해주는 통로 및 전지 운전 중에 생성된 물을 제거하는 통로 역할과 anode, cathode로서 전극 역할을 통해 스택 전력을 형성하는 핵심 기능과 전지와 전지 사이의 지지대 역할을 한다. 따라서 분리판은 전기전도성, 내부식성 및 기계적 특성이 우수해야함은 물론이고, 얇고 가벼우며 가공성이 뛰어나야 한다. 현재 가장 많이 사용되고 있는 금속 분리판 소재 중 스테인리스 스틸은 전기적, 기계적 특성 및 내부식성이 우수한 반면, 가격이 비싸고, 중량이 무거운 단점이 있다. 따라서 본 연구에서는 DC 반응성 마그네트론 스퍼터링법으로 전기적, 기계적 특성 및 내부 식성이 우수한 TiN, TiCN 박막을 스테인리스에 비해 중량이 1/3, 소재 단가가 1/4인 알루미늄 기판 위에 증착하여 박막 물성을 평가하였다. DC Power는 400 W, 기판과 타겟 사이의 거리는100 mm, 공정 압력은 0.5 Pa로 고정하였고, 3 inch의 지름과 순도 99.95%를 갖는 티타늄 타겟을 사용하였다. 공정 가스는 Ar을 주입하였으며, 질소와 탄소의 공급원으로는 질소($N_2$)와 메탄($CH_4$) 가스를 사용하여 챔버 내 주입혼합가스의 전체 유량을 50 sccm으로 고정시켰다. 증착된 박막의 전기적, 기계적 특성을 측정하였고, X-ray diffraction (XRD), Scanning electron microscope (SEM)을 이용하여 박막의 미세구조 및 표면 상태를 확인하였다. 또한, 내부식 특성을 평가하기 위해 potentiostatic, potentiodynamic 법을 이용하여 박막의 부식저항을 측정하였다. 증착된 TiN 박막의 경우 질소 함량의 증가에 따라 박막 증착속도는 감소하는 경향을 보였다. 이는 타겟 부근의 질소 라디칼 비율이 증가함에 따라 질화반응이 촉진된 것으로 생각된다. 또한, 증착된 TiN과 TiCN 박막은 반응성 질소 유량과 탄소 유량에 따라 각각 다른 미세구조를 가지는 것을 확인하였다. TiN과 TiCN은 NaCl형의 면심입방격자(FCC)로 같은 구조이며, 격자상수가 비슷하여 전율고용되어 TiCN을 형성하고, 탄소와 질소의 비에 따라 전기적 기계적 특성이 달라짐을 확인하였다.

• Elastomers and Composites
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• v.43 no.4
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• pp.230-240
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• 2008

In order to synthesize polymer particle containing inorganic material, styrene and nbutylmetacrylate were copolymerized with alumina by dispersion polymerization. The ratio in weight of styrene to n-butyl methacrylate was 3:1. Poly(N-vinyl pyrrolidon) and 2,2'-azobis(isobutyronitrile) were added as stabilizer and as initiator, respectively. The change of particle size was investigated with concentration of initiator, the type of medium, the mixed solubility parameter (${\delta}_{mix}$) of medium, and coupling agent. The enhancement in concentration of initiator resulted in slight increase of particle size. The increase of polarizability in medium also yielded the increase of particle size. In case of changing the ratio of isopropanol to distilled water, we could find relationship of $[{\delta}_{mix}]^{-4.01}\;{\propto}$ particle size and $[{\delta}_{mix}]^{-0.83}\;{\propto}$ particle size distribution(PSD). The type and the concentration of coupling agent showed no effect on the particle size and PSD.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1465-1471
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• 2013

The electrical and mechanical properties of room temperature vulcanized (RTV) silicone rubber composites are investigated as functions of multi-walled carbon nanotube (CNT), carbon black (CB), and thinner content. The thinner is used to improve the CNT and CB dispersion in the matrix. The electrical and mechanical properties of the composite with CNT are improved when compared to the composite with CB at the same content. As the thinner content is 80 phr, the electric resistance of the composite decreases significantly with the CNT content and shows contact point saturation of CNT at 2.5 phr. As the thinner content increases, the dispersion of conductive particles improves; however, the critical CB content increases because of the reduction in the CB weight ratio. It is believed that an electrode that needs good flexibility and excellent electrical properties can be manufactured when the amount of CNT and CB are increased with the thinner content.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.4
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• pp.437-444
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• 2008

Anti-obesity effects of ginseng and herbal plant mixtures were investigated to develop natural materials for anti-obesity. After inducing obesity with high fat diet for 8 weeks in male SD rats, ginseng and herbal plant mixtures DM1 (ginseng, puer tea, opuntia) and DM2 (ginseng, puer tea) were administrated orally to rats for another 8 weeks. During administration, food efficacy ratio and body weight of rat were measured twice weekly. After administration, body weight, body fat contents, and serum lipid level were estimated for anti-obesity effect and hematological analysis blood level of ALP and ASP was checked for safety. Body weight in rats fed high fat diet was significantly increased. Body weight in obese rats induced by high fat diet was significantly decreased by DM1 and DM2 feedings. The amount of body fat (epididymal, perirenal and visceral fat, brown adipose tissue) was significantly reduced by DM1 and DM2 treatments. The amount of TG, the concentration of leptin in blood plasma, and the concentration of insulin in blood plasma were significantly diminished by DM1 and DM2. Lipid accumulation on liver was reduced in DM2. There were no side effects among all groups according to blood analysis, hematological findings, and body weight. The findings of this study suggest that DM1 and DM2 may be effective materials for anti-obesity through reducing plasma triglyceride and body fats, and also decreasing body weight without side effects.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.6
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• pp.868-876
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• 2014

This study was performed to investigate the effects of lactic-fermented rice flour on the quality characteristics of pan-fried food (Jeon). Pan-frying flour containing 5~20% lactic fermentation rice flour mixture was prepared. In rapid visco analyzer examination, peak viscosity, trough, final viscosity, breakdown, and setback of the lactic-fermented rice flour mixture were lower than those of rice flour or wheat flour. The L-value (lightness) of Jeon decreased with increasing the ratio of lactic-fermented rice flour. On the other hand, a-value (redness) and b-value (yellowness) increased with increasing ratio of lactic-fermented rice flour. Texture profiles showed that Jeon prepared with lactic-fermented rice flour mixture had higher springiness and gumminess than 100% rice flour. The oil absorptions of Jeon prepared with 100% rice flour and 20% lactic-fermented rice flour were 7.5% and 6.33%, respectively. For digestive properties, Jeon prepared with lactic-fermented rice mixture showed a greater amount of rapidly digestible starch and lower amount of slowly digestible starch. In the sensory evaluation, Jeon prepared with lactic-fermented rice mixture showed higher scores for appearance, flavor, and taste than others (rice flour and wheat flour). Especially, Jeon prepared with 10% lactic-fermented rice mixture showed the highest overall preference. In conclusion, the results demonstrate that lactic-fermented rice flour may prove quite useful as a pan-frying flour with desirable qualities properties.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.1
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• pp.21-27
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• 2018

Synthesis of ferromagnetic composite materials for the $Cu-BaFe_{12}O_{19}$ system by mechanical alloying (MA) has been investigated at room temperature. A mixture of copper and barium ferrite with a weight ratio of $Cu:BaFe_{12}O_{19}=4:1$, 3 : 2, 2 : 3 and 1 : 4 was used. It is found that $Cu-BaFe_{12}O_{19}$ composite powders in which $BaFe_{12}O_{19}$ is dispersed in copper matrix are successfully produced by mechanical alloying of $BaFe_{12}O_{19}$ with Cu for 80 min. in all composition. The change in X-ray diffraction patterns and magnetic properties reflects the details for the formation of ferromagnetic metal matrix composite of pure Cu and $BaFe_{12}O_{19}$ during mechanical alloying. Magnetization of $Cu-BaFe_{12}O_{19}$ composite powders gradually increases with increasing the amounts of barium ferrite, whereas coercive force of MA powders gradually decreases due to the refinement of barium ferrite powders with ball milling. However, it can be seen that the coercivity of $Cu-BaFe_{12}O_{19}$ MA composite powders with a weight ratio of $Cu:BaFe_{12}O_{19}=4:1$ and 3 : 2 ball-milled for 80 min. is still high value of 1400 Oe and 1450 Oe, respectively suggesting that the refinement of barium ferrite powders during ball milling process tend to be suppressed due to the ductile copper.

• Food Science and Preservation
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• v.19 no.2
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• pp.223-228
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• 2012

The effects of soybean powder and $chungkukjang$ powder on the quality characteristics of bread were investigated. The nutritional elements of the soybean powder, $chungkukjang$ powder and wheat flour differed remarkably. The average crude protein, ash, crude lipid, and fiber of soybean powder and $chungkukjang$ powder were approximately 3, 15, 8 and 5 times higher than those of the wheat flour, respectively. The properties of the dough to which soybean powder and $chungkukjang$ powder were added, i.e., its water absorption (%), development time (min) and stability (min) were measured with a farinograph. The water absorption, and development time of the farinogram increased, but its stability decreased when soybean powder and $chungkukjang$ powder were added to white wheat flour. As long as the mixture rate of soybean powder and $chungkukjang$ powder increased, the loaf volume of the bread declined, but the weight significantly increased. The L value decreased, but the a and b values increased in bread crumb that was made from soybean powder and $chungkukjang$ powder. The white wheat flour to which 10% soybean powder and 5% $chungkukjang$ powder were added had the highest scores in flavor, color, texture, taste, and overall acceptability in the sensory evaluation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.4
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• pp.470-475
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• 1999

This study was conducted to evaluate the utilization of animal by-product mixture (ABPM) as a dietary animal protein source of fish meal replacer, and to determine the effect of dietary chromic oxide in growing rainbow trout, Oncorhynchus mykiss. ABPM is a mixture of five anmial by-products such as meat and bone meal (MBM) feather meal (FM), squid live, powder(SLP), poultry by-product (PBP) and blood- meal (BM) at a specific weight based ratio. Diet 1 and 2 were formulated on a isonitrogenous and a isocaloric basis of $46.5\%$ crude protein and 16.7 KJ/g diet; diet 1 (WFM 100), $100\%$ of the animal protein source came from white fish meal; diet 2 (ABPM 40), $60\%$ WFM+$40\%$ ABPM as the animal protein source; diet 3 (-Cr) commercial diet without chromic oxide; diet 4 (+Cr), commercial diet with chromic oxide. After eight weeks of feeding trials, fish fed diet 2 had a significantly lower body weight gain (WG) and feed efficiency (FE) than that of fish fed the other diets (P<0.05). When comparing diet 3 with diet 4, no significant differences were found in WG and FE (P>0.05). There were no significant differences on condition factor, hematocrit level, serum phosphorus, bone phosphorus, whole body phosphorus, and bone ash among fish from all four diet groups. Fish fed diet 4 had a significantly higher whole body lipid than that of fish fed the other diets (P<0.05), These results indicated that ABPM could be used less than $40\%$ in growing rainbow trout with a sufficient period of acclimation, In addition, the $0.5\%$ of chromic oxide can be used to determine the apparent digestibility of the nutrients in the feed without any adverse effects on growth and body composition.

• Journal of Nutrition and Health
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• v.36 no.4
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• pp.352-358
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• 2003

This study was performed to investigate the effects of liquid culture of Agaricus blazei on the lipid metabolism and enzyme activities in growing male rats. Sprague-Dawley rats were given four different types of diets for a succeeding period of 5 weeks, respectively: a normal diet group (7% corn oil), a high fat diet group (7% com oil + 15% lard), a 20 or 30% Agaricus diet groups (high fat diet + 20 or 30% Agaricus in water) according to the levels of Agaricus supplementation. The body weight gains, food intake, food efficiency ratios, and hepatic, kidney, spleen and pancreas weights of the rats fed 20 or 30% Agaricus diets were similar to those of the rats fed high fat diet. The epididymal fat pad weight of the rats fed high fat diet and 20 or 30% Agaricus diets were significantly higher than that of the rats fed normal diet. The concentrations of serum triglyceride, total cholesterol, LDL-cholesterol and HDL-cholesterol, and the activity of glutamic pyruvic transaminase in the rats fed 30% Agaricus diet were significantly lower than those in the rats 114 high fat diet. But the concentrations of hepatic total cholesterol and triglyceride of rats fed the 20 or 30% Agaricus diets were similar to those of rats fed the high fat diet. The HDL-oholesterol/total-cholesterol ratio of the rat fed 30% Agaricus diet was significantly higher than that of the rats fed high fat diet, The activity of glutamic oxaloacetic transaminase in the rats fed 20 or 30% Agaricus diets were similar to those in the rats fed high fat diet. There were no differences in the concentrations of total protein, hemoglobin and glucose, and the activities of alkaline phosphatase, and the atherogenic index in the serum among the experimental groups. These results showed that the 30% Agaricus diet feeding decreased the total cholesterol, the triglyceride and the LDL-cholesterol, and increased the HDL-oholesterol/total cholesterol ratio in serum of rats.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.7
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• pp.908-914
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• 2007

Sasa borealis (bamboo) is a perennial medicinal plant and its leaves are utilized widely in Korea. In this study, effects of bamboo leaves (Sasa borealis) extract on the physical, textural, and sensory characteristics of cooked rice were examined. Four kinds of cooked rice were prepared with 0.0% (control), 0.2%, 0.3% or 0.4% of the extract (w/w). Moisture content of the cooked rice decreased with increasing amounts of extract. Color of the cooked rice was darkened gradually with increasing amounts of extract and appeared yellowish-brown. Among the four textural properties, only hardness increased significantly by the addition of the extract. Sensory evaluation was significantly different in terms of unique rice flavor, bamboo flavor, color, unique rice taste, bamboo taste, viscosity, hardness, adhesiveness, and coarseness among the control group and the group with 0.2%, 0.3%, and 0.4% of the extract; however, overall acceptancy was not significantly different among the four groups. In conclusion, concerning overall sensory evaluation, cooked rice with 0.2% bamboo leaves (Sasa borealis) extract showed the best result.