• 한국전기전자재료학회논문지
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• 제26권7호
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• pp.522-527
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• 2013

In this paper, We studied the change of surface and variation of elements on both electrodes of hydrogen generator of alkaline electrolysis in use of FE-SEM and SIMS. We used the stainless steel 316(600 ${\mu}m$) as electrode in condition of 25%KOH, $60^{\circ}C$ Temperature. The results show that the intensity of elements (C, Si, P, S, Ti, Cr, Mn, Fe, Ni, Mo) of Positive Electrode are decreased as much as about $10^1{\sim}10^3 $than the original electrode. Thickness of Positive Electrode is decreased about 40 ${\mu}m$ after chemical reaction. The negative electrode, however, shows a slight variation in the intensity of elements (C, Si, P, Fe, Ni, Mn, Mo) but Change of thickness and surface' shape of electrode show nothing after chemical reaction. The change in thickness and variation of Stainless Steel 316 cause the lifetime of electrode to be shorted. We also observed hydrogen, oxygen, potassium in both electrodes. Especially, The potassium is increased in proportional with depth of positive electrode. this means the concentration of alkali solutions is changed. and so we have to supply alkaline solution to generator in order to produce same quantity of hydrogen gas continuously. we hope that this study gives a foundation to develop the electrode for hydrogen generator of alkaline electrolysis.

• 한국축산시설환경학회지
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• 제11권1호
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• pp.61-70
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• 2005

본 실험은 남은 음식물에 유기성 부산물인 육계분, 제과부산물, 밀기울, 맥강 등을 주요 수분흡수제 또는 영양 보충제로 혼합한 후 rotary drum 방식을 이용하여 양돈 사료화 하는데 있어서 이상적인 배합비 도출을 위한 공정단계별 사료의 영양적 flow를 4차 시험에 걸쳐서 추적하였다. Rotary dm 방식을 이용한 살균 및 숙성 과정을 거치면서 영양소의 변화 폭은 매우 낮았으며, 살균 및 숙성 처리 후의 건물 손실율은 $8{\~}15\%$ 수준이었다. 시험별로 영양소 변화는 혼합되는 사료 원료의 종류에 따라 다르게 나타났다. 남은 음식물, 퇴적발효육계분, 제과부산물, 맥강의 최적 혼합 비율은 45: 10: 22.5:22.5 이었고, 이때 사료간의 뭉쳐지는 현상을 극복할 수 있었다. 결과적으로 rotary durm 방식으로 살균하고, 숙성한 남은 음식물 혼합물은 양돈 사료로서의 충분한 사료 영양적 가치가 있었다.

• 한국응용과학기술학회지
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• 제8권2호
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• pp.105-114
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• 1991

In relation to the preparation of Langmuir-Blodgett thin film, four kinds of N-alkylpyridiniurn bromide were synthesized. The values of surface tensions of these materials, measured with a Traube stalagmometer, gave the relationship between the critical micells hydrophobic radical and between CMC and temperature. Values of thermodynamic properties(${\Delta}H^0_m,\;{\Delta}S^0_m,\;{\Delta}G^0_m,$) for the formatoin of micelle were also obtained. Experiments gave the following results; at the temperature range between 40 and 60$^{\circ}C, CMC of Hexadecyl-, Octadecyl-, Eicosyl-, and Docosyl-Pyridinium Bromide were $7.64{\times}10^{-4}{\sim}9.13{\times}10^{-4},\;3.85{\times}10^{-4}{\sim}4.60{\times}10^{-4},\;2.00{\times}10^{-4}{\sim}2.39{\times}10^{-4},\;and\;1.07{\times}10^{-4}{\sim}1.28{\times}10^{-4}$ mol/l, respectively. Surface tension, ${\Gamma}_{CMC}$, of those were 33.49${\sim}$36.00, 34.78${\sim}$37.61, 35.49${\sim}$37.61 and 38.76${\sim}$55.80 dyne/cm, respectively, The relationship between CMC and the mumber of carbon atoms in the hydrophobic radical, N was expressed as follows : Log(CMC)=A-BN where A and B are constants. At the temperature range between 40 and 60$^{\circ}C$, the change of Gibbs evergy (${\Delta}G_m$) for one methylene group ($-CH_2-$) were -0.65RT, respectively, The minus values of enthalpy change (${\Delta}H_m$) suggest that the formation of micelle is exothermic. Additionally, the overall increase in the entropy change (${\Delta}S_m$) with respect to the temperature increase suggests that the formation of micelle is attained by a exothermic enthalpy directed process.

• Tribology and Lubricants
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• 제34권6호
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• pp.279-283
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• 2018

In this study, we investigate the behavior of abrasive particles and change of the stick-slip pattern according to chemical mechanical polishing (CMP) process parameters when a large number of abrasive particles are fixed on a pad. The CMP process is simulated using the finite element method. In the simulation, the abrasive grains are composed of those used in the actual CMP process. Considering the cohesion of the abrasive grains with the start of the CMP process, abrasive particles with various sizes are fixed onto the pad at different intervals so that stick-slip could occur. In this analysis, we determine that when the abrasive particle size is relatively large, the stick-slip period does not change as the pressure increases while the moving speed is constant. However, if the size of the abrasive grains is relatively small, the amount of deformation of the grains increases due to the elasticity of the pad. Therefore, the stick-slip pattern may not be observed. As the number of abrasive particles increases, the stick-slip period and displacement decrease. This is consistent with the decrease in the von Mises yield stress value on the surface of the wafer as the number of abrasive grains increases. We determine that when the number of the abrasive grains increases, the polishing rate, and characteristics are improved, and scratches are reduced. Moreover, we establish that the period of stick-slip increases and the change of the stick-slip size was not large when the abrasive particle size was relatively small.

• Korean Chemical Engineering Research
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• 제61권3호
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• pp.446-455
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• 2023

공기부양반응기(airlift reactor) 내의 액체순환속도(liquid circulation velocity)를 예측하기 위한 수학적 모형이 유체순환고리(fluid circulation loop)에 대한 기계적 에너지 수지를 기초로 개발되었다. 그 모형은 90° 방향전환으로 인한 에너지 손실과 반응기의 각 부위에서의 마찰로 인한 에너지 손실 그리고 단면적의 변화로 인한 에너지 손실을 모두 고려하였다. 마찰과 방향전환 그리고 단면적 변화에 의한 손실계수를 각각 고려한 모형이 집중매개변수(lumped parameter)를 사용한 기존의 모형보다 액체순환속도를 더 잘 예측할 수 있었다. 순환액체속도는 추적자펄스방법(tracer pulse method)으로 측정하였다. 개발된 모형은 상하부에 연결관(connecting pipe)을 갖는 외부순환 공기부양반응기에서 얻은 본 연구의 실험 결과의 대부분은 물론이고 다양한 형태의 공기부양반응기에서 얻어진 다른 연구자들의 결과도 ±20%이내의 오차로 잘 예측할 수 있었다. 외부 및 내부순환 공기부양반응기에서 순환유체의 90° 방향전환과 관련된 손실계수에 대한 유용한 실험식을 구하여 액체순환속도를 예측하는 데 사용하였다.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1887-1890
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• 2010

Cross-linked polystyrene supported aluminium triflate (Ps-Al(OTf)$_3$) was found to be an efficient and chemoselective heterogeneous Lewis acid catalyst for the direct conversion of arenes to sulfones using sulfonic acids as sulfonylating agents. The solid acid catalyst is stable (as a bench top catalyst) and can be easily recovered and reused without appreciable change in its efficiency.

• 대한화학회지
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• 제10권2호
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• pp.103-108
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• 1966

The effect of temperature on the critical micelle concentration of dodecylpyridinium chloride has been determined by electrical conductance method over the range from $5^{\circ}C\;to\;50^{\circ}C$. The values of the change in heat content, ${\Delta}H_m$, and the other thermodynamic parameters have been estimated using the equation of temperature dependence on the critical micelle concentration for the same temperature range. The significance of these thermodynamic quantities and their relations to the various current theories of micelle forming processes were discussed.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.243-245
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• 2003

The continuous fermentation process for exe-biopolymer production with Cordyceps militaris has been developed in this research. With the change of dilution rate, biopolymer production has been changed and the maximal biopolymer production has been achieved when the dilution rate was 0.0225/hr. The maximum mycelium concentration and biopolymer concentration were 8 g/L and 4.2 g/L, respectively.

• 대한화학회지
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• 제4권1호
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• pp.83-84
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• 1957

I have studied on the Enzymes of rice bran during preservation heating at various periods at constant temperatures and under atmospheric pressure. I found following facts through experiments. 1. It increases A. V. ratio of rice bran oil at above 120$^{\circ}C$., but it does not effect on its fat by heating. 2. It increases A. V. ratio of rice bran oil rapidly at below 90$^{\circ}C$., while it does not effect on its fat during preservation.

• Bulletin of the Korean Chemical Society
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• 제28권7호
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• pp.1156-1158
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• 2007

Valerophenone shows a dramatic shift of photoreactivity by a cyclopropyl group at alpha position to the carbonyl group. By the minor change of structure, the diastereoselectivity of the Yang photocyclization is reversed and the ratio of cyclization to elimination products increases significantly.