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이차전지내 발생하는 수소-산소 혼합기체 재결합용 촉매의 성능 측정 및 이론적 모델 연구
김용식,장민환,주재백,Kim, Yong-Sik,Chang, Min-Hwan,Ju, Jeh-Beck 한국전기화학회 2014 한국전기화학회지 Vol.17 No.1
이차전지에서 충전이나 방전시 발생하는 수소-산소 혼합기체의 재결합반응용 촉매들의 성능을 측정하고 모델식을 정립 및 해석하여 실험값과 비교하였다. 전기분해셀을 이용하여 수소-산소 혼합기체를 발생시켰으며 고정층 촉매 반응기를 사용하여 촉매의 성능을 측정하였다. 생성된 물의 양과 전기 분해셀에서 감소된 전해질 양의 비인 수율은 전해셀내 전해질인 KOH의 농도 및 인가전류의 크기가 커질수록 증가함을 보였으며 촉매 1의 성능이 가장 우수하였고 수율은 60%이하의 값을 보였다. 이론적인 패러데이 법칙을 이용하여 계산된 패러데이 수율은 촉매 1의 경우 거의 최대 100%에 가까운 수율도 보여주었다. 여러 촉매들은 유량속도에 따라 물의 생성량의 범위가 5-40 g/day인 성능을 보여주었다. 준균질 촉매 반응기 모델식으로 해석한 결과 반응기 내부의 가장 뜨거운 부분은 유량속도가 커질수록 출구 쪽으로 이동하고 온도는 $440-480^{\circ}K$ 사이였으며 점화온도에는 못 미치는 것으로 나타났다. 반응기 출구에서의 평균 수소농도로부터 계산한 물의 생성량을 실험값과 비교한 결과 유량속도가 약 $0.5cm^3/sec$이하인 경우 모델 결과와 부합됨을 알 수 있었으나 그 이상의 유량속도에서는 차이가 남을 알 수 있었다. The performance of catalysts for the recombination of oxyhydrogen gas was measured and compared with the results obtained from theoretical model. The oxyhydrogen gas was generated by the electrolysis cell and recombined through the fixed bed catalytic reactor. The yield that is the ratio of water-amount produced to the water-amount consumed in the electrolysis cell was increased with the increase of KOH concentration in electrolysis cell and the applied current. The catalyst 1 showed the best performance and the yield was under 60 %. The faradic yield calculated by Faraday's law showed about 100% in maximum with catalyst 1. The production rate of water generated by the recombination was 5-40 g/day dependent on the flow rate of mixed gas. Considering the results calculated from the pseudo-homogeneous catalytic reactor model, the hot point inside the reactor was moved to the direction of outlet and the maximum temperatures were $440-480^{\circ}K$ when the gas flow rate increased. The production rate of water calculated from the theoretical model showed good agreement with experimental results below the flow rate of $0.5cm^3/sec$, but there were much differences above that flow rate.
메추리의 6개 칼슘공급원에 따른 진정이용칼슘과 외견상이용칼슘가의 비교
김용식,선상수,명규호 ( Y . S . Kim,S . S . Sun,K . H . Myung ) 한국축산학회 1985 한국축산학회지 Vol.27 No.5
True available calcium(TAC) values of 6 calcium supplements were a little greater than apparent available calcium(AAC) value of them, however, no significant difference was found between two kinds of available calcium values. There were significant differences (p$lt;0.01) among each TAC and AAC values of 6 calcium supplements. TAC values of calcium carbonate and oyster shell in mixed diets were significantly (p$lt;0.05) greater then AAC values of them. TAC and AAC values of calcium carbonate were the highest as 99.94%±2.10 and 98.45%±1.07, and those of oyster shell were the lowest as 67.78%±1.96 and 67.40%±2.07 respectively.
광주, 전남지역에서의 업종별 악성종양 발생에 관한 연구 - 1종 의료보험 자료를 중심으로 -
김용식,오원문,박형철,최진수,송인현,Kim, Yong-Sik,Oh, Won-Moon,Park, Hyung-Cheol,Choi, Jin-Su,Song, In-Hyun 대한예방의학회 1990 Journal of Preventive Medicine and Public Health Vol.23 No.2
In order to investigate the occurrence characteristics of cancer in terms of industry in Kwangju-Chonnam area, medical utilization records of industrial medical insurance corporations during the period of 1987 to 1988 were reviewed for the identification of neoplastic disease. The cases obtained from the medical records were followed up for the verification and to get additional information. Standardized incidence data were compared by occupational characteristics. Multiple logistic regression analysis was applied to analyze the difference of incidence or distribution of cancer as a whole or of some selected cancer. Total cases of cancer identified were 242 during the study period. Annual incidence rate was calculated as 123.1 per 100,000 person. The frequent types of cancer were cancers of stomach, liver, lung, colon and rectum, bladder and lymphoma in descending order. Employees of mine and other sand handling industries showed significantly higher risks for cancer of stomach and cancer as a whole. Employees of the transportation industry showed the higher risk for cancer of liver, Workers in small-sized industry (${\leqq}100$) had a higher risk for cancer than who in large-sized industry (<100). These findings suggested the effect of occupational environmental exposure to cancer development.
김용식,Minkyung Bae,Dongsik Kong,Hyun Kwang Jung,Jaehyeong Kim,Woojoon Kim,Inseok Hur,김동명,김대환 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.21
The physical origins of the negative bias illumination stress (NBIS)-induced threshold voltage shift (VT ) in amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) under ambient light from a backlight unit are quantitatively and systematically investigated. Furthermore, a methodology for extracting the instability parameters is proposed and demonstrated. For the quantitative analysis, the subgap density-of-states (DOS)-based DC I-V model is intensively used. The NBIS time-evolution of the measured IDS-VGS characteristics is reproduced very well via the proposed methodology and instability parameters. Consequently, photo-excited electron detrapping, followed by ionization of oxygen vacancies (VO^(+2)) and field-enhanced VO^(+2) diffusion, followed by hole trapping into the gate insulator, are found to be the dominant mechanisms in NBIS-induced instability of a-IGZO TFTs.
심장근(心臟筋) mithochondria의 $Ca^{++}$유리에 대한 $Na^+$의 영향(影響)
김용식,박찬웅,김명석,Kim, Yong-Sik,Park, Chan-Woong,Kim, Myung-Suk 대한약리학회 1981 대한약리학잡지 Vol.17 No.1
Mitochondria로 부터의 $Na^+$에 의한 $Ca^{++}$유리현상은 digitalis의 강심기전을 설명하는데 있어 세포내 $Ca^{++}$농도 증가기전을 설명할 수 있는 현상의 하나로 보여지므로 $Na^+$에 의한 $Ca^{++}$유리와 이러한 $Ca^{++}$유리가 반응액내 $Ca^{++}$ 존재 유무로 어떠한 변화를 받는지를 비교 검토하였고 steady state에서의 $Ca^{++}$ flux에 대한 $Na^+$의 효과를 관찰하였다. $Na^+$의 증가에 따라 mitochondria에 흡수된 $Ca^{++}$의 유리량과 유리율이 증가하였고, EGTA 1mM 투여로 반응액내 잔여 $Ca^{++}$을 없을 경우 $Ca^{++}$유리가 증가함을 보여, 반응액내 잔여 $Ca^{++}$이 $Na^+$에 의한 $Ca^{++}$유리를 억제하리하 믿어진다. 한편 steady state에서 unidirectionai $Ca^{++}$ influx가 $Na^+$에 의하여 감소되는 점으로 미루어, $Na^+$에 의한 $Ca^{++}$유리는 $Na^+$이 $Ca^{++}-Ca^{++}$ 교환을 직접 억제하여 $Ca^{++}$ influx를 감소시켜 나타나는 결과로 생각된다. $Na^+$에 의한 unidirectional $Ca^{++}$ influx의 억제는 $Ca^{++}-Ca^{++}$교환에 $Na^+$이 직접 작용하며, 또한 반응액내 $Ca^{++}$의 다소에 따라 $Na^+$에 의한 $Ca^{++}$ 유리정도가 변화되는 양상으로 미루어 보아 mitochondria의 $Ca^{++}$ 운반의 일부는 $Na^+$과 $Ca^{++}$이 상경적으로 작용하는 모종의 동일매개체에 의하여 이루어질 수 있으리라 생각된다. The $Na^+$-induced calcium release and the effect of sodium on the transmitochondrial calcium flux were observed in mitochondria isolated from pig ventricular myocardium by Milipore filtration technique using radioisotope $^{45}Ca$. The release of calcium from cardiac mitochondria was induced by small amount of sodium, and was promoted by increasing sodium concentration in the incubation medium. The extent of the $Na^+$-induced calcium release was much greater in the absence of extramitochondrial calcium than in the presence of calcium. At steady state of calcium binding on the mitochondrial membrane unidirectional calcium influx was inhibited by sodium and unidirectional calcium efflux was increased., From the above results, it was suggested that calcium might be released from cardiac mitochondria in exchange with sodium through the mediation of the postulated '$Na^+/Ca^{++}$ exchange' mechanism.
Toluene의 생물학적 분해능 향상을 위한 계면활성제의 선정
김용식,손영규,김지형,송지현,Kim Yong-Sik,Son Young-Gyu,Khim Jee-Hyeong,Song Ji-Hyeon 한국지하수토양환경학회 2005 지하수토양환경 Vol.10 No.4
Surfactants can be used to enhance the mass transfer rate of hydrophobic compounds into the biologically active liquid phase, resulting in an increase in biodegradation rate of toluene. In this study, the mass transfer rate and the biocompatibility of toluene in the presence of various surfactants were evaluated. Four anionic and non ionic surfactants were tested: sodium dodecyl sulfate (SOS), TritonX-100, Tween 80, and BYK-345 (silicone surfactant). Experimental results showed that BYK-345 at the critical micelle concentration (CMC) enhanced the solubility of toluene. However, there was no increase in the solubility of toluene by SOS and TritonX-100 at their CMCs. With the addition of each surfactant into deionized water the mass transfer rate became faster than that of the case with no surfactant. A bottle study using toluene-degrading microorganisms showed that SOS seriously reduced toluene removal presumably due to the toxicity of the anionic surfactant and/or the substrate competition between the surfactant and toluene. In addition, the degradation rate of toluene was decreased in the presence of BYK-345, indicating that BYK-345 adversely affects the activity of microorganisms. However, TritonX-100 and Tween 80 did not decrease the degradation rate of toluene significantly. Rather, at the low concentration of TritonX-100 toluene degradation rate was even increased. Overall the experimental results suggest that TritonX-100 be the appropriate surfactant for enhanced biological degradation of toluene. 계면활성제는 소수성 물질(톨루엔)의 물질전달율을 증가시켜 미생물이 있는 액상으로 잘 녹아들어가게 함으로써 미생물에 의한 분해를 증가시킨다. 본 연구에서는 여러 종류의 계면활성제가 존재할 때 톨루엔의 물질전달율과 미생물에 의한 분해가 어떻게 이루어지는지에 대해 알아보았다. 사용한 계면활성제는 다음과 같다: Sodium Oodecyl Sulfate (SOS), TritonX-100, Tween 80, BYK-345 (silicone 계면활성제). 실험결과에 따르면 BYK-345는 critical micelle concentration (CMC)에서 톨루엔의 용해도를 증가시켰다. 하지만, SDS와 TritonX-100는 CMC에서 톨루엔의 용해도를 증가시키지 못했다. 증류수에 계면활성제를 첨가하면 증류수만 있는 경우보다 톨루엔의 물질전달율$(K_La)$이 증가했다. 톨루엔 분해 미생물을 이용한 회분식 실험에서 SOS는 톨루엔의 분해를 감소시켰다. 그 이유는 SDS가 미생물에 독성을 미쳤기 때문일 수도 있고, 기질로서 이용되어서 톨루엔과 경쟁관계에 놓였기 때문일 수도 있다. BYK-345를 계면활성제로 사용한 실험에서도 톨루엔의 분해가 감소했는데 이것은 BYK-345가 미생물의 활성도에 심각한 영향을 미쳤기 때문이다. 하지만, TritonX-100 와 Tween 80의 경우에는 톨루엔의 분해가 크게 감소하지 않았다. 낮은 농도의 TritonX-100의 경우에 오히려 톨루엔의 분해는 증가했다. 이와 같은 결과들을 통해 톨루엔의 생물학적 분해를 위해 가장 적절한 계면활성제는 TritonX-100임을 알 수 있었다.