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동형 모더나이트 상에서 일산화탄소 산화반응에 대한 속도론
정명수,이창용,최고열,하백현 漢陽大學校 環境科學硏究所 1989 環境科學論文集 Vol.10 No.-
모더나이트에 동을 이온교환 및 담지시킨 후 환원·산화 처리를 하여 동의 상태를 변화시킨 촉매에 대해 일산화탄소 산화반응의 속도론적인 고찰을 행하였다. 이온교환 촉매나 담지촉매 모두 동의 상태와는 관계없이 일산화탄소에 관한 반응차수는 1차이고 산소에 관한 반응차수는 0차였다. 이온교환 촉매의 경우는 수소로 환원시켜 동이 금속상태로 존재할때와 이를 재산화시켜 산화동 상태로 존재할때는 활성화에너지가 각각 16.4 및 20.3으로 비교적 큰 값을 나타냈으나 동의 담지촉매의 경우는 동이 금속일 때나 산화물 상태 모두 12∼13kcal/mole로 비슷한 값을 나타냈으며 이온교환 촉매보다 상당히 감소함을 알 수 있었다. 이와 같은 결과는 이온교환 촉매의 경우는 동이 제올라이트내부에 대부분 존재하는 반면, 담지촉매의 경우는 제올라이트 결정 표면에 존재하기 때문에 활성을 증가시키는 것으로 생각된다. Kinetics of oxidation of carbon monoxide over copper mordenite was carried out at the temperature range between 373K-443K in the micro-catalytic reactor. The experimental results indicated that the reaction order, with respect to carbon monoxide and oxygen was first and zero order respectively, regardless of the valence states such as copper metal, copper ion and copper oxide on the mordenite. The activation energy for metal-copper mordenite which is obtained by the ion-exchange revealed 20kcal/mol. But if this was reoxidized under the oxygen it decreased to 16.6kcal/mol. The activation energy of metal-copper mordenite which was obtained by impregnation and its reoxidized one under the oxygen were 12.2kcal/mol and 13.3kcal/mol respectively.
고분자 전해질형 연료전지에서 Hot Pressing 조건의 영향
이태희,이승재,조원일,노용우,고영태,최경환 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.1
고분자 전해질형 연료전지에서 고분자막/전극 어셈블리를 hot pressing 조건을 달리하여 제조하고 그 성능을 반응면적 5㎠인 단위전지에서 측정하였다. 전지의 성능은 고분자막과 전극간의 접합이 가능한 온도 범위에서 hot pressing온도가 낮을수록, hat Pressing 압력이 높을수록 향상되었다. 즉, 고분자 전해질형 연료전지의 성능은 고분자 전해질 내의 수분 함량 증가, 고분자막/전극간 접촉저항 감소 및 얇은 고분자막을 사용한 전해질의 이온저항 감소 등으로 향상시킬 수 있었다. For a proton exchange membrane fuel cell, membrane and electrode assemblies were fabricated by different hot pressing conditions and those performances were observed in a unit cell having 5 ㎠ active electrode area. The cell performance increased with lower hot pressing temperature in the range of temperature having intimate contact between membrane and electrodes and with higher hot pressing pressure. Namely, the performance of proton exchange membrane fuel cell could be raised with higher water content in the membrane, with lower contact resistance between membrane and electrodes and with lower ion resistance of the electrolyte using thinner membrane.
Path intersection matrices and applications to networks
Kho, D.Y.,Kook, W.,Lee, J.,Lee, J.,Lee, K.J. North Holland [etc.] 2017 Linear algebra and its applications Vol.524 No.-
<P>For a network G, we introduce a non-singular symmetric matrix, called a path intersection matrix, that will provide a new method for computing the ratio k(G)/k(G/ab) where k(G) is the tree-number of G and G lab is obtained from GUab by contracting the new edge ab between two distinct nodes a and b. The quantities k(G)/k(G/ab) appear as invariants for various networks such as effective conductance for an electrical network and an ingredient for information centrality for a social network. We will review several examples of networks where path intersection matrices can be applied. (C) 2017 Elsevier Inc. All rights reserved.</P>
Effects of Cryoprotectants and Freezing Rates on Cryopreservation of Catfish, Silurus asotus Sperm
Kho, Kang Hee,Kang, Kyoung Ho The Korean Society of Fisheries and Aquatic Scienc 2004 韓國養殖學會誌 Vol.17 No.1
Milt of the catfish was stripped into immobilizing solution containing 175 mM NaCl and 30 mM Tris at pH 7.8 and was successfully cryopreserved after a stepwise freezing procedure. After stepwise thawing, motility of spermatozoa was slightly lower than that of fresh sperm. Batches of 40-80 eggs were fertilized with cryopreserved spermatozoa, after thawing and activation in solution containing 50 mM NaCl, 20 mM Tris and HCl at pH 7.8; this resulted in 62.2% fertilization success, compared to 70.6 % with fresh sperm.
A report of three unrecorded Ovulid species (Gastropoda, Heterodonta) from Korea
Kho, Dong-Bum,Lee, Jun-Sang,Min, Duk-Ki The Malacological Society of Korea 2015 The Korean Journal of Malacology Vol.31 No.1
Three Ovulid species collected from Jeju Island were identified as Habuprionovolva aenigma (Azuma & Cate, 1971), Habuprionovolva basilia (Cate, 1978) and Diminovula kosugei (Cate, 1973). This is the first record from the Korean waters, providing a description of the species with illustration for the shell morphology.
Kho, Minjung,Lee, Jung Eun,Song, Yun-Mi,Lee, Kayoung,Kim, Kyunga,Yang, Sarah,Joung, Hyojee,Sung, Joohon American Society for Clinical Nutrition 2013 The American journal of clinical nutrition Vol.98 No.6
<P><B>Background:</B> Salt is essential in our diet, but excess intake is a well-established risk factor for hypertension. The presence and importance of genetic contributions to salt intake, however, are not well understood.</P><P><B>Objective:</B> The aim of this study was to examine whether a genetic predisposition and an environmental influence exist for sodium intake and salt habit.</P><P><B>Design:</B> In a twin-family cohort, half-day urine samples from 1204 individuals (133 pairs of monozygotic twins, 29 pairs of dizygotic twins, and 880 singletons) were collected to assess 24-h sodium intakes. Daily total sodium intake, sodium density per calorie (Na-D), and salt habit questions were analyzed with adjustment for other epidemiologic characteristics. We calculated heritability (h2) and intraclass correlations to examine the genetic and shared environmental contributions to total sodium intake traits.</P><P><B>Results:</B> The average sodium intake was 208.4 ± 107.0 mmol/d. Men had a higher absolute sodium intake (242.6 ± 117.4 mmol/d), but Na-D did not differ by sex. Moderate genetic influences existed (h2 = 0.31–0.34) for sodium intake and Na-D. We also found that sharing current residence rather than being a family member explained 22% of the variance in Na-D.</P><P><B>Conclusion:</B> Our findings suggest that both genetic predisposition and shared environment contribute to sodium intakes and salt habits alike.</P>