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Choi, J.S.,Park, S.D.,Jun, B.H.,Han, Y.H.,Sung, T.H.,Choo, K.N.,Kim, C.J. The Korean Society of Superconductivity and Cryoge 2009 한국초전도저온공학회논문지 Vol.11 No.2
Effects of $BaCO_3$ purity on the superconducting properties of top seeded melt growth (TSMG) processed $Y_{1+x}Ba_2Cu_3O_{7-y}$ (Y1+x, x=0.1 and 0.2) superconductors were investigated. $YBa_2Cu_3O_{7-y}$ (Y123) powder prepared using $BaCO_3$ with 99.75% purity and commercially available Y123 powder of 99.9% were used for the fabrication of single Y123 grain superconductors. $T_c$ values of the Y1+x samples prepared using low purity Y123 powder were slightly lower than those of the samples prepared using a high purity powder. In addition to the lower $T_c$, an anomalous peak effect in the intermediate magnetic fields was observed in Y1+x samples prepared using the low purity $BaCO_3$ powder. The slight decrease in $T_c$ and the anomalous peak effect are ascribed to the possible incorporation of a Y123 phase with impurity elements such as strontium and calcium included in the $BaCO_3$powder of 99.7%. The result suggests that the low purity $BaCO_3$ powder of a low price can be used as a raw power for the fabrication of single grain YBCO bulk superconductors.
Choo, S.,Um, Y.,Han, S.O.,Woo, H.M. Elsevier Science Publishers 2016 Journal of biotechnology Vol.224 No.-
<P>The possibilities to utilize one-carbon substrates (C-1) like CO, methane and methanol have been explored as a cheap alternative feedstock in the biotechnology. For the first time, methyl acetate (MeOAc), which can be formed from carbonylation of methanol with CO, was demonstrated to be an alternative carbon source for the cell growth of Corynebacterium glutamicum as a model microbial cell factory. To do so, a carboxyl esterase activity was necessary to hydrolyze MeOAc to methanol and acetate. Although the wild-type has an unknown esterase activity to MeOAc, the activity was not high enough to grow from 270 mM MeOAc as sole carbon source, reaching OD600 of 5.28 +/- 0.2 in 32 h. Based on the literatures studied for the esterase, we chose three esterases (MekB of Pseudomonas veronii MEK700, AcmB of Gordonia sp. Strain TY-5, and Est of Pyrobaculum calidifontis VA1) and cloned into the wild-type. As a result, the recombinant C. glutamicum expressing the highly active MekB esterase (28.6 +/- 0.77 U/mg protein) showed complete degradation of MeOAc and utilization of acetate, resulting in OD600 of 16.5 +/- 0.02 at 24 h. In addition, the recombinant strain exhibited the rapid degradation of MeOAc to methanol and acetate in 2 h under anaerobic condition. Therefore, MeOAc can be used as another C-1-derived carbon source in the biotechnology. (C) 2016 Elsevier B.V. All rights reserved.</P>
김근수,추고연,김태환,성재석,이용택,오숭호,이민수,최호상 한국공업화학회 2003 응용화학 Vol.7 No.1
Zeolite membrane was produced by hydrothermal synthesis on α ̄alumina substrate using clear solution method. Zeolite membrane can separate liquid phase reactants like a water/mehtanol system. The compogition ratio of raw materials. 90 Na_2O : 1 Al_2O_3 : 9 SiO_2 : 5760 H_2O was used for preparation of zeolite membrane. The deposition states of zeolite crystal on alumina substrate by change of aging time were analysed through XRD and SEM.
Evaluation of Boar Sperm Viability by MTT Reduction Assay in Beltsville Thawing Solution Extender
Byuna, J.W.,Choo, S.H.,Kim, H.H.,Kim, Y.J.,Hwang, Y.J.,Kim, D.Y. Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.4
MTT (3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) reduction assay is a method that validates the viability of an active cell. Dehydrogenase in mitochondria converts yellow colored insoluble tetrazolium salt to purple colored water-soluble formazan. Sperm also have mitochondria in the midpiece, therefore sperm viability could be evaluated by MTT reduction assay. Several studies have already demonstrated the capability of application of the MTT reduction assay to sperm of several species in Hepes-BSA buffer. Because most liquid semen was diluted in extender like BTS (Beltsville Thawing Solution), Modena or Androhep when it is used or transferred, semen needed another dilution in Hepes-BSA buffer to assess sperm viability. In this study, we evaluated boar sperm viability especially in BTS extended semen and compared the efficiency of this test with eosin-nigrosin staining. We used the fresh BTS extended semen from a local A.I center. Semen sample was diluted to $3.0{\times}10^7$ sperms/ml in BTS. The rates of formazan production were measured in 96-well microtiter plates immediately and 1h after incubation at $17^{\circ}C$ using a spectrophotometer at wave length 560 nm. Simultaneously, split samples of the same semen were tested, using eosin-nigrosin staining to compare the efficiency of the MTT assay of sperm viability in BTS. The correlation between the results of these tests was calculated using Student-t test and ANOVA. The results revealed a strong correlation between the results of MTT reduction rate and the results that were simultaneously determined by eosin-nigrosin staining at 1 h. In conclusion, the MTT reduction test was an effective and simple method to validate sperm viability and it could be used as a simple tool to evaluate sperm viability in the local A.I center and laboratory.
Perovskite계 La_(0.9)Sr_(0.1)(Ga_(1-x)Fe_(x))_(0.8)Mg_(0.2)O_(3- δ) 의 제조 및 특성
추고연,김태환,김권일,Politova, E. D.,성재석 한국공업화학회 2004 응용화학 Vol.8 No.1
In this paper, perovskite-type La_(0.9)Sr_(0.1)(Ga_(1-X)Fe_(X))_(0.8)Mg_(0.2)O_(3-6)(x=0-0.5) powders were prepared by solid state reaction, followed by estimation of phase structures and properties according to Fe contents and sintering conditions. Impurity phases as well as perovskite phase were observed in the powders which were calcined at 800℃ for 10h followed by sintering at 1300℃ for 10h. The smallest amount of the impunrity phases was observed in the powder with the highest Fe content. The X-ray diffraction peaks corresponding to the 220 peak in pseudo cubic lattice were collected. The data were used for calulation of orthorhombic unit cell parameters by PROFITVZ program. Mean unit cell parameters(V^(1/3)) decreased with x at the Fe contents not more than 0.2 and increased with x at the Fe contents not less than 0.3. Electrical conductivity of the bar-like samples was measured as a function of temperature from 290K up to 1200K in air by a standard two-probe technique using platinum electrodes. The relationship between lot(oT) and l/T as lkHz exhibited the Arrhenius behavior, Electrical conductivity increased with Fe contents. Particularly, Fe contents substantially contributed to electrical conductivity at lower temperature. In air, La_(0.9)Sr_(0.1)(Ga_(0.75)Fe_(0.25))_(0.8)Mg_(0.2)O_(3-6) perovskie-type oxide showed the reversible elongation property in which the structural phase transition occurred at near 600℃.
조희진,김용성,장옥배 全北大學校 基礎科學硏究所 1991 基礎科學 Vol.14 No.2
ICAI 시스템은 CAI 시스템의 한계를 극복하기 위하여 학생 개개인의 능력과 지식정도를 파악하여 개인차에 따라 보다 효율적으로 학습할 수 있는 것을 말하는데 기존의 ICAI 시스템은 단일 지식 영역에 대한 학생 모델을 이용함으로써 학습자의 개인차에 관한 적성 변인을 파악하는 데 어려움이 있고 그러한 이유로 해서 학습자에 대한 교수 전략을 실시할 수 있는 정보 지식이 미흡하였다. 개선된 ICAI 시스템은 지식 베이스를 이용하여 보다 효율적인 교수 전략과 학생 모델을 가능하게 할 수 있는 시스템이다. 본 연구에서는 개선된 ICAI 시스템의 구조와 이들 각각의 기능 및 특징에 관하여 살펴보았다.
한국산 발효식품 미생물이 분비하는 Aflatoxin에 관한 연구
이배함,전영연,최태주,주현규,김상재,정성구 건국대학교 1971 學術誌 Vol.12 No.1
One hundred and seventeen strains of the genus Aspergillus isolated from 486 fermented foodstuffs which have been collected widely in the country, and the isolated strains were classifiedinto15 species, A. flavus, A. oryzae, A. kawachii, A. niger. A. versiolor, A. parasiticus, A. fumigatus, A. usamii, A. sulphureus, A. clavatus, A. carbonarius, A. pulverulentus, and A. nidulans. The fifteen strains of A. flavus which isolated from fermented soybean foodstuffs, were cultured in Adye and Mateles Medium and the productivity of aflatoxin was studied by fluorometry and thin layer chromotography, using the aflatoxin producing strain ATCC 17715 as a control. On the thin layer chromatograms, there were spots corresponding to aflatoxins, but on the ultra violet absortion spectra, none of the absorption curve of elution of the spots shows accordance with the curve of the control aflatoxin.