균열이 없는 균일한 다공질 유리의 특성과 제조

류봉기,이승한,한덕희 釜山大學校生産技術硏究所 1998 生産技術硏究所論文集 Vol.55 No.-

역삼투압, 초여과 공정, 광학 렌즈 등에 응용되는 균열이 없는 다공질 유리를 개발하기 위하여, 붕규산 소다 유리로부터 상분리법 의한 다공질 유리 제조과정에 있어서 분상 열차리 및 용출조건과 조성이 이들 유리의 특성에 미치는 영향을 조사하였다. 균열이 없는 다공질 유리는 높은 silica 함유의 모유리와 낮은 온도 범위(540∼560℃)에서 30h 이상 열처리 후 0.1∼0.3N H₂SO₄ 용액으로 100℃에서 25h 이상 용출시켰을 때 제조 가능하였다. To produce the crack-free porous glass used for the reverse osmosis, hyperfiltration process and optic al lense, porous glass was prepared from the sodium borosilicate parent glass by the phase-separation technique. Effects of heat treatment, leaching condition, and chemical composition in the smaples were investigated. The crack-free porous glass could be fabricated from high-silica parent glass heat-treated at(540∼560℃) for above 30h, then leached with 0.1∼0.3N H₂SO₄solution at 100℃ for above 25h.

Phosphate 유리들의 구조-물성-조성 상관에 대한 연구

류봉기,이승한,이병철 釜山大學校生産技術硏究所 1998 生産技術硏究所論文集 Vol.55 No.-

P₂O -Na₂O-MgO, P₂O-Na₂O 및 P₂O-MgO glass 계에서 조성에 따른 구조변화를 조사하기 위해 glass의 밀도와 물에 대한 안정성 그리고 Raman 과 적외선 흡수 스펙트럼이 측정되었다. 그 결과, P₂O가 60mol% 부근에서 밀도와 물에 대한 안정성의 급격한 증가를 나타내었다. 이러한 변화는 Mg²+ 이온을 중심으로 DBO(double-bonded oxygen)이 배위하면서 glass 구조의 강한 수축을 유발시켜 나타난 구조변화에 기인하는 것으로, Mg²+ 이온을 배위하고 있는 DBO은 이중결합의 성격을 잃어버리고, 다른 하나의 NBO(non-bridging oxygen)과 함께 공명을 일으킨다고 생각된다. Raman, infrared spectroscopy, dnesity, and water resistance in P₂O-Na₂O-MgO, P₂O-Na₂O and P₂O-MgO glass systems were measured to investigate the structural change depending on their composition. The density and water resistance showed an abrupt increase in the range of about 60mol% P₂O. These results can be explained by the structural changes owing to the strong shrinkage of glass network which is caused by the coordination of DBO(double-bonded oxygen) around Mg²+ cations i.e. it seems that the DBOs coordinating Mg²+ cations, losing their characteristics of double bonding, will resonate with other NBOs(non-bridging oxygen).

반도체 미립자를 함유한 Silica Glass의 제조 및 특성

류봉기,이승한,임재호 釜山大學校生産技術硏究所 1998 生産技術硏究所論文集 Vol.55 No.-

본 연구에서는 Sol-Gel법을 이용하여 우수한 양자 사이즈 효과를 가진 ZnS를 함유한 실리카 유리를 제조하였다. 출발 물질로서 Si(OC₂H)₄와 Zn(CH₃COO)₂·2H₂O를 사용하여 무색 투명한 겔을 제조하였다. 얻어진 겔을 600℃에서 열처리를 하여 상온에서 H₂S gas와 반응시켜 유리 내에 ZnS 미세결정을 형성시켰다. ZnS 미립자의 밴드갭 에너지 3.71∼4.27eV였는데 이 값은 벌크상 ZnS의 밴드갭보다 약 0.1∼0.5eV 더 높은 수치를 나타내었다. ZnS 미세결정의 크기는 EMA(Effective Mass Approximation)에 의해 구하였는데, 이는 ZnO의 투여량과 H₂S gas와의 반응시간에 따라 변화하였다. ZnS 미세결정의 크기가 증가함에 따라, 광흡수단은 낮은 에너지영역으로 이동하였는데, 이 현상은 양자 사이즈 효과를 보여주고 있다. In this study, Sol-Gel process has been applied to make ZnS-doped silica glass having a significant quantum size effect. Si(OC₂H)₄ and Zn(CH₃COO)₂·2H?O were used to prepare transparent and colorless gels. These gels were heated at 600℃, then reacted with H₂S gas to form fine ZnS microcrystals in glasses. The opical band gap of the ZnS microcrystals was 3.71∼4.27eV, which was 0.1∼0.5eV higher than that of bulk ZnS crystal. The size of ZnS microcrystals calculated by EMA(Effective Mass Approximation) in glasses changed with ZnO concentration and H₂S gas reaction time. As the size of the ZnS microcrystal increased, the absorption edge of spectra shifted to the low-energy side, thus providing quantum size effect.

사람 YB-1 유전자의 프로모터에 결합하는 핵인자에 관한 연구

김유리,한상원,류필열,김경근,안봉환,신부안 全南大醫大 2001 전남의대학술지 Vol.37 No.1

지방산 유지 원료에 따른 고형비누의 특성에 관한 연구

정명선,배한수,이봉연,민경혜,류덕환 계명대학교 생활과학연구소 2001 科學論集 Vol.27 No.-

The experimental results on the washing efficiency of detergent made from corn oil, wasted cooking oil and pig fat oil are as follows ; Laundry factors in this experiment are detergent concentration, laundry temperature and laundry time. 1.The surface tension of each detergent showed the lowest in 0.2% concentration corn oil 60.84, wasted cooking oil 61.11, pig fat oil 60.73dyne/cm. 2.The wasthing efficiency based on different concentration of detergents showed the highest in 0.2% concentration. 3.The highest washing efficiency appeared in 0.2% concentration 40℃ temperature and 40~50 min. time. There showed no difference in the washing efficiency according to the volume of water. It can be said that the frictional force of bearing rather than the volume of water worked on the efficiency.

Fermentation Conditions for the Production of Cell Mass in Streptococcus faecalis and Endospores in Bacillus mesentericus

현형환,김부연,류한봉 한국외국어대학교 외국학종합연구센터 부설 기초과학연구소 1996 기초과학연구 Vol.4 No.-

Streptococcus faecalis는 glucose, lactose등을 탄소원으로 잘 이용하였으며 glucose를 탄소원으로, yeast extract와 casitone을 질소원으로 구성된 배지를 사용하여 pH 7.0에서 control되는 fermentor 배양에서 optical density(660nm) 7.3(viable cell concentration 6.5×10(9) cells/㎖)이상의 높은 cell concentration을 얻을 수 있었다. Bacillus mesentericus의 sporulation을 최대화 하기 위한 발효 조건을 조사한 결과 glucose를 위한 최적 CaCl₂농도는 0.lmM이었다. Streptococcus faecalis rapidly fermented glucose and lactose as a C-source, and the maximum cell concentration was obtained when grown in a jar fermentor that contained YCG medium consisting of glucose as a C-source and casitone and yeast extracts as a N-source, and that was controlled at pH 7.0. From experiments to maximize the sporulation efficiency in Bacillus mesentericus, glucose caused the decrease in sporulation efficiency, and calcium chloride was stimulatory for sporulation, of which optimum concentration was 0.lmM.

사람 뇌척수액중 Transthyretin의 항산화작용

양성렬,최기오,박종근,류문희,홍석노,김수한,안봉환,이제혁,이민화 대한신경외과학회 1994 Journal of Korean neurosurgical society Vol.23 No.4

Protective effects of human cerebrospinal fluid antioxidants against enzyme inactivation caused by metal-catalyzed oxidation systems were investigated. When purified glutamine synthetase(GS) was incubated with human cerebrospinal fluid(CSF), the enzyme was progressively inactivated. Catalase and EDTA could inhibit the enzyme inactivation by 50-80%. Small-molecular(Mr< -10,000) fraction of CSF inactivated the exogenous GS, but large-molecular(Mr> -10,000) fraction did not. The GS inactivation by the small-molecular fraction was also markedly inhibited by catalase and EDTA. These results suggested that metal-catalyzed oxidation is involved in the GS inactivation by the small-molecular fraction of CSF. Dithiothreitol(DTT) was shown to inhibit almost completely the oxidative inactivation of GS by CSF. However, DTT inhibited only partially the oxidative inactivation of GS caused by small-molecular fraction of CSF. When large-molecular fraction of CSF was separated by anion-exchange HPLC chromatogrpahy, there was a peak of antioxidant activity inhibiting the small-molecular fraction-induced GS inactivation in the presence of DTT. The antioxidant activity was neutralized by monoclonal antibodies to transthyretin. Purified transthyretin was found to efficiently inhibit ascorbate/Cu^(2+)-induced GS inactivation in the presence of DTT. Uric acid and glucose did not show any protective effect on the GS inactivation in the same condition. The above results suggest that metal-catalyzed oxidation occurs normally in human CSF, and that transthyretin may play an important role as a CSF antioxidant in protecting proteins from metal-catalyzed oxidation.

YlaC is an Extracytoplasmic Function (ECF) Sigma Factor Contributing to Hydrogen Peroxide Resistance in Bacillus subtilis

Ryu Han-Bong,Shin In-Ji,Yim Hyung-Soon,Kang Sa-Ouk The Microbiological Society of Korea 2006 The journal of microbiology Vol.44 No.2

In this study, we have attempted to characterize the functions of YlaC and YlaD encoded by ylaC and ylaD genes in Bacillus subtilis. The GUS reporter gene, driven by the yla operon promoter, was expressed primarily during the late exponential and early stationary phase, and its expression increased as the result of hydrogen peroxide treatment. Northern and Western blot analyses revealed that the level of ylaC transcripts and YlaC increased as the result of challenge with hydrogen peroxide. A YlaC-overexpressing strain evidenced hydrogen peroxide resistance and a three-fold higher peroxidase activity as compared with a deletion mutant. YlaC-overexpressing and YlaD-disrupted strains evidenced higher sporulation rates than were observed in the YlaC-disrupted and YlaD-overexpressing strains. Analyses of the results of native polyacrylamide gel electrophoresis of recombinant YlaC and YlaD indicated that interaction between YlaC and YlaD was regulated by the redox state of YlaD in vitro. Collectively, the results of this study appear to suggest that YlaC regulated by the YlaD redox state, contribute to oxidative stress resistance in B. subtilis.

종동력을 받는 외팔 Timoshenko보의 동적안정성에 미치는 부분탄성기초의 영향

류봉조(Bong-Jo Ryu),류시웅(Si-Ung Ryu),한현희(Hyun-Hee Han),김효준(Hyo-Jun Kim) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4

The paper deals with the dynamic stability of a cantilevered Timoshenko beam on partial elastic foundations subjected to a follower force. The beam is assumed to be a Timoshenko beam with a concentrated mass taking into account its rotary inertia and shear deformation. Governing equations are derived by extended Hamilton's principle, and FEM is applied to solve the discretized equation. Critical follower force depending on the attachment ratios of partial elastic foundations, concentrated mass and rotary inertia of the beam is fully investigated.

Effect of Gamiondam-tang (GMODT), a Polyherbal Formula on the Pharmacokinetics Profiles of Tamoxifen in Male SD Rats

Ryu, Eun-A,Kang, Su-Jin,Song, Chang-Hyun,Lee, Bong-Hyo,Choi, Seong-Hun,Han, Chang-Hyun,Lee, Young-Joon,Ku, Sae-Kwang The Society of Korean Medicine 2017 대한한의학회지 Vol.38 No.2

Objectives: The effects of Gamiondam-tang (GMODT) co-administration within 5min on the pharmacokinetics (PK) of tamoxifen were observed as a process of the comprehensive and integrative medicine, combination therapy of tamoxifen with GMODT to achieve synergic pharmacodynamics and reduce toxicity on the breast cancer. Methods: After 50mg/kg of tamoxifen treatment, GMODT 100mg/kg was administered within 5min. The plasma were collected at 30 min before administration, 30 min, 1, 2, 3, 4, 6, 8 and 24 hrs after end of GMODT treatment, and plasma concentrations of tamoxifen were analyzed using LC-MS/MS methods. PK parameters of tamoxifen (Tmax, Cmax, AUC, $t_{1/2}$ and $MRT_{inf}$) were analysis as compared with tamoxifen single administered rats using noncompartmental pharmacokinetics data analyzer programs. Results: Co-administration with GMODT induced increased trends of plasma tamoxifen concentrations to 1hr after end of administration, and then showed decreased trends of plasma tamoxifen concentrations, and especially significant (p<0.05) increases of plasma tamoxifen concentrations were demonstrated at 0.5hr after end of co-administration with GMODT and also related significant (p<0.05) decreases of $AUC_{0-inf}$ and $MRT_{inf}$ as compared with tamoxifen single formula treated rats, at dosage levels of tamoxifen 10 mg/kg and GMODT 100 mg/kg within 5 min, in this experiment. Conclusion: Based on the results of the present study, it is considered that single co-administration GMODT within 5min significantly inhibited the oral bioavailability of tamoxifen through variable influences on the absorption and excretion of tamoxifen, can be influenced on the toxicity or pharmacodynamic of tamoxifen.