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Kim, M-J,Kang, J-H,Park, Y G,Ryu, G R,Ko, S H,Jeong, I-K,Koh, K-H,Rhie, D-J,Yoon, S H,Hahn, S J,Kim, M-S,Jo, Y-H Journal of Endocrinology, Ltd. [etc.] 2006 The Journal of endocrinology Vol.188 No.3
<P>Glucagon-like peptide-1 (GLP-1) and its analog exendin-4 (EX) have been considered as a growth factor implicated in pancreatic islet mass increase and beta-cell proliferation. This study aimed to investigate the effect of EX on cyclin D1 expression, a key regulator of the cell cycle, in the pancreatic beta-cell line INS-1. We demonstrated that EX significantly increased cyclin D1 mRNA and subsequently its protein levels. Although EX induced phosphorylation of Raf-1 and extracellular-signal-regulated kinase (ERK), both PD98059 and exogenous ERK1 had no effect on the cyclin D1 induction by EX. Instead, the cAMP-elevating agent forskolin induced cyclin D1 expression remarkably and this response was inhibited by pretreatment with H-89, a protein kinase A (PKA) inhibitor. Promoter analyses revealed that the cAMP-responsive element (CRE) site (at position -48; 5'-TAACGTCA-3') of cyclin D1 gene was required for both basal and EX-induced activation of the cyclin D1 promoter, which was confirmed by site-directed mutagenesis study. For EX to activate the cyclin D1 promoter effectively, CRE-binding protein (CREB) should be phosphorylated and bound to the putative CRE site, according to the results of electrophoretic mobility shift and chromatin immunoprecipitation assays. Lastly, a transfection assay employing constitutively active or dominant-negative CREB expression plasmids clearly demonstrated that CREB was largely involved in both basal and EX-induced cyclin D1 promoter activities. Taken together, EX-induced cyclin D1 expression is largely dependent on the cAMP/PKA signaling pathway, and EX increases the level of phosphorylated CREB and more potently trans-activates cyclin D1 gene through binding of the CREB to the putative CRE site, implicating a potential mechanism underlying beta-cell proliferation by EX.</P>
C-2와 C-2,4 위치에 치환된 8-aza-bicyclo[3.2.1]octan-3-one 유도체 합성 및 구조분석
정대일,이도훈,송주현,이용균,최순규,박유미,한정태 동아대학교 환경문제연구소 2006 硏究報告 Vol.28 No.1
The tropane ring system is an important substructure in a number of natural products and synthetic compounds of biological and medicinal importance. As a result of the significance of the tropane ring system, the purpose of this study is the synthesis of anticonvulsant compounds of new structure anticipated anticonvulsant activity. After we first synthesized the various N- substituted 8-aza-bicyclo[3.2.1]octan-3-one derivatives. We prepared now 2-substituted nortropinones. 2-Substituted 8-aza- bicyclo [3.2.1]octan-3-ones were obtained from diluted NaOH concentration(0.01N NaOH) in similar method of synthesis of 2,4-disubstituted 8-aza-bicyclo[3.2.1]octan-3-ones 23, 24, 25 were respectively synthesized by the reaction of corresponding N-substituted 8-aza-bicyclo[3.2.1]octan-3-one with corresponding aldehyde in presence of 5N-NaOH solution in ethanol and dichloromethane at room temperature. Substantially, we tried several experiments to optimize reaction condition. Continuously, the synthesis and anticonvulsant activity evaluation of a new class of 8-aza-bicyclo[3.2.1]octan-3-one derivatives are in progress and will be reported in future.
Tropane Spirohydantoin들의 합성 및 구조분석
정대일,이도훈,송주현,이용균,최순규,박유미,한정태 동아대학교 환경문제연구소 2006 硏究報告 Vol.28 No.1
The tropane ring system is an important substructure in a number of natural products and synthetic compounds of biological and medicinal importance. As a result of the significance of the tropane ring system, the purpose of this study is the synthesis of anticonvulsant compounds of new s tructure anticipated anticonvulsant activity. After we first synthesized the various N-substituted nortropinone derivatives, we prepared new nortropane alkaloids and nortropinone derivatives. Substantially, we tried several experiments to optimize reaction condition. The tropane spirohydantoins 17, 18, 19, 20, 21 were respectively synthesized by the treatment of corresponding N-substituted nortropinone with potassium cyanide and ammonium carbonate.
Di-(N-tropinonyl)alkane들의 합성 및 구조 분석
송주현,정대일,이용균,최순규,박유미,한정태 東亞大學校 環境問題硏究所 2005 硏究報告 Vol.27 No.1
Di-(N-tropinonyl)alkanes (1,2-di-(8-aza-bicyclo[3,2,1]octan-3-onyl)ethane 12, 1,3-di-(8-aza-bicyclo[3,2,1]octan-3-onyl)propane 15, 1,8-di(8-aza-bicyclo[3,2,1]octan-3-onyl)octane 18) were prepared in the reaction of diaminoalkanes with 2,5-dimethoxytetrahydrofuran, and acetonedicarboxylic acid.
한영원(Y.W.Hahn),곽대영(D.Y.Kwak),임용택(Y.T.Im) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.6_2
In order to substitute steel for new material in fabrication of automotive hood, proper stiffness according to the constructed geometry should be guaranted. For this purpose, numerical analyses of self-weight deflection, oil canning test, and torsional deflection were carried out using steel and SMC (Sheet Molding Compound). For optimization of manufacturing cost and structural benefit, several geometries were considered for the arbitrarily selected hood design type. The current approach will be beneficial in determining the proper design parameters for fabrication of hood with new material such as composites or aluminium alloys.<br/>
안동규(D. G. Ahn),이상훈(S. H. Lee),김민수(M. S. Kim),한길영(G. Y. Hahn),정창균(C. G. Jung),양동열(D. Y. Yang) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
The objective of this research work is to investigate into characteristics of bending stiffness and failure for the ISB ultralightweight panel with internally structured material. The expanded metal with a pyramid shape and woven metal are employed as an internally structured material. In order to investigate the characteristics, the specific stiffness and failure map are estimated using the results of three-points bending test. From the results of the experiment, the influence of design parameters of ISB panel on the specific stiffness and failure mode has been found. In addition, it has been shown that ISB panel with expanded metal is prefer to that with woven metal from the view point of optimal design for ISB panel.
Ahn, D.G.,Lee, S.H.,Jung, C.G.,Hahn, G.Y.,Yang, D.Y. Elsevier 2007 Journal of materials processing technology Vol. No.
<P><B>Abstract</B></P><P>The objective of this paper is to investigate the influence of design parameters of the ISB panel, an inner structured and bonded panel with metallic pyramidal inner structures, on mechanical properties and failure characteristics to obtain the optimum design of the ISB panel. Several experiments and analyses for the case of tensile and three-points bending load have been carried out to examine the influence of the crimping angle and sizes of the ISB panel on characteristic properties, including the specific stiffness and the specific strength, the deformation behavior and failure characteristics. From the results of the experiments and analyses, relationships between crimping angle and the specific stiffness and characteristics of the deformation according to the crimping angle have been obtained. In addition, a failure map of the ISB panel has been created to estimate the effects of the design parameters on the failure mode. Based on the above results, it has been shown that the ISB panel with a metallic pyramidal inner structure can be optimally designed by control of the crimping angle for the pyramidal structure.</P>
Kinetic Studies of β - D - Galactosidase Inactivation
Kim, D. H.,Hong, S. K.,Hahn, Y. H. 생화학분자생물학회 1987 BMB Reports Vol.14 No.2
An improved method of determining the initial velocity of an enzyme inactivation was successfully applied to the kinetic study of β-D-galactosidase (E.C. 3.2.1.23.) inactivation concerning pH and the enzyme concentration. The pH inactivation of β-D-galactosidase could be explained by the inactivation model of ricin proposed by Levy and Benaglia. The double sigmoid curve of the initial velocity of inactivation with respect to pH made it possible to assume 5 intermediates of ionized enzyme form. From this it could be concluded that 4 of the 7 ionizable amino acid side chains of β-D-galactosidase contribute to the conformational stability of this enzyme. Dimerization of the tetramer enzyme molecule to form an octamer was found and it was supported by the sedimentation study of Loontiens et al. and by the kinetic study of this research. At very low enzyme concentration less than 1 ㎍ protein per ㎖, the inactivation was simple unimolecular reaction, but in a moderate enzyme concentration such as 10 ㎍ protein per ㎖, the reacton order of inactivation increased to about 2. Second order inactivation of β-D-galactosidase might be resulted from the disulfide bond formation between the tetramer enzyme molecule and consequently to dissociate the octamer inactive monomers. And there are much evidences supporting the existence of trigering value of conformational change in each subunit to cause the polymer dissociation.