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임세환,송춘삼,홍석관,강정진,김주현 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-
A plane strain finite element model is developed to simulate turning with continuous chip formation using adaptive remeshing during the thermal-mechanical coupled analysis. Comparisons between the experimental and simulation results for cutting forces are performed to validate FE analysis results. Influences of machining parameters such as depth of cut, cutting speed and feed rate on cuting force and shear angle are analyzed by Taguchi method. The more depth of cut and feed rate result in the increase of cutting forces, but the rates of increase are decrease due to the larger shear angle. As the cutting speed increases, von Mises stress of workpiece near the tool tip decreases because the strength of specimen decreases at high temperature above 500℃. This thermal effect on cutting force is negligible because the affected area is very localized and the average values of von Mises stress in the shear plane are the same among the diverse cutting parameters.
성인식,임세환,김주현 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-
Composite material is combined with two or more chemical ingredient and different components. FRP has been widely used for the structure of aircraft, ships, automobiles, sporting goods and other machines because of their high specific strength, high specific stiffness and excellent fatigue strength. Recently, the development of machine tool and cutting tool greatly relies on high speed process to satisfy high precision, high efficient machining, shortened process time to maximize material removal rate (MRR) through high cutting speed and feed speed. The research molded CFRP, GFRP as stacking sequence methods of two direction (orientation angle 0° and 0°/90°) hand lay-up, drilled molded plates using cemented carbide drill and examined chip shapes, surface roughness properties.
UV Absorbent, Marmesin, from the Bark of Thanakha, Hesperethusa crenulata L.
Joo, Se-Hwan,Lee, Sang-Cheol,Kim, Seong-Ki 한국식물학회 2004 Journal of Plant Biology Vol.47 No.2
We used solvent extractions, SiO₂ column chromatographies, and HPLC to isolate from the bark of Thanakha (Hesperethusa crenulata L) an active crystalline compound for absorbing UV-A radiation (320 to 380 ㎚). Analyses of low-and high-resolution FAB-MS revealed a compound, named marmesin, with a formula of C_(14)H_(14)O₄ and a molecular mass of 246. To determine its chemical structure, we conducted 300 MMz NMR analyses using various probes, ¹H, ^(13)C, and DEPT ^(13)C. Our NMR data showed a structure of 2,3-dihydro-2(1-hydroxy-1-methylethyl)-furanocoumarin. This active compound contains UV-absorbing chromophores, an aromatic ring, a double bond at C3-C4, and a carbonyl at C2. Its λ_(max) is 335 ㎚, indicating that marmesin could be commercially useful as a natural UV-A-filtering product.
Se-Hwan Joo,Jae-Sung Lee 한국무역학회 2021 Journal of Korea trade Vol.25 No.6
Purpose – This study analyzes the effects that the response to the technical barriers to trade (TBT), which are used by various countries as means to restrict imports, exerts on exports at a time when protectionism is emerging in the face of a global economic downturn. TBT has been widely used in developed countries for the safety and protection of their people. Recently, the use of TBT as a tool of protectionism has increased considerably in developing countries as well. Therefore, this study analyzes the South Korean SMEs’ response and export performance. Design/methodology – To analyze SMEs’ response to TBT and their export performance, this study conducted empirical analysis through statistical analysis. To this end, the research established a theory based on previous research and designed its hypothesis and research model. To verify the hypothesis and research model, factor analysis addressing validity and reliability was performed using SPSS 25 and AMOS 26, and the structural equation model was analyzed. Findings – This study found the causal relationship between the independent variable, the mediating variable, and the dependent variable adopted against the theoretical background to have little or no effect, in contrast with previous studies. In a break from previous studies, all hypotheses were rejected for innovation strategic competencies, one of the sub-factors of the independent variable, which is believed to be a result of the lack of practical research related to TBT. Originality/value – Previous studies performed analysis using trade statistics or macro data. A number of such studies analyzed the relationship between technical regulation and trade volume. This study differs from previous studies in some respects, because it analyzed the export performance of companies by establishing a hypothesis and implementing a research model with the factors analyzed in previous studies. In addition, a new attempt has been made by classifying the TBT response factors into technology competencies, human resource competencies, and innovation strategic competencies, and utilizing technology innovation and the export support system as mediating effects.
Joo, Se-Hwan,Kim, Tae-Wuk,Son, Seung-Hyun,Lee, Woo Sung,Yokota, Takao,Kim, Seong-Ki Oxford University Press 2012 Journal of experimental botany Vol.63 No.5
<P>A metabolic study revealed that 28-norcastasterone in <I>Arabidopsis</I> is synthesized from cholesterol via the late C-6 oxidation pathway. On the other hand, the early C-6 oxidation pathway was found to be interrupted because cholestanol is converted to 6-oxocholestanol, but further metabolism to 28-norcathasterone was not observed. The 6-oxoBRs were found to have been produced from the respective 6-deoxoBRs administered to the enzyme solution, thus indicating that these 6-oxoBRs are supplied from the late C-6 oxidation pathway. Heterologously expressed CYP85A1 and CYP85A2 in yeast catalysed this C-6 oxidation, with CYP85A2 being much more efficient than CYP85A1. Abnormal growth of <I>det2</I> and <I>dwf4</I> was restored via the application of 28-norcastasterone and closer precursors. Furthermore, <I>det2</I> and <I>dwf4</I> could not convert cholesterol to cholestanol and cholestanol to 6-deoxo-28-norcathasterone, respectively. It is, therefore, most likely that the same enzyme system is operant in the synthesis of both 28-norcastasterone and castasterone. In the presence of <I>S</I>-adenosyl-<SMALL>L</SMALL>-methionine, the cell-free enzyme extract catalysed the C-24 methylation of 28-norcastasterone to castasterone, although the conversion rates of 28-norteasterone to teasterone and 28-nortyphasterol to typhasterol were much lower; this suggests that 28-norcastasterone is the primary precursor for the generation of C<SUB>28</SUB>-BRs from C<SUB>27</SUB>-BRs.</P>
애기장대 내 새로운 브라시노스테로이드 결합체의 분리 및 동정
Se-Hwan Joo(주세환),Yew Lee(이유),Seong-Ki Kim(김성기) 한국생명과학회 2011 생명과학회지 Vol.21 No.5
애기장대에서 추출한 효소원에 동위원소로 표지 된 ³²P-ATP와 ³H-castasterone를 기질로 하여 효소반응을 수행하여 얻어진 생성물을 분석한 결과 ³H와 ³²P의 활성이 동시에 검출되었다. 이 대사산물의 구조를 알아보고자 동위원소로 표지 되지 않은 CS, ATP를 이용하여 효소 반응하여 얻어진 대사산물의 GC-MS 분석결과 ion m/z 664의 값을 얻었는데, 이를 CS phosphate로 예상할 수 있었다. 상기의 대사산물 분획에 wheat germ acid phosphatase를 처리하여 phosphoester 결합을 깨뜨린 후 얻어진 생성물의 GC-MS 분석결과 CS의 spectrum을 얻을 수 있었는데 이를 통해 식물체 내 CS의 결합체로 인산화 된 형태가 존재할 가능성을 확인하였다. Metabolism of ³H-castasterone in the presence of ³²P-ATP was examined by an enzyme solution prepared from A. thaliana after a reversed phased HPLC, after which a polar metabolite labeled by both ³H and ³²P was obtained, suggesting that ³H-CS is phosphorylated by ³²P-ATP. To elucidate the structure of the phosphorylated CS, the same enzyme assay was carried out with non-isotopes labeled CS and ATP. In GC-MS analysis the metabolite gave a molecular ion at m/z 664 as a bismethanboronate, suggesting the metabolite is a CS phosphate. Treatment of wheat germ acid phosphatase that hydrolyzed phosphoester bond gave the same mass spectrum and GC retention time in GC-MS analyses, confirming that the metabolite is phosphorylated CS. This is the first example of phosphorylated conjugates of CS in plants.