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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.
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.
Small biopsy from area of Hutchinson’s sign : useful for the diagnosis of subungual melanoma in situ
( Se Jin Oh ),( Young Hwan Choi ),( Hyun Jeong Byun ),( Seung Hwan Oh ),( Se-won Park ),( Ji-hye Park ),( Jong Hee Lee ),( Joo-heung Lee ),( Jun-mo Yang ),( Dong-youn Lee ) 대한피부과학회 2018 대한피부과학회 학술발표대회집 Vol.70 No.2
Background: Although nail matrix biopsy is recommended to diagnose subungual melanoma (SUM), it is technically demanding and has potential for complication including permanent nail dystrophy. Small biopsy from area of Hutchinson’s sign (HS), an important clinical clue for the diagnosis of SUM, is thought to provide adequate samples and less invasive than nail matrix biopsy. Objectives: We investigated the diagnostic value of small biopsy of HS in SUM in situ patients. Methods: We retrospectively evaluated 9 patients who were diagnosed as SUM in situ and underwent punch biopsy at HS area. Clinical features as well as histopathological findings at HS area were analyzed. Results: All patients had finger lesions and the most common area was the thumb (40%). HS was mostly seen in the hyponychium (90%), and only one case was seen in the proximal nail fold (10%). Histopathologically, all cases showed irregularly scattered atypical melanocytes. The size of the nucleus varied from small to large, and Focal pagetoid spread was observed in 6 cases. A confluent pattern of atypical melanocytes was observed in 4 cases. Three dermatologists reviewed the slides, and 8 out of 10 cases had no difficulty in diagnosing melanoma. The remaining two cases showed subtle changes which were not sufficient for the diagnosis for SUM in situ. Conclusion: When approaching longitudinal melanonychia, we suggest that small biopsy at HS area is less invasive and useful procedure that can be selectively performed first.