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서병욱(Seo Byung-Wook),함영삼(Ham Young-Sam),홍재성(Hong Jai-Sung) 한국철도학회 2004 한국철도학회 학술발표대회논문집 Vol.- No.-
In this paper, we would like to explain about the structure analysis of wheel set as variation of contact position between wheel and rail. Measurement of interacted force between wheel and rail is necessary for running safety evaluation as important factor of derailment mechanism. It"s necessary to running safety evaluation of rolling stock. Wheel unload and lateral force change as variation of contact position between wheel and rail. Interacted force between wheel and rail got as each contact position through computer simulation. This is necessary process as first research for evaluation of derailment phenomenon and running safety.
인간 피부섬유아세포에서 자외선 B 조사에 대한 Epigallocatechin Gallate 의 영향
서병욱(Byung Wook Seo),서성일(Sung Il Suh),백원기(Won Ki Baek),서민호(Min Ho Suh),김상표(Sang Pyo Kim),정태영(Tae young Jung),조재위(Jae We Cho),김병천(Byung Chun Kim),이규석(Kyu Suk Lee),류영욱(Young Wook Ryoo) 대한피부과학회 2001 대한피부과학회지 Vol.39 No.5
N/A Background : The main polyphenol components in green tee are (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate and (-)-epigallocatechin gallate (EGCG). It is well known that flavonoids such as catechins can be protective against inflammatory and cancer and cardiovascular diseases. These protective effects are largely due to their inhibition of some enzymes and antioxidative activities by scavenging free radicals. Ultraviolet(UV) exposure of the skin, particulary UVB (290-320nm), causes adverse biological effects, including alterations in cutaneous immune cells, photoaging and photocarcinogenesis. Several studies have shown that EGCG afforded protection against UVB-induced inflammatory responses and photocarcinogenesis in murine models. Objective & Methods : In this study, we investigated the effects of EGCG on UVB irradiated human skin fibroblasts using viability test, thiobarbituric acid assay, propidium iodide(PI) stain, and western blot analyses and RT-PCR. Results : Cell survival curves after UVB irradiation showed dose dependent decrement pattern by trypan blue exclusion assay. Only 42% of dermal fibroblasts survived at 150 mJ/cm2 UVB irradiation. The damage was associated with cell membrane lipid peroxidation, as shown by accumulation malondialdehyde(MDA). By pre-cultivation with EGCG (50nmol), a significant preventive effect was noted on the increase in the absolute number of surviving cells(up to 81.5% of cells survived) and the levels of MDA markedly decreased, Morphological changes associated with apoptotic cell death were easily distinguished by PI stain. Bases on our finding, we investgated the regulation of p53, p21, bax, bc1-2, cyclin Dl, E, Cdk2, and PARP proteins by western blot analyses. The expression p53 protein was elevated by following UVB exposure which was inhibited by EGCG treatment. Using RT-PCR, the transcription of p53, fas and jun gene showed similar results which obtained by western blot analyses. Conclusion : EGCG, which have newly accepted as a potential UV protection properties, is effective membrane peroxidation inhibitor and prevent apoptotic changes when present in relevant concentration at the site of action beginning and during UVB irradiation. And the protective mechanism of EGCG against UVB-induced cell damage maybe, at least in part, related with p53, fas and jun pathway.
함영삼(Ham Young-Sam),홍재성(Hong Jai-Sung),이관섭(Lee Kwan-Sup),서병욱(Seo Byung-Wook) 한국철도학회 2004 한국철도학회 학술발표대회논문집 Vol.- No.-
Safety from derailment has been evaluated according to the magnitude of the derailment coefficient, which does not always ensure sufficient safety evaluation, and is not necessarily helpful in clarifying the mechanism of derailment. When wheel rolls, point of contact between wheel and rail was change continuously and flange touches with rail. Established gauge so that can measure location of contact point between wheel and rail by strain gauge. Also, wish to describe result that compose bridge circuit and execute load test.