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김대영(Dae Young Kim),김정민(Jung Min Kim),김헌영(Heon Young Kim),송종호(Jong Ho Song),김관회(Koan Hoi Kim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
The welding point has been represented by rigid body element or link element in finite element analysis and simple failure criteria have been used for failure after large deformation. However, since the failure model of link element is removed at the highest loading point, it cannot support the load after the failure of welding point. Since this affects the energy absorbing characteristics of whole model in structural deformation, it became the main reason for the problem of analysis. Therefore, this paper simulated the failure characteristics of base metal of welding part by applying the EWK failure model and tried to predict the energy absorbing characteristics of base metal after failure, and verified by comparing the test and analysis. In order to express the behavior and failure of material, tensile tests and EWK tests(R notch type, U notch type, R parameter type) were performed. Also, we tried to predict the occurrence of tearing of base metal and load characteristics considering the welding part by comparing with the test result applying the EWK failure model for typical welding specimens(cross type, T type, Ⅰ type).
Stamping Analyses and Die Design of Laser Welded Automotive Body
Kim, Heon Young,Shin, Yong Seung,Kim, Koan Hoi,Cho, Won Seok 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.4
Computer simulations and test trials are carried out to get the optimal conditions of the design for the stamping of the laser tailor welded automotive body panels. Through test trials with new manufactured die for Tailor Welded Blanks (TWB), the effects of the initial position of blank, blank holding force, drawbead shape, and corner radius are investigated. The results of computer simulations show good correspondence with those of test trials. The results are directly applied to the modification of the die or changing of the forming conditions, to obtain well controlled sound product free from fracture, wrinkling or excessive weld line movement.
Cellular Signaling Molecules Associated with Peptidoglycan-Induced CCL3 Up-Regulation
( Kang Seung Kim ),( Byung Yong Rhim ),( Seong Kug Eo ),( Koan Hoi Kim ) 한국응용약물학회 2011 Biomolecules & Therapeutics(구 응용약물학회지) Vol.19 No.3
Peptidoglycan (PGN) is detected in inflammatory cell-rich regions of human atheromatous plaques. The present study investigated the effects of PGN on CC chemokine ligand 3 (CCL3) expression, which is elevated in the atherosclerotic arteries, and determined cellular factors involved in PGN-mediated CCL3 up-regulation in mononuclear cells, with the goal of understanding the molecular mechanisms of inflammatory responses to bacterial pathogen-associated molecular patterns in diseased arteries. Exposure of human monocytic leukemia THP-1 cells to PGN resulted in enhanced secretion of CCL3 and profound induction of the CCL3 gene transcript. Both events were abrogated by oxidized 1-palmitoyl-2-arachidonosyl-sn-phosphatidylcholine, an inhibitor of Toll-like receptors 2/4. Pharmacological inhibitors such as U0126, SP6001250, Akt inhibitor IV, rapamycin, RO318220, diphenyleneiodonium chloride, and N-acetylcysteine also significantly attenuated PGN-mediated CCL3 up-regulation. However, polymyxin B, LY294002, and SB202190 did not influence CCL3 expression. We propose that PGN contributes to enhanced CCL3 expression in atherosclerotic plaques and that Toll-like receptors (TLR2), Akt, mTOR, mitogen-activated protein kinase, and reactive oxygen species are involved in that process.
Biological Activity of Tumor Necrosis Factor-α Secreted from Smooth Muscle Cell Overexpressing FADD
김선미,이경아,김관회,Kim, Sun-Mi,Lee, Kyeong-Ah,Kim, Koan-Hoi Korean Society of Life Science 2007 생명과학회지 Vol.17 No.1
세포 배양액에 tetracycline이 없는 경우 FADD를 발현하면서 사멸하는 평활근세포 (FADD-SMC)에서 분비하는 $TNF-\alpha$의 활성을 조사하였다. 배양액에 tetracycline이 없는 경우 FADD-SMC는 약 1000 pg/ml의 $TNF-\alpha$를 분비하였다. $TNF-\alpha$를 포함하는 배양액을 분리하고, 이 배양액을 정상세포에 처리한 결과 인산화한 p38 MAPK와 nuclear, factor, kappa B (NF-kB)의 활성이 증가하였다. 또한 이 배양액을 L929 세포에 처리하는 경우 세포독성이 발생하였다. NF-kB, p38 MAPK 그리고 L929 세포에 대찬 효과는 배양액에서 suluble TNF receptor를 이용하여 $TNF-\alpha$를 제거하는 경우 감소하였다. This study investigated biological activity of tumor necrosis factor $(TNF)-\alpha$ secreted from smooth muscle cell (SMC) destined for death by expressing Fas associated death domain containing protein (FADD) (FADD-SMC) when the cells are grown without tetracycline in culture medium. In the absence of tetracycline the FADD-SMC secreted approximately 1000 pg/ml $TNF-\alpha$, whereas hardly detectable amount of the cytokine existed in the presence of tetracycline. The culture medium collected from the FADD-SMC grown in the absence of tetracycline increased phosphorylated form of p38 MAPK and up-regulated nuclear factor kappa B (NF-kB). The medium collected without tetracycline also caused death of L929 cells. Depletion of $TNF-\alpha$ with the soluble TNF receptor (sTNFR) inhibited the phosphorylation of p38 MAPK, the up-regulation of NF-kB activity and the death activity of the medium collected from FADD-SMC in the absence of tetracycline. These results indicate that $TNF-\alpha$ secreted from SMC undergoing death is biologically active and can affect cellular function.
Effect of Pyridoxine on Rifampicin Toxicity
Yun, Yeo-Pyo,Kim, Koan-Hoi,Kim, Hack-Seang,Chung, Jin-Ho The Pharmaceutical Society of Korea 1991 Archives of Pharmacal Research Vol.14 No.1
The effects of pyridoxine (PN) on rifampicin (RMF) toxicity were investigated by both in vivo and in vitro methods. RMF (30 mg/kg) was injected intraperitoneally and PN(150 mg/kg) was administered orally to rats for 10 consecutive days. After treatment, clinical chemistry and hematologic profiles were measured. RMF and PN plus RMF did not show any adverse effects at this in vivo experimental condition. Thymidine incorporations of mice bone marrow cells were examined in vitro. RMF showed a decrease in thymidine uptake in a dose-dependent manner, but PN showed a reversal of the thymidine uptake suppression caused by RMF (p<0.01). On the other hand, PN showed a decrease in thymidine uptake at a high concentration level.