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서유원,정성균,신용승 서울産業大學校 1997 논문집 Vol.46 No.1
The fundamental way in which fiber reinforced composites differ from conventional engineering materials such as metals is that the material properties are highly directional. This anisotropy affects the way in which the materials are used and the way in which the directions of the individual plies are selected. The stiffness properties needed for a plane-stress analysis are the modulus in the fiber direction E11, the modulus transverse to the fiber direction E22, the in-plane shear modulus G12, and one of the in-plane Poisson ratios ν12 and ν21. These properties are routinely characterized by laboratory experiments. Testing methods are examined to investigate mechanical characteristics of advanced composites, and basic properties are measured. Especially, the testing preparation, test processing, and results are examined in detail.
정성균,서유원 서울産業大學校 1999 논문집 Vol.49 No.2
In this paper, an artificially delamination in composite structures is detected by the ESPI system. And Chamber is made of acryl for laser to transmit. A specimen and a heat source are put into a chamber, which is sealed up to minimize heat convection. A specimen is heated up to about 5∼7℃ higher than room temperature. Cooling down the specimen, experimentation is accomplished by ESPI system. Experimental results show that the debond in a composite structure can be easily detected by ESPI. Moreover, it was shown that ESPI could be usefully applied to the detection of defects in various kinds of composite structures.
이승호,서유원,정성균 서울산업대학교 산업대학원 2000 大學院論文集 Vol.7 No.-
The surface treatment to increasing corrosion resistance is becoming influence as very important technology. The influence of shot peening on the corrosion resistance of SCM 420 steel is investigated in this work. Then, surface compressive residual stress and hardness considerably increased, which resulted in the increase of corrosion resistance.
결함을 갖는 기계부품의 표면가공에 따른 압축잔류응력의 영향 및 해석
이승호,서유원,정성균 서울산업대학교 산업대학원 2000 大學院論文集 Vol.7 No.-
Shot peening was applied on both smooth and notched specimen in order to investigate the stress distribution and the improvement in fatigue strength. The results shows that the fatigue strength of shot peened specimens increases by 34 percent compared to that of unpeened ones. Compressive residual stress also increased considerably, which resulted in the increase of fatigue strength. Finite element analysis showed that shot peening is effective in decreasing the bending stress by external force. the effectiveness of shot peening in reducing the compressive residual stress was anticipated by the superposition of the concentrated stress and the compressive residual stress.
신용승,이승호,서유원,정성교 서울産業大學校 1999 논문집 Vol.49 No.2
As developing the technology in industry, the materials with superior grade of stiffiness and lightness are required, and hence the higher fatigue strength characteristics are necessary. Thus, the non-traditional machining to increase fatigue strength is becoming influential as very important technology. Considering environmental problem, the shot peening process is selected as a good process to increase fatigue strength. But the data related to shot peening process are not enough in this country. Shot peening process is essential to ensure repeatability and uniformity on a part to part and lot to lot basis, while conforming to the applicable specifications. The shot material, size, shape and hardness as well as velocity and impact angle must be controlled to provide consistency in peening results. In order to effectively control the shot peening process, parameters must be addressed in the following order, such as media control, coverage control, intensity control, equipment control and so on.
김지은,김유진,서성준,홍창권 중앙대학교 의과대학 의과학연구소 2003 中央醫大誌 Vol.28 No.2-3
Mondor's disease is a rare disorder characterized by superficial thrombophlebitis and usually develop in thoracoabdominal wall. It has clinical feature of sudden development of painful cordlike structure. The cause is not determined in about 50-60% but it is suggested that trauma, surgery, exercise, drug abuse are often associated. A 44-year-old woman presented cordlike linear tender lesion on right thoracoabdominal wall and histopathologic examination revealed thrombophlebitis with organized thrombus.
김보영,박용규,박형서,노상필,정승현,이유선,이정우,이재환,최시완,정진옥,성인환 충남대학교 의과대학 의학연구소 2003 충남의대잡지 Vol.30 No.1
Atherosclerosis is now viewed as an inflammatory disease of the vascular system. Expression of several chemokines, including monocyte chemoattractant protein(MCP)-1, MCP-4, RANTES(regulated on activation normal T-cell expressed and secreted), and interleukin-8(IL-8) are increased in human atherosclerotic plaques compared with normal vessels. They are involved in the pathogenesis of atherosclerosis and plaque rupture by activating and directing leukocytes into the atherosclerotic lesions. However, some are involved in homeostatic functions such as normal leukocyte traffic and growth regulation. SDF-la is a multi-functional cytokine that is involved in myelogenesis, hematopoiesis, angiogenesis and injured gastric mucosal regeneration in the gastric ulcer patient. SDF-la is recently shown to be highly expressed in atherosclerotic plaques and a potent platelet agonist. At least in high concentrations, SDF-la may mediate antiinflammatory and matrix stabilizing effects in unstable angina. Many studies are going on to know the function of SDF-la in coronary artery diseases. I investigated the difference of the plasma level of SDF-la between control group and coronary artery disease group. Total 75 subjects were enrolled. The diagnosis of coronary artery disease was confirmed in all patients by coronary angiography. Control subjects in this study were confirmed normal by coronary angiography. Clinical profile and risk factors were also reviewed. Control subjects in this study were 27 (M=10, F=17). Plasma for the study was collected before the angiography and centrifuged. SDF-la analysis was performed by ELISA. Plasma level of SDF-la is significantly increased in patients with stable angina(n=20) and unstable angina group(n=28) compared with healthy control group(n=27). the risk factors do not influence the plasma level of SDF-la in coronary artery diseases. In this study, plasma level of SDF-la is increased in patients with stable angina and unstable angina groups compared with healthy control group(P<0.05). the risk factors do not influence the plasma level of SDF-la in coronary artery diseases.
Seo, Gimoon,Kim, Seong Keun,Byun, Yu Jeong,Oh, Eunhye,Jeong, Seong-Whan,Chae, Gue Tae,Lee, Seong-Beom Informa Healthcare 2011 Free radical research Vol.45 No.4
<P>A novel mechanism for H<SUB>2</SUB>O<SUB>2</SUB>-induced autophagic cell death in GSH-depleted RAW 264.7 cells, a murine macrophage cell line, is proposed. Under GSH-depleted conditions, H<SUB>2</SUB>O<SUB>2</SUB>-induced autophagic cell, characterized by an increased LC3-II/I ratio, a decreased level of p62 and the formation of autophagic vacuoles, was inhibited by bafilomycin A1 and by <I>Atg5</I> siRNA transfection, whereas the cell death was not inhibited by zVAD-fmk, by PI3K inhibitors or by <I>Beclin 1</I> siRNA transfection. In addition, H<SUB>2</SUB>O<SUB>2</SUB> treatment reduced the activity of mTOR and promoted the ubiquitination and degradation of Rheb, a key upstream activator of mTOR. Furthermore, proteasome inhibition with MG132 restored the expression of Rheb and increased mTOR activity, resulting in an increased viability of H<SUB>2</SUB>O<SUB>2</SUB>-treated cells. Collectively, these findings demonstrate that H<SUB>2</SUB>O<SUB>2</SUB> induces Beclin 1-independent autophagic cell death by suppressing the mTOR pathway via promoting the ubiquitination and degradation of Rheb in GSH-depleted RAW 264.7 cells.</P>