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        유한요소법을 이용한 강-티타늄 이종소재의 폭발 용접조건 해석

        김청군,김명구,심상한,문정기,Kim, Chung-Kyun,Kim, Myung-Koo,Sim, Sang-Han,Moon, Jeong-Gi 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.3

        Using the two-dimensional hydrocode HI-DYNA2D, a calculation on the explosive selding of dissimilar plates(Steel Titanium) was made for the pressure, temperature, velocity and impact ingles adjacent to the collision point during the welding process. The FEM result indicates that optimal stand-off distance of initially parallel set-up is 3-5mm for various values of the explosive thickness. The calculation shows that when the explosive thickness is around 30mm, the temperature of welding point which is strongly related to the metallic jet formation is 2, 000-3, 500K for the given stand-off distance. 폭약의 폭발시 발생되는 초고압 충격 에너지를 이용한 강-티타늄 이종재질의 폭발접합 특성을 한요소기법에 의하여 실험적인 방법으로는 해석하기 어려운 미시적 관점의 접합조건을 해석하였다. 서로 다른 이종재질간의 접합에서 HI-DYNA2D 유한요소 코드를 이용한 계산결과에 의하면 충돌부근에서의 압력크기는 기존에 수행하였던 Oberg등의 수치적 해석결과와 잘 일치하고 있다. 한편, 폭약이 정상적인 폭발에너지를 발생시키기 위해서는 폭약이 30mm이상의 두께를 유지하여야 하며 50mm이상의 폭약두께는 폭접소재의 접합에 별다른 영향을 주지 못하고 있다. 즉, 폭약을 적게 사용하면 접합에너지가 부족하여 접합이 약하고, 폭약이 과도하게 많게되면 폭약의 손실이 많이 되므로 폭발용접 설계시 이들의 양을 미리 명확하게 예측하는 것이 대단히 중요함을 제시하였다. 한 평행한 상태에서 강-티타늄 이중소재를 접합할 경우의 이격거리는 3-5mm로 유지하는 것이 가장 양호한 접합상태를 얻을 수 있는 것으로 해석된다. 본 연구에서는 폭발용접의 접합특성 해석과 이에 강-티타늄 이종재질의 접합 설계조건을 실험적인 방법으로 구하지 않고, HI-DYNA2D 코드를 활용한 반복작업을 통하여 접합조건의 설계데이터를 충분히 얻을 수 있음을 확인하였다.

      • Experimental Study on Behavior Characteristics in Crankshaft Oil Seal

        Han Goo Kim(김한구),Sae-il Jeon(전세일),Myung Koo Kim(김명구),Akio Nakamura,Se Jong Yoo(유세종),Mun-Ha Lee(이문하),Myoung-Hun Oh(오명훈),Jung-Kyou Kim(김정규) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

        The behavior characteristics of the gasoline engine crankshaft oil seal regarding the assembling condition are being experimentally studied. Normally, most of the crankshaft oil seals are assembled onto the housing which is created after the cylinder block and the oil pan are assembled. Since the cylinder block and the oil pan are separate parts, mismatching quantity presence cannot be avoided which has influence on the crankshaft oil seal behavior characteristics. Thus, experimental study has been taken place for the leakage characteristic and the friction torque value change according to the mismatching amount variance and the engine oil temperature with the shaft velocities. The result shows that when the rotating shafts velocity is constant, leakage was present when it was over 0.6 ㎜ and friction torque increases proportional to the mismatching amount. From the experimental study, it was relevant that the assembling condition of the cylinder block and the oil pan has effects on the behavior characteristics for the crankshaft oil seal.

      • 만성 심부전환자의 혈액에서 측정한 Tumor necrosis factor-α 및 Interleukin-6의 임상적 의의

        김명구,김성구,박상호,한대희,강진환,변정득,심규혁,최병조,방덕원,온영근,현민수,권영주 순천향의학연구소 2001 Journal of Soonchunhyang Medical Science Vol.7 No.2

        Background and objectives: Many conditions are responsible for the pathophysiology and progressive mechanisms of congestive heart failure. More recently, it has also become evidence that another class of biologycally activated molecules generically reffered to as cytokine these are also over expressed in congestive heart failure. Therefore, the purpose of this study was to measure concentrations of tumor necrosis factor-α(TNF-α), interleukin-6(IL-6) in mild to severe symptoms of heart failure and compare their values with those found in normal control and analysed correlation relationship between cytokine level, clinical findings and hemodynamic indicies. Subjects and Methodology: Levels of TNF-α and IL-6 were measured on pulmonary artery during cardiac catheterization in heart failure patients(n=32) and normal subjects(n=8) as well as physical examination and echocardiogram. Cytokines assay were performed on plasma using commercially available ELISA(Enazyme-Linked Immunosorbent Assay) kits. Results: Although the levels of TNF-α and IL-6 tend to increase in congestive heart failure group, the cytokines level was not made significantly statistical difference between congestive heart failure group and controls. When analyzing the correlation between the levels of PCWP(pulmonary capillary wedge pressure) and cytokines(TNF-α, IL-6), respectively, there were statistically significant correlation coefficient 0.32,(p<0.05), 0.39(p<0.01). The cytokine IL-6 and pressure of pulmonary artery were significant correlation.(correlation coefficient 0.36, p<0.02) More significantly, there was correlated with TNF-α and IL-6.(correlation coefficient 0.57, p<0.001) Conclusions: There was tended toward high concentration of TNF-α & IL-6 in congestive heart failure and significant difference for PCWP between TNF-α & IL-6, thus may be correlated with development and progression in congestive heart failure.

      • 허혈성 심질환에서 염증지표에 관한 연구

        번정득,권영주,박상호,한대희,이상철,강진환,김명구,심규혁,최병조,온영근,현민수,김성구 순천향의학연구소 2001 Journal of Soonchunhyang Medical Science Vol.7 No.2

        Background : Atherosclerosis is the chief underlying cause of ischemic heart disease and there is increasing evidence that inflammation is an important determinant of the development of atherosclerosis. We assessed the levels of inflammatory markers in patients with ischemic heart disease and normal group who has normal coronary angiograms. Materials and Methods : Coronary angiography was performed in 142 patients. 107 patients of ischemic heart disease(stable angina pectoris 58, unstable angina pectoris 30, Acute myocardial infarction 19) and 38 normal control subjects. We assessed the level of inflammatory markers, such as CRP, ESR, fibrinogen and leukocyte. Results : CRP, ESR and fibrinogen values of the patients with stable angina pectoris and unstable angina pectoris were higher than that of normal control group, but there were no statistical significance. Leukocyte value of the patients with unstable angina pectoris(9003.3±701.5/mm^(3)) was significantly higher than that of the patients with stable angina pectoris(6685.5±245.8/mm^(3)) and normal control subjects(6394.3±235.1/mm^(3)). CRP, ESR and fibrinogen values of the patients with acute myocardial infarction were also higher than that of normal control subjects. CRP was 3.88±2.05 mg/dL in acute mocardial infarction group, and 0.29±0.15 mg/dL in normal control subject group(p<0.05). Fibrinogen was 541.6±45.1 mg/dL in acute myocardial infarction group, 321.4±25.6 mg/dL in normal control subject group(p<0.05). Leukocyte was 10942.1±737.6/mm^(3) in acute myocardial infarction group, 6394.3±235.1/mm^(3) in normal control subject group(p<0.05). Conclusions : This study demonstrate that CRP, fibrinogen and leukocyte values of acute myocardial infarction group were significantly higher than that of control group and stable, unstable argina pectoris group. Leucokyte values were significantly elevated in unstable angina group, but CRP values were not in unstable angina group.

      • 관상동맥질환 환자에서 스텐트 시술 후 재협착에 관한 연구

        강진환,권영주,박상호,한대희,이상철,김명구,변정득,최병조,심규혁,온영근,현민수,김성구 순천향의학연구소 2001 Journal of Soonchunhyang Medical Science Vol.7 No.2

        Background and aims : In the coronary artery disease, a rate of restenosis was much decreased by placement of coronary stent than when percutaneous transluminal coronary angioplasty has been applied, but there are still important clinical problems of restenosis. There has been many progressive studies about various factors contributed to this restenosis. So, we studied a relation between restenosis after placement of coronary stent in the coronary artery disease and many clinical factors, characteristics of stenotic lesion and procedural factors, and also assessed the restenosis rate of various coronary stents. Methods : Total 58 lesions(46 cases of patients ; man 30, woman 16) were evaluated, which has been performed a follow-up coronary angiography after 6 months (mean 188 days) since coronary stent had been placed. Various stents were implanted and assessed a relation between restenosis and many factors. Results : Of 58 lesions were target stenotic studies, there were 22 of restenotic lesions(37.9%), and the restenosis rate wes statistically significant difference in the relation with diabetes mellitus(p<0.05), group of acute myocardial infarction(p<0.05) among clinical diagnosis of ischemic heart disease(stable angina, unstable angina and acute myocardial infarction) in clinical factors and with high dilation pressure of stent(p<0.05) in procedural factors. When the rate of restenosis was evaluated among implanted stents, it was lowest in the Multilink^(®) stent and highest in the Nir Royal^(®) stent(60%). Conclusion : In this study of restenosis and various factors after placement of stents in the coronary artety disease, factors such as diabetes mellitus, group of acute myocardial infarction and a dilation pressure of stent were significant related with restenosis and the restenosis rate of Multilink^(®) stent was lowest and the highest restenosis rate was of Nir Royal^(®) stent.

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