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임문혁,김문석,김희중 啓明大學校 産業技術硏究所 1997 産業技術硏究所 論文報告集 Vol.20 No.-
It was well known that 70-80% of the fracture of steel plate was due to fatigue fracture. A fatigue behvaior of infinite steel plate was examined in this study. The stress concentration phenomenon around the hole in the steel plate was an important factor for the fatigue fracture. The diameter of the holes existing in the steel plate were varied from 0.1mm up to 0.4mm, and the number of hole was 1 and 3 in this study. It was shown that the stress concentration was exponentially increased as the angle of the crack in the plate was decreased. The initial value of stress concentration was smoothly increased as the diameter of hole was when the hole existed in the steel plate logarithmically decreased as the angle of hole was decreased. As a result of this study, it was found that the fatigue strength decreased extreamly when the small hole occurred in the steel plate. Consequently, greate care for fatigue strength should be excercised in designing steel mumbers.
Fe-Ni-Co 저열팽창성 합금의 고온 변형 특성 및 열간가공에 따른 열팽창 거동 연구
이기안,박종혁,조봉현,남궁정,김문철 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.9
The high temperature deformation behavior and the effect of hot compression on the thermal expansion behavior of Fe-29Ni-17Co low thermal expansion Kovar alloy were investigated in the compressive temperature range of 900~1300℃ at the strain rate range of 25~0.01 sec.^(-1). The temperature (T) and strain rate (ε˙) dependence of the flow stress (σ_(0.7)) could be well described by hyperbolic sine law as ε˙= A [sinh(0.0084 σ)^(5.2018)] exp(-330.41/RT). Surface hot cracking and significant voids around grain boundary could be found at low temperature below 1000℃ and low strain rate (0.01 sec.^(-1)). Thermal expansion coefficient α_(30~400) generally increased with increasing compressive temperature. Moreover, α_(30~400) remarkably increased as strain rate decreased at high temperature above 1100℃. However the thermal expansion coefficient α_(30~400) of low compressive temperatures (900℃ and 1000℃) anomalously increased especially at high strain rates. Experimental results indicated that not only α phase appearance but also grain size had definite influence on the thermal expansion behavior with hot deformation. The correlation between microstructure and thermal expansion behavior of Kovar alloy were also discussed.
( Mun Hyuk Seong ),( Ho Kil ),( Jong Yeop Kim ),( Sang Soo Lee ),( Sook Hyang Jeong ),( Young Seok Kim ),( Si Hyun Bae ),( Youn Jae Lee ),( Han Chu Lee ),( Hae Sun Yun ),( Byung Hak Kang ),( Kisang Ki 대한간학회 2012 춘·추계 학술대회 (KASL) Vol.2012 No.-
Background: Hepatitis C virus (HCV) infection is attributable to about 15% of cause of chronic liver disease in Korea. We aimed to study the epidemiological and clinical features of a prospective, multicenter cohort of HCV infection in Korea. Methods: A total 1,173 adult patients showing positive results for anti-HCV were prospectively enrolled and offered to complete the questionnaire survey on the risk factors of HCV infection from January 2007 to December 2011 at 5 university hospitals. Predefined demographic, clinical, and virological variables were collected and analysed. Results: The 1,173 subjects of the HCV cohort showed that mean age of 55.4 years, and male proportion of 48.3%, and diagnostic category of acute hepatitis (n=64, 5.5%), past infection (n=54, 4.6%), chronic hepatitis (n=772, 65.8%), liver cirrhosis (n=183, 15.6%), and hepatocellular carcinoma (n=100, 8.5%). The HCV genotypes were distributed into 5 types: genotype 1 (n=489, 52.4%), genotype 2 (n=421, 45.1%, genotype 3 (n=7, 0.8%), genotype 4 (n=2, 0.2%), and genotype 6 (n=9, 1.0%) with mixed genotypes (n=5, 0.5%). Hepatitis B virus coinfection rate was 3.5%. Liver biopsy was undertaken in (n=298, 20.0%), and the antiviral therapy against HCV had been undertaken in 42.8%. The risk factors were found as below: blood transfusion before 1995 (55.9%), needle stick injury (7.4%), acupuncture (82.5%), tattooing (36.0%), piercing (35.0%), intravenous drug abuse (IVDU) (5.0%), multiple sex partners more than 3 (21.0%), living with HCV-infected person (2.6%). Interestingly, patients living in Busan area showed higher frequency of IVDU (10.3%) compared to those in Capital area (4.5%).
( Mun Hyuk Seong ),( Ho Kil ),( Jong Yeop Kim ),( Sang Soo Lee ),( Sook Hyang Jeong ),( Young Seok Kim ),( Si Hyun Bae ),( Youn Jae Lee ),( Han Chu Lee ),( Hae Sun Yun ),( Byung Hak Kang ),( Ki Sang K 대한간학회 2012 춘·추계 학술대회 (KASL) Vol.2012 No.1
Background: Hepatitis C virus (HCV) infection is attributable to about 15% of cause of chronic liver disease in Korea. We aimed to study the epidemiological and clinical features of a prospective, multicenter cohort of HCV infection in Korea. Methods: A total 1,173 adult patients showing positive results for anti-HCV were prospectively enrolled and offered to complete the questionnaire survey on the risk factors of HCV infection from January 2007 to December 2011 at 5 university hospitals. Predefined demographic, clinical, and virological variables were collected and analysed. Results: The 1,173 subjects of the HCV cohort showed that mean age of 55.4 years, and male proportion of 48.3%, and diagnostic category of acute hepatitis (n=64, 5.5%), past infection (n=54, 4.6%), chronic hepatitis (n=772, 65.8%), liver cirrhosis (n=183, 15.6%), and hepatocellular carcinoma (n=100, 8.5%). The HCV genotypes were distributed into 5 types: genotype 1 (n=489, 52.4%), genotype 2 (n=421, 45.1%, genotype 3 (n=7, 0.8%), genotype 4 (n=2, 0.2%), and genotype 6 (n=9, 1.0%) with mixed genotypes (n=5, 0.5%). Hepatitis B virus coinfection rate was 3.5%. Liver biopsy was undertaken in (n=298, 20.0%), and the antiviral therapy against HCV had been undertaken in 42.8%. The risk factors were found as below: blood transfusion before 1995 (55.9%), needle stick injury (7.4%), acupuncture (82.5%), tattooing (36.0%), piercing (35.0%), intravenous drug abuse (IVDU) (5.0%), multiple sex partners more than 3 (21.0%), living with HCV-infected person (2.6%). Interestingly, patients living in Busan area showed higher frequency of IVDU (10.3%) compared to those in Capital area (4.5%).
( Mun Hyuk Seong ),( Ho Kil ),( Jong Yeop Kim ),( Sang Soo Lee ),( Eun Sun Jang ),( Jin Wook Kim ),( Sook Hyang Jeong ),( Young Seok Kim ),( Si Hyun Bae ),( Youn Jae Lee ),( Han Chu Lee ),( Hae Sun Yu 대한간학회 2013 Clinical and Molecular Hepatology(대한간학회지) Vol.19 No.1
Background/Aims: The distribution of hepatitis C virus (HCV) genotypes varies geographically. In Korea, genotypes 1 and 2 comprise more than 90% of HCV infections, while genotype 6 is very rare. This study compared the clinical and epidemiological characteristics of patients with genotype 6 HCV infection with those infected with HCV genotypes 1 and 2. Methods: This was a prospective, multicenter HCV cohort study that enrolled 1,173 adult patients, of which 930 underwent HCV genotype analysis, and only 9 (1.0%) were found to be infected with genotype 6 HCV. The clinical and epidemiological parameters of the genotypes were compared. Results: The patients with genotype 6 HCV had a mean age of 41.5 years, 77.8% were male, and they had no distinct laboratory features. A sustained virologic response (SVR) was observed in four (67%) of six patients who received antiviral therapy. Risk factors such as the presence of a tattoo (n=6, 66.7%), more than three sexual partners (n=3, 33.3%), and injection drug use (n=3, 33.3%) were more common among genotype 6 patients than among genotypes 1 or 2. Conclusions: The epidemiology and treatment response of patients infected with genotype 6 HCV differed significantly from those with genotypes 1 or 2, warranting continuous monitoring. (Clin Mol Hepatol 2013;19:45-50)