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허용학(Yong-Hak Huh),R.E Edwards,M.W. Brown,E.R. de los Rios 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.3
Governing parameters on location of crack Initiation and direction of crack initiation were investigated by performing fretting fatigue tests and analysis on Al 2024-T351. Fatigue tests were carried out using biaxial fatigue machine. It was shown that the dominant fatigue crack tended to initiate at the outer edge of one of the four bridge pads, growing at an angle beneath a pad, before turing perpendicular to the orientation of the axial load. Distribution of stresses generated during fretting fatigue loading along the interface was calculated by elastic FE simulation. It can be known that the location of crack initiation can be predicted by using the maximum tangential stress range or the maximum shear stress range. Futhermore, the crack initiation direction can be predicted by a maximum tangential stress range.
허용학(Yong-Hak Huh),김동일(Dong-Iel Kim),한준희(Jun-Hee Hahn),김광석(Gwang-Seok Kim),연순창(Soon-Chang Yeon),김용협(Yong-Hyub Kim) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
Tensile properties of hard coating material, TiN, were evaluated using micro-tensile testing system. TiN has been known as a hard coating material commonly used today. Micro-tensile testing system consisted of a micro tensile loading system and a micro-ESPI(Electronic Speckle Pattern Interferometry) system. Micro-tensile loading system had a maximum load capacity of 500mN and a resolution of 4.5 ㎚ in stroke. TiN thin film 1㎛ thick was deposited on the Si wafer pre-deposited of Si₃N₄ film substrate by the closed field unbalanced magnetron sputtering (CFUBMS) process. Three kinds of micro-tensile specimen with the respective width of 50㎛, 100㎛ and 500㎛ were fabricated by MEMS process. The mechanical properties including tensile strength and elastic modulus were determined using the micro-tensile testing system and compared by those obtained by nano-indentation
이축 하중이 작용하는 구멍 주위에서 피로 균열 발생에 대한 위상차의 영향
허용학(Y.H. Huh),박휘립(P.Park),김동진(D.J. Kim),이완규(W.K. Lee) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
Effect of phase difference on fatigue crack initiation around a hole subjected to biaxial fatigue loads was investigated. Axial and torsional biaxial fatigue loads with different phase differences and biaxiality of 1/√3 were applied to thin-walled tubular specimens. Five phase differences of 0. 45, 90, 145 and 180 degrees were selected. Direction of the fatigue crack initiation around the hole was found to approach to the circumferential direction of the specimen with increment of the phase difference for<br/> fatigue tests with phase difference less than 90˚. Whereas the direction for tests with phase<br/> difference greater than 90˚ was symmetric to that for tests with phase difference less than 90˚. Furthermore, it was shown that the fatigue initiation life decreased with increment of phase difference but it increased for tests with phase difference greater than 90˚ . The crack initiation direction can be successfully explained by using the direction of the maximum tangential stress range obtained around the hole and at far-field.
허용학(Y.-H. Huh),김동일(D.I.Kim),김동진(D.J. Kim),이경호(K.Lee),김동진(D. Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Adhesion strength of single layer ceramic capacitor sheet was measured using a peel testing system developed in this study. The peel test specimens with various dimensions were prepared from the ceramic sheet cast on the PET film. In peel test, the sheet specimen was adhered on the glass jig floating on the liquid media, which was designed to minimize the friction, and the specimen was then pulled up by micro-actuator. During the separation of the sheet from the PET film, peel force was measured. To normalize the testing condition, 3 different widths of the specimen were selected: 5, 10 and 20 ㎜. was used Furthermore, testing speed effect was investigated in this study. From the resullts using various testing conditions, the standard method for the peel strength testing may be suggested. Based on the testing condition, effect of peel angle on the strength was experimentally examined. It was found that the adhesive strength for the ceramic sheet is nearly identical, irrespective of the specimen width ranged from 5 to 20 ㎜, while the adhesive strength was increased with increasing testing speed. Furthermore, the strength was shown to be dependent on the peel angle.
양성질환 및 악성종양에서 혈청 CA19 - 9 와 CEA 의 비교
허용진(Yong Jin Huh),장덕기(Duck Key Jang),이상팔(Sang Pal Lee),최재철(Jae Chul Choi),김호균(Ho Kyun Kim),서동룡(Dong Ryong Seo) 대한내과학회 1989 대한내과학회지 Vol.36 No.5
N/A To analyze the sensitivity and specificity of CA19-9 and carcinoembryonic antigen (CEA) in benign and malignant disease, we performed a study to measure the concentration of both tumor markers among the patients admitted in Maryknoll Hospital between October 1987 and October 1988. The results were as follows: 1) The concentrations of serum CA19-9 and CEA were significantly higher in malignant tumor than benign disease. 2) At a cutoff of CA19-9 37 U/ml and CEA 5 ng/ml, CA19-9 had higher sensitivity than CEA in stomach cancer, hepatocellular carcinoma, colon cancer, especially in pancreatic carcinoma and cholangiocarcinoma. 3) There were no significant differences in concentration of CA19-9 and CEA among the stages of stomach cancer. 4) Pancreatic carcinoma with hepatic metastasis had higher concentrations of CA19-9 and CEA than without hepatic metastasis. In conclusion, CA19-9 is not specific for certain malignant tumors, but is more sensitive than CEA in gastrointestinal cancers.
TRIZ/CAE를 활용한 철도차량 윤축용 캡의 창의적 설계
허용정(Huh, Yong-Jeong),김재민(Kim, Jae-Min),홍성도(Hong, Sung-Do) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.6
철도차량의 안전성을 위해 사용되는 윤축은 차량 전체 중량의 16% 를 차지하는 요소로서, 철도차량의 경량 화에 있어 필수적으로 연구되는 대상이다. 본 연구는 기존 윤축의 중량을 요구강도에 만족시킴과 경량화를 목적으로 창의적 문제해결이론인 TRIZ의 6SC를 적용하여 중공구조의 윤축 내부에 사용될 수 있는 캡을 설계하였고, 설계에 대한 검증을 위해 해석 툴인 ANSYS를 활용하였다. 본 연구에서 제안한 캡의 재질은 SM45C이며 중공구조이다. 또 한, 윤축에 요구되는 강도를 만족하기 위해 중공 윤축의 베어링 시트 부 내부에 위치한다. 본 연구를 통해 설계 및 해석된 캡을 삽입한 윤축은 전동차의 윤축에 요구되는 기준을 만족하였으며 무게는 중실축과 비교하였을 때, 약 6.76%를 감소시켰다. 윤축 강도에 대한 평가 기준은 EN13103 및 EN13104의 규격을 적용하였다. 또한, 캡을 장착한 윤축의 최대응력 및 중량에 대해 기존의 중실축, 중공축과 비교함으로써 설계에 대한 효과를 검증하였다. This paper aims at the design of wheel and axle with cap. The cap is conceptually designed by using TRIZ/CAE. Wheel axle is used at railway vehicle to safety and it is always investigated to reduce the railway vehicle weight. The cap has hollow shaft with the material of SM45C. Cap is located in the bearing seat of wheel and axle. The cap becomes durable within the allowable stress of EN13103, 13104 standard. In this study, the strength of wheel and axle with cap becomes higher than that of hollow shaft. The weight of wheel and axle with cap becomes lower by about 6.75 percent than that of solid shaft. The confidence of wheel and axle with cap can be improved by comparing with solid and hollow shafts.
LPG 충전소 저장탱크의 설치방법에 따른 경제성 분석에 관한 연구
허용정(Yong-Jeong Huh),임주연(Ju-Yeon Lim),염무열(Moo-Youl Youm),임사환(Sa-Hwan Leem) 한국가스학회 2016 한국가스학회지 Vol.20 No.1
환경 친화적 자동차는 우리나라 정부가 추구하는 저탄소 녹생 성장 전략의 상징이어 왔다. 최근 정책 추세에 맞추어, 새로운 LPG 충전소가 많이 지어지고 있다. 하지만 대규모 가스 저장시설에서의 안전사고는 사회적으로 막대한 인명 피해와 재산 피해를 야기시켜 왔다. 이 논문에서는, LPG 충전소에서 안전사고를 사전에 예방하기 위하여 설치방법에 따라 경제적 분석을 실시하였다. 분석결과, 지하 저장소는 그 유지관리 및 효율적인 토지이용 면에서 긍정적인 것으로 나타났다. Eco-friendly automobile has been a symbol of the Low Carbon, Green Growth strategy that Korea government decided to pursue. In line with the recent policy trend, a number of new LPG stations are being constructed. However, communities where mass storage are installed have been suffered from risk of serious accidents. In this work, economic analyses for different installation methods has been performed to prevent accidents in LPG filling station. The review shows that the underground storage is beneficial for the maintenance and the effective land use.