http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
차강일(Gang il Cha),송성민(Seong min Song),조한서(Han seo Cho),전승호(Seung ho Jeon),김명규(Myung kyu Kim),유상석(Sang seok Yu) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
In PCB(printed circuit board) electrical test, failure phenomena are occurred such as pin slip and pad delamination. This phenomena result in damage of PCB and decrease of yield rate. Property analysis of pin-pad contact is needed to improve arrangement and degree of precision. In this study, high speed digital camera is used to capture the instance of pin contact on the pad. The lab scale jig is applied to the experiment of the observation. And to control of pin-pad movement, the three dimension moving system is developed using manual and motorized stages. The lens system is consist of 10x objective and 12x zoom lens to changing FOV(field of view). And the light system is composed 1㎾ halogen lamp and concave mirrors, to enhance light source. Using the system, the 70㎛ pin and 20㎛ pad contact scenes are acquired. And pin slip phenomenon is shown in pin-pad contact scenes.
권대일(Dae Il Kwon),정영기(Young Gi Jeong),조한샘(Han Saem Cho),박현남(Hyun Nam Park),김동열(Dong Yul Kim),박성수(Sung Soo Park),고한서(Han Seo Ko) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
A period of winter has shortened and a period of summer has lengthened in Korea because .the climate has become a subtropical climate lately, which is contrary to a temperate climate in past years. Furthermore, a discomfort index is getting higher in summer because of high humidity. Therefore, the use of an air conditioner has increased steadily and the electric usage in summer has highly risen annually. Since this situation is unavoidable to live in Korea, it is required to find efficient methods to develop the air conditioners. One of the methods which was attempted in this study was an improvement of the efficiency for a room air conditioner(RAC) by redesigning the outlet blade. The best design has been selected in this study by examining the change of mass flow rate and direction of the cold air for the improved efficiency after redesigning the outlet blade. A commercial software, FLUENT, has been used to analyze the phenomena. Finally, an existing model has been compared with the redesigned model to confirm the improved efficiency.
압입시험을 이용한 압력용기강 저인성 용접부의 취성파괴 천이특성 평가
홍준화,조한서,이봉상,양원존 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.9
Fracture toughness of the weldment of a pressure vessel steel was evaluated by ABI(automated ball indentation) tests in the transition temperature region. The evaluation procedure was based on the semi-empirical IEF(indentation energy to fracture) theory that has been recently developed using two basic assumptions. One is that the triaxial stress state beneath the ball indenter is similar to that of a crack tip ahead. Second, the fracture stress of a material is almost temperature-independent in case the stress-controlled cleavage fracture occurs. The fracture toughness characteristics determined by ABI tests were comparable to those obtained by standard 3-point bending tests. The multi-passed weldment was divided into two parts by their macroscopical appearances; as-solidified region and recrystallized one. However, both regions did not show a significant difference in fracture toughness as well as hardness and flow properties in the tested material.
Al-Zn-Mg-Mn 계 용접용 알루미늄합금과 Al 7039 의 여러 분위기에서의 저주기 피로성질에 관한 연구
남수우,조한서 대한금속재료학회(대한금속학회) 1994 대한금속·재료학회지 Vol.32 No.7
The strain controlled low-cycle fatigue properties of recently developed weldable Al-Zn-Mg-Mn alloy and commercial Al 7039 alloy were studied in air, distilled water and 3.5wt.% NaCl solution. While the tensile strength of the Al-Zn-Mg-Mn is greater than that of 7039 alloy, the fatigue life of the Al-Zn-Mg-Mn alloy is found comparable to those of the Al 7039 alloy at the condition of the same total strain range in all the environments tested. However, the fatigue life of the Al-Zn-Mg-Mn alloy is appears longer than that of the Al 7039 in terms of the dissipated energy per cycle in the specimen. These results are considered to be caused by the difference in cyclic deformation behavior between the weldable Al-Zn-Mg-Mn alloy and Al 7039 alloy.
원소분말압출법으로 제조된 TiAl-계 합금의 크리프 성질
남수우,황선근,김낙준,조한서 대한금속재료학회(대한금속학회) 1996 대한금속·재료학회지 Vol.34 No.10
Creep properties of the lamellar structured Ti-46.6Al-1.4Mn-2Mo(at%) alloy, which is made by hot extrusion of a blended elemental powder mixture, are investigated in air environment over the temperature range from 1023K to 1173K at constant stress levels ranging from 100MPa to 250MPa. The average activation energy for creep within the temperature range from 1048K∼1173K at stress level 150MPa and 200MPa is found to tie 384kJ/㏖. The value of the stress exponent n in the range of 3.8∼4.3 was obtained within the stress range from 150MPa to 250MPa and 1.3 between 100MPa and 150MPa at 1073K. Microstructural studies conducted on creep fractured specimen showed the secondary cracks along the lamellar grain boundaries and the secondary cracks are assumed to be formed by pore nucleation, growth and coalescence during the tertiary stage.