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임재규(Jae-Kyoo Lim),양승현(Seung Hyon Yang),국중하(Joong Ha Kook) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.8
The automobile is made up of thousands of parts. Some parts are formed by pressing and combined by spot welding. Among them, steel plate of fuel tank is formed in the metal mold and bending parts are jointed by spot and seam welding. To find weldability lobe of spot welding, clearance between two welding specimens was made and after spot welding, weldability is evaluated by means of tensile shear load, nugget size and shape. Specimen used in this study was a mild steel of 1.2mm thickness and electrode was Cu-Cr alloy of 6mm diameter. When spot welding started, the clearance of two specimens was changed 0mm, 3mm and 5mm step by step. The fractured surface of specimen after this test was observed Optical Microscope to measure microstructure and nugget shape. When clearance of two specimen was 3mm and 5mm, strength and nugget size was decreased and nugget shape was not clear.
직류전위차법을 이용한 AISI 316강 시효재의 탄소성 파괴인성 평가
임재규,장진상,Lim, Jae-Kyoo,Chang, Jin-Sang,Lino, Y. 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.3
AISI 316 steel has been used extensively for heater and boiler tube of the structural plants such as power, chemical and petroleum plants under severe operating conditions. Usually, material degradation due to microcrack or precipitation of carbides and segregation of impurity elements, is occured by damage accumulated for long-term service at high temperature in this material. In this study, the effect of aging time on fracture toughness was investigated to evaluate the measurement of material degradation. The elastic-plastic fracture toughness behaviour of AISI 316 steel pipe aged at $550^{\circ}C$for 1h-10000h (the aged material) was characterized using the single specimen J-R curve technique and eletric potential drop method at normal loading rate(load-line displacement speed of 0.2mm/min) in room temperature and air environment. The fracture toughness data from above experiments is compared with the $J_{in}$ obtained from predicted values of crack initiation point using potential drop method.
임재규,송준희,Lim, Jae-Kyoo,Song, Jun-Hee 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.10
The development of a new material which should be continuously use under severe environment of very high temperature has been urgently requested. For the development of such super-heat resistant materials, the main problem is not only to make the superior thermal barrier properties but also to actively release thermal stress. So, a new concept of functionally graded material(FGM) has been proposed to overcome this problem. A composition and microstructure of FGM are varied continuously from place to place in ways designed to provide it with the maximum function of mitigating the induced thermal stress. So, FGM can be applied in the aerospace, the electronic and the medical field, etc.. In this study, thermal stress analysis of sintering PSZ/NiCrAlY graded material was conducted theoretically using a finite-element program. The temperature condition was sintering temperature assuming a cooling-down process up to room temperature. Fracture damage mechanism was anlayzed by the parameters of residual stress. It could be known that FGM provided with the function of mitigating the induced thermal stress.
임재규(Jae Kyoo Lim),이상용(Sang Yong Lee),송준희(Jun Hee Song),최준용(Jun Yong Choi),김효진(Hyo Jin Kim),김연직(Yon Jig Kim),국중하(Jung Wha Guk),허남준(Nam Jun Heo) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.10
In recent years there has been a growing interest for the use of natural fibers in composite applications due to their low cost, environmental friendliness, and good mechanical properties. The purpose of this study is to determine the characteristic of bending strength on bamboo fiber reinforced polymer composites. The parameters of RTM process depend on the weight ratio of bamboo fiber and resin, the number of bamboo ply and amount of hardening agent. Besides the existence of pore in composites according to vacuum time investigated a effect on mechanical properties of reinforced polymer composites. Test result shows that bending strength was a maximum(approximately 850kgf/㎠) value when composite thickness was 6mm and weight ratio of resin was 13%.
변형속도를 고려한 Al/PC 접착제 접합부의 강도평가에 관한 연구
임재규(Jae-Kyoo Lim),윤호철(Ho-Cheol Yoon),유성철(Sung-Chol Yoo),서도원(Do-Won Seo),전양배(Yang-Bae Jeon) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.8
Adhesive bond joints are available for structural applications as understanding of adhesive bonding which has been improved. After adhesive materials are decided, the design of adhesive bonding joints is mainly focused on shape, dimension and surface treatment of joints. ill the design of single-lap joints lap length, thickness of adherend materials and surface treatment should be decided, these parameters have an main influence on strength of adhesive bonding joints. This study explains that surface treatment affects strength of Al/Polymer single-lap joints and loading speed affects adhesive strength design.
임재규,송준희,김연직,Lim, Jae-Kyoo,Song, Jun-Hee,Kim, You-Jig 대한기계학회 1998 大韓機械學會論文集A Vol.22 No.1
The development of a new material which should be continuously usable under severe environment of very high temperature has been urgently requested. The conventional thermal barrier coating(TBC) is a two layer coating, but a composition and a microstructure of functionally graded material(FGM) are varied continuously from place to place in ways designed to provide it with the maximum function of mitigating the induced thermal stress. The purpose of this study is to evaluate the heat-resistant characteristics by thermal shock of laser and furnace heating. The fracture behaviors of non-FGM(NFGM) and FGM were investigated based on acoustic emission(AE) technique during thermal shock test. Therefore, it can be concluded that FGM gives higher thermal resistance compared to NFGM by AE signal and fracture surface analysis.