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순수 Ti 용접재의 기계적 특성 및 피로크랙 성장특성에 관한 연구
최병희,이종범,정장만,장경천,최병기 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.2
In this study, fatigue fracture often occurs due to the fatigue crack in the machine and welding structure and this is the result of severe operational environment, operational condition, and design condition caused by the large scaled and light weighted machine and structure in recent days. Therefore, safety and reliability should be secured to prevent the fatigue fracture of machine and structure, and the use of titanium has been increased in the metal material for the safety and reliability. The purpose of this thesis was to investigate the welding characteristics and fatigue crack growth characteristics of titanium, commonly using power station, aircraft and ship. The experimented material was TIG welded in order to look over the characteristics according to the notch position and compare with other material. The results, at the same welding condition, 4 pass specimen which had the smallest number of welding pass had the highest tensile strength with 51kgf/㎟ and the tensile strength of 4 pass specimen was 10% higher than the one of 7 pass specimen, and its elongation reduced about 30%. The initial fatigue crack growth characteristic is slower in this order, boundary zone < welding zone < HAZ < base metal. Especially boundary zone's growth speed is slower about 30 times than base metals.
최병희,이종범,정장만,장경천,최병기 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.2
In this study is about the fatigue characteristics which appears in the welding residual stress field. The welding residual stress takes place mostly at the portion where SS400 materials are automatical welded. The effects of the welding residual stress in the growth and propagation of fatigue crack, so as to study the fatigue behavior in the welding residual stress field. The results, in case of the load range is constant, as the stress ratio is changing to 0.1, 0.33. 0.5 the propagation life is constant but the growth life decreases. And than, when maximum load or minimum load is constant, as the stress ratio increases the growth life and propagation life increase. The fatigue crack propagations rate da/dN appears to accelerate when the stress intensity factor range △K is less than 15MPa-m^(1/2). The growing and propagation fatigue crack in the welding residual stress field is similar to original specimen after being passed the original residual stress field.
Proteomic Analysis of Resting and Activated Human CD8(+) T Cells
( Jung Hui Koo ),( Wook Jin Chae ),( Je Min Choi ),( Hyung Wook Nam ),( Tomohiro Morio ),( Yu Sam Kim ),( Yang Soo Jang ),( Kwan Yong Choi ),( Jung Jin Yang ),( Sang Kyou Lee ) 한국미생물생명공학회 2006 Journal of microbiology and biotechnology Vol.16 No.6