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Spray Forming 으로 제조된 고속도공구강에서 열간 단조에 따른 탄화물 분포 및 인성의 변화
안상호,이언식,이우진 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.7
ASP30 high speed steel billets showing different carbide microstructures of M₂C carbide cell and M_6C carbide cell have been prepared by the spray forming process. The variations of carbide distribution and bend fracture properties after hot forging have been investigated. Direct hot forging of spray formed materials has resulted in the formation of carbide clusters along hot working direction and bend fracture properties have been deteriorated. On the other hand, the metastable M₂C carbide has been completely decomposed to MC and M_6C carbides after high temperature exposure. The carbides are more uniformly distributed after forging and the bend properties increase significantly with decomposition treatment. The formation of M₂C carbide during solidification is preferable for obtaining a fine homogeneous carbide distribution after decomposition treatment and hot forging. The bend fracture properties of the spray formed ASP30 alloy have been found to be comparable to those of ASP30 alloy fabricated by powder metallurgy.
안상호,이강희,장성호,안면환,최창열,박승한 대한스포츠의학회 1999 대한스포츠의학회지 Vol.17 No.2
Objective : To compare isokinetic trunk muscle strength and endurance between control and elite athletes groups(wrestlers, baseball players, judo players, ssireum players) and among athletes, to come up with a trunk strengthening program for poorly trained athletes. Method : We have conducted out study using a CYBEX 7000 Trunk Extension Flexion(TEF) unit (Lumex, inc., Reonkonkoma, NY, U.S.A) to measure peak toruque per body weight trunk flexor and extensor, endurance and conentric flexor/extensor ratio. Results : The trunk flexor peak torque per body weight of the athletes groups excepte baseball players was significantly higher than that of the control group at nearly all the angle velocities (p<0.05). The trunk flexor peak torque per body weight of wrestlers was significantly higher than that of baseball, ssireum and judo players. The trunk extensor peak torque per body weight of wrestlers was significantly higher than that of the control group(p<0.05) and ssireum players. The trunk extensor peak torque per body weight of judo players was significantly higher than that of control group at rapid velocities(p<0.05). Conclusion : To strengthen trunk muscle in poorly trained athletes, sports-specific trunk muscle strengthening exercise may be helpful.