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조정 선수의 로잉 에르고미터 수행 후 저온침수 처치가 혈중 피로 물질, 활성산소 및 항산화 효소에 미치는 영향
홍현욱,고수한,김태규,김민교,김도연 한국응용과학기술학회 2023 한국응용과학기술학회지 Vol.40 No.4
The purpose of this study is to help a recovery of fatigue through the effect of cold immersion treatment after rowing ergometer on blood fatigue substance, MDA and SOD in rowing athletes. For this, 10 subjects participated in this study and we divided them into cold water immersion group (CWI, n=10), non-cold immersion group (NCI, n=10). The exercise program was performed to 2000 m rowing ergometer for maintaining high intensity. The data was collected with regard to the interaction effect of the group and time among the CWI and NCI, ANOVA was used. As the post-hoc test, Bonferroni test was used. The significance was set at .05 and the following conclusions were deduced. For lactic acid, there were the main effect of time (p<.001) and significant difference in the both group (p<.001). Also, LDH were significant difference in the each group (p<.05). For MDA, there were the interaction between group and time (p<.05) and the main effect of group (p<.05) and time (p<.001). SOD were indicated main effect of group and time (p<.05), there was significant difference between each group in the after 30 min recovery (p<.05). Collectively, The results of this study suggest that positive effect on blood fatigue substances, reactive oxygen species and anti-oxidation enzyme through cold water immersion intervention. Therefore, we strongly recommend that performing the cold immersion intervention would be beneficial after high intervention exercise.
입계 cavitation 손상기구에 기초하는 오스테나이트계 스테인리스강의 크리프-피로 수명예측법과 입계 탄화물 특성 변화에 의한 수명 향상에 관한 연구
洪鉉郁,南壽祐,尹暎喆,洪鎭完 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.4
It is understood that grain boundary cavitation is one of the detrimental processes for the degradation of austenitic stainless steels that reduces the creep-fatigue life at high temperatures. A new damage function based on a model for the creep-fatigue life prediction in terms of nucleation and growth of grain boundary cavities is proposed for austenitic stainless steel. This damage function is a combination of the fatigue and creep terms related to the cavitational damage (cavity nucleation and growth) in the life prediction equation and is found to be generally applicable to all the materials in which failure is controlled by the grain boundary cavitational damage. The cavity nucleation factor, P', which is introduced in the creep-fatigue life model, is found to be closely related with the characteristics of grain boundary carbides acting as cavity nucleation sites. The modification of carbide characteristics through grain boundary serration is successfully made by the special heat treatment so that the modified carbides are favorable for cavitation resistance, resulting in a lowered P' value of material. It is observed that the creep-fatigue life is remarkably improved by the modification of carbide characteristics through grain boundary serration.
니켈기 초내열합금의 파형 결정립계 구조가 보론 편석과 재현 열영향부 액화균열거동에 미치는 영향
홍현욱,최준우,배상현,윤중근,김인수,최백규,김동진,조창용,Hong, Hyun-Uk,Choi, June-Woo,Bae, Sang-Hyun,Yoon, Joong-Geun,Kim, In-Soo,Choi, Baig-Gyu,Kim, Dong-Jin,Jo, Chang-Yong 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.3
The transition of serrated grain boundary and its effect on liquation behavior in the simulated weld heat-affected zone (HAZ) have been investigated in a wrought Ni-based superalloy Alloy 263. Recently, the present authors have found that grain boundary serration occurs in the absence of adjacent coarse ${\gamma}^{\prime}$ particles or $M_{23}C_6$ carbides when a specimen is direct-aged with a combination of slow cooling from solution treatment temperature to aging temperature. The present study was initiated to determine the interdependence of the serration and HAZ property with a consideration of this serration as a potential for the use of a hot-cracking resistant microstructure. A crystallographic study indicated that the serration led to a change in grain boundary character as special boundary with a lower interfacial energy as those terminated by low-index {111} boundary planes. It was found that the serrated grain boundaries are highly resistant to boron enrichment, and suppress effectively grain coarsening in HAZ. Furthermore, the serrated grain boundaries showed a higher resistance to susceptibility of liquation cracking. These results was discussed in terms of a significant decrease in interfacial energy of grain boundary by the serration.