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Fracture Criterion for AZ31 Mg Alloy Plate at Elevated Temperature
석동윤,김대용,김상우,백정환,이영선,정관수 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.1
The fracture criterion was characterized for an AZ31 Mg alloy plate with the 3.0 mm thickness at the elevatedtemperature of 250 °C in this work. In order to properly characterize the fracture criterion, its mechanicalproperties were also characterized. As for mechanical properties, simple tension tests were performed tocalibrate the Hill1948 yield function. Also, in order to account for the hardening deterioration (softening)behavior beyond the uniform deformation limit, the flow curves of the Mg alloy plate were numericallyobtained based on the inverse calibration method, in which strain rate sensitivity was also considered. Asfor the fracture criterion, effective fracture strains, which are dependent on stress triaxiality and deformationpaths, were numerically characterized utilizing experimental data based on specimens with four differentshapes newly developed. For comparison purposes, empirical fracture criteria such as the Cockcroft-Latham,Brozzo, Ayada and Clift models were also calibrated. For validation purposes, the five fracture criteriawere applied for a real part (an EL-cover) drawing case and the result confirmed that the fracture criteriondeveloped in this work performed best among the five models tried out.
12 경락(經絡)의 속성(屬性)과 운동변화(運動變化)의 경향성(傾向性)을 파악(把握)하기 위한 연구(硏究)
석동윤,최찬헌,장경선,Shuk Dong-Yun,Choi Chan-Hun,Jang Kyeong-Seon 경락경혈학회 2000 대한침구의학회지 Vol.17 No.1
The purpose of this study is to understand the special character and the tendency of the movement change that 12 meridians possess. We studied about the incidental and fundamental rule of the six atmospheric influence that was presented by Pyobonjoong(the incidental, fundamental, intermediate) theory, and the Hwang won-uh's the Six Channel activity of the Qi theory that presented movement form of the meridian through the six atmospheric influence. Then we found the following substances. The Pyobonjoong(the incidental, fundamental, intermediate) theory is applicable to understand the special character and the tendency of the movement change that Meridians possess. But, because the Pyobonjoong(the incidental, fundamental, intermediate) theory can't classify the characteristic difference of the hand and foot meridians, then the principle that can devide the meridians of the hand and foot, must be supplied. The Jungwha(right changing)-Daewha(opposite changing) theory is able to concretely classify the special character of the hand and foot six meridians. And Hwang's Shawha(superintending change)-Jongwha(following change) theory that is base on Jungwha(right changing)-Daewha(opposite changing) theory, is able to classify the special character of the hand and foot six meridians, too. If the concept of the Meridians is understood by the Shawha(superintending change)-Jongwha(following change) theory, the special character of the hand and foot six meridians could be concretely classified and then the meridian of the Bowels and the six atmospheric influence corresponded to the meridians could be expansively explained as the point that take charge and control these special Qi in the human body The Bon-Qi(fundamental Qi) act on the special character of Shawha(superintending change) six meridians and the tendency of the movement change is cause by the insufficiency and excessiveness of the Bon-Qi(fundamental Qi). The Qi of the Shawha(superintending change) meridians act on the special character of Jongwha(following change) six meridians and the tendency of the movement change is cause by the exuberance of Yang and the deficiency of Yang.
12 경락(經絡)의 속성(屬性)과 운동변화(運動變化)의 경향성(傾向性)을 파악(把握)하기 위한 연구(硏究)
석동윤 ( Dong Yun Shuk ),최찬헌 ( Chan Hun Choi ),장경선 ( Kyeong Seon Jang ) 대한경락경혈학회 2000 Korean Journal of Acupuncture Vol.17 No.1
The purpose of this study is to understand the special character and the tendency of the movement change that 12 meridians possess. We studied about the incidental and fundamental rule of the six atmospheric influence that was presented by Pyobonjoong(the incidental, fundamental, intermediate) theory, and the Hwang won-uh`s the Six Channel activity of the Qi theory that presented movement form of the meridian through the six atmospheric influence. Then we found the following substances. The Pyobonjoong(the incidental, fundamental, intermediate) theory is applicable to understand the special character and the tendency of the movement change that Meridians possess. But, because the Pyobonjoong(the incidental, fundamental, intermediate) theory can`t classify the characteristic difference of the hand and foot meridians, then the principle that can devide the meridians of the hand and foot, must be supplied. The Jungwha(right changing)-Daewha(opposite changing) theory is able to concretely classify the special character of the hand and foot six meridians. And Hwang`s Shawha(superintending change)-Jongwha(following change) theory that is base on Jungwha(right changing)-Daewha(opposite changing) theory, is able to classify the special character of the hand and foot six meridians, too. If the concept of the Meridians is understood by the Shawha(superintending change)-Jongwha (following change) theory, the special character of the hand and foot six meridians could be concretely classified and then the meridian of the Bowels and the six atmospheric influence corresponded to the meridians could be expansively explained as the point that take charge and control these special Qi in the human body The Bon-Qi(fundamental Qi) act on the special character of Shawha(superintending change) six meridians and the tendency of the movement change is cause by the insufficiency and excessiveness of the Bon-Qi(fundamental Qi). The Qi of the Shawha(superintending change) meridians act on the special character of Jongwha(following change) six meridians and the tendency of the movement change is cause by the exuberance of Yang and the deficiency of Yang.
열간프레스성형에서의 변형 측정장치 개발 및 기계적 거동의 물성화
유동훈(Donghoon Yoo),석동윤(Dong-Yoon Seok),김돈건(Dongun Kim),안강환(Kanghwan Ahn),손현성(Hyun-Sung Son),김교성(Gyo-Sung Kim),정관수(Kwansoo Chung) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.10
As a way to improve the safety of automotive and to reduce the weight of vehicles, new forming technologies and advanced materials are in high demand in the automotive industry. However, the advanced strength steel has inferior formability and large springback. In order to overcome such drawbacks, the hot press forming process (HPF) has been being applied for forming of automotive sheet parts. In this work, new equipment was suggested to measure unlimited displacement range compared to previous one which was able to measure only up to 10mm displacement range. The external extensometer connected with grips by wire was applied to equipment so that total strain range was measured up to failure also in high temperature. And the finite element analysis was conducted to characterize the mechanical properties of the HPF steel. Finally, the flow curves were represented by utilizing the Johnson-Cook type equation both in uniform and post-uniform deformation regions.
안강환(Kanghwan Ahn),유동훈(Donghoon Yoo),석동윤(Dong-Yoon Seok),김홍기(HongGee Kim),박성호(SungHo Park),정관수(Kwansoo Chung) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
In order to overcome drawbacks of the advanced high strength steel such as inferior formability and large springback, the hot press forming process(HPF) has been being applied for forming of automotive sheet parts. Good formability and dimensional accuracy without springback as well as good crash performance of final products are the advantages of the HPF process. In this work, a method to characterize the mechanical properties of the HPF steel was developed based on the simple tension test at high temperatures and its finite element analysis, while it was applied to obtain strain rate and temperature dependent flow curves of the HPF steel. The final flow curves were represented by utilizing the Johnson-Cook type equation both in uniform and post-uniform deformation regions.