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이종형,최성대,정선환,권현규,양성현,Lee, Jong-Hyung,Choi, Seong-Dae,Cheong, Seon-Hwan,Kwon, Hyun-Kyu,Yang, Seong-Hyeon 한국기계가공학회 2004 한국기계가공학회지 Vol.3 No.4
High manganese steel was maintained stability of Non-Magnetics performance. Fatigue tests were carried out under constant stress amplitude, using a non-magnetic high manganese steel. The fatigue crack growth mechanism of the high manganese steel was clarified from results such as observation of crack growth path and fracture surface. The result of getting this study was shown as following: 1) Remarkably ${\Delta}Kth$ of the high manganese steel is big with about 3 times of the general steel product. 2) In the low ${\Delta}K$ value region, da/dN is dependent on Kmax, and in the high ${\Delta}K$ value region, it is dependent on ${\Delta}Keff$. The reason of this behavior is crack closure due to fracture surface roughness and fretting oxide. 3) It seems to ease the stress concentration of crack tip crack growth behavior in the ${\Delta}Kth$ vicinity by the generation of the secondary crack.
최성대(Seong-Dae Choi),정선환(Seon-Hwan Cheong),권현규(Hyun-Kyu Kwon),정영관(Young-Kwan Jeong),홍영배(Yong-Bae Hong) 한국산업융합학회 2007 한국산업융합학회 논문집 Vol.10 No.4
Glass-to-metal contact should be prevented in the design of any structural glass component. Because glass is extremely brittle and will fracture readily if even a small point load is applied. If the assembly includes a glass component supported by metallic structure, designers should provide a pliable interface of some kind between the two parts. But there happens high demand of glass-to metal contact in semiconductor industries due to adoption of dry cleaning process as one of the good solution to reduce running cost - carry out equipments cleaning with high corrosive and etching gas such as CF4 with keeping process temperature as the same as high service temperature. Therefore the quartz glass have to be received compression by direct contact with metal as the form of weight itself and vacuum pressure and fatigue by vibrations caused by process during the process. In this paper investigation will be carried out on fracture behavior of quartz glass contacted with metal directly under local load and fatigue given by process vibration with apparatus which can give lox\cal load and vibration through PZT ceramics to give guideline to prevent unintended fracture of quartz glass.
반도체 실리콘 웨이퍼 가공용 폴리싱머신의 구조해석에 관한연구
정선환(Seon-Hwan Cheong),최성대(Seong-Dae Choi),권현규(Hyun-Kyu Kwon),손현수(Hyon-Su Son) 한국기계가공학회 2006 한국기계가공학회 춘추계학술대회 논문집 Vol.2006 No.-
Although Korea is now the top nation to produce non-memory semi-conductors in the world, but there are lacked informations about the researches and developments for the domestic equipments to manufacture the accurate silicon wafer such as a lapping, and polishing machine. Therefore in this study, as the consideration to develop a domestic polishing machine in the future, some trials were carried out to take some basic design data being useful to improve the structure of a specified polishing machine for silicon wafer. It was focused in plate and frame part that is base part in a polishing machine. Through its' 3D modeling, and structural analysis, the problems were investigated the deformation and stress of major parts, and the improvement methods were proposed by the results of analysis. As results, the thermal deformation in plate that contacts directly with silicon wafer was dominated, and they were known that it was very important to review the design factors to get a stability of thermal, and a structural robustness, too.
최성대(Seong-dae Choi),정선환(Seon-hwan Cheong),김기만(Gi-man Kim),권현규(Hyun-kyu Kwon),김잠규(Jam-kyu Kim) 한국기계가공학회 2008 한국기계가공학회 춘추계학술대회 논문집 Vol.2008 No.-
In this study, we find that IPMC's mechanical characteristics in distilled water. Nafion is used as a base ionic polymer. IPMCs in mechanical electronic polymer are materials that are different with common actuator such as motor have bending work, working in low voltage, lightness, flexibility, and actuation within liquid. The nature of IPMC characteristics with the muscle of the human being the nature which is similar having the possibility which as the organism imitation style activator and the sensor is infinite. In order to examine like this possibility we try to investigate the examples which experiments from different data and application methods, actually Nafion 177 and an experiment about the answer back quality which follows in standard, impressed voltage and authorization frequency and used IPMC where comes to make the gold with the basic material and from distilled water inside environment, the result of we accomplished we produced.
혼합모드(Ⅰ+Ⅱ)에서 피로균열진전에 미치는 응력비의 영향
공병채(Byeong-Chae Gong),최명수(Myoung-Su Choi),권현규(Hyun-Kyu Kwon),최성대(Seong-Dae Choi) 한국기계가공학회 2009 한국기계가공학회지 Vol.8 No.4
The loading condition of actual construction works is complex. The shear effect of mixed-mode load component are crack propagation mechanism in step larger than the crack initial mechanism. Therefore, in this study received a mixed-mode loading on fatigue crack stress ratio on crack propagation path and speed of progress to leam whether stress affects crack propagation. ? P a constant state of fatigue tests in Mode I, II give the same stress ratio, frequency 10㎐, sinusoidal waveform was used. A lower stress ratio fatigue crack propagation angle is small. This is less affected by the Mode II. Therefore, a mixed-mode fatigue crack propagation is to progress by the Mode. Stress ratio in a mixed mode crack in the path of progress and found a lot of impact.