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한주호(J. H. Han),김효정(H. J. Kim),임현규(H. K. Lim),정연찬(Y. C. Chung) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.5
Feature Line which exists outside of the car looks like a line as the result of the remarkably small radius compared with surroundings. Feature line usually express the aesthetical characteristics like makes the body of car look smooth and massing. Also, Feature line’s position and visual thickness are very important quality elements for outside parts of the car. But they usually pass about the Feature line without definite evaluation in existing verification process. So, there should be the research about visual analysis to know the exact allowable error range of Feature line in the evaluation process. For that, it is necessary to make some samples. However making samples of Feature Line is so difficult in some reasons. First of all, samples and car body’s surface illumination should be same. Second, the shape of Feature line is so tiny. Last, Feature Line’s surface part is made of free curves. In this research, we make samples with RP, Wire-EDM, and CNC Milling, compare whether the samples’ each elements are correctly expressed or not, and finally we found that CNC Milling is the best method to express the Feature Line.
ECO AM30 마그네슘 합금의 인장, 고주기 피로 및 피로 균열 전파 변형 거동
김민종(M. J. Kim),김세광(S. K. Kim),임현규(H. K. Lim),박중철(J. C. Pack),이기안(K. A. Lee) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.5
Tensile and fatigue deformation behaviors of newly developed ECO AM30 alloy was investigated. Microstructure analysis,tensile, high cycle fatigue, fatigue crack propagation tests were conducted. In the microstructure observation, average grain size was 5.8㎛ for AM30 alloy (conventional reference material) and 2.5 ㎛ for ECO AM30 alloy. ECO alloy consisted of Mg matrix containing minute amounts of Mg17Al12, Al6Mn, Mg32(Al, Zn)49, and Al₂Ca phases. Tensile results showed that the properties of ECO AM30 alloy (T.S: 313.8MPa, Y.S: 184.3MPa, elongation: 21.3%) were superior to those of AM30 alloy (T.S: 310.2MPa, Y.S: 177.3MPa, elongation: 16.5%). High cycle fatigue limit of AM30 (set at 10<SUP>7</SUP> cycles) was 130 MPa and that of ECO AM30 alloy was 170 MPa. Result of fatigue crack propagation experiment, both alloys showed similar fatigue crack propagation rate. Better tensile and fatigue properties of ECO AM30 alloy is mainly due to the refined grains and homogeneously distributed fine strengthening particles.
ECO AZ31 마그네슘 합금의 인장, 고주기 피로 및 피로 균열 전파 변형 거동
김민종(M. J. Kim),김관영(K. Y. Kim),김세광(S. K. Kim),임현규(H. K. Lim),박중철(J. C. Pack),이기안(K. A. Lee) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.5
Tensile and fatigue deformation behaviors of newly developed ECO AZ31 alloy was investigated. Microstructure analysis, tensile, high cycle fatigue, fatigue crack propagation tests were conducted. In the microstructure observation, average grain size was 3.2㎛ for AZ31 alloy and 2.7㎛ for ECO AZ31 alloy. Alloys consisted of Mg matrix containing minute amounts of Mg17Al12, Al6Mn, Mg12(Al, Zn)49phases. Tensile results showed that the properties of ECO AZ31 alloy (T.S: 314.6MPa, Y.S: 188.7MPa, elongation: 20.2%) were superior to those of AZ31 alloy (T.S: 306.4MPa, Y.S: 177.6MPa, elongation: 17.7%). High cycle fatigue limit of AZ31 (set at 10<SUP>7</SUP> cycles) was 140MPa and that of ECO AZ31 alloy was 160MPa. Result of fatigue crack propagation experiment, both alloys showed similar fatigue crack propagation rate. The cause of better properties the new ECO alloy was also discussed based on the fractography observations.
레이저 충격파 클리닝에서 발생되는 유동장의 실험적 해석
임현규,장덕석,김동식 한국레이저가공학회 2004 한국레이저가공학회지 Vol.7 No.1
The dynamics of laser-induced plasma/shock wave and the interaction with a surface in the laser shock cleaning process are analyzed by optical diagnostics. Shock wave is generated by a Q-switched Nd:YAG laser in air or with N_(2), Ar, and He injection into the focal spot. The shock speed is measured by monitoring the photoacoustic probe-beam deflection signal under different conditions. In addition, nanosecond time-resolved images of shock wave propagation and interaction with the substrate are obtained by the laser-flash shadowgraphy. The results reveal the effect of various operation parameters of the laser shock cleaning process on shock wave intensity, energy-conversion efficiency, and flow characteristics. Discussions are made on the cleaning mechanisms based on the experimental observations.