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Fe-28Mn-2Al-3Si 합금의 진동 감쇠능에 관한 연구
권민기(M. K. Kwon),박영태(Y. T. Park),조덕호(D. H. Cho),강창룡(C. Y. Kang) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The effect of the damping capacity of Fe-28Mn-2Al-3Si alloy has been investigated after changing the microstructure by cold rolling. Microstructures in Fe-28Mn-2Al-3Si at room temperature consist of a large quantity of austenite and small quantities of ε and α' martensites. And ε and α' martensites were increased by increasing the degree of cold rolling. With increasing the grain size, the volume fraction of martensite was increased which transformed from the austenite by the cold rolling. Damping capacity was linearly increased with increasing the degree of rolling due to transforming austenite to martensite by deformation. Damping capacity is strongly affected by ε martensite than α' martensite making by deformation induced martensite.
오스템퍼링 처리한 구상흑연주철의 기계적 성질 및 감쇠능에 미치는 Cu의 영향
이광희(K. H. Lee),박영태(Y. T. Park),권민기(M. K. Kwon),강창룡(C. Y. Kang) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
This study was investigated the effect of Cu contents in austempered ductile cast iron. The volume fraction of retained austenite and the carbon contents of retained austenite was shown the greatest value at 400℃. In case of specimens has much Cu contents, the volume fraction of retained austenite and the carbon contents in retained austenite shows the low value. Tensile strength and impact value increased and elongation decreased by austempering treatment. With increasing austempering temperature, tensile strength increase, elongation and impact value decreased. In case of specimen with more of Cu contents, tensile strength showes the higher value and elongation was low value. Damping capacity decreased by austempering treatment and damping capacity of austempered ductile cast iron be not affect austempering temperature and time. In case of specimen with more of Cu contents, damping capacity shows the high value.
김자연,박성주,문영부,권민기,Kim, J.Y.,Park, S.J.,Moon, Y.B.,Kwon, M.K. 한국진공학회 2011 Applied Science and Convergence Technology Vol.20 No.4
본 논문은 고휘도 발광소자의 특성을 높이기 위한 p-GaN 박의 홀농도 향상을 연구하였다. 우리는 metal organic chemical vapor deposition 법을 이용하여 Antimony (Sb)가 p-GaN의 홀농도 향상에 도움을 주는 것을 확인하였다. Atomic force microscope 측정을 통해 Sb가 계면활성제처럼 역할을 함으로써 p-GaN의 2차원 성장이 촉진됨을 알 수 있었다. 또한 X-ray diffraction 결과 [002] 면과 [102] 면의 반폭치가 Sb 도핑과 함께 줄어드는 것을 통해 Edge과 Screw 전위의 감소와 photoluminescence 결과에서 450~500 nm 청색 파장 영역에서 발광의 세기가 현저히 줄어드는 것으로 보아 질소 공극이 감소되는 것이 홀농도 향상의 주된 원임임을 알 수 있었다. Trimethylantimony가 10 ${\mu}mol/min$일 때 홀농도는 최대가 되었고 그때 홀농도는 $5.4{\times}10^{17}cm^{-3}$이었다. The role and effect of Sb surfactant on structure and properties of p type gallium nitride (GaN) epilayers have been investigated. It was found that there was a increase of hole concentration with Sb surfactant, compared to typical Mg-doped p-GaN. The structural and optical quality of p-GaN epilayers were accessed by x-ray diffraction, photoluminescence and atomic force microscope measurements. The results clearly show that the increase in hole concentration with Sb surfactant can be resulted from decrease in the dislocations and nitrogen point defects.