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고출력 저에너지 이온빔을 이용한 InP(100) 표면의 나노 패턴형성
박종용,최형욱,정연식,최원국,Park Jong Yong,Choi Hyoung Wook,Ermakov Y.,Jung Yeon Sik,Choi Won-Kook 한국재료학회 2005 한국재료학회지 Vol.15 No.6
InP(100) crystal surface was irradiated by ion beams with low energy $(180\~225\;eV)$ and high flux $(\~10^{15}/cm^2/s)$, Self-organization process induced by ion beam was investigated by examining nano structures formed during ion beam sputtering. As an ion source, an electrostatic closed electron Hall drift thruster with a broad beam size was used. While the incident angle $(\theta)$, ion flux (J), and ion fluence $(\phi)$ were changed and InP crystal was rotated, cone-like, ripple, and anistropic nanostrucuture formed on the surface were analyzed by an atomic force microscope. The wavelength of the ripple is about 40 nm smaller than ever reported values and depends on the ion flux as $\lambda{\propto}J^{-1/2}$, which is coincident with the B-H model. As the incident angle is varied, the root mean square of the surface roughness slightly increases up to the critical angle but suddenly decreases due to the decrease of sputtering yield. By the rotation of the sample, the formation of nano dots with the size of $95\~260\;nm$ is clearly observed.
이성재,정연식,강명창,김정석 한국공작기계학회 2004 한국생산제조학회지 Vol.13 No.4
In this study, the leak detection technique of pressure vessel by using acoustic emission(AE)signal is suggested experimentally. The leak of pressure vessel is located at the welding line due to welding defects. we measured the AE signal using R15I sensor, and examined the AE parameters in leak condition. It is investigated that the mean value of AE signal is dependent on leak source location. So the absolute mean value of AE signal is adopted as dominant AE parameter. We proposed leak detection algorithm using AE signal mean value for monitoring the leak source location.
이성재,김정석,강명창,정연식,정규동 한국공작기계학회 2003 한국공작기계학회 춘계학술대회논문집 Vol.2003 No.-
This study deals with the source location method of defect which can be occurred in structure. The existing methods was very difficult to be applied to predict it, because of using very complex numerical formula. The triangulation method which was proposed in this study can predict the source location predicted easily with small amount of data. Wave arrival time data can be directly converted into source-sensor distance is known. For this purpose, the propagation velocity was measured by Rayleigh wave, and the propagation behavior was analyzed. For the consideration of jointed part in structure, the source location method was applied to the welded workpieces. The signal propagation velocity was measured in welding part for the purpose of application to the part, and the revised algorithm of source location was proposed.