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DC 마그네트론 스퍼터링법으로 제조된 Tio<sub>2</sub> 박막의 산소분압비에 따른 광분해 특성에 관한 연구
정운조,박중윤,박계춘,Jeong, W.J.,Park, J.Y.,Park, G.C. 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.3
This paper describes the photocatalytic degradation properties by oxygen partial pressure for TiO$_2$ thin films fabricated by dc magnetron reactive sputtering. And the structural, chemical, optical and photocatalytic properties were investigated at various analysis system. When TiO$_2$ thin film was made at deposition time of 120 min and Ar:O$_2$ ratio of 60:40, the best properties were obtained. That results were as follows: thickness; 360∼370 nm, gram size; 40 nm, optical energy band gap; 3.4 eV and Benzene conversion in the photocatalytic degradation; 11 %.
A NUMERICAL STUDY ON JET IMPINGEMENT OF PULSED PLASMA DISCHARGE ON A FLAT PLATE
K. Kim(김경진),H.S. Kwak(곽호상),J.Y. Park(박중윤) 한국전산유체공학회 2009 한국전산유체공학회지 Vol.14 No.1
In this study, time-dependent numerical analysis was carried out to investigate the plasma jet impingement on a flat plate, and a compressible form of two-dimensional in viscid gas dynamics equations were solved using the flux corrected transport algorithm. The mathematical modeling of Joule heating in the polycarbonate capillary bore and the mass ablation from the bore wall was incorporated in the numerical analysis and the series of computation was performed for three cases depending on the distance of the opposing plate from the capillary exit. The computational results reveal that the presence of the opposing plate does not affect the flow conditions inside the capillary when compared to the case of open-air plasma discharge. In the exterior region, the flow structure shows the typical supersonic underexpanded jet which consists of the strong Mach disk in front of the opposing plate and the barrel shock at the side of the jet. It is found that the shock evolution becomes more quasi-steady when the plate distance decreases. Also, the effects of the distance between the capillary bore exit and the opposing plate on the flow conditions along the opposing plate are investigated and the pressure variation on the plate shows more complicated interaction between the plasma discharge and the opposing plate when the location of plate becomes closer to the capillary exit.
K. Kim(김경진),H. S. Kwak(곽호상),J. Y. Park(박중윤) 한국전산유체공학회 2014 한국전산유체공학회지 Vol.19 No.4
This computational study features the transient compressible and inviscid flow analysis on a metallic plasma discharge from the opposing composite electrodes which is subjected to pulsed electric power. The computations have been performed using the flux corrected transport algorithm on the axisymmetric two-dimensional domain of electrode gap and outer space along with the calculation of plasma compositions and thermophysical properties such as plasma electrical conductivity. The mass ablation from aluminum electrode surfaces are modeled with radiative flux from plasma column experiencing intense Joule heating. The computational results shows the highly ionized and highly under-expanded supersonic plasma discharge with strong shock structure of Mach disk and blast wave propagation, which is very similar to muzzle blast or axial plasma jet flows. Also, the geometrical effects of composite electrodes are investigated to compare the amount of mass ablation and penetration depth of plasma discharge.
채터 진단을 위한 채터 주파수-회전 속도 선도의 활용에 대한 연구
이상호,이대형,박중윤,홍성욱 金烏工科大學校 2000 論文集 Vol.21 No.-
This paper presents a method to identify the on-set of chatter, using the chatter frequency-spindle speed diagram, for a milling spindle-workpiece system in face milling process. To this purpose, the eigenvalue problem approach using frequency response function is adopted for predicting both the chatter condition and chatter frequency. The chatter frequency-spindle speed diagram for various conditions is investigated throughout simulation and experiment to diagnose the chatter. The simulation and experimental results show that the chatter frequency-spindle speed diagram is useful for diagnosis of the on-set of chatter vibration.