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[論文] 정4각 덕트 入口領域에서 遷移脈動流動의 速度分布와 入口길이에 關한 硏究
유영태(Y.T.Yoo),모양우(Y.W.Moh),홍성삼(S.S.Hong) 한국자동차공학회 1993 오토저널 Vol.15 No.2
In the present study, the velocity profiles and entrance length of developing transitional pulsating flows are investigated both analytically and experimentally in the entrance region of a square duct. The systems of conservation equations for transitional pulsating flows in a square duct are solved analytically by linearizing the non-linear convective terms. Analytical solutions are obtained in the form of infinite series for velocity pofiles.<br/> The experimental study for the air flow in a square duct(40mm×40mm×4000mm) is carried out to measure velocity profiles and other parameters by using a hot-wire anemometer with a data acquisition and processing system.<br/> The distribution of velocity profiles(u??,/U??,) in the decelerating period is higher than in the accelerating period. The distribution of the axial component of the axial component of velocity in the transitional flow is nearly uniform in the central region of the duct, and decrease rapidly near the wall. The entrance length correlation of the transitional pulsating flows in a square duct is obtained to be L?/D= O. 83 A? Re?/( W+)²
유압관로에서 원통형 초크의 비정상 유동의 주파수 특성에 관한 연구
박선종,유영태,위광환,Park, S.J.,Yoo, Y.T.,Wee, K.H. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.3
A new instantaneous flowmeter for hydraulics by means or cylindrical chokes is developed. In this method the instantaneous flowrate through chokes is predicted in real time from measurement of pressure difference on both sides of cylindrical choke. The experimental study for the flowrate of pulsating flow in a pipe is carried out to measure differential pressure drop by using a strain gauge pressure transducer with data acquisition and processing system. A pulsating flow is verified by a visualization method. In the present study, the flow characteristic variables of laminar pulsating flow are investigated analytically and experimentally in a circular pipe. Characteristic parameters of ratio of inertia term to pressure term($\phi_{t.1}$) and ratio of viscous term to pressure term($\phi_{z.1}$) are introduced to describe the flow pattern of laminar pulsating flow.
연속파 Nd:YAG 레이저를 이용한 중탄소강의 다층 박판 용접 특성
양윤석(Y. S. Yang),황찬연(C. Y. Hwang),유영태(Y. T. Yoo) 한국생산제조학회 2011 한국생산제조시스템학회 학술발표대회 논문집 Vol.2011 No.4
Laser welding of metals has been widely used in industrial parts. The objective of this research works is to investigate the influence of the process parameters, such as the welding for metals with CW Nd:YAG lasers. In order to quantitatively examine the characteristics of the lap welding, the welding quality of the cut section, stain-stress behavior and the hardness of the welded part are investigated. From the results of the investigation, it has show that a good welding quality is 1600~1800W of the laser power, and 1.2~1.6m/min of laser welding speed.
4각 덕트의 입구영역에서 천이 정상유동의 입구길이에 관한 연구
박길문,유영태,고영하,Park, G.M.,Yoo, Y.T.,Koh, Y.H. 대한설비공학회 1990 설비공학 논문집 Vol.2 No.1
In the present study, the entrance length, velocity profiles and waveforms of developing transitional steady flows in a square duct are investigated analytically and experimentally. The systems of conservation equations for transitional steady duct flows are solved analytically by linearizing non-linear convective terms and adoption of modified eddy viscosity from empirical correlations. Analytical solutions of velocity profiles for developing transitional steady flow were obtained in the form of infinite series. The experimental study for transitional steady flow in a square duct with $40mm{\times}40mm{\times}4000mm$($width{\times}height{\times}length$) was carried out to measure velocity profiles and other parameters by using a hot-wire anemometer with data acquisition and processing system. The entrance length of developing transitional steady flows in a square duct was $L_e{\fallingdotseq}0.02{\cdot}Re,st{\cdot}D_h$, and the overshoot was occured at about 30 times of hydraulic diameter because of the effect of external velocity of boundary layer and instantaneous acceleration.