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ALE 유한요소법에 의한 충돌 액체 분류 냉각 유동 특성 해석
성재용,최형권,유정열,Sung, Jaeyong,Choi, Hyoung Gwon,Yoo, Jung Yul 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.1
The fluid flow and heat transfer in a thin liquid film are investigated numerically. The flow Is assumed to be two-dimensional laminar and surface tension is considered. The most important characteristics of this flow is the existence of a hydraulic jump through which the flow undergoes very sharp and discontinuous change. Arbitrary Lagrangian-Eulerian(ALE) method is used to describe moving free boundary and a modified SIMPLE algorithm based on streamline upwind Petrov-Galerkin(SUPG) finite element method is used for time marching iterative solution. The numerical results obtained by solving unsteady full Navier-Stokes equations are presented for planar and radial flows subject to constant wall temperature or constant wall heat flux, and compared with available experimental data. It Is discussed systematically how the inlet Reynolds and Froude numbers and surface tension affect the formation of a hydraulic jump. In particular, the effect of temperature dependent fluid properties is also discussed.
단일 카메라의 영상분리를 이용한 자유 상승 기포의 고속 이상 유동 PIV 계측
성재용(Jaeyong Sung),박상민(Sang Min Park),유정열(Jung Yul Yoo) 한국가시화정보학회 2004 한국가시화정보학회지 Vol.2 No.1
A time-resolved two-phase PIV system using a single camera has been developed, which introduces a method of image separation into respective phase images, and is applied to freely rising single bubble. Gas bubble, tracer particle and background have different gray intensity ranges on the same image frame when reflection and dispersion in the phase interface are intrinsically eliminated by optical filters and fluorescent particles. Further, the signals of the two phases do not interfere with each other. Gas phase velocities are obtained from the separated bubble image by applying the two-frame PTV. On the other hand, liquid phase velocities are obtained from the tracer particle image by applying the cross-correlation algorithm. As a result, the bubble rises rectilinearly just after it is released from an injector and then has a zigzag motion in the far field. From the trajectory of the bubble, it is found that the period of the zigzag motion is closely related to the vortex shedding although the wavelength of it varies along its movement.
성재용(Jaeyong Sung),도덕희(Deog Hee Doh),이석종(Sukjong Lee),황태규(Tae Gyu Hwang) 한국가시화정보학회 2006 한국가시화정보학회지 Vol.4 No.2
An experimental apparatus for PIV performance evaluation has been developed. Stardard uncertainty of a two-dimensional cross-correlation PIV system was investigated based upon the standard experimental apparatus, which was devised to model the rigid body rotating flows. For the systematic analysis of the uncertainty introduced by each component (algorithm, CCD camera, frame grabber) of the PIV system, standard images are fed into the component independently. The standard experiments show that 53% of the uncertainty in the present PIV system results from the frame grabber but the errors from the algorithm and digital camera are ignorable.
OLED 박막 증착공정에서 유도로 내부의 분자유동 해석
성재용(Jaeyong Sung),이응기(Eungki Lee) 한국생산제조학회 2007 한국공작기계학회 춘계학술대회논문집 Vol.2007 No.-
Molecular flows inside a guide block in the OLED (organic luminescent emitting device) deposition process have been simulated using DSMC (direct simulation Monte Carlo) method. Because the organic materials are evaporated under vacuum, the molecules flow at a high Knudsen number of the free molecular regime, where the continuum mechanics is not valid. The guide block is designed as a part of the linear cell source to transport the evaporated materials to a deposition chamber. When solving the flows, the inlet boundary condition is proved to affect significantly the whole flow pattern. Thus, it is proposed that the pressure should be specified at the inlet. From the analysis of the density distributions at the nozzle exit of the guide block, it is shown that the longer nozzle can emit molecules more straightly. Finally, a nondimensionalized mass flow profile is obtained by the numerical experiments, where various nozzle widths and inlet pressures are tested.
성재용(Jaeyong Sung),안광협(Kwang Hyup An),이기섭(Gi Seop Lee),최호선(Ho Seon Choi),이인섭(In-Seop Lee) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
Fluid flows discharged from a 4-way ceiling type indoor unit has been visualized for various vane angles<br/> using a PIV(particle image velocimetry) system. Then, optimal vane angle has been suggested for the best<br/> thermal comport. For the PIV measurements, a 1/10 scale experimental model with a transparent room was<br/> devised by satisfying the Archimedes number. The results of flow visualizations show that the vane angle<br/> should be less than 30° to avoid re-suction flows and to prevent the main stream being concentrated near the<br/> occupant’s head. However, at the smaller angles, flow induced noise increases. Thus, the vane angle of 30°<br/> has been suggested as an optimum. Temperature distribution measured in the environmental chamber also<br/> indicates that it is profitable for the warm flow near one’s feet.
치아 근관 세척용 마이크로 기포 세정 시스템 개발 및 성능평가
성길환(Gilhwan Sung),성재용(Jaeyong Sung),이명호(Myeong Ho Lee) 한국가시화정보학회 2016 한국가시화정보학회지 Vol.14 No.1
Elimination of the smear layer and bacteria in the root canal is the most important in the endodontic treatment, and various irrigation devices have been developed. Nevertheless, it is hard to eliminate the smear layer and bacteria completely. In this paper, a micro bubble irrigation system has been developed for the root canal cleaning of tooth. Micro bubbles are generated when pressurized fluids passing through a porous material inside a hand-piece nozzle, and the bubbly flows excited by ultrasonic vibration are observed using a high-speed camera and a microscope. The results show that the diameter and number of bubbles increases with the applied pressure, and there found an optimum excitation frequency in order to minimize the bubble size. From in-vitro tests, it is also verified that the developed bubble irrigation system has the ability of antibacterial and infection removal. Thus, this biocompatible system would be well suited for root canal cleaning.