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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Visualization
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The Korean Society of Visualization
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Volume & Issues
Volume 9, Issue 4 - Dec 2011
Volume 9, Issue 3 - Sep 2011
Volume 9, Issue 2 - Jun 2011
Volume 9, Issue 1 - Mar 2011
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한국항공대학교 응용공기역학연구실(Applied Aerodynamics Laboratory)
Jang, Jo-Won ;
Journal of the Korean Society of Visualization, volume 9, issue 1, 2011, Pages 8~16
Visualization of Disruptive Bubble Behavior in Ultrasonic Fields
Kim, Tae-Hong ; Park, Keun-Hwan ; Kim, Ho-Young ;
Journal of the Korean Society of Visualization, volume 9, issue 1, 2011, Pages 17~19
DOI : 10.5407/JKSV.2011.9.1.017
The bubble oscillations play an important role in ultrasonic cleaning processes. In the ultrasonic cleaning of semiconductor wafers, the cleaning process often damages micro/nano scale patterns while removing contaminant particles. However, the understanding of how patterns in semiconductor wafers are damaged during ultrasonic cleaning is far from complete yet. Here, we report the observations of the motion of bubbles that induce solid wall damage under 26 kHz continuous ultrasonic waves. We classified the motions into the four types, i.e. volume motion, shape motion, splitting or jetting motion and chaotic motion. Our experimental results show that bubble oscillations get unstable and nonlinear as the ultrasonic amplitude increases, which may exert a large stress on a solid surface raising the possibility of damaging microstructures.
PIV Investigation on the Skin Friction Reduction Mechanism of Outer-layer Vertical Blades
Park, Hyun ; An, Nam-Hyun ; Park, Seong-Hyoen ; Chun, Ho-Hwan ; Lee, In-Won ;
Journal of the Korean Society of Visualization, volume 9, issue 1, 2011, Pages 20~28
DOI : 10.5407/JKSV.2011.9.1.020
An experimental assessment has been made of the drag reducing efficiency of the outer-layer vertical blades, which were first devised by Hutchins. The drag reduction efficiency of the blades was reported to reach as much as 30%. However, the drag reduction efficiency was quantified only in terms of the reduction in the local skin-friction coefficient. In the present study, a series of drag force measurements in towing tank has been performed toward the assessments of the total drag reduction efficiency of the outer-layer vertical blades. A maximum 9.6% of reduction of total drag was achieved. The scale of blade geometry is found to be weakly correlated with outer variable of boundary layer. In addition, detailed flow field measurements have been performed using 2-D time resolved PIV with a view to enabling the identification of drag reduction mechanism.
Visualization and Velocity Measurement of Migrating Cells in Microchannels with Various Width
Lee, Seung-Youl ; Kim, Myung-Jun ; Chae, Sang-Min ; Jin, Song-Wan ;
Journal of the Korean Society of Visualization, volume 9, issue 1, 2011, Pages 29~35
DOI : 10.5407/JKSV.2011.9.1.029
In this paper, we applied various microfluidic chambers to visualize cell migration and measured the migration velocity in microchannels. Migration speed of B16 cell in a large channel was similar with that of wound healing experiment. However, the speed decreased gradually as the cell move inside of the channel. It is expected that this phenomenon is due to the shortage of oxygen or nutrition, whichare essential for cell growth. In the case of cell in the small channel whose size is smaller than the cell, its speed was slower than that in a larger channel.
Quantitative Visualization of Dissolved Oxygen Concentration Field in Micro Flows using PtOEP/PS Membrane
Song, Dae-Hun ; Kim, Hyun-Dong ; Kim, Kyung-Chun ;
Journal of the Korean Society of Visualization, volume 9, issue 1, 2011, Pages 36~41
DOI : 10.5407/JKSV.2011.9.1.036
It is highly needed to measure the dissolved oxygen (DO) concentration field in water for a variety of purposes such as biological, industrial, environmental monitoring and medical application. Application of PSP (Pressure Sensitive Paint) which is sensitive to oxygen concentration has been carried out to measure DO concentration field using PtOEP/PS film and intensity based method under the UV-LEDs illumination. A micro round water jet having 100% of DO was obliquely impinged on to a PtOEP/PS film coated plate placed in a 0% of DO water container. DO concentration fields on the impinging plate were quantitatively visualized with a
of spatial resolution. Through pixel-by-pixel calibration, uncertainty of each pixel by different sensitivity, different dye concentration and non-uniformity of illumination was removed. It is demonstrated that the high DO concentration region was coincided with the impingement area. The DO concentration gradient due to DO diffusion was affected by Reynolds number.
A Study on Combustion Characteristic Methane Fuel according to Torch Volume Variation in a Constant Volume Combustion Chamber
Kwon, Soon-Tae ; Park, Chan-Jun ; Ohm, In-Young ;
Journal of the Korean Society of Visualization, volume 9, issue 1, 2011, Pages 42~48
DOI : 10.5407/JKSV.2011.9.1.042
Six different size of torch-ignition device were applied in a constant volume combustion chamber for evaluating the effects of torch-ignition on combustion. The torch-ignition device was designed for six different volumes and same orifice size. The combustion pressures were measured to calculate the mass burn fraction and combustion enhancement rate. In addition, the flame propagations were visualized by shadowgraph method for the qualitative comparison. The result showed that the combustion pressure and mass burn fraction were increased when using the torch ignition device. And the combustion duration were decreased. The combustion enhancement rates of torch-ignition cases were improved in comparison with conventional spark ignition. Finally, the visualization results showed that the torch-ignition induced faster burn than conventional spark ignition due to the earlier transition to turbulent flame and larger flame surface, during the initial stage. Finally, the initial flame propagation was affected by torch-ignition volume.
Flow Analysis in a Rotating Container with Axial Injection and Radial Ejection
Park, Jun-Sang ; Sohn, Jin-Gug ;
Journal of the Korean Society of Visualization, volume 9, issue 1, 2011, Pages 49~54
DOI : 10.5407/JKSV.2011.9.1.049
An investigation has been made of a viscous incompressible flow in a circular cylindrical tank. The flow is driven by the spinning bottom disk of tank together with/without central injection and radial uniform-ejection through the sidewall. Numerical solutions of steady and unsteady flows to 3-dimensional Navier-Stokes equation were obtained for several cases of injection strength. In a moderate flow rate of injection, the mass transfer occurs through the boundary layers but, as the flow rate increases, the inner region far from the container walls takes part in mass transfer.
Spray Angle and Break-up Characteristics of Supersonic Liquid Jets by an Impinging Methods with High Speed Projectile
Lee, In-Chul ; Shin, Jeung-Hwan ; Kim, Heuy-Dong ; Koo, Ja-Ye ;
Journal of the Korean Society of Visualization, volume 9, issue 1, 2011, Pages 55~60
DOI : 10.5407/JKSV.2011.9.1.055
Pulsed supersonic liquid jets injected into an ambient air are empirically studied by using a high pressure ballistic range system. Ballistic range systems which are configured with high-pressure tube, pump tube, launch tube and liquid storage nozzle. Experimental studies are conducted to use with various impact nozzle geometry. Supersonic liquid jets are generated by an impact of high speed of the projectile. High speed liquid jets are injected with M = 3.2 which pressure is 1.19 GPa. Multiple jets which accompany with shock wave and pressure wave in front of the jet were observed. The shock-wave affects significantly atomization process for each spray droplets. As decreasing orifice diameter, the averaged SMD of spray jets had the decreasing tendency.