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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 13, Issue 3 - Dec 2015
Volume 13, Issue 2 - Aug 2015
Volume 13, Issue 1 - Apr 2015
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Biosystems Engineering Laboratory
Sim, Eun-Bo ;
Journal of the Korean Society of Visualization, volume 13, issue 1, 2015, Pages 3~5
Wind tunnel study on drag reduction of a 5 ton truck using additive devices
Lee, EuiJae ; Hwang, BaeGeun ; Kim, JeongJae ; Lee, SangJoon ;
Journal of the Korean Society of Visualization, volume 13, issue 1, 2015, Pages 9~14
DOI : 10.5407/jksv.2015.13.1.009
There have been many attempts to reduce the cost of transportation. Especially, drag reduction of heavy vehicles has enormous influence on energy saving by reducing the driving power of the vehicles. In this study, the effects of drag-reducing additive devices such as side skirt, boat tail and cab-roof fairing on the drag reduction of a 5 ton truck model were experimentally investigated. The aerodynamic performance of these flow-control devices attached to heavy vehicle was evaluated through wind tunnel test. In addition, flow patterns around the truck model were visualized by using smoke tube method. The drag coefficient is reduced by up to 5.7%, 7.16% and 22.2% by the side skirt, boat tail and cab-roof fairing, respectively. The interactive effect of the side skirt and boat tail was also investigated.
Optimized blade of small vertical axis wind turbine and its vortex structure analysis
Na, Jisung ; Ko, Seungchul ; Sun, Sanggyu ; Bang, Yusuk ; Lee, Joon Sang ;
Journal of the Korean Society of Visualization, volume 13, issue 1, 2015, Pages 15~20
DOI : 10.5407/jksv.2015.13.1.015
Sensitivity studies of blade angle and twisted angle are numerically investigated to optimize the Savonius blade. As blade angle increases, the contact area between blade and wind decreases, showing the suppression of the vortex generation near blade. Compared to the blade angle of 0 degree, the blade angle of 20 degree shows about 2.6% increment of power efficiency. Based on the blade angle of 20 degree, sensitivity studies of the twisted angle are performed. The result indicates that the adjustment of the twisted angle causes the torque of blade to increase. Optimized blade can suppress the formation of the vortex structure in rear region. Also, wind flows without disturbance of vortex when passing through the optimized blade. The 1kw vertical wind turbine system with optimized blade can generate 4442.2kWh per year and have 53% capacity factor.
Three-dimensional vortex structure near a corner of a translating plate
Kim, Daegyoum ;
Journal of the Korean Society of Visualization, volume 13, issue 1, 2015, Pages 21~25
DOI : 10.5407/jksv.2015.13.1.021
Three-dimensional vortex structures in the corner region of translating normal plates are visualized experimentally with defocusing digital particle image velocimetry. Vortex formation processes for three plates with corner angle
are compared in order to study the effect of corner shape on vortex formation. In all cases, the self-induction of the starting vortex and its interaction with the potential flow induced by the moving plate cause the vortex to change its form dynamically after the plate starts to translate. While the vortex near a corner follows the plate in the low corner angle of
, the vortex separates early from the plate and its forward motion becomes slow in the high corner angle of
. It is also found that the starting vortex can transport inward at the corner, which depends on the corner angle.
Visualization of ventilated supercavitation phenomena around a moving underwater body
Chung, Jaeho ; Cho, Yeunwoo ;
Journal of the Korean Society of Visualization, volume 13, issue 1, 2015, Pages 26~29
DOI : 10.5407/jksv.2015.13.1.026
A laboratory experiment was carried out to observe and visualize ventilated supercavitation phenomena around a moving underwater body which is attached to a newly designed high-speed (Max. 20 m/s) carriage system in a wave tank. Compared to the existing many other experimental studies using cavitation tunnels, where the body is at rest and the fluid is in motion in a bounded or closed environment, the present experimental study deals with super-cavity formation in unbounded or free-surface bounded environments, where the body is in motion and the fluid is at rest. Main attention is paid to the effective visualization of the steady-state cavity formations around a moving body and, those cavity formations are reported pictorially according to the body speed, ventilated air-pressure, and with or without a cavitator.
Numerical Study on FC-72 Condensing Flow in a Micro-Channel
Kim, Sung-Min ;
Journal of the Korean Society of Visualization, volume 13, issue 1, 2015, Pages 30~34
DOI : 10.5407/jksv.2015.13.1.030
This study concerns flow and heat transfer characteristics of FC-72 condensing flow in a micro-channel. A computational model of condensing flow with a hydraulic diameter of 1 mm is constructed using the FLUENT computational fluid dynamics code. The computed void fraction contour plots are presented for different mass velocities. The smooth-annular, wavy-annular, transition and slug flows are observed with the model, which are quite similar to those observed in a micro-channel experiment. The computed two-phase condensing heat transfer coefficient is compared with previous empirical correlation for two-phase condensation heat transfer in micro-channels.
Quantitation of Antigen-Antibody Reaction Condition for Development of Fluorescence Image-based CD4 Rapid Test
Kim, Subin ; Kim, Jung Kyung ;
Journal of the Korean Society of Visualization, volume 13, issue 1, 2015, Pages 35~42
DOI : 10.5407/jksv.2015.13.1.035
CD4+ T-cell count determines the effectiveness for antiretroviral therapy (ART) in patients with human immunodeficiency virus (HIV). Although ART slows the progression of HIV to AIDS, rapid counting of CD4+ T lymphocytes with a drop of patient's blood sample is urgently needed to ensure timely ART treatment in rural areas. Recently point-of-care CD4 testing devices have been developed by using non-flow based imaging cytometer incorporated with a sample cartridge where CD4+ T cells are reacted with fluorescently tagged specific antibodies. Here we conducted an experimental study using a conventional fluorescence microscope-based imaging system to quantitate the interaction of CD4 antibodies with CD4+ T cells at different reaction conditions. We demonstrated that a fast and affordable point-of-care CD4 test is feasible with a far less amount of antibodies and a shorter incubation time compared with a conventional sample preparation protocol for flow cytometry. We also proposed a general method to evaluate and compare the detection limit across different CD4 counting platforms by using fluorescently labelled microbeads for intensity calibration.
Visualization of mechanical stresses in expanding cell cluster
Cho, Youngbin ; Gweon, Bomi ; Ko, Ung Hyun ; Shin, Jennifer H. ;
Journal of the Korean Society of Visualization, volume 13, issue 1, 2015, Pages 43~48
DOI : 10.5407/jksv.2015.13.1.043
Collective cell migration is a fundamental phenomenon observed in various biological processes such as development, wound healing, and cancer metastasis. During the collective migration, cells undergo changes in their phenotypes from those of stable to the migratory state via the process called epithelial-mesenchymal transition (EMT). Recent findings in biology and biochemistry have shown that EMT is closely related to the cancer invasion or metastasis, but not much of the correlations in kinematics and physical forces between the neighboring cells are known yet. In this study, we aim to understand the cell migration and stress distribution within the expanding cell cluster. We constructed the in vitro cell cluster on the hydrogel, employed traction force microscopy (TFM) and monolayer stress microscopy (MSM) to visualize the physical forces within the expanding cell monolayer. During the expansion, cells at the cluster edge exhibited enhanced motility and developed focal adhesions that are the essential features of EMT while cells at the core of the cluster maintained the epithelial characteristics. In the aspect of mechanical stress, the cluster edge had the highest traction force of ~90 Pa directed toward the cluster core, which means that cells at the edge actively pull the substrate to make the cluster expansion. The cluster core of the tightly confined cells by neighboring cells had a lower traction force value (~60 Pa) but the highest intercellular normal stress of ~800 Pa because of the accumulation of traction from the edge of the monolayer.
The impact behaviors of electrified micro-droplet with existence and nonexistence of electrical charged for surface
Lee, Jaehyun ; Kim, Jihoon ; Byun, Doyoung ;
Journal of the Korean Society of Visualization, volume 13, issue 1, 2015, Pages 49~53
DOI : 10.5407/jksv.2015.13.1.049
Recently, researches for droplet impact phenomena have been faced a new phase in the direction of studying the effect of complex external conditions (e.g. wettability, temperature, morphology, electric field, etc.) for depth understanding and precise controlling in various applications. Hence, here we investigated the electrified droplet impact phenomena, because there were few quantitative researches for electrified droplet impact when we considering many real applications such as electrospray, electrohydrodynamic (EHD) jet printing. To observe interaction effect of surface charge between substrate and droplet simultaneously, micro-droplets with various Reynolds number (Re) and Weber number (We) were dripped on super-hydrophobic surface with existence and nonexistence of electrical surface charge. It shows three kinds of impact behaviors, fully bouncing, partial bouncing, and splashing with different We. Also, charged droplet bounced higher on electrically charged surface than on non-charged surface. Additionally, transition regions of three impact behaviors were classified quantitatively with water hammer pressure value, which means instant pressure inside droplet at the impact moment.