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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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Journal DOI :
The Korean Society of Visualization
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Volume & Issues
Volume 6, Issue 2 - Dec 2008
Volume 6, Issue 1 - Jun 2008
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Measurements of the Cylinder Wake with a Hybrid-Fitness Function based 3D-PTV
Doh, Deog-Hee ; Jo, Hyo-Jae ; Baek, Tae-Sil ;
Journal of the Korean Society of Visualization, volume 6, issue 2, 2008, Pages 3~8
DOI : 10.5407/JKSV.2008.6.2.003
A new 3D-PTV algorithm(a Volume PTV) based upon a hybrid fitness function has been constructed. A coherency fitness function is introduced using the information of space and time to sort out the correct particle pairs between the two camera images. The measurement system consists of two-high-definition-cameras(
), a Nd-Yag laser and a host computer. The developed algorithm has been employed to investigate the flow features of the cylinder wake. The Reynolds numbers with the cylinder diameter(d=10 mm) are 360, 540, 720, 900, 1080 and 1260. Two-dimensional displacements of the particles of each camera's image and neighbouring constraints were introduced to reduce the calculation loads. More than 10,000 instantaneous 3D vectors have been obtained by the constructed algorithm. The constructed algorithm could recover more than
of the particle numbers in the image condition.
Visualization of Drop Formation and Droplet Velocity Measurement of a Piezoelectric-type Inkjet
Kwon, D.H. ; Choi, Y.S. ; Lee, S.J. ;
Journal of the Korean Society of Visualization, volume 6, issue 2, 2008, Pages 9~13
DOI : 10.5407/JKSV.2008.6.2.009
The reproducibility of water droplet formation which is indispensible in the investigation of a drop-on-demand piezoelectrically driven inkjet was verified by checking the size of droplet and distance from the nozzle tip of inkjet head to droplet. Based on the reproducibility of droplet formation, we visualized the formation of micro-scale droplets by acquiring consecutive images at the jetting frequency of 500 Hz for which air bubbles were not generated. Two different electric waveforms were used to drive the piezoelectric actuator. The visualization system consists of a high-speed camera that can capture images up to 250,000fps, a long-distance microscope and a halogen lamp as a light source.
Characteristics of Bubble-driven Flow with Varying Flow Rates by Using Time-resolved PIV and POD Technique
Yi, Seung-Jae ; Kim, Jong-Wook ; Kim, Hyun-Dong ; Kim, Kyung-Chun ;
Journal of the Korean Society of Visualization, volume 6, issue 2, 2008, Pages 14~19
DOI : 10.5407/JKSV.2008.6.2.014
In this paper, the recirculation flow motion and mixing characteristics driven by air bubble flow in a rectangular water tank is studied. The Time-resolved PIV technique is adopted for the quantitative visualization and analysis. 532 nm Diode CW laser is used for illumination and orange fluorescent particle images are acquired by a PCO 10bit high-speed camera. To obtain clean particle images, 545 nm long pass optical filter and an image intensifier are employed and the flow rates of compressed air is changed from 2 l/min to 4 l/min at 0.5 MPa. The recirculation and mixing flow field is further investigated by the POD analysis technique. It is observed that the large scale counterclockwise rotation and main vortex is generated in the upper half depth from the free surface and one quarter width from the sidewall. When the flow rates are increased, the main vortex core is moved to the side and bottom wall direction.
Investigation on Grain Image Visulalization and Color Sorting Technique
Lee, Choon-Young ; Yan, Lei ; Lee, Sang-Ryong ; Par, Cheol-Woo ;
Journal of the Korean Society of Visualization, volume 6, issue 2, 2008, Pages 20~27
DOI : 10.5407/JKSV.2008.6.2.020
The color sorting technique utilizing the image processing method is very applicable tool to analyze motion of a free-falling object in many agricultural and industrial research fields. In the present study, we have developed an image processing system and algorithm to sort good quality rice grains effectively from the bad ones. The system employs a high speed rate line-scan CCD camera with 2K-pixels and worked with a high speed DSP and FPGA in-line. It can accumulate acquired line-scan image data and visualize each grain image clearly. As a result, we can easily calculate the number of pixels occupied by grain(=grain size), gray level and its correct position by visualizing grain images rapidly.
A Similarity of the Velocity Profiles According to Water Depth in Partially Filled Circular Pipe Flows
Yoon, Ji-In ; Kim, Young-Bae ; Sung, Jae-Yong ; Lee, Myeong-Ho ;
Journal of the Korean Society of Visualization, volume 6, issue 2, 2008, Pages 28~32
DOI : 10.5407/JKSV.2008.6.2.028
Contrary to the flow rate in fully filled pipe flows, the flow rate in partially filled pipe flows is significantly influenced by the variation of water level, channel slop, and so on. The major difference in these two flows results from the existence of a free surface. To make it clear, in the present study, a similarity of the velocity profile in a partially filled circular pipe has been investigated according to the water level. A particle image velocimetry (PIV) technique was applied to measure the three-dimensional velocity profiles. As a result, there is found a similarity of the velocity profile near the central region. However, near the side wall, the similarity is broken due to the interaction between the wall and the free surface.
Experimental Study of the Axial Slit Wall and Radial Temperature Gradient Effect on Taylor-Couette Flow
Lee, Sang-Hyuk ; Kim, Hyoung-Bum ;
Journal of the Korean Society of Visualization, volume 6, issue 2, 2008, Pages 33~38
DOI : 10.5407/JKSV.2008.6.2.033
The effect of the radial temperature gradient and the presence of slits in the wall of outer of two cylinders involved in creating a Taylor-Couette flow was investigated by measuring the velocity field inside the gap. The slits were azimuthally located along the inner wall of the outer cylinder and the number of slits used in this study was 18. The radius ratio and aspect ratio of the models were 0.825 and 48, respectively. The heating film wrapped around the inner cylinder was used for generating the constant heat flux and we ensured the constant temperature condition at the outer space of the outer cylinder. The velocity fields were measured by using the PIV(particle image velocimetry) method. The refractive index matching method was applied to remove image distortion. The results were compared with plain wall configuration of Taylor-Couette flow. From the results, the presence of slits in the wall of outer cylinder and temperature gradient increased the flow instability.
Research on the Airflow and Air Entrainment on Roll-to-Roll System
Kim, Sung-Kyun ; Park, Joon-Hyung ; Liem, Huynh Quang ;
Journal of the Korean Society of Visualization, volume 6, issue 2, 2008, Pages 39~44
DOI : 10.5407/JKSV.2008.6.2.039
The Roll-to-Roll system including continuous flexible thin materials and roller has its wide range of applications especially in the electronic printing industry. The industry is growing rapidly and the printing speed is also improving. However, the printing machine based on web and roller system has it own problem. As the web speed increases, the failure to maintain the contact may occur and the air entrain between the roller and the paper web may exist. Air bubbles may remain attached to electronic ink on the web causing defects on product surface. With the development of image processing technique, the airflow around the web and rolls can be visualized and calculated by PIV method. In our experiment, the simple web and rolls system is used to R2R simulator. The flow field is studied at various web speeds and positions. The result shows that the flow field has complicated structure with turbulent characteristic and the main trend of flow is obtained by taking time average of flow field.
Behavior of Bacteria on the Porous Substrates: Diffusion Effect
Cho, Myoung-Ock ; Cho, Ji-Yong ; Park, Eun-Jung ; Lee, Dong-Hee ; Lee, Jeong-Hoon ; Kim, Jung-Kyung ;
Journal of the Korean Society of Visualization, volume 6, issue 2, 2008, Pages 45~50
DOI : 10.5407/JKSV.2008.6.2.045
It has been found that the colony size of bacteria grown on an agar plate decreases with increasing agar gel concentration. Evidenc from recent studies suggests that the bacterial colony dynamics is closely related with the mechanical properties of the substrate. We investigate whether bacterial growth on the agar substrate is controlled mostly by the nutrients' diffusion which is hindered more in porous medium than in solution. The number of bacterial cells in single colonies is found to be inversely correlated with agar concentration. High-resolution live cell imaging at the single bacterium level confirms that the bacterial growth rate is reduced with increasing agar concentration. There is a strong correlation between the slowed diffusion and the reduced number of cells in a high concentration of agar medium.
13th International Symposium on Flow Visualization 참가기
Lee, Sang-Hyeok ;
Journal of the Korean Society of Visualization, volume 6, issue 2, 2008, Pages 51~52
DOI : 10.5407/JKSV.2008.6.2.051
Gas Dynamics 실험실
Kim, Hui-Dong ;
Journal of the Korean Society of Visualization, volume 6, issue 2, 2008, Pages 53~57
DOI : 10.5407/JKSV.2008.6.2.053