• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1528-1534
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• 2004

The combination of ultrasound echo images with digital particle image velocimetry (DPIV) methods has resulted in a two-dimensional, two-component velocity field measurement technique appropriate for opaque flow conditions including blood flow in clinical applications. Advanced PIV processing algorithms including an iterative scheme and window offsetting were used to increase spatial resolution. The optimum concentration of the ultrasound contrast agent used for seeding was explored. Velocity validation tests in fully developed laminar pipe flow result of echo PIV showed good agreement with both optical PIV measurements and the known analytic solution based on a volume flow measurement.

• Journal of the Korean Society of Visualization
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• v.9 no.3
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• pp.24-29
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• 2011

The improvement of climatic comfort is crucial not only for passenger comfort but also for driving safety. Therefore, a better understanding on the flow characteristics of ventilation flow inside the passenger compartment is essential. Most of the previous studies investigated the ventilation flow using Computational Fluid Dynamics (CFD) calculations or scale-down water-model experiments. In this study, the ventilation flow inside the passenger compartment of a real commercial automobile was investigated using a Particle Image Velocimetry (PIV) velocity field measurement technique. Under real operating conditions, the velocity fields were measured at several vertical planes for several ventilation modes. The experimental data obtained from this study can be used to understand the detailed flow characteristics in the passenger compartment of a real car and to validate numerical predictions.

• Journal of the Korean Society of Visualization
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• v.9 no.3
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• pp.16-23
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• 2011

Experiment and numerical investigation are performed on swirling water flow in a vertical circular tube. This kind of flow is used in heat exchangers, combustion chambers, thermal power plants, and other mechanical equipment to move slurries or to convey materials. However, limited information on swirling flow in vertical circular tubes is available. In the current paper, the three-dimensional particle image velocimetry(PIV) technique is employed to compare the measured velocity profiles of water along the vertical circular tube with those of non-swirl flow. In addition, computational fluid dynamics(CFD) code was applied to calculation of the flow velocities with swirl.

• Journal of Korea Water Resources Association
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• v.34 no.4
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• pp.327-333
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• 2001

Particle tracking velocimetry (PTV) is introduced and applied to the fall-velocity measurement. The fall velocities of sediment particles were measured using PTV in the still water and compared with the values presented in the existing literature. Comparison shows that PTV measures the fall velocities accurately. This result enables the measurement of fall velocity in the turbulent flows, which was not possible with conventional methods.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.1-10
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• 2002

As the preliminary stage for the countermeasure of thermal loading in miller cycle engine, coolant flows in the cylinder head of base engine including exhaust valve bridge were visualized and analyzed by using PIV technique. It was found that low coolant velocity regions were around exhaust valve bridge, around which stagnation of the coolant flow was observed due to the complex geometry configuration of water jacket. And velocity variation between each cylinder was remarkable. For the countermeasure of these, it is necessary to enhance coolant flow around exhaust valve bridge and to improve the deviation of coolant flow between each cylinder.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.3
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• pp.260-274
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• 2005

An experimental investigation was performed to study the characteristics of turbulent swirling flow in the cylindrical annuli. The swirl angle measurements were performed by flow visualization technique using smoke and dye liquid. By using the particle image velocimetry method. this study has found the time-mean velocity distribution and turbulent intensity with swirl for Re=20,000. 30.000. 50.000. and 70,000 along longitudinal sections. The results appear to be physically reasonable. Other experimental study was performed to investigate heat transfer characteristics of turbulent swirling air flow in axisymmetric annuli. The static pressure. the local air flow temperature, and the wall temperature with decaying swirl were measured by using thermocouples and the friction factor and the local Nusselt number were calculated for Re=30,000. 50,000 and 70000. The local Nusselt number was compared with that obtained from the Dittus-Boelter equation with swirl and without swirl, respectively. The results showed that the swirl enhances the heat transfer at the inlet and the outlet of the test tube.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.4
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• pp.417-425
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• 2005

An experimental study is performed on the turbulent swirling flow behind a crcular cylinder using 2-D PIV technique. The Reynolds numbers investigated are 10.000, 15,000. 20.000 and 25.000. The mean velocity vector, time mean axial velocity, turbulence intensity, kinetic energy and Reynolds shear stress behind the cylinder are measured before and behind the cylinder along the test tube. A comparison is included without swirling flow behind a circular and square cylinder. The recirculation zones are shown unsymmetric profiles.

• 한국가시화정보학회:학술대회논문집
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• 2006.12a
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• pp.63-67
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• 2006

Spray characteristics of an injector employed in mono-propellant hydrazine thrusters were investigated by PIV(particle image velocimetry) and PDA(phase Doppler anemometry) techniques. The instantaneous plane images captured by PIV measurement were examined in order to judge the pass-fail criteria of spray injection performance according to the specific pressure supplied. PDA technique was also applied to measure the velocity and droplet size of spray which were not obtainable by PIV measurement. The objective of this experimental study is the evaluation of the injector performance which may be utilized for the design of brand-new injector through the clear understanding of spray characteristics.

• 한국가시화정보학회:학술대회논문집
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• 2006.12a
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• pp.55-58
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• 2006

The flow characteristics in a confined slot jet impinging on a flat plate were investigated by using cinematic Particle Image Velocimetry technique. The three different kinds of confined slot were applied to the jet with a view to evaluating the shape effect and the jet Reynolds number was varied from 250 to 1000 for a fixed jet-to-plate spacing of H/W=5. It was found that the vortex structures in the shear layer are developed with increase of Reynolds number and that the jet becomes unsteady by the interaction of vortex pairs between 500 and 750 of Reynolds number. Finally, the slot shape was proved to be related with the generation timing of vortex pair and the temporal vortex structure.

• Journal of the Korean Society of Visualization
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• v.6 no.1
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• pp.34-40
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• 2008

The flow characteristics in a confined slot jet impinging on a flat plate were investigated in low Reynolds number regime (Re$\leq$1,000) by using time-resolved particle image velocimetry technique. The jet Reynolds number was varied from 404 to 1026, where it is presumed that the transient regime exists. It is found that the vortical structures in the shear layer are developed with increasing Reynolds number and that the jet remains steady at the Reynolds number of 404. Vortical structures and their temporal evolution are verified and the results were compared with previous numerical studies.