• 순환기질환의공학회:학술대회논문집
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• 2006.10a
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• pp.19-20
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• 2006

• Proceedings of the Optical Society of Korea Conference
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• 1998.08a
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• pp.86-87
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• 1998

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.690-695
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• 2001

The three-dimensional spatial structures of impeller flow created by a six bladed Rushton turbine have identified based on the volumetric velocity information from multi-plane stereoscopic PIV measurements. A total of 10 planes with 2 mm space with a 50 mm by 64 mm size of the field of view were targeted. To reduce the depth of focus, we adopted an angle offset configuration which satisfied the Scheimpflug condition. The distortion compensation procedure was utilized during the in situ calibration. Phase-locked instantaneous data were ensemble averaged and interpolated in order to obtain mean 3-D, volumetric velocity fields on a 60 degree sector of a cylindrical ring volume enclosing the turbine blade. Using the equi-vorticity surface rendering, the spatial structure of the trailing vortices was clearly demonstrated. Detail flow characteristics of the radial jet reported in previous studies of mixer flows were easily identified.

• Korea-Australia Rheology Journal
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• v.13 no.2
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• pp.97-106
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• 2001

Three-dimensional flow analysis was performed by using the control volume finite-element method for design of a profile extrusion die. Because polymer melt behavior is complicated and cross-sectional shape of the profile extrusion die is changing continuously, the fluid flow within the die must be analyzed three-dimensionally. A commercially available polypropylene is used for theoretical and experimental investigations. Material properties are assumed to be constant except for the viscosity. The 5-constant modified Cross model is used for the numerical analysis. A test problem is examined in order to verify the accuracy of the numerical method. Simulations are performed for conditions of three different screw speeds and three different die temperatures. Predicted pressure distribution is compared with the experimental measurements and the results of the previous two-dimensional study. The computational results obtained by using three dimensional CVFEM agree with the experimental measurements and are more accurate than those obtained by using the two-dimensional cross-sectional method. The velocity profiles and the temperature distributions within several cross-sections of the die are given as contour plots.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.8
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• pp.619-626
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• 2017

In this work, the effect of attitude angle variation on drag coefficients of hemisphere in a Mach 6 flow has been investigated. Experiments were conducted in a shock tunnel and a free-falling technique was used to minimize flow disturbance by a sting. For attitude and drag coefficient measurements of a free-falling hemisphere, a free-falling technique based on a releasing mechanism with a stair-typed module and an electromagnet was developed. A shadowgraph technique was used for flow visualization using a high-speed camera.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.4
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• pp.469-477
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• 2013

In order to investigate the influence of feed water inequity on the settling performance for parallel arranged upflow sedimentation basin in domestic G_WTP(Water Treatment Plant), CFD(Computational Fluid Dynamics) simulation were employed and ADV(Acoustic Doppler Velocimeter) measurements were carried out. From the results of both CFD simulations and ADV measurements, the differences among inlet flow rates to each inlet structure make turbulent energy dissipation uneven overall sedimentation basin. Especially local velocities in the near of both side wall were observed over the design overflow rate(74.4 mm/min). Also, it was confirmed that this inequity of inlet flow would exert an serious influence on the turbidity of settled water which is out from 8 troughs. Even though experimental velocities in full scale basin about 20% higher than the simulated, the results of ADV measurement were in good accordance with those of CFD simulations.

• Journal of ILASS-Korea
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• v.12 no.2
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• pp.115-122
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• 2007

The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomize. internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD (Sauter Mean Diameters) distribution by using Planar Liquid Laser Induced Fluorescence technique. The objectives of this research are get a droplet distributions and drop size measurements of each condition and compare with the other flow effects. As the result, This research has been showned that droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects, and normalized distance from the injector exit length(x/d, y/d). There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.9
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• pp.1015-1021
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• 2004

Micro-resolution Particle Image Velocimetry(Micro-PIV) was used to measure the flow in a micro-branch(Micro-Bypass). In this paper, effects of particle lump at the tip of a Micro-branch and difficulties of Micro-PIV measurements for microfluidics with branch passage were described. Micro-bypass was composed of a straight channel(200(100)${\mu}$m width ${\times}$ 80${\mu}$m height) and two branches which has 100(50)${\mu}$m width ${\times}$ 80${\mu}$m height. One of branches was straight and the other was curved. Experiments were performed at three regions along streamwise direction(entrance, middle and exit of branch) and five planes along vertical direction (0, ${\pm}$10, ${\pm}$20 ${\mu}$m) for the range of Re=0.24, 1.2, 2.4. Numerical simulation was done to compare with the measurements and understand the effects of particle lump at the tip of branch. And another fluid(3% poly vinyl Alcohol aqueous solution) were adapted for this study, so there were no particle sticking. In this case, we could get velocity difference between straight and curved branches.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.533-536
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• 2002

A heating flow discharged from a 4-way ceiling type indoor unit has been investigated using a PIV(particle image velocimetry) system For the PIV measurements, an experimental model of 1/10 scale with a transparent room was devised by satisfying the Archimedes number, which is generally used in case that the forced convection has the similar magnitude as the natural convection. To optimize the heating flow, several vane angles and vane control algorithms of cross and right angle controls were considered. Regarding the vane angle, the experimental results show that it should be less than $30^{\circ}$ to avoid re-suction flows which decrease the performance of the air-conditioner. At the vane angle of $30^{\circ}$, applying open/close control gives nae to more uniform distribution of the heating flow than without control. Especially, the cross-control seems to be satisfactory for the thermal comfort.

• Journal of Environmental Impact Assessment
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• v.5 no.1
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• pp.31-45
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• 1996

This paper presents the results from a hydrodynamic model study to predict the impacts of coastal reclamation in Pusan harbor system using RMA2 which is a tidal flow model of the US Army Corps of Engineers' TABS-2 system. A finite element mesh was constructed and refined to cover the complicated geometry of Pusan harbor system and the proposed reclamation area. The model was calibrated to tidal elevations and currents measured during spring fall syzygys. Under the three different tidal conditions including summer winter syzygys, spring fall quarters, and summer winter quarters, the model predictions were compared with the field measurements both in tidal elevation and current. In all cases, there were excellent agreements between the model predictions and the field measurements. The validated model was then used to predict the changes in tidal current and elevation that might occur due to the coastal reclamation. It was predicted that there would be no change in tidal elevation of this system after the reclamation. In tidal current, however, discernible changes were predicted near the proposed reclamation area both in magnitude and direction.