• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.99-105
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• 2017

This paper confirms the similarity of temperature tendency through numerical analysis and comparison with test, and it also confirms that temperature prediction of LED lightings is possible by numerical analysis. We confirmed that the temperature difference is about $10{\sim}20^{\circ}C$ except for some measurement points and shows similar tendency with the interpretation through manufacturing and performance analysis of AL heat sink applied Circular LED street lights and manufacturing and performance analysis of CMP-PLA heat sink applied Circular LED street lights. The simulations use Octree technique in SC/Tetra to set the grid size df the surface.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.4 s.54
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• pp.323-327
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• 2005

Although many studies have been performed to elucidate the molecular consequence of ultraviolet irradiation on an aging, little is known about the effect of natural products. Matrix metalloproteinases (MMPs) we known to play an important role in (a) photoaging. Hete we investigated the effect of $1,2,4,6-tetra-O-galloyl-{\beta}-{_D}-gluco- pyranose (1)$ and 3,4,5-trihydroxybenzoic acid (2) on the expression of MMP-1 in UVA-irradiated human skin fibroblasts (products), (on the) activity of MMP-1, and (on the) scavenging activities of free radicals. Compounds 1 and 2 were isolated from Melothria heterophylla (Cucurbitaceae). These compounds were found to scavenge free radicals and reactive oxygen species (ROS) and were measured to have the $SC_{50}$ values of $3.9{\mu}M\;and\;13.3{\mu}M$ against the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and $4.3{\mu}M\;and\; 4.0{\mu}M$ against superoxide radicals in the xanthine/xanthine oxidase system, respectively. Compounds 1 and 2 showed a dose-dependent inhibitory effect on the e):pression and activity of MMP-1 in the UVA-irradiated human skin fibroblasts. Therefore, we concluded that compounds 1 and 2 significantly inhibited MMP-1 expression at the protein level. Also, these compounds were determined to have a potent antioxidant activity. From these results, we suggest that these compounds nay be used as (a) new anti-aging agents for the photo-damaged skin.

• Journal of computational fluids engineering
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• v.13 no.4
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• pp.72-79
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• 2008

This study is to investigate the air flow around a sirocco fan which is used in a range hood. The main object of the study is to improve the flow rate of the fan by analysis of unsteady 3-dimensional incompressible flow. Overall analysis is carried out using CFD method. For this, we used a commercial code, SC/Tetra, and used a sliding mesh method to give the same condition as an actual state. First, verification of the CFD results is done by comparing the experimental data with the numerical data for the suction flow rate. It is confirmed that two results are well consistent. Then for the improvent of flow rate, the effect of shape factors such as diameter ratio of fan, geometry of case, cut-off aperture and guide angle of case exit on the suction flow rate was considered. Especially, for a new design of housing, the principle of Archimedes spiral was used. The overall analysis was applied to a new design of housing, and the result showed an increase of flow rate by 10.7%.

• Journal of Power System Engineering
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• v.16 no.3
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• pp.29-36
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• 2012

The computational flow analysis using LES technique was introduced to investigate the flow field improvement of an indoor RAC chassis consisting of a rear-guider, a stabilizer and a cross-flow fan. This unsteady three-dimensional numerical analysis was carried out by the commercial SC/Tetra software. The edge blocks were adopted in this study as a tool for the flow field improvement of an indoor RAC. In view of the results so far achieved, the edge blocks cause the center of an eccentric vortex to be stable along all length of a cross-flow fan, and then, the static pressure and the velocity vector show a stable distributions. In consequence, because the edge blocks eliminate a reverse flow near the edges, an exhausting flow becomes to be stable and uniform.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.183-190
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• 2009

The objective of this study is to get simulation data about pulsatile flow around an interior solid body inside a bifurcated tube. All the processes were based on CFD method, with a commercial FVM code, SC/Tetra ver. 6.0 for solving, and with CATIA R16 for generating geometries. The bifurcated tube models were drawn with the bifurcated angle of 45 degrees, considering Murray's law about the diameter ratio. With various locations of the object, the effects of flow on the drag were considered. For the pulsating flow condition, the velocity wave profile was given as the inlet boundary condition. To validate all the result, the simulation was compared with the existing data of the other papers first. Overall flow field of both data were similar, but there was some difference at a zero velocity. Therefore the next simulation was continued with the sine wave profiles where there is no negative flow, and then the data was compared with one of the pulmonary artery velocity where there is negative flow. The final process was to calculate flow variables such as the wall shear stress (WSS) and to compute the drag of the solid object.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.108-114
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• 2011

Steam reformer was organized with steam reforming process and CO removing process. The steam reforming process needed high temperature, 600~900 $^{\circ}C$, for catalytic-reaction which was extract of hydrogen from steam and hydrocarbon. The effects of the evaporator configuration on its heat transfer characteristics were investigated both experimentally and numerically to pursue the miniaturization. In this study, three configurations were considered where the different structures were tested; empty, embossing and mesh filled. For the comparison of heat transfer performance of shape evaporator disk, numerical analysis using SC-Tetra code and experiment were carried out. In case of reformer system design, it should be considered heat transfer rate, differential pressure and fluid flow direction.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.4
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• pp.370-377
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• 2018

Ball valve has been widely used in the field of high-pressure gas pipeline as an important component because of its low flow resistance and good leakage performance. The present paper focuses on the flow nature at the downstream of the ball valve used for gas pipelines according to valve opening rates. Steady 3-D RANS equations, SC/Tetra, have been introduced to analyze the flow characteristics inside the ball valve. Numerical boundary conditions at the inlet and outlet of the valve system are imposed by mass flow-rate and pressure, respectively. Velocity distributions obtained by numerical simulation are compared with respect to the valve opening rates of 30, 50, and 70%. Cavity distributions, asymmetry flow velocity and the flow stabilization point at each opening rate are also compared. When the valve opening rates are 30 and 50%, the flow stabilization requires the sufficient length of 10D or more due to the influence of the recirculation flow at the downstream of the valve.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.159-165
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• 2008

A sirocco fan is widely used for discharging pollutants of a kitchen space since it is able to generate a relatively high air flow rate considering its small size and makes less noise than a axial fan or a centrifugal fan. However, it has a problem because its efficiency is low, and power consumption is larger. Performance of a sirocco fan is influenced by various factors such as number of the fan blades, diameter of the fan, geometry of the fan, geometry of its housing, revolution frequency, static pressure condition, and etc. This research investigated the effect on the performance of geometry of the housing. For CFD analysis, we used a commercial code, SC/Tetra, and used a sliding mesh method to give the same condition as an actual state. Verification of the CFD results is done by comparison of experimental data and numerical one about the suction flow rate, and it is confirmed that two results are well consistent. After we changed the shape of housing according to Archimedes' screw, we observed that suction efficiency is improved by 10.7% maximum.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.522-525
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• 2008

A vacuum cleaner is the widely used home equipment. However, it has a trouble with too much power consumption. Most losses occur at the centrifugal fan. To remedy this trouble the investigation of motor, which is the main component of vacuum cleaner, is required. The flow characteristics around the high-speed rotating centrifugal fan which is influenced by the very low inlet pressure is quite different from a commonly used fan. Hence it is quite difficult to analyze the flow by the experimental means or by the numerical simulation. In this research, it is aimed to improve the air-suction performance of a vacuum cleaner through the flow analysis around a motor. The efficiency of the centrifugal fan is affected by blade shape, blade number, blade pitch, etc. The influence of the shape of impeller on the flow is investigated in this study. The flow around the centrifugal fan is simulated by applying the moving mesh. To verify the validity of the computation results, the air flow rate and the pressure field to the cleaner is compared with the experimental data. All simulations are performed by using commercial code SC/Tetra. The calculated results show good agreement with the experimental ones and it is believed to be promising to use computational simulation in the improvement of the vacuum cleaner performance.

• Journal of Power System Engineering
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• v.16 no.4
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• pp.51-59
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• 2012

The computational flow analysis using LES technique was carried out to investigate the flow characteristics of a sirocco fan under the maximum flowrate condition. The commercial SC/Tetra software was used for this unsteady and three-dimensional numerical analysis. In consequence, because a flow is unstable within the range of about 50% of a housing depth from a bellmouth around the cutoff region, the passing flow through the blade cascade occurred on the X-Y plane is a slow or a reverse with approaching to the housing inlet. Also, the secondary flow shows on the radial plane of a housing, and its vortex center exists within about 33% of a housing depth from a bellmouth except the cutoff region. Moreover, the flow occurring on the exit plane of a sirocco fan shows a complex secondary flow.