• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2512-2517
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• 2007

Effect of natural convention for hot plate surface temperature uniformity was studied by experiments that were adjusted height of chamber and temperature difference. The hot plate chamber is composed of the hot plate and the upper heater and adiabatic vertical wall. The hot plate diameter is 220mm and maintains temperature at $150^{\circ}C$. Flow pattern compares with surface temperature and confirms that natural convection affects on temperature uniformity of hot plate surface. In case, temperature non-uniformity of hot plate surface is due to heater pattern, lots of weak and small flow cells more improve temperature uniformity than stronger flow cells or non-developing flow cell. Improve temperature uniformity $1.2^{\circ}C$ when developing weak and small flow cells.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.10
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• pp.819-825
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• 2006

In a SOFC/GT (solid oxide fuel cell/gas turbine) hybrid power generation system, the recuperator is an indispensible component to enhance system performance. Since the expansion ratio to the recuperator core is very large, generally, the effective header design to distribute the flow uniformly before entering the core is crucial to guarantee the required performance. In the present study, we focus on the design of a diffuser type recuperator header with a 90 degree turn inlet port. To reduce the flow separation and recirculation flows, multiple horizontal vanes are used. The number of horizontal vanes is varied from 0 to 24. The air flow velocity is measured at 40 points just behind the core outlet by using a hot wire anemometer. Then, the flow non-uniformity is evaluated from the measured flow velocity. The experimental results showed that inlet air velocity did not effect on relative flow non-uniformity. According to increasing the number of horizontal vanes, flow non-uniformity reduced about $40{\sim}50%$ than without using horizontal vanes.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2153-2155
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• 2005

SF6 &NF3 chemistry를 사용하여 W bitline process 조건에서 plasma confinement 및 gas & radical의 flow에 영향을 미치는 focus ring 재질과 두께변경을 하여 Rnit non uniformity 평가한다.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.48-51
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• 2004

Chemical Mechanical Polishing(CMP) is popularly used in production of semiconductor because of large area polishing ability probability of improvement for more integrated circuit. However, present CMP processing causes some non-uniformity errors which can be critical for highly integrated circuit. Previous studies predict that flow-field of slurry during CMP can create non-uniformity, but no quantitative measurement has conducted. In this study, using PIV, slurry velocity flow-field during CMP is measured by changing the ratio of RPM of pad and carrier with tuned PIV system adequate for small room in CMP machine and Cabot's non-groove pad Epad-A100. The result show that velocity of slurry is majorly determined by pad-rpm and the ratio of between carrier and pad rpm make some changes in streamlines.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.55-65
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• 1998

A numerical and experimental study of three-dimensional steady incompressible non-reacting flow inside various dual-monolith catalytic converters has been conducted for achievement of performance improvement, reduction of light-off time and longer service life by improving the flow uniformity within the monolith. In this study, the effects of curvature of inlet exhaust pipe and monolith brick length on the flow uniformity and pressure drop within monolith were numerically investigated. The computations are confirmed by measurements of steady flow. The agreement between computations and experiment was relatively good. The result of this study shows that curvature of inlet exhaust pipe and monolith brick length gave a great effect on the flow uniformity and the shorter the brick length, the lower flow uniformity and the less pressure drop.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.1147-1150
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• 2003

When a braun tube becomes wider, one of the major problems to be experienced is the non-uniform coating along the four diagonal directions on its surface. This non-uniformity in the coating thickness has a deep relation with the fluid flow on the surface of a braun tube. In order to control the fluid flow properly, we install the plate to block fluid flow at the corner of a braun tube. In the present study, we investigate the effects of the geometry of plate to control the fluid flow and coating uniformity and determine the optimal shape of plate to improve the quality of coating uniformity.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.4
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• pp.72-79
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• 1996

The recent trend of higher output engines with more auxiliary parts is resulting in greater heat generation in the engine compartment. In order to maximize the heat dissipation and eliminate the inefficient flow in the engine compartment, it is necessary to understand the flow field under the hood. In this respect, experimental study as well as numerical analysis should be conducted. The automated measuring system was constructed to obtain three dimensional mean flow data with high accuracy. The measurements have been made on a vehicle with a steady incoming air flow. The result shows that there exists a high degree of non-uniformity in the mean flow velocity at the front of radiator.

• Journal of computational fluids engineering
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• v.9 no.4
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• pp.13-19
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• 2004

Flow distribution of a mid-size vehicle in engine room was investigated numerically to analyze the flow performance of given design cases in a front body of the mid-size vehicle. The data analyzed are the mass flow rate at the upper and lower openings, in the radiator, and the degree of non-uniformity of the velocity field at the inlet of the radiator. It is presented that the shape of the front end and the presence of the undercover greatly affect the flow fields, therefore, the flow performance.

• Journal of the Korean institute of surface engineering
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• v.23 no.3
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• pp.160-166
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• 1990

The effects of the variation of proedd varibles on the flow patterns and effects of the flow patterns on the deposition rate and uniformity in the Si-epitaxy CVD with SiH4 as the source of Si were studied through the calculation by use of control volume method. The reslts showed that the natural convection was undesirable to the uniformity of deposition rate, whose effects were decreased with the dercrese with the decrese of the pressure in the reactoor and with the increase of the flow rate. However. the excessive increase of flow rate caused the movement of the unreacted gas to the substrate. Therefore it resulted in the non-uniform depositions. The rotation of substrate was apperared to improve the uniformity. The resulte of this study could used in CVD process to design the reator and to find the optimum conditions of the process variables.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.19-25
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• 2023

With an attempt to investigate the correlation between the internal pressure distribution of slit nozzle and the thickness uniformity of slot-coated thin films, we have performed computational fluid dynamics (CFD) simulations of slit nozzles and slot coating of high-viscosity (4,800 cPs) polydimethylsiloxane (PDMS) using a gantry slot-die coater. We have calculated the coefficient of variation (CV) to quantify the pressure and velocity distributions inside the slit nozzle and the thickness non-uniformity of slot-coated PDMS films. The pressure distribution inside the cavity and the velocity distribution at the outlet are analyzed by varying the shim thickness and flow rate. We have shown that the cavity pressure uniformity and film thickness uniformity are enhanced by reducing the shim thickness. It is addressed that the CV value of the cavity pressure that can ensure the thickness non-uniformity of less than 5% is equal to and less than 1%, which is achievable with the shim thickness of 150 ㎛. It is also found that as the flow rate increases, the average cavity pressure is increased with the CV value of the pressure unchanged and the maximum coating speed is increased. As the shim thickness is reduced, however, the maximum coating speed and flow rate decrease. The highly uniform PDMS films shows the tensile strain as high as 180%, which can be used as a stretchable substrate.