• Food Science and Preservation
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• v.20 no.3
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• pp.289-295
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• 2013

The capacity of a pressure fan can be designed based on the air flow resistance of containers packed with fruits and vegetables in a pressure cooling system. This study was conducted to develop an air flow resistance model that was dependent on changes in the air flow rate and the method of stacking containers. The air flow resistance of a container packed with uniformly shaped balls was 1.5 times greater than the sum of the air flow resistance of a vacant container and that of a wire net container packed with only balls. In addition, the air flow resistance increased exponentially as the width of the stacks increased; however, the air flow resistance did not increase greatly as the length and height of the stacks increased, which indicates that the air flow resistance is primarily influenced by the width of the stack in the air flow direction. The air flow resistance in two lines of stacking was up to 17% less than that of the width of the stack. It was also possible to determine the air flow resistance using a function of the air flow resistance through a single container and develop a prediction model. A prediction model of air flow resistance that is dependent on the stacking method and the air flow resistance of a single container was developed.

• Journal of the Semiconductor & Display Technology
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• v.23 no.2
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• pp.114-122
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• 2024

NF₃, Chamber cleaning gas, has a high Global Warming Potential (GWP) of 17,000, causing significant greenhouse effects. Reducing gas usage during the cleaning process is crucial while increasing the cleaning Rate and reducing cleaning standard deviation (Stdev). In a previous study with a 6-inch PECVD chamber, a multiple linear regression analysis showed that Power and Pressure had no significant effect on the cleaning Rate because of their P-values of 0.42 and 0.68. The weight for Flow is 11.55, and the weights for Power and Pressure are 1.4 and 0.7. Due to the limitations of the research equipment, which differed from those used in actual industrial settings, it was challenging to assess the effects in actual industrial environment. Therefore, to show an actual industrial environment, we conducted the cleaning process on a 12-inch PECVD chamber, which is production-level equipment, and quantitatively analyzed the effects of each variable. Power, Pressure, and NF3 Flow all had P-values close to 0, indicating strong statistical significance. The weight for Flow is 15.68, and the weights for Power and Pressure are 4.45 and 5.24, respectively, showing effects 3 and 7 times greater than those with the 6-inch equipment on the cleaning rate. Additionally, we analyzed the cleaning Stdev and derived that there is a trade-off between increasing the cleaning Rate and reducing the cleaning Stdev.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.45-47
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• 2005

We have investigated the mixing behavior of a tubular heat exchanger reactor using CFD and compared its mixing performance with different type of reactors such as jet mixer and continuous stirred tank reactor (CSTR). The mixedness in each reactor was quantified introducing a statistical average value, the coefficient of variation (CoV), which is a normalized standard deviation of concentration of a component over the whole fluid domain. Through the analysis of the flow pattern and turbulent energy distribution, we suggested a simple but effective way to improve the mixing performance of the tubular heat-exchanger reactor, which include the addition of the internals and/or the increase of the recycle flow rate. It was found that the CoV value of the tubular reactor could be nearly equivalent to that of CSTR by applying those two alternatives suggested here.

• Korea-Australia Rheology Journal
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• v.21 no.4
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• pp.289-297
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• 2009

We numerically analyzed flow characteristics of the polymer melt in the screw equipment using a proper modeling and investigated design parameters which have influence on the mixing performance as the capability of the screw equipment. We considered the non-Newtonian and non-isothermal flow in a single rotor equipment to investigate the mixing performance with respect to screw dimensions as shape parameter of the single rotor equipment and screw speed as process parameter. We used Bird-Carreau-Yasuda model as a viscous model of the polymer melt and the particle tracking method to investigate the mixing performance in the screw equipment and considered four mixing performance indexes: residence time distribution, deformation rate, total strain and particle standard deviation as a new mixing performance index. We compared these indexes to determine design parameters and object function. On basis of the analysis results, we carried out the optimal design by using the response surface method and design of experiments. In conclusion, the differences of results between the optimal value and numerical analysis are about 5.0%.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.315-318
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• 1995

The optimum design problem of a coat-hanger die is solved by the inverse formulation. The flow in the die is analyzed using three-dimensional model. The new model for the manifold geometry is developed for the inverse formulation. The inverse problem for the optimum die geometry is formed as the optimization problem whose objective function is the linear combination of the square sum of pressure gradient deviation at die exit and the penalty function relating to the measure of non-smoothness of solution. From the several iterative solutions of the optimization problem, the optimum solution can be obtained automatically while producing the uniform flow rate distribution at die exit.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.392-397
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• 2000

Mono-disperse particles generated by a condensation particle generator are widely used to meet the experimental and industrial needs. The characteristics of particles generated by homogeneous nucleation have been studied experimentally using a laminar flow condensation particle generator. Dry nitrogen gas saturated with oleic acid vapor was cooled well below the saturation temperature causing the highly supersaturated vapor to nucleate. The dependence of GSD(Geometric Standard Deviation), GMD(Geometric Mean Diameter), and the mass concentration of particles on the temperature at the evaporator, flow rate and the temperature condition at condenser was studied. The experimental results show that the mass concentration of particles is affected by the radial temperature profile at condenser. Nucleation at the center of the condenser causes the mass concentration of particles to increase. The experimental results also show that the suppression of additional nucleation by a constant temperature condition at the condenser increases the mean diameter of particle.

• Analytical Science and Technology
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• v.8 no.4
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• pp.843-848
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• 1995

A sensitive method for the determination of trace amounts of phosphate by fluorescence-quenching detection / FIA is proposed. The fluorescence of Rhodamine B(RB) was quenched with the formation of the ion associate of molybdophosphate with RB;${\lambda}_{ex}$ and ${\lambda}_{em}$ were 560nm and 580nm, respectively. A calibration graph was linear over the ranges from $10^{-8}$ to $3{\times}10^{-6}M$ of phosphate (~0.3~93ppb of phosphorus). The relative standard deviation was 1.2% with $8{\times}10^{-7}M$ phosphate solution and sampling rate was 15 samples / h. The proposed method was applied to the determination of phosphate in sea and river water samples.

• Journal of the Semiconductor & Display Technology
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• v.15 no.2
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• pp.70-73
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• 2016

Previously proposed contamination detecting sensor was revisited for the investigation of the liquid tendency. Experiments revealed different output voltages for several kinds of liquid input, but showed same values for various flow rates of each liquid. The transmittance of the liquid was measured, and it is well correlated with the voltages. Linearity in values and the compensation of the sensor to sensor deviation were tried to obtain. And, long term test was performed as attached at the manufacturing equipment in the field.

• Journal of the Korean Magnetics Society
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• v.26 no.4
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• pp.142-148
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• 2016

To evaluate the effect of flip angle on flow rate measurements obtained with phase contrast MRI according to the flip angle degree in ascending aorta and velocity encoding (VENC) was (150 m/s). 1.5T MRI in patients 17 (female: 8, male: 9, mean age $57.9{\pm}15.4$) as a target by applying a non-breath holding techniques to flip angle VENC (150 cm/s) in each of the ascending aorta was measured by changing $20^{\circ}$, $30^{\circ}$ and $40^{\circ}$. Blood was obtained a peak velocity, average velocity, net forward volume, net forward volume/body surface area. Ascending aorta from average velocity (AV) measured the average value of the flip angle $20^{\circ}$ (9.87 cm/s), $30^{\circ}$ (9.6 cm/s) and $40^{\circ}$ (10.05 cm/s). Blood flow VENC in was blood flow change in flip angle change was high most blood flow measurement when the flip angle $30^{\circ}$ in VENC, crouching each blood flow is also proportional to the increases in the $20^{\circ}$ to $40^{\circ}$ and was increased, the deviation of the peak velocity and the average velocity is the smallest deviation from the flip angle $30^{\circ}$. Flip angle $20^{\circ}$, $30^{\circ}$ and $40^{\circ}$ in peak velocity, average velocity, net forward volume, net forward volume/body surface area was no statistically significant difference (p > .05). Blood flow velocity and blood flow is measured by applying to adjust the flip angle accurately calculate the blood flow is important information for diagnosis and treatment of cardiovascular diseases, and can help in the examination on the blood flow measurement.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1042-1046
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• 2008

Both the weighing bridge and the diverter system is a important component in achieving a high accuracy liquid flow rate standard using a static gravimetric method. The weighing bridge is a tank which weighing collected flow with a load cells. The diverter is a moving device used to direct flow alternately along its normal course(by pass) or towards the weighing tank. The time needed for collection into the weighing tank is measured using a timer. So it is important to the diversion period is sufficiently fast and triggering point of timer which is determined the filling time. On this studies show that the measurement deviation of load cell and uncertainty of diverter system for changing diversion speed and triggering point was estimated in accordance with Guide to The Expression of Uncertainty in Measurement(ISO).