• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.426-435
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• 2012

The variation of stream flow is the one of the most important factors which influence on that of water quality in the unit watershed. The target water quality goal is established and permissible load is allotted in the base of the standard flow condition along with its water quality for the management of Total Maximum Daily Loads (TMDLs). A standard flow selected could cause problems in the load allotment if it was not properly arranged. This study reviewed the acquisition of water quality data, the self-variation and the retainability in water quality on the specific flow conditions. This study also proposed the median and the adjusted average flow condition out of general flow conditions as alternative standard flow conditions. It is considered that the alternatives can make the water quality data easily acquired and the water quality representativeness more enhanced on the standard flow conditions.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.88-91
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• 2004

The multiphase flow simulator, MPS, is developed based on the fractional flow approach considering tile fully three phase flow with general initial and boundary condition. Most existing fractional flow-based models are limited to two-phase flow and specific boundary conditions. Although there appears a number of three-phase flow models, they were mostly developed using pressure based approaches. As a result, these models require cumbersome variable-switch techniques to deal with phase appearance and disappearance. The use of fractional flow based approach in MPS makes it unnecessary to use variable-switch to handle the change of phase configurations. Also most existing fractional flow based models consider only specific boundary conditions. However, the present model considers general boundary conditions of most possible and plausible cases which consists of ten cases.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.59-60
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• 2006

Some useful flow regime data are obtained from the experiments using the flight producing hyper-gravity(2g) conditions and on ground(1g) with the identical flow conditions. The flow regime data obtained at 1g and 2g conditions are compared with new dimensionless flow regime map using Fr, Bo and We number related with gravity, surface tension and inertia force.

• Journal of computational fluids engineering
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• v.13 no.1
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• pp.21-27
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• 2008

A numerical study for laminar flow in the entrance region of helical tubes for uniform inlet velocity conditions is carried out by means of the finite volume method to investigate the effects of Reynolds number, pitch and curvature ratio on the flow development. This results cover a curvature ratio range of 1/10$\sim$1/320, a pitch range of 0.0$\sim$3.2, and a Reynolds number range of 125$\sim$2000. It has been found that the curvature ratio does significantly effect on the angle of flow development, but the pitch and Reynolds number do not. The characteristic angle $\phi_c(=\phi/\sqrt{\delta})$, or the non-dimensional length $\overline{l}(=l\sqrt{\delta}cos(atan\lambda)/d)$ can be used to represent the flow development for uniform inlet velocity conditions. In uniform inlet velocity conditions, the growth of boundary layer delays the flow development attributed to centrifugal force, and in which conditions the amplitude of flow oscillations is smaller than that in parabolic inlet velocity conditions. If the pitch increases or if the curvature ratio or Reynolds number decreases, the minimum friction factor and the fully developed average friction factor normalized with the friction factor of a straight tube and the flow oscillations decrease.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.9
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• pp.791-801
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• 2000

An experimental study was conducted to analyze the effects of oil on refrigerant flow through adiabatic capillary tubes, and to develop a model for mass flow rates of refrigerant/oil mixture at various capillary tubes and flow conditions. Mass flow rates and the profiles of the pressures and temperatures along the capillary tubes was obtained with the oil concentration of R-22/SUNISO 4GS oil mixture at various test conditions. The flow trends as a function of geometry and flow conditions for pure refrigerant and refrigerant/oil mixture were similar in adiabatic capillary tubes. Mass flow rate of the refrigerant/oil mixture was less than that of pure refrigerant at the same test conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.1
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• pp.34-41
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• 1991

The effect of flow conditions on flow measurement is difficult to identify from the inherent characteristics of the flowmeters and flow standard system. A new experimental approach has been attempted to detect the turbine meter error due to inlet flow conditions. In this try not only the design of the turbine meter package but also the data analysis method was altered. It was found that k factor slope of the turbine meter responds to the change of flow conditions in the test line with higher sensitivity than the degree of the data scattering. The flow standard system of $0.1m^3/s$ was chosen for the investigation. The systematic and random error of the system were less than ${\pm}0.08%$ and ${\pm}0.13%$ respectively.

• Korean Journal of Hydrosciences
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• v.6
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• pp.23-37
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• 1995

In this experimental paper, the maximum scour depth at pier was student. The model of the pier of San Gye bridge in the Bocheong stream was set for the experimental studies. Several model verification processes were conducted through the roughness comparisons between model and prototype, pursuing scour depth variations with time depending upon channel bed variation, the comparison of the ratios between falling velocities and shear velocities in the model and prototype, and the comparison of pier scour depths between experimental data and field measuring data. The experiments were conducted in the free flow conditions and pressure flow conditions. The maximum scour depth at piers in the pressure flow conditions is almost twice as much as compared to the free flow conditions. Also, the maximum scour depth variations are indicated in the figures based on the Froude numbers, opening ratios, water depths and approaching angles in the free surface flow conditions.

• Journal of the Semiconductor & Display Technology
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• v.21 no.1
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• pp.33-38
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• 2022

This study investigates the outlet temperature of coolant heater based on heat and flow volume conditions. Through computer simulation, the coolant temperature at the outlet was analyzed to investigate the heat and flow volume conditions of the coolant heater, and the optimal conditions were derived. Results show that heat and flow volume conditions, it was confirmed that heat condition is 0.424 W/mm³, and flow volume condition is 500 l/h, demonstrates optimal conditions. The results of this study can be utilized to efficiently control the coolant temperature through various heat and flow volume conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.4
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• pp.533-539
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• 2001

In this study, results from an experimental and numerical study of flow distribution in a close-coupled catalytic converter (CCC) are presented. The experiments were carried out using a glow measurement system. Flow distribution at the exit of the first monolith in the CCC was measured using a pitot tube under steady and transient flow conditions. Numerical analysis was done using a CF D code at the same test conditions, and the results were compared with the experimental results. Experimental results showed that the uniformity index of exhaust gas velocity decreases as Reynolds number increases. Under the steady flow conditions, flow through each exhaust pipe concentrates on a small region of the monolith. Under the transient flow conditions, flow through each exhaust pipe with the engine firing order interacts with each other to spread the flow over the monolith face. The numerical analysis results support the experimental results, and help explain the flow pattern in the entry region of the CCC.

• Journal of ILASS-Korea
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• v.11 no.4
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• pp.212-219
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• 2006

The initial film flow development of the high-pressure swirl spray was investigated at different injector operating conditions to analyze film flow development and to provide the input data for the modeling works. This result can be also useful to verify the previously simulated results. The initial flow conditions such as liquid film thickness, flow angle and flow divergence are obtained by visualizing the inside and near the nozzle flow with a microscopic imaging system. The visualized images are quantified using an image processing tool. From the information of liquid film thickness and flow angle, the initial axial and tangential velocity and the swirl number of the swirl spray are successfully determined at various operating conditions. The experimental results showed that the initial liquid film thickness, flow angle and flow divergence are remained constant when the injection pressure is increased. However, initial film conditions are severely changed when the fuel temperature is increased. The swirl number remained constant when the injection pressure is increased while it showed increased value at high fuel temperature condition.