• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.4
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• pp.458-465
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• 2003

The main objective of the research is to develop a research code solving transient incompressible Navier-Stokes equation. In this research code, Adams-Bashforth method was applied to the convective terms of the navier stokes equation and the splitted equations were discretized spatially by finite element methods to solve the complex geometry problems easily. To reduce the divergence on the boundaries of pressure poisson equation due to the unsuitable pressure boundary conditions, multi step approximation pressure boundary conditions derived from the boundary linear momentum equations were used. Simulations of Lid Driven Flow and Flow over Cylinder were conducted to prove the accuracy by means of the comparison with results of the previous workers.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.2
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• pp.103-114
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• 2001

During a compression molding process of Unidirectional Fiber Reinforced Plastic Composites, control of filling patterns in mold and distribution of fiber is needed to predict the effects of molding parameters on the flow characteristics. To obtain an excellent product and decide optimum molding conditions, it is important to know the relationship between molding conditions and viscosity. In this study, the anisotropic viscosity of the Unidirectional Fiber Reinforced Plastic Composites is measured by using the parallel plastometer. The model for flow state has been simulated by using the viscosity. The composites is treated as an incompressible New-tonian fluid. The effects of longitudinal/transverse viscosity ration A and slip parameter $\alpha$ on buldging phenomenon and mold filling patterns, are also discussed.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1888-1891
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• 1996

Recently, FLIC(Fluid In Cell) method has been widely used for the compressible. flow computation. A program which adopts the FLIC method and can analyze the flow conditions with arc in the interrupter was developed in our team. It was applied to the 800kV class gab circuit breaker for flow conditions with arc, and the results are presented and discussed in this paper.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.601-604
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• 2011

Plume flow-fields of aircraft nozzles are numerically investigated at various flight conditions for infrared signature analysis. A mission profile of subsonic unmanned combat aerial vehicle is considered for the requirement of each mission, associated engine and nozzles are selected through a performance analysis. Numerical results of nozzle plume flow-fields using a CFD code are analyzed in terms of thrust, maximum temperature. It is shown that maximum temperature increase for lower altitude and higher Mach number.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.141-147
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• 2011

A two-phase numerical model for plate-fin heat exchangers with plain fins and wave fins is studied incorporating the thermodynamic properties and the characteristics of fluid flow. The numerical simulations for the two fins in cryogenic conditions are earned out by employing a homogenous two-phase flow model with the CFD code ANSYS CFX. The heat transfer coefficients and the friction factor for nitrogen saturated vapor condensation process inside two types of plate fin heat exchanger are evaluated including the effects of saturation temperature (pressure), mass flow rate and inlet vapor quantity. The convective heat transfer coefficients and friction factors will be used for design of plate-fin type heat exchangers operating under cryogenic conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.3
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• pp.311-318
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• 2003

The present work evaluates the effects of mixing vane shape on the flow structure and heat transfer downstream of mixing vane in a subchannel of fuel assembly. by obtaining velocity and pressure fields. turbulent intensity. flow-mixing factors. heat transfer coefficient and friction factor using three-dimensional RANS analysis. Four different shapes of mixing vane. which were designed by the authors were tested to evaluate the performances in enhancing the heat transfer. Standard k-$\varepsilon$ model is used as a turbulence closure model. and. periodic and symmetry conditions are set as boundary conditions. The flow blockage ratio is kept constant. but the twist angle of mixing vane is changed. The results with three turbulence models were compared with experimental data.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.616-621
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• 2001

Flow-accelerated corrosion(FAC) is a phenomenon that results in metal loss from piping, vessels, and equipment made of carbon steel. FAC occurs only under certain conditions of flow, chemistry, geometry, and material. Unfortunately, those conditions are in much of the high-energy piping in nuclear and fossil-fueled power plants. Also, for domestic NPP secondary pipings whose operating time become longer, more evidences of FAC have been reported. The authors are studying on FAC management using CHECWORKS, computer code developed by EPRI. This paper is on the prediction results of metal loss by FAC in the one of CANDU type NPP secondary piping systems.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.282-289
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• 2000

Direct numerical solution for flow and heat transfer for Benard convection with a body is obtained using an accurate and efficient Fourier-Chebyshev collocation and multi-domain method. The flow and temperature fields are obtained fur different Rayleigh numbers and thermal boundary conditions of body. The body has adiabatic and constant temperature conditions. The existence of a body gives different flow and heat transfer fields in the system, compared to pure Benard convection. The flow and temperature fields are also affected by the thermal boundary condition of a body.

• Journal of Biosystems Engineering
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• v.23 no.2
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• pp.115-124
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• 1998

Over- and under-application of pesticides to crops have recently become main concerns regarding the environment conservation, product cost and firmer's safety. Thus, a uniform and optimal application method of pesticides was needed. The objective of study was to evaluate flow compensating characteristics of a variable flow control system for a boom sprayer using a laboratory setup. At the most variable conditions, the control system was acceptable with the flowrate control strategy. However, the sprayer control system became unstably fluctuating at the long execution time with small tolerance because of the constant valve on-time. This problem was solved by employing a variable on-time control. The optimal values for the damping ratio and the execution time were 2 and 1.0 sec, respectively, with the tolerances less than 3%. The performance of the control system at the optimal conditions were the response time of 3.8sec and the absolute steady-state error of 0.5% with the stable RCV and ROS ( < 1.0).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.58-64
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• 2004

The shrinkages of injection molded parts are different in molding operational conditions, resins and additives. The shrinkage of injection molded part for crystalline polymer, PBT (polybutylene terephthalate) has been studied for various operational conditions of injection molding and content of additives. Mica was used as a additive to PBT to examine the part shrinkage according to the mica content. The part shrinkages of mica contained PBT decreased as mica content increases. Higher injection temperature and injection pressure resulted in a lower shrinkage. As mold temperature increases the part shrinkage decreased. The part shrinkage of flow direction was less than that of the perpendicular direction to the flow for both pure and mica contained PBT. However the shrinkage difference between flow and perpendicular to flow directions decreased as mica content increased.