• The KSFM Journal of Fluid Machinery
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• v.11 no.2
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• pp.20-28
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• 2008

Recently, butterfly valves are used as control valves for industrial process. However, there are not so many reports on cryogenic butterfly valves in spite of broad application in LNG storage station and LNG carriers. Present study is focused on the investigation of the detailed hydrodynamic and aerodynamic characteristics of cryogenic butterfly valves to contribute to the operation during the handling on LNG transportation system, and to the practical utilization in design of butterfly valves and actuators. The results show that large recirculation vortices in the region downstream of the valve are founded and the cavitation flows are intensively generated on the surface of valve disc at the relatively small opening angle. The aerodynamic characteristics, lift, drag and torque, acting on the valve disc are calculated. The pressure distribution and the pressure loss coefficient of the cryogenic butterfly valve show almost similar pattern with those of the butterfly valve which is used on the normal temperature.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.1
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• pp.7-15
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• 2008

Pressure Sensitive Paint(PSP) means a reacting paint in pressure. The calibration of PSP and the wind tunnel test of PSP painted model are required to measure pressure by using PSP. Therefore, the post processing from these results shows the information and image of the pressure distribution. PSP can show the information of total pressure from the wind tunnel test and the calibration. In this study, equipments of PSP are composed, and experiment is accomplished by using PSP. The surface pressure distribution around the wall of nozzle is measured by PSP. The measured pressure has similar results to those of the CFD and pressure tap measurement.

• Textile Coloration and Finishing
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• v.25 no.2
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• pp.134-139
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• 2013

A tenter is very important to dry and heat-set fabrics in textile dyeing and finishing industry. However, the tenter machine typically utilizes more than 80% of all the power in dyeing system, and yet is one of the primary machine which affects quality of fabrics. Therefore, performance optimization of the tenter machine is required to reduce energy consumption and enhance quality of fabrics. To optimize the tenter machine, it is important to maintain the uniform flow rate, which can be obtained by optimizing a nozzle geometry. In this study, emboss hole angle was investigated as main parameter in flow rate uniformity and heat flux efficiency. The analysis results were compared with those acquired from bench-scale dryer test in the laboratory. The tenter machine performance simulated by Computational Fluid Dynamics(CFD) was optimized by controlling emboss hole angle.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.95-101
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• 2012

An electric water pump for engine cooling system has an advantage which particularly in the cold start, the use of the electric water pump saves fuel and leads to a corresponding reduction in emissions. The canned type electric water pump without mechanical sealing elements was selected to meet the requirements for operational reliability and life. However, the electric water pump for internal combustion engine generates much more heat loss than for hybrid electric vehicle since it is operated by the electric power of high current and low voltage. In this study, the fluid flow and thermal characteristics of the canned type electric water pump as an inverter integrated water pump has been investigated under the effects of heat generation. The analysis conditions such as outdoor air temperature of $125^{\circ}C$, water pump speed of 6000 rpm, coolant temperature of $106^{\circ}C$ and coolant flow rate of 120 L/min was used as a standard condition. Therefore, flow fields and temperature distribution inside the water pump were obtained. Also, we checked the feasibility of the canned type for the electric water pump in comparison with the mechanical seal type.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.2
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• pp.145-150
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• 2017

Air brake valves are widely used in automotive braking systems and the Korean automobile industry depends on importing them. Therefore, we should develop the technical expertise for their domestic production. In this study, air brake valves were analyzed that can be used in a variety of automobiles. Computational fluid dynamics analysis, static structural analysis, and hyper-elastic analysis were carried out. Before production of an air brake valve system, the performance of different parts has to be evaluated, for instance by using finite element analysis. The structural stability of the product can be determined using static dynamics. The compression behavior of the O-ring is predictable by nonlinear hyper elastic analysis, although errors are possible due to one-way loading. This simulation study can both save time and reduce costs compared to the development of experimental prototypes.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.3
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• pp.9-18
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• 1997

Experimental and numerical studies are carried out to investigate flow characteristics around an axisymmetric body with and without a compound propulsor. The effects of a compound propulsor are investigated as measuring the surface pressure distribution and the velocity profiles using LDV system in the cavitation tunnel of KRISO. The incompressible Reynolds-Averaged Navier-Stokes(RANS) equations are also solved using the finite volume method. The standard k-${\varepsilon}$ turbulence model is adopted for turbulence closure. In order to calculate propeller-hull interaction, the induced velocity calculated by lifting surface theory is considered as the boundary condition at the propeller plane. The experimental data obtained in this study can provide a useful database for development and validation of CFD code.

• International Journal of Automotive Technology
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• v.3 no.2
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• pp.47-52
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• 2002

The integration of CAD/CAM/CAE in product development is the key to realize concurrent engineering. Generally, different systems are employed in product development departments. These different systems create a lot of trout)toes such as difficulty in communication, misunderstanding and so on. A new approach to integrate CAD/CAM/CAE in one system based on CATIA thor the end-to-end process in cylinder head development is presented. Hulti Model Technology (MMT) is used to create consistent and associated CAD models for the end-to-end process in cylinder head development. The concept and method to create and organize multi models are discussed. A typical four-layer structure of HHT for mechanical products is defined. The multi level structure of the cylinder head models based on MMT is provided. The CAD models of cylinder head created based on MMT can be used as the consistent model. All models in the downstream of cylinder head development such as structure analysis, CFD, sand core design , casting simulation and so oil are associated with the CAD models. Practice shows the approach in this paper enables the development process to be carried concurrently and can obviously shorten time to the market, reduce product cost and improve product quality.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.8
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• pp.26-33
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• 2005

Smart UAV, which adopting tiltrotor aircraft concept, requires vertical take-off and landing, long endurance and high speed capability. These contradictable flight performances are hard to meet unless the operation of flap system which should reveal optimal performance for each flight mode. In order to design SUAV flaperon satisfying the three performance requirements, various configurations are generated and their aerodynamic performances are analyzed using numerical flow computations around flap systems. Considering aerodynamic performance and structural simplicity, a final flap configuration is selected and the performance is validated through the wind tunnel testing for 40% scale model.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.6
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• pp.468-476
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• 2016

In this study, the conic winglet which is made by rotating wing tip airfoil by each 3 axis is applied to the dual type combined fan to reduce the wing tip leakage loss. Computational Fluid Dynamics is used to calculate the loss and optimum technique is used to get minimum loss. Optimization results shows that total pressure loss coefficient was reduced by 3.4 %, and optimization model was a bended shape at the end of wing forward to pressure side.

• Journal of the Korean Society of Safety
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• v.21 no.1 s.73
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• pp.35-40
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• 2006

A study on fire phenomena in a subway transit mass station has been carried out as a part of disaster prevention plan at the subway station. The ventilation facilities installed in both the platform and the trackway are designed to convert into a smoke exhaust system in emergency situation, creating such an environment as necessary for evacuation. 3 dimensional Numerical Simulations based on the CFD are carried out using a simulation tool, Fire Dynamic Simulator. Additionally, four different vent modes are made and performances are compared with the original design mode and each other to find better operation of vents at both the platform and the trackway in case of fire. From the result, an vent operational characteristics under the condition of installed PSD is clarified for the effective smoke and heat removal from the platform area compared with non installed PSD.