• International Journal of Highway Engineering
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• v.16 no.4
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• pp.87-95
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• 2014

PURPOSES: Evaluation of thermal conductivity and convection properties of asphalt mixture by using thermodynamics. METHODS: In this research, temperature prediction model based on thermodynamics is derived for asphalt mixture in transient state and it is verified with laboratory test results. RESULTS: The derived temperature prediction model shows good agreement with laboratory test results. CONCLUSIONS: It is concluded that the derived model based on thermodynamics and thermal properties in the literature are good enough to capture temperature variation in laboratory test. The approach based on thermodynamics can be applied to more complex temperature simulations.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.641-642
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• 2008

본 논문에서는 정열계 해석을 위해 짧은 해석 시간을 가지는 열전달 문제의 해석 기법에 대하여 제시한다. 특히, 열전달의 주요쟁점인 혼합 경계조건을 띄는 대류 문제의 열전달 계수 산정에 대하여 해석적 방법(analytic method)을 이용하여 구한 뒤, 수치해석적 방법(numerical method)인 유한요소법(F.E.M)으로 해석한다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.842-843
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• 2008

Many works on the temperature prediction of power apparatus have usually done by coupled magneto-thermal analysis. However, this method can not consider the internal gas or oil flow in the power apparatus. This paper proposes a new coupled magneto-thermal-flow analysis considering Navier-Stokes equations. The convection heat transfer coefficient is calculated analytically and is applied to the boundary condition to the proposed method. Temperature distribution of 145kV 40kA three-phase GIS bus bar model is obtained by coupled magneto-thermal-flow analysis and shows good agreement with the experimental data.

• Journal of computational fluids engineering
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• v.3 no.2
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• pp.65-72
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• 1998

From the Boltzmann equation with BGK approximation, a gas-kinetic BGK scheme is developed and methods for its efficient calculation, using the convergence acceleration techniques, are presented in a framework of an implicit time integration. The characteristics of the original gas-kinetic BGK scheme are improved in order for the accurate calculation of viscous and heat convection problems by considering Osher's linear subpath solutions and Prandtl number correction. Present scheme applied to various numerical tests reveals a high level of accuracy and robustness and shows advantages over flux vector splittings and Riemann solver approaches from Euler equations.

• Computers and Concrete
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• v.18 no.6
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• pp.1097-1112
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• 2016

Fire loading causes a critical collapse of RC (Reinforced Concrete) Structures since the embedded steels inside are relative week against high elevated temperature. Several numerical frameworks for fire resistance have been proposed, however they have limitations such as unstable convergence and long calculation period. In the work, 2-D nonlinear FE technique is proposed using Galerkin method for RC structures under fire loading. Closed-form element stiffness with a triangular element is adopted and verified with fire test on three RC slabs with different fire loading conditions. Several simulations are also performed considering fire loading conditions, water contents, and cover depth. The proposed numerical technique can handle time-dependent fire loading, convection, radiation, and material properties. The proposed technique can be improved through early-aged concrete behavior like moisture transport which varies with external temperature.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.302-307
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• 2003

Demand of the LCD-TV is remarkably increasing with development of the LCD technology in these days. Thus, this research has analyzed thermal problems such as heat transfer characteristics inside and outside the LCD-TV using numerical simulation and experiments. The simulated results have been compared with the experimental results using an infrared (IR) camera and T-type thermocouples. The optimal design of structure has been proposed to improve the thermal efficiency of radiation from the comparison.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.133-138
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• 2003

In this study, numerical investigation has been performed on the evolution of weld pool geometry with moving free surface during low-energy density laser welding process. The free surface elevates near the weld pool edge if ${\partial}{\sigma}/dT$ is dominantly negative. On the contrary, the free surface rise at the center of weld pool in case of mainly positive ${\partial}{\sigma}/dT$. The predicted weld pool width and depth with moving free surface are 5∼15%$5{\sim}15%$ greater than those with flat weld pool surface. It is considered that weld pool surface oscillation during melting process augments convective heat transfer rate in the weld pool.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.256-260
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• 2013

The fan-shroud plays the important role in cooling down the engine heat by the forced convection. As the fan-shroud is made by injection molding, the unbalance of the fan blades is inevitable, and its low frequency characteristics makes it easy to excite the resonances of the environmental structures. So controlling its vibration, specially the dominant vibration source of unbalance vibration, is one of key factor to improve the sound and vibration quality of the modern vehicles. This paper introduces the plane balancing method, the most appropriate way of controlling the fan-shroud by generating the acceleration orbit measured from 2 accelerometers, and proves its balancing effect by the experiment.

• Journal of Energy Engineering
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• v.10 no.3
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• pp.266-271
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• 2001

Buoyancy-driven natural convection is analysed by employing a linear stability theory in hori-zontal porous media with net through flow. Darcy's law is used to model the flow characteristics in porous media. Bated on the results of linear stability analysis, a heat transfer correlation was obtained by employing weakly nonlinear analysis. As the net through flow increases, the system becomes more stable and the effect of the Darcy-Rayleigh number on the Nusselt number decreases.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.20 no.4
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• pp.309-332
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• 2016

Finite element method has been applied to solve the fundamental governing equations of natural convective, electrically conducting, incompressible fluid flow past an infinite vertical plate surrounded by porous medium in presence of thermal radiation, viscous dissipation, Soret and Dufour effects. In this research work, the results of coupled partial differential equations are found numerically by applying finite element technique. The sway of significant parameters such as Soret number, Dufour number, Grashof number for heat and mass transfer, Magnetic field parameter, Thermal radiation parameter, Permeability parameter on velocity, temperature and concentration evaluations in the boundary layer region are examined in detail and the results are shown in graphically. Furthermore, the effect of these parameters on local skin friction coefficient, local Nusselt number and Sherwood numbers is also investigated. A very good agreement is noticed between the present results and previous published works in some limiting cases.