• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.13-14
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• 2022

This study investigated the effect of fly ash content on the isothermal hydration heat of cement pastes. Two different pastes with fly ash content were studied to cure at 35℃. The hydration heat flow deceleration stage of slurry was simulated and compared by Jander Equation and Ginstling-Brounshtein Equation. The results show that Jander Equation and Ginstling-Brounshtein Equation have certain defects in the modeling of the deceleration stage of the heat flow of cement fly ash paste, and the fitted curve can not describe the deceleration stage well.

• Structural Engineering and Mechanics
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• v.82 no.5
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• pp.679-690
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• 2022

This research effort examines the flow behavior and heat transfer assessment of water carrying iron (iii) oxide magnetic fluid due to a rotating and moving plane lamina under the influence of magnetic dipole. The effect of rotational viscosity and magnetic body force is taken into consideration in the present study. The involvement of the moving disk makes a significant contribution to the velocity distribution and heat transfer in rotational flow. Vertical movement of the disk keeps the flow unsteady and the similarity transformation converts the governing equation of unsteady flow into nonlinear coupled differential equations. The non-dimensional equation in the present system is solved through the finite element procedure. Optimizing the use of physical parameters described in this flow, such results can be useful in the rotating machinery industries for heat transfer enhancement.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.3
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• pp.218-226
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• 1994

Laminar flow and heat transfer in a channel with blockages are obtained numerically in a Reynolds-number range of $100{\leq}Re{\leq}400$. A boundary-fitted curvilinear coordinate system is generated for irregular boundary of the physical region, and solutions of Navier-Stokes equation and energy equation are obtained by finite analytic method in the transformed computational domain. The flow separates in downstream of the blockage and the length of separated-flow region increases with Reynolds number. The heat flux is high on the top of the blockages and increase in the heat transfer occurs where the fluid reattaches the wall. Comparison between computed streamlines and experimental flow-visualization is also presented and discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.1-11
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• 1999

The three-dimensional laminar mixed convection flow between the conductive printed circuit boards. on which the heat generating rectangular blocks are uniformly distributed, has been examined in the present study. The flow and heat-transfer characteristics are assumed to be pseudo periodic in the streamwise direction and symmetric in the cross-stream direction. Using an algorithm of SIMPLER, the continuity equation. the Navier-Stokes equations and the energy equation are solved numerically in the three-dimensional domain Inside the channel. The convective derivative terms are discretized by the QUICK scheme to accurately capture the flow field. The flow and the heat transfer characteristics are thoroughly examined for various Re and Gr.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.14 no.4
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• pp.293-299
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• 1985

This paper describes an economical prediction procedure for heat transfer phenomenon through a channel containing an abrupt asymmetric expansion in flow cross-seetional area. Numerical solutions for the flow field are obtained by the finite difference numerical method applied to the modified boundary layer equations. Modified boundary energy equation is used to analyze heat transfer as modified boundary momentum equation. Predictions of the method compare very favorable with exprimental data. Results of this study by modified boundary layer equation are as follows : 1. The computation time required for the scheme is at least an order of magnitude less than for the numerical solution of the full Navier-stokes and Energy eguations. 2. In laminar flow, the maximum heat transfer occurs downstream of the reattachment point.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.1
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• pp.1-10
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• 1994

The flow and heat transfer characteristics behind a backward facing step located in a vertical channel has been studied. In this study, the numerical prediction has been performed by solving the Navier-Stokes equation and energy equation simultaneously with the SIMPLE algorithm embedied in TEACH code. Local heat flux was measured by using Schlieren Interferometer. The flow visualization was performed using the cylindrical lens and the laser beam that is scattered by the supplied glycerine particles. The velocity and temperature distributions, recirculation region, reattachment length, and local heat flux are obtained under the various parameters to investigate the buoyancy effect on the flow and heat transfer characteristics behind the step.

• Journal of the Korean Mathematical Society
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• v.57 no.2
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• pp.313-329
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• 2020

In this paper, we derive various differential Harnack estimates for positive solutions to the nonlinear backward heat type equations on closed manifolds coupled with the Ricci-Bourguignon flow, which was done for the Ricci flow by J.-Y. Wu [30]. The proof follows exactly the one given by X.-D. Cao [4] for the linear backward heat type equations coupled with the Ricci flow.

• Journal of the Korean Mathematical Society
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• v.44 no.3
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• pp.585-603
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• 2007

The author studies the local $H\ddot{o}lder$ convergence of the solution to an evolution equation of p-Ginzburg-Landau type, to the heat flow of the p-harmonic map, when the parameter tends to zero. The convergence is derived by establishing a uniform gradient estimation for the solution of the regularized equation.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.13 no.1
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• pp.5-13
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• 1984

This analysis of numerical procedure is prediction of laminar flow and heat transfer at two dimension and steady flow in asymmetric sudden expansion channel. At former study, to analyse the flows with separation, the full Navier-Stokes equation is used, but there are many difficulties to analyse, and although significant progress has been made in the development of efficient computational methods for the Navier-Stokes equations, very large computation times are still required. In case of reward-facing flow, boundary-layer equation is used instead of full Navier-Stokes equation to analyse velocity fields, and result of this numerical analysis is good agreement with the given experimental study. In this case, since the computer time required for the boundary-layer calculation is an order of magnitude less than required for the solution of the full Navier-Stokes equation, this boundary-layer model provides a good approximate solution.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.6
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• pp.1551-1558
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• 1994

An experiment was conducted to investigate whether an equation of heat transfer coefficient derived form energy equation of two-phase plug flow can be actually applied to the industrial field. The heat is constantly transfered to the sand beds from the wall of heat exchanger while the sand moves down through cylindrical heat exchanger by gravity from feed hooper. To increase heat transfer, turbulators such as glass ball and steel pipe packings were used. In addition, the experiment in the case of fluidizing the sand beds was also carried out. The temperatures of the sand beds and the wall were measured along the heat exchanger axis. The density and porosity of the sand beds were also measured. The deviations of the mean velocity of sands from the velocity on the wall surface because of the slip conditions on the wall were negligible (within 3%). The heat transfer coefficients when the turbulators were used and when the sand beds were fluidized were found to be much greater than those of the plain plug flow.