• Geomechanics and Engineering
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• v.21 no.1
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• pp.85-93
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• 2020

In this article, the generalized thermoelastic theory with fractional derivative is presented to estimate the variation of temperature, the components of stress, the components of displacement and the changes in volume fraction field in two-dimensional porous media. Easily, the exact solutions in the Laplace domain are obtained. By using Laplace and Fourier transformations with the eigenvalues method, the physical quantities are obtained analytically. The numerical results for all the physical quantities considered are implemented and presented graphically. The results display that the present model with the fractional derivative is reduced to the Lord and Shulman (LS) and the classical dynamical coupled (CT) theories when the fractional parameter is equivalent to one and the delay time is equal to zero and respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.8
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• pp.667-673
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• 2003

Recent trends in the electronic equipment indicate that the power consumption and heat generation in a chip increase as the components are miniaturized and the computing speed becomes faster. Suitable heat dissipation is required to ensure the guaranteed performance and reliable operation of the electronic devices. The aim of the present study is to investigate the forced-convective thermal-hydraulic characteristics of a pin-fin heat exchanger as a candidate for cooling system of the electronic devices. The influence of the structure of the pin-fin assembly on heat transfer is investigated by porous medium model. The results are compared with the experimental data or correlations of several researchers for the heat transfer coefficients for the channel flow with pin-fin arrays. Finally, the effects of design parameters such as the pin-fin diameter and the spacing are examined.

• Journal of Environmental Science International
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• v.5 no.4
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• pp.495-511
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• 1996

The quantitative study of the groundwater contamination in a porous media is a difficult task. For complex problems, numerical solutions are the most effective means to study the movement of contaminants in the groundwater, The solute transport model used in this study has proved to be an efficient tool to model contaminant transport for complex problems. The model demonstrates its effectiveness in reproducing the coniamination by ihlorides of the groundwater at the landfill site due to leachath from the wastes. It describes the two dimentional solute transport and alteration of the water quality and forecasts the contamination for different management alternatives of the landfill. The model also indicates how the groundwater contamination can be contained within the lower site if a barrier is constructed downstream of the disposed wastes.

• Tunnel and Underground Space
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• v.8 no.4
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• pp.275-286
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• 1998

The effective permeability and the representative element volume(REV) of fracture network model were evaluated based on the parameters such as permeability tensor, principal permeability and the direction of principal permeability. The effective permeability ranges between the harmonic mean and the arithmetic mean of the local permeabilities of subdivided blocks. From the numerical experiments, which were for investigating the influence of model volume on the variation of flux for the cubic models, it was found that the variation of flux became reduced as the model volume approached REV. The variation of groundwater flux into the tunnel in the fracture network model was mainly dependent on the ratio of the tunnel length to model size rather than REV. And it was found that groundwater flux into the tunnel was not completely consistent between the fracture network model and the equivalent porous media model, especially when the ratio of the tunnel length to model size is small.

• Journal of computational fluids engineering
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• v.14 no.2
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• pp.39-45
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• 2009

In engine room, proper enclosure system is preferable for reducing noise level but the enclosure system in the engine room causes bad influence on cooling performance due to poor ventilation. Cooling efficiency of the enclosure system can be improved by varying fan speed and proper flow path for ventilation. In this study, numerical analysis is performed to assess cooling effect of the enclosure system using finite volume method. The RNG k-$\varepsilon$ model is adopted for turbulence model along with heat exchanger model and porous media model for heat exchanger analysis, and moving reference frame model for rotational fan. Verification result shows reasonable agreement with experimental data. Analysis results show direct effect of velocity and temperature distribution on cooling ability in the enclosure system. Enclosure system of case B shows high heat transfer coefficient and has the smallest area ratio of opened flow passages which is good for noise level reduction.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.243-247
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• 2004

Tile development of a porous iron-oxide coated sand filter system can be modelled with the analytical solution of tile transport equation in order to obtain the operating parameters and investigate the mechanism of arsenic removal. The adsorbed amount from the model simulation showed the limitation of adsorption removal during arsenic transport. A loss reaction term in the transport equation plays a role in the mass loss in column conditions, and then resulted into the better model fitting, particularly, for arsenate. Further, the competitive oxyanions delayed the breakthrough near MCL (10 $\mu$g/L) due to the competitive adsorption. This is the reason why arsenate can be strongly attracted in tile interface of an iron-oxide coated sand, and competing oxyanions can occupy the adsorption sites. Therefore, arsenic retention was regulated by non-equilibrium of arsenic adsorption in a porous iron-oxide coated sand media. The transport-limited process seemed to be affect the arsenic adsorption by coated sand.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.7
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• pp.64-70
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• 2022

The aim of this study is to improve the purification efficiency of odor gas by increasing the contact area between an odor gas and adsorbent. To analyze the flow in the adsorption tower, the flow characteristics in the hollow activated carbon-adsorption tower are identified by applying the loss model, which is a porous flow analysis model. The flow characteristics are investigated for pressure loss, velocity distribution, turbulent kinetic energy, and residence time distribution. The results show that the hollow adsorption tower performs better than the solid adsorption tower in terms of pressure loss and performance. The inner diameter of the hollow region inside the adsorption tower is 0.64 m (Di/Do = 0.37). Furthermore, the adsorbent performance is unaffected even when adsorbent stages are installed to replace the adsorbent.

• Journal of the Mineralogical Society of Korea
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• v.22 no.4
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• pp.313-324
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• 2009

We explore the effect of particle shape and size on 3-dimensional (3D) network and pore structure of porous earth materials composed of glass beads and silica gel using NMR micro-imaging in order to gain better insights into relationship between structure and the corresponding hydrologic and seismological properties. The 3D micro-imaging data for the model porous networks show that the specific surface area, porosity, and permeability range from 2.5 to $9.6\;mm^2/mm^3$, from 0.21 to 0.38, and from 11.6 to 892.3 D (Darcy), respectively, which are typical values for unconsolidated sands. The relationships among specific surface area, porosity, and permeability of the porous media are relatively well explained with the Kozeny equation. Cube counting fractal dimension analysis shows that fractal dimension increases from ~2.5－2.6 to 3.0 with increasing specific surface area from 2.5 to $9.6\;mm^2/mm^3$, with the data also suggesting the effect of porosity. Specific surface area, porosity, permeability, and cube counting fractal dimension for the natural mongolian sandstone are $0.33\;mm^2/mm^3$, 0.017, 30.9 mD, and 1.59, respectively. The current results highlight that NMR micro-imaging, together with detailed statistical analyses can be useful to characterize 3D pore structures of various porous earth materials and be potentially effective in accounting for transport properties and seismic wave velocity and attenuation of diverse porous media in earth crust and interiors.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.181-185
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• 2001

Three-dimensional finite-element-based numerical model of turbulent flow, heat transfer, macroscopic solidification and inclusion trajectory in a continuos steel slab caster was developed Turbulence was incorporated using the Improved Low-Re turbulence model with positive preserving approach. The mushy region was modeled as the porous media with average effective viscosity. A series of simulations was carried out to investigate the effects of the casting speed, the slab size, the delivered superheat the immersion depth of the SEN on the transport phenomena. In the absence of any known experimental data related to velocity profiles, the numerical predictions of the solidified profile on a caster was compared with breakouts data and a good agreement was found.

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.35-40
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• 2006

In recent years, there's been strong demand for seawalls that havea gentle slope and permeability that serveswater affinity and disaster prevention from wave attack. The aim of this study is to examine wave transformation, including wave run-up that propagates on the coastal structures. A numerical model based on the weak nonlinear dispersive Boussinesq equation, together with the unsteady nonlinear Darcy law for fluid motion in permeable layer, is developed. The applicability of this numerical model is examined through Deguchi and Moriwaki's hydraulic model test on the permeable slopes. From this study, it is found that the proposed numerical model can predict wave transformation and run-up on the gentle slope with a permeable layer, but can't show accurate results for slopes steeper than about 1:10.