• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.172-179
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• 2001

A numelical model has been developed for the permeable coastal structures to simulate hydraulic characteristics on the permeable slopes, which interact with internal flow field of the structures. The model includes hydraulics in the porous medium. Numerical model was calibrated using hydraulic model experiments performed in 2-D wave flume in the Institute of Orean Hydraulics in PKNU. Good agreement were obtained with the model which employed inertia resistance term than with the conventional model, PBREAK.

• KSBB Journal
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• v.10 no.5
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• pp.482-490
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• 1995

The relationship between pressure drop and liquid flow rate, for an axial and a radial flow chromatographic column packed with compressible porous media was theoretically analyzed using modified Kozeny-Carman equation. The results were compared with experimental observations obtained using compressible DEAE-agarose as a model medium. At 2-9 psi range studied, the theoretical derivation accounting for 'gel compression' effect predicted simple Langmuirian type response of volumetric flow rate to changes in pressure drop. On the other hand, the experimental response was more or less sigmoidal. At the same pressure drop, radial column showed 2-3 times higher flow rates than those of axial column both theoretically and experimentally. Using r-HBsAg crude extract, protein resolution effects between the two types of columns at different flow rates were compared side-by-side. It turned out that, though general chromatographic behavior was very similar, axial column was somewhat superior in terms of r-HBsAg recovery yield and specificity. However, the number of theoretical plates analysis indicated the protein resolution effects were comparable.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.109-122
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• 1993

ln this paper, a finite element analysis procedure is proposed for the incremental multi-step excavations in a fluid-saturated porous medium such as saturated soil ground. As the basis of derivation, Biot's equation was used. The proposed procedure was applied to some one- and two-dimensional problems under incremental excavations. Unsaturated cases as well as saturated cases were considered for comparison. Through numerical tests, the effects of permeability and excavation speed on the deformation history was investigated. Results showed that pore pressure built up during incremental excavation has a significant effect on the deformation and stresses of solid skeleton and validated the use of the present procedure for the analysis of multi-step excavations in fluid-saturated media such as in saturated shallow ground.

• Journal of Ocean Engineering and Technology
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• v.24 no.1
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• pp.116-122
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• 2010

The aim of this study is to examine the effects of shape and plane arrangement of submerged breakwaters on 3-D wave breaking characteristics over them. First, the numerical model, which is able to consider the flow through a porous medium with inertial, laminar, and turbulent resistance terms, i.e. simulate directly WAve Structure Seabed/Sandy beach interaction, and can determine the eddy viscosity with a LES turbulent model in a 3-Dimensional wave field (LES-WASS-3D), has been validated by a comparison with Goda's equation for breaking wave heights. And then, using the numerical results, the wave breaking points over the crest of submerged breakwaters have been examined in relation to the shape and plane arrangement of submerged breakwaters. Moreover, the wave height distribution and upper flow around submerged breakwaters have been also discussed, as well as the distribution of the wave breaking points over the beach.

• Journal of Radiation Protection and Research
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• v.17 no.2
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• pp.49-59
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• 1992

A new model was developed in order to investigate the effects of chelating agents on the migration of a radionuclide in the form of ion or chelate. The migration behavior of the chelated radionuclide was analyzed by formulating a convective-dispersion transport equation which included a degradation of chelating agent and chelated radionuclide. The mathematical model was analytically solved and checked with the existing retardation factor. The results show that the migration velocity of the chelated radionuclide was much faster than the ionic one due to the decreased retardation. Therefore, it was concluded that a new remedial action should be developed to reduce the generation and release of chelating agents from the nuclear power plant into the environment.

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.27-33
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• 2016

The aim of numerical study is the investigation of the solid and fluid temperatures in a reformer tube and chemical reaction characteristics of different steam-carbon ratio. We considered conjugate heat transfer contain radiation, convection and conductive heat transfers. This is because steam reforming reaction of hydrocarbon occurred high temperature conditions up to 800 K- 1000 K by using commercial computational fluid dynamics (CFD) code (Fluent ver. 13.0). For numerical simulation, the Reynolds-Averaged Navier-Stokes, momentum and energy equation were employed. In addition, inside of reformer tube is assumed as the porous medium to consider the Nichrome-based catalyst. To analysis characteristics of tube temperature in chemical reaction, we changed steam-methane ratio(SCR) from 1 to 6. As increased SCR, the higher tube temperature and methane conversion were observed. It was obtained that the highest hydrogen production held in SCR of 5.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.109-118
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• 1999

Recently, transport parameters of conservative solutes such as KCl in a porous medium have been successfully determined using time domain reflectometry (TDR) . This study was initiated to Investigate the applicability of TDR technique to monitoring the fate of a heavy metal ion in a sandy soil and the distribution of its concentration along travel distance with time. A column test was conducted in a laboratory that consists of monitoring both resident and flux concentrations of $ZnCl_2$in a sandy soil under a breakthrough condition. A tracer of $ZnCl_2$(10 g/L) was injected onto the top surface of the sample as pulse type as soon as a steady-state condition was achieved. Time-series measurements of resistance and electrical conductivity were performed at 10 cm and 20 cm of distances from the inlet boundary by horizontal-positioning of parallel TDR metallic rods and using an EC-meter for the effluent exiting the bottom boundary respectively. In addition. Zn ions of the effluent were analyzed by ICP-AES. Since the mode and position of concentration detected by TDR and effluent were different, comparison between ICP analysis and TDR-detected concentration was made by predicting flux concentration using CDE model accommodating a decay constant with the transport parameters obtained from the resident concentrations. The experimental results showed that the resident concentration resulted in earlier and higher peak than the flux concentration obtained by EC-meter, implying the homogeneity of the packed sandy soil. A close agreement was found between the predicted from the transport parameters obtained by TDR and the measured $ZnCl_2$concentration. This indicates that TDR technique can also be applied to monitoring heavy metal concentrations in the soil once that a decay constant is obtained for a given soil.