• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.4
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• pp.195-202
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• 2000

Recently, wave dissipating structures with porosity are widely used to improve habor tranquility and to reduce the wave overtopping rate. In this study, hydraulic model tests were performed to examine hydraulic efficiency of slit caissons, igloo blocks, and hollow blocks. The model tests showed that slit caissons were the most effective in dissipating wave energy under moderate wave conditions. Slit caissons and igloo blocks showed no significant difference in reducing wave overtopping rate. Hallow blocks are less effective in reducing wave overtopping rate than slit caissons and igloo blocks lU1der higher wave energy conditions.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.2
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• pp.175-183
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• 2016

A poroelastic composite material, containing different material phases and filled with fluids, serves as a model to formulate the overall ablative behaviors of such materials. This article deals with the assessment of variation in nondeterministic poroelastic properties of two-phase composite materials using micromechanical representative volume element (RVE) models. Considering the configuration and arrangement of pores in a matrix phase, various RVEs are modeled and analyzed according to their porosity. In order to quantitatively investigate the effects of microstructure, changes in effective elastic moduli and poroelastic parameters are measured via finite element (FE) analysis. The poroelastic parameters are calculated from the effective elastic moduli and the pore-pressure-induced strains. The reliability of the numerical results is verified through image-based FE models with the actual shape of pores in carbon-phenolic ablative materials. Additionally, the variation of strain energy density is measured, which can possibly be used to evaluate microstress concentrations.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.368-375
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• 1987

Effective thermal conductivity of the porous nuclear fuel has been investigated numerically. Difficulties associated with irregular shape of pore have been overcome by using the Body Fitted Coordinate Systems. A computer code has been developed to solve the governing equation with appropriate boundary conditions by transforming from the Cartesian coordinates to the nonorthogonal curvilinear coordinates. The effects of the porosity have been investigated. For a convenient use of the result, a correlation equation was suggested under the assumption of circular pore. The computation results by the assumption of randomly oriented elliptic pore has been agreed more closely to existing experimental result than that by the assumption of circular pore.

• The Journal of Engineering Geology
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• v.17 no.2 s.52
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• pp.205-215
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• 2007

In this study, the soil characteristics are analyzed using the result of various soil tests as an object of the soil layer of natural slopes in landslides areas. Also, the relationship with landslides and interrelation with each soil properties are analyzed. The landslides in three areas with different geological condition are occurred due to heavy rainfall in same time. The geology of Jangheung area, Sangju area and Pohang area is gneiss, granite, and the tertiary sedimentary rock, respectively. However soil characteristics have a little differentiation to geological condition, the soils sampled from landslide area have higher proportion of fine particle and porosity, and lower density than those from non landslide area. In case of same geological condition, landslides are occurred in the terrain slope with high permeability. The permeability is mainly influenced by the soil characteristics such as particle size distribution, porosity, particle structure, and the geological origins such as weathering, sedimentary environment. The soil layer with high internal friction angle is more stable than that with low internal friction angle in all geological condition. The permeability is mainly influenced by effective particle size, coefficient of uniformity, coefficient of gradation, porosity, density and so on. Also, those have interrelation with each factor. These interrelations are similar in all study area. Meanwhile, in proportion as the void ratio and the porosity rises the permeability increases.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.80-87
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• 2010

This study was conducted to develop a reservoir modelling workflow to reproduce the heterogeneous distribution of effective permeability that impacts on the performance of SAGD (Steam Assisted Gravity Drainage), the in-situ bitumen recovery technique in the Athabasca Oil Sands. Lithologic facies distribution is the main cause of the heterogeneity in bitumen reservoirs in the study area. The target formation consists of sand with mudstone facies in a fluvial-to-estuary channel system, where the mudstone interrupts fluid flow and reduces effective permeability. In this study, the lithologic facies is classified into three classes having different characteristics of effective permeability, depending on the shapes of mudstones. The reservoir modelling workflow of this study consists of two main modules; facies modelling and permeability modelling. The facies modelling provides an identification of the three lithologic facies, using a stochastic approach, which mainly control the effective permeability. The permeability modelling populates mudstone volume fraction first, then transforms it into effective permeability. A series of flow simulations applied to mini-models of the lithologic facies obtains the transformation functions of the mudstone volume fraction into the effective permeability. Seismic data contribute to the facies modelling via providing prior probability of facies, which is incorporated in the facies models by geostatistical techniques. In particular, this study employs a probabilistic neural network utilising multiple seismic attributes in facies prediction that improves the prior probability of facies. The result of using the improved prior probability in facies modelling is compared to the conventional method using a single seismic attribute to demonstrate the improvement in the facies discrimination. Using P-wave velocity in combination with density in the multiple seismic attributes is the essence of the improved facies discrimination. This paper also discusses sand matrix porosity that makes P-wave velocity differ between the different facies in the study area, where the sand matrix porosity is uniquely evaluated using log-derived porosity, P-wave velocity and photographically-predicted mudstone volume.

• Tunnel and Underground Space
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• v.21 no.1
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• pp.33-40
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• 2011

This study focuses on having a temperature and water pressure effects on the change of material properties of rocks. Granite and limestone specimens from Gagok Mine were thermally treated with predetermined temperatures of 200, 300, 400, 500, 600 and $700^{\circ}C$ (excepting $700^{\circ}C$ for limestone) to estimate the reduction of material properties of rocks caused by heat. Specific gravity, effective porosity, elastic wave velocity, uniaxial compressive strength, Young's modulus and Poisson's ratio for pre-heated specimens were measured. With increasing temperature, material properties of both rock specimens change sequentially. Significant changes of specific gravity, effective porosity and elastic wave porosity occur above $400^{\circ}C$ for granite and $300^{\circ}C$ for limestone. Changes of uniaxial compressive strength, Young's modulus and Poisson's ratio seem to be similar to those of physical properties. GSI of 500, 600 and $700^{\circ}C$ specimens inferred by using uniaxial compressive strength and Young's modulus of preheated granite specimens is found to be 81, 66 and 58 each. In case of pre-heated limestone specimens of 400, 500 and $600^{\circ}C$, the corresponding GSI is 76, 71 and 65 each. 500, 600 and $700^{\circ}C$ granite specimens and 400, 500 and $600^{\circ}C$ limestone specimens were pressurized to 7.5 MPa and their effective porosity, elastic wave velocity, uniaxial compressive strength and Young's modulus were measured. The average value of material properties (mentioned above) of 500, 600 and $700^{\circ}C$ granite specimens under water pressure compared with material properties of non-pressurized pre-heated specimens exhibits the reduction of 7.6, 11.3 and 14.9%, respectively. In case of 400, 500 and $600^{\circ}C$ limestone specimens under water pressure, the average value of material properties decreases by 8.2, 13.8 and 21.9%, respectively.

• Journal of the Korean GEO-environmental Society
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• v.19 no.5
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• pp.5-12
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• 2018

The porosity formation by the addition of additives was found to be the highest in the case of aluminum powder 3% and $Ca(OH)_2$ 2% under the condition that strength was maintained. The optimum mixing ratio of the binder was shown to be the most effective at (Ash+Food waste+clay):(water glass+colloidal silica) 7:3, and the temperature response is most economical and effective at $1,000^{\circ}C$. The optimal mixing ratio is the strength in 30% of ash, 30% of clay and 10% of food waste, which is the effective in non-point pollution water treatment. Filter media produced under optimal mixing conditions were analyzed as $SiO_2$ 65.8%, density $1.4g/cm^3$, porosity 25.6%, pH 9.8, and no hazardous substances were detected. As a result of the filtration of the water treatment, the mean concentration of the filtered SS was $14.06mg/{\ell}$, and the removal efficiency of SS was 90%, the recovery rate of the reversal is 97.1%. This enables the development of filter media considering economic efficiency and efficiency as well as the utilization of waste resources, enabling high value added of waste resources.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.1
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• pp.9-20
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• 1991

The characteristics of the unconsolidated sediment in Gwangyang bay was analyzed from the core samples. The porosity of the sediment showed irregular variation with respect to the sedimentation depth, which indicated that sediment weight-induced consolidation was not significant. Numerical analysis for the mechanical and hydraulic behavior of the unconsolidated sediment due to the tidal sea level change was processed. Because of the delayed excessive pore pressure change in the very low permeable mud medium, the magnitude of the excessive pore pressure for the duration of the minimum sea level exceeded the total stress from the sea water weight, which resulted in the negative (tensional) effective stress below the top surface. The in-situ effective stress, obtained by superposing the tensional effective stress on the solid weight-induced compressive stress, was remained to be tensile (quick-sand condition) near the top surface of the mud deposit. The occurrence of the quirk-sand condition provided a theoretical evidence for the insignificant consolidation and the irregular porosity variation of the sediment. When the sand is distributed on the top surface of the mud layer, the quick-sand condition occurred below the sandy mud layer and the downward movement of sand particles was facilitated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.739-746
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• 2004

The plastic deformation behavior of an aluminum alloy containing a particle and porosities was investigated at room temperature during equal channel angular pressing (ECAP). Finite element analysis by using ABAQUS shows that ECAP is a useful tool for eliminating residual porosity in the specimen, and more effective under friction condition. The simulation, however, shows considerably low density distributions for matrix near a particle at which many defects may occur during severe deformation. Finite element results of effective strains and deformed shapes for matrix with a particle were compared with theoretical calculations under simple shear stress. Also, based on the distribution of the maximum principal stress in the specimen, Weibull fracture probability was obtained for particle sizes and particle-coating layer materials. The probability was useful to predict the trend of more susceptible failure of a brittle coating layer than a particle without an interphase in metal matrix composites.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.04a
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• pp.7-16
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• 1999

The aim of this research was to evaluate the influences of coating components and structures on ink absorbency. The ink absorbency was measured as porosity, K&N ink absorption, gloss and ink set-off. In order to obtain the relationship between the coating structure and the ink absorbency, the binder level was adjusted and two types of pigments were examined. One of the pigments was known to make the porous coating structure and the other one had strong ink affinity. The effects of coating components were studied by applying six different types of latex and various additives . In this research, CLC(cylindrical laboratory coater) and Prufbau printability tester were used. It was found that the decreasing latex dosage and introducing porous pigment were effective solutions to increase ink absorbency. However, the ink absorbency could not be improved by applying the fine pigment even though it had strong ink affinity. Among the characters of the latex, particle size and surface tension were found to have the strong effect on ink absorbency. The ink absorbency increased with large particle size and low surface tension latex. The additives were varied and it was found that applying to the top coating was effective.