• Journal of the Korean Ceramic Society
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• v.33 no.12
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• pp.1394-1402
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• 1996

The Silica gel with the density of 0.2g/cm3 and porosity of 90% was synthesized. The silica wet gel was dried and heat-treated under the ambient pressure after modification of the wet gel surface by TMCS. Specific surface area total pore volume and mean pore radius of dried gel were all increased with increasing heat treatment temperature and confirmed about 1400m2/g, 4.5cc/g and 8 nm respectively after heat treatment above 25$0^{\circ}C$. But the pore size distribution of dried gel was in the range of 1-100nm and was almost indepen-dent of temperature. As the result of external shape pore characteristics and microstructure of gel using SEM similar properties were observed between the silica gel synthesized in this study and the silica aerogel through the super critical drying.

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.113-119
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• 1995

The green body was fabricated by a new forming method, pressureless powder packaing forming method, and the characteristics of sintered specimen were investigated. It was found that alumina ceramics prepared by the present method showed porous structure with narrow pore size distribution, and in case of abrasive powder sintered body, compared with dry-pressed specimen, had the nearly same density. Especially, the specimen prepared with spray-dried granules showed the characteristic that granules were not either deformed or fractured during forming and sintering process. Therefore, it was found that this new forming method was effective method in fabrication of porous ceramics on account of easy control of porosity and pore size and its high thermal stability.

• Steel and Composite Structures
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• v.25 no.4
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• pp.415-426
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• 2017

The thermo-mechanical vibration behavior of two dimensional functionally graded (2D-FG) porous nanobeam is reported in this paper. The material properties of the nanobeam are variable along thickness and length of the nanobeam according to the power law function. The nanobeam is modeled within the framework of Timoshenko beam theory. Eringen's nonlocal elasticity theory is used to develop the governing equations. Using the generalized differential quadrature method (GDQM) the governing equations are solved. The effect of porosity, temperature distribution, nonlocal value, L/h, FG power indexes along thickness and length and are investigated using parametric studies.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.719-722
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• 2003

This paper presents the development of reservoir characterization model equipped with parallelized genetic algorithm, and its application for a heterogeneous reservoir system with integration of the well data and multi-phase production data. A parallel processing method performed by PC-cluster was applied to the developed model in order to reduce time for an inverse calculation. By utilizing the developed model, we performed the inverse calculation with the production data obtained from three layered reservoir system to estimate porosity and permeability distribution. As a result, the pressures observed at well almost identical to those calculated by the developed model. Also, it was confirmed that parallel processing could be applied for reservoir characterization study efficiently.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.12-17
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• 1996

It is true that aggregate strength is usually not a factor in normal concrete strength because, the aggregate particle is several times stronger than the matrix and the transition zone in concrete. In other words, with most natural aggregates the strength of the aggregate is hardly utilized because the failure is determined by the other two phases. But aggregate characteristics that are significant to concrete technology include porosity, grading or size distribution, moisture absorption, shape and surface texture, crushing strength, elastic modulus, and the type of deleterious substances present. Therefore, in the area of high strength concrete, concrete is much more influenced by properties of aggregate. This experiment is performed to investigate how kinds of aggregare influence on the workability of high strength concrete. In this experiment, four types of aggregate is used, that is crushed river aggregate, crushed stone, recycled aggregate of low strength and recycled aggregate of high strength. In this study, we scrutinize a fundmental study on the workability of high strength concrete according to kinds of aggregate.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.85-93
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• 2001

Minimized canister flow restriction and maximized flow uniformity are desired to maximize a purge capability. With the impending ORVR(On Board Refueling Vapor Recovery) systems, the reduction of restriction and increase of flow uniformity in a carbon canister becomes even more critical to meet the stringent regulation. In this study, three-dimensional numerical simulations have been performed to investigate the three-dimensional internal flow patterns in a carbon canister during purge. The effects of the declined angle of the purge pipe and the number of partitions on the pressure drop and purge efficiency in a carbon packed bed are examined. Results show that the purge efficiency and space velocity distribution are affected in the upstream region of 40% of total canister bed by porosity of carbon granule and angle of purge pipe. It is also found that the purge efficiency decreases with increasing the number of partitions.

• Journal of environmental and Sanitary engineering
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• v.11 no.3
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• pp.29-35
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• 1996

Numerical solutions were obtained to the model equations for various parameters characterizing the pore structure, effective internal diffusion and the chemical reaction constant. The conversion was decreased with the cause of pore closure at the surface of reacting particles, reduction of porosity, surface area of reaction and effective diffusion coefficient in the solid with the progress of reaction. Total conversion was strongly depend on the local conversion at surface. According to the decreasing of impregnated concentration of the copper oxide and the increase of the flue gases concentration, total conversion was increased. And the conversion were affected by gas flow rate and pore size distribution of the reacting solid.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.130-133
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• 2005

The effect of microstructural characteristics of A356 alloys on tensile behavior was studied ill the present study. To authors' knowledge, the microstructural effect on mechanical properties of A356 alloy has not been well understood even though this alloy system is one of the most widely used alloys for the industrial purpose. Specially, quantitative relationship between properties like ductility and fracture toughness with microstructural features is lacking. In the present study, three processing routes was used to fabricate samples with different microstructures like size and distribution of primary alpha and eutectic phases. Also, compressive deformation was used to close casting porosity for the cast samples. Tensile behavior was examine and discussed in terms of microstructural aspects.

• Analytical Science and Technology
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• v.5 no.2
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• pp.217-222
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• 1992

An attempt was made to analyze green microstructure of AIN samples prepared by slip casting and dry pressing through Hg-porosimetry. Slip cast samples with narrow pore size distribation and high packing density showed higher sinterability and homogeneous distribution of second phase(s). Hg-porosimetry is and effective way to determine pore structure if "ink bottle" phenomenon does not occur. A comparison study with porosity measurement by quantitative microscopy showed that the effectiveness of Hg-porosimetry measurement could be extended to higher sintered density as long as pores remained open.

• KSBB Journal
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• v.5 no.4
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• pp.397-402
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• 1990

Hydrolysis of inulin was investigated employing various commercially available resin catalysts for the production of high grade fructose syrup. The particle size and porosity of the resin significantly affected the distribution of the products, indicating that the intraparticle diffusion of reactants controls thc selectivity as well as the reaction rate. To confirm the effect of the intraparticle diffusion, two different types of resin catalysts were prepared: the one having sulfonic acid group distributed uniformly throughout genular microparticles (A-type) and the other having sulfonic acid group located mainly at the exterior surface of genular microparticles (E-type). The results were found that the reaction rate and the selectivity of the E-type catalyst were higher than those of the A-type catalyst.