• Journal of the Korean Ceramic Society
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• v.49 no.4
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• pp.347-351
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• 2012

Vermiculite-silica composites with a layered structure were fabricated by adding cellulose fibers as a pore former and by a simple uniaxial pressing and subsequent sintering process. Three different combinations of additives were used and their effects on the compressive strength and thermal conductivity of the composites were investigated. Both compressive strengths (42-128 MPa) and thermal conductivities (0.75-1.48 $W/m{\cdot}K$) in the direction perpendicular to the pressing direction (T) were higher than those (19-81 MPa and 0.32-1.04 $W/m{\cdot}K$) in the direction parallel to the pressing direction (S) in all samples. The anisotropy in both properties was attributed to the microstructural anisotropy, which was caused by the layered structure developed in the composites.

• Journal of the Korean Ceramic Society
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• v.49 no.3
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• pp.226-230
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• 2012

This paper presents a novel structure for a diesel particulate filter (DPF) with inclined gas paths, which was designed so that the gas paths offered a fluent flow of exhaust gases, and particulate matter (PM) was collected at pores formed in the body. The alumina porous filter was prepared by a conventional sintering process at $1200^{\circ}C$ for 2 h. Straight gas paths with $30^{\circ}$ of inclination from the gas flow direction were formed in the filter body. It is shown that this filter structure worked as a PM filter, in which 90.2% of soot filtration efficiency and 59.6 mbar of pressure drop were achieved.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.99-105
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• 1993

The purpose of this fundamental study is to investigate the mechanism of high strength concrete using the high calcium sulfate cement from a point of view in cement hydration and micro structure. As a results, it was found that the internal pores of concrete are decreased by using the high calcium sulfate cement, because the hydrates of Ettringite which is densified in structure is much formed in early ages at steam curing. In addition to the ettringite needs the 32 times of free water formed mixing water for hydration. This effect are not only decreased the water to cement ratio and also increase to comp, strength of concrete. It was conclude that these above the two facts are the main mechanism of high strength concrete using high calcium sulfate cement.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.2
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• pp.47-53
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• 2004

In this experiment the effects of the packing structure of pigment on the surface characteristics (smoothness and gloss) of coated paper are studied. Four different kinds of inorganic pigments(clay), ground calcium carbonate(GCC), two of precipitated calcium carbonates(PCC), and two organic pigments(solid bead and hollow type) were used. The method of measuring the relative sediment volume(RSV) was used to analyze the packing structure of coating layer. The relative sediment volume was measured, using the pressure dewatering dry-cake method(PDDM) and centrifuge method. Also, the particle size distribution of coating pigment was determined. The results showed that small amount of organic pigment, added to inorganic pigment, improved smoothness and its effect was greater when GCC was used as inorganic pigment. The efficiency of organic pigment depended upon the inorganic pigment since the organic pigment is packed in the pores formed by the inorganic pigment.

• Transactions of Materials Processing
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• v.11 no.8
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• pp.701-709
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• 2002

Aluminium foam material is highly porous material, which has the complicated cellular structure defined by randomly distributed pores in metallic matrix. This structure gives the characteristic properties which cannot be achieved by any other conventional processes. As the properties of aluminium foam material significantly depend on its porosity, a desired profile of properties can be tailored by changing the foam density. But various defects lead to undesirable effects on the mechanical properties. Mechanical properties are dependent on cell sizes and aspect ratios. Therefore, this paper presents the effects of various processing parameters of various parameters on the mechanical properties. For the sake of this, combined stirring was used to fabricate aluminum foam materials by the parameters. Compression and bending tests were performed to investigate the effects of cell sizes and aspect ratios on the mechanical properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.9
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• pp.801-806
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• 2003

In recent years, there has been large interest in the fabrication of the self organized nanoscale structures since not only their potential utilization in electronic, optoelectronic, and magnetic devices but also their fundamental interest such as uniformity and regularization. An attractive candidate of these materials is anodic porous alumina film(Al$_2$O$_3$) which is formed by the anodization of aluminum in an appropriate acid solution. In this study to fabricate the porous alumina film with very uniform and nearly parallel pores the anodization was carried out under constant voltage mode in 0.3M oxalic acid as an electrolyte. The hexagonally ordered arrays with a few $\mu\textrm{m}$ in size two-dimensional polycrystalline structure were obtained of which pore densities were 1.1${\times}$10$\^$10//$\textrm{cm}^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.629-632
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• 1999

For replacing Li metal ai Lithium ton Bakery(LIB) system. we used carbon powder material which prepared by pyrolysis of phenol resin as starting material. It became amorphous carbon by pyrolysis through it\`s self condensation by thermal treatment. Amorphous carbon can be doped with Li intercalation and deintercalation because it has wide interlayer. however it has a problem with structural destroy causing weak carbon-carbon bond. So. we used ZnCl$_2$ as the pore-forming agent. This inorganic salt used together with the resin serves not only as the pore-forming agent to form open pores, which grow Into a three-dimensional network structure in the cured material, foul also as the microstructure-controlling agent to form a loose structure dope with bulky dopants. We analyzed SEM in order to find to different of structure. and can calculate distance of interlayer. CV test showed oxidation and reduction

• Computers and Concrete
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• v.10 no.3
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• pp.219-229
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• 2012

Carbonation is a widespread degradation of concrete and may be coupled with more severe degradations. An experimental investigation was carried out to study the effect of carbonation on chloride ion diffusion of concrete. The characteristic of concrete after carbonation was measured, such as carbonation depth, strength and pore structure. Results indicated that carbonation depth has a good linear relation with square root of carbonate time, and carbonation can improve compressive strength, but lower flexural strength. Results about pore structure of concrete before and after carbonation have shown that carbonation could cause a redistribution of the pore sizes and increase the proportion of small pores. It also can decrease porosities, most probable pore size and average pore diameters. Chloride ion diffusion of concrete after carbonation was studied through natural diffusion method and steady state migration testing method respectively. It is supposed that the chloride ion concentration of carbonation region is higher than that of the sound region because of the separation of fixed salts, and chloride ion diffusion coefficient was increased due to carbonation action evidently.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.27-37
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• 2007

The purpose of this study is to propose a method to predict the minimum curing time of early age concrete required to prevent frost damage. Tests were performed to examine major factors, which affect the compressive strength of concrete frozen at early ages and investigate the source of frost damage at early age concrete. The results from the tests showed that the loss rate of compressive strength decreases as the beginning time of frost damage was delayed and water-cement ratio was lower. In addition, the test results also showed that concrete made with type III cement was less susceptible to frost damage than concrete made with ordinary Portland cement and frost damage occurred through the formation of ice lenses. When early age concrete is being damaged by frozen, a phase transition into ice of free water presented at the capillary pores of the concrete gives a reason for the decrease of compressive strength. Accordingly, the frost resistance of fresh concrete can be determined based on the saturation degree of the capillary pores. The method to predict the minimum curing time was suggested using the concept of critical saturation degree of the capillary pores.

• Journal of Environmental Science International
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• v.20 no.6
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• pp.729-736
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• 2011

This work is to compare the experiment results by a continuous fixed-bed adsorption of water vapor, acetone vapor, and toluene vapor on zeolite 13X (SAU) and silica-alumina (SAK). SAU and SAK have very different pore structure but similar composition as inorganic adsorbent. The relationship between the equilibrium adsorption capacity and specific pore size range were studied. Adsorption of water vapor was more suitable on SAU than SAK because SAU has relatively more developed pores around $5\;\AA$ than SAK in the pore range of $10\sim100\;\AA$. Adsorption of acetone vapor was more suitable on SAK than SAU because SAK has relatively more developed pores around $5\sim10\;\AA$ than SAK in the pore range of less than $10\;\AA$. Adsorption of toluene vapor was more suitable on SAK than SAU because SAK has relatively more developed pores in the pore range of $10\sim100\;\AA$ than SAK. Adsorption capacity of the adsorbent was closely related to the surface area generated in the specific pore size region. But it was difficult to distinguish the relationships between adsorption capacity and micro area, and the external surface area of adsorbent.