• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.473-478
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• 2015

Green bodies of earthenware tile were prepared from a mixture of earthenware tile powder and SiC as forming agents by applying a conventional process. Granule powder for tile samples was prepared using the spray drying method with commercial earthenware raw material with a quantity of SiC of 0.3 wt%. The applied pressure was $250kg{\cdot}f/m^2$ and the firing temperature was $1050-1200^{\circ}C$. The effects of the SiC particle size and sintering temperature on the open porosity and total porosity were investigated and the correlative mechanism was also discussed. While total porosity was not significantly changed by decreasing the SiC particle size, the open porosity showed a gradual decrease, which represents an increase of the closed porosity. As the sintering temperature increased, coarsening was made among the pores due to excessive oxidation. The volume shrinkage and bending strength were demonstrated for the sintered tile samples. The sintered bulk density was also measured to determine the weight reduction value.

• Korean Journal of Food Science and Technology
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• v.38 no.2
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• pp.215-221
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• 2006

This study focuses on investigating the effect of porosity-controlled earthenware on fermentation of kanjang, Korean soy sauce. Porosity of fermentation vessel was controlled by changing the mixing ratio of raw soils at manufacturing earthenware. Earthenwares contented 0%, 40% and 60% of the mixture of red brown soil and powdered soil (1 : 1), respectively. The more contents of the mixed soil, the more porosity in earthenware. During fermentation of kanjang in porosity-controlled earthenwares at $30^{\circ}C$ for 4 months, physical, chemical, microbiological and sensory quality attributes were monitored. Compared to other containers, kanjang in the earthenware that had 0% mixed soil showed less water loss, salt content and pH. It also produced higher total acidity, protease activity, total nucleotide, and microbiological changes which included total aerobic bacteria, lactic acid bacteria and yeast. Total nitrogen and free amino acids in kanjang did not show the consistency with the mixed soil contents of fermentation containers, which may take more effect of other factors as water loss than the porosity of vessels. However, the percentage of glutamic acid in total free amino acids was a little higher in the earthenware that had 0% of mixed soil than other containers. These positive physicochemical, microbiological changes also resulted in higher sensory quality.

• The Journal of the Petrological Society of Korea
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• v.20 no.3
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• pp.141-149
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• 2011

Samples (two granites, marble, sandstone) were heated in an electric furnace at temperature $400^{\circ}C$ and $600^{\circ}C$ in order to investigate the change of physical properties of rocks depending on the heating temperature. Changes of Color and physical properties such as specify gravity, porosity, absorption, p-wave velocity are visible while mineralogical changes by using polarizing microscope are not pronounced. In addition, porosity and absorption increased while specific gravity and p-wave velocity decreased at a more higher temperature ($600^{\circ}C$). Although the open porosity does not indicate total porosity of the rock. but p-wave velocity can be used to evaluate the degree of damage Therefore, porosity and p-wave velocity should be compared in order to investigate the change of physical properties of rocks depending on the heating temperature.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.4
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• pp.52-62
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• 2015

This study estimated the contribution rates of inlet air flow, moisture content, air-filled porosity and particle size on the total pressure drop for the sawdust used as the bulking agent in the composting. The statistical model for pressure drop including the affecting factors was proposed.($R^2=0.998{\sim}0.950$) While the laminar air flow(v) and particle size(SIZE*v) had the positive relations to the total pressure drop, the turbulent air flow($v^2$), moisture content(MC*v) and air-filled porosity(AFP*v) had the negative relations. Total pressure drop sharply increased with increasing of the inlet air flow. And the most significant factors affecting to total pressure drop were the particle size(SIZE*v) as positive factor and air-filled porosity(AFP*v) as negative factor. The contribution rate to total pressure drop by the particle size(SIZE*v) was continuously increased with increasing of the inlet air flow, but the contribution rate by air-filled porosity(AFP*v) was decreased. And total pressure drop was little changed even though the increasing of moisture content above the range of dry moisture content 0.25. The contribution rates of affecting factors had the different tendencies with increasing of the moisture content, especially in the negative factors as air-filled porosity(AFP*v) and moisture content(MC*v). For effective composting process, it is preferable to select the sawdust with higher air-filled porosity as bulking agent to enhance the air permeability.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.538-543
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• 2003

Perforated wall has long been employed to control a variety of flow phenomena. It has been, in general, characterized by a porosity of the perforated wall. However, this porosity value does not take account of the number and detailed shape of porous holes, but is defined by only the ratio of the perforated area to total wall surface area. In order to quantify the porous wall effects on the flow control performance, an effective porosity should be known with the detailed flow properties inside the porous holes. In the present study, a theoretical analysis using a small disturbance method is performed to investigate detailed flow information through porous hole and a computational work is also carried out using the two-dimensional, compressible Navier-Stokes equations. Both the results are compared with existing experimental data. The gasdynamical porosity is defined to elucidate the effect of perforated wall.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.159-162
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• 1999

The paper presents results of an investigation on the permeability characteristics and pore structure of concrete containing different levels of fly ash, silica fume, or blast furnace slag. The total cementitious content was 351kg/㎥, and the water/cementitious materials ratio was 0.55. The porosity and pore structure of representative pastes of the matrix were measured using mercury intrusion porosimetry, and the permeability characteristics of concrete were also determined by water and oxygen permeability, chloride ion penetration. The results show that significant reduction in permeability of concrete containing pozzolanic materials due to formation of a discontinuous macro-pore system which inhibits flow. And, the permeability of concrete and pore structure(capillary porosity or total porosity) shows linear relationship.

• Environmental Engineering Research
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• v.12 no.3
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• pp.109-117
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• 2007

The characteristics of carbonaceous particles collected from the combustion of Vacuum Residue (VR) in a test furnace have been investigated. The physical and chemical characterization includes particle size, scanning electron microscopy of the surface structure, measurement of porosity, surface area and density, EDX/XRD analyses and measurement of chemical composition. The studies show that the carbonaceous VR particles are very porous and spheroidal, and have many blow-holes on the surface. The particles become smaller and more sponge-like as the reaction proceeds. The present porosity of VR particles is similar to that of cenospheres from the combustion of heavy oil, and the majority of pores are distributed in macro-pores above $0.03\;{\mu}m$ in diameter. Measurements of pore distribution and surface area showed that the macro-pores contributed most to total pore volume, whereas the micro-pores contributed to total surface area.

• Structural Engineering and Mechanics
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• v.76 no.1
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• pp.27-56
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• 2020

In this paper, the deflection and buckling analyses of porous nano-composite piezoelectric plate reinforced by carbon nanotube (CNT) are studied. The equations of equilibrium using energy method are derived from principle of minimum total potential energy. In the research, the non-local strain gradient theory is employed to consider size dependent effect for porous nanocomposite piezoelectric plate. The effects of material length scale parameter, Eringen's nonlocal parameter, porosity coefficient and aspect ratio on the deflection and critical buckling load are investigated. The results indicate that the effect of porosity coefficient on the increase of the deflection and critical buckling load is greatly higher than the other parameters effect, and size effect including nonlocal parameter and the material length scale parameter have a lower effect on the deflection increase with respect to the porosity coefficient, respectively and vice versa for critical buckling load. Porous nanocomposites are used in various engineering fields such as aerospace, medical industries and water refinery.

• Atmosphere
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• v.17 no.4
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• pp.315-326
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• 2007

The effects of windbreaks on the reduction of suspended particles are investigated using a computational fluid dynamics (CFD) model with the ${\kappa}-{\varepsilon}$ turbulence closure scheme based on the renormalization group (RNG) theory. In the control experiment, the recirculation zones behind the storage piles are generated and, as a whole, relatively monotonous flow patterns appear. When the windbreaks with the 0% porosity are constructed, the recirculation zones are generated by the windbreaks and very complicated flow patterns appear due to the interference between the windbreaks and storage piles. The porosity of the windbreaks suppresses the generation of the recirculation zone and decreases the wind velocity in the windbreaks as well as that outside the windbreaks. As the emission of suspended particles from the storage piles are closely related with the friction velocity at the surfaces of the storage piles, variation of the friction velocity and total amount of the emission of the suspended particles with the height and porosity of the windbreaks are investigated. The results show that higher and more porous windbreaks emit less suspended particles and that the reduction effect of the porosity is still more effective than that of the height. In the case of the windbreak with 30 m height and 50% porosity, friction velocities above the storage piles are smaller than the critical friction velocity above which particles would be suspended. As a result, total amount of suspended particles are much fewer than those in other cases.

• Korean Journal of Environmental Agriculture
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• v.41 no.2
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• pp.101-107
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• 2022

BACKGROUND: Soil amendment was necessary applied for the sand that had been used to root zone of green ground in golf course because of its low water retention power and cation exchangeable capacity. This study was conducted to evaluate the effect of the mixed ratio of peat moss and coconut coir as soil amendment materials on the soil physicochemical properties applied to rootzone based on sand. METHODS AND RESULTS: The soil amendments were blended at 0, 3, 5, 7 and 10% by soil volume. The pH in the peat moss treatment was lower than that of control (0% soil amendment), and pH and electrical conductivity (EC) in the coconut coir were higher. The blending ratio of peat moss was negatively correlated with pH of rootzone soil (p<0.01), and that of coconut coir positively with EC (p<0.01). As compared with control, capillary porosity, the physical factors such as air-filled porosity, total porosity, and hydraulic conductivity of rootzone soil were increased by applying peat moss and coconut coir. For correlation coefficients between percentage of soil amendments and soil physical factors, peat moss and coconut coir were positively correlated with porosity and hydraulic conductivity (p<0.01). CONCLUSION(S): These results indicated that the application of peat moss and coconut coir affected on the change of physicochemical properties of rootzone soil, and improved soil porosity and hydraulic conductivity.