• Weed & Turfgrass Science
• /
• v.3 no.2
• /
• pp.143-149
• /
• 2014

This study was conducted to evaluate the effects of the mixture ratio of soil amendments blended with coco peat (Coco) and American soldier fly cast (SFC) on the physicochemical properties on the sand green. pH and EC of soil were significantly related to mixture ratio of SFC, Mix1, Mix2 and Mix3. Capillary porosity, air-capillary porosity and total porosity of root zone mixed SFC, Coco, Mix1, Mix2 and Mix3 were met to the USGA green specification. The mixture ratios of Mix1 and Mix2 in root zone were positively related capillary porosity and total porosity, and air-capillary porosity was negatively related capillary porosity and hydraulic conductivity. Capillary porosity of Mix1, Mix2 and Mix3 blended SFC and Coco was affected by SFC and Coco, and total porosity by Coco. These results showed that soil amendments blended SFC and Coco was developed capillary porosity and hydraulic conductivity on the USGA sand green than these of SFC.

• Transactions of Materials Processing
• /
• v.14 no.3 s.75
• /
• pp.224-232
• /
• 2005

The high-pressure die-casting is one of the most effective methods to produce a large amount of products in short cycle time. This process, however, has a problem that the gas porosity defect appears easily. The generation of gas porosity is known mainly due to the air entrapment during the injection stage. Most of numerical simulations for the molten metal flow pattern observations have done in the treating of one phase fluid flow but the gas-liquid interface is essentially multi- phase phenomenon. In this paper, the two-phase fluid flow numerical simulation methods have been adapted to predict the gas porosity generations in the molten metal. The accuracy and the usefulness of the new simulation module have been emphasized and verified through some comparison experiments.

• Journal of Ocean Engineering and Technology
• /
• v.13 no.3B
• /
• pp.29-37
• /
• 1999

Ventilation of the marine engine room is very important for the health of the workers as well as the normal operation of machines. To find proper ventilation conditions of this engine room, numerical simulation with standard k-${\epsilon}$ model was carried out. In the present study, the marine engine room is separated to two floors with porus horizontal partition and considered as a closed space with a heat source and forced ventilation ducts. The porosity of horizontal partition is found to be important. For the engine room with 2 supply ports & 2 exhaust ports, the increasing of the porosity of horizontal partition is effective to reduce the recirculation flow zone in the second floor. When the engine room is ventilated with three supply air ports & one exhaust port, the increasing of the porosity of horizontal partition is effective to reduce the recirculating flow zone in the exhaust air area, but there is a possibility of local extreme heating at the lower side of engine near bottom.

• Fashion & Textile Research Journal
• /
• v.3 no.1
• /
• pp.15-19
• /
• 2001

The purpose of this study was to determine the thermal characteristics of men's suits ensembles and their fabrics. For the study, 100% wool fabrics were woven with various fabric structure, fabric density and yam count and With the use of these, 12 men's suits were made with the same design. Physical characteristics that affect thermal transport properties, including drapery, cover factor; bulk density, keeping warmth ratio, vapor permeability, air permeability and porosity of the fabrics were measured. In addition, thermal resistance of men's suit ensembles, including Y-shirts, inner wear and socks was measured on the thermal manikin in the environmental chamber. The result of the study was as follows: 1. In terms of fabric structure, keeping warmth ratio of plain woven fabrics was higher than those of twill and satin woven fabrics and also, vapor and air permeability and porosity of plain woven fabrics were higher than those of twill and satin woven fabrics. 2. The result showed that thermal resistance of 12 ensembles were in the range of 0.77clo~0.97clo. 3. There was little correlation between woven condition such as, including structure, fabric density and yam count and thermal resistance of ensembles.

• The Journal of Engineering Geology
• /
• v.14 no.2
• /
• pp.169-177
• /
• 2004

The permeation movements of groundwater recharge and contaminate materials receive a eat effect due to porosity and effective porosity of porous media which is composing underground consisted of saturation and unsaturated states. This study developed Frequency Domain Reflectometry(FDR) system and measurement sensor, and then carried out the laboratory experiments to measure effective porosity for unsaturated porous media. Also, I suggested dielectric mixing models(DMMs) which can calculate the effective porosity from relation of measured dielectric constants. In the experimental results the extent range of effective porosity of standard sand and river sand which are unsaturated soil sample were measured in about 65∼85 % for porosity. In relation of effective porosity and porosity, especially, effective porosity confirmed that displays decreasing a little tendency as porosity increases. This is because unsaturated soil did not reach in saturation enough by air of very small amount that exist in pore between soil particles.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2004.05a
• /
• pp.33-37
• /
• 2004

Recently, Growing tendency for structure surface to use water repellent agent has increased steadily. But investigation of it's protection and durability property is not sufficient. Therefore, this paper shows the investigation about repellent property and micro structure's change in surface layer of mortar that is applied by water repellent agent. Water repellent property, absorption coefficient, air permeability, porosity and observation of micro construct was investigated according to water repellent agent type. The test results indicated that mortar applied water repellent agent appears tiny absorption coefficient, but air permeability is maintained. The reason is because silane solution is coating at capillary surface of a wall and minute pore structure is changeless.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2002.05a
• /
• pp.31-36
• /
• 2002

Recently, more interests in surface treatment of structure with water repellent agent are steadily increased, But, investigation of its properties such as protection, durability, morphology of micro structure is not sufficient. Therefore, This paper is aimed for the investigation of water repellent property and change of morphology of micro pores in mortar that is treated by water repellent agent(Inorganic polymer based material). Water repellent property, water absorption coefficient, air permeability, porosity and the observation of micro structure was investigated in different water repellent agent type. The test results indicated that water repellent treated mortar showed low absorption coefficient and air permeability(breathing effect). This is why inorganic polymer is coated at the wall of capillary and micro pores, also, the volume of micro pore is reduced without the change of morphology in micro structure.

• Journal of Soil and Groundwater Environment
• /
• v.15 no.6
• /
• pp.91-98
• /
• 2010

The effective thermal conductivity of porous materials is usually determined by porosity, water content, and the conductivity of the matrix. In addition, it is also affected by the internal structure of the materials such as the size, arrangement, and connectivity of the matrix-forming grains. Based on the structural models for multi-phase materials, thermal conductivities of soils and sands measured with varying the water content were analyzed. Thermal conductivities of dry samples were likely to fall in the region between the Maxwell-Eucken model with air as the continuous phase and the matrix as the dispersed phase ($ME_{air}$) and the co-continuous (CC) model. However, water-saturated samples moved down to the region between the $ME_{wat}$ model and the series model. The predictive inconsistency of the structural models for dry and water-saturated samples may be caused by the increase of porosity for water-saturated samples, which leads to decrease of connectivity among the grains of matrix. In cases of variably saturated samples with a uniform grain size, the thermal conductivity showed progressive changes of the structural models from the $ME_{air}$ model to the $ME_{wat}$ model depending on the water content. Especially, an abrupt increase found in 0-20% of the water content, showing transition from the $ME_{air}$ model to the CC model, can be attributed to change of water from the dispersed to continuous phase. On the contrary, the undisturbed soil samples with various sizes of grains showed a gradual increase of conductivity during the transition from the $ME_{air}$ model to the CC model.

• Journal of the Korean Ceramic Society
• /
• v.52 no.6
• /
• pp.467-472
• /
• 2015

The effect of $SrCO_3$ content on the microstructure, porosity, flexural strength, and pore size distribution of clay-based membrane supports was investigated. Green compacts prepared from low cost materials such as kaolin, bentonite, talc, sodium borate, and strontium carbonate were sintered at $1000^{\circ}C$ for 8 h in air. It was possible to control the porosity of the clay-based membrane supports within the range of 33% to 37% by adjusting the $SrCO_3$ content. The flexural strength of the clay-based membrane supports was found to strongly depend on their porosity. In turn, the porosity was affected by the $SrCO_3$ content. The average pore size and flexural strength of the clay-based membrane supports containing 4 wt% $SrCO_3$ were $0.62{\mu}m$ and 33 MPa at 34% porosity.

• Journal of the Korean Ceramic Society
• /
• v.25 no.5
• /
• pp.532-540
• /
• 1988

Even the finest cement as having a specific surface area of 6.000~8.500$\textrm{cm}^2$/g (Blaine) is to convert into low-porosity hardened cement paste by the use of appropriate plasticizer. In this study, tests were carried out on such a special cement mix(fineness of 6.000$\textrm{cm}^2$/g, Ca-lignosulfonate plus k2CO3 as plasticizer and W/C=0.25) in comparison with ordinary Portland cement. Owing mainly to the high fineness of the cement powder and the low water-to-cement ratio, the hardened low-porosity cement paste showed a very tight microstructure, the pore texture of which consisted of micropores and wide pores only of small radii. The consequence of such mix was hence that the low-porosity special cement had excellent properties of early-high and very high strengths as compared to ordinary Portland cement. Its volume change when dried in the air or re-wetted, exhibited superor behaviour as well.