• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.2 s.25
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• pp.127-135
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• 2006

Experimental studies of the cylindrical sintered-copper wick heat pipes were carried out to investigate the capillary heat transfer characteristics. Six models of the sintered-copper wick heat pipes were manufactured and tested to evaluate the heat transport limitations and the thermal characteristics. Also the performance of the heat pipes was analyzed theoretically and compared with the test results. The heat pipe models are divided into two sintered-wick groups and the nominal particle sizes are $180{\mu}m$(wick #1) and $200{\mu}m$(wick #2) respectively The experimental results showed that, the porosity of wick #1 was higher than that of wick #2, and also the wick #1 was generally superior than the wick #2 for the heat transport capability. The maximum heat transport rates were increased as the wick thicknesses and the vapor temperatures were increased.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.229-238
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• 2017

This study started to deduce a permeability relationship that can consider the geometric features of various porous media under different flow regimes. With reference to the previous works of Kozeny and Carman, the conventional Darcy-Weisbach relation (Darcy's friction flow equation) was reviewed and expanded for porous flow analysis. Based on the capillary model, this relation was transformed to the friction equivalent permeability (FEP) definition. The validity of the FEP definition was confirmed by means of comparison with the Kozeny-Carman equation. Hereby, it was shown that the FEP definition is the generalized form of the Kozeny-Carman equation, which is confined to laminar flow through a circular capillary. In conclusion, the FEP definition as a new permeability estimation method was successfully developed by expanding the Darcy-Weisbach relation for porous flow analyses.

• Journal of the Korean Wood Science and Technology
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• v.36 no.5
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• pp.49-55
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• 2008

This study was carried to investigate the effects of steaming and four different drying methods on the longitudinal liquid permeability of Korean pine (Pinus koraiensis Sieb.et Zucc.) board. Four drying methods were air drying, conventional kiln drying, microwave-vacuum drying and high temperature drying. Darcy equation was used for calculating the specific permeability of the small sapwood specimens taken from the treated boards while capillary rising method was used for the heartwood specimens. The sapwood specimens were extracted with water and benzene-alcohol solution to examine the mechanism of liquid flow in treated wood. No significant correlation was found between specific permeability and the number of resin canals of the sapwood specimens. Extraction decreased the differences of specific permeabilities of the sapwood specimens between the five treatment methods. The effects of extraction on the longitudinal permeability are different between five treatments. The fluid path in heartwood was observed by dynamic observation method.

• Journal of Yeungnam Medical Science
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• v.29 no.2
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• pp.145-149
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• 2012

Systemic capillary leak syndrome (SCLS) is an unusual entity characterized by hypovolemic shock, hemoconcentration, and hypo-albuminemia associated with paraproteinemia as a result of marked capillary hyper-permeability. Complications of this syndrome can include compartment syndromes, pulmonary edema, thrombosis, and acute kidney injury. This paper reports a case of severe SCLS accompanied by acute tubular necrosis caused by hypoperfusion and myoglobinuria secondary to rhabdomyolysis, which resulted in chronic kidney disease that necessitated hemodialysis. However, there have been rare data of residual end-organ damage after acute attacks in Korea. Therefore, this paper reports a case of complicated SCLS enough to hemodialysis and that developed into chronic kidney disease.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.97-103
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• 2005

In this paper, effects on the heat transport limitation of heat pipe by the wick structural factors were theoretically analyzed for the sintered-copper wick heat pipe. Uniformity of particle size and sintering process were acted as dominant factors on the pore distribution and wick porosity, and small deviations of the wick thickness and the pore size greatly affected the heat transport limitations of the heat pipe. Especially, slight variations of the wick thickness, mean particle radius and capillary radius along the vapor temperatures and inclination angles remarkably changed the capillary limitation of the heat pipe.

• Journal of Energy Engineering
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• v.13 no.4
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• pp.267-274
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• 2004

Theoretical analysis for predicting the heat transport limitations of screen mesh wick and sintered wick heat pipes was performed. The heat pipe diameter was 8mm and water was used for working fluid. For the 250 mesh, each capillary pressures and heat transport limitations, thermal resistances were analyzed according to the operating temperatures, wick thicknesses and inclination angles, based on the effective capillary radius (r$\_$c/), porosity ($\varepsilon$) and permeability (K). The wick capillary limitation was increased as the operating temperature and the wick thickness were increased, and generally the sintered wick showed higher heat transport limitations than that of the screen wick. The thermal resistance of the screen wick was higher than that of the sintered wick and both thermal resistances were linearly increased as the wick thickness was increased.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.947-961
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• 2017

An innovative spiral variable-section capillary model is established for piping critical hydraulic gradient of cohesion-less soils causing water/mud inrush in tunnels. The relationship between the actual winding seepage channel and grain-size distribution, porosity, and permeability is established in the model. Soils are classified into coarse particles and fine particles according to the grain-size distribution. The piping critical hydraulic gradient is obtained by analyzing starting modes of fine particles and solving corresponding moment equilibrium equations. Gravities, drag forces, uplift forces and frictions are analyzed in moment equilibrium equations. The influence of drag force and uplift force on incipient motion is generally expounded based on the mechanical analysis. Two cases are studied with the innovative capillary model. The critical hydraulic gradient of each kind of sandy gravels with a bimodal grain-size-distribution is obtained in case one, and results have a good agreement with previous experimental observations. The relationships between the content of fine particles and the critical hydraulic gradient of seepage failure are analyzed in case two, and the changing tendency of the critical hydraulic gradient is accordant with results of experiments.

• Advances in concrete construction
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• v.13 no.1
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• pp.101-111
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• 2022

The rapid development of the construction industry in the world causes a rapid increase in the consumption of aggregate resources, which leads to the depletion of existing aggregate reserves. The use of recycled aggregate in the production of concrete and mortar may be a good solution to reduce the use of natural raw materials and to reduce demolition waste in the environment. In this study investigating the use of recycled aggregate in mortar production, mortar mixtures were produced by substituting 0%, 25%, 50% and 100% fine recycled aggregate (FRA) instead of natural aggregate. The effect of 20% and 40% fly ash (FA) substitutes on cement mortar performance was also investigated. Compressive and flexural strength, drying shrinkage, abrasion resistance, water absorption and capillary water absorption were investigated on the produced mortars. The increase in the use of FRA reduced the compressive and flexural strengths of mortars. While the capillarity coefficients, water absorption, rapid chloride permeability and drying shrinkage of the mortars increased with the increase in the use of FRA, the effect of the use of fly ash on the rate of increase remained lower. The increased use of FRA has improved abrasion resistance as well.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.33-37
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• 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
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• 2002.05a
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• pp.31-36
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• 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.