• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.217-218
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• 2023

This study is to develop porous concrete using super absorbent polymer, which possesses insolubility and high absorption capacity, as a substitute material for lightweight soil. Various mixtures were prepared using aggregates, cement, mixing water, and super absorbent polymer, and the absorption ratio and compressive strength were examined for each mixture. As the amount of super absorbent polymer added increased, the absorption ratio also increased, reaching up to 35-105%. However, the compressive strength decreased by 49.5% to 65.3%. This is believed to be due to the inherent properties of super absorbent polymer, which led to an increase in the absorption ratio but, in turn, reduced the binding strength of cement paste particles, resulting in a decrease in compressive strength.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3232-3237
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• 2013

This study was carried out to evaluate the economic value of Tyvek planting technique in Korean citrus. The Tyvek planting technique was developed by national institute of horticultural and herbal science in Korea rural development administration. This technology could be used to improve efficiency and practicality of cultivation of citrus. The research results show that the technological value of Tyvek planting technique was evaluated 42,163(discount rate 6%)-55,018(discount rate 8%) million won. IRR is greater than discount rate(6-10%). NPV is greater than zero. B/C ratio IRR is greater than 20. The economic validity of Tyvek planting technique is identified by the results of technology evaluation.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.150.1-150
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• 2003

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.62-68
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• 2004

In this study, SHS process has been employed to fabricate porous $MoSi_2$ material with electric-resistive heating capability through the control of pore size. The preform for SHS reaction was consisted of molybdenum powder with different sizes and silicon powder with different contained quantity. The size of the $MoSi_2$ particles thus formed was determined by the generated heat of combustion, not by the size of molybdenum powder. However, the pore size of $MoSi_2$ composite was proportional to the particle size of molybdenum powder. that is the coarser the molybdenum powder used, the larget the formed pore size. Based on these results, the porous $MoSi_2$ composite could be fabricated with a desired pore size. By orienting the porous molybdenum disilicide-based material in the form of pore size gradient, porous materials used for filters with improved dirt-holding capacity can be manufactured.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2007.11a
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• pp.291-292
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• 2007

• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.449-454
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• 1998

It is well known that new tissue or blood vessel is grown into a porous calcium phosphate ceramics used as a bone graft substitute due to their excellent biocompatibility. In this study, the most chemically stable porous $\beta$-crystalline form in various forms of calcium metaphosphate, Ca(PO$_3$)$_2$is prepared by the controlled thermolysis of monocalcium phosphate, Ca(H$_2$PO$_4$)$_2$.The diameter of cylindrical pores formed during cooling was controlled by a holding time at the melting point of a monocalcium phosphate and by the change of a crystallization temperature, to obtain the most appropriate size (about 200$\mu$m) of pores for the application of bone substitutes and matricuts. It was observed that the increasing holding time at the melting point of monocalcium phosphate results in the decreases of cylindrical pore sizes.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.5
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• pp.399-405
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• 2010

The accumulated displacements and fatigues of rock are increased by the stress-hysteresis, induced from repeated frost-thawing. Also the shear strength is decreased by them continuously. The stress-hysteresis is affected by the atmospheric temperature changes, whose behavior is visco-elasticity, usually. Therefore, to do ideal body analysis, Kelvin model could be used to analyze the frost-thawing behavior in winter. In general, rock slope failure occurs by the deterioration of rocks, which is caused by the repetition of freezing-thawing process. In order to keep the safety of such rock mass structures the deterioration process of rock needs to be described quantitatively using some meaningful parameters. In this work, the deterioration process in freezing-thawing cycle of tuff, which is a famous soft porous rock, is investigated through laboratory tests and successfully described as a differential equation for the change of porosity. And then, the deterioration of the mechanical properties of rock, such as Young's modulus and uniaxial compressive strength, are quantitatively described as a function of the porosity.

• Journal of computational fluids engineering
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• v.13 no.2
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• pp.62-67
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• 2008

This study aims to investigate numerically the static stiffness characteristics of porous air bearing and to estimate appropriate permeability values of porous medium. In particular, a new roughness model is proposed and implemented into the commercial CFD code (FLUENT Ver. 6.2) by using C language based user subroutine. The predicted results are extensively compared with experimental data. The roughness model is also validated through comparison with the results from open literature. It is found that the predictions for static stiffness are in good agreement with experimental data. Therefore, the suggested model based on the roughness Reynolds number can be used in studying the stiffness characteristics of porous air bearing effectively. In addition, numerical simulations of various diameter size and conditions are conducted. According the results, it is expected that the static stiffness of porous air bearing has the non-linear characteristics.

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.59-63
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• 2004

In recent days. it is necessary to find environment-friendly way of diposing industrial waste and reclying system. So this study will analyze the property of Porous concrete improved by concrete waste powder and recycled lightweight aggregate and then suggest the ways of reclying. The method deals with experimenting unit weight of capacity. thermal conductivity, compression and ultrasonic pluse velocity. Considering the relation between ultrasonic pluse velocity and unit weight & thermal conductivity through the graph. the result of relation between ultrasonic pluse velocity and unit weight & thermal conductivity on the graph expessed their high interaction shown as direct proportion on the graph. Recycled Porous concrete merits lightweight and adiabatic. Therefore. we will expect that the current using ALC and Recycled Porous concrete has be similar thermal conductivity.

• Electrical & Electronic Materials
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• v.10 no.9
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• pp.916-921
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• 1997

In this study Characteristics of 3-D underwater object recognition independent of translation using the self-made ultrasonic sensor fabricated with porous piezoelectric resonator and presented. The sensor was satisfied with requirement of ultrasonic sensor. The recognition rates for the training data and the testing data are 97.45 and 91.25[%] respectively using the self-made ultrasonic sensor and SCL(Simple Competitive Learning) neural network. According to the experimental results It is believed that the self-made ultrasonic sensor can be applied as sensor of SONAR system.