• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.44-48
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• 2004

A silent type ozone generator using water surface electrode was proposed. And it was investigated experimentally that a variation of water conductivity affected to water surface discharge. Important factors affecting to water surface discharge are ions in discharge space and ions and polarized molecules in water and so on. In this study, It was intended to change the characteristics of discharge by controlling the number of ions in water. The number of ions in water could be controlled by changing the water conductivity. Water conductivity was controlled by quantity of inserted NaCl to distilled water. At this time, current-voltage characteristics and characteristics of ozone generation quantity were investigated in each case. As a result, when NaCl was inserted in distilled water, more stable discharge was generated. As the quantity of NaCl was increased, discharge starting voltage could be lowered.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.12
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• pp.1126-1133
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• 2004

This paper presents an experimental measurement of effective thermal conductivity in an adsorbent packed bed with silica gel A type. The effective thermal conductivity was measured under different conditions of the adsorbent bed temperature, pressure, particle size and water content by using the transient hot wire method. The measured effective thermal conductivity showed to become bigger with decreasing particle size or increasing water content, but it was a little affected with increasing bed temperature and pressure. The bed temperature was varied in the range of 1$0^{\circ}C$ (equation omitted) T (equation omitted) 5$0^{\circ}C$ and the pressure in the range of 10 kPa (equation omitted) P (equation omitted) 190 kPa. The results show that 0.10～0.18 W/mㆍK of effective thermal conductivity measured for the zero water content.

• KIEAE Journal
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• v.13 no.2
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• pp.107-112
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• 2013

The purpose of this study is to analyze an insulation property and to establish a design standard for the underground space in architecture. Insulation materials for this study are 12 kinds of Insulation which qualified KS standards(3 classes of EPS type 1, 3 classes of EPS type 2(Neopor), 3 classes of XPS and 3 classes of PU Boards). For insulation materials of underground space, insulating and water tightening property are desired. So conductivity for insulating and water absorption for water tightening are measured in this study. Temperature, insulation is exposed to in the underground space, is different from temperature above the ground. Conductivity is measured in a temperature of $17^{\circ}C$, $20^{\circ}C$, $23^{\circ}C$ and $26^{\circ}C$. In KS standards, water absorption are measure after 24 hours, but insulation is exposed to water for a long time in the underground. So after 110 days, water absorption are measured. As time goes by, increasing of water absorption means decreasing of water tightening and insulating. So after water absorption had measured for 110 days, conductivity has measured again. As a result, XPS is selected as optimized insulation for underground. And Conductivity of XPS insulation with water should be added by 20%.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.4
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• pp.1-11
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• 2013

Unsaturated hydraulic conductivity function is one of key parameters to solve the flow phenomena in problems of landslide. Prediction models for hydraulic conductivity function related to soil-water retention curve equations in many geotechnical applications have been still used instead of direct measurement of the hydraulic conductivity function since prediction models from soil-water retention curve equations are attractive for their fast and easy use and low cost. However, many researchers found that prediction models for the hydraulic conductivity function can not predict the hydraulic conductivity exactly in comparison with experimental outputs. This research introduced an inverse analysis to evaluate the hydraulic conductivity function corresponding to experimental output from the flow pump system. Optimisation process was carried out to obtain the hydraulic conductivity function. This research showed that the inverse analysis with flow pump system was suitable to assess the hydraulic conductivity in unsaturated soil, and the prediction models for the hydraulic conductivity were led to the significant discrepancy from actual experimental outputs.

• Journal of ILASS-Korea
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• v.21 no.2
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• pp.111-115
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• 2016

This paper experimentally reports the effect of suspension stability on the thermal conductivity of water-based Au nanofluids. For this purpose, the water-based Au nanofluids are prepared by the one-step method called electro-chemical method with volume fraction of 0.0005%. The thermal conductivity of water-based Au nanofluids is measured from $22^{\circ}C$ to $42^{\circ}C$ using the transient hot wire method. To quantify the suspension stability of Au nanofluids, the suspension stability of nanofluids is evaluated using the in-house developed laser scattering system at a fixed wavelength of 632.8nm with the elapsed time. Based on the experimental results, the both thermal conductivity and suspension stability of water-based Au nanofluids are gradually decreased according to the time. These results experimentally show that the suspension stability of water-based Au nanofluids is the one of the important factor of thermal conductivity.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.427-434
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• 2000

Hydraulic conductivity of soil-cement was measured as a function of some selected construction variables that are often encountered in practice. They are initial (or compaction) water content, delayed compaction after mixing, and repeated freezing and thawing. Sandy and clayey soils were used. The hardening agent used was a cement based soil stabilizer consisting of 80% of ordinary Portland cement and 20% of a combination of supplementary materials. Hydraulic conductivity of soil-cement with varying initial water content was, in trend, similar to that of compacted clay. Hydraulic conductivity of soil-cement decreased with increasing initial water content and reached its minimum when compacted wet of optimum water content. Pore size distributions of soil cement at different initial water contents were analyzed using mercury intrusion porosimetry. The analysis showed that dryer condition led to the formation of larger pores with lesser total pore volume; smaller pores with larger total pore volume at wetter condition. Hydraulic conductivity of soil-cement increased by orders in magnitude when specimen underwent delayed compaction of longer than 4 hours after mixing and repeated freezing and thawing.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.5 no.2
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• pp.17-24
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• 2002

This research was conducted to investigate the influences caused by solifluction soil on the physicochemistry of stream water quality at the riparian area four points in the northeastern part of the Bughansan National Park from March to May of 2001. The average pH of stream water was higher than those in the caused by solifluction soil. The average electrical conductivity of upstream water was about 0.8~1.7 times lower than those in the caused by solifluction soil, but the average electrical conductivity of downstream water was about 1.6~3.8 times higher than those in the caused by solifluction soil. Therefore, these results showed that the water quality of downstream was worse than that of upstream. Twelve factors including the physicochemistry on the stream water and caused by solifluction soil were analyzed by spss/pc+ for the data collected from during March to May of 2001. pH of stream water was very significantly correlated with pH and electrical conductivity at the caused by solifluction soil. And the electrical conductivity of stream water was very significantly correlated with electrical conductivity and the amount of cation($Na^+$, ${NH_4}^+$, $Mg^{2+}$) at the caused by solifluction soil.

• Journal of the Korean Geotechnical Society
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• v.20 no.3
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• pp.47-51
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• 2004

An unsaturated hydraulic conductivity function and a soil-water characteristic curve are the essential constitutive factors in studying unsaturated soils. In order to obtain the unsaturated hydraulic conductivity function, prediction functions, which are based on the soil-water characteristic curve, have been used because it is difficult to measure the unsaturated hydraulic conductivity function directly. In this study, a parameter estimation method using the flow pump technique is introduced to determine the unsaturated hydraulic conductivity function. This method provides more accurate and independent solution than previous methods for the determination of the unsaturated hydraulic conductivity function which is not subordinate to the soil-water characteristic curve or prediction models.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3142-3147
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• 2008

A simple transient simulation of ground source heat pump system was carried out to investigate the effects of ground thermal conductivity on its performance. The TRNSYS code with a simple water to water heat pump model was used to compare the COP variation of the system. A new ground heat exchanger called by semi-closed loop was proposed and constructed in the real site. The effective thermal conductivity was measured using the test equipment developed by according to the line source model. The simulation results showed that highly efficient thermal conductivity of the grout material could increase the performance of the heat pump system very well. And the new ground heat exchanger showed the increased effective thermal conductivity as the penetration water flow rate(PWFR) was increased. Therefore, the performance improvement of the heat pump system using the proposed ground heat exchanger can be expected.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3371-3376
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• 2007

The design of a ground-source heat pump system includes specifications for a ground loop heat exchanger where the heat transfer rate depends on the thermal conductivity of the ground. To evaluate this heat transfer property, in-situ thermal response tests on four vertical test boreholes with different grouting materials were conducted by adding a monitored amount of heat to water over various test lengths. By measuring the water temperatures entering and exiting the loop, water flow rate, and heat load, effective thermal conductivity values of the ground were determined. The effect of increasing thermal conductivity of grouting materials from 0.82 to 1.05 W/m$^{\circ}C$ resulted in overall increases in effective ground thermal conductivity by 25.8% to 69.5%.