• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.4
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• pp.475-482
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• 1998

In this paper, an experimental study was conducted to investigate the performance of the spherical ice particle production system which uses the technology of water spray in a vacuum chamber for increasing the heat transfer area. As a result, following conclusions were obtained. The diffusion-controlled evaporation model agreed relatively well with experiments. The spray flow rate influences the performance of the system rather than any other factors, for example, the spray nozzle position, the nozzle number. As the spray rate increases, the system efficiency increases. It is due to the entrainment of small droplets among the spray with the exhausted vapor. Thus the system should be designed and operated to prevent the entrainment. Assuming the compressor efficiency to be 70%, the COP of the system reaches highly up to 6 at a maximum spray rate. Under the conditions, however, the rigid ice layer is obtained because ice particles bond together with increase of the spray rate. Therefore, the spray rate should be controlled properly to make the spherical ice particles.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.535-539
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• 2001

The aim of this paper presents to develop a computer-aided design system for water gate on AutoCAD R2000system. The developed system has been written in AutoCAD and Visua ILISP with a personal computer, and is composed four modules which are the gate-lifter input module, guide-frame input module, template input module and upgrade module. Based on knowledge-based rules, the system is designed by considering several factors, such as width and height of a water gate, material, object of product and maximum depth of water. Employing the developed system enable the designer and manufactures of water gate to be more efficient in this field, and its potential capability for enhancement included FEM(Finite Element Method) and quotation system.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.04a
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• pp.55-62
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• 1997

In Japan, the membrane filtration is becoming a common technology for municipal water supply system especially for small plant. 6 years before (1991), the national research project of membrane filtration for small plant has started. The project was named as "MAC 21", MEMBRANE AQUA CENTURY 21. In the project the Ministry of Health and Welfare, 8 universities and 18 water treatment plant companies have been involved. This was the first attempt to research a common theme in joint with government, universities and private companies. After three years, the guide line for membrane filtration application for small plant has been established. This has promoted to install some actual plant. And also, another joint research for "RESEARCH OF MEMBRANE FILTRATION FOR ADVANCED WATER TREATMENT" has started in 1994 and completed in March, 1997. The project was named as MAC21. In the former project the main objectives were removal of turbidity and bacteria from water. However, in new project the objective was establishment of the further advanced membrane filtration technology which would be applicable for trace chemical components removal such as tri-halo-methane pre-courser, agricultural chemicals removal, offensive smell and taste removal and virus removal. For the objectives, application of nanofiltration and hybrid-system, a combination of micro-filtration ultra-filtration with biological, ozone and activated carbon treatment process have been studied. In addition, application of membrane filtration for treatment of back-wash waste water originated from membrane filters and conventional sand filters has.been studied. At the end of March of this year, about 30 membrane filtration plants are actually supplying the water, the total treatment capacity is about 6,000 m$^{3}$/day and another 20 will be installed within one year.led within one year.

• Journal of Power System Engineering
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• v.4 no.3
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• pp.34-39
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• 2000

Performance data in the literature on air lift pumps have been based primarily on pumps of long length and large diameter (high lift pumps). Since mariculture operations involve pumps of relatively short length and small diameter, performance data are required for efficient operation. To provide such data, an experimental apparatus was designed and fabricated to test all lift pumps from 2.1 to 3.4 cm inside diameter and from 40 to 300 cm in length. Instrumentation was provided to measure water flow rate and air flow rate as well as water temperature, air temperature, and pressure throughout the system. Results from this study correlate well with high lift pump data in that, for a given pump geometry, maximum water flow occurs for a specific air flow rate. Driving the pump with air flows larger or smaller than this optimum flow rate will decrease the pumping rate. The optimum flows are significantly different for low lift pumps compared to high lift pumps. However, the pumping rate for low lift pumps approaches that for high lift pumps with increasing length.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.6
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• pp.659-666
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• 2015

In this study, Hazen-Williams C value of pipes in wide waterworks system was estimated and statistically analyzed. Hazen-Williams C value of water pipe was predicted after 20 years of service period. From the results, it was found that C value of water pipe for treated water maintained higher value of 110 after 20 years of installation. Furthermore, it was found that velocity coefficients of steel pipe for less than and more than 20 years of installation were 117.7 and 109.3, respectively. C value of ductile iron pipe for less than and more than 20 years of installation were 118.1 and 114.2, respectively. In this study, it was also found that small value of C is used in the design of water pipe system. Therefore, excessively bigger size of pipe can be determined in the design of water pipe system. From the results of present study, optimum value of C can be used to avoid the oversized design of water pipe system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.156-161
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• 2004

The application of solar energy, in the field of alternative energy, was on the increase tendency. In the case of advanced nations, through continuous R&D, solar hot water heater with high efficiency has been used for the house and the industrial process on business, advanced nations were reached up the experimental stage of solar generation system. But, the actual circumstance of the domestic has been not accomplished the popularization of solar hot water heater and the settlement of it which is the fundamental stage of the solar energy usage. This trouble, the domestic was flooded with small enterprise for producing solar hot water heater, was caused by the popularization and the production without verification of performance. To supply the monitoring program for evaluating solar hot water heater, this research was purpose to improve the technical development of the enterprise for producing solar-heat hot-water-boiler and served as an aid for the enlargement and the popularization on solar energy.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.7
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• pp.71-80
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• 2004

A system for estimating daily paddy irrigation water requirements was developed to simulate daily stream flows that reflect various upstream and downstream return flows from river basin. Evapotranspiration in paddy fields was estimated using the modified Penman equation. Daily irrigation water requirements of paddy fields were calculated by multiplying the paddy area and the daily decrease in ponding depth. The system was constructed almost completely using images, grids, etc. in Visual Basic 6.0. The developed model was verified in the Damyang dam, and was used to estimate daily paddy irrigation water requirements at 12 small watersheds in Geum river basin for 20 years, from 1983 to 2002, covering paddy field areas of $3,332\~26,422$ ha. The results on the runoff analysis on the inflow to the Daecheong multi-purpose dam with various return flows were satisfactory. They were reasonable compared to the scenario where return flows were not considered.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.41-46
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• 2011

In the present work, a new freeze protection method has been proposed for a natural circulation system of solar water heater. Though electrothermal wire is popularly used for the purpose, there are freezing troubles by wire cut-off and excessive electric power consumption. In the experimental device, hot water in a storage tank was circulated by a small pump and used to heat the outdoor pipes if the cold water pipe surface temperature falls lower than a set point. As a result, It was observed that there was no hot water waste while the solar water heating system operated without freeze and burst.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.435-438
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• 2003

Model for estimating daily paddy water requirements was developed to simulate daily streamflow in upstream and downstream. Evapotranspiration in paddy fields was estimated using modified Penman equation. Daily water requirements in paddy fields were calculated from multiplication of paddy area to ponding depth decreased for one day. And model was constructed with a system form user-friendly and almost completely using controls of image, grid, and etc. in Visual Basic 6.0. The developed model was applied to estimate daily agricultural water requirements at 12 small watersheds during 20 years from 1983 to 2002 with paddy field areas of $3,332{\sim}26,422ha$ in small watersheds, and with agricultural water requirements of $37.22{\sim}294.53mcm$ on yearly average.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.3
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• pp.7-12
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• 2015

Currently water supply system with water storage is generally applied except for small building such as single-family houses, and water supply system on replacing water storage installed system by direct connecting system has been increasing because of sanitary and energy-saving aspects. The purpose of this study is to evaluate energy-saving and environmental efficiency of direct connecting booster pump system in comparison with the water storage installed system. The architectural condition of the evaluation subject is ten-story apartment house in which sixty households live. To calculate the power consumption of the pump, the volume of water supply was determined from existing data and other data, such as head, efficiency of the pump, was the value used for general application in design office. The power consumption of the water supply pump for one day was 8.5 kWh for direct connecting booster pump system, and 22.5 kWh for water storage installed system, and the former system showed energy savings of 62% compared to the latter system. Reduced power consumption also leads to reduction of $CO_2$ emission. According to the criteria presented in the Korea Energy Management Corporation, reducing the 2,410 kg $CO_2$ emission is possible per year.