• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.73-76
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• 2009

Generally, wind or solar power system is operated as a stand-alone power system, the efficiency of which could be higher by designing wind-solar combined system considering average wind speed and solar radiation of the desert region, Mongolia. This system is designed to generate electricity for power users and pumps the ground water for irrigation using deep well pump. The ground water can be used for farming or forestation where there is no or little irrigation system. In connection with this study, a renewable energy park, Green Eco Energy Park, was developed at about 50km east of Ulaanbaatar. 3 sets of 10kW wind power generator and 70 kW of solar power module were installed there. The electricity generated from the system is used to on-site office building and deep well pump for ground water pumping. A 10kW stand-alone solar pumping system, which has no rechargeable battery system, is installed to pump the ground water with the amount of generated power. The ground water is stored in 3 artificial ponds and then it is used for raising nursery tree and farming. The purpose of this study is to provide a possible energy solution to desert regions where there is no or little power system. The system also supply power to ground water pump, and the water can be used for farming and forestation, which will also be a solution of preventing desertification or spreading of desert area.

• Membrane Journal
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• v.23 no.2
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• pp.119-128
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• 2013

In this research, PEI/PEBAX composite hollow fiber membrane was used for the removal of water vapor from gases. PEI (Polyetherimide) substrate membrane was spinned by dry-wet phase inversion method and coated with PEBAX (Polyether block amides) 3533 and PEBAX1657. Fabricated fibers typically had an asymmetric structure of a dense top layer supported by a sponge-like substructure through scanning electron microscopy (SEM). $H_2O/N_2$ mixture gas was used to compare the performance of separation according to temperature, pressure and water activity. The results of PEBAX3533 and PEBAX1657 composite membranes respectively showed $H_2O/N_2$ selectivity of 61.7~118.5 and 85.3~175.4 according to operating conditions. PEBAX3533 composite hollow fiber membranes module showed the water vapor removal of 90%.

• Journal of the Korean Solar Energy Society
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• v.26 no.3
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• pp.79-87
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• 2006

This study aims to presents the applicability of apartment building for renewable energy systems using method of uncomplicated calculation and computer simulation. According to the weather conditions (NASA Surface meteorology and Solar Energy) analysis, it has been found that photovoltaic and wind power system can be applied to apartment buildings application. In case study considering layout and block plan, adaptation of solar water heating, photovoltaic and wind energy system to apartment buildings was proved to produce a profit. And the application strategies of renewable energy systems can be used not only for the investment decisions for economic analysis but also for the comparative analysis of uncomplicated calculation and computer simulation.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.591-594
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• 2005

Geothermal energy becomes to be one of the promising energy sources. In this study, technology using water thermal energy from riverbank filtration system(including alluvial and riverbed deposit) is reviewed and checked as an energy resources. The objects of this study are (1) long-term monitoring of alluvial and riverbed sites, (2) preliminary design of cooling and heating system at riverbank filtration facility, and (3) calculation of potential groundwater heat energy, including riverbank filtration system. Measuring data of alluvial and riverbank filtration show slight fluctuations comparing to temperature of atmospheric air which indicates that groundwater obtained from the riverbank filtration system have a sufficient potential as a source of cooling and heating energy.

• Advances in concrete construction
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• v.13 no.6
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• pp.423-431
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• 2022

Although the influence of moisture content on the mechanical properties of concrete has been studied for a long time, research related to its influence on the damping and energy dissipation property of concrete structure is still very limited. In this paper, the relationship between damping property and moisture content of concrete using cyclic uniaxial compression is firstly presented, and the mechanism of the influence of moisture content on concrete damping and energy dissipation capacity is analyzed. Based on the experimental research, moisture-related damping and energy dissipation model is proposed. Results show that the dissipated energy of concrete and loss factor increase as the moisture content increasing. The energy dissipation coefficient reflecting the influence of stress level of concrete under cyclic load, decreases first and then increases as the moisture content increasing. The mechanism of moisture-related energy dissipation behavior can be divided into the reactive force of water, the development of the internal micro cracks and the pore water pressure. Finally, the proposed moisture-related damping and energy dissipation model are verified.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.2
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• pp.103-110
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• 2005

Proton conducting solid polymer electrolyte (SPE) membranes have been used in many energy technological applications such as water electolysis, fuel cells, redox-flow battery, and other electrochemical devices. The availability of stable membranes with good electrochemical characteristics as proton conductivity at high temperatures above 80 $^{\circ}C$ and low cost are very important for its applications. However, the presently available perfluorinated ionomers are not applicable because of high manufacturing cost and high temperature use to the decrease in the proton conductivity and mechanical strength. In order to make up for the weak points, the block copolymer (BPSf) of polysulfone and poly (phenylene sulfide sulfone) were synthesized and sulfonated. The electrolyte membranes were prepared with phosphotungstic acid (HPA)/sulfonated BPSf via solution blending. This study would be desirable to investigate the interaction between the HPA and sulfonated polysulfone. The results showed that the characteristics of SPSf/HPA blend membrane was a better than Nafion at high temperature, 100 $^{\circ}C$. These membranes proved to have a high proton conductivity, $6.29{\times}10-2$ S/cm, a water content, 23.9%, and a ion exchange capacity, 1.97 meq./g dry membrane. Moreover, some of the membranes kept their high thermal and mechanical stability.

• Membrane and Water Treatment
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• v.14 no.2
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• pp.85-93
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• 2023

Membrane separation is widely used for several applications such as water treatment, membrane reactors and climate change. Cross-linked organic-inorganic hybrid polyvinylidene fluoride (PVDF) / Tetraethyl orthosilicate (TEOS) was adopted for the preparation of optimized hollow membrane (HFM) for membrane distillation or other low pressure separators for mechanical properties and permeability under varying pretreatment schemes. HFMs were prepared on semi-pilot membrane fabrication system. Novel adopted post-treatment schemes involved soaking in glycerol, magnesium sulphate (MgSO₄), sodium hypochlorite (NaOCl), and isopropanol for different durations. All fibers were characterized for morphology using a scanning electron microscope (SEM), surface roughness using atomic force microscope (AFM), elemental composition by examining Energy Dispersive Spectroscopy (EDS), water contact angle (CA°) and porosity. The performance of the fibers was evaluated for pure water permeation flux (PWF). Post-treatment with MgSO₄ gave the highest both tensile modulus and flux. Assessment of properties and performance revealed comparable results with other organic-inorganic separators, HF or flat. In spite of few reported data on post treatment using MgSO₄ in presence of TEOS, this proves the potential of low cost treatment without negative impact on other membrane properties. The flux is also comparable with hypochlorite which manifests substantial precaution requirements in actual industrial use.The relatively high values of flux/bar for sample treated with TEOS, post treated with MgSO₄ and hypochlorite are 88 and 82 LMH/bar respectively.

• Journal of the Korean Society of Radiology
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• v.16 no.1
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• pp.61-66
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• 2022

The purpose of this study is to derive photon energy fluence and mass energy absorption coefficient for 1 Gy of absorbed dose of water in brachytherapy using an Ir¹⁹² source. From the radiotherapy physics written by Khan, the half-value of lead for the gamma ray beam of the Ir¹⁹² source was obtained. The linear attenuation coefficient and the mass attenuation coefficient were calculated from the obtained half-value layer of lead. By matching the calculated lead mass attenuation coefficient with the NIST mass attenuation coefficient data, the photon energy of the matching mass attenuation coefficient was determined as the effective energy. By matching the determined effective energy with the photon energy of the NIST data on the mass energy absorption coefficient of water, the mass energy absorption coefficient of water was obtained as 0.03273 cm²/g(32.73 cm²/kg). The photon energy fluence was calculated as 0.03055 J/cm² by dividing the obtained mass energy absorption coefficient (32.73 cm²/kg) by the absorbed dose of water 1 Gy.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.663-665
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• 2003

A field spectroradiometer SE-590 was used to measure the spectral reflectance of water body. The reflectance was calculated as the ratio of surface water radiance to the standard whiteboard radiance nearly measured at the same time. Water samples were taken simultaneously for determining their chlorophyll-a, suspended solid (SS) and transparency. The relationships between those water quality parameters and spectral reflectance were analy zed using stepwise multiple regression to derive optimal prediction models . The multiple regression was also applied to the SE-590 simulated SPOT bands. The SPOT image of the same day was also analyzed using the same method to compare the statistical results. It showed that the multiple regression models using the SE-590 reflectance data got the best water quality prediction results. The evaluated RMS error of chlorophyll-a, SS and transparency of water quality parameters were 0.57 ug/l, 0.2 mg/l and 0.17 m, respectively, and the RMS errors were 0.36 ug/l, 0.49 mg/l and 0.42 m for SPOT data, respectively. The SE-590 simulated SPOT three bands data obtained the worst results and the RMS errors were 1.77 ug/l, 0.49 mg/l and 0.37 m, respectively.

• Journal of the Korean Solar Energy Society
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• v.25 no.2
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• pp.63-69
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• 2005

This study is the survey of a transition procedure of building services systems(heat source, HVAC, water supply) through the survey of existing office buildings, building design documents. The preference & major consideration of system selection is the engineer's opinions. The results of this survey can be used in selection of building services system design. In this survey, "Hot & cold water generator system" and "single duct CAV+FCU system", "Elevated water tank system" are selected. The most important consideration in system selection is the energy saving in heat source system, and comfort in HVAC system, and water pressure in water supply system. They prefer "steam boiler+absorption chiller system" for heat source system, "steam boiler+ice thermal storage system", "hot & cold water generator system", "district heating+absorption chiller system" : "single duct CAV+FCU system" and "single duct VAV+convector system" for HVAC system: and "booster pump system" for water supply system.