• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.250-255
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• 2009

This study was analyzed the long term performance of the demonstration system for solar energy desalination in Jeju. we used a solar thermal system as heat source of the single-stage fresh water generator with plate-type heat exchangers and a photovoltaic power system as electric source for hydraulic pumps. The demonstration system was designed and installed at Jeju-island in 2006. The system was comprised of the desalination unit with daily fresh water capacity designed as $2m^3$ a $120m^2$ evacuated tubular solar collector to supply the heat, a $6m^3$ heat storage tank, and a 5kW photovoltaic power generation to supply the electricity of hydraulic pumps for the heat medium fluids. Through the operation during about 3 years, In a clear day more than $400W/m^2$, the daily fresh water showed to produce more than about 500liter, and from January, 2007 to March, 2009 for 3 years, solar irradiance daily averaged was measured $370W/m^2$, the daily fresh water yield showed that can be produced about 330liter.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.180-183
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• 2009

In this study, Urban Climate Simulation was performed by 3-Dimensional Urban Canopy Model. The characteristics of urban climate was analyzed combining artificial land coverage, building size, heat production from the air conditioning and topographic conditions as physical variables which affects urban climate characteristics. The results are as follows. (1)The aspects of the urban climatal change is derived to be related to the combination of the building coverage ratio, building height and shading area. (2)Whole heat generation was influenced by the convective sensible heat at the lower building height and by the artificial heat generation at the higher one over 20-story building influence to some extent of the building coverage ratio. The effect of the altitude is not more considerable than the other variables as below $1^{\circ}C$ of the air temperature.

• Journal of the Korean Solar Energy Society
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• v.39 no.6
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• pp.67-82
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• 2019

This study aims to examine the impacts of built environmental features on the nocturnal and diurnal temperatures during the heat wave season in Gwangju, Korea. Built environmental measures are summarized at micro-scale level, such as 50 meters and 100 meters from temperature monitoring spots. Regressing the built environment on nocturnal and diurnal temperatures, we estimate how the artificial constructs contribute to temperature either day and night times. We found that impervious surface ratio is positively and negatively associated with nocturnal and diurnal temperatures, respectively. Buildings and structures tend to construct high thermal mass and absorb heat during day time and emit it for the night time. This property contributes to the nocturnal temperature model. On the other hand, urban areas with more vertical structure tend to block sun radiation more than rural, and it is more likely to find the negative relationship between impervious surface ratio and the diurnal temperatures.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.1
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• pp.115-126
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• 1998

A GDHS(Geothermal District Heating System) is a heating system supplying a group of districts with heat extracted from geothermal sources. Due to various advantages of GDHS including the saving of fuel consumption as well as the reduction of air pollution, a world-wide trend is to replace central/individual heating systems with GDH systems. The basic point of this paper is that a crash program mentality leads to inappropriate decisions about policy issues in large-scale research and development like the development of GDHS, R&D funding should be viewed as a sequential decision, not a once-and-for-all choice. Hence we develop on economic feasibility assessment model based on a continuous sequential decision process for the Chejoo Island GDHS Project by modifying Roberts's model.

• Journal of the Korea Safety Management & Science
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• v.21 no.4
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• pp.45-49
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• 2019

The basalt fiber is expected to become a trend for industrial fibers as they have better properties of heat-resistant, non-combustion, absorbent, soundproof, moistureproof, lightweight, corrosion resistant, and high strength properties. Also, the fiber is found to be non-toxic and harmless to the human body. Therefore, in this study, we analyzed the chemical and mineral compositions of powdered sludge of basalt produced at seven sites on Jeju Island for the development of fire resistance insulating material for a building. The results showed that the basalt stone sludge is made from only sodium calcium aluminum silicate and ferridioside components unlike the basalt rock.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.3
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• pp.1-6
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• 2019

The basalt fiber, which is found to be non-toxic and harmless to the human body, is expected to become a trend for industrial fibers as they have better properties of non-combustion, heat-resistant, soundproof, absorbent, moistureproof, wear-resistant, corrosion resistant, lightweight, and high strength properties. Thus, in this study, we analyzed the chemical compositions of basalt produced at seven sites on Jeju Island for making a high value inorganic insulation material. The results showed that the MgO content of basalt collected from the eastern part of Jeju Island was higher than 7.5 percent, while that of the western region was less than 6 percent.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.1
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• pp.1-9
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• 2000

Vertical temperature distributions in muddy intertidal sediments near the Jebu Island on the west coast of Korea were obtained during the period of ebb tide which occurred in day time. The observations of mud temperature were made with thermistor embedded probe at 2cm interval for 18cm-layer of sediment for five different months of the year. Temporal changes in the vertical profile of the sediment temperature are strongly depend on the air temperature, the previous time of flood tide and the time of ebb tide. Heat exchanges in the surface layer (0-2 cm) in terms of magnitude and direction are greater than and opposite to those in the deeper sediment layer (8-12 cm), respectively and do not show any significant seasonal variations. In general, the surface layer gains heat while the deeper layer loses the heat. By using the 1-D diffusion equation temporal vertical profiles of the sediment temperature were obtained and were compared with the observed ones. The results show that in the sediment layer below 4 cm-depth the heat transport is predominantly by molecular diffusion. The average magnitude of heat flux into the sediment layer (0-18 cm) during the ebb tide when the mudflats were exposed in the middle of the day were between 4.1 and $28.9\;W/m^2$.

• Journal of Korea Planning Association
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• v.53 no.7
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• pp.109-126
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• 2018

The purpose of this study is to identify the spatial types for thermal environment improvement considering heat flux and its spatial context through empirical orthodox formulas. First, k-means clustering was used to classify values of three kinds of heat flux - latent, sensible and storage heat. Next, from the k-means clustering, we defined a type of thermal environment (type LHL) where improvement is needed for more comfortable and pleasant thermal environment in the city, among the eight types. Lastly, we compared and analyzed the characteristics of each classified thermal environmental types based on land cover types. From the study, we found that the ratio of impervious surfaces, roads, and buildings of the type LHL is higher than those of the type HLH (relatively thermal comfort environment). In order to improve the thermal environment, the following contents are proposed to urban planners and designers depending on the results of the study. a) Increase the green zone rate by 10% to reduce sensible heat; b) Reduce the percentage of impermeable surfaces and roads by 10% ; c) Latent heat increases when water and green spaces are expanded. This study will help to establish a minimum criterion for a land cover rate for the improvement of the urban thermal environment and a standard index for the thermal environmental improvement can be derived.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.6
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• pp.1-13
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• 2018

Mapping radiation heat flux of urban area is essential for urban design and landscape planning. Because controlling urban geometry and generating green space are important urban design strategies for reducing urban heat, urban planner and designer need to recognize the micro urban heat distribution for adequate urban planning. This study suggests a new methodology for mapping urban radiation heat flux in a micro scale considering buildings and trees' shade. For doing that, firstly, we calculate net radiation for each urban surfaces (building, road (not shaded, building shaded, tree shaded), ground (not shaded, building shaded, tree shaded), tree (not shaded, building shaded)). Then, by multiplying the area ratio of surfaces to the net radiation, we can obtain the radiation heat flux in micro-scale. The estimated net radiation results were found to be robust with a $R^2$ of 90%, which indicates a strong explanatory power of the model. The radiation heat flux map for 12h $17^{th}$ August explains that areas under the building and tree have lower net radiation heat flux, indicating that shading is a good strategy for reducing incident radiation. This method can be used for developing thermal friendly urban plan.

• Tunnel and Underground Space
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• v.26 no.4
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• pp.266-273
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• 2016

We have numerically modeled thermal evolution of Ulleung Island after an emplacement of magma chamber. The disk-shape magma chamber is assumed to locate at 2.9 km beneath the island and has a diameter and a thickness of 10 km and 300 (or 600) m, respectively. The geothermal gradients evaluated from the numerical modeling coincide well with the range of the geotherms (${\sim}95^{\circ}C/km$) observed from the well logging. Although there are limitations in the application of the numerical results directly to the interpretation of the observed geotherms, we believe that an existence of a hot magma chamber in molten or in solidified state is the most plausible explanation for the observed geotherms.