• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.158-159
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• 2005

This study showed that the highest temperature point of the Dongrae thermal spring in Pusan was moved to the north direction of the Dongrae fault as times goes by. The Br concentration(1.5mg/L) in Dongrae thermal waters indicated the influence of 2% seawater mixing. If the simple mixing without hydrochemical reaction occurs between seawater and thermal water, the concentration of Mg will be about 20mg/L. But the low concentration(0.1 mg/L) of Mg, contrary to high concentration(10 mg/L) of surrounding groundwater not affected by thermal water, suggested the thermal water, seawater and rock interactions. The calculation of saturation index(SI) by using the geochemical code of EQ3NR showed that the Mg in thermal groundwater, which was introduced by seawater, was removed by the precipitation of Antigorite (SI: log Q/K =71.753, $Mg_{48}Si_{24}O_{85}(OH)_{62}$) and Tremolite (SI: 8.463, $Ca_2Mg_5Si_8O_{22}(OH)_2$), Talc (SI: 6.409, $Mg_3Si_4O_{10}(OH)_2$), Dolomite (SI: 2.014, $CaMg(CO_3)_2$), Chrysotile (SI: 3.698, $Mg_3Si_2O_5(OH)_4$) in the crack of fault zone. The highest temperature point in the study area will move to north direction and stop in the Jangjun area without the input of seawater.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.4
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• pp.109-120
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• 2016

This study aims to assess vulnerability in urban thermal environments of Seoul by using indicators frequently used in previous studies as well as effective indicators for spatial planning like urban and environmental planning. For this purpose, fifteen indicators that influence urban thermal environments such as heat waves, urban heat island effects, and urban micro-climates were identified based on literature reviews. Indicators for presenting urban structure and spatial properties were included; for example, building volume as 'exposure to climate', buildings completed before 1980 as 'sensitivity', and green space areas as 'adaptive capacity'. Among them, twelve indicators were applied to assess vulnerability in urban thermal environments of Seoul by using a GIS spatial analysis combined with fuzzy logic. The results show that the Gangnam area is identified as more vulnerable to a heat environment as compared to the Gangbuk area. In the Gangnam area, Seocho-gu, Gangnam-gu, Dongjak-gu, Yeongdeungpo-gu, Gangseo-gu were relatively high in vulnerability, while Dongdaemun-gu, Gangbuk-gu, Gwangjin-gu, Jungrang-gu were relatively high in the Gangbuk area. Gwanak-gu, Dobong-gu, Eunpyeong-gu, and Nowon-gu, which include forested areas, have low vulnerability in the sectors of 'exposure to climate' and 'sensitivity' due to the impact of Gwanaksan and Bukhansan. However, some areas with high vulnerability like Seocho-gu and Gangnam-gu may have lower vulnerability if the indicator 'status of air conditioning' from the sector of 'adaptive capacity' is used. This study could support the establishment of a practicable thermal environment policy and spatial planning to reduce heat-related risks in the field of urban and environmental planning.

• Journal of Surface Science and Engineering
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• v.55 no.6
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• pp.368-375
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• 2022

YSZ (Yttria Stabilized Zirconia) is used as a thermal barrier coating material for gas turbines due to its low thermal conductivity and high fracture toughness. However, the operating temperature of the gas turbine is rising according to the market demand, and the problem that the coating layer of YSZ is peeled off due to the volume change due to the phase transformation at a high temperature of 1400℃ or higher is emerging. To solve this problem, various studies have been carried out to have phase stability, low thermal conductivity, and high fracture toughness in a high temperature environment of 1400℃ or higher by doping trivalent and tetravalent oxides to YSZ. In this study, the monoclinic phase formation behavior and crystallinity were comparatively analyzed according to the total doping amount of oxides by controlling the doping amounts of Sc₂O₃ and Gd₂O₃, which are trivalent oxides, and TiO₂, which are tetravalent oxides, in YSZ. Through comparative analysis of monoclinic phase formation and crystallinity, the thermal conductivity of the thermal barrier coating layer according to the amount of doping was predicted.

• 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.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.1-6
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• 2014

In-wheel driving inverter inside engine room sometimes operates in the harsh environment like high temperature of about $105^{\circ}C$. Especially, the size and power density of the inverter has become smaller and more increased. Thus, it is essential to manage the temperature of the inverter with IGBT (Insulated Gate Bipolar Transistor) switching devices for performance and endurance, because the temperature can be getting increase. In this paper, we performed the thermal flow analysis of inverter models with wave type and pin fin type cooling channels, and investigated the heat transfer characteristics of the inverter models using cooling water on channels at 8 L/min and $65^{\circ}C$. Also, we compared the thermal performance under various conditions such as coolant flow rate and layered power module structure. Therefore, we determined the feasibility of the initial inverter models and the thermal performance enhancement.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.928-933
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• 2003

For simulation of three-dimensional turbulent flow with LES and DNS takes much time and expense with current available computing resources. It is nearly impossible to simulate turbulent flow with high Reynolds number. So, the emerging alternative is the Grid computing for needed computation power and working environment. In this study, the CFD code was parallelized to adapt it for the parallel computing under the Grid environment. In the first place, the Grid environment was built to connect the PC-Cluster facilities belong to the different institutions using communication network system. And CFD applications were calculated to check the performance of the parallel code developed for the Grid environment. Although it is a fundamental study, it brings about a important meaning as first step in research of the Grid.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.7
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• pp.635-640
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• 2015

In this paper, we report a non-explosive separation device for a small satellite which utilize a shape memory alloy actuator. Based on previous research, we try to increase the reliability of the proposed device by changing some components. It enables the proposed device to activate under high preload. Also, we confirm it generates low shock which is main advantage of non-explosive separation device. Finally, vibration test which mimics launching environment and thermal vacuum test which mimics space environment are carried out respectively. After each environment test, we confirm the proposed device is successfully activated. Conclusively, we develop a non-explosive separation device which can activate with low shock under high preload after shock and environment tests(vibration and thermal vacuum tests).

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.2
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• pp.1-23
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• 2018

This study aims to propose a way for evaluating thermal environment vulnerability associated with policy to improve thermal environment. For this purpose, a variety of indices concerning thermal vulnerability assessment and adaptation policies for climate change applied to 17 Korean cities were reviewed and examined. Finally, 15 indices associated with policies for improving thermal environment were selected. The selected indices for thermal vulnerability assessment were applied to Daegu Metropolitan City of South Korea as a case study. As results, 15 vulnerability maps based on the standardized indices were established, and a comprehensive map with four grades of thermal vulnerability were established for Daegu Metropolitan City. As results, the area with the highest rated area in the first-grade(most vulnerable to heat) was Dong-gu, followed by Dalseo-gu and Buk-gu, and the highest area ratio of the first-grade regions was Ansim-1-dong in Dong-gu. Based on the standardized indices, the causes of the thermal environment vulnerability of Ansim-1-dong were accounted for the number of basic livelihood security recipients, the number of cardiovascular disease deaths, heat index, and Earth's surface temperature. To improve the thermal environment vulnerability of Ansim-1-dong, active policy implementation is required in expansion and maintenance of heat wave shelters, establishment of database for the population with diseases susceptible to high temperature environments, expansion of shade areas and so on. This study shows the applicability of the vulnerability assessment method linked with the policies and is expected to contribute to the strategic and effective establishment of thermal environment policies in urban master district plans.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.99.1-99.1
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• 2016

The materials for an electronic packaging provide diverse important functions including electrical contact to transfer signals from devices, isolation to protect from the environment and a path for heat conduction away from the devices. The packaging materials composed of metals, ceramics, polymers or combinations are crucial to the device operating properly and reliably. The demand of effective charge and heat transfer continuous to be challenge for the high-speed and high-power devices. Nanomaterials including graphene, carbon nanotube and boron nitride, have been designed for the purpose of exploiting the high thermal, electrical and mechanical properties by combining in the matrix of metal or polymer. In addition, considering the inherent electrical and surface properties of graphene, it is expected that graphene would be a good candidate for the surface layer of a template in the electroforming process. In this talk, I will present recent our on-going works in nanomaterials for microelectronic packaging: 1) porous graphene/Cu for heat dissipations, 2) carbon-metal composites for interconnects and 3) nanomaterials-epoxy composites as a thermal interface materials for electronic packaging.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.408-411
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• 2005

Solar fuel production technology using high-temperature solar furnace was briefly reviewed in this paper. 'Hydrogen' which is known to be the most promising energy carrier in the near future is to be generated environment-friendly from non-carbon resources. Combination of solar furnace operated by concentrated solar energy and high-temperature thermal reactions could be one of the most efficient ways to fulfill this need eventually. Various reaction mechanisms are feasible within a wide spectrum of solar fuel production technology, but intensive research efforts in related key areas need to be taken for successful development and commercialization of the technology.