• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.943-951
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• 1999

The welded structure unnecessarily remains residual stress due to the very high heating of local region and lastly cooling. The residual stress sometimes causes fracture initiation of welded structures. In this paper, distribution and magnitude of tensile and compressive residual stresses in the TIG(Tungsten Inert Gas) welded aluminum alloy such as Al5083-H112 are measured by using the hole-drilling method. Furthermore, the effects of residual stresses in the TIG welded aluminum CCT(Center Crack Tension) and SEN(Single Edge Notched) Specimens on the fatigue crack propagation behavior are analyzed. The fatigue cracks initiated at residual stresses region are influnced by tensile and compressive residual stresses. However, the effects are found to be released fast for both cases according to the cyclic loads and extension of crack length.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.11a
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• pp.43-49
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• 2000

Heat transfer characteristics of self oscillating heat pipe were experimentally investigated for the effect of fill charge ratios and heat loads. The heat pipe used for this study is made of copper capillary, has 0.002m internal diameter, a 0.34m length in one turn and consists of 19 turns. Heating and cooling section each have a length of 70mm. Water was used as working fluid inside heat pipe. As the experimental results, the self oscillating heat pipe was operated by self-exited oscillation and circulation of working fluid and the oscillation within the self oscillating heat pipe assumed chaotic behavior.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.4
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• pp.93-99
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• 2013

Parts and structures such as piston rod and knuckle joint for the use of hydraulic cylinder are often welded together in some fashion, usually due to cost and process effectiveness. Welding strongly affects the material by the process of heating and subsequent cooling as well as by the fusion process with additional filler material. Furthermore, a weld is usually far from being perfect, containing inclusions, pores, cavities, undercuts etc. As a consequence, fatigue failures appear in welded structures mostly at the welds rather than in the base metal, even if the latter contains notches. For this reason, fatigue analyses are of high practical interest for all welded structures under the action of cyclic loads. This paper describes the influence of welding parameters, material combinations and heat treatment on the fatigue behavior of welded cylinder rod. In addition, statistical characterization of stress-life response in weldment of hydraulic cylinder rod are presented.

• Journal of the Korean Solar Energy Society
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• v.29 no.3
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• pp.37-44
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• 2009

The field-surveyed and measured energy consumption data is processed to develop building energy demand models for heating, hot water, cooling, and electricity. The load models are systematically organized as a database and hourly loads for a span of year (8760 hours) are generated by the program. Rased on those models a Microsoft Access application program is developed to calculate energy demands for a Community Energy System (CES) composed of 17 types of buildings. User-friendly interfaces are provided to assist non-expert end users and necessary tools to link the calculation results to subsequent coagulations such as operation simulation or economic assessment.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.127-132
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• 2009

A Microsoft Access application program is developed to calculate energy demands for a Community Energy System (CES) composed of various types of buildings. The field-measured heating, hot water, cooling, and electricity energy consumptions for 14 types of building are systematically organized in forms of database and hourly loads for a span of year (8760 hours) are generated through an automated statistical procedure. User-friendly standard windows interfaces are provided to assist non-expert end users.

• Journal of the Korean housing association
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• v.13 no.4
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• pp.27-33
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• 2002

In Gumi area, the heating and cooling loads for underground building could have not been correctly evaluated since there were no systems accurate underground temperature. For solving this problem two ways of predicting the underground temperature were propose. Firstly, it is to estimate the underground temperature of Gumi area by averaging out the underground temperature of the areas around Gumi city. However, the underground temperature data of the areas around Gumi city was only limited to 0.5m and 1.0m under the ground. Secondly, it is to calculate the underground temperature of Gumi area by using a periodic equation with variable about underground properties. Among these methods, the method of the average date was more correct, but the method of the variable date was more available.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.252-262
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• 2019

Following the earthquake in Gyeongju (2016) and Pohang (2017), South Korea is no longer a safe place for earthquakes. Accordingly, the need for shelters suitable for disaster environments is increasing. In this study, a lightweight composite panel was used to produce post-disaster housing for refugees to compensate for the disadvantages of existing evacuation facilities. For this purpose, an evaluation of structural performance and thermal environment for post-disaster housing for refugees composed of lightweight composite panels was performed. To assess the structural performance, a lateral loading test was conducted on a system made of lightweight composite panels. The specimens consisted of two types, which differed according to the bonding method, as a variable. In addition, the seismic and wind loads were calculated in accordance with KBC 2016 and compared with the experimental results. Regarding the energy performance, optimization of south-facing window planning and window-wall ratio and solar heat gain coefficient were analyzed to minimize heating, cooling, and lighting energy. As a result, the specimens composed of lightweight composite panels will perform sufficiently safely for lateral loads and the optimized window planning will lead to a low-energy operation.

• Journal of the Korean Solar Energy Society
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• v.35 no.2
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• pp.93-101
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• 2015

Zero energy building is a self sufficient building that minimizes energy consumption through passive elements such as insulation, high performance window system and installing of high efficiency HVAC system and uses renewable energy sources. The Korea Government has been strengthening the building energy efficiency standard and code for zero energy building. The building energy performance is determined by the performance of building envelope. Therefore it is important to optimize facade design such as insulation, window properties and shading, that affect the heating and cooling loads. In particular, shading devices are necessary to reduce the cooling load in summer season. Meanwhile, BIPV shading system functions as a renewable energy technology applied in solar control facade system to reduce cooling load and produce electricity simultaneously. Therefore, when installing the BIPV shading system, the length of shadings and angle that affect the electricity production must be considered. This study focused on the facade design applied with BIPV shading system for maximizing energy saving of the selected standard building. The impact of changing insulation on roof and walls, window properties and length of BIPV shading device on energy performance of the building were investigated. In conclusion, energy consumption and electricity production were analyzed based on building energy simulations using energyplus 8.1 building simulation program and jEPlus+EA optimization tool.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.58-68
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• 2009

Low impact development (LID) technique is relatively new concept to reduce surface runoff and pollutant loading from land cover by attempting to match predevelopment condition with various integrated management practices (IMPs). In this study, computational model for designing and evaluating LID, named LIDMOD, was developed based on SCS-CN method and applied at Andong bus terminal to evaluate LID applicapability and design retention/detention area for volume or peak flow control. LIDMOD simulated with 21 years simulation period that yearly surface runoff by post-development without LID was significantly higher than that with LID showing about 2.8 times and LID could reduce efficiently yearly surface runoff with 75% reduction of increased runoff by conventional post development. LIDMOD designed detention area for volume/peak flow control with 20.2% of total area by hybrid design. LID can also efficiently reduce pollutant load from land cover. Pollutant loads from post-development without LID was much higher than those from pre-development with showing 37 times for BOD, 2 times for TN, and 9 times for TP. Pollutant loads from post-development with LID represented about 57% of those without LID. Increasing groundwater recharge reducing cooling and heating fee, creating green refuge at building area can be considered as additional benefits of LID. At the point of reducing runoff and pollutant load, LID might be important technique for Korean TMDL and LIDMOD can be useful tool to calculate unit load for the case of LID application.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.6
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• pp.396-402
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• 2009

Recently many efforts have been carried out on the development of energy-efficient and environment-friendly systems in order to preserve natural environment and to reduce environmental loads in the branch of the urban planning and the building design. In this study, a mathematical method was developed and a numerical analysis was carried out with various parameters to provide substantial data for optimal design and operation of urban energy supply systems. Components of the system and their specifications, such as a co-generation system and other heating and cooling systems, could be obtained through this analysis for various resource and energy requirements in urban area. In this study, the system constituents and operating characteristics, and their economic performances such as the value of objective function, the amount of energy consumption were discussed for various load patterns and power load ratios. Also, it turns out that the optimal energy supply system can save energy by $10{\sim}20%$ in comparison with the conventional energy supply system.