• Earthquakes and Structures
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• 제12권2호
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• pp.177-189
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• 2017

For energy-based seismic design, a simplified normalized cumulative hysteretic energy spectrum proposed for obtaining hysteretic energy as energy demand is the main objective in this paper. The dimensionless parameter, ${\beta}_{Eh}$, is presented to express hysteretic energy indirectly. The ${\beta}_{Eh}$ spectrum is constructed directly through subtracting the hysteretic energy of single degree-of-freedom (SDOF) system energy equation. The simplified ${\beta}_{Eh}$ spectral formulation as well as pseudo-acceleration spectrum of modern seismic provisions is developed based on the regression analysis of the large number of seismic responses of SDOF system subjected to earthquake excitations, which considers the influence of earthquake event, soil type, damping ratio, and ductility factor. The relationship between PGV and PGA is established according to the statistical analysis relied on a total of 422 ground motion records. The combination of ${\beta}_{Eh}$ spectrum and PGV/PGA equation allows determining the cumulative hysteretic energy as a main aseismic design indicator.

• 한국태양에너지학회 논문집
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• 제37권3호
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• pp.23-32
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• 2017

This paper presents losses comparison and analysis results for different types of fault modes of grid-connected photovoltaic system generated for long-term operation. The approach of losses comparison and analysis by faults is to identify relationship between measured and estimated values of five loss factors which are quantified from irradiance to system output power. This paper presents the symptom results for faults such as snow, shading, sensor defect, blackout, soiling and so on from three years or more monitored data. These results will indicate that it is useful to develop fault detection and diagnosis tool to enhance capacity factor and save operation and maintenance cost of grid-connected photovoltaic system in the field.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.516-519
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• 2003

3kW photovoltaic (PV) systems and data acquisition system are constructed for performance analysis of PV system at field demonstration test center (FDTC) of Korea. As climatic and irradiation conditions are varied, the performance characteristics of PV system are collected and analyzed in data acquisition system. From these results, the performances of gird-connected power conditioning system (PCS) fur PV system have been evaluated and analyzed. Furthermore, performance indices of grid-connected PCS e.g. output power, efficiency, loss factor, and the other index at the site are reviewed.

• 한국환경교육학회지:환경교육
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• 제19권3호
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• pp.102-113
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• 2006

The purpose of this study is to devise proper plans for sustainable energy management in schools through applying school eco-audit to energy field. This study is performed by literature review and the analysis of case study. This study analyzes the energy-saving model school according to the three cores of eco-audit such as school administration system, teaching-learning method, and ecological policy, and the result of the study is as followings. First, according to the analysis of school administration system for energy education programs, the participation of all the school staff is very low, and the democratic decision-making system is unsatisfactory. Second, according to the analysis of teaching-learning method, the program is mainly managed by teacher-oriented method not by learner-oriented one. The effect on the education of energy-saving program is a little improved in cognitive area, but is insufficient in affective area. Third, in the aspect of the ecological policy, the practical energy-saving effect in schools is unsatisfactory, and shows the difficulty of continuing application of the program. Consequently, it is desirable to integrate the energy-saving program with the eco-audit for sustainable energy management in schools. Implementation of the energy eco-audit in schools for the sustainable development education as teaching-learning method could achieve extended effect for the earth environmental conservation.

• 한국건축친환경설비학회 논문집
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• 제12권6호
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• pp.669-679
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• 2018

Energy consumption savings in buildings should be reviewed in diverse areas such as air conditioning system and lighting responsible for cooling and heating, and energy management systems such as BAS (Building Automation System) and BEMS (Building Energy Management System) are introduced to improve energy consumption efficiency and to promote economic control of related facilities by integrated management of energy generated and consumption in buildings. The measured building of this study uses regenerative geothermal system. Measured values of heat pump and system COP were 4.7 and 4.2 respectively, and they were found to be higher 11.9% and 23.5% than rated values. As a result of analyzing the air conditioning and lighting energy from the first floor to the fourth floor performing the air conditioning, the second and third floors, which have a high frequency of use, are compared with the first and fourth floors 50% higher energy consumption ratio. On the other hand, the general heat storage system uses the nighttime power of the previous day to store heat and use it the next day. The total number of days of abnormal operation during the summer season is 61 days. The electricity cost corresponding to the abnormal operation is 1,840,641 KRW, and the normal operation using the nighttime power is 1,363,561 KRW, which is difference of 477,080 KRW, 35% increase in cost. We will utilize it as the main data of BEMS through analysis of winter operation characteristics as well as summer operation characteristics.

• 대한기계학회논문집
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• 제19권7호
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• pp.1665-1674
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• 1995

An optimum design has been performed to maximize specific energy (SED) of composite flywheel rotor for energy storage system. The flywheel rotor is assumed to be an axisymmetric thick laminated shell with a plane strain state for structural analysis. For the structural analysis the centrifugal force is considered and the stiffness matrix equation was derived for each ring considering the interferences between the rings. The global stiffness matrix was derived by integrating the local stiffness matrix satisfying the conditions of force and displacement compatibilities. Displacements are then calculated from the global stiffness matrix and the stresses in each ring are also calculated. 3-D intra-laminar quadratic Tsai-Wu criterion is then used for the strength analysis. An optimum procedure is also developed to find the optimal interferences and lay up angle to maximize SED using the sensitivity analysis.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.348-353
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• 2011

Recently the renewable energy has been used widely and the importance of renewable sources is bigger than before. So the government enforced a law to the public buildings to install the renewable energy facilities. The capacity of facilities is 5% of total construction cost until April 13, 2011. Since then, the government changed the law from 5% of total construction cost to 10% of predicted energy usage because of the practical use of the renewable energy facilities. So, in this study, the comparative analysis is conducted according to the law to the building installed PV system through the EnergyPlus simulation.

• Nuclear Engineering and Technology
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• 제40권1호
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• pp.87-92
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• 2008

Tokamak reactor system analysis code was developed at KAERI (Korea Atomic Energy Research Institute) and is used here for the conceptual development of a DEMO reactor. In the system analysis code, prospects of the development of plasma physics and the relevant technology are included in a simple mathematical model, i.e., the overall plant power balance equation and the plasma power balance equation. This system analysis code provides satisfactory results for developing the concept of a DEMO reactor and for identifying the necessary R&D areas, both in the physics and technology areas for the realization of the concept. With this system analysis code, the performance of a DEMO reactor with a limited extension of the plasma physics and technology adopted in the ITER design. The main requirements for the DEMO reactor were selected as: 1) demonstrate tritium self-sufficiency, 2) generate net electricity, and 3) achieve a steady-state operation. It was shown that to access an operational region for higher performance, the main restrictions are presented by the divertor heat load and the steady-state operation requirements.

• 한국태양에너지학회 논문집
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• 제40권2호
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• pp.1-10
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• 2020

Korea government published renewable energy obligation policy that public building must be supplied some part of total consumption energy (2019: 27%, 2020: 30%). RETScreen is freely available global energy tool that developed by Canadian National Energy Laboratory to quantify energy saving to compare conventional system. This program can be performed energy modeling, cost analysis, greenhouse gas emission analysis and financial analysis. In this study, GSHP (Ground source heat pump) heating and cooling system were studied for the energy deliverly and ROI (Return On Investment) in an office building. Three cases were studied according to the number of HP (Heat pump) units for the 1,000㎡ office building located in Daejeon. Results indicated that the energy delivery of the case 1 (1 HP unit) covered 57% of the office building heating and cooling energy consumption. The case 2 (2 HP units) covered 87.8% and the case 3 (3 HP units) covered 96.8% of the office building energy consumption. The ROI of the case 1 indicated 7.9 years. While 8.2 years for the case 2 and 9.7 years for the case 3.

• KIEAE Journal
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• 제15권4호
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• pp.5-11
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• 2015

Purpose: Recently, renewable energy system has been widely used to reduce the energy consumption and CO2 emission of building. A photovoltaic/thermal(PVT) system is a kind of efficient energy uses, which is combined with photovoltaic module and solar thermal collector. PVT system removes heat from PV module by through thermal fluid to raise the performance efficiency of the PV system. However, though PVT system has the merit of the improved efficiency in theoretical approach, there have been few performance analysis for PVT system using the dynamic energy simulation. In this study, in order to establish the optimum design method of this system, simulation was conducted by using individual system modules. Method: For the dynamic simulation, TRNSYS17 was used and local weather data was utilized. Furthermore, the system performance in various installation condition was calculated by case studies. Result: As a result, the amount of electric generation and heat production in each case was found by the simulation. The gap of system performance was also evident according to the installation condition.