• Journal of the Korean Society of Industry Convergence
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• v.7 no.3
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• pp.233-240
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• 2004

This paper presents a feasibility study of a fresh air load reduction system by using an underground double floor space The system was introduced into a real building and was examined by the field measurement Judging from the measurements during three years(1999~2001), the state of the system operation was very stable through this period and it was clear that the system contributes to reduction of energy consumption for air-conditioning. Futhermore, a simulation model used the simple heat diffusion equation Was developed to simulate its thermal characteristics and performances The simulations resulted m air temperature in good agreement with the measurements. Also, from the result of numerical analysis, It is clear that the amount of heat supply by using this system is more than the amount of energy loss to the room above it. Therefore, it is concluded that this systems is very useful and the proposed numerical model can be used for the prediction of system thermal performance.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.4
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• pp.331-340
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• 2004

This paper presents a feasibility study of a fresh air load reduction system by using an underground double floor space. The fresh air is introduced into the double slab space and passes through the opening bored into the footing beam. The air is cooled by the heat exchange with the inside surface of the double slab space in summer, and heated in winter. This system not only reduces sensible heat load of the fresh air by heat exchange with earth but also reduces latent heat load of the fresh air by ad/de-sorption of underground double slab concrete. In this paper, we used a model for evaluation of fresh air latent heat load reduction by hygroscopic of air to earth exchange system taking into account coupled heat and moisture transfer of underground double floor space. In conclusion it shows the validity of the proposed method for a design tool and the quantitative effect of the system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.1
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• pp.47-56
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• 2015

Energy consumption in buildings is currently a real problem. That is why both assessment of energy performance and effective energy management including renewable energy system are essential. Thus, this paper focuses on a case study to analyze the energy performance and cooling & heating energy saving of a large scale shopping store in Daejeon city. The reference building is simulated by using TRNSYS dynamic simulation tool to examine its annual energy consumption. For annual energy analysis of building, one year energy consumption is surveyed in the field. The related study is carried out in large scale shopping store to investigate the energy consumption and energy use trend of heating, cooling, hot water, lighting, ventilation, equipments and other. The evaluation of energy performance of the geothermal heat pump system installed in a large scale shopping store is also analyzed by TRNSYS tool. From simulation results, it evaluated that the geothermal heat pump system is effective energy savings method in large scale shopping store.

• Journal of the Korean Solar Energy Society
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• v.35 no.5
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• pp.49-56
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• 2015

In this study a hybrid heating system based on geothermal source and solar heat was developed in order to save energy for greenhouse heating and its field performance was evaluated. Developed system are composed of following parts: water tank, heat exchanger, heat pump, fan coil unit and heat storage unit. The working performance test was carried out in a greenhouse cultivating oriental orchids being managed by $23^{\circ}C$. Field performance test results showed that average heating coefficient of performance ($COP_h$) was 3.4 for the period from mid-January to mid-March 2013. Heating coefficient of performance ($COP_h$) of developed hybrid heat pump system was more sensitive to water tank temperature than outside air temperature. This study showed that developed hybrid heat pump system has a potential to save the heating costs up to 91% compared to conventional agricultural oil heaters.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.287-293
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• 2008

As the instability of international societies on the energy resources has increasingly been deepened due to excessive use of fossil fuels, the importance of energy saving and global environment protection has highlighted, So the interests in environment-friendly and stable new & renewable energy have been dramatically increased. The studies on reconstructing the old-fashioned towns economically, socially and physically have been also significantly increased. In this urban regeneration, renewable-energy using systems were aggressively applied to overcome the energy and environmental problems of the existing towns. There have been many of studies on the compound applications of the renewable-energy using systems in the advanced countries while they are insufficient in Korea. As a preliminary study of urban renewable-energy using system development, this paper surveyed the foreign cases applied to key technologies such as geothermal energy, hydrogen fuel cell and bioenergy among the renewable-energies in urban built environment.

• The Journal of Engineering Geology
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• v.10 no.1
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• pp.39-50
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• 2000

Because of numerous mountain region, agricultural affairs work can't be done without groundwater in Kangwon Do area. Especially to improve high mountain area vegetable quality and raise income offarmers, both of groundwater and hydrothermal system to keep adequate temperature in hot and coldseason have to be developed. Domestic groundwater was developed for the use of agricultural watersince 1960. Exact investigation and control of groundwater are greatly required in utilizing undergroundspace as subway, nuclear power plant, oil and hazardous waste storehouse. Groundwater contaminationowing to industrial irrigation, trash decomposition can have a serious effect on human health and rustof underground building. In this study, global prospecting system are applied to detect groundwater, using electrical, seismic and georadar prospecting method.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.45-50
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• 2015

In Korea ranking sixth out of The world's greenhouse gas emissions, all Korean public buildings have to implement obligatorily renewable energy systems for energy production to reduce the greenhouse gas emissions from the energy consumed in operation, maintenance and management of buildings. The optimum combination and application rates for each energy source emerge from analyzing the trend of previous studies and the energy consumption is simulated by using a dynamic energy simulation program and the initial investment costs, the energy costs, the maintenance costs, the replacement costs emerge based on the calculated result. The result show that the total life cycle cost of 100% gerthermal is the lowest with \ 2,105,974,344 on the analysis results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.2
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• pp.173-182
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• 2005

The Performance of U-tube ground heat exchanger for geothermal heat Pump systems depends on the thermal properties of the soil, as well as grout or backfill materials in the borehole. In-situ tests provide a means of estimating some of these properties. In this study, in-situ thermal response tests were completed on two vertical boreholes, 130 m deep with 62 mm diameter high density polyethylene U-tubes. The tests were conducted by adding a monitored amount of heat to water over a $17\~18$ hour period for each vertical boreholes. By monitoring the water temperatures entering and exiting the loop and heat load, overall thermal conductivity values of grout/soil formation were determined. Two parameter estimation models for evaluation of thermal response test data were compared when applied on the same temperature response data. One model is based on line-source theory and the other is a numerical one-dimensional finite difference model. The average thermal conductivity deviation between measured data and these models is of the magnitude $1\%$ to $5\%$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.5
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• pp.212-217
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• 2014

Recently, the use of renewable energy has been increased due to growing concern on the energy-saving at buildings and the reduction of $CO_2$ emission. In the field of architecture, to reduce the energy consumption of heating, cooling and hot water supply, heat pump systems with renewable energy has been developed and used in various applications. However, there have been many of researches on the large-scale commercial heat pump systems, but the research and the field application of a compact heat pump system is rare. Therefore, in order to develop the compact heat pump for the small-scale residential building, this study conducted the performance test and feasibility study for a hybrid heat pump using the heat source of air, solar and ground. In the results of experiments through a trial product, the average COP of cooling mode with ground heat source was 4.75, and it of heating mode was 4.03. Furthermore, the average COP of cooling mode with air heat source was 2.60, and it of heating mode was 2.92. Finally, payback period of the system was calculated as 9.2 years.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.995-998
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• 2005

This paper proposes a new SoC (System-on-Chip)-based automatic compensation circuit (ACC) for 5GHz low noise amplifier (LNA). This circuit is extremely useful for today's RF IC (Radio Frequency Integrated Circuit) devices in a complete RF transceiver environment. The circuit contains RF BIST (Built-ln Self-Test) circuit, Capacitor Mirror Banks (CMB) and digital processing unit (DPU). The ACC automatically adjusts performance of 5GHz LNA by the processor in the SoC transceiver when the LNA goes out of the normal range of operation.