• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1205-1211
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• 2013

The structural and optical properties of the ZnO, Al-doped ZnO, Ga-doped ZnO, and In-doped ZnO nanorods were investigated using field-emission scanning electron microscopy, X-ray diffraction, photoluminescence (PL) and ultraviolet-visible spectroscopy. All the nanorods grew with good alignment on the ZnO seed layers and the ZnO nanorod dimensions could be controlled by the addition of the various dopants. For instance, the diameter of the nanorods decreased with increasing atomic number of the dopants. The ratio between the near-band-edge emission (NBE) and the deep-level emission (DLE) intensities ($I_{NBE}/I_{DLE}$) obtained by PL gradually decreased because the DLE intensity from the nanorods gradually increased with increase in the atomic number of the dopants. We found that the dopants affected the structural and optical properties of the ZnO nanorods including their dimensions, lattice constants, residual stresses, bond lengths, PL properties, transmittance values, optical band gaps, and Urbach energies.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.3
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• pp.8-16
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• 2014

Heating and hot water supply energy consumption of medium and multi boiler systems applied to military officer housing are compared with in-situ experiment and TRNSYS dynamic simulation program. In a multiple boiler system, small capacity boilers are connected in parallel to meet the required capacity. For handling partial loads, medium capacity boiler relies on on-off control, while multi boiler adopts PI control. Since multi boiler has higher efficiency and better control strategy, the results show that energy consumption can be reduced significantly with the multi boiler system.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.7 no.1
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• pp.59-64
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• 2011

Feasibility study on energy saving system by utilizing exhausted heat from subway, which is one of the unused energy, was carried out. General heat source system using absorption chiller-heater was used for comparing to the energy saving system, and payback period method using initial cost and running cost of two systems, was used to perform economic estimation. Payback period was about ten years, and this period might be shortened if nation's economic support enact.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.9 no.3
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• pp.11-18
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• 2013

Small and medium-size buildings employ a multi-distributed individual air-conditioning system utilizing package air conditioners instead of centralized cooling systems, which can allow easier building management and maintenance along with a diversification of facility use. Inverter driven system heat pumps have been developed to achieve not only easy distribution control allowing free combination of indoor units with different models and different capacities, but also wide applications to an intelligent air conditioning. In this study, the transient performance of a system heat pump was analysed with the variation of compressor speed and EEV openings. The superheat was selected as a control parameter of the system, because the variation of it was consistent with each indoor unit capacity.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.4
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• pp.16-23
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• 2019

Renewable energy systems are essential for the realization of zero energy building (ZEB). Moreover, the integrated system using solar and geothermal energy has been developed for heating, cooling and power of the building. However, there are few studies considering various design factors for system design. In this study, in order to develop the optimal design method for the system, the performance of the system was quantitatively compared and analyzed through dynamic simulation. Moreover, economic analysis was conducted based on the results of system performance. Through the performance and economic analysis results, the optimal design method of the tri-generation system was proposed.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.5 no.2
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• pp.7-12
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• 2009

The fossil fuel has been used as the main resource of national development. Through this process, many environmental problems have happened. For example, we depend 97% energy on import for national spending and the exhaustion of the fossil fuel is at an important issue nowadays. So more people are interested in renewable energy which is more environmental and never be gone. However, the supply doesn't go on smoothly because of some problems such as capital condition, the limitation of geographical features and low technology, etc. In conclusion I'd like to check some policies and support systems about renewable energy first, and then to find problems for adapting other area through the comparison in this thesis.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.1
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• pp.9-17
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• 2019

Reducing global warming potential has become important, and as one of those methods for reducing it, economic evaluation by applying ice thermal storage air conditioning system was performed. The floor area and height of the subject building was assumed $5,000m^2$ and 20 m. Absorption chillerheater system and air source heat pump system was used for comparing to the subject system, and payback period method was used to perform economic evaluation. Although the running cost of ice thermal storage system is reduced compared to two systems, the ratio is not significant compared to the increase of initial construction expenses, and payback period was calculated to be about 7.7 and 79.3 years. However, the heat storage system should be approached from the viewpoint of long term rather than the economic standard in the present standard.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.597-616
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• 2022

The Chungnam basin is a crucial area for studying the Mesozoic crustal evolutionary history of the Korean Peninsula. This study reports the revised geology and new isotopic ages from the northeastern Chungnam Basin based on detailed geological mapping and LA-ICP-MS zircon U-Pb analysis. Our renewed geologic map defines intra-basin, basin-bounding, and basement fault systems closely related to hydrothermal gold-bearing quartz vein injections. Here, we propose the directions of (micro)structural and geochronological future work to address issues on the relationship between the tectonic process, basin evolution, and hydrothermal fluid migration in the southwestern Korean Peninsula.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.190-190
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• 2009

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.1
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• pp.7-13
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• 2014

This study intends to analyse the economical aspect of a GSHP(Ground Source Heat Pump) system compared to the conventional system which is consisted with a boiler and a chiller. This study has simulated four systems in Incheon. It developed and analyzed for applications in a residential and an office building which was based on the hourly EPI(Energy Performance Index, $kWh/m^2yr$). Case 1 is utilizing a boiler and a chiller to meet heating and cooling demand of a house. Case 2 is utilizing the same conventional set up as Case 1 of a office. Case 3 is summation of Case 1(house) and 2(office) systems and loads. And Case 4 is utilizing a GSHP to meet the combined loads of the house and office. The method of the economic assessment has been based on IEA ECBCS Annex 54 Subtask-C SPB(Simple Payback) method. The SPB calculated the economic balanced year of the alternative system over the reference system. The SPB of the alternative systems (GSHP) with 10%, 30% and 50% initial incentive has been calculated as 9.38, 6.72 and 4.06 year respectively while the SPB without initial incentive of systems was 10.71 year.