• Korean Journal of Construction Engineering and Management
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• v.14 no.4
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• pp.55-64
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• 2013

As GHG target management is introduced in Korea, designated establishment takes responsibilities to reduce more than 30% of expected GHG emission until 2020. Although decreasing GHG has been requested to universities which consume great amount of energy, there are difficulties to apply high cost countermeasures. Therefore, this research suggest a low cost, easily-applicable energy saving method, and derive potential GHG reduction amount in the case of SNU, Kwan-ak campus. First of all, 11 rooms of different use were chosen as the samples, and energy consumption in each room was measured. Standard models for each room were built through researching on the electric devices in each room. Moreover, energy consumption was computed for each devices through analyzing the pattern of electricity consumption. 32 GHG reduction technology and action program were chosen, and they were applied to the standard models for individual rooms. Through multiplying energy reduction rate of each program to energy consumption of each electric device, maximum energy reduction of each electric device is derived. Through that, Maximum GHG reduction for individual rooms and each month and the total GHG reduction capacity of Kwan-ak campus were computed. It was found out that approximately $5,311tCO_2$-eq can be reduced, when reduction technology and action program suggested by this research are applied. It appeared 24.48% of requested reduction amount to SNU can be reduced, till 2016.

• Korean Management Science Review
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• v.30 no.1
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• pp.139-148
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• 2013

A nuclear energy has been one of the most important sources to securely supply electricity in South Korea. Its weight in the national electricity supply has kept increasing since the first nuclear reactor was built in 1978. The country relies on the nuclear approximately 31.4% in 2012 and it is expected to increase to 48.5% in 2024 based on the long-term electricity supply plan announced by the Korean government. However, Fukushima disaster due to 9.0 magnitude earthquake followed by the tsunami has raised deep concerns on the security of the nuclear power plants. The policy makers of the country are much interested in analyzing the cost structure of the power supply in the case that the nuclear is diminished from the current supply portion. This research uses a stochastic model that aims to evaluate the long-term power supply plan and provides an extensive cost analysis on the changes of the nuclear power supply. To evaluate a power supply plan, the research develops a few plausible energy mix scenarios by changing the installed capacities of energy sources from the long-term electricity supply plan. The analyses show that the nuclear is still the most attractive energy source since its fuel cost is very much stable compared to the other sources. Also the results demonstrate that a large amount of financial expenditure is additionally required every year if Koreans agree on the reduction of nuclear to increase national security against a nuclear disaster.

• Journal of Korea Water Resources Association
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• v.44 no.10
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• pp.809-817
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• 2011

We analyzed various cost components for approximately 40 small-scale island desalination plants operated by K-water. A significant factor affecting desalination cost was found, and we proposed a way to reduce desalination costs. All plants considered were reverse osmosis (RO) facilities. TDS concentrations of feed water varied from less than 1,000 mg/L (practically considered freshwater) to over 30,000 mg/L (nearly seawater). Analysis of desalination costs from 2005 to 2009 indicated that maintenance, labor, and energy were the three biggest components that accounted for 50.6%, 36.9% and 7.8%, respectively. It was well known that TDS of feed water directly affected energy needed for RO process. In this study we found that maintenance cost was also directly related to feed water TDS. This finding indicated that lowering feed water TDS might result in significant desalination cost reduction.

• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.194-198
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• 2012

Crystalline silicon solar cell remains the major player in the photovoltaic marketplace with 80% of the market, despite the development of various thin film technologies. Silicon's excellent efficiency, stability, material abundance and low toxicity have helped to maintain its position of dominance. However, the cost of silicon materials remains a major barrier to reducing the cost of silicon photovoltaics. Using the crystalline silicon wafer with thinner thickness is the promising way for cost and material reduction in the solar cell production. However, the thinner the silicon wafer is, the worse bow phenomenon is induced. The bow phenomenon is observed when two or more layers of materials with different temperature expansion coefficiencies are in contact, in this case silicon and aluminum. In this paper, the solar cells were fabricated with different thicknesses of Al layer in order to reduce the bow phenomenon. With less amount of paste applications, we observed that the bow could be reduced by up to 40% of the largest value with 120 micron thickness of the wafer even though the conversion efficiency decrease by 0.5% occurred. Since the bowed wafers lead to unacceptable yield losses during the module construction, the reduction of bow is indispensable on thin crystalline silicon solar cell. In this work, we have studied on the counterbalance between the bow and conversion efficiency and also suggest the formation of enough back surface field (BSF) with thinner Al layer application.

• Architectural research
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• v.19 no.4
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• pp.101-108
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• 2017

The use of the air conditioner is increasing due to the rise of the outdoor temperature during summer, and the problems of the fire and the cooling performance deterioration are caused due to lack of maintenance of the outdoor unit. In particular, overall performance of cooling system and efficiency in outdoor units have been degraded due to an intake of high-temperature outdoor air thereby increasing cooling energy and operating cost. Thus, this study aimed to increase efficiency of outdoor units by evaporating and cooling intake air through mist spray at the intake port surface in the outdoor unit. The measurements results showed that total power consumption of misting outdoor unit compared to that of conventional outdoor units was reduced by 21% approximately, and total power consumption of the entire system including pump was reduced by 16.7%. In addition, the operating cost including water use was reduced by 13.5% approximately. In summary, if a mist-spray nozzle kit is installed in air-cooled outdoor units, the reduction in the usage of cooling energy and operating cost will be achieved without replacement of existing cooling systems or a large scale of repairs.

• Korean Journal of Construction Engineering and Management
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• v.20 no.5
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• pp.21-30
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• 2019

Environmental and energy issues such as abnormal climate and depletion of fossil fuel due to global warming have emerged as a critical task to threaten human survival. As a result, interest in the Zero Energy Building is increasing as it is an innovative building that can significantly contribute to building energy reduction and greenhouse gas reduction. In the market, however, the added cost of construction is a major stumbling block to the revitalization of the Zero Energy certification. In this study, general private apartment complexes were selected for research, detailed elements for Zero Energy certification were presented based on the construction criteria for eco-friendly houses from the initial design stage, and the cost efficiency analysis of the components for certification were presented. It has been analyzed that only Grade 3 certification can be implemented in apartments due to technical level and physical limitations. Also, after reviewing the cost trend during the lifecycle cost, all expenses can be recovered within 13 years after completion only in the case of grade 5 of the Zero Energy Building. The additional costs proposed in the present study are reflected appropriately in the review of projects for apartments scheduled for order in the future to contribute to the revitalization of the Zero Energy Building certification.

• Current Photovoltaic Research
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• v.6 no.2
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• pp.49-55
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• 2018

Recently solar cell industry needs the optimal design of Czochralski process for low cost high quality silicon mono crystalline ingot. Because market needs both high efficient solar cell and similar cost with multi-crystalline Si ingot. For cost reduction in Czochralski process, first of all energy reduction should be completed because Czochralski process is high energy consumption process. For this purpose we studied optimal water-cooling tube design and simultaneously we also check the quality of ingot with Von mises stress and V(pull speed of ingot)/G(temperature gradient to the crystallization) values. At this research we used $CG-Sim^{(R)}$ S/W package and finally we got improved water-cooling tube design than normally used process in present industry. The optimal water-cooling tube length should be 200mm. The result will be adopted at real industry.

• Journal of Energy Engineering
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• v.15 no.1 s.45
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• pp.14-22
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• 2006

Various pros and cons are raised as to the nuclear and renewable power portions. In order to generate scientific, objective, and comparative data, this study reviewed energy policies of some countries and derived 34 possible energy mix scenarios depending on the nuclear portion, the renewable portion and the make-up power sources. For each scenario, the unit electricity cost was calculated using the BLMP (Base Load Marginal Price) and SMP (System Marginal Price) methodology, which is currently adopted in Korean electricity market. The unit electricity cost for the current energy mix was 22.18 Won/kWh and those fir other scenarios spreaded from 19.74 to 164.07 Won/kWh excluding the transmission costs and profits of the electric utility companies. Generally, the increased nuclear power portion leads reduction in the unit electricity cost while the trend is reversed in the renewable power portion. Notable observation is that when the renewable power portion exceeds 20%, as the scenario cannot enjoy the benefit of cheap base load, the unit electricity cost at low demand time zone is increased.

• Solar Energy
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• v.8 no.2
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• pp.73-76
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• 1988

Thick films based on the mature crystalline silicon technology are expected to exhibit eversmaller cost reduction. The thin-film-based technology is, however, expected to exhibit a much sharper drop in cost as it develops. In this report, technology and recent R & D of thin film solar cell, such as amorphous silicon, cadnium telluride, copper indium diselenide and gallium arsenide, are described. Perspectives of world photovoltaic market and solar cell price are also described.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.867-876
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• 1993

This study was investigated to evaluate whether brown rice drying could reduce the rice production cost. Characteristics of brown rice drying was experimentally determined. With brown rice drying, the higher energy efficiency could be obtained. Therefore, this method is effective to cost reduction . However, there are some problems , for example occurrence of fissuring and preservation of rice quality.