• Environmental and Resource Economics Review
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• v.19 no.1
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• pp.129-157
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• 2010

This paper is intended to evaluate energy efficiency policy in demand side, to assess the residential sector's energy efficiency policy and to analyze the system of energy efficiency practices. We examined residential energy consumption over the period 1990~2006. The decomposition method in the analysis was a logarithmic mean Divisia index (LMDI) techniques to decompose changes in energy intensity. First of all, the energy use in residential sector was adjusted to correct weather-induced variations in energy consumption, because adjustments for normal weather patterns facilitated inter-temporal comparison of intensity. The analysis on the residential sector shows that the overall energy intensity of the residential sector declined at an average 1.0% per year, while the structure effect increased by 1.8% per year, and the activity effect increased by 0.7% per year. In other words, the decline of floor space, number of household, and appliance ownership per capita has an effect on increase in residential consumption. The improvement in energy efficiency had strong contribution on the decrease of energy consumption. We find that the general results of analysis on residential energy are similar to those of IEA. The energy efficiency policy in residential sector is assessed to obtain some results during 1990~2006. In residential sector, structural variables such population per household, diffusion of appliance and activity factor such as population contributed to the increase of energy consumption while energy intensity effect induced the decrease of energy consumption. These findings are consistent with international trend as well as our prior expectation.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1676-1681
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• 2004

The main reason for applying positive pressure variable clearance packing in fossil power plant is high efficiency and energy saving movement in the government. This study intends to analyze the turbine efficiency through the shaft packing improvement in thermal power plant and makes its comparison to that of the each packing type

• The Transactions of the Korean Institute of Electrical Engineers
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• v.31 no.8
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• pp.46-53
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• 1982

When an induction motor is lightly loaded, the efficiency can be very substantially improved by controlling the air gap flux. Thus in the system which requires constant speed under either normal load or light load, it is possible to save energy by means of controlling the air gap flux. In this paper, the required relationships between stator current and rotor slip frequency for optimal efficiency control is derived and the improved control loop is suggested.

• Journal of Energy Engineering
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• v.28 no.1
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• pp.37-44
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• 2019

Domestic buildings account for 25% of national greenhouse gas emissions and 20% of energy consumption, so energy efficiency improvement of buildings is recognized as the main target of national energy demand management. To improve the energy efficiency of the building, policies are implemented by preparing "zero-energy building national roadmaps" and enhancing the efficiency of national energy demand management through early activation as a result of expansion of the mandatory zero-energy building. Also, there is a growing need to verify the performance of energy savings after the construction is completed. Therefore, methods for evaluating energy performance of buildings should be suggested. This paper aims to develop and present methods for verifying energy performance of Zero Energy School, which can be applied internationally, by visiting domestic schools on-site at the same time as international standards and guidance analysis.

• Journal of the Korean Solar Energy Society
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• v.30 no.1
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• pp.50-60
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• 2010

Today, the amount of energy consumption in the university campuses is huge. The effort for the energy consumption reduction in university campuses is certainly needed by the following reason; first, contribution to the greenhouse gas discharge reduction demand. Second, energy cost reduction in university campus. Third, contribution to the improvement of the social awareness as the maximum higher educational institutions. The energy consumption analysis of current situation has to be executed for the energy consumption reduction in university campus. The energy reduction possibility in which it exists in university campuses can be understood through the energy consumption analysis. And the application is possible as fundamental data of the policy establishment for the effective energy reduction in university campuses. Especially, the best way to reduce the energy consumption in university campuses that is the energy consumption reduction of buildings. Accordingly, this study derived the plans for improving the performance of energy in the university building by analyzing case study, so this study analyzed the performance of energy for the university building through VE, a program for the analysis of building energy. Based on this result, this study classified the plans improving the efficiency of energy in university building into the plan for passive control and active control respectively, and suggested some concrete plans, and finally evaluated the performance of decreasing energy consumption for each plan.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.3
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• pp.13-20
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• 2021

The capacity optimization of the heat exchanger of the TEM dehumidifier was performed through numerical analysis. If the ratio of the size of heat exchangers on the cold and hot surfaces of the TEM is not appropriate, the larger the size of the heat exchanger results the lower performance and efficiency. Optimizing the ratio of heat exchangers on the cold surface of TEM can improve the performance and the efficiency compared to when the ratio is 50%. The optimal proportion of cold surface heat exchangers is inversely proportional to the sum of the size of the heat exchangers on the cold and hot surfaces. When the optimum ratio of cold surface heat exchanger was applied, the larger the sum of size of the two heat exchangers results the greater the improvement of the performance and efficiency, compared to when the ratio of cold surface heat exchangers is 50%.

• Journal of Biosystems Engineering
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• v.9 no.2
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• pp.65-73
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• 1984

While most of researches on the performance of high temperature grain dryer have dealt mainly with improving dryer capacity and drying speed during the last twenty years, energy efficiency, in fact, has not been emphasized. Current fuel supplies and energy cost have shifted the emphasis to reducing the energy consumption for grain drying while maintaining dryer capacity and grain quality. Since the energy input for drying is relatively large, the recovery and reuse of at least part of the exhaust energy can significantly reduce the total energy consumption in existing drying systems. Unilization of exhaust heat in grain dryer either through direct recycling or by a thermal coupling in heat exchanger have been subject of a number of investigators. However, very seldom research in Korea has been done in this area. Three drying tests(non-recycling, 0.22 recycle ratio, and 0.76 recycle ratio)were performed to investigate the thermal efficiency and heat loss factors of continuous flow type dryer, and to analyze the effect of recycle ratio (weight of exhaust air recycled/total weight of input air) on the energy requriements for rough rice drying. The test results showed that when the exhaust air was not recycled, the energy lost from furnace was 15.3 percent of input fuel energy, and latent and sensible heat of exhaust air were 61.4 percent and 11.2 percent respectively. The heat which was required in raising grain temperature and stored in dryer was relatively small. As the recycle ratio of exhaust air was increased, the drying rate was suddenly decreased, and thermal efficiency of the kerosene burner was also decreased. Drying test with 0.76 recycle ratio resulted in 12.4% increase in fuel consumption, and 38.4% increase in electric power consumption as compared to the non-recycled drying test. Drying test of 0.22 recycle ratio resulted in 6.8% saving in total energy consumption, 8.0% reduction in fuel consumption, and 2.5% increase in electric power consumption as compared to the non-recycled drying test.

• Journal of Korean Society on Water Environment
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• v.33 no.1
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• pp.63-69
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• 2017

Small size privately owned wastewater treatment plants have been difficult to treat their wasted sludge and maintain steady effluent quality compared with publicly owned wastewater treatment plants. Therefore, this study has focused on treatment efficiency enhancement, specially nitrogen removal efficiency by recycling dewatering filtrate as an alkalinity additive from filter press using $CaCO_3$. As the result, it was found that the optimal mixing ratio between the excess sludge and $CaCO_3$ was 1:2. The major operation parameters such as specific substrate utilization rate, specific nitrification rate, and specific denitrification rate were also improved 64% ($0.048-0.079mg\;BOD_5/mg\;MLVSS{\cdot}day$), 35% ($0.020-0.027mg\;NH_3-N/mg\;MLVSS{\cdot}day$) and 68% ($0.051-0.086mg\;NO_3{^-}-N/mg\;MLVSS{\cdot}day$), respectively, after the adoption of new methods. Therefore, both the problem of sludge treatment at small scale plants and the need for efficiency improvement could be solved.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.1
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• pp.150-153
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• 2015

An energy-efficient 64-bit prefix adder is proposed for micro-server processors based on both semidynamic and bypassing structures. Prefix adders consist of three main stages i.e. propagate-generate (PG) stage, carry merge (CM) tree, and sum generators. In this architecture, the PG and CM stages consume most of the power because these are based on domino circuits. This letter proposes a semidynamic PG stage for its energy-efficiency. In addition, we adopt the bypassing structure on the CM tree to reduce its switching activity. Experimental results show 19.1% improvement of energy efficiency from prior art.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.204-205
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• 2016

Human power is not dependent on other energy sources, but rather is a source of power for ourselves. Human power, the cleanest energy in the world, can be our future. Therefore, we should be interested in sustainable alternative energy. This paper solves the uneven power generation by utilizing the energy storage capability of the flywheel. Therefore, it improved the efficiency by 5% compared to the existing generation method. DC generators produce power at variable speed operation. The constant voltage was generated from the DC-DC converter to the duty ratio control. Therefore, the charging efficiency is improved by 5% by the constant voltage charging of the battery. And it can suppress the decrease of the output due to the circulation current due to the deviation of the output voltage in parallel operation of the pedal generator.