• KIEAE Journal
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• v.13 no.4
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• pp.55-62
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• 2013

Korea Government have carried out various policies to reduce the energy consumption that cause the global warming and environmental pollution. Energy consumption of buildings in Korea has reached 24% of total energy quantities and energy consumption of apartment has been continuously increasing. It has executed the building energy efficiency rating system and energy performance assessments and certification systems have been in force to save energy consumption of buildings. Therefore, this study tried to asset the energy performance of apartment according to the shapes of unit plan, and then to evaluate the energy performance of apartment according to altering balcony area into living area in the unit plan of apartment and thus, to present the effective unit plan to reduce the energy consumption. According to the results, in case of standard unit plan, the 3Bay and 4Bay unit plans showed more effective energy consumption than the 2Bay unit plan, respectively, 5%, 6%, and in case of extended unit plan, respectively, 2%, 5%. Compared the energy efficiencies of the standard unit plan to the extended unit plan, the standard one showed more effective energy consumption than the extended one, respectively, 2% in case of the 2Bay and 4Bay unit, 5% of the 3Bay unit.

• Journal of Power Electronics
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• v.15 no.4
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• pp.1131-1138
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• 2015

This study presents an input-powered high-efficiency interface circuit for energy harvesting systems, and introduces a zero standby power design to reduce power consumption significantly while removing the external power supply. This interface circuit is composed of two stages. The first stage voltage doubler uses a positive feedback control loop to improve considerably the conversion speed and efficiency, and boost the output voltage. The second stage active diode adopts a common-grid operational amplifier (op-amp) to remove the influence of offset voltage in the traditional comparator, which eliminates leakage current and broadens bandwidth with low power consumption. The system supplies itself with the harvested energy, which enables it to enter the zero standby mode near the zero crossing points of the input current. Thereafter, high system efficiency and stability are achieved, which saves power consumption. The validity and feasibility of this design is verified by the simulation results based on the 65 nm CMOS process. The minimum input voltage is down to 0.3 V, the maximum voltage efficiency is 99.6% with a DC output current of 75.6 μA, the maximum power efficiency is 98.2% with a DC output current of 40.4 μA, and the maximum output power is 60.48 μW. The power loss of the entire interface circuit is only 18.65 μW, among which, the op-amp consumes only 2.65 μW.

• The Journal of Economics, Marketing and Management
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• v.11 no.2
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• pp.13-22
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• 2023

Purpose: The purpose of this study is to examine the policy implications of establishing a compact city in Seoul, analyzing whether it is an appropriate and efficient eco-friendly housing supply alternative. Research design, data, and methodology: The analysis criteria include efficiency, safety, and comfort, with efficiency encompassing economic, energy, and public transport links' efficiency. Safety and comfort are aspects of eco-friendliness, housing safety, and improvement in living environments. Results: In terms of economic efficiency, compact cities are a less expensive option than purchasing land for housing construction. To increase energy efficiency, we plan to adopt eco-friendly energy sources. Transportation efficiency is high in locations near public transport stations. To enhance safety and comfort, we intend to create large-scale parks and forests in Seoul. To ensure residential safety, measures will be taken to reduce road vibration, vehicle noise, and scattering dust. Conclusions: Selecting an appropriate location that provides convenient public transportation is essential for creating a compact city for housing in a large city. Combining a compact and smart city is necessary, and implementing smart technologies is needed to prevent dust, noise, and vibrations, which are undesirable in a residential environment.

• Journal of the Korean Wood Science and Technology
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• v.44 no.6
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• pp.821-827
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• 2016

This study evaluates the economic feasibility of industrializing fluidized bed dryer for wood particles. The theoretically required heat energy and energy efficiency were evaluated using a pilot scale fluidized bed dryer. When Mongolian Oak wood particles with 50% initial moisture content were dried in the fluidized bed dryer with air of $70^{\circ}C$ air circulating at 1.1-1.3 m/s for 30 minutes, the total theoretically required heat energy was 2,177 kJ. Of this, 1,763 kJ (approximately 81.0%) was used to heat the air flowing in from outside the dryer and 386 kJ (approximately 17.7%) was used to heat and remove water from the wood particles. Actual energy consumed was 7,560 kJ, giving energy efficiency of 28.8%. Thus, to industrialize a drying method such as fluidized bed drying, where the dryer volume is significantly larger than the volume of wood particles, it is necessary to minimize energy loss and maximize energy efficiency by designing the dryer size considering the amount of wood particles and choosing a suitable air circulation rate.

• Journal of the Korean Geotechnical Society
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• v.21 no.9
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• pp.5-12
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• 2005

SPT hammer energy and its delivery are hon to influence the N value. The SPT hammer energy is classified into theoretical energy, velocity energy, rod energy and dynamic efficiency. In this study, the rod energy and the velocity energy are measured directly by PDA and Digital Line-Scan Camera which are most widely used type of SPT apparatus in Korea. The Dynamic efficiency is calculated through measured data. As the results of this study, the averages of rod energy ratio of donut, safety and automatic hammer are measured at 49.57, 61.60, and at $87.04\%$ by FV method. The averages of hammer velocity of donut, safety and automatic hammer are measured at $3.177{\pm}0.872$, $3.385{\pm}0.681$, and at $3.651{\pm}0.550$ m/s by Digital Line-Scan Camera, with the dynamic efficiencies at 0.732, 0.801, and 0.973 respectively.

• KIEAE Journal
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• v.13 no.3
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• pp.71-78
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• 2013

A need for building energy efficiency is on the issue since energy demand in the building stock in Korea represents about 24% of the final energy consumption. As a way of improving the thermal performance of buildings for reducing maintenance costs and environmental conservation, a lot of effort is shown to improve the building energy efficiency by applying improvement of envelope insulation performance for buildings whose energy efficiency is low relatively through the remodeling. The windows of building envelopes are areas that lead to the biggest heat loss in the building. So windows are considered to be the primary target of energy efficiency in remodeling and various studies for windows have been done. Currently, however, only U-factor and airtightness of windows performance are regulated. Window wall ratio(WWR) and solar heat gain coefficient(SHGC) of windows are not considered when conducting the remodeling. In this study appropriate performance of windows(U-factor and SHGC) for existing residential is proposed according to the window wall ratio by using EnergyPlus. As the results of this study, the U-factor of windows representing the maximum energy savings is $1.0W/m^2K$ but in case of SHGC, the values that indicate the maximum energy savings are different depending on the window wall ratio. Therefore, when conducting the remodeling of windows, to determine energy efficiency by considering only the U-factor is inadequate so it is necessary that appropriate windows are applied to buildings by considering window wall ratio and windows properties(U-factor and SHGC).

• Journal of Energy Engineering
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• v.16 no.4
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• pp.164-169
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• 2007

The decrease in the summer peak electric load in our country is very important. The government has arranged and implemented a lot of support policies and statutes to decrease the peak electric load. And the ice-thermal-energy-storage system is known as one of the alternatives. The purpose of this paper is to evaluate the performance and the total efficiency of its storage tank, conducting the charging operation, the parallel operation and the single operation of a storage tank. The thermal energy density stored and discharging efficiency of a storage tank and the efficiency of total energy utilization of system are $18.4\;USRT-h/m^3$, 96.2% and 2028.7 kcal/kWh under the operation of design condition. When the storage tank is supplied more ice thermal energy than design condition, it is estimated that the efficiency of system are lower than the design condition by the supercooled effect.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.5
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• pp.1761-1777
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• 2021

An image with infrared features and visible details is obtained by processing infrared and visible images. In this paper, a fusion method based on Laplacian pyramid and generative adversarial network is proposed to obtain high quality fusion images, termed as Laplacian-GAN. Firstly, the base and detail layers are obtained by decomposing the source images. Secondly, we utilize the Laplacian pyramid-based method to fuse these base layers to obtain more information of the base layer. Thirdly, the detail part is fused by a generative adversarial network. In addition, generative adversarial network avoids the manual design complicated fusion rules. Finally, the fused base layer and fused detail layer are reconstructed to obtain the fused image. Experimental results demonstrate that the proposed method can obtain state-of-the-art fusion performance in both visual quality and objective assessment. In terms of visual observation, the fusion image obtained by Laplacian-GAN algorithm in this paper is clearer in detail. At the same time, in the six metrics of MI, AG, EI, MS_SSIM, Q_abf and SCD, the algorithm presented in this paper has improved by 0.62%, 7.10%, 14.53%, 12.18%, 34.33% and 12.23%, respectively, compared with the best of the other three algorithms.

• Journal of the military operations research society of Korea
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• v.35 no.2
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• pp.99-117
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• 2009

Energy is essential factor of production for a firm to produce goods and services. If so, what is the condition of maintaining profit of a firm when energy price is going up? In conclusion, the condition is that the rate of productivity improvement should be greater than the rate of energy price increase. To put this concretely, when the elasticity of energy price as to the productivity improvement is greater than the weight of the energy cost on to the total revenue of the firm, the firm can escape the negative effect of energy price increase. This is that, saying that once more, the firm have to reduce the energy cost or promote energy efficiency to maintain appropriate or sufficient profit when energy price is going up fast. Therefore, in this study we will analyze the effect of the oil price increase on the energy saving investment and that of energy saving investment on the energy efficiency in the field of Korean manufacturing industry. In doing so, this study could show that the effect of energy price increase on the energy efficiency of the firm and the factor of that mechanism.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.19 no.1
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• pp.1-13
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• 2023

Many government in the world have conducted building energy performance certification program to reduce building energy consumption. In this study, a reference building and its HVAC system was modeled, and the energy load and consumption were estimated by the ECO2 program. The software is a simple building energy simulation program based on monthly calculated method. The building energy efficiency rating the the reference building was 1+ under baseline condition. The simulation results showed that the insulation performance slightly affected building energy load and consumption, but light density had a significant effect on them. The application of geothermal heat pumps gave improvement of building energy efficiency rating but it could not make it possible to get zero energy building(ZEB) certification. The ZEB 5 certification could be achieved by using photovoltaics, however getting better grade was difficult. The simulation results showed that the ZEB 4 certification, one grade higher than ZEB 5, could be attained by using more than one renewable energy source such as geothermal and solar energy in this study.