• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.2
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• pp.173-179
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• 1998

An experimental study was conducted on the effect of compressor capacity control range of heat pump on the seasonal energy efficiency ratio with variation of the maximum and minimum compressor input frequencies. To obtain seasonal energy efficiency ratio, steady state test at the maximum, minimum and intermediate compressor speed and cyclic test at the minimum compressor speed should be conducted. Maximum input frequency was varied to 95Hz, 105Hz, and 115Hz, and the minimum input frequency was varied to 35Hz, 45Hz, and 55Hz. The seasonal energy efficiency ratio increased as the input frequency of the compressor decreased. The maximum input frequency had only slight effects on the SEER.

• KIEAE Journal
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• v.13 no.2
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• pp.21-26
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• 2013

Due to the increasing concerns about the buildings which have affected the global environment, most countries have enacted a regulation for the sustainability of domestic buildings. In 2008, the Korean government started to enact a regulation of apartment and office buildings for energy saving. Many research on the sustainable apartment building focuses on $84m^2$ or larger type in response to market demand; therefore, small size type such as $46m^2$ type needs to be researched. In addition, the research on the orientation and window to wall ratio of the building have been separately studied as a means of energy reduction; therefore, the research on correlation of the orientation and window to wall ratio hasn't been fully explored yet. This paper analyzes the energy demand of the apartment building as the change of orientation and window to wall ratio among $46m^2$ and $84m^2$ type. In conclusion, when reducing the window to wall ratio, energy demand was reduced, except when the orientation of the building was between from +10 to -20 from the south.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.2
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• pp.8-17
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• 2012

The objective of this study is to perform an analysis of the heat(heating and cooling) and lighting energy consumption according to the window area ratio and the application of horizontal louver, which is external shading device installed for the purpose of energy savings in office buildings. For this, a building was chosen as a typical example, and the heat and lighting energy consumption was calculated by using the daylight and building energy analysis simulation. The results showed that the total energy consumption, when the lighting control was applied, was reduced by an average of 11.49[%] compared to when there was no lighting control. The smaller the glazing ratio is, the less the total energy consumption is. Also, the application of the horizontal louver increases the total energy consumption under the same condition of glazing ratio.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.469-476
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• 2001

The Ν-value in the standard penetration test(SPT) is affected by the magnitude of the rod penetration energy transmitted from the falling hammer as well as the geotechnical characteristics of the ground. Understanding of the striking energy efficiency in the SPT equipment is getting important for that reason. The energy efficiencies of the doughnut hammer with the hydraulic lift system and the automatic trip hammer system were investigated through field tests using the instrumented rod and wave-signal acquisition systems including the pile driving analyzer(PDA) . The rod energy ratio, ΕR$\_$r/ was defined as the ratio of the energy delivered to the drilling rod to the potential free-fall energy of the hammer. It appears that the type of the hammer and lift/drop system had a strong influence on the energy transfer mechanism and ΕR$\_$r/ also varies according to the energy instrumentation system and the analysis methods.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.71-78
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• 2002

The N-value from the standard penetration test(SPT) is affected by the magnitude of the rod penetration energy transmitted from the falling hammer as well as the geotechnical characteristics of the ground. Understanding of the striking energy efficiency in the SPT equipment is getting important for that reason. The energy efficiencies of the various type of equipment were investigated through field tests using the instrumented rod and wave-signal acquisition systems including the pile driving analyzer(PDA). The rod energy ratio, ERr was defined as the ratio of the energy delivered to the drilling rod to the potential free-fall energy of the hammer. It appears that the type of the hammer and lift/drop system had a strong influence on the energy transfer mechanism and ERr also varies according to the energy instrumentation system and the analysis methods.

• 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 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.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.43-48
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• 1998

A short-cut equation for the calculation of the air ratio in the case of firing gases containing incombustibles has been derived on the basis of mass balances. The new equation requires the oxygen concentration and the amount of carbon dioxide in the combustion gas, theoretical oxygen and air requirements, and the content of incombustibles other than carbon dioxide in the fuel for the air ratio calculation. By using the equation, a theoretically correct calculation of the air ratio has been enabled.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.4
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• pp.215-224
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• 2009

Analysis for various driven nozzle position changes. The analysis was done for different Reynolds number in entrance region of jet-pump and for several diameter ratios of driven nozzle. (1) The largest absorption energy was found at the point s=1 in condition of diameter ratio 1:3.21 and point s=0.5 in condition of diameter ratio 1:2.25. (2) The absorption energy was not related to the change of entrance velocity and the driven nozzle position having the largest absorption energy was function for cross section ratio. (3) As the position of driven nozzle moves to the downstream, the absorption energy gets weaker. Because the energy from swirl was lost at the cross section gets smaller. (4) As the position of driven nozzle moves to the downstream, the injection energy leans to the upper direction wall and as the Reynolds number increase, the lean phenomenon is more distinct. (5) The flow quantity of driven nozzle, the diameter ratio 1:3.21, was 32% higher than that of 1 : 2.25 and as the inlet velocity gets faster the efficiency decreased. And as the cross section of the driven nozzle increases.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.519-524
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• 2004

This study is concerned with the braking distance estimation using frictional energy rate. First, steady state rolling analysis is performed, and using this result, the braking distance is estimated. Dynamic rolling analysis during entire braking time period is impratical, so that this study divides the vehicle velocity by 10km/h to reduce the analysis time. The multiplication of the slip rate and the shear stress provides the frictional energy rate. Using frictional energy rate, total braking distance is estimated, In addition, ABS(Anti-lock Brake System) is considered, and two type of slip ratios are compared, One is 15% slip ratio for the ABS condition, and the other is 100% slip ratio which leads lo the almost same braking distance as the elementary kinematic theory. A slip ratio is controlled by angular velocity in ABAQUS/Explicit, A 15% slip ratio gives the real vehicle's braking distance when the frictional energy occurred al disk pad is included. Disk pad's frictional energy rate is calculated by the theoretical approach.