• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.1
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• pp.11-16
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• 2008

Infrared (IR) detectors are widely used for such applications as thermoelastic stress analysis, medical diagnostics and temperature measurement. Infrared detectors commonly need to be refrigerated below 80 K, and thus a cooling system should be equipped together with the detector system. The cooling load, which should be removed by the cooling system to maintain the nominal operating temperature of the detector, critically depends on the insulation efficiency of the cryochamber housing the detector. Thermal load of a cryochamber is attributed to the conduction heat transfer through a cold finger, the gases conduction and radiation heat transfer. The thermal loads of an infrared detector cryochamber with a radiation shield are investigated experimentally in present study. Since the effect of radiation heat transfer on thermal loads is significant, radiation shields is installed in the cold finger part to protect heat input through radiation.

• Journal of the Korean Society of Clothing and Textiles
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• v.46 no.5
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• pp.910-926
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• 2022

Suitability for the human body, freedom to move and thermal insulation are important design considerations in military clothing. This study investigates the performance and wearer-satisfaction of the functional inner winter uniform currently used in Korea; it is hoped that our data can inform the development of a future version. Interviews were conducted, in which the participants suggested various improvements. The uniforms were mainly worn for guard duty or as daily attire in cold weather. The participants chose how many layers to wear according to the current situation, rather than sticking to the layering recommended in the manual. Layering choices did not significantly affect combat efficiency but were found to affect wearers' comfort. Wearers' satisfaction was found to depend on the convenience of the clothing, whether it was in the appropriate size, freedom to move and thermal insulation. Also, this study suggests a problem with the current size system, as the analysis of size distribution, across all sizes, the range of current production is insufficient to cover the demand.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.4
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• pp.47-53
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• 2015

The electrical safety and efficiency is the most important thing of the electric vehicle charging system. The prior system is contact charging system that is contacted directly by human. So, it has riskiness such as electric shock in the case of poor insulation or contact problems. To solve these safety issues and the convenience problems, a wireless power transmission system has been developed and is currently in trial operation. However, because high frequency is used in wireless power transmission system instead of commercial frequency, we need to apply protection measures concerning electric shock and equipment protection. Also, it should be accompanied by measuring efficiency for the effective operation of the wireless power transmission system. Therefore, we structured monitoring system in trial operation area of wireless power transmission system and applied decision algorithm for protection of human and equipment and economic operation of it.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.6
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• pp.675-687
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• 2012

Applying an external electric field across air filter media is one of methods to improve the filtration performance. Metal wire meshes have been commonly used as electrodes situated on both sides of a thick filter pad. For a thin filter medium a short circuit, known as the biggest drawback for applying an external electric field to air filter, can occur at the closest point between electrodes. In this study several types of insulated meshes were prepared by coating #50 meshes with a dielectric material, Nylon 66, and the filtration property of air filter was evaluated at the presence of external electric field using those insulated meshes as electrodes and compared with that of filters using bared meshes. The collection efficiency of tested filter was increased from 78% to 95% for singly charged 100 nm particles by application of external electric field. As a result, there was no significant difference in collection efficiency between filters with insulated and bared electrodes. Similar results could be also seen from the tests using polydisperse particles. Finally, through this study, we found that the insulation of mesh electrodes doesn't affect the filtration performance of fibrous air filter under external electric field.

• Journal of the Korean Solar Energy Society
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• v.32 no.2
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• pp.58-63
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• 2012

As the exterior of building has been considered one of th important parts, the use of glass that is suitable to express various appearances gets raised. However, windows have 6~7times lower insulating performance than insulated walls. Lately, highly efficient windows are required as the needs for reduction of energy consumption come to the force. Therefore, Nowadays more people use cooling systems in summer, more the use of Low-E glazing is increasing. Because it is good to block Solar Radiant Energy which can cause much of heat loss while cooling system is working. This study measures U-value of the double Low-E glazing window and commonly used single Low-E glazing window. And then the effect of each window on the efficiency rating has been analyzed applying to the certification system of the building energy efficiency rating which has implemented.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.1
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• pp.1-6
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• 2017

In order to better save energy, many buildings have been constructed with high levels of insulation and airtightness in recent years. Additionally, having high quality indoor air has become more relevant, necessitating a ventilating system. This study is aimed at evaluating the performance of a humidity exchanger through computational fluid dynamics (CFD) analysis of elements for the purpose of providing comfortable indoor air and reduced energy consumption. The simulation was conducted with three different shapes (triangle, rectangular, and curve) of heat exchanger elements, in order to find the most effective element. A follow-up simulation then proved the efficiency of the chosen humidity exchanger, which was selected by analyzing the results of the preceding simulation, comparing study data with measurement data from the Korea Testing Laboratory (KTL). The resulting analysis revealed that the rectangular element showed the lowest level of efficiency in both heating and cooling, while the curved element showed the highest level of efficiency in both heating and cooling.

• Journal of Biosystems Engineering
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• v.8 no.2
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• pp.49-61
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• 1983

U shape multitube heat exchanger was equipped in the flue to recover the exhaust heat from the boiler system. The fluids of the exhaust heat recovery equipment were the flue gas as the hot fluid, and the water as the cold fluid. The flow geometry of the fluids was cross flow - two pass, the hot fluid being mixed and the cold fluid unmixed. The results of the theoretical and the experimental analysis and the economic evaluation are summarized as follows. 1) The heat exchanger effectiveness and the temperature efficiency of the hot fluid were about 35% when the fuel consumption rate was 140 - 150 L/15min. The temperature efficiency for the cold fluid ranged from 3.0% to 4.5%. The insulation efficiency ranged from 85% to 98%, which was better than the KS air preheater insulation efficiency of 90%. 2) The relationship between the fuel consumption rate, F, and the outlet temperature, $T_{h2}$, of the flue gas from the heat exchanger was $T_{h2}$ = 0.927F + 110. In order to prevent the low temperature corrosion from the coagulation of $SO_3$, it is necessary to maintain the fuel consumption rate above 82 L/15min. 3) The ratio of the exhaust heat from the boiler system to the total energy consumption was about 14.5%. With the installation of the exhaust heat recovery equipment, the energy recovery ratio to the exhaust heat was about 25%. Accordingly, about 3.6% of the total fuel consumption was estimated to be saved. 4) Economic analysis indicated that the installation of the exhaust heat recovery equipment was feasible to save the energy, because the capital reocvery period was only 10 months when the fuel consumption rate was 80 L/15min. 4 months when it was 160 L/15min. 5) Based on the theoretical and the experimental analysis, it was estimated to save the energy of about 18 million Won per year, if four heat exchangers are installed in a factory. 6) A further study is recommended to identify the relationship among the flow rate of the exhaust gas, the size of the heat exchanger and the capacity of the air preheater. For a maximum heat recovery from the exhaust gas an automatic control system is required to control the flow rate of the cold fluid depending on the boiler load.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.11
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• pp.25-34
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• 2019

It is important to design windows in a reasonable way considering the performance characteristics of the elements of the window rather than just to increase the thermal energy performance of the window. In this study, the Heat-transfer Coefficient as insulation performance of the windows and together with the grade of the glass's SHGC (Solar Heat Gain Coefficient) were analyzed to relate to the energy efficiency performance of the building by azimuth angle. Based on this basic study, the Heat-transfer Coefficient of windows and the SHGC rating of glass were applied to the unit plan of apartment building, and the Heating and Cooling Demand were analyzed by azimuth angle. Apartment plan types were divided into 2 types of Non-extension and extension of balcony. The designPH analysis data derived from the variant of the Heat-transfer Coefficient and SHGC, were put into PHPP(Passive House Planning Package) to analyze precisely the energy efficiency(Heating and Cooling Demands) of the building by azimuth angle. In addition, assuming the 'ㅁ' shape layout, energy efficiency performance and potential of PV Panel installation also were analyzed by floors and azimuth angle, reflecting the shading effects by surrounding buildings. As the results of the study, the effect of Heat Gain by SHGC was greater than Heat Loss due to the Heat-transfer Coefficient. So it is more effective to increase SHGC to satisfy the same Heating Demand, and increasing SHGC made possible to design windows with low Heat-transfer Coefficient. It was also revealed that the difference in annual Heating and Cooling Demands between the low, mid and high floor households is significantly high. In addition to it, the installation of PV Panel in the form of a shading canopy over the window reduces the Cooling Load while at the same time producing electricity, and also confirmed that absolute thermal energy efficiency could not be maximized without controlling the thermal bridge and ventilation problems as important heat loss factors.

• Asian Journal of Atmospheric Environment
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• v.5 no.4
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• pp.228-236
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• 2011

Since most Green House Gases (GHGs) and air pollutants are generated from the same sources, it will be cost-effective to develop a GHGs reduction plan in combination with simultaneous removal of air pollutants. However, effects on air pollutants reduction according to implementing any GHG abatement plans have been rarely studied. Reflecting simultaneous removal of air pollutants along with the GHGs emission reduction, this study investigated relative cost effectiveness among GHGs reduction action plans in Busan Metropolitan City. We employed the Data Envelopment Analysis (DEA), a methodology that evaluates relative efficiency of decision-making units (DMUs) producing multiple outputs with multiple inputs, for the investigation. Assigning each GHGs reduction action plan to a DMU, implementation cost of each GHGs reduction action plan to an input, and reduction potential of GHGs and air pollutants by each GHGs reduction action plan to an output, we calculated efficiency scores for each GHGs reduction action plan. When the simultaneous removal of air pollutants with the GHGs reduction were considered, green house supply-insulation improvement and intelligent transportation system (ITS) projects had high efficiency scores for cost-positive action plans. For cost-negative action plans, green start network formation and running, and daily car use control program had high efficiency scores. When only the GHGs reduction was considered, project priority orders based on efficiency scores were somewhat different from those when both the removal of air pollutants and GHGs reduction were considered at the same time. The expected action plan priority difference is attributed to great difference of air pollutants reduction potential according to types of energy sources to be reduced.

• KIEAE Journal
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• v.16 no.5
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• pp.39-45
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• 2016

Purpose: The purpose of this study is to analyze the energy saving and cost benefit analysis of the Low-income Energy Efficiency Treatment Program supported by KOREF(Korea Energy Foundation). This program was launched in 2007 and performs building energy retrofit for the low-income and energy poverty houses. Method: Energy simulation and cost benefit analysis were accomplished for the low-income detached houses. The structure of detached house was a lot og block structure, wood frame (single glass) and concrete roof. Baseline model of the low-income detached houses was proposed. Result: Annual heating energy consumptions were decreased by about 3.2% with the window system replacement(Case 1), 9.3% with reinforcement of insulation(Case2), and 12.5% with both(Case 3) compared to those of baseline model. The construction cost will be recouped within 5 years for the Case 1, 3 years for the Case 2, and 3 years for the Case 3. Case 3 was the most cost beneficient construction method in the analyzed cases in this study.