• 한국생산제조학회지
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• 제24권2호
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• pp.251-255
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• 2015

Thermal deformation, such as bending and twisting, occurs among the polymer parts of air-conditioner indoor units because of repetitive temperature change during heating operation. In this study, a numerical method employing finite-element analysis to efficiently simulate the thermal deformation of an assembly is proposed. Firstly, the displacement of an actual assembly produced by thermal deformation was measured using a 3D optical measurement system. The measurement results indicated a general downward sag of the assembly, and the maximum displacement value was approximately 1 mm. The temperature distribution was measured using a thermographic camera, and the results were used as initial-temperature boundary conditions to perform temperature-displacement analysis. The simulation results agreed well with the measured data. To reduce the thermal deformation, the stiffness increased 100%. As the results, the maximum displacement decreased by approximately 5.4% and the twisting deformation of the holder improved significantly.

• International Journal of Costume and Fashion
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• 제9권1호
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• pp.34-43
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• 2009

This study compared the thermal comfort of indoor clothing from Tencel material that is getting higher in demand due to being eco-friendly with superior wettability, with that from Polyester material that despite being most widely used for indoor clothing, rapidly discharges body sweat due to low wettability. The experiments were performed in the two manners, objective evaluation under the conditions of an artificial climate chamber and subjective evaluation of wearing the given clothes at home followed by filling in the questionnaire. Subjects were 8 healthy elderly women in their 60's who spend majority of their time at home rather than in social activities, and comparison was made on skin temperature and humidity inside clothing at exercise and relaxation states under early summer environment. Based on these results, wearing Tencel material clothing maintained cooler temperatures under warm environment rather than when wearing Polyester material clothing, thus enabling activities under more comfortable state. Regarding humidity inside clothing, parts with twofold clothing did not show difference between Tencel and Polyester, but the onefold arm showed lower when wearing Tencel. With this results, Tencel is regarded as more comfortable and nicer than Polyester.

• 한국지열·수열에너지학회논문집
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• 제12권4호
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• pp.21-26
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• 2016

In this study, the control strategies of indoor air temperature in floor radiant heating system were researched by computer simulation. The temperature difference based time control method using the difference of indoor set temperature and indoor temperature is compared with the existing On-Off control one for heating control performances. As a result, the temperature difference based time control method shows better thermal environmental characteristics in case of selected operational conditions in comparison with existing control one.

• 설비공학논문집
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• 제15권6호
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• pp.524-532
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• 2003

In this paper, a personal air-conditioning system considering the human thermal adaptability is analyzed. Although the conventional personal air-conditioner was proofed to be satisfactory in providing for the thermal comfort, it is being questioned on the term of its energy efficiency. Therefore, it is important and urgent to develop new types of personal air-conditioning system with sustainable control strategy that can ensure energy saving and thermal comfort simultaneously. In this study, we first examined the problems of the conventional personal air-conditioning system with field interview and laboratory experiment in terms of usage, management and thermal comfort, and proposed the energy-saving personal air-conditioning system considering the human thermal adaptation. Then a laboratory experiment was performed to analyze the characteristics of the human thermal comfort under severe indoor thermal conditions, which were controlled using a new personal air-conditioning unit designed according to the proposal. The results help to illustrate the alleviation effect of the new personal air-conditioning system, and indicate that the thermal alleviation time is useful to maintain the thermal comfort with efficient usage of energy.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.317-322
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• 2008

The objectives of this paper are to study the effects of thermal and geometric conditions on the performance of indoor heat exchanger with R410A for Gas Engine Driven Heat Pump (GHP) application and to find optimum design conditions of indoor heat exchanger by parametric analysis for the key parameters. In the air side, moisture out of the humid air condenses on the fin surface while the refrigerant (R410A) boils inside the smooth tube. Therefore this study uses Log Mean Enthalpy Difference (LMHD) method to analyze the heat transfer from the humid air to the refrigerant of R410A. The results show that fin pitch and longitudinal pitch have significant effect on the heat exchanger preformance. This study will provide the guideline for optimum design of indoor heat exchanger with R410A for GHP application.

• International Journal of Air-Conditioning and Refrigeration
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• 제17권4호
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• pp.129-134
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• 2009

The objectives of this paper are to study the effects of thermal and geometric conditions on the performance of indoor heat exchangers with R-410A for Gas Engine Driven Heat Pump (GHP) application and to find the optimum design conditions of indoor heat exchangers by parametric analysis for the key parameters. The key parameters are number of tube row, number of tube pipe, fin pitch and transverse tube pitch. In the air side, moisture out of the humid air condenses on the fin surface while the refrigerant (R-410A) boils inside the smooth tube. Therefore this study uses Log Mean Enthalpy Difference (LMHD) method to analyze the heat transfer from the humid air to the refrigerant. This study determines the heat exchanger size, air side/refrigerant side pressure drop and overall heat transfer coefficient. Optimum design conditions for the key parameters are also determined by the parametric analysis. The results show that number of rows and pipes, fin pitch have significant effect on the heat exchanger size. It is also found that the tube length of the louver fin is $17{\sim}30%$ shorter than that of the plate fin.

• 설비공학논문집
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• 제18권7호
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• pp.535-540
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• 2006

This study was performed In evaluate sleep efficiencies and conditions for comfortable sleep based on the analysis of Physiological signals under variations in thermal conditions. Five female subjects who have similar life cycle and sleep patterns were participated for the sleep experiment. It was checked whether they had a good sleep before the night of experiment. EEGs were obtained from C3-A2 and C4-A1 electrode sites and EOGs were acquired from LOC (left outer canthus) and ROC (right outer canthus) for REM sleep detection. Sleep stages were classified, then TST (total sleep time), SWS (slow wave sleep) latency and SWS/TST were calculated for the evaluation of sleep efficiencies on thermal conditions. TST was defined as an amount of time from sleep stage 1 to wakeup. SWS latency was from light off time to sleep stage 3 and percentage of SWS over TST was calculated for the evaluation of sleep quality and comfort sleep under thermal conditions. As result, the condition which raise a room temperature provided comfortable sleep.

• 설비공학논문집
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• 제16권10호
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• pp.960-968
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• 2004

One of the most important functions of a building is to provide thermally comfortable indoor environmental conditions for the occupants. Therefore, a great deal of energy is consumed for heating and cooling to satisfy those thermal requirements. In order to provide thermal comfort with minimum heating and cooling energy consumption, optimal design of building affecting indoor climate is required. This study used the TRNSYS for modeling and simulation of the energy flows of residential building types, and examined the energy efficient measures to reduce the thermal loads. The residential building types are classified into the detached house, apartment house and high-rise residential complex. The results of the simulation show that the heating energy consumption in the detached house is especially high, whereas the cooling load is an important determinant in the apartment house and high-rise residential complex. The measures examined are the insulation thickness, various types of glazing, infiltration, natural and controlled ventilation, solar shading, orientation and etc. Comparative evaluations and sensitivity analyses revealed the effects of these variables and identified their energy efficient building design strategies.

• KIEAE Journal
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• 제16권3호
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• pp.71-76
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• 2016

Purpose: This study aimed at improving the indoor environment of the office building by measuring the indoor environment and conducting a survey. Method: The measurement was conducted from January 13 to March 16 in 2012, targeting 44 sites in same office building located in Seoul, South Korea. The lists of measurement such as dry-blub temperature, relative humidity, formaldehyde (HCHO), asbestos, carbon monoxide (CO), carbon dioxide (CO2), volatile organic compounds (VOCs) and particle pollution (PM10) were measured. In addition, illuminance which belongs to light environment and noise in sound[acoustical] environment were measured respectively. Result: The buildings showed overall pleasant conditions. In terms of the thermal, air, sound, and visual environment, each measurements were satisfied with the requirements in standard, within pleasant ranges, except several sites. However, the survey results were revealed that the office workers were mostly dissatisfied with their indoor environment. Given that the measured values were mostly within standards, the results of survey might have resulted from a compensation mentality biased toward the subjects in psychological terms.

• 한국환경보건학회지
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• 제41권6호
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• pp.389-396
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• 2015

Objectives: A hospital is a complex building that serves many different purposes. It has a major impact on patient's well-being as well as on the work efficiency of the hospital staff. Thermal comfort is one of the major factors in indoor comfort. The purpose of this study was to determine thermal comfort in various locations in a hospital. Methods: Various indoor environmental conditions in a general hospital were measured in February 2014. The predicted mean vote (PMV) and carbon dioxide ($CO_2$) concentration were measured simultaneously in the lobby, office, restaurant, and ward. Results: The ward was the most thermally comfortable location (PMV=0.44) and the lobby was the most uncomfortable (PMV = -1.39). However, the $CO_2$ concentration was the highest in the ward (896 ppm) and the lowest in the lobby (572 ppm). The average PMV value was the most comfortable in the ward and the lowest in the lobby. In contrast, for concentration of carbon dioxide, the highest average was in the ward and the lowest in the lobby. Due to air conditioner operation, during operating hours the PMV showed values close to 0 compared to the non-operating time. Correlation between PMV and $CO_2$ differed by location. Conclusion: The PMV and concentration of carbon dioxide of the hospital lobby, office, restaurant and ward varied. The relationship between PMV and carbon dioxide differed by location. Consideration of how to apply PMV and carbon dioxide is needed when evaluating indoor comfort.