• 한국산업융합학회 논문집
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• 제27권3호
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• pp.655-663
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• 2024

In order to meet the technological demand for indoor heating systems that ensure winter thermal comfort during the transition from internal combustion engines to electrification, a localized proximity heating module using surface heating elements was developed. The operational performance of heating module was tested in the low temperature chamber. The experiment conditions were varied by changing the chamber temperature (-10, 0℃), the air flow rate (6.2, 6.0, 4.2m³/h), the heater power (100, 80, 60, 40W). Thermal comfort model was confirmed using the CBE Thermal Comfort Tool applying ASHRAE standard 55. Under -10℃ condition, thermal comfort was satisfied at 23.4, 23.2℃ at power of 100W and air flow rate 6.0, 4.6m³/h. Under 0℃ condition, at power of 80W, air flow rate 6.2, 6.0m³/h, and at power of 60W, air flow rate 4.6m³/h showed results of 25.7, 26.1, 23.0℃, respectively, satisfying thermal comfort. This study analyzed the operating performance of the local proximity heating module in the low temperature chamber and applied thermal comfort model to prove applicability of local proximity heating module using surface heating elements and how to utilize the thermal comfort model.

• 한국환경과학회지
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• 제14권2호
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• pp.215-220
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• 2005

Thermal neutrality is not enough to achieve thermal comfort. The temperature level can be the optimal, and still people may complain. This situation is often explained by the problem of local discomfort. Local discomfort can be caused by radiant asymmetry, local air velocities, too warm and too cold floor temperature and vertical temperature difference. This temperature difference may generate thermal discomfort due to different thermal sensation in different body parts. Therefore, thermal comfort can not be correctly evaluated without considering these differences. This study investigates thermal discomfort sensations of different body parts and its effect on overall thermal sensation and comfort in air-heating room. Experimental results of evaluating thermal discomfort at different body parts in an air-heating room showed that thermal sensation on the shoulder was significantly related to the overall thermal sensation and discomfort. Although it is known that cool-head, warm-foot condition is good for comfort living, cool temperature around the head generated discomfort.

• 한국지역사회생활과학회지
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• 제15권2호
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• pp.55-64
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• 2004

The purpose of this study was to examine the differences in skin temperature and thermal comfort of participants in a $19^\circ{C}$ room (the recommended room temperature in the winter) depending on age, sex and clothing weight. Subjects were divided into four groups (6 young males, 5 young females, 6 old males, 6 old females) and experimental trials consisted of three conditions: wearing underwear in a $19^\circ{C}$ room (19CUW), without underwear in a $19^\circ{C}$ room (19C), and without underwear in a $24^\circ{C}$ room (24C). The results indicated the following: 1) There were no significant differences in mean skin temperature based on age or sex, and the mean skin temperatures of the four groups were in the range of 32.4∼$34.0^\circ{C}$. 2) In the 19C condition, the skin temperatures of the hands and feet of old females were higher than those of the other three groups. 3) In terms of perceived thermal comfort, young females showed a tendency to feel the most uncomfortable. Both old and young groups agreed that the 24C condition was the most comfortable. 4) Relational coefficients between thermal comfort and skin temperatures were higher in the young group than in the old group. Furthermore, the perceived thermal comfort had a stronger relationship with mean skin temperatures than with local skin temperatures. 5) The mean skin temperatures of subjects who indicated they were 'comfortable' were in the range of 31∼$36^\circ{C}$ regardless of age or sex.

• 한국가시화정보학회지
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• 제14권1호
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• pp.19-26
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• 2016

Modern people spend much time at indoor space. So, People want to make better indoor air condition. But the facade of building is made of glass to be seen urbanely, the effect of solar radiation makes indoor environment worse. This study designs an open space affected by solar radiation with 4-way cassette air-conditioner. Using numerical simulation, this paper investigates thermal comfort and ventilation performance with discharge angles $30^{\circ}$ and $45^{\circ}$. To study thermal comfort, this paper studies distribution of velocity, temperature and effective draft temperature. Also, this paper introduces concept of air age to study ventilation performance. The flow influenced by solar radiation determines thermal comfort and ventilation performance in room space. This study shows that discharge angle of 45 degree has better thermal comfort and ventilation performance than that of 30 degree.

• 한국가시화정보학회지
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• 제21권2호
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• pp.72-82
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• 2023

Effective thermal management in a battery electric vehicle (BEV) is crucial for reducing energy consumption and maximizing driving range in cold climates. Consequently, original equipment manufacturers are actively investing in the development of local heating systems. Visualizing occupant thermal behaviors or comfort can readily provide valuable insights that would substantially impact the design and control strategies of such microclimate systems. This study uses MATLAB for three-dimensional visualization of human thermal psychology. The developed program enables qualitative assessment of occupant comfort in BEVs.

• 설비공학논문집
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• 제15권4호
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• pp.318-328
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• 2003

Numerical simulation using computational fluid dynamics (CFD) is performed to calculate the velocities and temperature profiles of air in adjacent to a worker within the individual local air conditioning system. The calculation domain is the space of ㄴ between walls and a worker in the climate room. The fresh air is supplied from the three different inlets located on the right, left and center wall in the climate room. In this study, the calculated data of velocities and temperature profiles of air in the nearest the skin of a worker are used to calculate the PMV (Predicted Mean Vote) for evaluation of thermal comfort of a worker in the local air conditioning system. Because the data of veto-cities temperature profiles of air in adjacent to a worker and the PMV of a worker are the design parameters of the local air conditioning system. The results of calculation show that the fresh air velocity and injection position are closely related to the PMV value. In individual air condition system of ㄴ, the appropriate PMV are obtained when the fresh air velocity and position are 1.0 m/s, throat of a worker and are 1.5 m/s, head of a worker, respectively. The method of numerical calculation is effective to obtain the optimum velocity and position of the fresh air for optimum the PMV and energy saving in individual local air conditioning system.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.115-123
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• 2010

Cool-down performance after soaking is important because it affects passenger's thermal comfort. The cooling capacity of HVAC system determines initial cool down performance in most cases, the performance is also affected by location, and shape of panel vent, indoor seat arrangement. Therefore, optimal indoor designs are required in developing a new car. In this paper, initial cool down performance is predicted by CFD(computational fluid dynamics) analysis. Experimental time-averaging temperature data are used as inlet boundary condition. For more reliable analysis, real vehicle model and human FE model are used in grid generation procedure. Thermal and aerodynamic characteristics on re-circulation cool vent mode are investigated using CFX 12.0. Thermal comfort represented by PMV(predicted mean vote) is evaluated using acquired numerical data. Temperature and velocity fields show that flow in passenger's compartment after soaking is considerably unstable at the view point of thermodynamics. Volume-averaged temperature is decreased exponentially during overall cool down process. However, temperature monitored at different 16 spots in CFX-Solver shows local variation in head, chest, knee, foot. The cooling speed at the head and chest nearby panel vent are relatively faster than at the knee and foot. Horizontal temperature contour shows asymmetric distribution because of the location of exhaust vent. By evaluating the passenger's thermal comfort, slowest cooling region is found at the driver's seat.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.383-388
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• 2008

We are now developing a CFD program, AIRVIEW, with several numerical models and the SIMPLER solving method for constructing flow field and thermal comfort. This study is carried out for evaluating an accuracy of AIRVIEW. Comparisons of accuracy are carried out using Phoenics Version 3.4. In this study, we compare the turbulent kinetic energy distribution and local turbulent Re number obtained with Phoenics with those results simulated by AIRVIEW for three kinds of duct. It is observed from comparison of results that the turbulent kinetic energy values are significant due to the large velocity gradients in the region of flow. Numerical results for turbulent kinetic energy distribution and local turbulent Re number are that a good degree of agreement is found.

• 한국주거학회논문집
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• 제7권2호
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• pp.121-129
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• 1996

This study was to estimate how about various effects on the body thermal sensation as air velocity. clo. mean radiant temperature and resultant temperature are varied. The indoor thermal environment elements are measured under the five different of air velocity. Using the above considerations. the following results are obtained. ▶ The states, the air velocity under 0.5 m/s and 0.63 to 0.9 clo. were shown that the comfort zone of mean radiant temperature by 21.2~24.7C, the neutral point by 22.8C, the resultant temperature by 20.7-24.4C and the neutral point by 22.6C. ▶ On equal condition, the draft was occurred at a given air-velocity under 0.5m.s. It was also appeared the floor panel heating system affecting the body thermal sensation by the subject’s below-chest parts and the local discomfort by sensations on the feet and the knees.

• 한국지역사회생활과학회지
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• 제27권4호
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• pp.795-801
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• 2016

This study was conducted to suggest the best union fabric to combine with cellulose fiber for summer and in-between seasons. Four types of union fabric, viz. silk/flax, silk/cotton, rayon/flax and rayon/cotton, were used as sample fabrics after weaving them in a local textile factory. The air permeability, moisture regain, water absorption, water vapor permeability and thermal insulation of the samples were tested. The results are as follows. The rayon/flax union fabric is the most suitable for summer clothes due to its having the best comfort property of air and water vapor permeability, and moisture and water absorption. For in-between seasons, it is recommended to use the silk/cotton union fabric because of its good thermal insulation properties.