• 설비공학논문집
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• 제12권5호
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• pp.476-485
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• 2000

This study numerically investigates thermal comfort in a space cooled by the floor-supply air conditioning system, in which three different supply-return locations, one floor supply-ceiling return and two floor supply-floor returns, are treated. A complementary experiment is peformed to validate the present numerical analysis, and the prediction agrees favorably with the measured data. In the numerical procedure, a simplified model mimicking the inlet flow through the diffuser is developed for efficient simulations. The calculated results show that the ceiling return type is far better in thermal comfort than the floor return ones within the extent of this study, which seems to be caused by effective vertical penetration of the supply air against natural convection. It is also revealed that the arrangement of port locations in the floor supply-floor return system has insignificant effect on the cooling performance. For selecting a proper system, other characteristics including the heating performance should be accounted for simultaneously with the present estimation.

• 설비공학논문집
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• 제12권9호
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• pp.810-816
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• 2000

Thermal comfort plays an important role in modern office buildings. Four major factors affecting thermal comfort are air temperature, velocity, humidity and radiation temperature. Distribution of these thermal factors in indoor space depends largely on the air flow which is related to the method of supplying and extracting air. In this study, an experimental analysis on indoor thermal comfort is conducted to study the difference between a ceiling supply cooling system and a floor supply one. The two cooling systems are applied to an office space during summer season and the distributions of temperature, velocity, radiation temperature and PMV are measured. Results show that the floor supply cooling system is superior in terms of thermal comfort and energy saving. Studies need to be done, however, to reduce the vertical temperature difference of a floor supply air conditioning system.

• International Journal of Air-Conditioning and Refrigeration
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• 제9권4호
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• pp.37-46
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• 2001

This study numerically investigates thermal comfort of a space cooled by a floor-supply air-conditioning system, in which three different combinations of supply and return locations, one floor-supply/ceiling-return and two floor-supply/floor-return, are treated. A complementary experiment is performed to validate the present numerical analysis, and the prediction agrees favorably with the measured data. In the numerical procedure, a simplified model mimicking the inlet flow through a diffuser is developed for efficient simulations. The calculated results show that the ceiling-return type is far better in terms of thermal comfort than the floor-return ones within the extent of this study, which seems to be caused by effective vertical penetration of the supply air against natural convection. It is also revealed that the arrangement of port locations in the floor-supply/floor-return system has insignificant effect on the cooling performance. For selecting a proper system, other characteristics including the heating performance should be accounted for simultaneously with the present considerations.

• International Journal of Air-Conditioning and Refrigeration
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• 제11권2호
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• pp.67-72
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• 2003

A partition integrated air supply system can provide highly personalized environmental control. The supply air is brought up through raised floors and supplied to outlets located on the partition panels. The purpose of this paper is to find out the best design of outlets for optimal occupant comfort within a personal task area. Real scale experiments were conducted to allow for comparisons of outlet designs within a personal task area. Experimental results indicate that the location of an outlet is the most critical factor in improving the efficiency of supply air distribution of a personal task area. Thermal characteristic comparisons were made between the under-floor and the partition supply systems. Experimental results suggest that the partition supply system is more efficient than the under-floor supply system in terms of cooling. Such a system allows occupants to personally control their immediate environment, resulting in higher productivity.

• 설비공학논문집
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• 제11권5호
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• pp.669-683
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• 1999

Heat dissipation in the domestic switching room has been gradually increased. Therefore, numerical study on the cooling characteristics of the telecommunication system in a switching room for three kinds of the air supply and return flow system was investigated to develop effective flow system. As a result, the cooling performance of the under floor air supply and overhead return flow system was the best.

• 설비공학논문집
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• 제11권1호
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• pp.117-124
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• 1999

In this study, three different supply diffuser types(desktop, floor and ceiling) are compared in view of their ability to distribute supply air to the workstation breathing zone. The measurements on the age of air and the air change effectiveness using the tracer gas method are carried out to analyze the ventilation performance for provision of fresh air between the diffusers. The desktop diffuser type could deliver air directly to the occupants breathing zone with a high degree of effectiveness. The measured local air change effectiveness of the desktop diffuser in the breathing zone was usually 1.13 to 1.23 times greater than that of ceiling and floor diffusers. When the minimum outside air change rate as specified using ASHRAE Standard 62R is supplied with a desktop diffuser type, the volume of outside air can be reduced 13 to 23%, resulting in a commensurate in ventilation energy use.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.866-871
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• 2006

Recently according to the fashion of well-being, the case study of under floor heating system type for residential space is increasing. Specially double slab floor system can make several roles as reducing the acoustic noises and also supplying fresh air through the gap. So in present study floor heating performance was examined with various location of the space in the case of floor supply air and ceiling supply air. In both cases return air went out through ceiling opening. As one of the result is that when using the heat pipe type floor heating system the temperature difference between supply and return water was $15.2^{\circ}C$, but in case of commercial type floor heating system the temperature difference was $5.3^{\circ}C$ when the supply water temperature was $50^{\circ}C$.

• 설비공학논문집
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• 제11권3호
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• pp.301-312
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• 1999

Experiments were carried out to evaluate performance of the cold air distribution systems with an ice storage tank in test room. Cold air distribution systems provide primary air for comfort conditioning or process cooling at coil discharge temperatures$4^{\circ}C$ to$11^{\circ}C$. The application of a cold air distribution system allows for the downsizing of air distribution equipment and central plant equipment when ice storage tank is used. The benefit of a cold air distribution system include a decrease in the floor-to-floor height, increase floor space, reduced building capital costs, reduced energy use and demand. The use of cold air distribution can result in the most cost effective system and is currently being implemented world wise as the new standard in air conditioning systems. In this study, the cold air distribution system is compared with the general ice storage system. Under the same cooling load conditions, experimental results show that the supply air volume of cold air distribution system decrease 38%, and decrease 45% flow rate of brine for the general ice storage system.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제25권4호
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• pp.27-35
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• 2019

Purpose: As the improvement in quality of medical environment and the spatial consideration for the prevention of infection in the hospital have become increasingly important in the recent years, specific and practical planning for air conditioning room's area has become a major issue accordingly. However, the air conditioning room tends to be discussed focusing on technical factors such as air conditioning systems that are irrelevant to building plans, while discussions of most departments related to the medical functions have actively taken placed. Therefore, this study aims to investigate the factors influencing the planning for the air conditioning room area, and through subsequent analysis of the area of the air conditioning room, to propose a way to improve effective planning for the air conditioning room area. Methods: This study examines the case hospitals that fall into two types: each floor supply system and concentrated supply system, and compares and analyzes the air conditioning room area-related factors and the characteristics of changes in the interior of air conditioning room before and after remodeling through air conditioning floor plan of those case hospitals. Results: The air conditioning room can be classified into the net area of the functional space such as duct passages, and the public area such as aisle space, and of those the public area is an important factor in calculating the area of the air conditioning room. The public area of the air-conditioning room should not be planned considering only the spaces for mobile passage or maintenance activities, but should be planned taking into account internal changes such as expansion and replacement of equipment in the future from the beginning. Implications: When planning a medical facility, it is used as basic data for the planning of the air conditioning room area, which is a significant fixed factor in the initial setting.

• International Journal of Air-Conditioning and Refrigeration
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• 제7권
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• pp.91-100
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• 1999

This paper investigates ventilation characteristics of an environmental chamber simulating an under-floor air conditioning system for isothermal and cooling supply air conditions. The tracer gas sulfur-hexafluoride (SF$F_6$) was injected into a supply duct using step-up and step-down methods. Local mean and room mean ages were calculated from the concentrations measured at internal points and at the exhaust duct. The air change efficiency of the chamber has been found to be greater in cooling conditions than in isothermal conditions. Also the room air change efficiency is not significantly affected but slightly improved by the presence of a supply diffuser.