• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.8
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• pp.627-635
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• 2012

This study aims at developing an artificial neural network(ANN)-based predictive and adaptive temperature control method to control the openings at internal and external skins, and heating systems used in a building with double skin envelope. Based on the predicted indoor temperature, the control logic determined opening conditions of air inlets and outlets, and the operation of the heating systems. The optimization process of the initial ANN model was conducted to determine the optimal structure and learning methods followed by the performance tests by the comparison with the actual data measured from the existing double skin envelope. The analysis proved the prediction accuracy and the adaptability of the ANN model in terms of Root Mean Square and Mean Square Errors. The analysis results implied that the proposed ANN-based temperature control logic had potentials to be applied for the temperature control in the double skin envelope buildings.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.4
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• pp.545-551
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• 1997

As the cooling energy requirement in an office building increases due to the increased internal heat gains, the effort to minimize the energy consumption through efficient operation of existing HVAC systems will be beneficial. In this study, one of the energy conserving efforts in an office building, operational strategies of Economizer Cycle Control have been investigated through DOE-2.1E computer simulation. The findings can be summarized : 1) Economizer Cycle Control saves energy throughout the year, 2) Econo-Limit-T must be applied seasonally based on the outside and return air conditions, 3) use of Enthalpy control is more energy efficient than that of Temperature control.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.4
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• pp.36-45
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• 2021

In this study, to improve the indoor thermal environment of the radiant floor heating system, a study was conducted on the temperature change characteristics and energy consumption according to the change of the indoor air set temperature, the supply hot water temperature and the outdoor temperature. As for the control method, the on/off control and the thermal difference proportional control method proposed through previous studies were applied. In addition, in consideration of field applicability, numerical analysis was performed for the case where the indoor air temperature sensor was affected by the wall temperature. As a result, it was found that the temperature difference proportional control method is more effective for thermal comfort and energy saving than on/off control.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.11
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• pp.1084-1091
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• 2004

In automotive air handling system, mixing of air streams by the cooler and the heater affects the comfort of cabin room. In the present study, computer-aided analysis is done to improve the thermal comfort and for the optimal design of automotive HVAC system. The simulation software used was FLUENT, and complicate geometries were created by three dimensional CAD. Air flow volume, fir distribution rate and temperature controllability and temperature differences between upper and lower discharge air are analyzed through numerical simulation at vent, floor and defrost mode. Also, velocity vector of sirocco fan is investigated through the scroll housing. The velocity vector magnitude is larger at lower region of fan than that at any other regions. Recirculation and disturbance of air is relatively high near the cut-off edge in the scroll housing. By using the results of this study, the time for prototype production can be reduced and timely decisions can be made to determine initial design directions.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.243-251
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• 2015

This study aimed to determine the effects of root zone cooling using air duct on air temperature distribution and root zone and leaf temperatures of sweet pepper (Capsicum annum L. 'Veyron') grown on coir substrate hydroponic system in a greenhouse. When the air duct was laid at the passage adjacent the slab, the direction of air blowing was upstream at $45^{\circ}$. The cooling temperature was set at $20^{\circ}C$ for day and $18^{\circ}C$ for night. For cooing timing treatments, the cooling air was applied at all day (All-day), only night time (5 p.m. to 1 a.m.; Night), or no cooling (Control). The air temperature inside the greenhouse at a height of 40 and 80cm above the floor, and substrate and leaf temperatures, fruit characteristics, and fruit ratio were measured. Under the All-day treatment, the air temperature was decreased about $4.4{\sim}5.1^{\circ}C$ at the height of 40cm and $2.1{\sim}3.1^{\circ}C$ at the height of 80cm. Under the Night treatment, the air temperature was decreased about $3.4{\sim}3.8^{\circ}C$ at the height of 40cm and $2.2{\sim}2.7^{\circ}C$ at the height of 80cm. The daily average temperature in the substrate was in the order of the Control ($27.7^{\circ}C$) > Night ($24.1^{\circ}C$) > All-day ($22.8^{\circ}C$) treatment. Cooling the passage with either upstream blowing at $45^{\circ}$ or horizontal blowing at $180^{\circ}$ was effective in lowering the air temperature at a height of 50cm; however, no difference at a height of 100cm. Cooling the passage with perpendicular direction at $90^{\circ}$ was effective in lowering the air temperature at the height between 100 and 200cm above the floor; however, no effect on the temperature at the height of 50cm. A greater decrease in leaf temperature was found at 7 p.m. than that at 9. a.m. under both All-day and Night treatments. Fresh weight partitioning of fruit was in the order of the All-day (48.6%) > Night (45.6%) > Control (24.4%) treatment. A higher fruit production was observed under the All-day treatment, in which the accumulated average temperature was the lowest, and it may have been led to a higher proportion of photosynthate distributed to fruit than other treatments.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.5
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• pp.436-443
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• 2005

Experimental study was performed to understand the operation of an on-site showcase working in a super discount store. Inlet and outlet temperatures of evaporator, condenser, expansion valve and compressor were measured for both air and refrigerant sides. Electric power consumption of compressors, defrosting heaters, cooling water pumps and etc. were measured. The operating characteristics of the showcase system under various working conditions were analyzed and discussed. During the defrosting process, the air temperature inside the showcase increased to $15^{\circ}C$, which gave harmful effect to the frozen food. The collected data will serve as valuable information for diagnosing and improving the performance of showcases.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.6
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• pp.121-125
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• 2013

This study was carried out to provide a valuable reference which could reduce heating loss of air-inflated double PO film. Therefore, this study was aimed to choose the best air space thickness and injected air temperature. The characteristics of heat transmission variation at experimental materials were measured and analysed in the laboratory. The experiment was conducted of two layers of PO film, each 0.15 mm tick, sandwiching 110, 175, 225 mm of inflated air with 1 m sides. Environmental control lab was constantly controlled with $-10^{\circ}C$ and experiment chamber was constantly changed with 0, 5, 10, $15^{\circ}C$. The analysis of heat transfer showed that heat transmission does not have a direct correlation with Air Space thickness and injected air temperature. But when inside and outside temperature difference of chamber was great, supply of outside air to Air Space had an advantage at reduction of heating load. It was required to examine accurate analysis at a real greenhouse.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.2
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• pp.39-48
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• 2000

The purpose of this study is to investigate the factors affecting temperature of urban parks to grasp the relationship between the land coverage in open space as well as the forest condition and decreasing city temperature by difference of purposed are. Futhermore, this research interpreted the relationship between wind direction, air temperature, the land coverage of the green space, the number of tree, green volume, height of tree and the mitigation of city temperature with the revolution analysis. The result of this study is that cool air in open space move leeward and decreasing city temperature is influenced by the difference of the land coverage in open space. Specifically, in order of the arbo $r_{-a}$rbor in the forest zone, the increase of the number of trees was related with temperature surrounding significantly. This study found that the use possibility of the green volume was recognized as the index of the green volume relative to air temperature surrounding. Green space of the city control area is more effective decreasing temperature than that of housing zone.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.322-327
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• 2007

Dedicated outdoor air-conditioning(DOA) system that utilizes pre-cooling and desiccant dehumidification can be superior to conventional cooling and reheating system with respect to energy consumption and indoor thermal comfort. In this work, simulation has been conducted to study various factors that affect the performance of DOA. Dynamic simulation shows the transient variation of temperature and humidity as the on/off control logic is imposed. Exit humidity of process air and flow rate are varied to study the effect on exit temperature of process air, dehumidification quantity, required regeneration temperature and exit humidity of regeneration air. For an outdoor air condition of $28.5^{\circ}C$ temperature, 16 g/kg humidity ratio and 2000 cmh flow rate, the dehumidification efficiency is increased by 4.6% as the flow rate is doubled.

• Journal of Ocean Engineering and Technology
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• v.14 no.2
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• pp.60-64
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• 2000

An experimental study was performed to investigate the optimal ejector and operating condition of vessel incinerator. Exhaust gas temperature and secondary air which makes vacuum pressure at ejector throat regions were considered as an important factor. According to the measurement of pressure temperature and nitrogen oxides between non combustion and combustion we found the stream and exhaust gas characteristics of incinerator. This results can give us the exhaust gas temperature control system air pollutant reduction method and the optimum ejector design.