• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.2
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• pp.161-168
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• 2011

The heating, ventilating, air conditioning (HVAC) system is a very important part of an automotive vehicle: it controls the microclimate inside the passenger's compartment and removes the frost or mist that is produced in cold/rainy weather. In this study, the numerical analysis of the defrost duct in an HVAC system and the de-icing pattern is carried out using commercial CFX-code. The mass flow distribution and flow structure at the outlet of the defrost duct satisfied the duct design specification. For analyzing the de-icing pattern, additional grid generation of solid domain of ice and glass is pre-defined for conductive heat transfer. The flow structure near the windshield, streakline, and temperature fields clearly indicate that the de-icing capacity of the given defrost duct configuration is excellent and that it can be operated in a stable manner. In this paper, the unsteady changes in temperature, water volume fraction, and static enthalpy at four monitoring points are discussed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.3
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• pp.253-262
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• 2007

Although the importance of good conservation of historical sites including ancient royal tombs is well aware, still not much attention has been paid for facilities to realize it. There are numerous ancient royal tombs spread in Korean peninsula which are opened and some of them are selectively on display for public access. However, the conservation measures of these sites have not been seriously investigated. Even the level of understanding of the underground environment of tombs is not satisfactory. In the present study, we focus on the dehumidification loads to maintain appropriate conservation conditions in terms of temperature and humidity. Two experimental tombs different in size were built in KNU (Kongju National University) campus with the dimensions ($L{\times}W{\times}H$) of $1.0m{\times}2.8m{\times}1.0m\;and\;1.3m{\times}3.0m{\time}1.2m$, respectively, HVAC systems are installed to maintain a suitable condition for conservation, i.e., $22{\pm}2^{\circ}C$ in temperature and $55{\pm}5%$ in relative humidity. The condensed water are measured to estimate the dehumidification loads while the temperature and the humidity inside the tombs were maintained within the specified range.

• Journal of Practical Engineering Education
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• v.9 no.2
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• pp.149-153
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• 2017

Inside the vehicle, temperature and humidity are suddenly changed. Accordingly, HVAC System's temperature control is very complicated. But, clarifying the relationship between temperature and humidity can reduce the control parameters. Therefore, this paper describes the relationship between temperature and humidity in the vehicle and presents a problem solving method in terms of control technologyThe vehicle sensor monitors the factors required for vehicle control and plays a role in enabling optimal control from the obtained information. Of these sensors, the driving environment of the driver is determined by the temperature and humidity inside the vehicle, and the characteristics of the vehicle suddenly change rapidly. Accordingly, HVAC System's temperature control is very complicated. But, clarifying the relationship between temperature and humidity can reduce the control parameters. Therefore, this paper describes the relationship between the temperature and humidity in the vehicle, and presents a method for controlling the temperature and humidity in the vehicle as an example.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.E
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• pp.45-54
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• 1995

Indoor air quality models are useful to predict indoor air pollutant concentrations as a function of several indoor factors. Indoor air quality model was developed to evaluate the pollutant removal efficiency of variable-air-volume/bypass filtration system (VAV/BPFS) compared with the conventional variable-air-volume (VAV) system. This model provides relative pollutant removal effectiveness of VAV/BPFS by concentration ratio between the conventional VAV system and VAV/BPFS. The predictions agree closely, from 5 to 10 percent, with the measured values for each energy load. As a results, we recommend the VAV/BPFS is a promising alternative to conventional VAV system because it is capable of reducing indoor air pollutant concentration and maintaining good indoor air quality.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.241-244
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• 2008

Recently, The high Air-Tightness and high heat insulation for building construction cause a ventilation air volume deficiency. Also, Worldwide high energy price is strongly urging to economize the air conditioning energy. Therefore Heat Recovery Ventilation is used for the satisfaction of ventilation air volume and building energy saving. Accordingly, this study dose the heat exchanger performance evaluation and economic efficiency evaluation of Heat Recovery Ventilation. And, we wish to make a basic study about HRV System application of HVAC System and Multi System Air-conditioning.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1288-1292
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• 2007

Because the indoor spaces of the passenger cabin is generally airtight to secure the safety of passengers and enhance the efficiency of the cabin air conditioning performances, the contamination pattern of them are largely similar to that of general indoor spaces. Therefore, continuous supply of outdoor air is required to keep the amenity of indoor space. Heating, ventilation, and air-conditioning (HVAC) system is composed of air cleaning filter, heater and air conditioned, blower and ducts. To achieve the clean indoor environment, an integrated control of each HVAC equipment are required. In this study, we developed the air cleaning system to enhance the amenity of the railroad passenger cabin.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.519-524
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• 2011

The aim of this study is to develop an automated program for noise prediction in shipboard compartments, for this purpose of calculating noise levels accurately and quickly. The program calculates sound power level at HVAC components based on the empirical method suggested by NEBB and utilizing the manufacturer's test data. The program developed uses the GUI functions to help in efficient modeling and calculation. To verify the reliability of developed program, the predicted data was compared with the measured data in shipboard compartments. As a result, the average difference between predicted and measured data is ${\pm}3dB$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.5
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• pp.346-351
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• 2003

This paper aims at suggesting design guidelines for a perimeter-less HVAC system that contributes energy savings. Perimeter-less HVAC system is one that relieves difficulties fuck as handling mixing loss, uneven radiative environment, and maintenance and repair. It prevents heat load gained through window and outdoor wall without modifying a previously equipped building skin system. In this paper, we performed several kinds of CFD (computational fluid dynamics) cases through numerical simulation to obtain an optimized perimeter-less design, and then we conducted a large-scale model experiment to see how the push-pull air flow would handle indoor heat to obtain an optimized perimeter-less design.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2989-2994
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• 2008

The shopping center in underground passage for efficient space utilization is increased in urban area. This study describes operation characteristics of HVAC systems with ventilation and individual heating and cooling unit for shopping center in underground passage. In order to compare energy saving, thermal environment and installation space, etc., an integrated simulator with heat production and distribution system was designed and constructed. Energy delivery efficiency is improved over 20%, and energy saving of the hybrid system is calculated as over 30% compared to conventional all air type in the case of heating. And also the results showed that humidity decreased about $5{\sim}6%$, also characteristics of thermal control is improved over 34%.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.89-94
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• 2008

In this study it was evaluated that hybrid air conditioning and ventilation system to reduce energy consumption and keep on comfortable indoor environment in an underground shopping center. Room temperature by hybrid HAVC system was controled as $1.8{\sim}2.1^{\circ}C$ low and indoor humidity was controled as $4.1{\sim}5.0%RH$ low, and response was fast in $2.0{\sim}2.5$ times compared with conventional system. And also transportation efficiency of hybrid HVAC system was improved in about 27%, and total energy consumption rate of hybrid HVAC system is decreased in 16% compared with conventional system.