• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.23 no.4
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• pp.326-330
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• 1994

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.23 no.5
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• pp.414-420
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• 1994

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.23 no.1
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• pp.53-59
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• 1994

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.25 no.4
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• pp.315-322
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• 1996

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.25 no.4
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• pp.334-341
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• 1996

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.23 no.2
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• pp.143-148
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• 1994

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.8
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• pp.1109-1112
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• 2000

A field experiment was carried out to determine the effects of mechanical and chemical conditioning at mowing on field drying rate and quality of grass hay in 1996. Mower conditioner and/or chemical drying agent $(K_2CO_3)$ were used at different harvest stages (late boot, heading and bloom stages) for hastening hay-making. After field drying, square bales were made by hay baler, and the visual estimation and nutritive value of hay were evaluated after storing two months. In mower conditioning, the duration of field drying was shortened by 0.5 to 1 day compared with drying agent, and by 1 to 2 days compared with control. The drying matter loss of hay was reduced by late harvest and mechanical conditioning. The visual score (leafiness, green color, odor and softness), and acid detergent fiber (ADF), neutral detergent fiber (NDF), in vitro dry matter digestibllity (IVDMD), and relative feed value (RFV) of hay were improved with mechanical conditioning, but chemical alone had little effect on quality. The quality of hay harvested at bloom stage was much lower than that of hay harvested at late boot and heading stage. In conclusion, mower conditioning can enhance the field drying rate of grass hay, however the drying efficiency of chemical drying agent is very low. Also the effects of chemical/mechanical combined conditioning are very similar compared with mechanical conditioning alone. Harvesting at late boot to heading stage is recommended for the production of high quality hay.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.67-75
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• 2007

This paper deals with the research for the effects of the operating parameters that could be used for a transcritical $CO_2$ mobile air-conditioning system on the cooling performance. The experimental conditions of the performance tests for a system and components such as a gas cooler and an evaporator were suggested to compare the performance of each with the standardized test conditions. And this research presents experimental results for the performance characteristics of a $CO_2$ mobile air conditioning system with various operating conditions such as different gas cooler inlet pressures and frontal air velocities/temperatures passing through an evaporator and a gas cooler. Experimental results show that the cooling capacity was more than 5kW and coefficient of performance (COP) was more than 2.1, also. Therefore, we checked that the mobile air-conditioning system using $CO_2$ has good performance compared to that using HFC-134a.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.6
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• pp.321-327
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• 2015

This study presents an HFC152a refrigerant air conditioner as an alternative to HFC134a, which is currently used in mobile air conditioning systems. Cool-down performance tests of an HFC152a air conditioning system were conducted and compared to a baseline HFC134a air conditioner. The experimental set-up consisted of a belt-driven compressor, a sub-cooled type condenser, an evaporator, and a block-type thermal expansion valve (TXV). A drop-in test was carried out on the mobile air conditioning system under various vehicle running speeds in a climate-controlled wind tunnel (CWT). Additionally, to optimize the HFC152a air conditioning system, the effects of the TXVs on the performance were studied. The results show that compared to the HFC134a air conditioning system, the refrigerant charge quantity was reduced by approximately 20%, the discharge pressure was reduced by about 350~430 kPa, and the air discharge temperature at vehicle running conditions was $0.5{\sim}1.5^{\circ}C$ lower. In addition, good compressor durability was expected due to the lower compression ratio.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.1
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• pp.110-119
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• 1996

A numerical of thermoacoustic refrigerators has been developed. Effects of heat transfer and viscosity on pressure and velocity distributions in resonators and heat exchangers were considered. Predictions of cooling capacity and COP agreed well with previous experimental results. Effects of important design parameters, such as pressure ratio, spacing between the plates in the stack and stack length, on the performance of thermoacoustic refrigerators were shown.