• 대한설비공학회지:설비저널
• /
• 제15권1호
• /
• pp.62-66
• /
• 1986

• 대한설비공학회지:설비저널
• /
• 제18권5호
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• pp.411-426
• /
• 1989

• 대한설비공학회지:설비저널
• /
• 제14권1호
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• pp.48-72
• /
• 1985

• 대한설비공학회지:설비저널
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• 제18권6호
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• pp.515-531
• /
• 1989

• 대한설비공학회지:설비저널
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• 제2권3호
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• pp.189-191
• /
• 1973

• 대한설비공학회지:설비저널
• /
• 제15권4호
• /
• pp.303-310
• /
• 1986

• 대한설비공학회지:설비저널
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• 제39권8호
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• pp.23-31
• /
• 2010

• 대한설비공학회지:설비저널
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• 제37권8호
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• pp.77-82
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• 2008

• 설비공학논문집
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• 제15권12호
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• pp.1035-1042
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• 2003

As the desire for a better condition in classroom increases, the distribution rate of warming and cooling conditioners increases. But it is known that according to the way by which the equipments put and are operated the comfortableness felt by persons who are in classroom can make a difference. Therefore, proper equipments in accordance with the size of classroom should be considered as well as operational methods when ceiling warming and cooling conditioners put. This study makes conclusions as follows through a simulation to get improvements in accordance with the size of classroom and to improve the heating performance of ceiling warming and cooling conditioners in classroom.

• Tribology and Lubricants
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• 제35권4호
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• pp.206-214
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• 2019

This study investigates alternative refrigerants and refrigerant oils as well as the tendency of protecting the global environment in view of automobile air-conditioning systems. Since decades, the R12 refrigerant is not used in automobile air-conditioners because of the ozone depletion potential (ODP) problem, and for the last 20 years, the ODP-free R134a refrigerant is leading the new automotive air-conditioning market. However, owing to its high global warming potential (GWP), the R134a refrigerant use in automobile air-conditioning system is also prohibited by law, and alternative refrigerants with a low GWP need to be proposed. Therefore, recently, the application of R1234yf, R152a, or other alternative refrigerants has started worldwide. By contrast, natural refrigerant R744 was introduced in the market several years ago by VDA (Verband Der Automobilindustrie), which is a German association in the automotive industry. This study also deals with refrigerant oils. For a long time, polyalkylene glycol (PAG) oil has been traditionally used with automobile air-conditioners, and polyolester (POE) oil is suitable for HEV, PHEV, and EV air-conditioning systems, where it is used by the electrically driven compressor owing to its excellent electrical insulation properties. Finally, PAG is an excellent lubricant for all the R134a, R152a, R1234yf, and R744 refrigerants, and has the advantage that it can be applied rapidly to alternative refrigerant air-conditioning systems.