• 대한설비공학회지:설비저널
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• 제25권3호
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• pp.268-277
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• 1996

• 대한설비공학회지:설비저널
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• 제25권4호
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• pp.348-353
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• 1996

• 대한설비공학회지:설비저널
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• 제23권2호
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• pp.149-167
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• 1994

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.863-868
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• 2009

The drag reduction(DR) for Betaine+Amin and Xantan Gum as kinds of surfactant and Polyacrylamide as kinds of polymer solution according to the fluid velocity, temperature and surfactant concentration were compared experimentally. For this study, two kinds of experimental apparatus for short time and long time measurement were established. Each experimental appratus was equipped with hot water storage tanks, pumps, testing pipe network, flowmeter, two pressure gauges and data logging system was built for them. Results showed that Betaine+Amin and Xanthan Gum as kinds of surfactant had appeared optimal DR around 200-500 ppm and their DR tended to be decreased when flow velocity increased but Polyacrylamide as kinds of polymer solution showed the opposite trend to be increased when flow velocity increased. The both of them showed above 40% DR in the case of better condition by the short term measurement. But Polyacrylamide as kinds of polymer solution showed more degradation than Betaine+Amin and Xanthan Gum as kinds of surfactant by the long term measurement. As a result, Betaine+Amin and Xanthan Gum as kinds of surfactant showed better materials to use to the district heating system.

• 설비공학논문집
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• 제12권3호
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• pp.251-257
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• 2000

District heating and cooling systems offer highly efficient energy utilization and maintenance by centralizing heat management. More pumping power, however, is required because the water has to travel long distance from heat source to the users. In the present study, a trace of drag reduction additives is added to the District Cooling system to achieve a significant drag reduction and save pumping power. Water-soluble polymers, surfactants, and environment-friendly degradable polymers are used as effective drag reducing additives. Time dependent percent drag reductions are compared for various additive solutions at 100 wppm concentration for different water velocity. Without as an anionic surfactant, copolymer was most effective in percent drag reduction. It is found that there exists an optimal condition when copolymer is mixed with SDS. An environment-friendly degradable polymer, xanthan gum, is found to be a significant drag reduction additive. Ice slurry systems, can give less pressure drops compared with chilled water system for certain condtions. Drag reduction additives were also effective for the ice slurry system.

• 전기학회논문지
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• 제60권1호
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• pp.214-220
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• 2011

This paper studies about the assessment of thermal performance between wet ondol system and electric ondol system. Electrical ondol systems shows faster warm-up time, higher floor surface temperature distribution and lower power consumption than wet ondol system. However, if we provide heat regularly wet ondol system which has more heat capacity shows greater thermal storage than electric ondol system. Therefore, we could conclude that wet ondol system which keeps temperature regularly by the thermal storage show better energy-efficiency in case of using the central heating and district heating system. However, Electrical ondol system shows better efficiency in case of using the space during short time or individual heating systems which needs to heat quickly. The Experiment says that electric ondol system has more benefits on timing to reach the set temperature and energy-efficiency than wet ondol system.

• 설비공학논문집
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• 제9권3호
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• pp.401-409
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• 1997

The long term drag reduction characteristics of Habon-G solution were investigated in the KIER pilot-scaled district heating simulation system. Test runs were implemented for 30 days without interruption. Pressure drop, flow rate and power consumption of surfactant (Habon-G) solution were regularly observed and compared with those of plain water. The experimental results suggest that the surfactant can be effectively applied to the DH transmission system for considerably long period wthout significant loss of its drag reduction capability even though the concentration of the additive may gradually decrease in the first stage of the experiment because of absorption.

• 설비공학논문집
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• 제27권5호
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• pp.247-253
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• 2015

The presented work demonstrates the effects of flow rate on the secondary side of DHS (District Heating System). Increasing flow rate at the secondary side of DHS decreases energy consumption and time to reach the set-point of the heated room while increasing heat flux on the floor in the heating space. When flow rate increases, the overall heat transfer rate of radiant floor also increases. However, the results also show overall heat transfer rateto not increased linearly and thus the existence of an optimal flow rate for the secondary side of DHS. Control of the radiant floor with hot water may be more effectively accomplished with a combined control strategy that includes heat flux and a temperature set-point. This experimental analysis has been performed using a lab-scaled DHS pilot plant located at Jeonju University in Korea.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제24권1호
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• pp.24-32
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• 2018

본 논문은 산업 현장과 민간에서 실시간으로 수집되는 에너지 빅데이터를 수용하는 빅데이터 시스템을 제안한다. 구축된 빅데이터 시스템은 하둡(Hadoop) 기반이며, 빅데이터 처리에 있어 인메모리(in-memory) 분산처리 컴퓨팅을 지원하는 스파크(Spark) 프레임워크가 동시에 적용되었다. 본문에서는 지역난방에 사용되는 열에너지 형태의 빅데이터에 초점을 두어, 입출력되는 에너지의 특성을 고려하며 실시간 수집되는 빅데이터를 적재, 관리, 처리 및 분석하는 방법을 다룬다. 이 때, 외부에서 유입되는 빅데이터는 시스템 내부에 설계된 관계형 데이터베이스 스키마에 따라 저장하고 관리되며, 저장된 빅데이터는 설정된 목적에 따라 처리하고 분석된다. 제안된 빅데이터 시스템과 더불어 지역난방과 관련한 복수의 실증현장으로부터 실시간으로 수집되는 열에너지 빅데이터에 대해 시스템이 활용된 사례를 기술한다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.673-678
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• 2009

This paper presents the optimization process of liquid desiccant cooling cycle using LiCl aqueous solution as a working fluid. Operating conditions and design factors for heat exchangers were optimized by response surface method. As a result, we obtained the 7.297 kW of cooling capacity and 0.788 of COP at optimized condition. Effect of $dT_{hw}$ on system performances was also examined. As $dT_{hw}$ increases, the cooling capacity increases and COP decreases.