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장기창(Ki-Chang Chang),백영진(Young-Jin Baik),나호상(Ho-Sang Ra),김지영(Ji-Young Kim),이재훈(Jea-Hun Lee) 한국지열·수열에너지학회 2009 한국지열에너지학회논문집 Vol.5 No.1
The purpose of this study is to investigate the performance of a water heat source cascade heat pump system R717(Ammonia) is used for a low-stage working fluid while R134a is for a high-stage. In order to gain a high temperature supply water in winter season, the system is designed to perform a cascade cycle. In this study, two experiments were carried out. One is a system starting test from the low load temperature of 10℃. The other is a system performance investigation over the R717 compressor capacity changes. Experimental results show that when it starts from the low load temperature, the suction temperature of the low-stage compressor is higher than that of a high-stage. The system performance increases when a water source temperature or a low-stage compressor rotational frequency goes higher.
장기창(Chang, Ki-Chang),백영진(Baik, Young-Jin),윤형기(Yoon, Hyung-kee),나호상(Ra, Ho-Sang) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
A sea water source cascade heat pump was designed and tested in this study. The system was designed to perform a single stage operation in summer, as well as a cascade operation in winter to ensure the high temperature lift. A steady-state simulation model was developed to analyze and optimize its performance. The simulation results show that the R717 exhibits best performance among combinations considered in this study. A R410A also exhibits the highest performance among HFCs with the smallest compressor displacement. A 15-RT R410A-R134a pilot system was installed in the 5-story commercial building at Samcheok City by the East Sea. A scroll type R410A compressor, a reciprocating type R134a compressor, plate type condenser/evaporator/ cascade heat exchanger and two electronic expansion valves were used to build a pilot. A titanium plate type heat exchanger is also used for the heat exchanging with a sea water. The heat source/sink water is supplied from the well below the seashore in the depth of 5 m. In the initial test of the system, supply water temperature was rising up to 67?C using a sea water heat source of 9?C, while an ambient temperature was 4.5?C.
장기창 ( Jang Gi Chang ),김성철 ( Kim Seong Cheol ),송은영 ( Song Eun Yeong ),김공호 ( Kim Gong Ho ),권혁모 ( Kwon Hyeog Mo ),강상헌 ( Kang Sang Heon ),박기훈 ( Park Gi Hun ),정용환 ( Jeong Yong Hwan ) 한국응용생명화학회 2003 Applied Biological Chemistry (Appl Biol Chem) Vol.46 No.3
In order to isolate antibacterial substances from the rhizome of Zingiber mioga Roscoe, the ethanol extracts was fractionated according to the activity against Bacillus subtilis B. cereus and Staphylococcus aureus. Three antibacterial substances were isolated and purified by column chromatography and recrystallization. Compounds Ⅰ and Ⅲ showed activity against all the tested bacterias and compound Ⅱ exhibited the activity against B. subtilis and B. cereus except S. aureus. Compound I was examined antimicrobial activity aginst B. .subtilis, B. cereus and S. aureus by optical density using Bioscreen C Compound I showed strong growth inhibition at 10 ppm on B. subtilis and B. cereus for 72 hrs, and at 25 ppm on s. aureus. On the basis of spectrometric studies including ¹H-NMR, ^(13)C-NMR, DEPT, 1H-1H COSY, HMQC, HMBC and IR, compounds Ⅰ, Ⅱ and Ⅲ were identified ai (E)-8β(17)-epoxylabd-12-ene-15,16-dial (C_(20)H_(30)O₃, MW=318), galanolactone (C_(20)H_(30)O₃, MW=318) and galanal A(C_(20)H_(30)O₃, MW=318), respectively. These results are the first reports on the isolation (E)-8β(17)-epoxylabd-12-ene-15,16-dial, galanolactone and galanal A from the rhizome of Zingiber mioga.
장기창(Chang, Ki-Chang),백영진(Baik, Young-Jin),김민성(Kim, Min-Sung),이영수(Lee, Young-Soo),박성룡(Park, Seong-Ryong),나호상(Ra, Ho-Sang) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.05
In this study, a geothermal power generation system using the Kalina cycle was investigated by the simulation method. The Kalina cycle system can be used for the utilization of a low-temperature heat sources such as geothermal and industrial waste heat that are not hot enough to produce steam. The sea/river water can be considered as a cooling media. A steady-state simulation model was developed to analyze and optimize its performance. The model contains a turbine, a pump, an expansion valve and heat exchangers. The turbine and pump were modelled by an isentropic efficiency, while a condenser, an evaporator and a regenerative heat exchanger were modeled by UA-LMTD method with a counter-flow assumption. The effect of the ammonia fraction at the separator inlet on the cycle performance is investigated in detail.