• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.8
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• pp.756-761
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• 2004

Since the use of CFC and HCFC refrigerants are to be restricted due to the depletion of ozone layer, this experiment applies the NH$_3$ gas to study the performance characteristics from the superheat control for improving the energy efficiency. The experiments are carried out for the condensing pressure of refrigeration system from 14.5 bar to 16.0 bar by 0.5 bar and for superheat temperature from $0^{\circ}C$ to 1$0^{\circ}C$ by 1$^{\circ}C$ at each condensing pressure. As a result of experiment, when the superheat temperature is 1$^{\circ}C$ at each condensing pressure, the refrigeration system has the highest performance.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1334-1339
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• 2004

Nowadays CFCs and HCFCs refrigerants are restricted because it cause depletion of ozone layer. Accordingly, this experiment apply the $NH_3$ gas and not CFCs and HCFCs for refrigerant to study the performance characteristic from the superheat control and improve the energy efficiency from the high performance. The condensing pressure of refrigeration system is increased from 14.5bar to 16bar by 0.5bar and superheat temperature is increased from $0^{\circ}C$ to $10^{\circ}C$ by $1^{\circ}C$ at each condensing pressure. As the result of experiment, when the superheat temperature is $1^{\circ}C$ at each condensing pressure, the refrigeration system has the high performance.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.573-576
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• 2016

In this study, hydrogenation of 1,2,3,3,3-pentafluoropropene was performed to produce R-1234yf as an environmentally friendly refrigerant. Palladium based carbon was prepared as a catalyst in the hydrogenation reaction. The effect of reaction conditions including the weight hourly space velocity (WHSV), reaction temperature and ratio of hydrogen and reactants on the catalytic performance was investigated. Under the identical reaction conditions, the effect of WHSV on the main product selectivity was insignificant, but a high reaction temperature was essential for the good product selectivity. A high product selectivity was also obtained when the ratio of hydrogen and reactants kept less than 1.5. Moreover, a correlation model involving the statistical approach to predict product yields was developed.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.554-554
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• 2009

지구온난화는 범지구적 환경문제로 매우 빠른 속도로 진행되면서 그 심각성을 더해가고 있다. 특히 해수면 상승이나 대형 태풍, 홍수, 가뭄 등의 이상기후가 빈번하게 발생되며 생태계에도 심각한 타격을 주고 있다. 이러한 지구온난화를 유발하는 물질들에 대해 도쿄의정서(Annex A)에 6대 온실가스($CO_2$ (이산화탄소), 메탄($CH_4$), $N_2O$(아산화질소), PFC(불화탄소), HFC(수소화불화탄소), $SF_6$(육불화황))로 정의 하여 규제대상으로 분류하고 있다. $CO_2$를 제외한 Non-$CO_2$ 온실가스들은 배출량이 $CO_2$에 비해 매우 낮지만 GWP(지구온난화지수)가 매우 커 지구온난화에 미치는 영향이 상당하다. 최근 이산화탄소 이외에 지구온난화 문제를 일으키는 온실가스에 대한 많은 관심으로 대상가스의 처리 또는 재활용을 위한 신기술 및 신공정 개발에 박차를 가하고 있다. 온실가스 중 HFCs는 GWP가 1300으로 미량의 배출로도 심각한 기후변화를 일으킬 수 있는 물질로, 우리나라의 경우 1990년 이후 HFCs 배출량 증가율은 연 평균 4.9% ~ 13.8%이다. 국내외 온실가스 처리기술은 대부분 CO2에 대한 연구개발 및 실증화가 지배적이고, non-CO2에 대한 처리기술 개발수준은 미흡할 뿐만 아니라 본 연구 대상인 HFCs 의 경우에는 처리기술 연구개발이 전무하다. 특히 HFCs는 냉매 또는 발포제로 사용되는데 일반적으로 사용 후 특별한 처리과정 없이 대기중으로 배출된다. 본 연구에서는 non-CO2 가스인 HFC-134a 를 대상으로 혼합가스에서 분리 회수를 위해 하이드레이트 기술을 접목시켜 경제적, 친환경적인 기술개발을 목적으로 한다. kinetic 반응장치와 고압반응기 및 magnetic drive system 을 이용하여 stirring speed와 driving force에 따른 HFC-134a 하이드레이트 형성속도의 상관관계를 제시하고자 한다.

• The Magazine for Energy Service Companies
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• s.38
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• pp.78-81
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• 2006

지역난방공사 광주에 구역형 집단에너지사업 추진/대한상의 기업 70% 에너지절약 설비 투자계획/미국 수소불화탄소 줄이기 운동/산업자원부 올신·재생에너지 지원금 4095억원/윌로펌프 세계최초 저소음 상향식 가압펌프 개발/한국수자원공사 시화호조력발전단지 CDM사업 승인/포스코건설 고양시 환경에너지시설 사업자 선정/산자부 제1차관에 김종갑 특허청장 내정/열병합발전협회 정기총회 및 이사회 개최/에관공 M&V보완·관리업무 ESCO영역 추가/청주도시가스 열병 합 발전 설명회 열어/뉴욕주 에너지 절약 납세자에 세금감면 혜택/삼성엔지니어링 매출액은 감소,순이익은 증가/한국하니웰 A&S International의 '2005 올해의 우수제품'에 선정/에너지경제연구원 아주대 인력양성 MOU체결/코오롱정보통신 "에너지 서비스사업 진출"

• Membrane Journal
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• v.27 no.5
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• pp.389-398
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• 2017

The most important characteristic of the polymer electrolyte membranes (PEMs) for fuel cells, the proton conducting ability is mainly influenced by the distribution and morphology of the water channels inside the PEMs. Non-perfluorinated hydrocarbon PEMs are known to have weaker water channels than perfluorinated PEM, Nafion, and thus relatively low proton conducting ability. In this study, we used a mesoscale simulation technique to observe the water channel formation and phase separation behavior of hydrocarbon PEM, sulfonated polyimides, under the humidification condition. It was observed that the water molecules were distributed evenly through the entire hydrophilic region, and clear water clusters were formed only in the sulfonated polyimide having high sulfonation degree. In addition, it was observed that sulfonated polyimides have a difficulty in forming water channel under the low hydrated condition. These results clearly support the theories of the formation of water channels in non-perfluorinated hydrocarbon PEMs, and also well explain the tendency of proton conducting abilities of sulfonated polyimides. Thus, it is confirmed that mesoscale simulation techniques can be very effective in analyzing phase separation behavior and water channel formation in PEMs for fuel cells and elucidating the ion conducting abilities.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.12
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• pp.1132-1138
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• 2005

Recently, production and use of freon substances are restrained due to depletion of ozone layer and global warming. In this aspect of environmental problems, the best solution is to use the natural refrigerant such as ammonia. Thus, this study is to find the optimal operating conditions by comparing the performance between the shell and tube type and shell and disk type heat exchangers using the ammonia refrigerant, and to verify the superiority of the shell and disk type heat exchanger that is not used in field of refrigeration and air conditioning. Finally, this study shows that the shell and disk type heat exchanger is applicable to the ammonia refrigeration system, and this system minimizes the refrigerant charge and installation space.

• Journal of Hydrogen and New Energy
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• v.20 no.4
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• pp.323-330
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• 2009

Efficiency of a fuel cell is determined by the generated water. If water is not removed sufficiently, water will be accumulated at GDL, which causes flooding. Therefore, water control is regarded as a crucial factor to sustain fuel ell performance. In this study, PTFE coating on the surface of carbon paper was carried out to establish optimum process for hydrophobic treatment of GDL. Carbon paper was immersed at different concentrations of nano-sized PTFE coating solution. Their characteristics were analyzed systematically by FE-SEM, water contact angle, cyclic voltamogam, XRD and FT-IR. The quantitative correlation between the amount of coated-PTFE on a carbon paper and concentration of coating solution was carefully investigated. It is suggested that the amount of PTFE-coating on a carbon paper can be managed by means of controling concentration of coating solution.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.379-384
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• 2005

Polyurethane foams (PUFs) were prepared from polymeric 4,4'-diphenylmethane diisocyanate (PMDI), seven polyols with different functionalities and OH values, silicone surfactant, two catalysts, and three blowing agents. Chlorofluorocarbon (CFC-11), hydrochlorofluorocarbon (HCFC-141b) and hydrofluorocarbon (HFC-365mfc) were used as blowing agents. The effect of gelling and blowing catalysts on basic properties and cell structure of PUF with HCFC-141b was investigated. The cell size of the PUF decreased with an increase in the amount of catalyst from 0 to 2 pph (parts per hundred polyol). In the case of gelling type catalyst, the compressive strength increased from 11.9 to $12.66kg_f/cm^2$ with an increase in the amount catalyst from 0 to 2 pph but the density did not change significantly. The gelling time, density, and compressive strength of the PUF with three different blowing agents were measured. There was no detectable change in their properties. However, the cell structure of PUF with HCFC-141b was not uniform as in the other systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.297-302
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• 2005

Since the use of CFC and HCFC refrigerants are to be restricted due to the depletion of ozone layer, this experiment applies the $NH_3$ gas to study the performance characteristics of $NH_3$ refrigeration system by the superheat control for improving the energy efficiency. The experiments are carried out for the condensing pressure of refrigeration system from 1,500 kPa to 1,600 kPa and for degree of superheat from $0^{\circ}C\;to\;10^{\circ}C$ at each condensing pressure. As a result of experiment, when the degree of superheat is $0^{\circ}C$ at each condensing pressure, the refrigeration system has the highest performance.