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      • KCI우수등재

        공동주택단지 난방시스템들에 대한 경제성 평가

        조금남,윤승호,김원배 대한설비공학회 1998 설비공학 논문집 Vol.10 No.6

        The heating system for apartment complex may be classified as old systems including central system with steam boiler(S1), gas engine driven heat pump system(S2), system using waste heat(S3) and new systems including mechanical vapor re-compression system with flashing heat exchangers(S4), system using methanol(S5), system using metal hydride (S6). The purpose of the present study is to suggest optimal heating system by technically, economically and environmentally evaluating old and new heating systems of apartment complex from 500 to 3,000 households. Economic evaluation based on the technical evaluation results which estimated heat transfer area of heat exchangers and capacity of equipments was estimated initial investment cost, annual operating cost and relative payback period by considering annual increasing rates of energy cost and interest. Environmental evaluation provided annual generation rate of carbon dioxide. Initial investment cost was cheap in the order of S6, S5, S3, S2, S4, S1, annual operating cost was cheap in the order of S1, S2, S4, S5 and relative payback period was short in the order of S6, S5, S2, S3 and S4. Relative payback period was within 8 years for all scenarios of 3,000 households, and was increased as annual increasing rates of energy cost and interest were increased. As transportation pipe length was increased twice, payback period was increased by 1.4~2.6 time. The effect of temperatures of waste gas and waste water on the relative payback period was small within 0.8 years. The annual generation rate of carbon dioxide was big in the order of S4, S2 and S1. S4 was the most economic system among whole scenarios when S1 was replaced with other scenarios.

      • KCI우수등재

        마이크로핀관 증발기내 전열 성능에 미치는 냉동기유의 영향

        조금남,태상진,Cho, Keumnam,Tae, S.J. 대한설비공학회 1999 설비공학 논문집 Vol.11 No.1

        The present study experimentally investigated the effect of refrigeration lubricant on the heat transfer performance in the straight sections and U-bend of a microfin tube evaporator by using R-22/mineral oil and R-407C/POE oil. The apparatus consisted of test section with U-bend, preheater, condenser, oil injection and sampling devices, magnetic pump, mass flow meter etc. The experimental parameters were oil concentration of 0 to 5 wt%, inlet quality of 0.1 to 0.5, mass flux of 219 and $400kg/m^2s$ and heat flux of 10 and $20kW/m^2$. The effects of parameters on the heat transfer coefficients were large in the order of inlet quality, mass flux and heat flux as oil concentration got increased. As oil concentration was increased, heat transfer coefficients were continuously decreased for R-22 and increased by 3% up to the concentration of 1% and then decreased for R-407C under the condition of large inlet quality, and small mass flux and heat flux. But, the heat transfer coefficients were increased up to the concentration of 3% and then decreased for both R-22 and R-407C refrigerants under the opposite conditions. The variation of enhancement factors for R-407C was under 50% of that for R-22 and the variation with respect to the positions in the test section was small. The pressure drops were increased for both R-22 and R-407C refrigerants as oil concentration was increased. The pressure drops for R-407C were smaller by the maximum of 18% than those for R-22.

      • KCI우수등재

        파라핀 축열재를 사용한 구형캡슐 시스템의 전열성능

        조금남,최승학,Cho, K.N.,Choi, S.H. 대한설비공학회 1997 설비공학 논문집 Vol.9 No.3

        The purpose of the present work is to show the best thermal storage material and the sensitivity of the parameters on the thermal performance by experimentally investigating the effects of the parameters on the thermal performance of the spherical capsule system using paraffins superior to the commercial one. The paraffins were n-Tetradecane and the mixture of n-Tetradecane 40% and n-Hexadecane 60%. The experimental parameters were the Reynolds number of 8, 12, and 16 and the inlet temperature of-7, -4, -1, and $2^{\circ}C$. The charging and the discharing time, the dimensionless thermal storage amount, and the averge heat transfer coefficient in the tank were obtained by utilizing the local temperature variation in the tank. The local charging and discharging time in the tank was axially and radially different a lot. The effects of the inlet temperature on the charging and the discharging time were larger during the charging process than during the discharging process, but the effects of the Reynolds number on the charging and the discharging time were in reverse order. The paraffins were better by 11~72% than the water with the inorganic material in the charging time aspect, but no difference in the discharging time aspect. The effects of the Reynolds number on the dimensionless thermal storage amount were smaller than the effects of the inlet temperature during the charging process, but in reverse order during the discharging process within the working range of the experimental parameters. The effects of the inlet temperature and the Reynolds number on the average heat transfer coefficient were larger during the discharging process than during the charging process. The average heat transfer coefficient for the paraffins was larger by 40% maximum than that for the commercial material during the charing and the discharging process.

      • 천연가스 부하관리

        조금남,김용찬,Jo Geum-Nam,Kim Yong-Chan 대한설비공학회 2006 설비저널 Vol.35 No.7

        천연가스 부하관리 국내외 사례, 합리적인 평가 체계 방법을 제시하고자 한다.

      • 순수점성 비뉴톤유체의 물성치들에 대한 농도 및 온도의 영향

        조금남 대한기계학회 1994 대한기계학회논문집 Vol.18 No.3

        The thermophysical properties of Non-Newtonian fluid as the function of the temperature and the concentration are needed in many rheological heat transfer and fluid mechanics problems. The present work investigated the effects of the concentration and the temperature on the thermophysical properties of purely-viscous Non-Newtonian fluids such as the isobaric thermal expansion coefficient, density, zero-shear-rate viscosity, and zero-shear-rate dynamic viscosity within the experimental temperature range from $25^{\circ}C$ to $55^{\circ}C$. The densities of the test fluids were determined as the function of the temperature by utilizing a reference density and the least square equation for the measured isobaric thermal expansion coefficient. As the concentration of purely-viscous Non-Newtonian fluid was increased up to 10,000 wppm, the densities were proportionally increased up to 0.4%. The zero-shear-rate viscosities of test fluids were measured before and after the measurements of the first thermal expansion coefficients and the densities of Non-Newtonian fluid. Even though they were changed up to approximately 22% due to thermal aging and cycling, they had no effects on the thermal expansion coefficients and the densities of Non-Newtonian fluid. The zero-shear-rate dynamic viscosities for purely-viscous Non-Newtonian fluids were compared with the values for distilled water. They showed the similar trend with the zero-shear-rate viscosities due to small differences in the densities for both distilled water and purely-viscous Non-Newtonian fluid.

      • KCI등재

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