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김민수,장세동,노승탁,Kim, M.S.,Chang, S.D.,Ro, S.T. 대한설비공학회 1992 설비공학 논문집 Vol.4 No.1
Experimental investigation on the performance of a heat pump system using refrigerant mixtures is done. The condenser and the evaporator are double pipe heat exchangers of counter flow type and the compressor is driven by a variable speed motor. The refrigerant mixture used in the experiment is R22/R142b. Experiments are performed by changing the compressor speed, composition on ratio of mixture, and the average temperatures of condenser and evaporator. The compressor work, heating capacity and the coefficient of performance are calculated. Results show that the heating capacity can be changed by varying the mass flow rate of refrigerant mixtures to meet the heating load. It is shown that the capacity control by changing the composition ratio is more effective than by changing the compressor speed. Under the condition where the external conditions are fixed and the heating loads are equal, the coefficient of performance has its maximum value near 50 : 50 mass fraction of the refrigerant mixture in this study.
김민수,김동섭,원성필,노승탁,Kim, M.S.,Kim, T.S.,Won, S.P.,Ro, S.T. 대한설비공학회 1990 설비공학 논문집 Vol.2 No.3
Studies on the performance of a heat pump using non-azeotropic refrigerant mixtures are done. In order to estimate the thermodynamic properties for the selected non-azeotropic refrigerant mixtures including R22/R152a, R22/R142b, R22/R114 and R13B1/R152a, Peng-Robinson equation of state is adopted. The pressure-enthalpy diagram and the temperature-entropy diagram are plotted for each refrigerant mixture. Considerations on the capacity modulation for the heat pump system using refrigerant mixtures are taken into. Results show that when the heating load varies, the possibility for the capacity modulation is found in the heat pump system using a compressor with constant volume flow rate. Under a constant heating capacity condition in the heat pump system, the coefficient of performance increases when the refrigerant mixtures are used. The volume flow rate decreases as the mass fraction of lower boiler increases in this case.
김민수,Kim, M.S. 대한설비공학회 1993 설비공학 논문집 Vol.5 No.3
Nonflammable mixtures of flammable and nonflammable refrigerants are possible as substitute refrigerants for use in domestic heat pumps and refrigerators. Refrigerant leakage from such a system is of paramount concern since it is possible that the resulting mixture composition remaining in system will reside in the flammable range. This paper presents a simulation of a leakage process of refrigerant mixtures. Idealized cases of isothermal leakage process are considered in this study representing a slow leak. Simulation is performed for selected composition of binary and ternary refrigerant mixture; R-32/134a and R-32/125/134a. Mixture compositions with respect to percentage leak of original charge are presented. In isothermal leakage process, both vapor and liquid compositions of more volatile refrigerant decrease during vapor and liquid leak, but the total composition of this component decreases during vapor leak and increases during liquid leak. Vapor and liquid compositions are determined depending on the vapor-liquid equilibrium relation of the refrigerant mixture. The refrigerant mixture left in the system can go to a nonflammable direction relying on which component in the mixture is flammable.
김민수,이용준,박종현,Kim, M.S.,Lee, Y.J.,Park, J.H. 한국전자통신연구원 2007 전자통신동향분석 Vol.22 No.3
최근 들어 인간 중심의 정보화 사회가 USN 기술의 발전과 더불어, 사물 간에도 정보들이 유기적으로 결합되고 활용될 수 있는 유비쿼터스 컴퓨팅 사회로 급격히 변모하고있다. 이러한 유비쿼터스 컴퓨팅 사회를 성공적으로 구축하기 위해서는 센서노드 하드웨어, 센서 네트워크, USN 미들웨어, 그리고 USN 응용 서비스 등의 USN 핵심기술의개발이 반드시 필요하게 된다. 본 논문에서는 USN 응용 시스템과 센서노드 하드웨어의 중간 부분에 위치하여, 이 둘 간의 유연한 통합을 지원할 수 있는 USN 미들웨어 기술에 대하여 자세히 소개하고자 한다. 먼저, Server-side 미들웨어와 In-network 미들웨어로 구성된 USN 미들웨어의 개념, USN 미들웨어가 제공해야 할 핵심기능들, 그리고 기존에 발표된 USN 미들웨어의 특징에 대하여 살펴보고, 이러한 USN 미들웨어의 특징을 반영하여 현재 ETRI에서 개발되고 있는 USN 미들웨어 플랫폼의 시스템 구성과 이를 활용한 응용 시스템에 대하여 간략히 살펴볼 것이다.