• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.717-718
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• 2009

국가R&D정보표준은 과학기술기본법 제7조 및 동법 시행령 제41조에 의거하여 국가R&D정보의 체계적인 수집 연계 및 공동활용 기반구축 등에 활용하고자 범부처 차원에서 국가R&D사업 현황파악, 종합조정, 공동활용하기 위한 필요 최소한의 정보를 공유 활용하기 위한 표준정보이다. 2007년 8월 과학기술관계장관회의에서 341개의 항목으로 구성된 국가R&D정보표준이 제정되었고, 2009년 7월 국가과학기술위원회 운영위원회에서 340개의 항목으로 개정되었다. 본 논문에서는 국가R&D정보표준의 2009년 7월 개정내용과 그에 따른 데이터 모델링 결과를 제시함으로써, 15개 부처 청 14개 대표전문기관 및 연구관리기관 업무 담당자들과 R&D종사자들에게 NTIS에서 수집 공유 활용되는 국가R&D정보에 대한 이해와 활용을 증진시키고자 한다.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.495-500
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• 2006

Nowadays HCFCs refrigerant are restricted because it cause depletion of ozone layer. However, natural gases such as ammonia as an organic compound, propane and propylene as hydrocarbon are easy and cheap to obtain as well as environmental. Accordingly, this experiment apply the $NH_3$ and R22 to study the performance characteristic from the superheat control and compare the energy efficiency of two refrigerants from the high performance. The condensing pressure of refrigeration system is increased from 15bar to 16bar and degree of superheat is increased from 0 to $10^{\circ}C$ at each condensing pressure. As the result of experiment, when comparing the each COP, we knew the $NH_3$ is suitable as the alternative refrigerant of the R22.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1427-1433
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• 2012

In this paper, cycle performance analysis of cascade refrigeration system using alternative FREON refrigerants and natural refrigerants are presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooled and superheated degree, and condensing and evaporating temperature, temperature difference of cascade heat exchanger in cascade refrigeration system. The COP of cascade refrigeration system increases with the increasing subcooled degree, but there is no significant changes with the increasing superheated degree. The COP of cascade refrigeration system depends on evaporating and condensing temperatures of cascade heat exchanger. Therefore, subcooled degree, evaporating and condensing temperature of cascade heat exchanger using alternative FREON refrigerants and natural refrigerants have an effect on the COP of this system. In this paper, COP of cascade refrigeration system using (R23 / R290), (R23 / R600), (R23 / R600a), (R23 / R717), (R744 / R404A) are higher 20 ~ 36 % than (R23 / R22), using R23 for low temperature system and R22 for high temperature system.

• Journal of the Korean Mathematical Society
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• v.34 no.3
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• pp.707-717
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• 1997

The square of Brownian density process $Q^\lambda$ is defined where $\lambda$ is a parameter. Applying limit theorems of stochastic integrals w.r.t. martingale measure, we prove a weak limit theorem for $Q^\lambda$ in $D_{S'(R^d)}[0,1]$.

• Journal of the Korean Institute of Gas
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• v.16 no.3
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• pp.42-47
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• 2012

In this paper, alternative natural refrigerant R290(Propane), R600(Butane), R717(Ammonia), R1270(Propylene) for freon refrigerant R22 were used working fluids for 2-stage compression and 1-stage expansion refrigeration system. The operating parameters considered in this study included evaporation temperature, condensation temperature, subcooling degree, superheating degree, mass flow rate ratio of inter-cooler. The main results were summarized as follows : The COP of 2-stage compression and 1-stage expansion refrigeration system increases with the increasing subcooling degree and mass flow rate ration of inter-cooler, but decreases with the increasing evaporating temperature, condensing temperature and superheating degree. Therefore, subcooling degree, mass flow rate ratio of inter-cooler of 2-stage compression and 1-stage expansion refrigeration system using natural refrigerants have an effect on COP of this system. The COP of natural refrigerants was higher than the COP of freon R22 in this study, so points to be considered are the security, the attached facilities for natural refrigerants than COP.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.839-845
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• 2021

In this study, it shows the efficiency of each refrigerant through simulation method for ORC (Organic Rankine Cycle) power generation that converts waste heat discarded by ship exhaust into electricity for the purpose of reducing CO₂ emission and increasing ship waste heat recovery. by Simulation was performed with waste heat from the exhaust gas which is relatively high temperature and cooling sea water which is relatively low temperature from ships. As a result of the sea water cooling ORC power generating system, efficiency of the working fluid with R717 is highest as a 2.86 % and the next working fluid is R152a, R134a, R143a and R125a.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1969-1973
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• 2007

The purpose of this study is to investigate the performance of a sea 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 $10^{\circ}C$. 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.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.5 no.1
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• pp.7-11
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• 2009

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 $10^{\circ}C$. 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.

• Journal of applied mathematics & informatics
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• v.7 no.3
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• pp.709-717
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• 2000

In addition to some new cubature formulas for the approximation of integrals over the unit disk, we present a survey of all known cubature formulas of algebraic degree for this region.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.717-718
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• 2010