• 제목/요약/키워드: HFC152a

검색결과 19건 처리시간 0.024초

함초분 첨가 고지방식이 흰쥐의 지방대사 연구 (Glasswort Powder Diet Activates Lipid Metabolism in Rat)

  • 서효빈;곽윤영;남주옥;송영주;김병오;류승필
    • 생명과학회지
    • /
    • 제22권4호
    • /
    • pp.478-485
    • /
    • 2012
  • 본 연구에서는 함초분 섭취가 지질대사에 미치는 영향을 알아보고자 하였다. 흰쥐를 일반식이 대조군(CON), 고지방식이 대조군(HFC), 고지방식이에 함초분 첨가군(HFG)로 각각 구분하여 4주간 섭취시켰다. 체중은 HFG가 HFC에 비하여 9% 정도 낮았다. 분변칼로리 분석을 한 결과, HFG의 지방량(CON에 비하여 120%, HFC에 비하여 138)과 분변 칼로리(약 110%)가 높은 것으로 나타났다. 혈중 중성지방과 LDL-C는 HFG가 HFC에 비하여 낮았으며(각각 71.8% 및 58%), HDL-C는 HFG가 HFC에 비하여 152% 높았다. 간의 FABP 발현은 HFG가 HFC보다 197% 높았으며, CPT-1 역시 동일한 경향을 보였다. 이러한 결과는 함초분 섭취가 체중의 증가를 억제하였고, 간세포 수준에서의 지방대사를 개선하였다는 점을 시사한다. 이러한 결과를 함초분이 소화관에서의 지방흡수를 억제함으로써 항비만 효과를 가지는 것으로 제안하고자 한다.

Ab Initio Study on the Thermal Decomposition of CH3CF2O Radical

  • Singh, Hari Ji;Mishra, Bhupesh Kumar;Gour, Nand Kishor
    • Bulletin of the Korean Chemical Society
    • /
    • 제30권12호
    • /
    • pp.2973-2978
    • /
    • 2009
  • The decomposition reaction mechanism of $CH_3CF_2O$ radical formed from hydroflurocarbon, $CH_3CHF_2$ (HFC-152a) in the atmosphere has been investigated using ab-initio quantum mechanical methods. The geometries of the reactant, products and transition states involved in the decomposition pathways have been optimized and characterized at DFT-B3LYP and MP2 levels of theories using 6-311++G(d,p) basis set. Calculations have been carried out to observe the effect of basis sets on the optimized geometries of species involved. Single point energy calculations have been performed at QCISD(T) and CCSD(T) level of theories. Out of the two prominent decomposition channels considered viz., C-C bond scission and F-elimination, C-C bond scission is found to be the dominant path involving a barrier height of 12.3 kcal/mol whereas the F-elimination path involves that of a 28.0 kcal/mol. Using transition-state theory, rate constant for the most dominant decomposition pathway viz., C-C bond scission is calculated at 298 K and found to be 1.3 ${\times}$ 10$^4s{-1}$. Transition states are searched on the potential energy surfaces involving both decomposition channels and each of the transition states are characterized. The existence of transition states on the corresponding potential energy surface are ascertained by performing Intrinsic Reaction Coordinate (IRC) calculation.

대체냉매 R430A를 적용한 정수기 냉동시스템의 성능 평가 (Performance of R430A on Refrigeration System of Domestic Water Purifiers)

  • 박기정;이요한;정동수;김경기
    • 설비공학논문집
    • /
    • 제21권2호
    • /
    • pp.109-117
    • /
    • 2009
  • In this study, thermodynamic performance of R430A is examined both numerically and experimentally in an effort to replace HFC134a used in the refrigeration system of domestic water purifiers. Even though HFC134a is used predominantly in such a system these days, it needs to be phased out in the near future in Europe and most of the developed countries due to its high global warming potential. To solve this problem, cycle simulation and experimental measurements are carried out with a new refrigerant mixture of 76%R152a124% R600a using actual domestic water purifiers. This mixture is numbered and listed as R430A by ASHRAE recently. Test results show that the system performance with R430A is greatly influenced by the amount of charge due to the small internal volume of the refrigeration system of the domestic water purifiers. With the optimum amount of charge of 21 to 22 grams, about 50% of HFC134a, the energy consumption of R430A is 13.4% lower than that of HFC 134a. The compressor dome and discharge temperatures and condenser center temperature of R430A are very similar to those of HFC134a at the optimum charge. Overall, R430A, a new long term environmentally safe refrigerant, is a good alternative for HFC134a requiring little change in the refrigeration system of the domestic water purifiers.

R435A를 적용한 정수기 냉동시스템의 성능평가 (Performance Evaluation of R435A on Refrigeration System of Water Purifiers)

  • 이요한;강동규;최현주;정동수
    • 한국태양에너지학회 논문집
    • /
    • 제33권1호
    • /
    • pp.15-23
    • /
    • 2013
  • In this study, thermodynamic performance of R435A is examined both numerically and experimentally in an effort to replace HFC134a used in the refrigeration system of domestic water purifiers. Even though HFC134a is used predominantly in such a system these days, it needs to be phased out in the near future in Europe and most of the developed countries due to its high global warming potential. To solve this problem, cycle simulation and experimental measurements are carried out with a new refrigerant mixture of 20%R152a/80%RE170 using actual domestic water purifiers. This mixture is numbered and listed as R435A by ASHRAE recently. Test results show that the system performance with R435A is greatly influenced by the amount of charge due to the small internal volume of the refrigeration system of the domestic water purifiers. With the optimum amount of charge of 21 to 22 grams, about 50% of HFC134a, the energy consumption of R435A is 11.8% lower than that of HFC134a. The compressor discharge temperature of R435A $8^{\circ}C$ lower than that of HFC134a at the optimum charge. Overall, R435A, a new long term environmentally safe refrigerant, is a good alternative for HFC134a requiring little change in the refrigeration system of the domestic water purifiers.

HCFC22 대체 R290, R1270 및 R1270/R290, R290/HFC152a, R1270/R290/RE170 혼합냉매의 공기조화기와 열펌프 작동범위에서의 성능 평가 (Performance of HCFC22 Alternatives R1270, R290, R1270/R290, R290/HFC152a, R1270/R290/RE170 Refrigerants for Air-conditioning and Heat Pump Applications)

  • 황지환;백인철;정동수
    • 설비공학논문집
    • /
    • 제18권4호
    • /
    • pp.312-319
    • /
    • 2006
  • In this study, performance of 2 pure hydrocarbons and 7 mixtures was measured in an attempt to substitute HCFC22 used in air-conditioners and heat pumps. The mixtures were composed of R1270 (propylene), R290 (propane), HFC152a, and RE170 (Dimethyl ether, DME). The pure and mixed refrigerants tested have GWPs of $3{\sim}58$ as compared to that of $CO_2$ and the mixtures are all near-azeotropic showing the gliding temperature difference (GTD) of less than $0.6^{\circ}C$. Thermodynamic cycle analysis was carried out to determine the optimum compositions and actual tests were performed in a laboratory heat pump test bench at the evaporation and condensation temperatures of 7.5 and $45.1^{\circ}C$ respectively. Test results show that the coefficient of performance (COP) of these mixtures is up to 5.7% higher than that of HCFC22. While propane showed 11.5% reduction in capacity, most of the fluids tested had the similar capacity to that of HCFC22. Compressor discharge temperatures were reduced by $11{\sim}17^{\circ}C$ with these fluids. There was no problem with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of charge was reduced up to 55% as compared to HCFC22. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for. residential air-conditioning and heat pumping application.

설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
    • /
    • 제26권12호
    • /
    • pp.605-619
    • /
    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
    • /
    • 제27권7호
    • /
    • pp.380-394
    • /
    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

생마늘 및 흑마늘 열수추출 분말이 고콜레스테롤 혈증 흰쥐의 체내 지질조성에 미치는 영향 (Effects of Fresh and Black Garlic Hot Water Extract Powder on the Lipid Composition of Hypercholesterolemia Rats)

  • 강민정;신정연;이수정;신정혜
    • 생명과학회지
    • /
    • 제31권1호
    • /
    • pp.37-46
    • /
    • 2021
  • 생마늘 및 흑마늘 열수 추출물 각각을 동결건조하여 SD계 수컷 흰쥐를 정상식이 섭취군(NG), 고지방 콜레스테롤 섭취 대조군(CG), 고지방 콜레스테롤 식이에 1% 생마늘 열수추출 분말 혼합 급이군(FGEG), 고지방 콜레스테롤 식이에 1% 흑마늘 열수추출 분말 혼합 급이군(BGEG)으로 나누어 4주간 실험급이한 후 지질개선 효능을 조사하였다. 식이에 혼합한 생마늘 열수추출 분말(FGE) 및 흑마늘 열수추출 분말(BGE)의 총 페놀화합물 함량은 1319.99±10.46 mg/100 g이었고 S-allyl-cysteine (SAC) 함량은 FGE에 비해 16.3% 더 높았다. 혈청 총 지질, 총 콜레스테롤 및 중성지질 함량은 FGEG 및 BGEG에서 CG 보다 유의적으로 더 낮았다. HDL-콜레스테롤 함량은 CG 보다 FGEG 및 BGEG에서 유의적으로 더 높았고, LDL 및 VLDL-콜레스테롤 함량은 FGEG 및 BGEG가 더 낮았다. 혈청 ALT 및 AST 활성은 CG 보다 유의적으로 낮았으며, 특히 BGEG에서 더 낮았다. 간 조직의 총 지질 및 중성지질 함량은 BGEG에서 152.26 mg/g 및 64.59 mg/g으로 CG 보다 각각 36% 및 14.3% 더 낮았다. 혈청 및 간 조직에서의 TBARS 농도는 CG에 비해 유의적으로 낮았으며, FGEG와 BGEG 간에는 차이가 없었다. 이상의 결과로부터 마늘 추출분말의 지속적인 급이는 생체 내에서 지질농도의 감소, 과산화물질 생성억제 활성 및 항산화 활성은 증가하였으며 생마늘 보다는 흑마늘 열수추출 분말 급이군에서 더 효과적이었는데, 이러한 효과는 생마늘 보다 흑마늘에 총 페놀화합물이나 갈별물질 등 항산화 활성을 가지는 물질의 함량이 더 높기 때문으로 생각된다.