• 제목/요약/키워드: Cell temperature

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Evaluation of physiological functionalities of Codonopsis lanceolata root extracts on the storage temperatures and durations

  • Boo, Hee Ock;Park, Jeong Hun;Kim, Hag Hyun;Kwon, Soo Jeong;Lee, Moon Soon
    • 한국작물학회:학술대회논문집
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    • 한국작물학회 2017년도 9th Asian Crop Science Association conference
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    • pp.291-291
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    • 2017
  • The effects of bioactivity, binding polyphenolic contents, DPPH radical scavenging activity, ABTS radical scavenging activity, xanthine oxidase and immune activity on the storage temperature and durations of Codonopsis lanceolata root were evaluated in vitro. The contents of total polyphenol and flavonoid content by storage temperature and storage period was no significant difference according to the storage period, but it was found that the content was higher at lower storage temperature. The DPPH free radical scavenging activity at six different concentrations, 500, 1000, 2500, 5000, 10000 and 20000 mg/L are measured, the scavenging activity according to different storage temperature and storage period showed relatively the higher the activity in the shorter storage period or the lower storage temperature. The ABTS radical scavenging activity did not show a significant difference under various storage temperature and storage period conditions. The xanthine oxidase inhibitory activity of C. lanceolata extract tended to decrease more, depending on the longer storage period or the higher storage temperature. In different storage period and storage temperature conditions, the immune cell growth of C. lanceolata extract promoted a concentration-dependent manner in both human T cell and B cell, and did not show a significant difference. These results of this study suggested that the root of C. lanceolata may assist in the potential biological activities, and can be used as a source of human health products.

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냉기침강효과를 고려한 복잡지형의 최저기온 분포 추정 (Minimum Temperature Mapping in Complex Terrain Considering Cold Air Drainage)

  • 정유란;서형호;황규홍;황범석;윤진일
    • 한국농림기상학회지
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    • 제4권3호
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    • pp.133-140
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    • 2002
  • Site-specific minimum temperature forecasts are critical in a short-term decision making procedure for preventive measures as well as a long-term strategy such as site selection in fruits industry. Nocturnal cold air pools frequently termed in mountainous areas under anticyclonic systems are very dangerous to the flowering buds in spring over Korea, but the spatial resolution to detect them exceeds the current weather forecast scale. To supplement the insufficient spatial resolution of official forecasts, we developed a GIS - assisted frost risk assesment scheme for using in mountainous areas. Daily minimum temperature data were obtained from 6 sites located in a 2.1 by 2.1 km area with complex topography near the southern edge of Sobaek mountains during radiative cooling nights in spring 2001. A digital elevation model with a 10 m spatial resolution was prepared for the entire study area and the cold air inflow was simulated for each grid cell by counting the number of surrounding cells coming into the processing cell. Primitive temperature surfaces were prepared for the corresponding dates by interpolating the Korea Meteorological Administration's automated observational data with the lapse rate correction. The cell temperature values corresponding to the 6 observation sites were extracted from the primitive temperature surface, and subtracted from the observed values to obtain the estimation error. The errors were regressed to the flow accumulation at the corresponding cells, delineating a statistically significant relationship. When we applied this relationship to the primitive temperature surfaces of frost nights during April 2002, there was a good agreement with the observations, showing a feasibility of site-specific frost warning system development in mountainous areas.

PEMFC 고분자막의 어닐링 온도가 내구성에 미치는 영향 (Effect of Annealing Temperature on the Durability of PEMFC Polymer Membrane)

  • 이미화;오소형;박유준;유동근;박권필
    • Korean Chemical Engineering Research
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    • 제60권1호
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    • pp.7-11
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    • 2022
  • 고분자전해질 연료전지의(PEMFC)의 제막 과정에서 성능 및 내구성을 위해 건조와 어닐링의 열처리 과정이 필요하다. 본 연구에서는 고분자막 내구성 향상을 위한 최적의 어닐링 온도에 대해 연구하였다. 125~175 ℃ 온도 범위에서 어닐링하였고, 각 어닐링 온도에서 내구성의 기초 자료로 열 안정성 및 수소투과도를 측정하였다. 펜톤 반응과 OCV holding에 의해 전기화학적 내구성을 분석했다. 165 ℃ 어닐링 온도가 열 안정성과 수소투과도 면에서 최적의 온도였다. 펜톤 반응에서 165 ℃에서 어닐링한 막의 불소유출속도가 제일 낮고, OCV holding 실험에서도 165 ℃에서 어닐링한 막의 수명이 제일 길어, 165 ℃가 고분자막의 내구성을 위한 최적의 온도임을 확인했다.

고효율 후면 전극형 태양전지를 위한 나노 Paste의 적용에 대한 연구 (The application of Nano-paste for high efficiency back contact Solar cell)

  • 남동헌;이규일;박용환
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2010년도 추계학술대회 초록집
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    • pp.53.2-53.2
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    • 2010
  • In this study, we focused on our specialized electrode process for Si back-contact crystalline solar cell. It is different from other well-known back-contact cell process for thermal aspect and specialized process. In general, aluminum makes ohmic contact to the Si wafer and acts as a back surface reflector. And, silver is used for low series resistance metal grid lines. Aluminum was sputtered onto back side of wafer. Next, silver is directly patterned on the wafer by screen printing. The sputtered aluminum was removed by wet etching process after rear silver electrode was formed. In this process, the silver paste must have good printability, electrical property and adhesion strength, before and after the aluminum etching process. Silver paste also needs low temperature firing characteristics to reduce the thermal budget. So it was seriously collected by the products of several company of regarding low temperature firing (below $250^{\circ}C$) and aluminum etching endurance. First of all, silver pastes for etching selectivity were selected to evaluate as low temperature firing condition, electrical properties and adhesive strength. Using the nano- and micron-sized silver paste, so called hybrid type, made low temperature firing. So we could minimize the thermal budget in metallization process. Also the adhesion property greatly depended on the composition of paste, especially added resin and inorganic additives. In this paper, we will show that the metallization process of back-contact solar cell was realized as optimized nano-paste characteristics.

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Characterization of Methanol Crossover through Nafion Membranes by Direct Cell Performance Measurement

  • Park, Kyung-Won;Kim, Young-Min;Kwon, Bu-kil;Choi, Jong-Ho;Park, In-Su;Sung, Yung-Eun
    • 전기화학회지
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    • 제5권4호
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    • pp.226-231
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    • 2002
  • Power densities produced by the permeation of methanol through membranes were directly measured by inserting the membrane in front of anode in a membrane-electrode-assembly of a direct methanol fuel cell (DMFC). The power density was closely related to the loss of power in the DMFC and was strongly affected by temperature. As the cell temperature was increased, the power density resulting from methanol crossover was increased. The increase in methanol crossover had be attributed to diffusion caused or affected by temperature. Methanol crossover a major effect on the performance of a DMFC at a relatively low temperature with $26\%\;loss\;at\;30^{\circ}C$. In order to reduce methanol crossover, a conventional Nafion membrane was modified by the incorporation of Pt or Pd. The reduction in methanol crossover was investigated in these modified membranes by our cell performance measurement. Pt and Pd particles incorporated in the Nafion membranes block methanol pathway and prevent methanol transport through the membranes, which was proved by combining with liquid chromatography.

용융탄산염 연료전지에서 지지체를 사용한 얇은 연료극의 제작과 각기 다른 온도에서의 영향 (Fabrication and effect of different temperatures on the supported thin Anode for molten carbonate fuel cell)

  • 박동녘;;서동호;윤성필;설용건;한종희
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2010년도 추계학술대회 초록집
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    • pp.82.1-82.1
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    • 2010
  • Recently, Molten carbonate fuel cells(MCFCs) have been developing to get a good durability and economic feasibility for commercialization. To achieve these objectives, the cost of nickel based electrodes should be reduced. Regular anode thickness used in MCFCs is normally 0.7mm. Thus, in our study, the purpose was to reduce anode thickness up to 0.3 mm keeping MCFC performance on standard levels. In-situ sintering has been used, with 2 different fabrication methods (method A and B) and 2 different supports (support 1 and 2). Voltage losses at different temperature (600,620,640,$650^{\circ}C$) and after 1000 hours showed the higher performance that can be obtained using method B and support 2. After single cell test, an open-circuit voltage(OCV) of 1.075 V and a closed-circuit voltage(CCV) of 0.829V were obtained, at current density of $150mV/cm^2$. Also the voltage loss ratio at different cell temperature was lower in the case of method B and support 2. According to these results, the cost of anode fabrication can be reduced in the future, contributing for the economical feasibility of MCFCs.

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상온 상태에서 직접 메탄올 연료전지의 특성 연구 (The Study for Characteristic of Direct Methanol Fuel Cell in Ambient Temperature)

  • 윤효진;김정주;김동진
    • 한국산학기술학회논문지
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    • 제10권5호
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    • pp.955-961
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    • 2009
  • 현재 소형 휴대용 배터리의 용량 증가에 따라 배터리 부피가 커지는 문제를 가지고 있다. 이러한 문제를 해결하기 위해 직접 메탄올 연료전지가 대안으로 떠오르고 있다. 본 논문에서는 직접 메탄올 연료전지를 상온 상태에서 자연 대류 방식으로 공기를 공급하고, 메탄올의 농도와 유량의 변화에 대한 특성을 분석하였다. 분석 결과 저 농도의 메탄올에서는 수소 이온의 확산 속도 지연에 따른 분극현상이 발생하였고, 메탄올의 공급량이 높을수록 전지 Cell의 냉각 효과가 발생하여 출력이 감소한다.

신체냉각이 혈액세포성분 및 응혈기전에 미치는 영향에 관한 실험적 연구 (Hematologic and Coagulation Changes in Hypothermic Dogs)

  • 최대영
    • Journal of Chest Surgery
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    • 제2권1호
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    • pp.105-114
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    • 1969
  • This experiment was carried out to study the responses of cellular component of blood and bone marrow to cold and also the changes of coagulation during cooling. Forty-two mongrel dogs were subjected to hypothermia by ice-water surface cooling technique. Lowest body temperature ranged from 21-23 degree. Dogs were divided into 3 groups,Group I, 12 dogs: pentothal anesthesia for 3 hours, Group II, 20 dogs;hypothermic group and Group III,10 dogs;postsplenectomy hypothermic group. Results were summarized as follows: 1. Hemoglobin, hematocrit and red blood cell count significantly increased when animals were cooled, and increase was noted in similar magnitude among the animals of Group I. 2. White blood cell count extremely decreased after cooling and effect of splenectomy on white blood cell count was not apparent. No significant changes were seen among Group I. 3. Differential count of white blood cell when cooled showed relative increase of polymorphonuclear neutrophil and decrease of lymphocyte. 4. There was marked decrease of platelets when body temperature reached to 21-23degree and essentially. no changes was noted in Group I. 5. Clotting time, bleeding time, plasma prothrombin time, recalcification time, and fibrinolysis showed no significant changes when dogs were cooled. Clot retration and prothrombin consumption during hypothermia appeared to be poor. In Group II, bleeding time decreased after splenctomy and when body temperature was lowered, plasma prothrombin time, clot retraction, and prothrombin consumption decreased. Decreased bleeding time and poor clot retraction were noted in Group I. 6. It was found that megacaryocyte count decreased even though platelet count of peripheral blood markedly diminsished when animals were cooled. There was some tendency of erythroid hyperplasia noted during hypothermia.

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임피던스법을 적용한 연료전지의 성능평가 (Analysis on the Fuel Cell Performance by the Impedance Method)

  • 김귀열
    • 한국전기전자재료학회논문지
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    • 제20권10호
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    • pp.918-923
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    • 2007
  • Fuel cell is a modular, high efficient and environmentally energy conversion device, it has become a promising option to replace the conventional fossil fuel based electric power plants. The high temperature fuel cell has conspicuous feature and high potential in being used as an energy converter of various fuel to electricity and heat. Corrosions in molten electrolytes and the electric conductivity across the oxide scale have crucial characteristics. When molten salts are involved, high temperature corrosions become severe. In this sense, corrosions of alloys with molten carbonates have the most severe material problems. Systematic investigation on corrosion behavior of Fe/21Cr/Ti or Al alloy has been done in (62+38)mol% (Li+K)$CO_3$ melt at $650^{\circ}C$ using the electrochemical impedance spectroscopy method. It was found that the corrosion current of these Fe-based alloys decreased with increasing Al or Ti. And Al addition improved the corrosion resistance of this type of specimen and more improvement of corrosion resistance was observed at the specimen added with Al.

유동 해석을 이용한 평판형 고체 산화물 연료전지의 성능 특성 분석 (II) - 비등온 모델 - (Performance Predictions of the Planar-type Solid Oxide Fuel Cell with Computational Flow Analysis (II) - Non-isothermal Model -)

  • 현희철;손정락;이준식;노승탁
    • 대한기계학회논문집B
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    • 제27권7호
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    • pp.963-972
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    • 2003
  • Performance characteristics of the planar-type solid oxide fuel cell (SOFC) are investigated by the analysis of flow fields coupled with heat and mass transfer phenomena in anode and cathode channels. For these purposes, performance analysis of the SOFC is conducted based on electrochemical reaction phenomena in electrodes and electrolyte coupled with flow fields in anode and cathode channels. In the present study, the isothermal model adopted in the previous paper prepared by the same authors is extended to the non-isothermal model by solving energy equation additionally with momentum and mass transfer equations using CFD technique. It is found that the difference between isothermal and non-isothermal models come from non-uniform temperature distribution along anode and cathode electrodes by solving energy equation in non-isothermal model. Non-uniform temperature distribution in non-isothermal model contributes to the increase of average temperature of the fuel cell and influences its performance characteristics.