http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Preparation of Nafion/polystyrene composite membranes using supercritical CO2 impregnation for DMFCs
변정연,석준호,김화용 한국화학공학회 2007 화학공학의이론과응용 Vol.10 No.1
Grafting of styrene onto Nafion membranes was carried out by the impregnation and radical polymerization in the supercritical carbon dioxide (scCO2) as a solvent and swelling agent. In impregnation process, Certain amounts of CO2 charged into the apparatus until desired pressure was reached. Styrene monomer and the initiator 2,2``-Azoisobutyronitrile (AIBN) were impregnated into Nafion membranes at 38℃ for 4h. After releasing CO2, the polymerization step then was started by raising the temperature 80℃ and carried out at a pressure of 100bar for 4h. After grafting reaction, the grafted membranes have been sulfonated to various degrees in concentrated sulfuric acid (98%H2SO4) at room temperature. The grafted membranes were characterized by measuring their ion exchange capacities (IEC), ion conductivity and methanol permeation. The structure and morphology of these membranes were observed with FTIR and SEM. The N-g-pssa showed lower methanol permeability than that of Nafion 115. As the IEC and ion conductivity were increased, the cell performance was simultaneously increased. The grafted membranes(N-g-pssa) were tested as electrolytes in the DMFC station.
연료전지의 자가 가습 Pt/TiO₂/Nafion 전해질막의 제조
변정연(Byun, Jung-Yeon),김효원(Kim, Hyo-Won),주민철(Ju, Min-Cheol),김화용(Kim, Hwang-Yong) 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.11
A novel self-humidifying composite membrane for the proton exchange membrane fuel cell (PEMFC) at low humidity condition was developed. The Pt/TiO₂ catalyst particles were synthesized via supercritical impregnation methods. Pt precursor was dissolved in supercritical carbon dioxide and impregnated onto TiO₂ particles. Pt precursors were platinum(II) acetylacetonate, Dimethyl(1,5-cyclooctadiene) platinum(II) and we controlled the ratio of Pt to TiO₂ The impregnated Pt precursor was converted to TiO₂ supported Pt nanoparticle under various reducing conditions. TiO₂ catalyst particles were dispersed uniformly into the Nafion solution, and then Pt/TiO₂/Nafioncomposite membrane was prepared using solution-cast method. The size, dispersion and content of the platinum had been characterized with Transmission Electron Micrograph (TEM), X-ray diffract ion (XRD) and Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP-AES). The cell performance with the self-humidifying composite membrane was compared with a recast Nafion membrane under both humidified and dry conditions at 65 ?C.
변정연 ( Jung Yeon Byun ),이우균 ( Woo Kyun Lee ),최성호 ( Sung Ho Choi ),오수현 ( Su Hyun Oh ),유성진 ( Seong Jin Yoo ),권태성 ( Tae Sung Kwon ),성주한 ( Joo Han Sung ),우재욱 ( Jae Wook Woo ) 대한원격탐사학회 2012 大韓遠隔探査學會誌 Vol.28 No.1
본 연구의 목적은 산림생태계 분포 모델인 Hy TAG모델(Hydrological and Thermal Analogy Group)과 기능 모델인 MC1 모델(MAPSS-CENTURY 1) 그리고 사회·환경적 지표를 이용하여 기후변화가 한반도 산림생태계에 미치는 영향을 파악하는 것이다. Hy TAG의 식생유형분포 변화 빈도와 방향으로부터 산림식생의 민감성과 적응성을 정량화하였다. 또한 MC1으로부터 추정되는 순일차 생산량 및 토양탄소 저장량의 변이 및 경향으로부터 산림기능의 민감성과 적응성을 정량화하였다. 사회·환경적 지표로는 재정자주도 또는 산림관련 공무원 수 등과 같은 통계자료를 포함하였다. 모든 지표들을 정규화하고 취약성 평가식에 적용하여 취약성 결과를 도출하였다. 취약성 평가의 시간적 범위는 현재(1971-2000)와 미래(2021-2050)로 구분하였다. 국가 기후변화 정책의 우선순위를 판단하기 위해 지표 별 공간 분포 지도를 작성하고 행정구역간의 취약성을 비교한 결과, 지역별로 취약성의 차이가 있는 것으로 나타났다. 이러한 취약성 차이는 적응능력에 따라 가장 크게 좌우되는 것으로 판단되었다. 본 연구의 취약성 평가 방법 및 결과는 산림 경영적 측면에서 의사결정 시스템 개발과 기후변화에 대한 적응정책 수립의 판단 자료로 활용될 것이다. The purpose of this study was to assess the vulnerability of forest ecosystem to climate change in South Korea using socio-environmental indicators and the results of two vegetation models named as Hydrological and Thermal Analogy Group (Hy TAG), and MAPSS-Century 1(MC1). The changing frequency and direction of biome types estimated by Hy TAG model was used for quantifying sensitivity and adaptive capacity of forest distribution. Similarly, the variation and changing tendency of net primary production and soil carbon storage estimated by MC1 model was used for quantifying sensitivity and adaptive capacity of forest function. As socio-environmental indicators, many statistical data such as financial autonomy rate and the number of forestry officer was prepared. All indicators were standardized, and then calculated using the vulnerability assessment equation. The period of vulnerability assessment was divided into the past(1971-2000) and the future(2021-2050). To understand what policy has a priority to climate change, distribution maps of each indicators was depicted and the vulnerability results were compared among administrative districts. Evident differences could be found in entire study area. These differences were mostly derived from regional specific adaptive capacity. The result and methodology of this study would be helpful for the development of decision-making supporting system and policy making in forest management with respect to climate change.
TiO₂ 촉매를 첨가한 자가 가습 연료전지용 MEA의 제조
변정연(Byun, Jung-Yeon),이용진(Lee, Yong-Jin),주민철(Ju, Min-Cheol),김화용(Kim, Hwa-Yong) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.05
A novel self-humidifying composite membrane for the proton exchange membrane fuel cell (PEMFC) at low humidity condition was developed. The Pt/TiO₂ catalyst particles were synthesized via supercritical impregnation methods. Pt precursor was dissolved in supercritical carbon dioxide and impregnated onto TiO₂ particles. Pt precursors were platinum(II) acetylacetonate, Dimethyl(1,5-cyclooctadiene) platinum(II) and we controlled the ratio of Pt to TiO₂. The impregnated Pt precursor was converted to TiO₂ supported Pt nanoparticle under various reducing conditions. Pt/TiO₂ catalyst particles were dispersed uniformly into the Nafion solution, and then Pt/TiO₂/Nafion composite membrane was prepared using solution-cast method. The self-humidifying composite membrane could minimize membrane conductivity loss under dry conditions due to the presence of catalyst and hydrophilic Pt/TiO₂ particles. To optimize the performance of MEA, amount of ionomer loading was controlled. And mixed catalysts were used. The cell performance of MEA was obviously improved under dry conditions at 65?C.
초임계유체를 이용한 PEMFC용 자가 가습 백금/나피온 막의 제조
김화용,변정연,김효원,성준용 한국청정기술학회 2007 청정기술 Vol.13 No.2
Pt/Nafion self-humidifying membranes for Polymer Electrolyte Membrane Fuel Cell (PEMFC) were synthesized via a supercritical-impregnation method. The Nafion 112 membranes were impregnated with Pt(II) acetylacetonate from a supercritical carbon dioxide (scCO2) solution at 80℃ and 19.8 MPa. After the impregnation, the Pt-impregnated Nafion membrane was converted Pt deposited Nafion(Pt/Nafion) membrane by reducing agent, sodium borohydride (NaBH4) under 50℃ and 2 hours. The prepared Pt/Nafion membranes were investigated by SEM, EDS and EPMA. The performance of the Pt/Nafion membranes was examined in PEMFC as a self-humidifying membrane. The cell performance of the Pt/Nafion membrane at 65℃ is better than that of Nafion 112. 초임계함침법을 이용하여 백금을 나피온 112 막에 함침시켜 자가가습 막을 제조하였다. 초임계이산화탄소를 용매로 하여 나피온112 막에 Pt(II)(acac)2를 80℃, 19.8 MPa 조건에서 함침하고, 함침 이후 이를 NaBH4 용액을 사용하여 50℃ 에서 2시간 동안의 환원과정을 통하여 Pt 입자로 환원시켜 PEMFC용 백금/나피온 자가-가습 전해질막을 제조하였다. 제조한 백금/나피온 막들을 SEM, EDS, EPMA 등의 분석을 통하여 백금 입자들이 균일하게 분산되어 함침되었음을 확인하였다. 제작한 백금/나피온 막을 무가습 조건에서 구동되는 고분자 전해질 연료전지(PEMFC)의 전해질로 적용하였을 때 65 ℃ 구동온도에서 일반적인 나피온 112를 전해질로 사용한 경우보다 향상된 성능을 보였다.