• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.110-112
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• 2006

Membrane electrode assembly (MEA) for polymer electrolyte fuel cell (PEFC) are commonly prepared in the research laboratory by spraying, screen-printing and brushing catalyst slurry onto membrane or other support material like carbon paper or polyimide film in a batch style. These hand applications of the catalyst slurry are painstaking process with respect to precision of catalyst loading and reproducibility. It has been generally mentioned that the adoption of continuous process is very helpful to develop the reliable product. In the present work, we report the results of using continuous type coater with doctor-blade to coat catalyst slurry for preparing the MEA catalyst layers In a faster and highly reproducible fashion. We show that while expectedly faster than batch style, the machine coater requires the use of slurry of appropriate composition and a properly selected transfer decal material in order to achieve superior MEA plat lnw loading reproducibility. To make highly viscous catalyst slurry that is imperative for using coater, we use 40wt.% Nafion solution and minimize the content of organic solvent. And the choice of proper high surface area catalyst is important in the viewpoint of making well-dispersed slurry. After catalyst coating onto the support material, we transferred the catalyst layer to both sides of Nafion membrane by hot-pressing In this case, the degree of transfer was Influenced by hot-pressing condition including temperature, pressure, and time. To compare the transferring ability, we compared so many films and detaching papers. And among the support, polyethylene terephthalate(PET) film shows the prominent result.

• 한국응용과학기술학회지
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• 제34권4호
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• pp.818-826
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• 2017

신 재생에너지 보급통계에 의하면 바이오매스 발전실적은 2013년 부터 급증하고 있으며 그 중에서 가장 급격하게 증가한 연료는 Wood pellet으로 2013년 696Gwh, 2014년 2,764Gwh, 2015년에는 2,512Gwh를 발전 하였고 국내 Wood pellet 총 소비량은 2015년 기준 148만톤이며 그 중 발전용으로 소비된 Wood pellet은 108만톤으로 약 73%를 차지하고 있다. 본 연구에서 Wood pellet 소요량을 예측한 결과 국내 발전용으로 필요한 Wood pellet 소요량은 2020년 261만톤, 2025년 685만톤, 2030년 1,139만톤이 필요하며, 최적 바이오매스 발전량 산정을 위하여 바이오매스 발전소에서 국내 생산 Wood pellet 사용량을 50% 사용한다는 가정하에 기 허가 신청된 발전소를 가동하기 위해서는 2021년 226만톤의 Wood pellet이 국내에서 생산되어야 한다는 결론이 도출 되었다.

• 디지털융복합연구
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• 제17권10호
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• pp.103-113
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• 2019

본 논문은 한국에서의 석탄산업이 신기후체제의 출범 이후에도 여전히 중요하며, 일정한 물량의 석탄 비축을 통해 에너지원의 수급을 조절할 수 있는 능력을 지닐 필요성에 대한 근거를 제시하는데 있다. 최근 신재생에너지의 비중 증가는 석탄이나 석유와 같은 화석연료의 의존도를 낮출 것으로 전망된다. 그리고 이에 따라 석탄의 사용도 감소할 것으로 전망되지만, 아직 에너지원별 수요의 면에서나 전력 공급의 면에서 석탄이 에너지원으로서의 지위가 여전히 큰 것이 확인되었다. 석탄의 최적 비축 규모는 기존 연구의 연간 수요를 기준으로 추정하였다. 이러한 점에서 지속가능한 성장을 위한 산업적 정책으로서 석탄산업의 유지와 연간 최적 비축 규모의 결정은 매우 중요한 문제이다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.137-142
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• 2008

액체로켓엔진 재생냉각 연소기에서 산화제 선공급 cyclogram시의 점화 특성에 대해 기술하였다. 연소기의 연소압력은 60 bar, 추진제 유량은 약 89 kg/s 그리고 노즐 팽창비는 12이다. 산화제 선공급 cyclogram을 위해 수행한 연소기로의 연료 및 산화제 수류시험, 산화제 선공급에 따른 점화기 작동성 확인을 위한 점화시험, 연소기의 주 점화 및 연소 확인을 위한 저압 연소시험 그리고 설계점에서 연소기 작동성/연소 안정성 및 연소성능/재생냉각 성능 확인을 위한 연소시험 등에 대해 기술하였다. 산화제 선공급 점화 및 연소시험은 성공적으로 이루어졌으며 연소기에 대한 안정적인 점화 cyclogram을 개발하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.665-667
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• 2016

최근 화석연료의 고갈 및 환경문제로 인해 신재생 에너지에 대한 관심이 해마다 증가하고 있다. 신재생에너지는 깨끗하고 재사용이 가능한 에너지원으로 풍력과 태양광을 이용한 방법이 대표적이다. 이들 중 풍력 발전시스템은 자연의 바람을 이용하여 바람의 운동에너지를 전기에너지로 변환하는 방식이다. 기존에는 풍력 발전시스템을 구현하여 풍동실험을 하기 위해 실제 풍력과 유사한 환경을 구성하여 풍동실험을 하였다. 하지만, 이러한 풍동실험을 구성하기에는 비용이 커지는 문제가 발생한다. 본 논문에서는 이러한 풍동실험을 모터와 발전기를 이용한 테스트 베드를 구성하여 실험할 때 실제 풍동실험에서 발전기의 특성을 고려하여 모터를 제어함으로서 풍동실험과 유사한 결과를 얻고자한다.

• 신재생에너지
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• 제18권2호
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• pp.40-49
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• 2022

In this study, the phase and electrochemical properties of Co and Ti substituted layered perovskites SmBaCo_2-xTi_xO_5+d (x=0.5, 0.7, 1.0, 1.1, 1.3, and 1.5) were analyzed, and their application as electrodes in solid oxide fuel cells (SOFCs) were evaluated. After calcination at 1300℃ for 6 h, a single phase was observed for two compositions of the SmBaCo_2-xTi_xO_5+d oxide system, SmBaCoTiO_5+d (x=1.0) and SmBaCo_0.9Ti_1.1O_5+d (x=1.1). However, the phases of SmBaCoTiO_5+d (SBCTO) and SmTiO₃ coexisted for compositions with x≥1.3 (Ti content). In contrast, for compositions of x≤0.7, the SmBaCo₂O_5+d phase was observed instead of the SmTiO₃ phase. To evaluate the applicability of these materials as SOFC electrodes, the electrical conductivities were measured under various atmospheres (air, N₂, and H₂). SBCTO exhibited stable semi-conductor electrical conductivity behavior in an air and N₂ atmosphere. However, SBCTO showed insulator behavior at temperatures above 600℃ in a H₂ atmosphere. Therefore, SBCTO may only be used as cathode materials. Moreover, SBCTO had an area specific resistance (ASR) value of 0.140 Ω·cm² at 750℃.

• 신재생에너지
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• 제17권2호
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• pp.50-58
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• 2021

We proposed an MEA development methodology that accurately measures intrinsic MEA performance while considering the uneven reaction environments formed inside a large-area BP. To facilitate measurement of the inherent MEA performance, we miniaturized the active area of the MEA to 3 cm², and prepared two MEAs with different ionomer contents of 0.65 and 0.80 (I/C). By simulating the operating conditions of a 100 cm² BP at the inlet (I), center (C), and outlet (O), the oxygen concentration and relative humidity were determined to be 20.7, 13.8, 11.7%, and 50, 66.1, and 70.1% respectively. We measured the performance and electrochemical analysis of the prepared MEAs under the three simulated conditions. Based on the results of statistical analysis of the evaluated MEA performance data, I/C 0.65 MEA had a higher average performance and lower performance deviation than I/C 0.80 MEA. Hence, it can be concluded that an I/C 0.65 MEA is a more effective MEA for large-area BP. Based on the above research process, we confirmed the effectiveness of the proposed MEA development methodology.

• 신재생에너지
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• 제18권2호
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• pp.1-8
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• 2022

This study aimed to determine the optimal conditions for fabricating pitch pine (PCP) and Mongolian oak (MOK) pellets using chestnut-shell tea waste (CSW) and castor oil (CSO) as additives. For pellets fabricated using a pilot-scale flat-die pellet mill, all moisture content (MC) was in line with A1 wood pellet standards for residential and small-scale commercial uses designated by the National Institute of Forest Science at the Republic of Korea (NIFOS), regardless of fabricating conditions; the durability of PCP pellets prepared using PCP particles with 10% MC, and CSW addition also satisfied these criteria. The moisture tolerance of PCP pellets improved with combination of 2 wt% CSW and 2-6 wt% CSO. Overall, use of 20 mesh CSW as an additive, PCP with 10% MC, and MOK with 12% MC was found to be optimal. Moreover, using CSO as an additive, high-quality PCP and MOK pellets can be fabricated by adjusting the particles to 12% MC. However, the durability of PCP and MOK pellets prepared using these conditions did not meet the wood pellet standards for residential and small-scale commercial use. Therefore, further research is needed to improve the durability of these pellets.

• 신재생에너지
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• 제18권3호
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• pp.23-31
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• 2022

This study evaluated the potential of coffee waste (CW) and used frying oil (UFO) as an additive in the production of pitch pine (PIP) and Mongolian oak (MOK) pellets. Ash contents obtained from CW and UFO were 0.5% and <0.1%, respectively. The calorific values of UFO (31.4 MJ/kg) and CW (26.3 MJ/kg) are higher than PIP (20.6 MJ/kg) and MOK (19.1 MJ/kg). For pellets fabricated using a pilot-scale flat-die pellet mill, regardless of fabricating conditions, moisture content (MC) and bulk density of PIP and MOK pellets satisfied the A1 wood pellet standard for residential and small-scale commercial uses, as designated by the National Institute of Forest Science (NIFOS) of the Republic of Korea. When CW was used as an additive, durability of PIP pellets made with 12%-MC sawdust and MOK pellets increased. The optimal conditions for producing PIP and MOK pellets could be by adding 20 mesh CW as an additive and the using of 12%-MC sawdust. However, durability of PIP pellets and ash content MOK pellets did not satisfy the A1 wood pellet standard of NIFOS. Thus, further research is needed to improve the properties of wood pellets with additives.

• 신재생에너지
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• 제18권3호
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• pp.1-9
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• 2022

This study analyzed the anticipated supply-and-demand of forest biomass energy (through wood pellets) until 2050, in South Korea. Comparing the utilization rates of forest resources of five countries (United Kingdom, Germany, Finland, Japan, and S. Korea), it was found that S. Korea does not nearly utilize its forest resources for energy purposes. The total demand for wood pellets in S. Korea (based on a power generation efficiency of 38%) was predicted to be 3,629 and 4,371 thousand tons in 2034 and 2050, respectively. The anticipated total wood pellet power generation ratio to target power consumption is 1.13% (5,745 GWh), 1.17% (6,336 GWh), and 1.25% (7,631 GWh) in 2020, 2030, and 2050, respectively. Low value-added forest residues left unattended in forests are called "Unused Forest Biomass" in S. Korea. From the analysis, the total annual potential amount of raw material, sustainably collectible amount, and available amount of wood pellet in 2050 were estimated to be 6,877, 4,814, and 3,370 thousand tons, respectively. The rate of contribution to Nationally Determined Contributions was up to 0.64%. Through this study, the authors found that forest biomass energy will contribute to a carbon neutral society in the near future at the national level.