• 한국자기공명학회논문지
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• 제12권2호
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• pp.96-102
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• 2008

Direct quantification of methanol in polymer electrolyte membrane (PEM) by solid-state nuclear magnetic resonance (NMR) spectroscopy was studied and the methanol concentrations in PEM produced by crossover and diffusion were compared. The error range of the quantification was not smaller than ${\pm}15%$ and the amount of the methanol crossed over in our direct methanol fuel cells (DMFCs) was less than the methanol diffused to PEM. The methanol concentration in the PEM of the DMFC operated at different current densities were equivalent.

• 한국세라믹학회지
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• 제35권3호
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• pp.273-279
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• 1998

Unite cell of soid oxide fuel cell (SOFC) that consists of a dense yttria-stabilized zirconia(YSZ) electrolyte a porous nickel-YSZ cermet anode and a porous strontium- doped lanthanum manganate(LSM) cathod was fabricated from using pore former through co-firing technique. Initial sintering shrinkage rates of each layer were identified for fabricating SOFC. Heterogenous sintering was very effective in tailoring shrinkage rate for three layers. The powder tailoring necessary for shrinkage rate matching are as follows ; electrolyte of 60% TZ8YS/ 40% TZ8Y mixture anode of 51wt% NiO/49 wt% (70wt% TZ8YS/30 wt% UT ZrO2) mixture and cathode of 80% LSM/20% UT ZrO2 mixture . The overall sintering shrinkage rate differences of three layers using these compositions were maintained in a few percent.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.311-314
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• 2009

Recently by the development of the electronic engineering technology various mobile devices are developed. But their operation time need to be extended although capacity of the batteries are limited. We focused our attention to the portable SOFC system. Because SOFC has the high efficiency and a lot of strongness in comparison with other kinds of fuel cells, We evaluated hydrogen fed SOFC 50W system theoretically and got the results about the operating condition range from the comparison of the power efficiency, exhaust gas temperature, required heat for maintaining the operation temperature and operation time.

• 한국유체기계학회 논문집
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• 제11권1호
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• pp.33-39
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• 2008

Hybrid power generation systems combining a solid oxide fuel cell and a gas turbine is promising due to their high efficiency. In the pressurized hybrid system, the operating condition of the gas turbine may play a critical role in designing the hybrid system. In particular, prevention of surge of the compressor can be a critical issue. The existence of fuel cell between the compressor and the turbine may cause an additional pressure loss and thus compressor operating points tend to approach the surge if the original turbine inlet temperature is pursued. In this study, bypassing some of the turbine inlet gas directly to the turbine exit side is simulated. Its effects on suppressing the surge problem and change in performance characteristics are discussed.

• 한국세라믹학회지
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• 제43권11호
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• pp.746-750
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• 2006

NiO films and Ru co-sputtered NiO films were deposited by reactive magnetron sputtering for micro-solid oxide fuel cell anode applications. The deposited films were reduced to form porous films. The reduction kinetics of the Ru doped NiO film was more sluggish than that of the NiO film, and the resulting microstructure of the former exhibited finer pore networks. The possibility of using the films for the anodes of single chamber micro-SOFCs was investigated using an air/fuel mixed environment. It was found that the abrupt increase in the resistance is suppressed in the Ru co-sputtered film, as compared to undoped film.

• 한국세라믹학회지
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• 제53권5호
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• pp.469-477
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• 2016

The application of nanomaterials for electrodes of intermediate temperature solid oxide fuel cells (SOFC) is introduced. In conventional SOFCs, the operating temperature is higher than 1073 K, and so application of nanomaterials is not suitable because of the high degradation rate that results from sintering, aggregation, or reactions. However, by allowing a decrease of the operating temperature, nanomaterials are attracting much interest. In this review, nanocomposite films with columnar morphology, called double columnar or vertically aligned nanocomposites and prepared by pulsed laser ablation method, are introduced. For anodes, metal nano particles prepared by exsolution from perovskite lattice are also applied. By using dissolution and exsolution into and from the perovskite matrix, performed by changing $P_{O2}$ in the gas phase at each interval, recovery of the power density can be achieved by keeping the metal particle size small. Therefore, it is expected that the application of nanomaterials will become more popular in future SOFC development.

• Journal of Electrochemical Science and Technology
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• 제14권2호
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• pp.145-151
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• 2023

Planer-type electrolyte substrates are often utilized for stack manufacturing of electrolyte-supported solid oxide fuel cells (ES-SOFCs) to fulfill necessary requirements such as a high mechanical strength and redox stability. This work did an electrochemical analysis of ES-SOFC with different NiO-YSZ anode thicknesses to find the optimal value for the high performance of the fuel cell. The cell resistivities were constant at anode thickness between 25-58 ㎛, but a thick anode (74 ㎛) caused a high electrode resistivity leading to a dramatic reduction in cell performance. A stability test was performed for 50 hours at 700℃, and the results showed a degradation rate of 0.3% per 1000 h by extrapolated fitting.

• 전기화학회지
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• 제10권1호
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• pp.7-13
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• 2007

Glycine Nitrate Process(GNP)를 이용하여 $La_{0.75}Sr_{0.25}FeO_3$를 합성하였다. 이때, GNP의 글리신의 함량은 화학양론식으로 계산하여 3.17mol을 첨가하였다. ICP-AES분석으로 각각의 조성 함량을 조사하고, XRD, SEM분석으로 합성된 분말의 결정성과 입자크기를 분석하였다. 이렇게 분석한 분말은 일축가압 성형으로 펠렛을 제조하였으며, 이 시편은 $1200^{\circ}C$에서 소결하였다. 소결된 시편은 아르키메데스 법을 이용하여 소결밀도를 측정히였다. 전기화학적 성능을 평가하기 위해 AC impedance spectroscopy로 측정하였으며, GNP 법으로 합성된 LSF가 기존의 LSM 보다 낮은 Ohmic resistance및 Polarization resistance를 보임을 확인하였다. 또한 합성된 LSF를 양극으로 사용하여 연료극 지지체식 고체산화물 연료전지의 단위전지를 제작하였으며, 그 성능은 $750^{\circ}C$에서 $342mW/cm^2(0.7V,\;488mA/cm^2)$을 나타내었다. 마지막으로 임피던스 분석에 의하여 단위전지의 전기화학적 분극저항을 평가하였다.

• 유기물자원화
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• 제25권1호
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• pp.23-33
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• 2017

본 연구에서는, 높은 함수율을 가진 음식물류 폐기물을 Bio-dying 공법을 이용하여 처리하였을 때 수분과 유기물의 변화정도를 분석하였으며 음식물류 폐기물 처리 시 온도와 염도가 Bio-dying 공법의 운전특성에 미치는 영향을 평가하였다. 또한, Bio-drying 후 분해산물의 SRF(Solid Refuse Fuel)로서의 가치 평가를 위한 펠렛 제조의 최적조건 도출 및 SRF의 발열량 분석을 통한 고형연료로서의 가치를 평가하였다. 그 결과, 1일 투입량에 따른 온도, $CO_2$ 농도, 유기물 제거율과 무게 감소율 값을 분석하였다. 유기물 제거율과 무게 감소율은 투입량 2.4 kg/day에서 각각 86%, 68%로 최대값을 나타내었다. 이를 통해 최적 음식물류 폐기물 투입량은 2.4 kg/day라 판단되었다. 펠렛 성형 결과, 원료 함수율이 10~25% 이내에서 펠렛 제조가 가능하고, 외형유지와 강도면에서 가장 좋은 품질결과를 보여준 함수율 25%가 가장 적합하다고 판단되었다. Bio-drying 후 분해산물의 SRF 고위발열량은 3,500 kcal/kg 이상의 값을 나타내었다.

• Nuclear Engineering and Technology
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• 제24권1호
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• pp.40-51
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• 1992

연구용 원자로의 분산형 핵연료에 대한 노내 조사 거동의 주요 특성중의 하나는 핵연료심 팽윤에 기인된 핵연료봉 직경 증가이다. 본 논문에서는 분산형 우라늄실리사이드 핵연료에 대한 노내 조사거 동과 실험 증거들을 분석함으로써 그 핵연료의 팽윤에 대한 물리적 해석 모형인, DFSWELL 전산 모형을 개발하였다. 문헌에 보고된 실험 증거들로부터 노내에서 U$_3$Si-Al 핵연료심의 부피변화는 온도와 핵분열율에 따라 크게 영향을 받는 것으로 나타났다. 분산형 우라늄 실리사이드 핵연료에 대한 정량적 팽윤량은 주어진 온도, 핵분열율, 핵분열고체생성물 측적 및 핵분열기체 기포거동을 고려함으로써 평가될 수 있다. 연구로의 분산형 우라늄실리사이드 핵연료의 팽윤 현상은 다음과 같은 세 가지 현상으로 귀결된다. i ) 핵분열기체생성물 기포 생성/축적에 치한 부피변화 ii ) 고체 핵분열생성물의 축적 및 상 변화에 의한 부피변화 iii ) 핵연료 입자와 기지 사이의 공유층에 대한 부피변화 상기 세 가지의 물리 적 현상을 고려하는 본 DFSWELL 전산 모형의 출력이력 조건에 따른 절대 예측치들은 실행 결과와 비교할 때 분산형 우라윰실리 사이드 핵연료의 조사추 팽윤 실측치와 잘 일치한다.