• 한국세라믹학회지
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• 제42권12호
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• pp.777-786
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• 2005

The Solid Oxide Fuel Cell (SOFC) is an electrochemical device to convert chemical energy of a fuel into electricity at temperatures from about 600 to $1000^{\circ}C$. The SOFC offers certain advantages over lower temperature fuel cells, notably its ability to use CO as a fuel rather than being poisoned by it, and high grade exhaust heat for combined heat and power, or combined cycle gas turbine applications. This paper reviews the operating principle, materials for different cell and stack components, cell designs, and applications of SOFCs. Among all designs of Solid Oxide Fuel Cells (SOFCs), the most progress has been achieved with the tubular design. However, the electrical resistance of tubular SOFCs is high, and specific power output $(W/cm^2)$ and volumetric power density $(W/cm^3)$ low. Planar SOFCs, in contrast, are capable of achieving very high power densities.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.121-124
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• 2007

Stacks of solid oxide fuel cell under 1kW max power were designed on planar type employing anode supported cell and metallic interconnects. The stacks composed of 3-cells, 8-cells, and 16-cells were fabricated by using single cell purchased from Indec, sealant and interconnect prepared at RIST. In performance test of the final 16-cells stacks, OCV was recorded to be 16.7 V. Peak power and power density were 1 kW, 0.77 $W/cm^{2}$ at $820^{\circ}C$, respectively. In addition, the long term degradation rate of the power exhibited 2.25 % in 500 h at $750^{\circ}C$.

• 대한기계학회논문집A
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• 제31권10호
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• pp.981-985
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• 2007

We present a MEMS-based portable Direct Methanol Fuel Cell (micro-DFMC), featured by a platinum sputtered microcolumn electrode and a built-in fuel chamber containing a limited amount of methanol fuel. Also presented is a micro-DMFC stack structure having a common electrolyte sandwiched by the microcolumn electrodes. The single cells with ME16 and PE16 electrodes show the maximum power densities of $31.04{\pm}0.29{\mu}W/cm^2$ and $9.75{\pm}0.29{\mu}W/cm^2$, respectively; thus indicating the microcolumn electrode (ME16) generates the power density (3.2 times) higher than the planar electrode (PE16). The single cell tests of ME16 and ME4 electrodes (Fig.8) show the maximum power of $31.04{\pm}0.29{\mu}W/cm^2$, and $25.23{\pm}2.7{\mu}W/cm^2$, respectively; thus demonstrating the increased window frame reduces the normalized standard power deviation (standard deviation over the average power). The normalized deviation of 0.11 in ME4 cell has been reduced to 0.01 in ME16 cell due to the increased window frames. The maximum power density of 4-cell stack is 15.7 times higher than that of the single cell. 4-cell stack produces the power capacity of 20.3mWh/g during 980min operation at the voltage of 450mV with the load resistance of $800{\Omega}$.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.361-364
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• 2009

KEPRI has studied planar type SOFC stacks using anode-supported single cells and kW class co-generation systems for residential power generation. A 1kW class SOFC system consisted of a hot box part, a cold BOP part and a water reservoir. A hot box part contains a SOFC stack made up of 48 cells with $10{\times}10cm^2$ area and ferritic stainless steel interconnectors, a fuel reformer, a catalytic combustor and heat exchangers. Thermal management and insulation system were especially designed for self-sustainable operation. A cold BOP part was composed of blowers, pumps, a water trap and system control units. When a 1kW class SOFC system was operated at $750^{\circ}C$ with hydrogen, the stack power was 1.2kW at 30 A and 1.6kW at 50A. Turning off an electric furnace, the SOFC system was operated using hydrogen and city gas without any external heat source. Under self-sustainable operation conditions, the stack power was about 1.3kW with hydrogen and 1.2kW with city gas respectively. The system also recuperated heat of about 1.1kW by making hot water. Recently KEPRI developed stacks using $15{\times}15cm^2$ cells and tested them. KEPRI will develop a 5 kW class CHP system using $15{\times}15cm^2$ stacks by 2010.

• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.384-389
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• 2009

KEPRI (Korea Electric Power Research Institute) has studied planar type solid oxide fuel cell (SOFC) stacks using anode-supported cells and kW class co-generation systems for residential power generation. In this work, a 1 kW SOFC system consisted of a hot box part, a cold BOP (balance of plant) part, and a hot water reservoir. The hot box part contained a SOFC stack made up of 48 cells, a fuel reformer, a catalytic combustor, and heat exchangers. Thermal management and insulation system were especially designed for self-sustainable operation in that system. A cold BOP part was composed of blowers, pumps, a water trap, and system control units. When the 1 kW SOFC stack was tested using hydrogen at $750^{\circ}C$, the stack power was about $1.2\;kW_e$ at 30 A and $1.6\;kW_e$ at 50 A. Turning off an electric furnace, the SOFC system was operated using hydrogen and city gas without any external heat source. Under self-sustainable operation conditions, the stack power was about $1.3\;kW_e$ with hydrogen and $1.2\;kW_e$ with city gas respectively. The system also recuperated heat of about $1.1\;kW_{th}$ by making hot water.

• 한국수소및신에너지학회논문집
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• 제20권4호
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• pp.300-308
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• 2009

In a pursuit of the development of alternative mobile power sources with a high energy density, a planar and air-breathing PEMFCs with a new type of hydrogen cartridge which uses onsite $H_2$ generated from sodium borohydride ($NaBH_4$) hydrolysis have been investigated for use in advanced power systems. Two types of $H_2$ generation through $NaBH_4$ hydrolysis are available: (1) using organic acids such as sulphuric acid, malic acid, and sodium hydrogen carbonate in aqueous solution with solid $NaBH_4$ and (2) using solid selected catalysts such as Pt, Ru, CoB into the stabilized alkaline $NaBH_4$ solution. It might therefore be relevant at this stage to evaluate the relative competitiveness of the two methods mentioned above. The effects of flow rate of stabilized $NaBH_4$ solution, MEA (Membrane Electrode Assembly) improvement, and type and flow control of the catalytic acidic solution have been studied and the cell performances of the planar, air-breathing PEMFCs using $NaBH_4$ has been measured from aspects of power density, fuel efficiency, energy density, and fast response of cell. In our experiments, planar, air-breathing PEMFCs using $NaBH_4$ achieved to maximum power density of 128mW/$cm^2$ at 0.7V and energy efficiency of 46% and has many advantages such as low operating temperature, sustained operation at a high power density, compactness, the potential for low cost and volume, long stack life, fast star-up and suitability for discontinuous operation.

• 한국수소및신에너지학회논문집
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• 제25권5호
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• pp.491-499
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• 2014

It is important to accurately measure and control the relative humidity of humidified gas entering a PEM (polymer electrolyte membrane) fuel cell stack because the level of humidification strongly affects the performance and durability of the stack. Humidity measurement devices can be used to directly measure the relative humidity, but they cost much to be equipped and occupy spaces in a fuel cell system. We present soft sensors for predicting the relative humidity without actual humidity measuring devices. By combining FIR (finite impulse response) model with PLS (partial least square) and SVM (support vector machine) regression models, DPLS (dynamic PLS) and DSVM (dynamic SVM) soft sensors were developed to correctly estimate the relative humidity of humidified gases exiting a planar-type membrane humidifier. The DSVM soft sensor showed a better prediction performance than the DPLS one because it is able to capture nonlinear correlations between the relative humidity and the input data of the soft sensors. Without actual humidity sensors, the soft sensors presented in this work can be used to monitor and control the humidity in operation of PEM fuel cell systems.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.21-24
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• 2008

We have developed a $kW_e$ class liquid fuel based solid oxide fuel cell (SOFC) system. Our final target is to develop the 1 $kW_e$ diesel based SOFC system for residential power generator(RPG). In this study, we present the conceptual design of SOFC system. System is composed of hot-box and cold-box. Planar typed SOFC stack, heat exchanger, combustor for stack tail gas, and fuel processor, such as fuel reformer and desulfurizer, are contained in the hot-box. And several balance of plants(BOP), such as fuel suppliers and controller, are contained in the cold-box. Before the SOFC system fabrication, we have already operated the selfsustaining fuel processor, and heat exchange of all heat-related components is simulated using ASPEN HYSYS, because heat maintenance and management in hot-box are important for stable operation of SOFC system. The self-sustained fuel processor was successfully operated for about 250 hours, and heat exchange is enough to operate the SOFC system.

• 대한기계학회논문집B
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• 제30권8호
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• pp.731-740
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• 2006

The solid oxide fuel cell (SOFC) is expected to be a candidate for distributed power sources in the next generation, due to its high efficiency and high-temperature waste heat utilization. In this study, the 5-cell SOFC stack was operated with pure hydrogen or reformed gas at anode side and air at cathode side. When stack was operated with diesel and methane ATR reformer, the influence of the $H_2O/C,\;O_2/C$ and GHSV on performance of stacks have been investigated. The result shows that the cell voltage was decreased with the increase of $H_2O/C$ and $O_2/C$ due to the partial pressure of fuel and water, and cell voltage was more sensitive to $O_2/C$ than $H_2O/C$. Next, the dynamic model of SOFC system included with ATR reformer was established and compared with experimental data. Based on dynamic model, the operation strategy to optimize SOFC-Reformer system was suggested and simulated.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.90-93
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• 2004

In this work, we have used different techniques for the surface passivation: conventional thermal oxidation (CTO), rapid thermal oxidation (RTO), and plasma-enhanced chemical vapour deposition (PECVD). The surface passivation qualities of eight different single and combined double layer have been investigated both on the phosphorus non-diffused p-type FZ silicon and on phosphorus diffused emitter of 100 ${\Omega}/Sq$ and 40 ${\Omega}/Sq$. In the single layer, silicon dioxide $(SiO_2)$ passivates good on the emitter while silicon nitride (SiN) passivates better than on the non-diffused surface. In the double layers, CTO/SiN1 passivates very well both on non-diffused surface on the emitter. However, RTO/SiN1 and RTO/SiN2 stacks are more suitable for surface passivation in solar cells caused by a relatively good passivation qualities and the low optical reflection. Applying these stacks in solar cells we achieved 18.5 % and 18.8 % on 0.5 ${\Omega}$ cm FZ-Si with planar and textured front surface, respectively. The excellent open circuit voltage $(V_{oc})$ of 675.6 mV is obtained the planar cell with RTO/SiN stack.