• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.05a
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• pp.9-9
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• 2009

Coated conductor is required to have good critical current property for high efficiency of electric power applications. Until now, long coated conductor does not show high Jc over 3 MA/$cm^2$ in thick superconducting layer because of texture degradation by thick superconducting layer. In this study, in order to overcome this issue, thicker superconducting layer was deposited with optimized conditions to reduce the degradation of critical current density. SmBCO superconducting coated conductor was deposited with 1~3 um of thickness at $750\sim850^{\circ}C$ under 15~20 mTorr of oxygen partial pressure using batch type EDDC( evaporation using drum in dual chamber). The buffered substrate for superconducting layer deposition was used IBAD-MgO template with the architecture of $LaMnO_3/MgO/Y_2O_3/Al_2O_3$/Hastelloy. After fabrication of coated conductor, critical current was measured by 4-prove method under self-magnetic field and 77K. In addition, surface morphology and texture were analyzed by SEM and XRD, respectively. 3 um thick SmBCO coated conductor shows highest $I_C$ values of 638A/cm-w in 1 m long in the world.

• Journal of the Korean Applied Science and Technology
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• v.24 no.3
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• pp.272-277
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• 2007

Catalytic activity changes of perovskite catalysts were examined with their A-site substitution. For the preparation of catalysts, Mn was used for B-site component and La, Ce, Sr, Ba, Ca, Ag were used for A-site component of the perovskite $catalysts(ABO_3)$ The effect of calcination temperature on methane combustion and perovskite structure was also investigated. The surface area and adsorbed oxygen species were tested with BET apparatus and $O_2-TPD$, respectively. Perovskite catalysts whose A-site was partially substituted needed higher calcination temperature than un-substituted one to form the perovskite structure. From $O_2-TPD$ experiment, it was found that methane combustion activity was directly related to the oxygen desorbing ability of the catalysts. The prepared catalyst(LM-7) was stable at $600^{\circ}C$ for 72 hours of reaction.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.129-132
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• 2007

Advanced structure of metal-supported solid oxide fuel cells was devised to overcome sealing problem and mechanical instability in ceramic-supported solid oxide fuel cells. STS430 whose dimensions were 26mm diameter, 1mm thickness and 0.4mm channel width was used as metal support. Thin ceramic layer composed of anode(Ni/YSZ) and electrolyte(YSZ) was joined with STS430 metal support by using a cermet adhesive. $La_{0.8}Sr_{0.2}Co_{0.4}Mn_{0.6}O_{3}$ perovskite oxide was used as cathode material. It was noted that oxygen reduction reaction of cathode governed the overall cell performance from oxygen partial pressure dependance.

• 한국전기화학회:학술대회논문집
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• 2004.06a
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• pp.297-302
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• 2004

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.112.2-112.2
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• 2008

• Korean Journal of Materials Research
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• v.17 no.6
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• pp.313-317
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• 2007

In-situ micro-channeled multi tubular solid oxide fuel cell(SOFC) was fabricated using multi-pass extrusion process with out side diameter of 2.7 mm and active length of 5 mm that contained 61 individual cells. Cell materials used in this work were NiO-YSZ (50 : 50 vol.%), 8 mol% yttria-stabilized zirconia(8YSZ), $La_{0.8}Sr_{0.2}MnO_3(LSM)$ as anode, electrolyte, and cathode, respectively. The arrangement of each electrode and electrolyte layer in green bodies showed uniformity and integrity after extrusion and sintering. The XRD analysis confirmed that no reaction phases appeared and the microstructure of the electrolyte was fairly dense (relative density > 96%) after sintering.

• Journal of the Korean Electrochemical Society
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• v.13 no.4
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• pp.256-263
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• 2010

A Crofer 22 APU mesh coated with a conductive ceramic material was developed as an alternative cathode current collector to Ag-based materials for solid oxide fuel cells. $(La_{0.80}Sr_{0.20})_{0.98}MnO_3$ (LSM) layer was deposited onto the Crofer mesh using a spray-coating technique, in an attempt to mitigate the degradation of electrical properties due to surface oxidation at high temperatures. The oxidation experiments at $800^{\circ}C$ in air indicated that the areaspecific resistance (ASR) of the LSM-coated Crofer mesh was strongly dependent on the wire diameter and the contact morphology between mesh and cell. In addition, the post-heat-treatment in $H_2/N_2$ resulted in a reduced thickness of Cr-containing oxide scales at the interface between Crofer mesh and LSM layer, leading to a decreased ASR.

• Journal of Energy Engineering
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• v.29 no.2
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• pp.1-9
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• 2020

In recent days, fuel cell has received attention from the world as an alternative power source to hydrocarbon used in automobile engines. With the industrial advances of fuel cell, There have been a lot of researches actively conducted to find a way of generating hydrogen. Among many hydrogen production methods, Solid Oxide Electrolysis Cell(SOEC) is not only a basic way but also environment-friendly method to produce hydrogen gas. Solid Oxide Electrolysis Cell has lower electrical energy demands and high thermal efficiency since it is possible to operate under high temperature and high pressure conditions. For these reasons, experimental researches as well as studies on numerical modeling for Solid Oxide Electrolysis Cell have been under way. However, studies on numerical modeling are relatively less enough than experimental accomplishments and have limited performance prediction, which mostly is considered as a result from inadequate effects of electrochemical properties by temperature and pressure. In this study, various experimental studies of commercial Membrane Electrode Assembly (MEA) composed of Ni-YSZ (40wt%, Ni-60 wt% YSZ)/8-YSZ (TOSOH, TZ8Y)/LSM (La_0.9Sr_0.1MnO₃) was utilized for improving effectiveness of SOEC model. After numerically analyzing effects of electrochemical properties according to operating temperature, causing the largest deviation between experiments and simulation are that Charge Transfer Coefficient (CTC), exchange current density, diffusion coefficient, electrical conductivity in SOEC. Analyzing temperature effect on parameter used in overpotential model is conducted for modeling of SOEC. cross-validation method is adopted for application of various MEA and evaluating feasibility of model. As a result, the study confirm that the numerical model of SOEC based on structured process of effectiveness evaluation makes performance prediction better.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1075-1082
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• 1999

Composite air electrodes of 50/50 vol% LSM- YSZ where LSM =$\textrm{La}_{1-x}\textrm{Sr}_{x}\textrm{MnO}_{3}$(0$\leq$x$\leq$0.5) were prepared by colloidal deposition technique. The electrodes were then examined by scanning electron microscopy (SEM) and studied by ac impedance spectroscopy in order to improve the performance of a solid oxide fuel cell (SOFC). Reproducible impedance spectra were confirmed by using the improved cell, consisting of LSM- YSZ/YSZ/LSM-YSZ. These spectra were a strong function of operating temperature and the stable conditions for the cells were typically reached at $900^{\circ}C$. The typical spectra measured for an air//air cell at $900^{\circ}C$ were composed of two arcs. Addition of YSZ to the LSM electrode led to a pronounced decrease in cathodic resistivity of LSM-YSZ composite electrodes. Polishing the electrolyte surface to eliminate the influences of surface impurities could further reduce cathode resistivity. The cathodic resistivity of the LSM-YSZ electrodes with catalytic interlayer (Ni or Sr) was much smaller than that of LSM-YSZ electrodes without catalytic interlayer. In addition, the cathodic resistivity of the LSM-YSZ electrodes was a strong function of composition of electrode materials, the electrolyte geometry, and applied current.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.05a
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• pp.1-2
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• 2009

The high critical current ($I_c$, A) of SmBCO coated conductor in a magnetic field, the high production rate and the high material yield are promising for applications. The inhomogeneity of Ie at the long length coated conduct is very important problem for electric application. So we researched the reason of inhomogeneity of $I_c$ at long length tape prepared by batch type co-evaporation system called by EDDC. The long length SmBCO coated conductors were developed on $LaMnO_3/IBAD-MgO/Y_2O_3/Al_2O_3$/Hastelloy C276 template. The distribution of $I_c$ are from 0 to 397 A/cm at 77 K and self field. We have studied the microstructures of these films by using SEM, EDS and X-ray diffraction. The XRD and composition by EDS results of SmBCO film reveals subtle difference. But, the microscopic observation by SEM show the microcrack at the sample with low $I_c$.