• Journal of the Korean Ceramic Society
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• 제34권3호
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• pp.303-313
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• 1997

To enhance the strength and formability of MCFC matrixes, alumina/${\gamma}$-LiAlO2 fiber-reinforced ${\gamma}$-LiAlO2 ma-trixes have been investigated. The MCFC matrixes with the thickness of 500~600 ${\mu}{\textrm}{m}$ were prepared by tape-casting of the slurry containing 10~30wt% fibers, followed by heat-treating up to $650^{\circ}C$. The porosity of fi-ber-reinforced matrixes decreased with the content of fibers, while the appropriate porosity(50~60%) for MCFC matrixes could be attained by adding larger ${\gamma}$-LiAlO2 particles with the diameter of about 50${\mu}{\textrm}{m}$ up to 50 wt%. The optimum length and content of the alumina fiber, both in the alignment of fibers and the enhancement of the strength, were found to be below 250${\mu}{\textrm}{m}$ and 20 wt%, respectively. On the other hand, the strength(156 gf/$\textrm{mm}^2$) of the ${\gamma}$-LiAlO2 matrix reinforced with ${\gamma}$-LiAlO2 fibers prepared in this study was improved by 20~40% in comparison with the alumina-fiber-reinforced matrix. It was also found that the alu-mina-fiber-reinforced matrix was completely corroded in molten carbonates but the ${\gamma}$-LiAlO2 was not.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제25권12호
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• pp.943-948
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• 2012

A new water energy harvester module, which is composed of piezoelectric bimorph cantilevers, harvesting circuit and a shaft with 16 impellers at a center axis, was fabricated for energy harvesting application. High energy density $Pb(Zr_{0.54}Ti_{0.46})O_3$ + 0.2 wt% $Cr_2O_3$ + 1.0 wt% $Nb_2O_5$ (PZT-CN) thick film obtained by tape casting method was used for the bimorph cantilever. The PZT-CN bimorph cantilever with a proof mass of 49 g exhibited extremely high output power of 22.5 mW (24 $mW//cm^3$) at resonance frequency of 11 Hz. In addition, the fabricated water energy harvester has a cylindrical structure with 48 bimorph cantilevers clamped at inner surface. A significantly high output power of 433 mW was obtained at a rotation speed of 120 rpm with a resistive load of $500{\Omega}$ for the water energy harvester.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.13-16
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• 2008

Solid oxide fuel cell(SOFC) is an electrochemical energy conversion system with high efficiency and low-emission of pollution. In order to reduce the operating temperature of SOFC system under $800^{\circ}C$, the thickness reduction of YSZ electrolyte to be as thin as possible, e.g., less than 10 ${\mu}m$ are considered with the microstructure control and optimum design of unit cell. Methods for reducing the thickness of YSZ electrolyte have been investigated in coin cell. Moreover, a large unit cell($8cm{\times}8cm$) for SOFC was fabricated using an anode-supported electrolyte assembly with a thinner electrolyte layer, which was prepared by a tape casting method with a co-sintering technique. we studied the design factors such as active layer, electrolyte thickness, cathode composition, etc,. by the coin type of unit cell ahead of the fabrication process of a large unit cell and also reviewed about the evaluation technique of a large size unit cell such as interconnect design, sealing materials and current collector and so forth. Electrochemical evaluations of the unit cells, including measurements such as power density and impedance, were performed and analyzed. Maximum power density and polarization impedance of coin cell were 0.34W/$cm^2$ and $0.45{\Omega}cm^2$ at $800^{\circ}C$, respectively. However, Maxium power density of a large unit cell($5cm{\times}5cm$) decreased to 0.21W/$cm^2$ at $800^{\circ}C$ due to the increase of ohmic resistance. However, It was found that the potential value of a large unit cell loaded by 0.22A/$cm^2$ showed 0.76V at 100hrs without the degradation of unit cell.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제29권10호
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• pp.601-607
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• 2016

Piezoelectric thick films of soft $Pb(Zr,Ti)O_3$ (PZT) based commercial material (S55) were fabricated using a conventional tape casting method. Ag-Pd electrodes were printed on the piezoelectric film at room temperature and all 5 layered films with a dimension of $12mm{\times}16mm$ were successfully laminated for a multi-layered piezoelectric ceramic actuator. The laminated specimens were co-fired at $1,100^{\circ}C$ for 1 h. A flat layered and dense microstructure was obtained for the $112{\mu}m$ thick piezoelectric actuator after sintering process. Thereafter, a prototype piezoelectric speaker was fabricated using the multi-layered piezoelectric ceramic actuator which can operate as a bimorph. Its SPL (sound pressure level) characteristic was also evaluated for speaker application. Frequency response revealed that the output SPL with a root mean square voltage of 10 V increased gradually to the highest peak of 87.5 dB for 1.5 kHz and exhibited a relatively stable behavior over the measured frequency range (${\leq}20kHz$) at a distance of 10 cm, implying that the fabricated piezoelectric speaker is potential for speaker applications.

• Transactions of the Korean hydrogen and new energy society
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• 제22권5호
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• pp.599-608
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• 2011

The Ni-Al anodes of the molten carbonate fuel cell (MCFC) with three different structures were successfully fabricated in order to reduce the thickness of the anode down to 0.3 mm; one was the non-supported anode made by a conventional tape casting method, and others were the supported anodes made by lamination or direct casting on the nickel screen. It was seen from the physical analyses and cell operation that the supported thin anodes made by direct casting showed good mechanical strength and cell performance because of a good contact between the anode materials and the support. The single cell using the above anode showed the cell voltage of 0.858 V at the current density of 150$mA/cm^2$ with the nitrogen cross-over of only 0.6% at the operation time of 1,000 h, which was similar to the performance of the conventional thick (0.7 mm) anode. The ability to utilize a thin configuration of anode should cut down the amount of nickel alloy and consequently reduce its manufacturing cost.

• Journal of the Korean Ceramic Society
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• 제31권9호
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• pp.969-974
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• 1994

After adding 8Y-ZrO2 powders to 3Y-ZrO2 powders at ratios of 0, 33, 50, 67, and 100% by weight, the mixed yttria-stabilized zirconia specimens were fabricated into thin plate using tape~casting method and then sintered at 150$0^{\circ}C$ for 4h in air. The crystalline structure, microstructure and electrical properties of the sintered zirconia thin plates were investigated by using X-ray diffractometer, scanning electron microscope and impedance analyser, respectively. At the temperatures higher than 75$0^{\circ}C$, the sintered thin plate with 33% 8Y-ZrO2 content shows higher mechanical properties and lower electrical resistivity than 8Y-ZrO2 thin plate which is generally used as an electrolyte for solid oxide fuel cells. This is due to the fact that the zirconia thin plates with low 8Y-ZrO2 content maintain the slope of low temperature region up to high temperatures, whereas at temperatures higher than 50$0^{\circ}C$ the slope decrease in the zirconia thin plates with high 8Y-ZrO2 content.

• Journal of The Korean Society of Integrative Medicine
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• 제5권4호
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• pp.49-55
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• 2017

Purpose : In this study we tested the hypothesis that eucommia ulmoides (EU) extract would improve disuse-induced muscle atrophy following hindlimb immobilization. Method : The hindlimb immobilization was performed with casting tape to keep the left ankle joint in a fully extended position. The rats in EU treated group were orally administrated with eucommia ulmoides water extract. After 2 weeks of immobilization, all animals were sacrificed, and the whole gastrocnemius muscles were dissected from both legs. The morphology of right and left gastrocnemius muscles in both EU and control groups were assessed by hematoxylin and eosin staining. Results : Eucommia ulmoides extract represented the significant protective effects against the reductions of the gastrocnemius muscles weight and average cross section area to compared with Control group. Conclusion : Eucommia ulmoides has protective effects against immobilization induced muscle atrophy.

• Electrical & Electronic Materials
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• 제9권2호
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• pp.138-145
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• 1996

A multilayer piezoelectric transformer (MPT) which generates a high voltage dc power with low driving voltage and high voltage setup ratio was made by the tape casting method. The measured electrical characteristics of the MPT agreed with the results simulated from the equivalent circuit of the MPT. With increasing the number of layer in the MPT, the resonance curve of the input cur-rent revealed an asymmetry due to the increasing input capacitance, while that of output dc voltages revealed symmetry. The MPT which has very thin layer was excellently characterized as low driving voltage and high voltage setup ratio. The output dc voltage is nonlinearly influenced by the number of layer in the MPT.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제21권6호
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• pp.524-529
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• 2008

In this paper, in order to develop low loss multilayer actuator, piezoelectric properties of PZW-PMN-PZT multilayer actuator sintered at $900^{\circ}C$ low temperature were investigated according to the number of multilayer. The multilayer actuator was fabricated using tape casting method and used pure Ag internal electrode. The density above $8.0\;g/cm^3$ was obtained at all specimens. With increasing number of multilayer, effective electromechanical coupling factor($k_{eff}$) was increased. $k_{eff}$ of multilayer actuator shows the maximum value of 0.283 at 11 layers actuator. However, effective mechanical quality factor(Qm') was decreased according to the increase of number of multilayer. The Qm' of multilayer actuator showed the maximum value of 920 at 5 layers actuator.

• Journal of Sensor Science and Technology
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• 제17권4호
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• pp.273-280
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• 2008

Monolith aperture-type oxygen sensors with simple structure of YSZ(pin-hole)/Pt/ YSZ(solid electrolyte)/Pt were fabricated by co-firing technique. To enhance the yield of productivity, a couple of YSZ green sheets for diffused barrier and solid electrolyte were prepared by tape-casting and co-firing method. The limit current characteristics of the oxygen sensors were measured between 500 and $650^{\circ}C$ The heating temperature of $600^{\circ}C$ was optimum as a portable oxygen sensor in the range of oxygen concentration from 0 to 75 vol%. Linear proficiency of limit current behavior as a function of oxygen concentration was controlled by the variation of aperture dimension. The fabricated oxygen sensors showed the stable sensing output for 30 days. Gas leakage in bonding area due to warping, cracking and thermal cycling was not found in the period.