• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.798-804
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• 2006

Co-planar type single chamber solid oxide fuel cell with patterned electrode on a surface of electrolyte has been fabricated by robo-dispensing method and microfluidic lithography. The cells were composed of NiO-GDC-Pd or NiO-SDC cermet anode, $(La_{0.7}Sr_{0.3})_{0.95}MnO_3$ cathode, and yttria stablized zirconia electrolyte. The cell performance at $900^{\circ}C$ was investigated as a function of electrode geometries, such as anode-to-cathode distance, numbers of electrode pairs. Relationship between OCV and I-V characteristics at the optimized operation condition was also studied by DC source meter under the mixed gas condition of methane, air, and nitrogen. An increase of anode-facing-cathode area leads to lower OCV due to intermixing between product gases of anode and cathode, which in turn decreases the oxygen partial pressure difference.

• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.865-871
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• 2006

In order to examine and compare the characteristics of two vitrified forms (AG8W1 and DG2) simulated for the operation of a commercial vitrification facility being constructed in Ulchin nuclear power plant, the vitrified forms were cooled by the natural cooling and annealing methods respectively. And the Product Consistency Test (PCT), compressive strength, thermal conductivity, specific heat, phase stability, softening point and Coefficient of Thermal Expansion (CTE) of the vitrified farms were experimented. Consequently, it was shown that there were no significant differences on the physiochemical properties of the vitrified forms performed the natural cooling and annealing.

• Journal of the Korean Ceramic Society
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• v.54 no.6
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• pp.492-498
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• 2017

A thermal barrier coating (TBC) with self-healing property for cracks was proposed to improve reliability during gas turbine operation, including structural design. Effect of healing agent on crack propagation behavior in TBCs with and without buffer layer was investigated through furnace cyclic test (FCT). Molybdenum disilicide ($MoSi_2$) was used as the healing agent; it was encapsulated using a mixture of tetraethyl orthosilicate and sodium methoxide. Buffer layers with composition ratios of 90 : 10 and 80 : 20 wt%, using yttria stabilized zirconia and $MoSi_2$, respectively, were prepared by air plasma spray process. After generating artificial cracks in TBC samples by using Vickers indentation, FCTs were conducted at $1100^{\circ}C$ for a dwell time of 40 min., followed by natural air cooling for 20 min. at room temperature. The cracks were healed in the buffer layer with the healing agent of $MoSi_2$, and it was found that the thermal reliability of TBC can be enhanced by introducing the buffer layer with healing agent in the top coat.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.477-482
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• 2006

In this study, a micro vapor compressor has been designed, fabricated and tested. The micro vapor compressor was made of silicon substrates and fabricated by micromachining process. The compressor is driven by a piezoelectric actuator which is widely used in microfluidic systems because of its strong force and rapid response. The actuator is a bimorph structure which consists of a silicon membrane and a piezoelectric ceramic film. A simulation work was conducted on the performance characteristics of the compressor. The simulation investigated the flow rate variation under various back pressure conditions. Experimental works were carried out on the operation of a compressor and the test results were compared with the simulation results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.4
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• pp.327-332
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• 2019

Recently, inverter control systems have attracted immense attention to increase the energy efficiency. However, such systems use repeated on/off high currents for linear operation control, instead of the prevalent step variable current control method. Hence, there arise concerns of personal and property damage, especially due to the durability, explosive characteristics, and operating speed of the fuse, which is responsible for safety and is one of the internal components using current control. Therefore, in this paper, we propose an IEC60127-4 SMD sub-miniature fuse, consisting of Ag-Cu alloys and ceramic powder for arc soothing. The IEC60127-4 SMD sub-miniature fuse has high durability and cut-off capacity, and operates safely in dangerous circumstances caused by the inverter control system.

• Korean Membrane Journal
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• v.1 no.1
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• pp.1-7
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• 1999

Pd-ceramic composite membranes and catalytic membrane reactors(CMR) have been studied for hydrogen and its isotopes (deuterium and tritium) purification and recovery in the fusion reactor fuel cycle. Particularly a closed-loop process has been studied for recovering tritium from tritiated water by means of a CMR in which the water gas shift reaction takes place. The development of the techniques for coating micro-porous ceramic tubes with Pd and Pd/Ag thin layers is described : P composite membranes have been produced by electroless deposition (Pd/Ag film of 10-20 $\mu$m) and rolling of thin metal sheets (Pd and Pd/Ag membranes of 50-70 $\mu$m). Experimental results of the electroless membranes have shown a not complete hydrogen selectivity because of the presence of some defects(micro-holes) in the metallic thin layer. Conversely the rolled thin Pd and Pd/ag membranes have separated hydrogen from the other gases with a complete selectivity giving rise to a slightly larger (about a factor 1.7) mass transfer resistance with respect to the electroless membranes. Experimental tests have confirmed the good performances of the rolled membranes in terms of chemical stability over several weeks of operation. Therefore these rolled membranes and CMR are adequate for applications in the fusion reactor fuel cycle as well as in the industrial processes where high pure hydrogen is required (i.e. hydrocarbon reforming for fuel cell)

• Membrane Journal
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• v.14 no.3
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• pp.192-200
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• 2004

It is an anaerobic germ that Lactobacillus cell concentrated using ceramic membrane has high stability and long lifetime as compared with polymeric membrane. The effects of operating pressure, temperature, crossflow velocity on cell harvesting have been studied. Also the variation of flux and transmembrane pressure (TMP) with increasing concentration ratio and the change of TMP at constant concentration ratio (volumetric concentration factor: VCF) regarding the optimization have been examined. It showed that the permeate flux increased gradually with the increasing of transmembrane pressure, crossflow velocity, and volumetric concentration factor. The higher initial flux was due to the reduction of viscosity at elevated temperature. However, as operating time progressed, the effect of temperature was negligible since the effect of viscosity became minor. As a result, that operate in a constant concentration ratio, decreased degree could know that become slowly although the flux decreases according as operating time progressed. The flux is a very stable in the condition of constant VCF range. The yield of Latobaciilus (PS 406) which was cultivated at $37^{\circ}C$ was concentrated about 4.9{\times}10^9$ after operation.

• Journal of Energy Engineering
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• v.21 no.4
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• pp.385-392
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• 2012

The purpose of this study is investigated on the combustion and the thermal characteristics of porous media burners which are many using for a condensing boiler recently. In addition, results of this study will be used the fundamental information to decide the burner type which will be applied to the future development of EGR(Exhaust gas recirculation) condensing boiler. Two flat type of burners made of a the metal fiber(MF) and the ceramic(CM) were selected and examined, experimentally. As experimental results, the emitted CO concentration of CM was higher than that of MF. However, the NO concentration of MF was higher than that of CM. The efficiencies of both burners were increased as increasing the burner capacity. While the efficiency of MF was higher than that of CM, regardless of the burner capacity. In the experimental range, MF is appropriated for the burner material and 0.8 of equivalence ratio is an optimal operation condition, regarding of the proportional control, the thermal efficiency and emitted NO and CO concentration based on the regulations of KS B standard and EN 677 standard.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5419-5424
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• 2014

A weld scallop is a small quadrant or half circle type hole installed in the weld line cross area for easy welding operation. Many types of T-bars with a scallop can be welded in a block assembly stage in shipbuilding. The difficulties arise from the fact that scallops are to be filled by build-up welding after welding of the cross line is complete. In this study, a non-scallop block joint welding method was developed using special type CBM (ceramic backing material). The wedge shaped CBM was devised to insert a CBM into just the V groove of weld line cross area without weld scallop. A saw-toothed shape was adopted for easy cutting of the unnecessary part in the CBM fitting process. The applicability of the developed method was verified through welding experiments based on the yard welding conditions.

• Clean Technology
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• v.12 no.3
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• pp.151-156
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• 2006

Combined membrane process of ceramic microfiltration (MF) and polymer ultrafiltration (UF) was optimized for the removal of color and total organic carbon (TOC) from textile wastewater. Membrane regeneration was performed for the efficient operation by backflushing and chemical cleaning. Flux of 10.3% increased by the pulse backflushing of 1 second every 2 minutes in ceramic microfiltration. Membrane regeneration of 97% was obtained by chemical cleaning with 0.1% sodium hydroxide in polymer ultrafiltration. The removal efficiency of TOC, color and SS (suspended solid) were 84.6%, 97.4% and 100%, respectively. The combined process was found to be suitable for the removal of color and residual organics from textile wastewater.