• Transactions of the Korean hydrogen and new energy society
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• v.29 no.5
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• pp.442-449
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• 2018

Research on High temperature polymer electrolyte fuel cell (HT-PEMFC) has actively been conducted all over the world. Since the HT-PEMFC can be operated at a high temperature of $120-180^{\circ}C$ using phosphoric acid-doped polybenzimidazole (PBI) electrolyte membrane, it has considerable advantages over conventional PEMFC in terms of operating conditions and system efficiency. However, If the thermal distribution is not uniform in the stack unit, degradation due to local reaction and deterioration of lifetime are difficult to prevent. The thin plate separator reduces the volume of the fuel cell stack and improves heat transfer, consequently, enhancing the cooling effect. In this paper, a large area flow field of thin plate separator for HT-PEMFC is designed and sub-stack is fabricated. We have studied stack performance evaluation under various operating conditions and it has been verified that the proposed design can achieve acceptable stack performance at a wide operating range.

• Microbiology and Biotechnology Letters
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• v.19 no.4
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• pp.372-379
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• 1991

A rapid and simple quantitative assay method for aminoglycoside-3'- phosphotransferase (APH(3')) derived from E. coli ATCC 21990 was developed using the thin layer chromatographic densitometry, 3'-phosphorylated kanamycin B (3'-PKMB), product of APH (3') reaction, was separated from reaction mixtures by developing on the silica gel TLC plate with chloroform-methanol-ammonia water (3:4:3). The quantity of the 3'-PKMB was measured by densitometry after color development by ninhydrin method. Densitometric TLC assay for APH (3') was showed a good quantitative result and reproducibility. Sensitivity of this assay was 1.56 nmol of 3'-PKMB and could be analyzed many samples at same time. This method may be applicable for the analysis of inactivating enzymes of aminoglycoside antibiotics.

• Tribology and Lubricants
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• v.30 no.2
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• pp.116-123
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• 2014

The objective of this study is to model and simulate the nonlinear lubrication performance of the sliding part between the piston and cylinder wall in a hydrostatic swash-plate-type axial piston pump. A numerical algorithm is developed that facilitates simultaneous calculation of the rotating body motion and fluid film pressure to observe the fluid film geometry and power loss. It is assumed that solid asperity contact, so-called mixed lubrication in this study, invariably occurs in the swash-plate-type axial piston pump, which produces a higher lateral moment on the pistons than other types of hydrostatic machines. Two comparative mixed lubrication models, rigid and elastic, are used to determine the reaction force and sliding friction. The rigid model does not allow any elastic deformation in the partial lubrication area. The patch shapes, reactive forces, and virtual local elastic deformation in the partial lubrication area are obtained in the elastic contact model using a simple Hertz contact theory. The calculation results show that a higher reaction force and friction loss are obtained in the rigid model, indicating that solid deformation is a significant factor on the lubrication characteristics of the reciprocating piston part.

• Bulletin of the Korean Chemical Society
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• v.28 no.9
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• pp.1467-1471
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• 2007

The green-emitting CeMgAl11O19:Tb (CMAT) phosphor has been prepared at 1200 °C by the simple solid-state reaction using AlF3 as a self-flux. This preparation temperature is much lower than those (1500-1700 °C) for conventional solid-state reaction and spray pyrolysis method. In particular, the complete process to produce high-quality phosphor particles was carried out through the single-step heat treatment of the mixture of corresponding oxide-type metal sources. An addition of AlF3 as a self-flux significantly decreased the crystallization temperature of CMAT with plate-like shape. The particle morphology could be controlled from plate-like to spherical by using H3BO3 as an additional flux. Thus, an optimal morphology and luminescence characteristics of CMAT were achieved when both AlF3 and H3BO3 fluxes were simultaneously used. Compared with conventional solid-state process, which is accompanied by the calcination step(s), and other alternative liquid solution techniques such as sol-gel method and spray pyrolysis, no use of active precursors and liquid media that are harmful to the environment is a distinctive advantage for the industrial purpose.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.487-494
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• 1996

Simultaneous effects of $C_2H_4$ injection and heterogeneous chemical reactions on non-thermal plasma process to remove $SO_2$ and NOx from flue gas were investigated in the present experimental study. The present results showed that 40% of the electrical power can be reduced in $C_2H_4$ injection and heterogeneous chemical reaction are simultaneously included in the non-thermal plasma precess. As an effort to apply the non-thermal plasma technique to practical flue gas treatment system, a wire-plate type reactor which has technically similar geometry of industrial electrostatic precipitators is used instead of other types of reactors, such as wire-cylinder, packed-bed and surface discharge which are inappropriate to industrial application. In the present study, the photo pictures of positive streamer corona taken by ICCD camera, voltage and current oscillograms, and design criteria of a wire-plate type reactor are also shown, which are needed for industrial application of the non-thermal plasma process.

• Solar Energy
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• v.14 no.2
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• pp.91-101
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• 1994

Heat release characteristics of a CaO packed bed reactor which is used for a chemical heat storage device has been studied. We employed Cu-plate fins to release the heat of reaction of the CaO packed bed inside the reactor fast and effectively. Two-dimensional analysis of unsteady state heat flow inside the bed was performed as a function of time and under various conditions of the Cu-plates. It is noted that the time required to release the heat of reaction with Cu fins is reduced more than twice fast compared to that without Cu fins. That was largely dependent upon the number of Cu-plate, as well.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3194-3201
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• 2023

In water-cooled power reactor, hydrogen is generated in case of steam zirconium reaction during severe accident condition and later on in addition to hydrogen; CO is also generated during molten corium concrete interaction after reactor pressure vessel failure. Passive Autocatalytic Recombiners (PARs) are provided in the containment for hydrogen management. The performance of the PARs in presence of hydrogen and carbon monoxide along with air has been evaluated. Depending on the conditions, CO may either react with oxygen to form carbon dioxide (CO2) or act as catalyst poison, reducing the catalyst activity and hence the hydrogen conversion efficiency. CFD analysis has been carried out to determine the effect of CO on catalyst plate temperature for 2 & 4% v/v H₂ and 1-4% v/v CO with air at the recombiner inlet for a reported experiment. The results of CFD simulations have been compared with the reported experimental data for the model validation. The reaction at the recombiner plate is modelled based on diffusion theory. The developed CFD model has been used to predict the maximum catalyst temperature and outlet species concentration for different inlet velocity and temperatures of the mixture gas. The obtained results were used to fit a correlation for obtaining removal rate of carbon monoxide inside PAR as a function of inlet velocity and concentrations.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.211-216
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• 1997

The tungsten disulfide (WS$_2$) solid lubricant was synthesized by two different reaction processes, and the chemical and physical characteristics of synthesized WS$_2$ powder were analyzed in terms of the average particle size, morphology, crystalline phase. The solid WO$_3$ powder with the average size of 0.2 $\mu$m was reacted with CS$_2$ gas flowed with N$_2$ or 96% N$_2$ + 4% H$_2$ forming gas for 36 h and 24 h at 900$\circ$C respectively. In the case of vapour phase transport method, the 3.5 wt% iodine was added as a vapour transport reagent into the composition of tungsten and sulfur powders maintaining a constant molar ratio of W : S = 1 : 2.2. The mixture was then heat treated at 850$\circ$C for 2 weeks in vacuum The reaction product obtained showed the average size of 12 $\mu$m and the hexagonal plate shape of typical solid lubricant with 2H-WS$_2$ crystalline phase.

• Journal of the Korean Applied Science and Technology
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• v.21 no.4
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• pp.352-358
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• 2004

The firing reaction and calcination characteristics of the waste shellfish were examined for the future use as absorbent. The weight variation was measured according to thermal-decomposition using TGA and observed variation of the phase. The qualitative and quantitative analysis of the sample were performed using XRD and the structural analysis, SEM. The results of TGA and XRD experiments showed that the almost all of the raw Corbicula Japonica and Ostrea virginjca were changed from calcite to lime by firing and calcination reaction. The result of SEM experiment showed that the plate type of the raw sample was changed to circle type, so the surface area ratio was increased. Above results suggested that waste shellfish were usable as absorbent in the viewpoint of the reuse of resource and the decrease of environmental pollution.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.839-841
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• 2008

The mutagenicity after heating of different sugars (glucose, fructose, galactose, and tagatose) on the non-enzymatic browning reaction in different sugars and glycine model system was investigated. The model system containing 0.2 M glycine and 0.2 M of different sugars in 10 mL water was heated at $150{\pm}5^{\circ}C$ for 30 min. After heating, degree of non-browning reaction intensity and mutagenicity using Salmonella typhimurium TA 98 were examined. Heated glycine model systems containing different sugars increased their mutgenicity ranged from 30 to 372 revertant colonies. After heating for 40 min, mutagenicity was achieved with glycine model systems containing 4 different sugars with by 145, 356, 206, and 369 revertants per plate, respectively. The glycine model systems containing fructose or tagatose were significantly (p<0.05) higher mutagenic activity than glycine model systems containing glucose or galactose after 40 min of heating. The linear regression between Maillard reaction intensity and mutagenic activities (slope=32.38, $R^2=0.93$) indicates that mutagenicity could be fully ascribed to Maillard reaction products.