• Korean Journal of Ichthyology
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• v.23 no.2
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• pp.87-94
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• 2011

To find the preliminary environmental conditions for a short-time transport of living olive flounder, Paralichthys olivaceus, the stress response and physiological metabolic activity of the cultured fish to feed deprivation and slow temperature descending ($15.8^{\circ}C{\rightarrow}13.3^{\circ}C$) were monitored for 8 days. The monitored variables were the plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), glucose (GLU), total protein (TP), electrolytes ($Na^+$, $K^+$, $Cl^-$) and thyroid hormones ($TT_4$, $TT_3$, $FT_4$ and $FT_3$). In food deprivation experiment for 8 days, we did not find any statistical change of level in AST, ALT and electrolytes ($Na^+$, $K^+$, $Cl^-$), but found a significant decrease in TP and GLU. In thyroid hormones, the levels of four hormones in plasma were all showing a tendency to decrease. Especially, $FT_4$ and $TT_3$ were significantly decreased, indicating a withering of physiologic activity. In the temperature test, although no any significant change in AST, TP and electrolytes ($Na^+$, $K^+$, $Cl^-$), we observed a significant decrease of ALT and GLU following to temperature descending from $15.8^{\circ}C$ to $13.3^{\circ}C$ (P<0.05). In the levels of thyroid hormones, any significant change was not observed for experimental period. We conclude that the stress response and physiological activity of olive flounder were more influenced by feed deprivation than slow temperature descending at a transport of living fish, and plasma GLU appears to be sensitive factor to physiological metabolic activity, indicating that it could be used as a monitering mark or index for a health inspection of the fish.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.1-7
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• 2017

Cobalt silicide was used as a counter electrode in order to confirm its reliability in dye-sensitized solar cell (DSSC) devices. 100 nm-Co/300 nm-Si/quartz was formed by an evaporator and cobalt silicide was formed by vacuum heat treatment at $700^{\circ}C$ for 60 min to form approximately 350 nm-CoSi. This process was followed by etching in $80^{\circ}C$-30% $H_2SO_4$ to remove the cobalt residue on the cobalt silicide surface. Also, for the comparison against Pt, we prepared a 100 nm-Pt/glass counter electrode. Cobalt silicide was used for the counter electrode in order to confirm its reliability in DSSC devices and maintained for 0, 168, 336, 504, 672, and 840 hours at $80^{\circ}C$. The photovoltaic properties of the DSSCs employing cobalt silicide were confirmed by using a simulator and potentiostat. Cyclic-voltammetry, field emission scanning electron microscopy, focused ion beam scanning electron microscopy, and energy dispersive spectrometry analyses were used to confirm the catalytic activity, microstructure, and composition, respectively. The energy conversion efficiency (ECE) as a function of time and ECE of the DSSC with Pt and CoSi counter electrodes were maintained for 504 hours. However, after 672 hours, the ECEs decreased to a half of their initial values. The results of the catalytic activity analysis showed that the catalytic activities of the Pt and CoSi counter electrodes decreased to 64% and 57% of their initial values, respectively(after 840 hours). The microstructure analysis showed that the CoSi layer improved the durability in the electrolyte, but because the stress concentrates on the contact surface between the lower quartz substrate and the CoSi layer, cracks are formed locally and flaking occurs. Thus, deterioration occurs due to the residual stress built up during the silicidation of the CoSi counter electrode, so it is necessary to take measures against these residual stresses, in order to ensure the reliability of the electrode.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.557-564
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• 2021

Sr_0.92Y_0.08Ti_1-xV_xO_3-δ (SYTV) with perovskite structure was investigated as an alternative anode to utilize H₂S containing fuels in solid oxide fuel cells. To improve the electrochemical performance of Sr_0.92Y_0.08TiO_3-δ (SYT), vanadium(V) was substituted to titanium(Ti) at the B-site of the SYT perovskites. The SYTV synthesized by the Pechini method was chemically compatible with the YSZ electrolyte without additional by-products formation under the cell fabricating conditions. As increasing V substitution amounts, the oxygen vacancies increased, resulting to increasing ionic conductivity of the anode. The cell performance in pure H₂ at 850 ℃ is 19.30 mW/cm² and 34.87 mW/cm² for a 1 mol.% and 7 mol.% of V substituted anodes, respectively. The cell performance using H₂ fuel containing 1000 ppm of H₂S at 850 ℃ was 23.37 mW/cm² and 73.11 mW/cm² for a 1 mol.% and 7 mol.% of V substituted anodes, respectively.

• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.296-302
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• 2019

Ganjang-gejang (soy sauce-marinated crab) is a ready-to-eat (RTE) seafood and is also one of the most popular traditional dishes in Korea. It is generally prepared by washing raw blue crabs and then preserving them in soy sauce. Since this process does not involve cooking or any treatment with heat, it is difficult to control the microbiological quality of the final product. Thus, the objectives of this study were to compare the efficacies of various sanitizers in eliminating microorganisms on raw blue crab during the washing step and to evaluate the effectiveness of chitosan on the inhibition of microbial growth in the ganjang-gejang during storage. The raw blue crabs were submerged in chlorinated water (50 mg/L), peracetic acid (40 mg/L), acetic acid (5%) and lactic acid (5%) for 10 min at $25^{\circ}C$, respectively. The blue crabs treated with 5% acetic acid were marinated with soy sauce containing 0.5 and 1% of soluble chitosan, followed by storing them at 4 and $12^{\circ}C$ for up to 30 days. Results show that 5% acetic acid reduced the microbial populations on the blue crabs by 1.5 log CFU/g, which was significantly higher than those of other treatments. Based on these results, 5% acetic acid was selected for the washing step. The microbial populations of all ganjang-gejang samples significantly increased to about 8.0 CFU/g at $12^{\circ}C$ for 7 days. At $4^{\circ}C$, the microbial populations of the products containing 1% chitosan increased by about 2.9 CFU/g for 20 days, which were significantly lower than those (4.2-4.5 log CFU/g) of the products without and with 0.5% chitosan. Thus, these results suggest that 5% acetic acid washing of raw blue crabs and the addition of 1% chitosan in ganjang-gejang could improve the microbiological quality of the final products under refrigerated condition.