• Journal of the Korean Ceramic Society
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• v.28 no.8
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• pp.625-625
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• 1991

The specimens for the corrosion test were made by hot-pressing of SiC power with 2 wt% Nl2O3 and 10wt% Al2O3 additions at 2000℃ and 2050℃. The specimens were corroded in 37 mole% NaCl and 63 mole% Na2SO4 salt mixture at 1000℃ up to 60 min. SiO2 layer was formed on SiC and then this oxide layer was dissolved by Na2O ion in the salt mixture. The rate of corrosion of the specimen containing 10 wt% Al2O3 was slower than that of the specimen containing 2 wt% Al2O3. This is due to the presence of continuous grain boundary phase in the specimen containing 10 wt% Al2O3. The oxidation of SiC produced gas bubbles at the SiC-SiO2 interface. The rate of corrosion follows a linear rate law up to 50 min. and then was accelerated. This acceleration is due to the disruption oxide layer by the gas evolution at SiC-SiO2 interface. Pitting corrosion has found at open pores and grain boundaries.

• Resources Recycling
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• v.26 no.2
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• pp.33-38
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• 2017

Waste can be utilized as secondary or alternative fuel. Solid recovered fuel (SRF) and dried sewage sludge were combusted to investigate heavy metal emissions from their combusiton in this study. Content of copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), zinc (Zn), lead (Pb), arsenic (As) and mercury (Hg) of coal, SRF and dried sewage sludge were determined, respectively. Concentrations of these heavy metals in the combustion flue gas were also determined. As a result, emissions of gas-phase Cu, Cr, Cd, Ni, Zn, Pb and As compounds were found to be little. However, a significant amount of gas-phase Hg was emitted from combustion of coal, SRF and dried sewage sludge. While SRF showed a high mercury oxidation percentage in its combustion flue gas, dried sewage sludge showed a high level of gaseous mercury emission.

• Korean Journal of Food Science and Technology
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• v.19 no.4
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• pp.305-310
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• 1987

Whole soybean and soy flour were stored under two humidifies (65% and 85% RH) at $25^{\circ}C$ for 90 days to investigate the oxidation of total lipids. It was found that acid value and peroxide value of total lipids extracted from whole soybean and soy flour increased in proportion with the storage period. The change was more pronounced for soy flour stored at 85% RH. The increase of acid value and peroxide value was retarded by using the OPP/Al/PE film as packing material and the change of fatty acid was also reduced for whole soybean and soy flour. As for the change of fatty acid composition, polyunsaturated fatty acids such as linoleic and linolenic acid decreased while saturated fatty acid content increased in proportion with the storage period.

• Food Science of Animal Resources
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• v.30 no.3
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• pp.373-384
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• 2010

The present paper describes the effect of cooking temperature on objective meat qualities and volatile components in beef longissimus lumborum. Twenty samples of lumbar vertebrae longissimus muscle from Australian Black Angus (grain-fed and chiller aged for 29 d) were screened. Samples were cooked at 50, 70 or $90^{\circ}C$ in a pre-heated water bath for 1 h and uncooked raw samples were used as control. The results revealed that elevating the heating temperature from 50 to $90^{\circ}C$ led to a significant (p<0.05) increase in WB-shear force, total energy required for WB-shear force, cooking loss, pH and soluble collagen content, whereas a significant (p<0.05) linear decrease in protein solubility was observed. The results also revealed that the WB-shear force at $70^{\circ}C$ was significantly (p<0.05) lower than that observed at $50^{\circ}C$ and $90^{\circ}C$. However, the effect of temperature on cooking loss and protein solubility was notably (p<0.05) higher at $70^{\circ}C$. The detectable volatile components were mostly produced from fat oxidation, and temperature effects on the generation of volatile components were significantly (p<0.05) greater for aldehydes (hexanal, benzaldehyde, nonanal and octanal) than for ketones and hydrocarbons (hexane, benzene, decan, toluene and 3-methylnonane).

• Food Science of Animal Resources
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• v.29 no.6
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• pp.680-684
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• 2009

The effects of garlic and onion on the microbiological and physicochemical properties of irradiated ground beef patties were evaluated. Ground beef was mixed with 0.5%(w/w) minced garlic or 2.5%(w/w) minced onion, vacuum-packed in oxygen-impermeable nylon/PE bags and then electron beam-irradiated at 2.5 kGy. All samples were kept at $4^{\circ}C$ for 8 d. Irradiation resulted in a 2-log CFU/g reduction in both aerobic and coliform bacteria. The microbial counts gradually increased during storage, but those in beef that contained garlic or onion were 1-log CFU/g lower than those of the control samples after 8 d of storage. The pH value decreased during storage in all meat samples, but this decrease was greater in non-irradiated beef than in irradiated beef. The lipid oxidation, volatile basic nitrogen content and Hunter color values of raw patties were generally not affected by irradiation or the addition of garlic and onion. Sensory evaluation of cooked patties showed that the off-odor was less pronounced in samples that contained added garlic or onion than in control samples, and that the overall acceptability of beef formulated with garlic was the highest. Overall, the results of this study indicate that the addition of garlic or onion in combination with irradiation treatment enhanced the microbial quality and improved the sensory quality of irradiated ground beef.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.4
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• pp.563-568
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• 1997

Changes of chlorophylls and carotenoids and antioxidative characteristics of crude chlorophylls and carotenoids(CCC) of mustard leaf kimchi(MLK) were investigated during the fermentation at 15$^{\circ}C$ for 25 days. At the beginning of fermentation chlorophylls were decreased rapidly, however, all chlorophylls and chlorophyllides were converted to pheophytins and pheophorbides at the final stage of fermentation. Total chlorophyll content remained constantly during the fermentation but 43.7% destruction of carotenoids was observed at 25 days of fermentation. Antioxidative activities of CCC from MLK against autoxidation of linoleic acid were significant(p<0.05) and much higher than those of $\alpha$-tocopherol. Fermentation period did not affect antioxidative activities of CCC of MLK. When the CCC of MLK was added to the autoxidation system of linoleic acid, degradation of total chlorophylls were observed to be slower than that of total carotenoids.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.5
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• pp.503-508
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• 1991

The salted and dried mullet(Mugil Japonicus) roe had about 42% of protein and 41% of lipid content as major compoments. Therefore the lipid oxidation and the deterioration of protein occurred during drying and storage periods. In order to keep the good quality of the dried roe, acid, peroxide, thiobarbituric acid value and the contitutional amino acid were studied in the different drying air velocities at the conditions of 60% R.H. and $20^{\circ}C$ of drying air temperature. The optimum air velocity showed 2m/sec, which was excellently superior to the lipid and protein quality than those of other air velocities on the dried mullet roe. The drying period shortened from 20 days in the conventional processing method to 7 days in the modified processing method that had 2m/sec of drying air velocity. The drying rate curve had only a falling-rate drying period and not to have a constant-rate drying period.

• Polymer(Korea)
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• v.35 no.6
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• pp.565-573
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• 2011

The nanocomposites containing graphene oxide (GO) were prepared in order to improve the mechanical properties of poly(methyl methacrylate)/aluminum hydroxide (PMMA/AH) composites. GO was prepared from graphite by oxidation of Hummers method followed by exfoliation with thermal treatment. The surface of GO was modified by oxygen plasma in various exposure times from 0 to 70 min to improve interfacial compatibility. Compared with PMMA/AH composites, the nanocomposites containing GO modified with oxygen plasma for the exposure time up to 50 min showed significant increases in flexural strength, flexural modulus, Rockwell hardness, Barcol hardness, and Izod impact strength. The morphology of fracture surface showed an improved interfacial adhesion between PMMA/AH composites and GO, which was properly treated with oxygen plasma. The mechanical properties of nanocomposites were deteriorated by increasing the content of GO above 0.07 phr due to the nonuniform dispersion of GO.

• Korean Journal of Microbiology
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• v.53 no.4
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• pp.320-322
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• 2017

A betaproteobacterium strain GR16-43 was isolated from a surface layer of the Geomnyong Pond in Republic of Korea by a dilution-to-extinction culturing method. We report the whole genome sequence of the strain GR16-43, which contains 4,806,848 bp with a G + C content 67.12%, and to include 4,424 protein-coding genes and 47 transfer RNA genes. The genome was determined to contain the genes encoding carbon monoxide dehydrogenase, nitrate reductase, nitrite reductase, nitric oxide reductase, and the sulfur oxidation (sox) gene cluster, highlighting the potential importance of the bacterial group represented by the strain in the cycling of inorganic elements. These results indicate that strain GR16-43 genome showed several traits indicating adaptation of the bacteria to living in freshwater environments.

• Bulletin of the Korean Chemical Society
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• v.9 no.6
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• pp.368-376
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• 1988

Transition metal PSSA ionomers containing Co(II), Ni(II), Cr(III), Ru(III), and Rh(III) are investigated by IR, Far-IR, UV-Vis and DSC. Reliable IR Spectroscopic criteria are established for assessing the degree of ion-exchange of PSSA ionomers and the local structures around metal cations in them. In the hydrated transition metal PSSA ionomers, the ionic groups are solvated by water molecules and there is no significant interactions between sulfonate group and metal cations. The visible spectra indicated that metal cations are present as [M$(H_2O)_6$]$^{n+}$ with Oh symmetry. Their $T_g$ values increase as the extent of ionic site concentration increases, but there is no direct dependence of $T_g$ on the nature of metal cations or their oxidation states. Thus, the water content in PSSA ionomer is found to have dominant influence on $T_g$ of hydrated transition metal PSSA ionomers. Dehydration of the hydrated transition metal PSSA ionomers results in direct interaction between ionic groups and significant color changes of the ionomers due to the changes of the local structures around metal cations. On the base of spectral data, their local structures are discussed. In case of dehydrated 12.8 and 15.8 mol % transition metal PSSA ionomers, no glass transition is observed in 25-$250^{\circ}C$ region and this is believed to arise from the formation of highly crosslinked structures caused by direct coordination of sulfonate groups of metal cations. In the 6.9 mol % transition metal PSSA ionomers, the glass transition is always observed whether they are hydrated or dehydrated and this is though to be caused by the sufficient segmental mobility of the polymer backbone.