• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.4
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• pp.316-322
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• 1983

In order to obtain elementary data of enzymatic browning of apples and apple products and to examine effectively inhibitory method of browning, we extracted polyphenol oxidase (EC 1.10.3.1) from apple (Ralls Janet) and investigated its general properties. The optimum conditions for the enzyme reaction were pH 6.0 and temperature of $30^{\circ}C$. The enzyme was very stable at pH 4.0, and at the range of pH 5.0-9.0 its activity was above 80% compared with pH 4.0. The enzyme was very stable by heating at $40^{\circ}C$ for 1 hour, and almost 50% of enzyme activity was lost by heating at $60^{\circ}C$ for 30 minutes. The polyphenol oxidase activity was enhanced by the addition of $Cu^{2+}$ and $Mn^{2+}$, respectively, meanwhile $Na^+$, $Hg^{2+}$ and $Co^{2+}$ inhibited the enzyme activity. The enzyme activity was greatly decreased in the presence of inhibitors such as cysteine, sodium metabisulfite and ascorbic acid. The polyphenol oxidase greatly catalyzed the oxidation of o-diphenols such as chlorogenic acid and catechol, which suggests that main substrate of polyphenol oxidase is o-diphenol compounds.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.12
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• pp.1497-1502
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• 2007

The antioxidant effect of Korean cabbage kimchi containing 20% of sea tangle (SK) was studied in the rats fed with high fat diet (HFD) for 8 weeks. The rats (n=40) were divided into four experimental groups as a high fat diet group (HFD), HFD supplemented either with Korean cabbage kimchi used as experimental control (HCK), with SK (HSK), or with J-kimchi (HJK) that was purchased at the local market. The amount of kimchi supplemented was 10%. DPPH radical scavenging activities of SK were significantly higher than those of CK. Kimchi suppressed the hepatic lipid peroxidation significantly, especially by HSK (p<0.05). Inhibition of thiobarbituric acid reactive substances (TBARS) formation in HSK was the greatest among the kimchi groups (p<0.05). The activities of $Cu{\cdot}Zn$-superoxide dismutase (SOD), Mn-SOD and catalase decreased significantly (p<0.05) by kimchi supplementation. SOD and catalase activities of HSK were found to be the lowest among the kimchi groups. The decreased enzyme activity in kimchi group might be due to the less amount of lipid peroxides produced in the rats fed kimchi diet. The lowest antioxidative enzyme activities observed in HSK were in line with those of hepatic POV and TBARS of HSK. Our findings confirmed that kimchi acted as an antioxidant in the high fat fed rats and its antioxidant effect was significantly increased by the addition of sea tangle.

• Resources Recycling
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• v.8 no.5
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• pp.19-27
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• 1999

The desilica~ilalioc~h~ar .~ctcrisocs or conveutcu dust for molten pg iron has bee11 sludled for the pulposc of converter dust reuse. Desiloconizalir~ne ff~c~encwya s observed 10 be increased with increasing feeding rate of dust, and there was 110 cffccl to Lhe des~lica~~iratiearlfli cio~cyfo r the addtioolI CaO Ln dust. In ~noslc ases, the dcs~l~conizaliornea ction was ucconlpl~shed wrthin 10 minutes regadless of thc dust cornpasilim In addition lo the desil~comzat~oenfl ect, the rzmow~lc hal-i~cteristo~fs M u, P. C, and S from mallen iron by convcrtcr dust also have been in\~esligataled. CuO m thc converlel. dust was observed to ~educc the demanganizi~tion eflect and slag laming phenomenon and make thc dephosphoriralion pn,ce*s easler.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.5
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• pp.218-227
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• 2021

A thick film NTC thermistor for low temperature co-firing was manufactured by printing and sintering a paste prepared using NTC powder of Mn_1.5Ni_0.4Co_0.9Cu_0.4O₄ composition, lead free frit, and RuO₂ on a 96 % alumina substrate. The effect of frit and RuO₂ on the electrical properties of thick film NTC thermistor was studied. The resistance of the thick film NTC thermistor was higher than that of the bulk phase sintered at the same temperature, but it was found that the negative resistance temperature characteristic appeared more clearly and linearly in the resistance - temperature characteristic. On the other hand, the area resistance decreased as the sintering temperature increased, and the area resistance increased as the amount of frit added increased. The B constant of the thick film NTC thermistor was 3000 K or higher. Among them, it was found that the B constant of the thick film NTC thermistor made of paste with 5 wt% of frit added and sintered at 900℃ showed the highest B constant. Also, it can be seen that the area resistance decreased with the addition of RuO₂, and the change in the area resistance decrease of the thick film NTC thermistor obtained by sintering the paste containing 5 wt% of RuO₂ at 900℃ is the most obvious.

• Journal of The Korean Society of Grassland and Forage Science
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• v.35 no.2
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• pp.93-98
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• 2015

This study was conducted to investigate the effect of different stockpiled periods on the nutritive value and productivity of mixed orchardgrass tall-fescue pasture (MOTP). This experiment was conducted at Jeju (island), South Korea, from Sep. 2012 to Nov. 2012. The DM yield of the MOTP had the highest in treatment in late August (2,983 kg/ha). The DM yields of swards were increased significantly by shortening the stockpiled period. The CP of the MOTP was 16.5% to 18.16%, and there did not appear to be a consistent trend in accordance with the duration of the stockpiled periods. The NDF and TDN content of the MOTP increased with the delay of the stockpiled periods, but there is a significant difference between the short- and long-stockpile periods; however, the ADF content of the MOTP decreased with shortened stockpile periods, but again, there is a significant difference between the two periods. In addition, P, Ca, Mg, Na, and Zn of MOTP increased by delaying the stockpile period, but Mn and Cu of MOTP decreased. As shown in the results of this research, the yield of MOTP was not increased by the atrophy of the growth of MOTP due to high temperatures in case where the MOTP was stockpiled from the beginning of August. The stockpile period of MOTP should therefore be started at the end of August to yield a stockpile of MOTP in the autumn.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.4
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• pp.309-317
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• 2005

A study on the separation of $^{99}Tc,\;^{94}Nb,\;^{55}Fe,\;^{90}Sr\;and\;^{59/63}Ni$ in various radioactive wastes discharged from nuclear power plants has been performed for a use in their quantification which is indispensible for the evaluation of the radionuclide inventory Ni was recovered along with Ca, Mg, Al, Cr, Ti, Mn, Ce, Na, K, and Cu through the sequential separation procedure of Re(as a surrogate of $^{99}Tc$), Nb, Fe and Sr by anion exchange and Sr-Spec extraction chromatography. In this research, chemical separation of Ni from the co-existing elements was investigated by cation exchange and Ni-Spec extraction chromatography. Precipitation behaviour of Ni and the co-existing elements with dimethylglyoxime(DMG) was investigated in ammonium $citrate/ethanol-H_2O$ and tartaric $acid/acetone-H_2O$ in order to purify separated Ni fractions and to prepare $^{59/63}Ni$ source for the radioactivity measurement using a gas proportional counter. Recovery of Ni separated through ion exchange chromatographic separation procedure was $92.1\%$ with relative standard deviation of $0.9\%$. In addition, recovery of Ni with DMG in the tartaric $acid/acetone-H_2O$ was $85.6\%$ with relative standard deviation of $1.9\%$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.2
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• pp.106-117
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• 2006

We measured the concentrations of organic matter and metallic elements (Al, Fe, Cr, Mn, Ni, Cu, Zn, As, Cd, Pb and Hg) in the surface sediments of Masan Harbor (in the southern sea, Korea) to evaluate the geochemical characters of sediment and the pollutions by organic matter and metallic elements. The mean grain size of the surface sediments in the study area ranged from $5.6{\phi}$ to $7.8{\phi}$, indicating silt sediment. The water content of the surface sediments exceeded 60% except at some stations. The contents of ignition loss (IL), total organic carbon (TOC) and total nitrogen (TN) ranged from 7.2-14.3%, 1.2-3.2%, and 0.10-0.28%, respectively. Based on the C/N ratios, the organic matter in the surface sediments of Masan Harbor may originate from terrigenous sources including fluvial inputs (mainly sewage in urban areas). The chemical oxygen demand (COD) and acid volatile sulfide (AVS) ranged from $11.3-29.9\;mgO_2/g\;dry$ and 0.20-4.47 mgS/g dry, respectively, and low concentrations were observed near a shipping route. In addition, the concentrations of metallic elements showed large spatial variations in Masan Harbor and the distributions of metallic elements were also comparable to those of organic matter. This implies that the distributions of organic matter and metallic elements in the surface sediments of Masan Harbor are mainly controlled by biogenic matter and artificial action (mainly dredging). In addition, we calculated the enrichment facto. (EF) and geoaccumulation index (Igeo) in order to evaluate pollution by metallic elements. The enrichment of metallic elements relative to Al was three to eighteen times higher at the study sites, compared to levels in the Earth's crust except for Fe, Ni and Mn. In addition, the Igeo class indicated that the surface sediments in the study area were moderately to strongly polluted in terms of metallic elements.

• Journal of Life Science
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• v.22 no.7
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• pp.857-862
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• 2012

This study was conducted to investigate the effects of Opuntia humifusa supplementation on lipid peroxidation and superoxide dismutase (SOD) protein expression at resting state in various organs of rats fed a high-fat diet. Sixteen Sprague-Dawley male rats, 6 weeks of age, were randomly divided into two groups: a control diet group (CG, n=8) and an experimental diet group (EG, n=8). They were given a high-fat diet (CG) or a diet supplemented with 5% of O. humifusa (EG) for 8 weeks. The results showed that the malondialdehyde (MDA) levels of the kidney and the liver were significantly lower in the EG group than in the CG group (p<0.01). In addition, the MDA levels in the skeletal muscle of the EG group tended to be lower than those in the CG group, but this difference was not significant. The Cu, Zn-SOD protein expression in the kidney of the EG group was significantly increased compared with that of the CG group (p<0.01). The Mn-SOD protein expression in the skeletal muscle of the EG group was significantly increased compared with that of the CG group (p<0.01). These results suggest that O. humifusa supplementation has antioxidative properties, which are exerted in a specific organ manner, and that it inhibits the action of lipid peroxidation and the expression of SOD in rats fed a high-fat diet.

• Microbiology and Biotechnology Letters
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• v.4 no.4
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• pp.131-137
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• 1976

Aspergillus niger S-1 was proved to be a good hesperidinase producer which have been selected for naringinase utilization. Enzyme of this strain had good characteristics and purified relative high degree with good recovery by ammonium sulfate or aceton treatment. Results obtained were summarized as follows (1) The enzyme was most active at 60$^{\circ}C$, when the reaction was performed in the pH 4.0 for 30min. Optimum pH for enzyme activity was 5.0 and activity was retained 78％ at pH value 3.5. (2) Hesperidinase activity retained 95％ of its full activity after treatment at 60$^{\circ}C$ for 30min at pH value 4.0., 70％ at 70$^{\circ}C$ and 65％ at 80$^{\circ}C$. Most stable pH of this enzyme was showed 5.0 after treatment for 24hr at 4$^{\circ}C$ (3) Only Magnesium ion activated enzyme reaction, while other metallic ions, Cu$\^$＋＋/, Mn$\^$＋＋/, Pb$\^$＋＋/, Mo$\^$＋＋/, Ag$\^$＋＋/, Hg$\^$＋＋/ inhibited. (4) Eleven fold purification with 35％ recovery was obtained in the case of 60％ aceton treatment and 10-fold purification with 5.6％ recovery was showed with 40％ aceton comparing to the crude extract Enzyme. (5) Crude enzyme precipitated with 0.4-0.6 saturated ammonium sulfate contained 13f6 of the original enzyme activity with 48-fold increase in specific activity and enzyme has been purified 25 fold with a yield 19％ by 0.6-5.8 saturation. (6) Hesperidinase formation was noticeably increased by addition of small amount of orange-peel extraction on the wheat bran medium.

• Journal of Animal Science and Technology
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• v.51 no.2
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• pp.171-176
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• 2009

A bacterial strain producing intracellular phytase was isolated from cultivable soil near cowsheds and identified as a fluorescent Pseudomonas sp. BUN1. The BUN1 phytase, partially purified by cation and anion exchange chromatography, exhibited its optimal activity at $40^{\circ}C$ and pH 5.5. As for substrate specificity, it was very specific for phytate and showed little activity on other phosphorylated conjugates. Its activity was greatly inhibited by metal ions such as $Cu^{2+}$, $Cd^{2+}$, and $Zn^{2+}$. Addition of corn starch to PSM (phytasesynthetic medium) [0.5% sodium phytate, 0.5% $(NH_4)_2SO_4$, 0.5% KCl, 0.01% $MgSO_4\cdot7H_2O$, 0.01% $CaCl_2\cdot2H_2O$, 0.01% NaCl, 0.001% $FeSO_4\cdot7H_2O$, 0.001% $MnSO_4\cdot4H_2O$; pH 6.5] for the phytase production significantly induced its enzyme activity in comparison with other carbon sources tested.