• Journal of Life Science
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• v.7 no.3
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• pp.228-233
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• 1997

A thiol protease has been isolated and partially purified from encysted brine shrimp Artemia franciscana using a four-step procedure(filtration, salting out, gel filtration and ion exchange chromatography). The optimum pH of the enzyme for caseinolytic activity was appeared to be 3.0, and the enzymematic activity was stable up to pH 6.0 but lost completely at the pH higher than 8.0. The optimal temperature of the enzyme was appeared to be 35$^{\circ}$C, and ninety percent of the enzyme activity was lost at 45$^{\circ}$C. Various metal ions, e.g., zinc, copper, iron, inhibited the enzyme activity; however, heavy metal chelator, e.g., EDTA, stimulated the enzyme activity. The protease was concluded to be a member of the thiol group protease, since it was inhibited by thiol protease inhibitors and iodoacetate. The protease was also concluded to be a acid protease based on optimum pH.

• Resources Recycling
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• v.28 no.3
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• pp.59-67
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• 2019

This study was conducted to fabrication pig iron containing copper and to reduce sulfur content pig iron. Roasting test was conducted for 1 ~ 9 hours at each temperature of $500^{\circ}C$, $700^{\circ}C$, and $900^{\circ}C$. In addition, the effect of oxygen partial pressure with 0.5, 0.8, and 1 atm was carried out for 30 minutes at $900^{\circ}C$. It was found that there is no effect to reduce sulfure in pig iron through roasting and oxygen partial pressures. The addition of CaO with 15 wt.% was found to reduce sulfur content up to 0.001 wt.%. The suitable temperature and reactive time for carbothermic reduction were $1600^{\circ}C$ and 30 minutes which shows the highest recovery rate of iron from the copper slag.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.6
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• pp.894-901
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• 2010

To measure the heavy metal contents of marine invertebrates, we collected 239 individuals representing 52 species from the eastern (Pohang), western (Gunsan), and southern (Tongyeong) coasts of Korea: 34 species of molluscan shellfish (Gastropoda and Bivalvia), 6 species of Cephalopoda, 8 species of Crustacea, and 4 other species. The mean levels of the heavy metals in the samples taken from the edible portion of each Gastropoda were high in the order of Zn ($21.471\;{\mu}g/g$), Cu ($4.115\;{\mu}g/g$), Mn ($0.868\;{\mu}g/g$), Ni ($0.254\;{\mu}g/g$), Pb ($0.238\;{\mu}g/g$), Cd ($0.154\;{\mu}g/g$), and Cr ($0.110\;{\mu}g/g$). The heavy metals in the Bivalvia were high in the order of Zn ($35.655\;{\mu}g/g$), Mn ($5.500\;{\mu}g/g$), Cu ($3.129\;{\mu}g/g$), Cd ($0.423\;{\mu}g/g$), Ni ($0.402\;{\mu}g/g$), Cr ($0.233\;{\mu}g/g$), and Pb ($0.232\;{\mu}g/g$). The heavy metals in the Cephalopoda were high in the order of Zn ($18.380\;{\mu}g/g$), Cu ($3.594\;{\mu}g/g$), Mn ($0.630\;{\mu}g/g$), Cr ($0.150\;{\mu}g/g$), Pb ($0.068\;{\mu}g/g$), Cd ($0.034\;{\mu}g/g$), and Ni ($0.030\;{\mu}g/g$). The heavy metals in the Crustacea were high in the order of Zn ($25.333\;{\mu}g$/g), Cu ($9.042\;{\mu}g/g$), Mn ($0.659\;{\mu}g/g$), Cr ($0.592\;{\mu}g/g$), Cd ($0.207\;{\mu}g/g$), Pb ($0.126\;{\mu}g/g$), and Ni ($0.094\;{\mu}g/g$). Therefore, the mean levels of the harmful heavy metals (Cd and Pb) in marine invertebrates were high in the order of Bivalvia>Crustacea＝Gastropoda>Cephalopoda. The average daily intakes of the heavy metals from the fisheries products were as follows: Cd ($6.88\;{\mu}g$), Cr ($19.13\;{\mu}g$), Cu ($137.02\;{\mu}g$), Mn ($156.13\;{\mu}g$), Ni ($11.39\;{\mu}g$), Pb ($7.01\;{\mu}g$) and Zn ($1,025.94\;{\mu}g$). The average weekly intakes of Cd, Cu, Pb and Zn from the fisheries products were 11.47%, 0.46%, 3.27% and 1.71% respectively, as compared with PTWI (Provisional Tolerable Weekly Intakes) established by FAO/WHO Expert Committee for Food Safety Evaluation.

• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.130-139
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• 2016

A bacterial strain, producing an excellent lipolytic enzyme, was isolated from the intestinal tracts of an earthworm (Eisenia fetida). The strain was identified as Aeromonas hydrophila by phenotypic, chemotaxonomic characteristics and 16S ribosomal DNA analysis, and was designated as Aeromona hydrophila PL43. The lipolytic enzyme from A. hydrophila PL43 was purified via 35−45% ammonium sulfate precipitation, DEAE-sepharose fast flow ion-exchange, and sephacryl S-300HR gel filtration chromatography. The yield of the purified enzyme was 3.7% and 2.5% of the total activity of crude extracts with p-nitrophenyl butyrate (pNPB) and p-nitrophenyl palmitate (pNPP) as substrates, respectively. The molecular weight of the purified enzyme was approximately 74 kDa using gel filtration, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and zymography. The optimal activity of purified enzyme was observed at 50℃ and pH 8.0 using pNPB, and 60℃ and pH 8.0 using pNPP. The purified enzyme was stable in the ranges 20− 60℃ and pH 7.0−10.0. The activity of purified enzyme was inhibited by PMSF, pepstatin A, Co²⁺, Cu²⁺, and Fe²⁺, but was recovered by metal chelating of EDTA. The K_m and V_max values of the purified enzyme were 1.07 mM and 7.27 mM/min using pNPB and 1.43 mM and 2.72 mM/min using pNPP, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.3
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• pp.195-207
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• 2000

Organic and inorganic characteristics including bacterial cell number, enzyme activity, nutrients, and heavy metals have been monitored in twelve acrylic experimental tanks for two weeks to estimate and compare self-purification capacities in two Korean wet-land environments, tidal flat and rice field, which are possibly different with the environments in other countries because of their own climatic conditions. FW tanks, filled with rice field soils and fresh water, consist of FW1&2 (with paddy), FW3&4 (without paddy), and FW5&6 (newly reclaimed, without paddy). SW tanks, filled with tidal flat sediments and salt water, are SW1&2 (with anoxic silty mud), SW3&4 (anoxic mud), and SW5&6 (suboxic mud). Contaminated solution, which is formulated with the salts of Cu, Cd, As, Cr, Pb, Hg, and glucose+glutamic acid, was spiked into the supernatent waters in the tanks. Nitrate concentrations in supernatent waters as well as bacterial cell numbers and enzyme activities of soils in the FW tanks (except FW5&6) are clearly higher than those in the SW tanks. Phosphate concentrations in the SW1 tank increase highly with time compared to those in the other SW tanks. Removal rates of Cu, Cd, and As in supematent waters of the FW5&6 tanks are most slow in the FW tanks, while the rates in SW1&2 are most fast in the SW tanks. The rate for Pb in the SW1&2 tanks is most fast in the SW tanks, and the rate for Hg in the FW5&6 tanks is most slow in the FW tanks. Cr concentrations decrease generally with time in the FW tanks. In the SW tanks, however, the Cr concentrations decrease rapidly at first, then increase, and then remain nearly constant. These results imply that labile organic materials are depleted in the FW5&6 tanks compared to the FW1&2 and FW3&4 tanks. Removal of Cu, Cd, As from the supernatent waters as well as slow removal rates of the elements (including Hg) are likely due to the combining of the elements with organic ligands on the suspended particles and subsequent removal to the bottom sediments. Fast removal rates of the metal ions (Cu, Cd, As) and rapid increase of phosphate concentrations in the SW1&2 tanks are possibly due to the relatively porous anoxic sediments in the SW1&2 tanks compared to those in the SW3&4 tanks, efficient supply of phosphate and hydrogen sulfide ions in pore wates to the upper water body, complexing of the metal ions with the sulfide ions, and subsequent removal to the bottom sediments. Organic materials on the particles and sulfide ions from the pore waters are the major factors constraining the behaviors of organic/inorganic elements in the supernatent waters of the experimental tanks. This study needs more consideration on more diverse organic and inorganic elements and experimental conditions such as tidal action, temperature variation, activities of benthic animals, etc.

• Food Science of Animal Resources
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• v.29 no.4
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• pp.445-456
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• 2009

Colostrum samples were collected from 36 dairy farms in Gyeonggi-do and one dairy farm in the National Institute of Animal Science (NIAS) for testing. Colostrum samples were analyzed for phisycochemicals (specific gravity, pH, titratable acidity), general components (fat, protein, lactose, total solid, solid non-fat (SNF)), fatty acids, amino acids, minerals, microflora, somatic cells, and Ig (Immunoglobulin). The first colostrum revealed the following data: fat contents were $6.16{\pm}2.39%$, proteins were $14.78{\pm}4.30%$, lactose $2.57{\pm}0.77%$, total solid $24.28{\pm}4.36%$, and SNF $18.12{\pm}4.08%$, whereas the 2nd (or $12^{th}$) colostrum revealed $5.56{\pm}1.76%$ fat, $3.46{\pm}0.41%$ proteins, $4.19{\pm}0.43%$ lactose, $13.90{\pm}1.76%$ total solid, and $8.34{\pm}0.81%$ SNF. Also, the first colostrum revealed the contents of major amino acids as 0.89% aspartic acid, 0.71% threonine, 0.86% serine, 1.75% glutamic acid, 0.64% valine, 0.95% leucine, 0.83% lysine, and 0.95% proline, and those in the 10th colostrum were 0.25% aspartic acid, 0.15% threonine, 0.19% serine, 0.59% glutamic acid, 0.19% valine, 0.35% leucine, 0.31% lysine, and 0.34% proine. Major amino acid contents rapidly decreased as milking times increased. In the first colostrum, the following mineral contents were observed: there were 2,168 ppm in Ca, 1,959 ppm in P, 914 ppm in K, 761 ppm in Na, 287 ppm in Mg, 1.7 ppm in Fe, 14.3 ppm in Zn, and 1.0 ppm in Cu; while in the 10th colostrum, the following ppm contents were 1,389 in Ca, 1,323 in P, 838 in K, 427 in Na, 131 in Mg, 1.0 in Fe, 4.7 in Zn, and 1.3 in Cu. The mineral contents in a colostrum rapidly decreased as milking times increased.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.341-347
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• 2008

The feasibility of commercializing the hydrothermal synthesis of Na-A type zeolite from siliceous mudstone has been conducted using a 50-liter bench-scale autoclave and the application of the zeolite as an environmental remediation agent. Siliceous mudstone, which is widely distributed around the Pohang area, was adopted as a precursor. The siliceous mudstone is favorable for the synthesis of zeolite because it contains 70.7% $SiO_2$ and 10.0% $Al_2O_3$, which are major ingredient of zeolite formation. The synthesis of zeolite was carried out under the following conditions that had been obtained from the previous laboratory-scale tests: 10hr reaction time, $80^{\circ}C$ reaction temperature, $Na_2O/SiO_2$ ratio = 0.6, $SiO_2/Al_2O_3$ ratio = 2.0 and $H_2O/Na_2O$ ratio= 98.6. The crystallinity and morphology of the zeolite formed were similar to those obtained from the laboratory-scale tests. The recovery and cation exchange ion capacity were 95% and 215 cmol/kg, respectively, which are slightly higher than those obtained in laboratory scale tests. To examine the feasibility of the zeolite as an environmental remediation agent, experiments for heavy metal adsorption to zeolite were conducted. Its removal efficiencies of heavy metals in simulated waste solutions decreased in the following sequences: Pb > Cd > Cu = Zn > Mn. In a solution of 1500 mg/L total impurity metals, the removal efficiencies for these impurity metals were near completion (> 99%) except for Mn whose efficiency was 98%. Therefore, the synthetic Na-A type zeolite was proven to be a strong absorbent effective for removing heavy metals.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.4
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• pp.517-524
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• 2009

We collected 177 fishes representing 53 species of fish from the eastern (Pohang), western (Gunsan), and southern (Tongyeong) coasts of Korea, and measured their heavy metal contents. The mean recoveries of the heavy metals extracted from cod muscle (certified reference material, CRM) were $88.7{\sim}100.6%$. The mean levels of the heavy metals in the samples taken from the edible portion of each fish were high in the order of Zn ($8.981{\pm}4.835{\mu}g/g$), Cu ($0.755{\pm}0.507{\mu}g/g$), and Mn ($0.433{\pm}0.699{\mu}g/g$), which are necessary metals in the human body, and then followed by Cr ($0.206{\pm}0.181{\mu}g/g$), Ni ($0.081{\pm}0.110{\mu}g/g$), Pb ($0.038{\pm}0.046{\mu}g/g$), Cd ($0.017{\pm}0.023{\mu}g/g$). The average daily intakes of the heavy metals by the fishes were as follows: Cd (0.81 ${\mu}g$), Cr (9.98 ${\mu}g$), Cu (36.63 ${\mu}g$), Mn (21.01 ${\mu}g$), Ni (3.93 ${\mu}g$), Pb (1.84 ${\mu}g$) and Zn (435.58 ${\mu}g$). The average weekly intakes of Cd, Cu, Pb and Zn by the fishes were 1.35%, 0.12%, 0.86%, and 0.73% respectively, as compared with PTWI (Provisional Tolerable Weekly Intakes) established by FAO/WHO Expert Committee for Food Safety Evaluation.

• Korean Journal of Microbiology
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• v.37 no.3
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• pp.197-203
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• 2001

An ubiquitous bacterium, Pseudomonar cepacia KH410 was isolated from fresh water plant root and identified. Adsorption of heavy metals of lead, cadmium and copper by this strain was investigated. Optimal conditions foradsorption was 1.0 dry g-biomass, at pH 4.0 and temperature of $40^{\circ}C$. Adsorption equilibrium reached max-imum after 120 min in 1000 mg/l metal solutions. The adsorption capacity (K) of lead was 5.6 times higher thancadmium and 4.0 times higher than that of copper. Adsorption of lead was applicable for Langmuir modelwhereas Freundlich model for cadmium and copper, respectively. Adsorption strength (1/n) of heavy metal ionswere in the order of lead>copper>cadmium. Uptake capacity of lead, cadmium and copper by dried cell was83.2,42.0,65.2 mg/g-biomass, respectively. Effective desorption was induced 0.1 M HCI for lead and 0.1 $HNO_3$ for cadmium and copper. Pretreatment to increase ion strength was the most effective with 0.1 M KOH.Uptake by immobilized cell was 77.8,58.5,71.2 mg/g-biomass for lead, cadmium and copper, respectively. Theimmobilized cell was more effective than ion exchange resin on removal of heavy metals in solution containinglight metals.

• Journal of Energy Engineering
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• v.22 no.2
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• pp.237-244
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• 2013

The engine oil is used for lubrication of various internal combustion engines. Recently, the vehicle and engine oil manufacture usually guarantee for oil change over 15000~20000 km mileage, but the most of driver usually change engine oil every 5000 km driving in korea. It can cause to raise environmental contamination by used engine oil and increase the cost of driving by frequently oil change. In this study, we investigate the various physical properties such as flash point, pour point, kinematic viscosity, cold cranking simulator characteristics, total acid number, four-ball test and concentration of metal component for fresh engine oil and used engine oil after real vehicle driving (5000 km, 10000 km). The result showed that the total acid number, wear scar diameter by four-ball test, Fe and Cu had increased than fresh engine oil, but 2 kind of used oil (5000 km and 10000km) had similar physical values and concentration of metal component.