• Applied Chemistry for Engineering
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• v.24 no.1
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• pp.67-71
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• 2013

$FeCl_3$ has been used as an etchant for metal etching such as Fe, Cu, and Al. In the process of metal etching, $Fe^{3+}$ is reducted to $Fe^{2+}$ and the etching rate becomes slow and etching efficiency decreased. Waste $FeCl_3$ etchant needs to be regenerated because of its toxicity and treatment cost. In this work, HCl was initially mixed with the waste $FeCl_3$ and then, strong oxidants, such as $O_2$ and $H_2O_2$, were added into the mixed solution to regenerate the waste etchant. During successive etching and regeneration processes, oxygen-reduction potential (ORP) was continuously measured and the relationship between ORP and etching capability was investigated. Regenerated etchant using a two vol% HCl of the total etchant volume and a very small amount of $H_2O_2$ was very effective in recovering etching capability. During the etching-regeneration process, the same oxygen-reduction potential variation cannot be repeated every cycle since concentrations of $Fe^{2+}$ and $Fe^{3+}$ ions were continuously changed. It suggested that the control of etching-regeneration process based on the etching time becomes more efficient than that of the process based on oxygen reduction potential changes.

• Korean Journal of Ecology and Environment
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• v.33 no.1 s.89
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• pp.31-37
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• 2000

For the purpose of surveying the physicochemical composition of sediment collected from Kwangyang Bay, the percentage of water loss, COD, $H_2S$, grain size and 10 heavy metals were studied at 17 sites. During the surveying period, the changes of the percentage of water loss were appeared $35.5\;{\sim}\;53.8%$. COD and $H_2S$ were showed $3.8\l{\sim}\;12.9\;mg/g$, and $0.1\;{\sim}11.4\;{\mu}g/g$, respectively, In composition of grain size on the sediment, percentages of grain sizes under $74\;{\mu}m$ were varied from 40.5% to 86.7% and above $74\;{\mu}m$ were varied from 11.5% to 43.0%. From the spatial distribution of heavy metal using contour map, we can suppose some heavy metal discharges which affect sediment of Kwangyang Bay, It was estimated that Shinpung creek, Ssang-bong creek, and draining area of sewange treatment plant were the main discharge among the heavy metal output sources. By comparison between present study and heavy metal guideline of nonpolluted sea sediment that is provided by EPA, US, it was showed that the contents of Pb and Hg were acceptable but contents of Mn, Zn, Cu, Fe, As, and Cr were higher than those of EPA guideline.

• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.216-222
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• 2011

BACKGROUND: This study was performed to evaluate the effects of environmental factors and heavy metals on the growth and phosphorus removal capacity of Alcaligenes sp., which was well known as one of PAOs(Phosphorus Accumulating Microorganisms). METHODS AND RESULTS: The environmental factors used in this study were temperature, pH and carbon sources, and the heavy metals included Cu, Cd, Zn, As, and Ni. The growth and P removal efficiency of Alcaligenes sp. was maximal as temperature, pH, and carbon source were $25^{\circ}C$, 7, and glucose+acetate, respectively. Also, the $IC_{50}$(median inhibitory Concentration) values of Alcaligenes sp. for the Cu, Cd, Zn, As, and Ni were 5.03, 0.08, 0.73, 282.20 and 4.74 mg/L, respectively. CONCLUSION(S): Based on the results obtained from this study, it appears that the growth and P removal efficiency of Alcaligenes sp. were affected by the environment factors and at the best optimum condition for its growth and P removal efficiency, as the concentrations of heavy metals were gradually increased, its growth was correspondingly decreased.

• Korean Journal of Ecology and Environment
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• v.43 no.2
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• pp.255-262
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• 2010

This study was conducted at 5 sites of Bocheong Stream basin in May and September 2009 for the evaluate of fish assemblage and chemical water quality. For the study, the models of Index of Biological Integrity (IBI) and Qualitative Habitat Evaluation Index (QHEI) were modified as 8 and 11 metric attributes, respectively. We also analyzed patterns of chemical water quality at the sampling site over the period of 2005~2009, using the water chemistry dataset, obtained from the Ministry of Environment, Korea. The survey showed that total sampled fishes were 34 species and the most dominant species was Zacco platypus (24.3%). In Bocheong Stream basin, values of IBI averaged 28 (n=5), which is judged as a "Good". IBI score at B1, B4 and B5 indicating a "Good" condition whereas, B2 and B3 were as 21 and 22, indicating "Fair" condition, respectively. QHEI was 152 (n=5), judged as "Fair" habitat condition. Values of BOD and COD averaged 1.0 $mgL^{-1}$ (scope: 0.3~4.0 $mgL^{-1}$) and 2.3 $mgL^{-1}$ (scope: 0.3~18.7 $mgL^{-1}$), respectively. Total nitrogen (TN), total phosphorus (TP) and suspended solid (SS) were distinct spatial variation. Based on the IBI, QHEI and chemical water quality dataset, ecological health of Bocheong Stream basin was evaluated that generally good.

• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.112-121
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• 2015

In this study, Copper Azole (CuAz), a domestically available wood preservative for pressure treatment, was employed to perform an experimental research on its infiltration and decay properties in Japanese Red Pine. Test specimens were pressure-injected with CuAz-2 preservative to measure its preservative effectiveness, and then its impact on weight and mass losses. Furthermore, wood specimens were treated with CuAz-2 preservatives of various concentration levels before they were decayed with brown-rot-fungi in order to observe decay properties on light microscope (LM) and field emission scanning electron microscope (FE-SEM). As a result, untreated specimen by Fomitopsis palustris showed the mass loss of more than 40%, and the value of preservative effectiveness of CuAz-2 by indoor decay was $1,73-3.32kg/m^3$. The concentration levels of CuAz-2 preservative were shown to cause significant variations in terms of decay progresses in the cross section, radial section, and tangential section. By contrast, untreated specimens had underwent serious decays in early wood, late wood, longitudinal resin canals, and ray, which led to vertical destruction of wood texture. As for the radial section, ray tracheid, ray parenchyma cell, and window like pits were decayed and destroyed. In the case of tangential section, uniseriate rays and vertical resin canals were seriously decayed. In conclusion, this study indicates that the adequacy of the current CuAz injection amount should be reviewed in the domestic environment because there are significantly different decays at different decay conditions.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.21-28
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• 2018

The contents of total nitrogen, total phosphate, and total potash are important factors to determine the application rate of the organic fertilizers to arable lands. The concentrations of nutrient, organic matter, salt, water, heavy metal in mixed oil cakes and mixed organic fertilizers in circulation were investigated with 141 and 179, respectively. The mean levels of total nitrogen, total phosphate, and total potash in organic fertilizers of from 2015 to 2017 were 4.9%, 2.8%, 1.7%, respectively. The average contents of organic matter, salt, and water were 77.0%, 11.5%, and 0.3%, in mixed oil cakes, and 72.3%, 11.7%, 0.5% in mixed organic fertilizer, respectively. The maximum concentrations of Cr, Cu, Ni, and Zn were found to be in accordance with the official standard of commercial fertilizer. In order to promote balanced nutrient absorption of crops, it is necessary to increase the average content of total potash of the organic fertilizers to 3.2%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.14 no.2
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• pp.171-176
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• 1985

The effects of cooking methods by boiling, electric oven and microwave on the proximate composition, minerals and water-soluble vitamins of two major Korean potato varieties (Soomi and Namjac) were studied. The dry matter content was increased after the cooking by the methods of electric oven and microwave, however, the crude fiber content was highly decreased by both methods. The crude ash content was not affected by the cooking methods used. The potassium content was increased by electric oven and microwave methods, and iron content was increased by electric oven baking, however, the copper content was significantly decreased by the electric oven and microwave cooking methods. The macrominerals (phosphorus, magnesium, calcium) and microminerals (zinc, manganese, nickel, lead, cadmium) content present initially in potatoes have not been changed by the cooking methods employed in this study. Relative retention value of ascorbic acid was the lowest and the value of thiamin was the highest in the potatoes cooked by microwave. The retention values of riboflavin and folic acid obtained. after boiling were similar to those after microwave cooking, and both of these treatments were superior to the electric oven baking. The retention values of niacin and vitamin $B_6$ varied between 93 and 100% depending on the cooking methods used. Overall, with a few exceptions, the retention values of water-soluble vitamins in boiled and microwave cooked potatoes were superior to those of the electric oven baked.

• Geophysics and Geophysical Exploration
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• v.17 no.4
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• pp.247-252
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• 2014

Gagok Mine, which is skarn deposits, includes sulfide minerals such as sphalerite, galena, chalcopyrite, and pyrrhotite. To explore these minerals, spectral induced polarization (SIP) is relatively effective compared to other geophysical exploration methods because there is a strong IP effect caused by electrode polarization. In the SIP, the chargeability related to sulfide mineral contents and the time constant related to the grain size of the minerals are obtained. For this reason, we aim to compare difference in the mineralized characteristics between two orebodies in the Gagok Mine by using the chargeability and the time constant. For this study, we sampled ores from the south of Wolgok orebody and the north of Sungok orebody. In order to recognize the mineralization characteristics, the metal content of the samples was measured by a potable XRF and the SIP data of the samples were acquired by using a laboratory SIP measurement system. As a result, the metals in the samples such as Pb, Zn, Cu, and Fe were detected by the portable XRF measurement. In particular, the Fe and Zn contents were far higher than the other metals. The Fe and the Zn were caused by the sphalerite and the pyrrhotite through microscopy. The Wolgok orebody had higher sulfide mineral contents than the Sungok orebody and the result corresponded with the chargeability result. However, we considered that the Sungok orebody had a larger sulfide mineral grain size than the Wolgok orebody because the time constant of the Sungok orebody was larger.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.10
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• pp.1195-1204
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• 2017

This study was designed to determine the effects of three cooking methods, boiling, microwave, and steaming, on elemental compositions of green pumpkin, zucchini, and sweet and ripened pumpkin. The cooking methods were carried out at 3, 5, and 10 min. The samples were then dried, crushed, and decomposed by microwave-assisted digestion method. Macro elements were analyzed by Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES), whereas ICP-Mass Spectrometer (ICP-MS) was used for micro elements determination. From the results, macro elements were present in the order of K, P, Ca, Mg, S, Fe, Zn, and Na in all analyzed pumpkins. Among micro elements, Mn, Cu, Rb, and Ba, were present at high levels. For the effects of cooking methods, boiling significantly reduced the concentrations of elements. Cooking time affected concentrations of elements in the same manner with large differences between elemental contents in samples cooked for 5 and 10 min. Regarding micro elements contents, both effects were not significant. Similar elemental compositions with different concentration levels in all pumpkin types were observed. Green pumpkin and ripened pumpkin showed high retention rates of inorganic components upon steaming, and zucchini and sweet pumpkin showed high retention rates upon microwave cooking. Conclusively, cooking method and time affect amounts of residual inorganic ingredients in pumpkin.

• Food Science and Preservation
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• v.21 no.4
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• pp.473-482
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• 2014

Changes in quality of mushroom during storage are severe problem that reduce the shelf life of harvested mushrooms. This study investigates the effect of oriental melon peel extracts on maintenance of the quality of mushrooms (Agaricus bisporus). Mushrooms were dipped in solutions (distilled water, DW; 0.1% oriental melon peel extract, OMP; 0.1% ascorbic acid, AA; and OMP+AA) for 3 minutes. After the dipped mushrooms were air-dried at room temperature, they were packaged in a polypropylene (PP) films and stored at $4^{\circ}C$ and $15^{\circ}C$. The changes in the quality of mushrooms were measured in terms of their color, gas composition, firmness, and sensory evaluation during storage at $4^{\circ}C$ and $15^{\circ}C$. The antioxidant and anti-browning activities of oriental melon peel extract were measured with respect to their total polyphenol contents, total flavonoid contents, DPPH, ABTS radical scavenging, copper chelating activity and PPO inhibition activity. The samples that were dipped in all the solutions did not show significant differences in firmness and gas exchange during their storage at $4^{\circ}C$ and $15^{\circ}C$. At both storage temperatures, the OMP solution samples showed highest L value and lowest delta E value. The sensory evaluation showed that during the storage period, the overall acceptability of mushrooms treated with the OMP and OMP+AA solutions was higher than that of the untreated mushrooms. The total polyphenol and flavonoid contents of oriental melon peel extract were $4.81mg\;GAE{\cdot}g^{-1}$ and $1.18mg\;QE{\cdot}g^{-1}$, respectively. The DPPH, ABTS radical scavenging activity, copper chelating activity and PPO inhibition activity of the oriental melon peel extract lower than ascorbic acid. All these results suggest that oriental melon peel extract can be used as a natural browning inhibitor.