• KSBB Journal
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• v.14 no.1
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• pp.76-81
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• 1999

Characteristics and oxidizing ability of both $NH_4-N$ and$NO^2$-N were examined for the strains isolated from wastewater treatment facilities and from natural systems by using Winogradsky columns. In case of $NH_4$-N, the most efficient strain was Nitrosomonas KB1 isolated from wastewater treatment facility of K corporation and in case of $NO_2$-N, it was Nitrobacter KB2 from the same site as Nitrosomonas KB1. For Nitrosomonas KB1, 91% of $NH_4$-N was oxidized after 4 days of cultivation. Optimal growth temperature and initial pH of Nitrosomonas KB1 were $28^{\circ}C$ and 7, respectively. In comparison to oxidizing rates with changing initial concentration of $NH_4$-N, the ammonia oxidizing rate was increased up to 6.7 mg/day for the initial $NO_2$-N concentrations for the region lower than 100 mg $NH_4-N/L$, but it was gradually reduced for the region higher than 100 mg $NH_4-N/L$. For Nitrobacter KB2 90% of $NO_2$-N was removed after culturing for 4 days. Optimal growth temperature and initial pH of Nitrobacter KB2 was $28^{\circ}C$ and 7, respectively. And the nitrite oxidizing rate was increased in proportion to the initial concentrations of $NO_2$-N up to 200 mg/$\ell$, and it was maintained almost 4.2 mg/day irrespective of initial $NO_2$-N higher than 200 mg/L.

• Korean Journal of Food Science and Technology
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• v.9 no.2
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• pp.157-164
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• 1977

In the present study, the proxidant effect of ferrous and cupric chlorides which added to soybean oil and its fried noodle in the same concentration of the city water and the physically refined underground water were determined. As the inhibitor of metal proxidation, BHA and citric acid which are used widely in oil industry as antioxidants were compared. In both cases of soybean oil and its fried noodle, the addition of cupric chloride and ferrous chloride showed prominent proxidant effect. Especially, cupric chloride marked more proxidant effect than ferrous chloride by 3 to 6 times with the elapse of time. In the inhibition activity of metal proxidation, citric acid was more effective than BHA. The 1ppm of Cu +0.01% of citric acid treated soybean oil showed less proxidant effect than the control at the later stage. The inhibition activity of citric acid on $Fe^{++}$ in soybean oil was more effective than $Cu^{++}$ in soybean oil.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.533-542
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• 2010

The $PM_{10}$ concentrations in the underground should be monitored for the health of commuters on the underground subway system. Seoul Metro and Seoul Metropolitan Rapid Transit Corporation are measuring several air pollutants regularly. As for the measurement of $PM_{10}$ concentrations, instruments based on $\beta$-ray absorption method and gravimetric methods are being used. But the instruments using gravimetric method give us 20-hour-average data and the $\beta$-ray instruments can measure the $PM_{10}$ concentration every one hour. In order to keep the $PM_{10}$ concentrations under a healthy condition, the air quality of the underground platform and tunnels should be monitored and controlled continuously. The $PM_{10}$ instruments using light scattering method can measure the $PM_{10}$ concentrations every less than one minute. However, the reliability of the instruments using light scattering method is still not proved. The purpose of this work is to study the reliability of the instruments using light scattering method to measure the $PM_{10}$ concentrations continuously in the underground platforms. One instrument using $\beta$-ray absorption method and two different instruments using light scattering method (LSM1, LSM2) were placed at the platform of the Jegi station of Seoul metro line Number 1 for 10 days. The correlation between the $\beta$-ray instrument and the LSM2 ($r^2$=0.732) was higher than that between the $\beta$-ray instrument and the LSM1 ($r^2$=0.393). Thus the LSM2 was chosen for further analysis. Three different regression analysis methods were tested: Linear regression analysis, Nonlinear regression analysis and Orthogonal regression analysis. When the instruments using light scattering method were used, the data measured these instruments have to be converted to actual $PM_{10}$ concentrations using some factors. With these analyses, the factors could be calculated successfully as linear and nonlinear forms with respect to the data. And the orthogonal regression analysis was performed better than the ordinary least squares method by 28.45% reduction of RMSE. These findings propose that the instruments using light scattering method light scattering method can be used to measure and control the $PM_{10}$ concentrations of the underground subway stations.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.525-532
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• 2014

Since mine wastes were merely dumped in the mine waste dump, they have produced acid mine drainage (AMD). Therefore, main objective of this study was to evaluate the effect of coal combustion products (CCPs) on heavy metal stabilization and detoxification for mine wastes. Total six treatments for incubation test were conducted depending on mixing method (completely mixing and layered). Also, lysimeter experiment was conducted to examine efficiency of polyacrylamide (PAM) on reduction of mine wastes erosion. Result of incubation test showed that concentrations of soluble aluminium (Al) and iron (Fe) in leachate decreased compared to control. The lowest soluble Al and Fe in leachate was observed in 50% mixed treatment (14.2 and $1.03mg\;kg^{-1}$ for Al and Fe respectively) compared to control treatment (253.0 for Al and $52.6mg\;kg^{-1}$ for Fe). The pH of mine wastes (MW) and leachate increased compared to control after mixing with CCPs and ordered as control (MW 6.4, leachate 6.3) < 10% (MW 7.7, leachate 7.1) < 20% (MW 9.0, leachate 7.8) < 30% (MW 9.5, leachate 8.3) < 40% (MW 9.9, leachate 8.5) < 50% (MW 10.5, leachate 8.6). Application of PAM, both in liquid and granular type, dramatically decreased the suspended solid (SS) concentration of CCPs treatments. Reduction of SS loss was ordered as MW70CR30L ($24.4mg\;L^{-1}$) > MW70CR30LPL ($6.7mg\;L^{-1}$) > NT ($3.1mg\;L^{-1}$) > MW70CR30M ($1.6mg\;L^{-1}$) > MW70CR30MPL ($1.1mg\;L^{-1}$) > MW70CR30PGM ($0.7mg\;L^{-1}$) > MW70CR30LPG ($0.5mg\;L^{-1}$) > MW70CR30MPG ($0.4mg\;L^{-1}$). Overall, application of CCPs can be environmental friendly and cost-effective way to remediate coal mine wastes contaminated with heavy metals. In addition, use of PAM could help to prevent the erosion coal mine wastes in mine waste disposal area.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.345-352
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• 2010

The objective of this paper is to explore the short-term variability of water temperature and chlorophyll a (Chl-a) derived from in-situ and satellite data (NOAA, Sea WiFS and QuikScat) in the upwelling region of the southeastern part of Korean Peninsula in June and August, 2007. Particularly we focused on the spatial variability of sea surface temperature(SST) and Chl-a in the East Korean Warm Current region. In the results of the in-situ data, the peaks of Chl-a in june was shown at a depth of 50m The peaks of Chl-a in August was shown at a depth of 10m at the stations 4 and 5 near the land, and a depth of 30m at the other stations. The Chl-a concentrations in August were also lower than those in june except for station 5. As a result, the peaks of Chl-a in August occurred at a depth of 20~40 m shallower than those of Chl-a in june. This indicates that the nutrient-rich water within the mixed layer depth may be immediately supplied by the coastal upwelling, which is due to the southerly component of wind. The relationship between SST and Chl-a showed a negative correlation, and the high concentration of Chl-a occurred in the cold water area. The southerly wind and the East Korean Warm Current influenced a remarkable offshore movement of the cold water and Chl-a near the coastal area.

• The Korean Journal of Financial Management
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• v.25 no.1
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• pp.141-176
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• 2008

This study provides an analysis of ex post efficient outcome, which can be said an objective of distressed restructurings, using the stock return of listed companies. The findings of this study are as follows: First, upon completing the distressed restructurings, reorganization and workout cases showed positive announcement effects, which was statistically significant. Also, composition cases displayed a positive value, but it was not statistically significant. Second, with respect to post-restructuring long-run stock performance, reorganization and composition showed underperformance after completion. However, workout cases showed overperformance after the completion. Third, multiple regression analysis to find factors affecting post-restructuring long-run stock performance suggests that higher asset decrease(ASSETCH), shareholder concentration (OWNCEN), largest shareholders' stake(OWN) have more positive impacts on long-run performance. However, change of the largest shareholder(OWNERCH) has negative impacts on long-run performance. Finally, change of the largest shareholder is a negative factor in the performance of the distressed restructurings. Therefore, this study implies that if M&A is used as a way of early completing the distressed restructurings, prudent judgment is required on whether a firm can recover its competitiveness and is likely to be economically viable again.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.138-144
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• 2006

Algal growth potential test (AGPT) has been used as a tool for assessing biological productivity potential in the aquatic ecosystems. This study was conducted to compare the productivity potentials of large reservoirs (Lakes Andong, Hapchon and Jinyang, and Naktong estuarine dam) and river sites (Sangju, Koryung, and Samlangjin) located in the Naktong River watershed. AGPT was conducted in both non-monsoon and mosoon season (February, April, July and September) of 2003, using Microcystis aeruginosa as a test alga. The AGPs in the reservoirs were relatively much lower than those of river sites. The river AGPs increased towards upstream close to the influent streams, while it generally decreased towards downstream. Immediately after the abrupt increase in influent discharge in summer, the AGP became similar between midstream and downstream sites. The water quality of river and reservoirs deteriorated during the drought period in accordance with AGP: it was the highest during this period. The AGPs showed the closest correlation with the P concentration, leading to the conclusion that bioavailable P is highly influential to the algal growth in both lentic and lotic ecosystems in the Naktong River watershed. Based on the AGPs, the water quality of tested sites was likely eutrophic. Our results suggest that AGPT be a useful tool in evaluating the productivity potential and trophic state of the water body as well as determining the nutrients that limit the growth of algae.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.407-414
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• 1999

Distribution of biota and removal efficiency of organic matter in natural wetland systems were examined from June to October 1998. The aquatic macrophyte communities were consisted of 13 families and 22 species. The composition of occurrence species were as follows: Phragmites communis Trinius are 35%, Persicaria thunbergii Nakai are 19%, Typha angustifolia L. are 17%, Bidens tripartita L. are 16%, Echinochloa crus-galli (L.) Beauv. are 12% and others are l％. The fauna collected from 5 sites consisted of total 6 classes of macroinvertebrates. The composition of occurrence classes were as follows: Insecta are 76%, O1igochaeta are 19%, Gastrapoda are 4％ and others are 1%. These included 18 families, 7 orders of Insects. The larve and mosquito and midges were found in wetlands. Preventive strategies are needed for the suppression of mosquito at the stage of wetland planning and design. In wetland, removal efficiency of dissolved organic carbon is low because of primary production and the background level of DOC in the wetland discharge seems to be 5 mgC/1, but those of BOD was ca. 50%. Wetlands receiving water of low concentration can not work as purification field.

• Journal of Environmental Impact Assessment
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• v.16 no.2
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• pp.143-156
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• 2007

This study has researched the management status and the pollution level of water, soil, stream sediments of 11 abandoned coal mines out of a total of 12 within Obong-Dam area except Bukyung mine, which was submerged when constructing Obong-Dam, and selected areas which are in needs to have pollution control facilities in the first place. From the results of examination on the runoff at the waste rock pile and mineheads, the runoff from Sueun mine (pH, Fe, Al), Samwon mine (pH, Al), Wangdo mine (pH, Al), Mose mine (pH, Fe, Al) and Daeryeong mine (pH) exceeded the permissible discharge standards of the water quality, but the water at merging point with Obong-Dam after joined with Doma branch satisfied both Water Quality Standards and Drinking Water Quality Standards. In regard to groundwater contamination, it is found that areas where exceeded the Drinking Water Quality Standards are Wangdo mine (pH), Jangjae mine (pH, Zn), Daeryeong mine (pH) whereas all areas satisfied Soil Contamination Warning Standards of Soil Environmental Conservation Law. When comparing a research result on underwater sediments of branches of abandoned mines to the EPA Guidelines for classification of great lakes harbor sediments, Dongguk Gaerim (Fe), Jungwon mine (Fe), Daebo mine (Mn), Samwon mine (Mn) and Daeryeong mine (Mn) showed mid-level of contamination, whereas Sueun (Fe, Mn), Daebo mine (Fe), Woosung mine (Fe, Mn), Wangdo mine (Fe, Mn), Mose mine (Fe) and Daeryeong mine (Fe) showed high-level of contamination. In addition, contamination levels of underwater sediments in Wangsan and Doma branch where abandoned mine's branches merge together, Wangsan branch showed no contamination at all whereas Doma branch shows mid-level of contamination which reflect the Doma branch is affected by waste rock pile and minehead runoff of the abandoned mines in the Doma branch area. It is concluded that Mose mine and Sueun mine required treatment of acid mine drainage. and Wangdo, Jungwon, and Samwon mines were in need of mine tailing and erosion control work. The Samwon mine additionally required a control system for closed minehead runoff. Although the Samwon mine reached a high concentration of Al, Mn $Ca^{2+}$, $SO{_4}^{2-}$ in the runoff, the levels decreased after it was combined with a tributary. It has been concluded that after further monitoring of the cause of pollution, a preventive measure system may be needed to be built.

• Korean Journal of Food Science and Technology
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• v.39 no.3
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• pp.266-271
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• 2007

The pH, acidity, color, reducing sugar, total sugar, alcohol, and organoletic characteristics of Takju containing puffed rice powder (0, 25, 50 and 75%) were investigated during fermentation for 10 days. After drastic decrease at Day 1, the pH increased gradually until Day 5 and then tended to decrease after Day 6. A lower concentration of puffed rice powder resulted in a greater pH reduction (p<0.05). Acidity increased quickly with days, especially for the 0% after Day 6 (p<0.05). After a sudden rise at Day 1, the Hunter ‘L’ value tended to decrease with days of fermentation. At the same day, the 75% showed the lowest Hunter ‘L’ value, however, it had the highest Hunter ‘a’ value except on Days 0, 3 and 10 (p<0.05). After a rapid reduction in reducing sugar on Day 3, no differences were observed in the samples (p<0.05). The 75% tended to be higher in reducing sugar. Total sugar decreased rapidly at Day 2, and then either remained unchanged or decreased after Day 3. With the exception of Day 4, the 75% had higher amounts of total sugar than the others at the same day (p<0.05). The Highest alcohol contents [13.0-16.4% (v/v)] occurred on Day 6. Higher alcohol concentrations were observed with higher puffed rice powder (p<0.05). In the sensory evaluation, no differences were detected between the 0% and those with puffed rice powder added (p<0.05).