• Journal of Korean Society on Water Environment
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• v.31 no.4
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• pp.387-391
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• 2015

This study was performed to evaluate the effect of pH (8-12) and molar ratio of magnesium and phosphate ($[Mg^{2+}]/[PO_4{^{3-}}]$) (0.6-1.4) on struvite crystallization of anaerobic digester supernatant using seawater as magnesium source. pH range of 9-10 is favorable for ammonium and phosphate recoveries. The recovery efficiency of ammonium was highest at $[Mg^{2+}]/[PO_4{^{3-}}]$ of 1.0 and pH 10. On the other hand, high phosphate recovery efficiency (> 99%) was achieved at ($[Mg^{2+}]/[PO_4{^{3-}}]$) of 1.4 and pH 10. The results demonstrated that seawater can be considered as low-cost magnesium source to recover phosphorus from anaerobic digester supernatant.

• Journal of Korean Society on Water Environment
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• v.31 no.5
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• pp.576-582
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• 2015

In recently, the Korea government is concerning on non-point source pollution management to improve water quality. The objective of this paper is to investigate the improvement measurement for management of livestock wastes. As a result, we find that the National Pollution Source Survey is necessary to establish the unified database system with the Korea Statistics(KOSAT) in order to minimize the difference between relevant data. The investigation for environmental impact of livestock manure should be supported the designation of control areas and establishment of the technical guidelines including target material, monitoring site, standard method, etc. In addition, it should be followed by appropriate nutrient recycling and proper fertilizer usage based on social consultation and cost-benefit analysis.

• Journal of Korean Society on Water Environment
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• v.27 no.1
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• pp.30-35
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• 2011

2D pollutant transport model was applied to the simulation of contaminant transport in the channel. At first, two kinds of virtual channels having different slopes were designed. The distribution of contaminant, which flows from one of the three drainages to the main channel, was simulated by each 2D model. Concentrations of 745 nodes were converted to input data of neural network model (Multi-perceptron) for training and verification using matrix. The first three cases (Case A-1, A-2, A-3) were used for training Multi-perceptron, the other three cases (Case B-1, B-2, B-3) were used for verification. As a result, Multi-perceptron reasonably divided the cases into the three characteristics which have different contaminant distributions due to the different input point of water pollution source. It can be a useful methodology for the water quality monitoring and backtracking.

• International Journal of Advanced Culture Technology
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• v.9 no.1
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• pp.203-209
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• 2021

When carrying out computer programming, the process of checking and correcting errors in the source code is essential work for the completion of the program. Non-computer majors who are learning programming for the first time receive feedback from instructors to correct errors that occur when writing the source code. However, in a learning environment where the time for the learner to practice alone is long, such as an online learning environment, the learner starts to feel many difficulties in solving program errors by himself/herself. Therefore, training on how to check and correct errors after writing the program source code is necessary. In this paper, various types of errors that can occur in a Python program were described, the errors were classified into simple errors and complex errors according to the characteristics of the errors, and the distributions of errors by Python grammar category were analyzed. In addition, a coding learning process to refer error lists was designed to present a coding learning method that enables learners to solve program errors by themselves.

• Journal of Environmental Science International
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• v.19 no.12
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• pp.1421-1430
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• 2010

Polycyclic aromatic hydrocarbons (PAHs) were investigated in seawater and marine sediment from Anmyundo coastal area after oil spill. The concentrations of total PAHs in surface and bottom of seawater at August were 31.1 to 142.6 ng/L and 5.9 to 50.9 ng/L in August and November, respectively. The concentrations of PAHs in sediment were 21.0 to 102.9 ng/g D.W. and 32.3 to 57.4 ng/g D.W. in August and November, respectively. PAHs concentrations in seawater and sediment in August were higher than those in November about 2.5 and 1.4 times, respectively. Diagnostic ratio (PhA/AnT and FluA/Pyr) were investigated to identify source of PAHs in seawater and sediment. The PAHs in seawater originated from pyrolytic source and those in sediment originated from pyrolytic and petrogenic source. The glass, wood and coal origin was higher than petroleum origin on the combustion origin of PAHs in seawater and sediment. The seawater of Anmyundo costal area recovered from oil spill, but the sediments of that were weakly influenced by oil spill until now. Because this area is developed many fishing grounds, demanded Long Term Environmental Monitoring Program (LTEMP). The concentrations of PAHs on depth of sediments were investigated at station 8 and 10. The concentrations of PAHs were decreased with increasing depth.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.2
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• pp.179-189
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• 2006

Ambient gas phase mercury concentrations including elemental mercury ($Hg^0$) were measured at the Potsdam, Stockton, and Sterling sites in NY from 2000 to 2003. Also, concentrations of ambient reactive gaseous mercury (RGM; $Hg^{2+}$) were measured at the Potsdam site during one year. The contribution of RGM($4.2{\pm}6.4pg/m^3$) was about $0.2{\sim}3%$ of the total gas phase mercury concentration measured (TGM: $1.84{\pm}1.24,\;1.83{\pm}0.32,\;3.02{\pm}2.14ng/m^3$ in Potsdam. Stockton, and Sterling, respectively) at the receptor sites. Potential Source Contribution Function (PSCF), a hybrid receptor modeling incorporating backward trajectories was performed to identify source areas of TGM. Using PSCF, southern New York, North Carolina, and eastern Massachusetts were identified as important source areas in the United States, while the copper smelters and waste incinerators located in eastern Quebec and Ontario were determined to be significant sources in Canada. The Atlantic Ocean was suggested to be a possible mercury source. PSCF incorporating back-dispersion and deposition was applied for RGM , as well as PSCF based on 2-days back-trajectories. Two different approaches yielded considerably different results, primarily due to the consideration of dispersion rather than deposition. Using back-trajectory based PSCF, eastern Ohio, southern New York, and southern Pennsylvania where large coal -fired power plants area located were identified as the large sources in US. Metallurgical industry located in eastern Quebec was resolved as well. From the result of back-dispersion and deposition based PSCF, Pennsylvania, mining facilities around Lake Superior, Toronto, Boston, MA, Quebec, and coal power plants in NY were identified to be the significant source areas for Potsdam site.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.4
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• pp.128-135
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• 2005

This study was done to improve the effectiveness of nitrification and denitrification using the aeration-anoxic combination method using CFSTR(continuous-flow stirred-tank reactor) attached with an anoxic reactor filled with a media. In order to calculate the concentration of nitric acid within the aeration tank proportional to the anoxic rate within the reactor, supernatant within the inflow and precipitation tanks were influxed into the anoxic reactor. The rate of nitrogen removal was calculated using the concentration of inflow and flow of returned supernatant. From the results of this experiment, the carbon source needed in the anoxic reactor came from the inflow so that anoxification was achieved completely using the inflow source without the introduction of an external carbon source. However, as the ratio of nitric acid becomes large in inflow and nitric acid flow, the carbon source within the input source decreases so that the concentration of carbon source is important.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.657-663
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• 2004

The aims of this study are the characterization of runoff from nonpoint source, the analysis of the pollutant loads and an establishment of a management plan for nonpoint source of Okcheon. For this purpose the basin of the stream So-okcheon was selected to the investigated. During the period from May 29 to July 21 in 2003, the water automatic sampler system has been installed in Okkagkyo and parameters such as SS, COD, TOC, TP and TN were analyzed. The pollutants of nonpoint source seem to be washed out along the stream water in the beginning of rainfall, remain in water and cause the stream pollution. The runoffs during heavy rainfall, especially, much higher concentration of SS than those during dry period. With respect to the annual loading of pollutants of the nonpoint source, the COD was 124 ton/yr, TOC 396 ton/yr, TN 1,429 ton/yr and TP 4.2 ton/yr in the year 2002. With respect to the pollutants loading of the nonpoint source, the COD was 375 ton/yr(95% of the total COD loading of 394 ton/yr), TOC 844 ton/yr(96% of the tatal TOC loading of 876 ton/yr), TN 1,985 ton/yr(96% of the total TN loading of 2,062 ton/yr) and TP 37.1 ton/yr(92% of the total TP loading of 40.3 ton/yr) in the year 2003.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2007.10a
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• pp.418-419
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• 2007

• Korean Journal of Ecology and Environment
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• v.38 no.spc
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• pp.67-75
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• 2005

The objectives of this study were to understand the runoff characteristics of the non-point sources originating from impervious surfaces and to assess their effect on the aquatic environment in the urban areas. The concentration of pollutants (SS, BOD, COD and T-P) except for T-N showed the highest value in runoff from road, and event mean concentration (EMC) also showed high value from road. The pollutants discharged from road showed a higher concentration in the beginning stage (0 ${\sim}$ 30%) of progressive percentage of rainfall. The contribution percentages of non-point sources by load were 44.9% for SS, 11.2% for BOD, 21.4% for COD, 11.4% for T-N and 8.1% for T-P in the total load of pollutant discharged through sewer. From our results, the road was a significant potential source that deteriorated water quality of the streams and lakes in the vicinity of the urban area during the rain period. Therefore, counter plan is required to reduce pollutant concentration on the road from non-point sources in the urban area. Also, since pollutant concentration in the beginning stage of rainfall was quite high, road cleaning seems to be one of the very useful methods to prevent inflowing of pollutants to the aquatic environment.