• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.170-176
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• 1998

Nitrogen and phosphorus loads from an agricultural watershed of the Yulmun-chon tributary in the Buk-Han River Basin were quantified based on total amounts of water stream flow. The water quality and soil loss were estimated. Levels of the stream were recorded automatically using the water level meter. The flow velocities, along with the cross-sectional areas of the riverbed, were measured to estimate total amounts of water flow at three monitoring sites in this tributary. Water samples were collected at nine sites with two weeks interval from May to August and analyzed for the water quality parameters. Amounts of soil loss were estimated by the USLE. The size of the Yulmunchon watershed was 3,210 ha, of which paddy and upland soil areas were composed about 41%. The total amounts of soil loss from the watershed areas were estimated to be $13,273Mg\;year^{-1}$, showing 53%, 46% and 0.7% of the soil loss ratio from upland, forest, and paddy areas, respectively. Electrical conductivities and Nitrogen concentrations of the stream water were higher in the lower watershed area than in the upper area. Increments of N were higher for $NO_3-N$ than $NH_4-N$. Nitrate nitrogen was the major N form to pollute the water due to the agricultural activity. Total runoff was about 72% of the total precipitation in the watershed. The maximum loads of T-N and T-P due to the runoff were estimated to be 1,500 and $5kg\;day^{-1}$, respectively. Concentrations of $NO_3-N$ and $NH_4-N$ in the runoff were 13.5 and 1.8 times higher than those in precipitation. The N loads were mainly from soil loss, application of fertilizer, and livestock wastes, which were 52% of total N load. Results demonstrated that reduction of fertilizer use and the soil loss would be essential for water quality protection of the agricultural watershed.

• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.279-286
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• 2005

Microbial contamination origin of Kimbab was determined using nine types of ready-to-use ingredients, three each from animal, seafood, and vegetable sources. Effect of radiation on microbiological safety was also investigated. Total aerobic bacteria were not detected in seasoned beef, ham, and seasoned burdock, whereas 3.50, 5.41, 8.83, and 5.07 log CFU/g were detected in surimi gel, seasoned and blanched spinach, dried laver, and cucumber, respectively. Total aerobic bacterial and mold numbers were 8.73 and 5.08 log CFU/g in prepared Kimbab. Gamma irradiation reduced level of contaminated aerobic bacteria and mold population in Kimbab and its ingredients, Salmonella mutagenicity assay (Ames test) showed Kimbub ingredients irradiated at 10 kGy did not show any mutagenicity. These results indicate ready-to-use kimbab ingredients were mostly responsible for total aerobic bacteria and mold population of Kimbab, and low dose irradiation and low temperature storage ($10^{\circ}C$) effectively ensured microbiological safety of Kimbab and ready-to-use ingredients.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.325-345
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• 2020

Determination of Best available technology (BAT) was suggested to reduce volatile organic compounds (VOCs) in a petrochemical industrial complex, by conducting human health risk, environmental, and economic assessment based on multimedia fugacity model. Fate and distribution of benzene, toluene, ethylbenzene, and xylene (BTEX) was predicted by the multimedia fugacity model, which represent VOCs emitted from the industrial complex in U-city. Media-integrated human health risk assessment and sensitivity analysis were conducted to predict the human health risk of BTEX and identify the critical variable which has adverse effects on human health. Besides, the environmental and economic assessment was conducted to determine the BAT for VOCs reduction. It is concluded that BTEX highly remained in soil media (60%, 61%, 64% and 63%), and xylene has remained as the highest proportion of BTEX in each environment media. From the candidates of BAT, the absorption was excluded due to its high human health risk. Moreover, it is identified that the half-life and exposure coefficient of each exposure route are highly correlated with human health risk by sensitivity analysis. In last, considering environmental and economic assessment, the regenerative thermal oxidation, the regenerative catalytic oxidation, the bio-filtration, the UV oxidation, and the activated carbon adsorption were determined as BAT for reducing VOCs in the petrochemical industrial complex. The suggested BAT determination methodology based on the media-integrated approach can contribute to the application of BAT into the workplace to efficiently manage the discharge facilities and operate an integrated environmental management system.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.32-42
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• 2008

A surfactant recovery and reuse process by selective adsorption with activated carbon was proposed to reduce surfactant cost in a soil washing process. Mathematical model simulation was performed for the whole process, which consists of soil washing, soil recovery, and soil re-washing. The optimal range of surfactant dosage was $6{\sim}10$-fold critical micelle concentration in soil. The efficiency of surfactant reuse process was decreased with increasing the dosage of activated carbon. Effectiveness factor for activated carbon significantly altered the efficiency of the reuse process unlike effectiveness factor for soil. Total requirement of surfactant was reduced to 20-30% with the reuse process compared to the conventional soil washing process. The contamination of wastewater after soil washing was reduced with the reuse process. This mathematical model can be used to estimate performance of the whole process of soil washing including surfactant recovery and to obtain optimal ranges of operating conditions without extra labor-intensive experimental works.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.4
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• pp.436-445
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• 2014

Objectives: Time-activity studies have become an integral part of comprehensive exposure assessment and personal exposure modeling. The aims of this study were to estimate exposure levels to nitrogen dioxide($NO_2$) and volatile organic compounds(VOCs), and to compare estimated exposures by using time-activity patterns and indoor air concentrations. Methods: The major microenvironments for office workers were selected using the Time-Use Survey conducted by the National Statistical Office in Korea in 2009. A total of 9,194 and 6,130 workers were recruited for weekdays and weekends, respectively, from the Time-Use Survey. It appears that workers were spending about 50% of their time in the house and about 30% of their time in other indoor areas during the weekdays. In addition, we analyzed the time-activity patterns of 20 office workers and indoor air concentrations in Daegu using a questionnaire and time-activity diary. Estimated exposures were compared with measured concentrations using the time-weighted average analysis of air pollutants. Conclusions: According to the time-activity pattern for the office workers, time spent in the residence indoors during the summer and winter have been shown as $11.12{\pm}2.20$ hours and $12.48{\pm}1.77$ hours, respectively, which indicates higher hours in the winter. Time spent in the office in the summer has been shown to be 1.5 hours higher than in the winter. The target pollutants demonstrate a positive correlation ($R^2=0.076{\sim}0.553$)in the personal exposure results derived from direct measurement and estimated personal exposure concentrations by applying the time activity pattern, as well as measured concentration of the partial environment to the TWA model. However, these correlations were not statistically significant. This may be explained by the difference being caused by other indoor environments, such as a bar, cafe, or diner.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.290-298
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• 2013

A Saemangeum Development Project, which is a national project in South Korea, has started with the objective of developing the reclaimed area mainly agricultural land use since the mid'80s. To develop a model of the global eco-reclamation, constructions of the eco-friendly counter facilities such as sluice gates and inner dikes, as well as environmental preservation measures for an estuary reservoir, have been carried out. However, reasonable measures of the water quality management for the Saemangeum area are required. Thus, the purpose of this study is to rigorously analyze and quantitatively evaluate the environmental problems due to the water level management associated with inner dike constructions. To achieve these objectives, the affecting factors on determination of water level management are described and a series of calibrated transient-state numerical simulations was performed to demonstrate the salinity distribution difference in the estuary before and after the construction of inner dikes. The overall salinity reduced about 2~5 psu, and the seawater intrusion was weakened by a well-regulated waterway after construction of the inner dikes compared to before construction of them.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1081-1089
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• 2005

In order to examine the application feasibility of Orimulsion fuel in a commercial boiler using heavy fuel oil, a numerical and experimental research efforts have been made especially to figure out the fundamental combustion characteristics of this fuel in a small-scale boiler. One of the notable combustion features of Orimulsion fuel is the delayed appearance of flame location with the flame shape of rather broad distribution, which is found experimentally and confirmed by numerical calculation. This kind of flame characteristics is considered due to the high moisture content included inherently in the process of Orimulsion manufacture together with micro-explosion by the existence of fine water droplets. In order to investigate the effect on the combustion characteristics of Orimulsion, a series of parametric investigation have been made in terms of important design and operational variables such as injected amount of fuel, types of atomization fluid, and phonemenological radiation model employed in the calculation, etc. The delayed feature of peak flame can be alleviated by the adjustment of the flow rate of injected fuel and the generating features of CO, $SO_2$ and NO gases are also evaluated in the boiler. When the steam injection as atomizing fluid is used, the combustion process is stabilized with the reduced region of high flame temperature. In general, the calculation results are physically acceptable and consistent but some refinements of phenomenological models are necessary for the better resolution of pollutant formation. From the results of this small-scale Orimulsion boiler, it is believed that a number of useful information are obtained with the working computer program for the near future application of Orimulsion fuel to a conventional boiler.

• Journal of Radiation Protection and Research
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• v.23 no.4
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• pp.219-227
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• 1998

A solution containing $^{85}Sr$, $^{103}Ru$ and $^{134}Cs$ was applied to Chinese cabbage in a greenhouse via foliar spraying at 5 different times during its growth. Interception of the applied activity by plant showed no difference among radionuclides and increased with decreasing time interval between application and harvest. The maximum interception factor observed was 0.87. Percentages of the intercepted activity remaining in the whole leaves at harvest varied $16{\sim}58%$ for $^{85}Sr$, $15{\sim}73%$ for $^{103}Ru$ and $33{\sim}64%$ for $^{134}Cs$, with application time and those for the inner leaves (without 6 outmost leaves) varied $2{\sim}35%$, $0.4{\sim}46%$ and $14{\sim}40%$, respectively. It was demonstrated that rain plays an important role in weathering loss of the activity. Tying the upper end of the plant prior to the last application lowered interception and remaining activity in the inner leaves by factors of $3{\sim}4$. Present results can be referred to in predicting the radionuclide concentration in Chinese cabbage and deciding counter-measures at the time of an accidental release from the nuclear installation.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.326-334
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• 2012

To determine the concentrations and the mass flow of selected 10 perfluorinated compounds (PFCs), a field study was conducted in a wastewater treatment plant. Raw influent, primary influent, primary effluent, aeration tank effluent, secondary effluent, final effluent, dehydration liquor, primary sludge, thickened sludge, final sludge were collected over 3 days in the summer and the winter respectively. Collected samples were equally mixed and then served as an analytical sample. Total 10 compounds were analyzed. In terms of treated water, the concentration of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) were in range of N.D.~26.29 ng/L and N.D.~38.15 ng/L respectively. Perfluorononanoate (PFNA) and perfluorohexanesulfonate (PFHxS) were ranged from N.D. to 36.79 ng/L and from N.D. to 24.36 ng/L. In terms of sludges, a concentration of PFOS, PFOA, and perfluorodecanesulfonate (PFDS) were detected from 6.82 to 59.37 ng/g, from 0.13 to 0.37 ng/g, from N.D. to 0.83 ng/g respectively. Mass loading for PFCs increased during wastewater treatment except for PFNA. The observed increase in mass flow of PFCs may have resulted from biodegradation of precursor compounds.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.771-778
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• 2008

Effects of establishments of more sewer systems on water quality in Nam River, Deokchun River, and Jinyang Lake were analyzed for various scenarios using QUAL2E, WASP 7 water quality model. Three different scenarios were tested: 1) 20.8% of sewer diffusion rate which is same to the existing condition. 2) Expansion of sewer system to 65.2% which would emit less pollutants, BOD 2350.5 kg/d, TN 216.0 kg/d, TP 44.0kg/d. 3) Pollutants emission to maintain first grade water quality in Nam River, Jinyang Lake, BOD and TN in the case 2 were 7.69%, 2.10% lower than those in the case 1 in the Nam River. And in the Jinyang Lake, BOD, TN, and TP in the case 2 were 10.25%, 1.37%, 2.94% lower than those in the case 1. However the simulations showed that water quality could not hold down first grade water quality standard level with the establishments of more sewer systems. To satisfy the criteria in the Nam River and Jinyang Lake, BOD emission must be reduced 27.2%, 37.05% compared to those in the case 1.