• Journal of Korea Water Resources Association
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• v.52 no.12
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• pp.1047-1055
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• 2019

Various types of numerical modeling techniques are used to predict the behavior of pollutants under various water environmental conditions in the event of a water pollutant accident. Among them, a hydraulic model that can consider water flow characteristics is the most basic and very important. The process of evaluating whether the hydraulic model accurately predicts the applied river characteristics is very important. In the verification of the modeling result, the measuring data are often used in the river. Currently, ADCP and FlowTrackers are widely used to measure the flow velocity of rivers. However, ADCP is not accurate when the depth is less than 0.6 m and also when the ratio of irreversibility near the surface is more than 40%. Futhermore, FlowTracker has a limitation in measuring at high depth and high velocity due to the direct measurement method in rivers. Simuation results, which are validated by these methods, are not reliable for low depth conditions of low flowrate and high velocity conditions of high flowrate. In this study, Lagrangian GPS floaters which measures physical quantity of water according to particle movement is used without the conventional method measured by Eulerian technique. The verification method of the model results was studied by comparing the simulation results of the hydraulic model with the velocities measured using the GPS floaters. When comparing the traveling distance of the GPS floaters with the traveling distance of the LPT simulations, the average error rate was 13.6% on distances, and the average error rate was 3.2% on velocities except for the stagnant section. Therefore, GPS floaters can be used for a correction and verification method of hydraulic model simulations.

• Journal of radiological science and technology
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• v.38 no.3
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• pp.305-313
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• 2015

After Fukushima Daiichi nuclear disaster in 2011, study and maintenance of monitoring systems have been made at home and abroad. As concerns about radioactive contamination of water have increased in Korea, update of maintenance of managing radioactive materials in water is being made mainly by Ministry of Environment. In this study, we analysed current state of monitoring system modification in Japan, the country directly involved and neighboring country. According to the result, Japan modified the legislations first. Then Ministry of Education, Culture, Sports, Science and Technology (MEXT) provides theoretical background of radiological monitoring. And Ministry of the Environment actually watches state of water pollution in public waters and underground water. Finally related agencies like local government are monitoring current state of radioactive contamination in water environment. By region, local monitoring stations share the investigation of the whole country. Also, additional monitoring is running around nuclear facilities. After Fukushima disaster, monitoring for area near Fukushima is added. Among the reference levels, management target value of drinking water and tap water is 10 Bq/kg, and those of public water and underground water are 1 Bq/L. Measuring intervals varied from every hour to once a year, regularly or irregularly depending on the investigation. The main measuring items are air dose rate, gross ${\alpha}$, gross ${\beta}$, ${\gamma}$ radionuclide, Cs-134, Cs-137, Sr-89, Sr-90, I-131, and so on. In comparison, regulations about general public water in Korea need to be modified, while those about area near nuclear facility and drinking water are organized well. In future, therefore, domestic system would be expected to be modified with making reference to the guidelines like WHO's one. As good case of applying international guideline to domestic environment, Japanese system could be a reference when general standard of radioactivity in public water is made in Korea.

• Archives of design research
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• v.13 no.4
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• pp.33-41
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• 2000

More recently, the ecocide like an environmental shocks of acid rain, oil spills and now the ozone layer have driven home the fact that we're all responsible for looking after our natural environment and threaten the our right to live. At such a situation enterprises has been to develop techniques of enhancing environment friendly design. However it is difficult to producing environment friendly product - especially at electronic product like a high accumulated thing and produced with a small amount - while they know the importance of environment. Because of a direct and actual disadvantage of enterprise and customer. Moreover it is rare and negative for physical point that an adaptation case of recycled material or natural one for designing. Therefore it is important to positive consideration and action of design process for the nature. In this paper the focus of interest is find out the active and real environmental friendly design practice scheme as a designer and understanding of basic of the environmental friendly design for a coexistence of the enterprise, customer, and environment.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.2
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• pp.235-243
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• 2019

Radioactive materials are released into the air and deposited on the surface soil after a nuclear accident. Radionuclides deposited in soil are transported by precipitation to nearby environments and contaminate the surface water system. Basic data on surface watershed and soil erosion models have been collected and analyzed to evaluate the behavior of radionuclides deposited on surface soil after a nuclear accident. Data acquisition and analysis in aquatic environment were performed to investigate the physical characteristics and variation of biota in rivers and lakes of the Nakdong river area near the Wolsong nuclear power plant. For these purposes, a digital map, and hydrological, water quality and biota data were gathered and a systematic database (DB) was constructed in connection with them. Constructed aquatic DB will be supplied and used in surface watershed and soil erosion models for investigation of long-term movement of radionuclides in adsorptive form in surface soil. Finally, basic data and established models will be utilized for general radiological impact assessment in aquatic environment.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.115-119
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• 2005

As the regulations on DBPs are tightened, many water treatment plants (WTPs) in Korea have already introduced or will introduce enhanced coagulation, alternative disinfectants and advanced treatments such as ozonization and granular activated carbon to improve drinking water qualify. After a phenol leakage accident at the Nakdong-River in 1991, 26 WIPs in Korea introduced carbon dioxide generators, but there has been no accumulation of significant operating data. This research summarizes things that should be considered for the introduction of carbon dioxide disinfection process to WTPs based on one year operation data from A WTP that has had high concentration of DBP during a specific period in the summer. The removal efficiency of DBP was $30{\sim}40%$, but those of 2-MIB, Geosmin were less than 10%. The generation rate of $ClO_2$ by-products such as chlorite and chlorate were $70{\sim}100%$ of input dosage, but the ratios increased over time. At the same time, strong chlorine odors may be produced in the distribution system when $ClO_2$ was used with $Cl_2$ as a result of reaction between the chlorite and residual chlorine.

• Analytical Science and Technology
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• v.25 no.4
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• pp.236-241
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• 2012

There are many industrial factories in the central Nakdong river basin and have been occurred water pollution accidents by hazardous chemicals such as phenol, 1,4-dioxane and perchlorate. In this study, ten compounds of semi-volatile organic compounds (SVOCs) (dichlorvos, toluene-2,4-diisocyanate, 4,4'-methylenedianiline, 4,4'-methylenebis (2-chloroaniline), diethyl phthalate, di-n-butyl phthalate, butyl benzyl phthaltate, bis (2-ethylhexyl) adipate, benzophenone, 4,4'-bisphenol A) of hazardous chemicals which may be potentially discharged into the Nakdong river, were determined by gas chromatography-mass spectrometry (GC-MS) with disk-type solid-phase extraction. Accuracy and precision were in the range of 75.6~110.5%, and 4.6~12.7%, respectively and recovery was in the range of 72.4~127.9%. Three compounds (bis (2-ethylhexyl)adipate, benzophenone, 4,4'-bisphenol A) were detected in industrial wastewater such as wastewater treatment plants (WWTPs) and wastewater discharge facilities in the Nakdong River basin.

• Journal of Korean Society on Water Environment
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• v.34 no.4
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• pp.363-374
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• 2018

The Han River serves as an important water resource for the city of Seoul, Korea and in the neighboring metropolitan areas. From the Paldang dam to the Jamsil submerged weir, the 4 water intake stations that are located for the Seoul metropolitan population were under review in this study. Therefore the water quality management in this section is very important to monitor, analyze and review to rule out any safety concerns. In this study, a 3-D hydrodynamic model, EFDC (Environmental Fluid Dynamics Code), was applied to the downstream of the Paldang Dam in the Han River, which is about 23 km in length, to determine issues related to water resource management. The 3-D grid was composed of 2,168 horizontal grids and three vertical layers. In this case, the hydrodynamic model was calibrated and verified with an observed average daily water surface elevation, water temperature and flow rate data for 3 years (2013~2015). The developed EFDC model proved to reproduce the hydrodynamics of the Han River well. The composition ratios of the noted incoming flows at the monitored intake stations for 3 years and their flow patterns in the river were analyzed using the validated model. It was found that the flow of the Wangsuk Stream depended on the Paldnag dam discharge, and it was noted that the composition ratios of the stream at the intake stations changed accordingly. In a word, the Wangsuk Stream moved mainly along the right bank of the Han River under the condition of a normal dam flow. As can be seen, when the dam discharge rate was low, the incidence of lateral mixing was often seen. The scenario analyses were also conducted to predict the transport of conservative pollutants as in the case of a chemical spill accident. Generally speaking, when scenarios were applied, the arrival time and concentration of pollutants at each intake station was thus predicted.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.350-357
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• 2014

BACKGROUND: Deicers such as calcium chloride ($CaCl_2$) and sodium chloride (NaCl) in Korea have been commonly used to reduce traffic accidents as well as injuries. However there have been adverse effects of deciders such as pollution of water and soil, and reduced productivity of agriculture as well as forest. This study aimed to investigate biological effects of the deicers against wheat, barley, and spinach. METHODS AND RESULTS: The germination of tested crop seeds exposed to chloride-deicers, $CaCl_2$ and NaCl was significantly reduced at over 3% concentration of chloride-deicers compared to the control. In spraying deicers to the seedlings of the crops, there was no symptom such as inhibition of growth rate or leaf elongation. However the germination of tested crop seeds was affected at 2% concentration of deicers when they were exposed continuously to deicers in soils. The growth of the shoot against $CaCl_2$ and NaCl treatments was very similar in wheat and barley whereas the shoot of spinach was the most susceptible. Based on these results, the sensitivity of the crops to the tested deicers was as follows: NaCl > $CaCl_2$ > mixture ($CaCl_2$ + NaCl). The length of shoots and roots of the seedlings grown in 1% treated soil was decreased. The biomass of all the seedlings decreased 1.5 to 4 times at 1%. CONCLUSION: These results indicate that the effects of salt deicers by inputting into soil against growing tested crops are more severe in germination and growth inhibition as well as biomass decrease.

• Journal of Korean Society of Disaster and Security
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• v.12 no.1
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• pp.11-21
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• 2019

This study assessed the risk of disaster by using QRE(Quick Risk Estimation - UNISDR Roll Model City of Basic Evaluation Tool) tools for three natural disasters and sixteen social disasters managed by the Seoul Metropolitan Government. The criteria for selecting 19 disaster types in Seoul are limited to disasters that occur frequently in the past and cause a lot of damage to people and property if they occur. We also considered disasters that are likely to occur in the future. According to the results of the QRE tools for disaster type in Seoul, the most dangerous type of disaster among the Seoul city disasters was "suicide accident" and "deterioration of air quality". Suicide risk is high and it is not easy to take measures against the economic and psychological problems of suicide. This corresponds to the Risk ratings(Likelihood ranking score & Severity rating) "M6". In contrast, disaster types with low risk during the disaster managed by the city of Seoul were analyzed as flooding, water leakage, and water pollution accidents. In the case of floods, there is a high likelihood of disaster such as localized heavy rains and typhoons. However, the city of Seoul has established a comprehensive plan to reduce floods and water every five years. This aspect is considered to be appropriate for disaster prevention preparedness and relatively low disaster risk was analyzed. This corresponds to the disaster Risk ratings(Likelihood ranking score & Severity rating) "VL1". Finally, the QRE tool provides the city's leaders and disaster managers with a quick reference to the risk of a disaster so that decisions can be made faster. In addition, the risk assessment using the QRE tool has helped many aspects such as systematic evaluation of resilience against the city's safety risks, basic data on future investment plans, and disaster response.

• Korean Journal of Ecology and Environment
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• v.35 no.2 s.98
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• pp.63-70
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• 2002

Long-term changes of the fish fauna and its community structure from the Jungrang Creek of the Han River system in Seoul were investigeted from 1990 to 2000. Total species occurred during the survey period were 14 species in 6 families, and total individual number was 108,366. Fishes at the Jungrang Creek had not been distributed in the 1980s and 1990 because of heavy water pollution as well as environmental damage in the riparian areas. However, Cyprinus carpio and Carassius auratus in cyprinidae were rehabitated since the early 1990s when the water quality was improved because of foundation of sewage division pipe. Species nombers gradually increased to 6 species in 1996, 9 species in 1998, and 11 species in 2000. Individual numbers rapidly increased to 164 individuals in 1996, 146 individuals in 1998, and 108,094 individuals in 2000. A large number of Cyprinus carpio and Carassius auratus, which are abundantly distributed in the main course of the Han River, were found when they migrate to the upper reaches of the Jungrang Creek for spawning. Mass fish floatings were occurred on the 21st of April and the 11th of June in 2000 due to DO depletion at the lower site (Site 4) of discharging point of Jungrang sewage treatment plant and stagnant spot(Site 3) of dammed pool. Major dominant species were Cyprinus carpio and Carassius auratus (Cyprinidae). Others dominant species were Pseudorasbora lab대 (Cyprinidae) and Silurus asotus (Siluridae). Dominance indices were relatively high (0.79 to 1.00). Species diversity andrichness indices were relatively low (0 to 1.66and 0 to 1.41, respectively). Species diversity and richness indices were slightly higher at the middle reaches (Site 2 and Site 3) than the upper reaches and the mouth of the Jungrang Creek. However, the fish fauna of the Jungrang Creek was very poor and its community structure was very simple.