• 농업과학연구
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• 제49권2호
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• pp.193-202
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• 2022

The recurrent neural network (RNN) algorithm has been widely used in water-related research areas, such as water level predictions and water quality predictions, due to its excellent time series learning capabilities. However, studies on water quality predictions using RNN algorithms are limited because of the scarcity of water quality data. Therefore, most previous studies related to water quality predictions were based on monthly predictions. In this study, the quality of the water in a reservoir in Nonsan, Chungcheongnam-do Republic of Korea was predicted using the RNN-LSTM algorithm. The study was conducted after constructing data that could then be, linearly interpolated as daily data. In this study, we attempt to predict the water quality on the 7th, 15th, 30th, 45th and 60th days instead of making daily predictions of water quality factors. For daily predictions, linear interpolated daily water quality data and daily weather data (rainfall, average temperature, and average wind speed) were used. The results of predicting water quality concentrations (chemical oxygen demand [COD], dissolved oxygen [DO], suspended solid [SS], total nitrogen [T-N], total phosphorus [TP]) through the LSTM algorithm indicated that the predictive value was high on the 7th and 15th days. In the 30th day predictions, the COD and DO items showed R² that exceeded 0.6 at all points, whereas the SS, T-N, and T-P items showed differences depending on the factor being assessed. In the 45th day predictions, it was found that the accuracy of all water quality predictions except for the DO item was sharply lowered.

• 한국관개배수논문집
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• 제17권2호
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• pp.95-104
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• 2010

Water quality data for 10 years (2000~2009) from about 826 reservoirs that are operated as a agricultural water quality survey network were analyzed in order to seek water quality management plan based on physical and chemical characteristics of agricultural reservoirs. The 95% reservoirs that exceed agricultural water quality standard of Chl-a (35mg/ $m^3$) had effective water depth shallower than 5m. The reason was that the reservoirs had more inflows of nutrient salts from the watershed, bigger surface water area of weak structure to algae occurrence. As the reservoirs of effective water depth shallower than 5m cover 49% of benefited area for irrigation, it is critical for agricultural water quality management of the reservoirs. The water quality of reservoir with shallower than 5m effective water depth was worse than reservoir with deeper than 5m effective water depth. Therefore, it is desirable that effective water depth of reservoirs make more than 5m for water quality management by building the bank higher and dredging the bottom of reservoirs.

• 한국환경과학회지
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• 제9권5호
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• pp.429-436
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• 2000

In order to study on the variational characteristics of water quality and chlorolphyll a concentration the water samples were collected daily or three times a week during the period from April 1990 to November 1991 at Kukdong port located in the northern Kamak bay of Southern Korea I made an analysis on biological factor as chlorophyll a concentration as well as physico-chemical factors such as water temperature salinity sigma-t dissolved oxygen, nutrients (ammonia, nitrite, nitrate, phosphate, and silicate) N/P ratio and chemical oxygen demand. In Northern Kamak bay seasonal variations in physical factors such as water temperature salinity and sigma-t were very marked. On the other hand chemical factors such as nutrients concentration and COD were not so. Chemical factors, in particular silicate were influenced by input of freshwater. And the roles of silicate on the seasonal succession of phytoplankton species composition was very low. Phytoplankton biomass as measured by chlorophyll a concentration was very high all the year round and it was controlled by the combination of several factors especially of N/P ratio determined by dissolved inorganic nitrogen.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.303-306
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• 2003

This survey was carried out to investigate the chemical characteristics of ground water for livestock purpose and to estimate the influence of ground water quality by livestock farming. Water samples were collected three times in 2000, and analyzed for theirs chemical compositions using Korean Standard Methods for Water Quality. The EC of ground water was from 0.214 to 0.474 dS/m. $NO_3-N$ contamination range was from 3.56 to 11.81. The $SO_4{^{2-}}$ was $4.31{\sim}69.37mg/L$ and CI was $12.75{\sim}41.46mg/L$. The data of ground water quality indicated suitable quality for livestock. Also, the concentration of heavy metals in the sample could not make damage to the animals. The $NO_3-N$ concentration of the water by times are as follows: October (8.19 mg/L) > July (7.65 mg/L) > April (4.04 mg/L) with no significant differences during the livestock farming period. The average quality of groundwater for livestock is good for its purpose, and it was showed there was few influence by livestock farming.

• 한국물환경학회지
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• 제28권1호
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• pp.26-37
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• 2012

Multi-dimensional hydrodynamic and water quality models are widely used to simulate the physical and biogeochemical processes in the surface water systems such as reservoirs and estuaries. Most of the models have adopted the Eulerian grid modeling framework, mainly because it can reasonably simulate physical dynamics and chemical species concentrations throughout the entire model domain. Determining the optimum grid cell size is important when using the Eulerian grid-based three-dimensional water quality models because the characteristics of species are assumed uniform in each of the grid cells and chemical species are represented by concentration (mass per volume). The objective of this study was to examine the effect of grid-size of a three dimensional hydrodynamic and water quality model (EFDC) on hydrodynamics and mass transport in the Saemangeum Reservoir. Three grid resolutions, respectively representing coarse (CG), medium (MG), and fine (FG) grid cell sizes, were used for a sensitivity analysis. The simulation results of numerical tracer showed that the grid resolution affects on the flow path, mass transport, and mixing zone of upstream inflow, and results in a bias of temporal and spatial distribution of the tracer. With the CG, in particular, the model overestimates diffusion in the mixing zone, and fails to identify the gradient of concentrations between the inflow and the ambient water.

• 환경위생공학
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• 제9권2호
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• pp.58-62
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• 1994

Until 1960 water pollution was caused by virus but now in according to industrial develop cent it has been continued environmental pollution by surfactant heavy metal, and hazardous chemical substance erst.. It is possible to Prevent contamination by virus owing to development of antibiotic but not to dissolve basely health effect by hazardous chemical substances because it takes very long time, about 5-40 years, average 20 years, in appearing a disease after exposure by then To maintain human life for 75 years, it need 55 ton of water. In the experiment of Public Health Institute, Tokyo, they reported that over 200 chemical substances can be detected in case of human being to drink tap water of Tokyo(1989) continuously. In our country, elevation of life style and development of industry result in increase of water use and overappreciation of pesticides in farm land a(sects drinking water quality. We estimated analytical item of drinking water hygienically by dividing into 5 groups such as physical effect item health hazardous inorganic item and health hazardous organic item ect. based on hygienic purpose.

• 분석과학
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• 제25권2호
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• pp.102-113
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• 2012

현행 환경오염공정시험기준 중 먹는 물 수질공정시험기준과 실내공기질 공정시험기준에 대해 국제규격에 부합화된 KS ISO규격과의 일원화에 관해 연구하였다. KS규격 23,000여종을 대상으로 먹는 물 및 실내공기질관련 KS 규격을 조사하였다. 환경분야관련 KS규격은 KS I로 분류되며, 총 653종으로 조사되었으며, 이중 국제규격에 부합화된 KS I 규격은 583종으로 조사되었다. 먹는 물 수질공정 시험기준은 총 100개 기준을 대상으로 ISO/TC 147 "Water Quality" 관련 KS 규격 총 232종을 비교 검토하였으며, 실내공기질 공정시험기준은 "ISO/TC 146 "Air Quality" 관련 KS 규격 총 95종 규격을 비교 검토하였다. 문헌검토와 비교시험을 통해 먹는 물 및 실내공기질 공정시험기준과 일원화 가능한 국제규격에 부합화된 KS규격 연구결과 먹는물수질공정시험 100개 기준 중 사전일원화 완료 23개 기준, 일원화 가능 29개 기준, 일원화 불가 12개 기준, 대응 규격 없는 기준이 36개로 평가되었으며, 실내공기질 공정시험기준 17개 기준 중 사전일원화 완료 1개 기준, 일원화 가능 3개 기준, 일원화 불가 3개 기준, 대응규격 없는 기준이 10개 기준으로 평가되었다.

• 한국환경보건학회지
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• 제42권4호
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• pp.280-292
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• 2016

Objectives: The objective of this study was to build COD regression models for the Han River and evaluate water quality. Methods: Water quality data sets for the dry season (as of January) during a four-year period (2012-2015) were collected from the database of the Han River automatic water quality monitoring stations. Statistical techniques, including combined genetic algorithm-multiple linear regression (GA-MLR) were used to build five-descriptor COD models. Multivariate statistical techniques such as principal component analysis (PCA) and cluster analysis (CA) are useful tools for extracting meaningful information. Results: The $r^2$ of the best COD models provided significant high values (> 0.8) between 2012 and 2015. Total organic carbon (TOC) was a surrogate indicator for COD (as COD/TOC) with high reliability ($r^2=0.63$ in 2012, $r^2=0.75$ for 2013, $r^2=0.79$ for 2014 and $r^2=0.85$ for 2015). The ratios of COD/TOC were calculated as 2.08 in 2012, 1.79 in 2013, 1.52 and 1.45 in 2015, indicating that biodegradability in the water body of the Han River was being sustained, thereby further improving water quality. The BOD/COD ratio supported these findings. The cluster analysis revealed higher annual levels of microorganisms and phosphorous at stations along the Hangang-Seoul and Hantangang areas. Nevertheless, the overall water quality over the last four years showed an observable trend toward continuous improvement. These findings also suggest that non-point pollution control strategies should consider the influence of upstreams and downstreams to protect water quality in the Han River. Conclusion: This data analysis procedure provided an efficient and comprehensive tool to interpret complex water quality data matrices. Results from a trend analysis provided much important information about sources and parameters for Han River water quality management.

• 수도
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• 제25권1호통권88호
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• pp.25-35
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• 1998

Factors controlling water quality, water-quality standards, and normal ranges of concentrations in unpolluted fresh water and the sources of elements were explained in this paper. In particular, the sources of groundwater contamination such as the disposal of domestic waste water, landfills, chemical spills and leaking underground tanks, and agricultural and mining activities were discussed.

• 한국물환경학회지
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• 제22권5호
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• pp.757-767
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• 2006

Biological assessments are the primary tool for evaluating the biological condition of a water body and makes it possible to understand accumulative and long-term effect of stressors. They also provide reliable biological information for which disturbed systems are to be restored. Sustainable water environment is not enough with attaining only the clean water, but it should sustain healthy and diverse aquatic life. Aquatic organisms are affected by various factors, including not only water quality but also habitat condition and stressors, and thus good condition of both physical and chemical water quality is prerequisite for sustaining healthy organisms. Therefore, biological assessment, along with other physical and chemical assessments, are crucial for evaluating the health of a water body. Overall, sustainability of water environment demands the attainment and maintenance of ecological integrity, which is resulted from the combination of physical, chemical and biological integrity. The biological criteria will play very important role in the water resource management and policy issues, and thus bioassessment program should be fully implemented and supported eventually by the law. To keep ecosystem health of water environment safely from the toxic pollutants and other stressors, the following suggestions need to be considered in environmental quality standards in Korea. For the first step, the biological indicators need to be introduced in evaluating river quality condition; they provide a qualitative description of biological condition of water body. Secondly, the biological water quality standards using biotic indices should be developed and implemented under the consideration of characteristics of Korean river systems. Lastly, the ecological status classification regime (ESCR) should be developed and introduced; it could be used in quality assessment of the water environment in general. In developing ESCR, integration of physico-chemical, biological, and habitat parameters should be taken into account.