• Journal of Ocean Engineering and Technology
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• v.21 no.3 s.76
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• pp.8-15
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• 2007

This study is intended to examine the relationship between the magnitude of sand spit in the estuary of the stream and improvement of the quality of water that flaws into the sea, by means of hydraulic experimentation. In order to determine the effect of improvements of water quality when river flow is stagnant, the estuary flows into the sea through the small sand spit, and a two-dimensional physical model experiment was carried out. Distribution of concentration was decreased in response to an increase in length of sand spit and time. The experimental results are compared with theoretical results, based on the solution of the equation. Also, there are functions of influx prevention of salt wedge and purification of pollution water due to sand spit in small estuary.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.1
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• pp.212-225
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• 2015

In order to preserve the quality of fresh water in the artificial lake after the reclamation of an intertidal flat at the mouth of a river, we suggest two novel methods of water purification by using tidal potential energy and an enclosed permeable embankment called an utsuro (Akai et al., 1990) in the reclaimed region. One method uses an inflatable bag on the seabed within an utsuro, while the other uses a moored floating barge out of a dyke. Each case employs a subsea pipe to allow flow between the inside and outside of the utsuro. The change in water level in the utsuro, which is pushed through the pipe by the potential energy outside, caused circulation in the artificial lake. In this paper, we analyzed the inflatable bag and floating barge motion as well as the pipe flow characteristics and drafts as given by a harmonic sea level, and compared the theoretical value with an experimental value with a simple small model basin. The numerical calculation based on theory showed good agreement with experimental values.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.5
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• pp.421-430
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• 2017

In this study, a model was developed to predict for Disinfection By-Products (DBPs) generated in water supply networks and consumer premises, before and after the introduction of advanced water purification facilities. Based on two-way ANOVA, which was carried out to statistically verify the water quality difference in the water supply network according to introduce the advanced water treatment process. The water quality before and after advanced water purification was shown to have a statistically significant difference. A multiple regression model was developed to predict the concentration of DBPs in consumer premises before and after the introduction of advanced water purification facilities. The prediction model developed for the concentration of DBPs accurately simulated the actual measurements, as its coefficients of correlation with the actual measurements were all 0.88 or higher. In addition, the prediction for the period not used in the model development to verify the developed model also showed coefficients of correlation with the actual measurements of 0.96 or higher. As the prediction model developed in this study has an advantage in that the variables that compose the model are relatively simple when compared with those of models developed in previous studies, it is considered highly usable for further study and field application. The methodology proposed in this study and the study findings can be used to meet the level of consumer requirement related to DBPs and to analyze and set the service level when establishing a master plan for development of water supply, and a water supply facility asset management plan.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.1
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• pp.41-50
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• 2003

The feasibility as floricultural crops and water garden plant materials of Korean native water plants was investigated. Propagation type, growing and flowering time were observed for development as water garden, interior aquarium plant and water purification materials. Flowering time of the water plant was 7 species in May, 28 species in June, 49 species in July, 55 species in August, 47 species in September, and 17 species in October. Beautiful flowering water plants were Nymphaeaceae, Nymphoides peltata, Nymphoides indica, Monochoria korsakowii, Iris pseudacorus, Iris laevigata, and etc. Ornamental leafy water plants were Ceratopteris thalictroides, Ludwigia ovalis, Myriophyllum verticillatim, Limnophila sessiliflora, Blyxa aubertii, Blyxa echinosperma, Vallisneria asiatica, Hydrilla verticillata and Eleocharis acicularis etc. Isoetes japonica, Isoetes coreana and Isoetes sinensis were propagated by spore. Blyxa aubertii, Blyxa echinosperma, Myriophyllum verticillatim, Nuphar japonicum, Nelumbo nucifera, Ottelia alismoides, Sagittaria aginashi, Trapa japonica, and Trapa natans were propagated by seed. Persicaria amphibia, Ceratophyllum demersum (hornwort), Myriophyllum verticillatim, Myriophyllum spicatum, Oenanthe javanica, Potamogeton crispus, Hydrilla verticillata and Acorus calamus were propagated by division. And Vallisneria asiatica, Hydrilla verticillata and Phragmites japonica were propagated by runner. Ceratophyllum demersum (hornwort), Myriophyllum verticillatim, Myriophyllum spicatum, Limnophila sessilifera were propagated by adventitious bud. Ceratopteris thalictroides was propagated by leaf cutting. The 35 genera, 68 species of water plants were available for horticultural use. The 45 species such as Iris laevigata, Eleocharis acicularis, Menyanthes trifoliata, Nymphaea minima, Nuphar pumilum, Nymphoides coreana, Nymphoides peltata, Nymphoides indica, Nymphaea tetragona (water lily), and Typha latifolia could be use for water garden plant. The 21 species such as Limnophila sessilifera, Vallisneria asiatica, Ceratophyllum demersum and Hydrilla verticillata available for indoor aquarium. The 19 species such as Ottelia alismoides, Oenanthe javanica, Limnophila sessilifera and Blyxa echinosperma could be culture in container. The 27 species such as Trapa japonica, Trapa incisa, Phramites commuris (reed), Phragmites japonica, and Zizania latifolia were usable for water purification plant materials.

• Journal of Ocean Engineering and Technology
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• v.31 no.3
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• pp.248-255
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• 2017

Many rivers and seas have been affected by environmental contamination. Therefore, city water supplies often require a high-degree purification treatment to provide safe drinking water. However, in order to achieve a high-degree purification treatment, a large amount of chlorine has to be added to sterilize city drinking water. The added chlorine reacts chemically with water and forms hypochlorous and chlorine ions. The hypochlorous ionizes with hypochlorous ions and hydrogen ions. As a result, the city water contains a large amount of chlorine ion. As such, when city water is used with domestic boilers, many kinds of heat exchangers, and the engines of vehicle and ships, there are often corrosion problems. In this study, alkali water was electrochemically made by electrolysis of city water, and corrosion properties between alkali and city water were investigated with an electrochemical method. Most of the chlorine ions are thought to not be contained in the alkali water because the alkali water is created in the cathodic chamber with an electrolysis process. In other words, the chlorine ion can be mostly removed by its migration from a cathodic chamber to an anodic chamber. Moreover, the alkali water also contains a large amount of hydroxide ion. The alkali water indicated relatively good corrosion resistance compared to the city water and the city water exhibited a local corrosion pattern due to the chlorine ion created by a high-degree purification treatment. In contrast, the alkali water showed a general corrosion pattern. Consequently, alkali water can be used with cooling water to inhibit local corrosion by chlorine ions in domestic boilers, various heat exchangers and the engine of ships and for structural steel in a marine structure.

• Journal of Korean Society on Water Environment
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• v.40 no.2
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• pp.89-100
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• 2024

Climate change has a broad impact on the entire water environment, and this impact is growing. Climate adaptation in water supply systems often involves quantity and quality control, but there has been a lack of research examining the impacts of climatic factors on water supply productivity and operation conditions. Therefore, the present study focused on, first, building a database of climatic factors and water purification operating conditions, and then identifying the correlations between factors to reveal their impacts. News big data was analyzed with keywords of climatic factors and water supply systems in either nationwide or region-wide analyses. Metropolitan area exhibited more issues with cold waves whereas there were more issues with drought in the Southern Chungcheong area. A survey was conducted to seek experts' opinions on the climatic impacts leading to these effects. Pre-chlorination due to drought, high-turbidity of intake water due to rainfall, an increase of toxins in intake water due to heat waves, and low water temperature due to cold waves were expected. Pearson correlation analysis was conducted based on meteorological data and the operating data of a water purification plant. Heavy rain resulted in 13 days of high turbidity, and the subsequent low turbidity conditions required 3 days of high coagulant dosage. This insight is expected to help inform the design of operation manuals for waterworks in response to climate change.

• Parasites, Hosts and Diseases
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• v.53 no.6
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• pp.745-747
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• 2015

Cryptosporidium, a protozoan parasite that causes watery diarrhea, is found worldwide and is common in areas with low water hygiene. In February 2014, 866 stool samples were collected from the inhabitants of 2 rural areas in White Nile State, Sudan. These stool samples were assessed by performing modified acid-fast staining, followed by examination under a light microscope. The overall positive rate of Cryptosporidium oocysts was 13.3%. Cryptosporidium oocysts were detected in 8.6% stool samples obtained from inhabitants living in the area having water purification systems and in 14.6% stool samples obtained from inhabitants living in the area not having water purification systems. No significant difference was observed in the prevalence of Cryptosporidium infection between men and women (14.7% and 14.1%, respectively). The positive rate of oocysts by age was the highest among inhabitants in their 60s (40.0%). These findings suggest that the use of water purification systems is important for preventing Cryptosporidium infection among inhabitants of these rural areas in Sudan.

• Journal of Wetlands Research
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• v.9 no.2
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• pp.71-84
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• 2007

Masan Bay is a representative semi-closed bay acted as a sedimentation reservoir with a slow current velocity and a poor water circulation in Korea. The pollutants from terrestrial sources into the Masan Bay have apparently environmental pollution problems, such as eutrophication, red tied, and hypoxia. In this study, An ecological modeling work was performed to estimate the material circulation including the growth of bivalve in ecosystem. Furthermore, the effect of water purification was calculated by filter feeding bivalve to particulate organic matter just like COD and phytoplankton. And Water quality management strategy by bio-purification of bivalve is derived through selection of location, quantification of bivalve aquaculture farm. The results showed that the optimum location for bivalve farming is where phytoplankton accumulation by physical processes is maximized and the optimum density and area of bivalve are 35 individuals $m^{-3}$ and ca. 500 hectare, respectively. When assuming conditions for the optimum growth of bivalve, COD could decrease by up to 18% even without other reduction of pollution loads.

• KCID journal
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• v.11 no.1
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• pp.36-44
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• 2004

The objective of this study is to analyze the characteristics of the nutrients loading and the water purification function in the paddy-fields. This study was carried out based on the research data in the three case studies. 1. Irrigation requirement is m

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.127-127
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• 2017