• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.47-50
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• 1999

From 1997 irrigation water withdraws has been surveyed for the purpose of river operation and management . Recently , the River Law was revised (1999.2.8) and obligate to water users to report their proposed and actual water withdrawals. If we can save more water from rice paddy area, we can use more water for municipal and industrial activity and we can expect water quality should be improved in the river. So the role of irrigation water use efficiency is more and more important.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.6
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• pp.794-800
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• 2004

The purpose of this study is to propose a method of controlling freshwater algae which grows abundantly and forms water bloom in the eutrophic water body with $H_2O_2$. Both laboratory and field methodologies were used. For the laboratory test $H_2O_2$ was injected into the different growth phases of incubated Microcystis aeruginosa and the resulting algae growth control rate was examined. For the field test, $H_2O_2$ was dispersed into a lake. Lake water quality was evaluated using a pre-test and post-test analysis of chlorophyll-a, luminance, transmittance, etc., which allowed a comparative evaluation of water quality change. From the experimental results, the growth of algae can be controlled with the small amount of 1mg/L of $H_2O_2$ at the lag phase of growth. The field test results show that the green colour of lake water was removed completely by the reduction of chlorophyll-a and improved transmittance, luminance, TKN, TP, TOC and SS. These indicators of water quality were improved significantly after $H_2O_2$ injection. Toxicity test results using the lake fish show no evidence of detrimental effect of $H_2O_2$ up to 15mg/L. The results of $EC_{50}$ with P. phosphoreum show that the toxicity of $H_2O_2$ was negligible compared to copper which was commonly used for algae control.

• Clean Technology
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• v.27 no.3
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• pp.217-222
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• 2021

Although monolayer black phosphorus (BP) and few-layer BP nanosheets (NSs) have been extensively studied as promising alternatives to graphene, research has focused primarily on atomically thin-layered BP in an isolated form. In order to realize the practical applications of BP-related devices, a BP film based on continuous networking of few-layer BP NSs should be developed. In this study, a transparent BP film with high quality was fabricated via a vacuum filtration method. An oxygen-free water solvent was used as an exfoliation medium to avoid significant oxidation of the few-layer BP NSs in liquid-phase exfoliation. The exfoliation efficiency from bulk BP to the few-layer BP NSs was estimated at 22%, which is highly efficient for the production of continuous BP film. The characteristics of the high-quality BP film were determined as 98% transparency, minimum oxidation of 18%, structural stability, and an appropriate bandgap of about 1.8 eV as a semiconductor layer. In order to demonstrate the potential of the BP film for photocatalytic activity, we performed photoelectrochemical water oxidation of the transparent BP film. Although its performance should be improved for practical applications, the BP film could function as a photoanode, which offers a new potential semiconductor in water oxidation. We believe that if the BP film is adequately engineered with other catalysts the photocatalytic activity of the BP film will be improved.

• Journal of Environmental Health Sciences
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• v.43 no.2
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• pp.143-156
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• 2017

The purpose of this study was to investigate water quality through a field survey at six floor fountain sites. The floor fountain facilities were designed and operated in such a way that tap water was stored in a water tank and recycled repeatedly. The water tank was cleaned once or twice per week in the summer. The number of facility users was low during the day due to sweltering heat, but up to 40 people, mainly children, were using them around 8 pm. Since the operation time was as short as 30 minutes, it is considered necessary to extend it for at least one hour for the number of users. As a result of the water quality test of the reservoir tank prior to operation after cleaning, it was measured to be within drinking water quality standards at the six facilities. As a result of the water quality test after use, ammonia nitrogen was measured to be 1.45 mg/L at Site IV. This exceeded the drinking water quality standard of 0.5 mg/L. In the case of turbidity, two cases exceed at 7.38 and 4.52 NTU when applying 4 NTU as the water quality standard for waterscape facilities. Twenty-eight cases exceed the standard of drinking water quality. The result of microbiological tests, at five sites excepting Site I, where disinfectant was injected, was that the maximum total colony count was 180,000 CFU/mL, total coliforms was 2,100,000 CFU/100 mL, fecal coliforms was 4,600 CFU/100 mL, Escherichia coli was 170 MPN/100 mL and Enterococcus was 100 CFU/100 mL. This exceeded the water quality standards of drinking water. Children are very likely to inhale because the water spews from below and falls from above, so it is necessary to apply water quality standards for ammonia nitrogen, turbidity and microbes. Current floor fountain facilities are highly susceptible to disease caused by microbial contamination because of water cycling and reuse, so it is necessary to change the water every day, clean the water tank, and perform chlorination. Therefore, it is necessary to inject calcium hypochlorite according to the free chlorine water quality standard of swimming pools with a different water tank capacity. In addition, facilities should be improved to prevent the reuse of water by installing the water tank at a separate location.

• Spatial Information Research
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• v.12 no.1
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• pp.13-27
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• 2004

The current industrial development and the increase of population in Daecheong Reservoir basin have produced a rapid increase of wastewater discharge. This has resulted in problem of water quality control and management. Although many efforts have been carried out, reservoir water quality has not significantly improved. In this sense, the development of water quality management system is required to improve reservoir water quality. The goal of this study is to design a GIS-based water quality management system for the scientific water quality control and management in the Daecheong Reservoir. For general water quality analysis, WASP5 model was applied to the Daecheong Reservoir. A sensitivity analysis was made to determine significant parameters and an optimization was made to estimate optimal values. The calibration and verification were performed by using observed water quality data for Daecheong Reservoir. A water quality management system for Daecheong Reservoir was made by connecting the WASP5 model to ArcView. It allows a Windows-based Graphic User Interface(GUI) to implement all operation with regard to water quality analysis. The proposed water quality management system has capability for the on-line data process including water quality simulation, and has a post processor far the reasonable visualization for various output. The modeling system in this study will be an efficient NGIS(National Geographic Information System) far planning of reservoir water quality management.

• Food Science and Preservation
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• v.10 no.1
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• pp.32-36
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• 2003

Quality stability of the dried layer Porphyra tenera depending on various light sources, water activities, packaging materials and storage temperatures were investigated by peroxide value and chlorophyll degradation. Major fatty acids of dried layer were 45.7％ eicosapentaenoic acid and 13.6% palmitic acid. Quality stability was increased in order of darkness, incandescent and fluorescent increased sharply with the decrease of water activity and temperature, and also improved by the packaging material with strong barriers of water vapor, oxygen and light.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.863-871
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• 2007

Spectroscopic characteristics of river water from four major watersheds in the Ulsan area were measured to examine their potential for estimating water quality parameters. The total 176 river samples were collected from 44 sites of small streams within the watersheds during the year 2006. Spectroscopic characteristics investigated included protein-like fluorescence (FLF) intensity, fulvic-like fluorescence (FLF) intensity, terrestrial humic-like fluorescence (TLF) intensity, UV absorbance at 254 nm, and UV absorbance difference at 220 nm and 254 nm. Protein-like fluorescence intensity showed linear relationships with biochemical oxygen demand (BOD), chemical oxygen demand (COD), total phosphorous (TP) concentrations of the samples with the correlation of 0.784, 0.779, and 0.733, respectively. Due to the UV absorption characteristics of nitrate at 220 nm, UV absorbance difference at 220 nm and 254 nm was selected to represent total nitrogen (TN) concentration. Exclusion of some samples with PLF intensity higher than 5.0 improved the correlation between the UV absorbance difference and TN as demonstrated by the increase of the correlation coefficient from 0.392 to 0.784. Instead, for the samples with PLF intensity lower than 5.0, the highest correlation of TN was achieved with UV absorbance at 254 nm. The results suggest that PLF intensity could be used as the estimation index for BOD, COD, and TP concentration of river water, and as the primary screening index for the prediction of TN using UV absorbance difference. Some BOD-based water quality levels among the river water were statistically discriminated by the PLF intensity. Low p-values were obtained from the t-tests on the samples with the first level and the second level (p=0.0003) and the samples with the second and the third levels (p=0.0413). Our combined results demonstrated that the selected spectroscopic characteristics of river water could be utilized as a tool for on-site real-time monitoring and/or the primary estimation of water quality.

• Journal of Korean Society on Water Environment
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• v.37 no.4
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• pp.263-274
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• 2021

This study presents the achievements and limitations of the voluntary-based Total Maximum Daily Load (TMDL) through statistical analysis of water quality monitoring data and performance assessments of TMDL plans implemented in the Gyeongan watershed. The results clearly showed that responsible local governments complied the allocated TMDL and the designated water quality goals were successfully achieved in the required period. This was possible because the Ministry of Environment provided innovative incentives, such as, relaxations of the existing tight land-use regulations and full-scale financial aids for constructing and operating public treatment facilities to draw local government voluntary participation. However, a couple of problems which decreased the effectiveness and efficiency of the voluntary TMDL were identified. The different TMDL implementation schedules between upstream (Yongin) and downstream (Gwangju) governments caused delay in water quality improvement and exaggerated TMDL allocation to the local development which made excessive investment in the treatment facilities. Although it is not directly related to the voluntary scheme, technical methods for establishing and assessing the water quality goals should be improved so that the effects of flow conditions on water quality are properly assessed. We expect that results of this case study contribute to developing a more effective voluntary-based scheme for the implementation of the so-called 'tributary TMDL' in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5B
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• pp.419-427
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• 2009

In existing studies about benefit of water quality improvement using WTP, the object of survey is described pre-policy water quality as "current water quality" and improved (post-policy) water quality as "boatable, fishable and swimmable". Multiply WTP by the number of households of basin is total benefit. The existing studies are not benefit of a specific water resource business but benefit of a policy on unsubstantial water resource business. Because of a lack of objectivity and oversimplification, it is difficult for survey respondents to understand an object of survey. The purpose of this study is to evaluate a benefit estimation methodology for raw water quality improvement in water resource development business. After conducting a survey of WTP of 1,000 housewives who is using water service in the National Capital region, the relational expression of water quality improvement (BOD) and WTP is derived by using statistical analysis of the survey. As a case study, the stream water quality improvement benefit of Song Li Won multipurpose dam was evaluated, which is planned to be built at the local secondary stream section on Nae Sung stream in Nak-Dong River system. As a result of study, annual average benefit evaluation is 5,980 million won on the average annual planned discharge, 8,663 million won on the planned discharge during the period except for wet season (July to October), 11,905 million won on the planned discharge during water quality declining period and 14,502 million won on the planned discharge during water quality declining period respectively. By using the relational expression of BOD-WTP, it is easy to estimate the benefit without regard for water quality.

• Environmental Engineering Research
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• v.13 no.4
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• pp.197-202
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• 2008

This study evaluated the photocatalytic oxidation of BPA using the RPOD reactor under various conditions. This study found that the RPOD was effective for BPA degradation. It could reduce 1 mg/L of BPA by half within 5 min under the optimum conditions. According to the study results, $TiO_2$ coating was important for the BPA oxidation. As the coating thickness increased, the removal efficiency improved. The light source, the light intensity and the drum rotating speed were important for the oxidation. The UV light was more effective for the BPA degradation than the visible light. The removal efficiency improved with increasing intensity. As the drum speed increased, the removal efficiency improved. The maximum speed was 240 rpm in this study. Addition of air and nitrogen was not beneficial for the BPA degradation in this study probably due to enough oxygen in the water.