• Journal of Korean Society on Water Environment
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• v.21 no.3
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• pp.236-241
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• 2005

The purpose of this study is to find out the source(s) and distribution of boron in Nak-dong River. In the year of 2002, the boron has been adopted as a toxic constituent for Korean drinking water standard. In this study, the analytical samples were collected at 11 stations in March, June, September and December 2002. These samples were analyzed by inductively coupled plasma-mass (ICP-MS) method. The recovery, relative standard deviation and method detection limit of the ICP-MS method for boron was $89{\sim}111.3%$, $2.21{\sim}3.81%$ and $5{\mu}g/L$, respectively. The distribution of boron was ranged $65{\sim}155{\mu}g/L$ in March, $26{\sim}125{\mu}g/L$ in June, $22{\sim}140{\mu}g/L$ in September and $50{\sim}162{\mu}g/L$ in December. The higher levels of boron were found at Kum-ho river nearby the industrial complex, which seemed to be greatly affected by domestic sewages and wastewater from the upper streams. Thus, the concentration of boron and that of other components showed strong statistical correlation in this area. In the Nak-dong River, industrial wastewater and domestic sewages is thought to be the sources of boron.

• Environmental Engineering Research
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• v.15 no.2
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• pp.105-109
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• 2010

The European Union (EU) Water Framework Directive (WFD) (2000/60/EC) was transposed into Irish law by Statutory Instrument Nos. 722 of 2003, 413 of 2005 and 218 of 2009, which set out a new strategy and process to protect and enhance Ireland's water resources and water-dependent ecosystems. The Directive requires a novel, holistic, integrated, and iterative process to address Ireland's natural waters based on a series of six-year planning cycles. Key success factors in implementing the Directive include an in-depth and balanced treatment of the ecological, economic, institutional and cultural aspects of river basin management planning. Introducing this visionary discipline for the management of sustainable water resources requires a solemn commitment to a new mindset and an overarching monitoring and management regime which hitherto has never been attempted in Ireland. The WFD must be implemented in conjunction with a myriad of complimentary directives and associated legislation, addressing such key related topics as flood/drought management, biodiversity protection, land use planning, and water/wastewater and diffuse pollution engineering and regulation. The critical steps identified for river basin management planning under the WFD include: 1) characterization and classification of water bodies (i.e., how healthy are Irish waters?), 2) definition of significant water pressures (e.g., agriculture, forestry, septic tanks), 3) enhancement of measures for designated protected areas, 4) establishment of objectives for all surface and ground waters, and 5) integrating these critical steps into a comprehensive and coherent river basin management plan and associated programme of measures. A parallel WFD implementation programme critically depends on an effective environmental management system (EMS) approach with a plan-do-check-act cycle applied to each of the evolving six-year plans. The proactive involvement of stakeholders and the general public is a key element of this EMS approach.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.5
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• pp.751-757
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• 2011

The monitoring technique based on electrical conductivity (EC) can provide researchers with some advantages in maintenance management and is cost-effective as compared with existing CSOs monitoring. In this study, the flow rate estimation using EC data was executed in two sites where storm overflow chamber had installed. In the result of A-site, R2 of second order multinomial between dilution ratio of EC and observed flow rate was showed the range of 0.68 ~ 0.77. And $R^{2}$ of B-site was 0.62 ~ 0.81. On the other hand, cumulative frequency of A-site was 43.4 ~ 52.2% in the relative error level of under 20%. And B-site was 10.1 ~ 46.5%. The flow rate estimation formula was improved through consideration of some parameters including antecedent dry days and rainfall duration. And difference between estimated flow rate and observed flow rate in total rainfall event was very small.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.4
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• pp.239-248
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• 2022

The prediction of algal bloom is an important field of study in algal bloom management, and chlorophyll-a concentration(Chl-a) is commonly used to represent the status of algal bloom. In, recent years advanced machine learning algorithms are increasingly used for the prediction of algal bloom. In this study, XGBoost(XGB), an ensemble machine learning algorithm, was used to develop a model to predict Chl-a in a reservoir. The daily observation of water quality data and climate data was used for the training and testing of the model. In the first step of the study, the input variables were clustered into two groups(low and high value groups) based on the observed value of water temperature(TEMP), total organic carbon concentration(TOC), total nitrogen concentration(TN) and total phosphorus concentration(TP). For each of the four water quality items, two XGB models were developed using only the data in each clustered group(Model 1). The results were compared to the prediction of an XGB model developed by using the entire data before clustering(Model 2). The model performance was evaluated using three indices including root mean squared error-observation standard deviation ratio(RSR). The model performance was improved using Model 1 for TEMP, TN, TP as the RSR of each model was 0.503, 0.477 and 0.493, respectively, while the RSR of Model 2 was 0.521. On the other hand, Model 2 shows better performance than Model 1 for TOC, where the RSR was 0.532. Explainable artificial intelligence(XAI) is an ongoing field of research in machine learning study. Shapley value analysis, a novel XAI algorithm, was also used for the quantitative interpretation of the XGB model performance developed in this study.

• Korean Journal of Environmental Agriculture
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• v.42 no.2
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• pp.83-92
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• 2023

Excess N and P from the livestock manure applied to farmlands, have entered the water systems and poses a serious threat to the natural environment. Consequently, there has been recent awareness towards the management of livestock manure and its related fields. In this study, piggery wastewater was collected from a piggery in Pohang city, Korea. At 800℃, thermal decomposition of a natural stone, magnesite (MgCO₃), yielded powered MgO with particle sizes ranging between 10 to 100 ㎛. Furthermore, NH₄⁺-N and PO₄^3--P were recovered as struvite precipitates from the piggery wastewater, by adjusting the pH with MgO and H₃PO₄. At pH 10, the recovery efficiencies of NH₄⁺-N and PO₄^3--P were found to be 86.1% and 94.1%, respectively. Using an X-ray Diffractometer (XRD), the struvite in the precipitate was confirmed to be consistent with standard pure struvite. Further, the purity of the struvite precipitate was analyzed using an energy dispersive X-ray (EDX) and thermal gravimetry-differential thermal analysis (TG-DTA), and found to be between 79.2% and 93.0%. Additionally, struvite-containing piggery wastewater and sawdust were mixed in a weight ratio of 2.5:1 and processed into a mature compost. The newly manufactured compost passed all quality standards required for first-class graded livestock composts. Moreover, this compost was sprayed directly onto the soil at the test site, and various parameters of the soil's effluent, such as total organic carbon (TOC), total nitrogen (T-N), total phosphorus (T-P), and dissolved oxygen (DO), were analyzed and measured. Based on these results, it is determined that the newly manufactured compost can more significantly reduce water pollution than commercial compost.

• Journal of Environmental Science International
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• v.20 no.6
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• pp.673-678
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• 2011

Water samples from several wastewater treatment plants and two industry drains in Gyeongsangbukdo were investigated for concentration levels of micropollutants. Samples were taken totally four times from May to November of 2008 and tested for seven factors including pesticide, 1,4-Dioxane and Perchlorate which had been big issues for Nakdong river because of their contaminations. As results, 2,4-D, Alachlor, and BEHA were not detected while BEHP was detected at some sampling sites. 1,4-Dioxane and Perchlorate were also detected in wide ranges from several sampling sites. Therefore, continuous supervising and monitoring systems needed to be invested for proper management for micropollutants since those micropollutants could affect human health and aquatic system with low concentration levels.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.3
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• pp.381-393
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• 2015

This study is carried out in order to propose a drought risk assessment methodology. This methodology is required to deal with practical questions that a variety of stakeholder often raise in the course of discussions on mitigation measures. With a focus on the socioeconomic aspect of drought, more particularly, residents' hardship from water scarcity, it suggests basic concepts and a system of methods in order to assess hazard, exposure, vulnerability and risk. The case study shows a considerable possibility of the methodology in evaluating potential levels of damages in a certain area, in identifying the boundary of districts where risk is disproportionately concentrated, and also in understanding the underlying risk factors of those districts. The authors think that the proposed methodology is able to offer risk information in terms of socioeconomic damages, and therefore contribute to reducing information gaps that policy-makers are currently encountered with.

• Journal of Wetlands Research
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• v.9 no.1
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• pp.69-78
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• 2007

Constructed wetlands and other aquatic systems have been successfully used for waste and wastewater treatment in either temperate or tropical regions. To treat waste or wastewater in a sustainable manner, the integrated eco-engineering designs are explained in this paper with 2 case studies: (i) a combination of vertical-flow constructed wetland (CW) with plant irrigation systemfor fecal sludge management and (ii) integrated CW units with landscaping at full-scale application for domestic wastewater treatment. The pilot-scale study of fecal sludge management employed 3 vertical-flow CW units, each with a dimension of $5{\times}5{\times}0.65m$ (width ${\times}$ length ${\times}$ media depth) and planted with cattails (Typha augustifolia). At the solid loading rate of 250 kg total solids (TS)/$m^2.yr$ and a 6-day percolate impoundment, the CW system could achieve chemical oxygen demand (COD), TS and total Kjeldahl nitrogen (TKN) removal efficiencies in the range of 80 - 96%. The accumulated sludge layers of about 80 - 90 cm was found at the CW bed surface after operating the CW units for 7 years, but no clogging problem has been observed. The CW percolate was applied to 16 irrigation Sunflower plant (Helianthus annuus) plots, each with a dimension of $4.5{\times}4.5m$ ($width{\times}length$). In the study, the CW percolate were fed to the treatment plots at the application rate of 7.5 mm/day but the percolate was mixed with tap water at different ratio of 20%, 80% and 100%. Based on a 1-year data of 3-crop plantation were experimented, the contents of Zn, Mn and Cu in soil of the experimental plots were found to increase with increasing in CW percolate ratios. The highest plant biomass yield and oil content of 1,000 kg/ha and 35%, respectively, were obtained from the plots fed with 20% or 50% of the CW percolate, whereas no accumulation of heavy metals in the plant tissues (i.e. leaves, stems and flowers) of the sunflower is found. In addition to the pilot-scale and field experiments, a case study of the integrated CW systems for wastewater treatment at Phi Phi Island (a Tsunami-hit area), Krabi province, Thailand is illustrated. The $5,200-m^2$ CW systems on Phi Phi Island are not only for treatment of $400m^3/day$ wastewater from hotels, households or other domestic activities, but also incorporating public consultation in the design processes, resulting in introducing the aesthetic landscaping as well as reusing of the treated effluent for irrigating green areas on the Island.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.3
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• pp.265-270
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• 2009

A nationwide questionnaire survey was conducted to investigate the actual conditions of local authorities in operating and maintaining sewerage systems especially for urban flooding. The questionnaire includes the incidences of flooding since 1980, the existence of any guidance for preventing flood damage and the design frequency currently used for sewers in each local authority. Among 160 local authorities responded to the survey, 95(59.3%) has experienced flooding more than once since 1980 while only 36(37.9%) of the 95 has prepared operation/maintenance guidelines for flooding. Most of the respondents have applied the 10 year design frequency for sewer design and 57(35.6%) of them agreed to adjust the 10 year design frequency regulation.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.479-486
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• 2012

Runoff characteristics of pollutant loads of the lower Han River was studied before full implementation of Total Pollution Load Management System(TPLMS). Magnitude of macroscopic(annual) fluctuation was in the order of Namhan River > Han River > Bukhan River, gross weight TP > gross weight TN > gross weight BOD, gross weight deviation > concentration deviation. Flux variation was higher than that of concentration. Microscopic(weekly) fluctuation showed similar pattern to macroscopic scale. TP showed the highest deviation resulting in the lowest reliability. 60% of annual flux passed during summer 3months resulting in 43-46% pass of gross weight at the lower Han River. Strong correlation was found between flux and gross weight especially in gross weight TN. Gross weight pollution increased as high as 400% while passing Seoul area due to the concentration. The deviation from moving average increased during summer season in the gross weight TP and BOD. Seasonal tendency was confirmed especially in gross weight TN and TP using autocorrelation function.