Ki S.J.,Gwangju Institute of Science and Technology |
Lee S.W.,Environmental and Plant Engineering Research Institute |
Kim J.H.,Gwangju Institute of Science and Technology
Desalination and Water Treatment | Year: 2015
Statistical models play an important role in elucidating the dynamic behaviors of surface water quality, given limited data on a large scale. In this study, we examine alternative approaches to develop regression models that predict fecal coliform (FC) concentrations in a river using different methods for selecting important variables provided by a self-organizing map (SOM). The raw data used as input to the SOM included 11 water quality, 6 meteorological, and 7 land use parameters that were monitored along the Yeongsan River in Korea on various time scales (from daily to half a decade) during 1996–2008. In both test and validation data sets, (multiple) regressions using backward elimination were compared against regression models via forced entry, which included a set of ranked variables simultaneously based on four indices in the SOM (i.e. structuring index, relative importance, cluster description, and Spearman’s rank correlation). Results showed that the SOM effectively illustrated the complex relationship between FC and the remaining variables in the entire data set. This relationship was seen more clearly in homogeneous clusters, indicating that the regression models became more robust in each subdivided group. While the original backward elimination model (R2 = 0.66) had much better performance than the models with four indices (R2 = 0.40–0.45) in the test data set, its performance (R2 = 0.42) was quite comparable to the relative importance model (R2 = 0.38) in the validation data set. Based on this preliminary study, we recommend further investigation of these indices for a reliable regression analysis, as the t values currently used for the variable selection in regressions provide only a locally optimal solution for the final model. The proposed methodology, if verified successfully, would be useful in developing early warning models that control mortality or disease rates of fishes in high-density aquafarms via water quality. © 2015 Balaban Desalination Publications. All rights reserved.
Shafique M.,Korean University of Science and Technology |
Kim R.,Korean University of Science and Technology |
Kim R.,Environmental and Plant Engineering Research Institute
Ecological Chemistry and Engineering S | Year: 2015
A low impact development (LID) is an alternative land development approach for managing stormwater that has been recommended instead of the traditional stormwater design. The main purpose of LID is to reduce the impact of development on water related problems through the use of stormwater management practices that infiltrate, evaporate, or harvest and use stormwater on the site where it falls. In recent years, more research has been carried out on the individual practice of LID such as bioretention, pervious pavements, rain garden and grassed swales. Nowadays LID practices have been successfully used to manage stormwater runoff, improve water quality, protect the environmental and hydrological aspects of the developed areas. Bioretention cells have been effectively used in retaining large volumes of runoff and pollutants on site. Pervious pavements have been extremely effective practice in infiltrating stormwater runoff as early as possible as rain fall on site and store a large quantity of water. Nowadays, sand ditch a new water harvesting technique is used that significantly reduces runoff and sediment losses and increases infiltration and soil loss. This paper highlights evidence in the literature regarding the beneficial uses of LID practices and encourage to adopt these practices for environmental friendly construction and sustainable development in the world. © 2015 Muhammad Shafique et al., published by De Gruyter Open 2015.
Kim R.,Environmental and Plant Engineering Research Institute |
Kim R.,Korean University of Science and Technology |
Lee J.-H.,Environmental and Plant Engineering Research Institute |
Lee D.,Korean University of Science and Technology
International Journal of Control and Automation | Year: 2015
This study has improved the infiltration capability of the sidewalk by infiltrating rainfall into the road and buffer green areas using the Permeable Brick Pavement (PBP) and Vertical Infiltration Pipe (VIP) and through the permeable retention tank under the PBP. Rainwater on impervious surfaces goes through the initial rainwater treatment system and then the rainwater storage tank; this process enables the slow rainfall-runoff for rainwater utilization. The rainwater collected in the rainwater storage tank is used for landscape irrigation in nearby green areas. Through this process, the runoff reduction rate on the road has been analyzed. The data used for the research were collected by measuring actual rainfall patterns: more than 30 mm of rainfall or more than 15 mm/hr of rainfall intensity in July and August 2014. As a result, the total outflow reduction efficiency of the Treatment-Train-package (T2P) System was about 60~70%. © 2015 SERSC.
Kim K.-S.,Environmental and Plant Engineering Research Institute |
Kim K.-S.,Korea Advanced Institute of Science and Technology |
Kim S.,Environmental and Plant Engineering Research Institute |
Jun T.H.,Korea Advanced Institute of Science and Technology
Water, Air, and Soil Pollution | Year: 2015
The dust removal performance of two types of modified electrode electrostatic precipitator systems was evaluated and compared with that of a conventional aluminum plate electrode using laboratory-scale experiments. In the novel electrode systems, the electrode surface was coated with activated carbon using a mixed slurry containing carbon black, polyvinyl acetate, and methanol. The modification of the electrode surface improved dust precipitation by increasing the specific capacitance of the electrode. The modification also lowered the electrode's resistance and increased its specific surface area. The optimum electrode spacing and electric voltage supply were determined using batch-type tests. In addition, dielectric insulators were applied as a partition between the oppositely charged electrodes equipped with the modified electrode plates. Multi-layered office paper cut to the same size as the electrodes was used as an insulating material. The addition of the insulator resulted in excellent improvement in the dust removal performance by minimizing the back-corona discharge phenomenon as well as doubling the dust collecting surface. Continuous dust removal tests with the three electrode systems revealed that whereas the conventional aluminum electrode exhibited 54 % dust removal, the activated carbon (AC)-coated system showed 85 % and AC-coated + insulator system showed 90 % and higher dust removal efficiency. © 2015 Springer International Publishing Switzerland.
Shin H.,Environmental and Plant Engineering Research Institute |
Han S.,Environmental and Plant Engineering Research Institute |
Hwang H.,Environmental and Plant Engineering Research Institute
Desalination and Water Treatment | Year: 2016
The operation and management of social infrastructures can create significant headaches for municipal governments. Sewer systems are no exception, and prioritizing plans and strategies for asset management is usually adopted as a cost-effective solution. The condition assessment, which is an important element of asset management, provides current information about the condition of municipal facilities. Condition assessments were first used by Water Research Centre (WRc) in the UK, the country with the longest history of sewer management, and are now widely used in many countries. Korea uses the condition assessment protocol developed by the Ministry of Environment (MOE), but as this protocol does not fully reflect the underground environment in Korea, the assessments and judgments are ambiguous. The sewer condition assessment and rehabilitation decision-making (SCARD) program developed by this study is based on the MOE protocol with the defect items, score, and condition grading system modified in consideration of the type of buried pipelines in Korea. To compare the assessment results produced by these two protocols, a closed-circuit television inspection was performed on 11 km of sewer pipeline in the sampled area in P city. The inspection indicated that SCARD set a higher score of structural defects common to both protocols for items that affect the collapse mechanism (fracture, damage, etc.). The amount of pipeline that received a grade of five for internal condition rating of identified structure defects was 45% with the MOE protocol, which was much higher than the 0.6% given with SCARD. This result showed that there was a big difference between the two protocols in condition grade evaluations of structural defects. In the future, the findings of this study can be used to develop an objective protocol reflecting actual sewer pipeline conditions. © 2016 Balaban Desalination Publications. All rights reserved.