• Journal of Microbiology and Biotechnology
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• v.21 no.2
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• pp.115-123
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• 2011

To investigate the effects of pipe materials on biofilm accumulation and water quality, an annular reactor with the sample coupons of four pipe materials (steel, copper, stainless steel, and polyvinyl chloride) was operated under hydraulic conditions similar to a real plumbing system for 15 months. The bacterial concentrations were substantially increased in the steel and copper reactors with progression of corrosion, whereas those in stainless steel (STS) and polyvinyl chloride (PVC) reactors were affected mainly by water temperature. The heterotrophic plate count (HPC) of biofilms was about 100 times higher on steel pipe than other pipes throughout the experiment, with the STS pipe showing the lowest bacterial number at the end of the operation. Analysis of the 16S rDNA sequences of 176 cultivated isolates revealed that 66.5% was Proteobacteria and the others included unclassified bacteria, Actinobacteria, and Bacilli. Regardless of the pipe materials, Sphingomonas was the predominant species in all biofilms. PCR-DGGE analysis showed that steel pipe exhibited the highest bacterial diversity among the metallic pipes, and the DGGE profile of biofilm on PVC showed three additional bands not detected from the profiles of the metallic materials. Environmental scanning electron microscopy showed that corrosion level and biofilm accumulation were the least in the STS coupon. These results suggest that the STS pipe is the best material for plumbing systems in terms of the microbiological aspects of water quality.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.8 no.1
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• pp.11-14
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• 2002

Packaging and distribution status of watermelon Korean markets; Chunanm and Chunbuk, Kyungnam and Kyungbuk from January, 1999 to December, 1999 was surveyed to shipping methods, quality. Distribution and marketing of watermelon was different to the producing area, and quality of it was four grade. In a grade, difference of weight was 86%, and that of soluble solid content was 130%. Packaging status was almost non-pack, in case of packaging, packaging material was corrugated fiberboard and wooden-collar box, and packaging unit was mainly used to 8 to 10kg box, for one head or 4 heads was a few.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.260-266
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• 2009

Non-revenue water reduction(NRW) technologies are implemented to evaluate and manage leakages scientifically in water distribution systems under local governments. A development of quantitative leakage indicator by measuring minimum night flow, pressure control policy by installation of PRV(pressure reducing valve) and the establishment of leakage prevention schemes by residual life modeling of deteriorated water pipes are reviewed and studied. Estimation models of allowable leakage are developed by measuring and analyzing minimum night flow at residential and commercial area in Nonsan city, which is suggested from UK water industry and can improve an existing leakage indicator for the evaluation of non-revenue water. Also, pressure control method is applied and analyzed to Uti distribution area in Sacheon city in the operation aspect. As results, $466\;m^3/day$ of leakage can be reduced and it is expected that 113million won of annual cost can be saved. In the part of corrosion velocity and residual life assessment, non-linear prediction models of residual thickness are proposed by assessment of corrosion velocity based on exposure years, soil and water quality etc., since the deteriorated water pipe play a major role to increase leakage. It is expected that collection data and analyzing results can be applied effectively and positively to reduce non-revenue water by accumulating surveying data and verifying the results in the business field of water distribution systems under local governments.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.4
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• pp.267-276
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• 2020

In this study, air scouring cleaning was selected and applied among 5 small blocks (S1~S5) in domestic S cities to analyze the cleaning effect of particles causing discoloration. In order to identify the cleaning effect, 10 locations were selected as water quality investigation point, such as the stagnant or water mains ends. Removal of solids, variation of particle components, weight and concentration were analyzed. And the level of the cleanness of the surface inside water mains using endoscope was investigated. As a result of analysis, the solids discharged after cleaning were mainly sand and gravel, pieces related to pipe materials, and corrosion products. As a result of analyzing the concentrated particles of the filter before and after cleaning, it was found that the change in discoloration on the filter was large. In addition, as a result of comparing the weight and the concentration of the particles, it was found that the particles causing discoloration were significantly removed after cleaning. From the results of the endoscopy, it was confirmed that most of the precipitated and accumulated dark yellow discoloration matters inside water mains were removed through cleaning. Therefore, it seems that the particles causing discoloration in water decreased after cleaning. Therefore, it is expected that, if properly cleaning was applied, matters that cause discoloration can be removed from the water mains, and customer's complaints can also be reduced through water quality improvement.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1323-1336
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• 2010

This study was carried out to determine marine environments and phytoplankton community around Mokpo harbour on March to November during the period of 2004-2009. The remarkable fluctuations of marine environments were shown around Mokpo harbour depending on monthly and yearly. Among seasons, summer was a great that was associated with extremely releasing the freshwater from Youngsan River Weir, contributing to effect the fluctuations of water quality. Nevertheless of monthly and yearly, the molecular ratio of N:P was always shown in above 16 that was mainly attributed to freshwater discharge on March to November. This indicates that phosphorus playes an important role in limiting factor as growth in phytoplankton. During this study, Skeletonema costatum was found to be richer than the other groups of diatoms in terms of abundance and species number. Mokpo harbour, with the presence of a narrow avenue for exchange with offshore waters, has limited growth in phytoplankton, but this species is able to well adapt and fast grow under even high level of suspended solid and low intensity of light compared with other species. The discharge of freshwater is associated with significantly fluctuation of marine environments in this region, but it does not affect the quantitative and qualitative distribution of phytoplankton. It is necessary to persistently monitor based on water quality and phytoplankton community.

• Environmental Engineering Research
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• v.21 no.2
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• pp.171-179
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• 2016

This study analyzes guidelines to select optimum number of grids to represent behavior of a given water system appropriately. The EFDC model was chosen as a 3-D hydrodynamic and water quality model and salt was chosen as a surrogate variable of pollutant. The model is applied to an artificial canal that receives salt water from coastal area and fresh water from a river from respective gate according to previously developed gate operation rule. Grids are subdivided in vertical and horizontal (longitudinal) directions, respectively until no significant changes are found in salinity concentrations. The optimum grid size was determined by comparing errors in average salt concentrations between a test grid systems against the most complicated grid system. MSE (mean squared error) and MAE (mean absolute error) are used to compare errors. The CFL (Courant-Friedrichs-Lewy) number was used to determine the optimum number of grid systems for the study site though it can be used when explicit numerical method is applied only. This study suggests errors seem acceptable when both MSE and MAE are less than unity approximately.

• Journal of Soil and Groundwater Environment
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• v.24 no.1
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• pp.17-23
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• 2019

Clean soil environment is of crucial importance to sustain lives of ecosystem and humans. With rapid industrialization, there has been a great increase of soil contamination by accidental releases of petroleum products. In general, soil remediation is an expensive and time-consuming process as compared to cleanup of water and air. Moreover, determining the source and responsible parties of soil pollution often turns into legal conflicts and that further delay the cleanup process of contaminated sites. In practice, total petroleum hydrocarbon (TPH) analysis has been employed to determine the petroleum species and to track down the responsible polluters. However, this approach often suffers from differentiating similar TPH species. In this study, we analyzed TPH chromatogram patterns of 24 domestic petroleum products in specific carbon ranges (${\sim}C_{10}$, $C_{10}-C_{12}$, $C_{12}-C_{36}$, and $C_{36}{\sim}$) and the fractional changes of THP ratio in the mixture products of gasoline, kerosene and diesel. The proposed TPH analysis method in this study could serve as a useful tool to better analyze the petroleum species in soils contaminated with complex oil mixtures, and ultimately be used to identify the polluters of soil.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.3
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• pp.203-218
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• 2011

Long-term trends and distribution patterns of water quality were investigated in the Yeoja Bay of South Sea, Korea from 1976 to 2010. Water samples were collected at 3 stations and physicochemical parameters were analyzed including water temperature, salinity, hydrogen ion concentration (pH), dissolved oxygen (DO), chemical oxygen demand (COD), suspended solids (SS) and nutrients. Spatial distribution patterns of temperature, pH and DO were not clear among stations but the seasonal variations were distinct except ammonium. The trend analysis by principal component analysis (PCA) during 31 years revealed the significant variations in water quality in the study area. Spatial water qualities were discriminated into 2 clusters by PCA; station cluster 1 and 2~3. Annual water qualities were clearly discriminated into 4 clusters by PCA. By this multi-variate analysis, the annual trends were summarized as the followings; water temperature, COD and SS tended to increase from late 1970's, decreased salinity, and increased phosphate from 1991 to 2001 and increased dissolved inorganic nitrogen. Water quality was showed by the input of fresh water same as those of Kyoungin coastal area, Asan coastal area, Choensoo bay, Gunsan coastal and Mokpo coastal area in the Yeoja Bay.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.1
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• pp.11-20
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• 2018

This study is to calibrate the SWAT (Soil and Water Assessment Tool) water quality of SS (Suspended Solid), T-P (Total Phosphorus), and T-N (Total Nitrogen) by focusing on 2014~2015 drought periods and identify the important parameters. For Gongdo watershed ($366.5km^2$), the SWAT was calibrated for 2 cases of 2002~2006 normal year focusing calibration and 2014~2015 drought focusing calibration respectively. The parameters of N_UPDIS (Nitrogen uptake distribution parameter) and CMN (Rate factor for humus mineralization of active organic nutrients) played important roles for T-N calibration during drought periods. The SWAT SS, T-N, and T-P average $R^2$ (Coefficient of determination) results by focusing on 2014~2015 drought periods calibration showed 0.71, 0.65 and 0.62 while 2002~2006 normal year focusing calibration showed 0.63, 0.58 and 0.50 respectively. Also SWAT SS, T-N, and T-P model efficiency NSE (Nash-Sutcliffe efficiency) results by focusing on drought period (2014~2015) calibrated showed 0.76, 0.77, 0.87 respectively. Even though the SS, T-P parameters were unchanged during the calibration, the SS and T-P results were improved by the hydrological parameters (SCS-CN, SOL_K, SLSOIL) during the drought periods. The SWAT water quality calibration needs to be considered for the movement of SS and nutrients transport especially focusing on the drought characteristics.

• Economic and Environmental Geology
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• v.46 no.6
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• pp.545-559
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• 2013

Until now, research achievements of groundwater such as groundwater to depth distribution, usage, the available amount of development, water quality have been written in the watershed units($25{\sim}250km^2$). However, complex topography and geology, and the rivers of our country does not fit. And a clear management standards have not been able to present measures in groundwater quantity, water quality management such as rainfall, groundwater, utilization, water quality, pollution, etc. Therefore, in this study, the classification criterion of subwatershed unit($2.5{\sim}25km^2$), which is suitable for topography and geology of Korea, for rainfall-rating, groundwater level-rating, groundwater pollution-rating, groundwater quality-rating presented and proved its efficiency by applying in Hampyeong-Gun area.