• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.359-369
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• 2017

Water distribution systems supply drinking water to consumers' taps. Internal corrosion of metallic pipe used in drinking water distribution systems has reduced water quality and led to increased levels of toxic heavy metals such as lead, copper and nickel. These problems have been experienced to varying degrees by water utilities in many countries. North America has successfully managed and controlled pipe corrosion and corrosive water in water distribution system based on various policies, regulations and rules. Practical and engineering guidelines for evaluation of pipe corrosion and determination of treatment options are also provided to assist drinking water supplies. In addition, the corrosion mechanism in water distribution systems, such as the complex effects of physical and chemical parameters on the corrosion pipes has been improved to accurately predict corrosion rates of metallic pipes in actual water distribution systems. This paper reviews various regulations, policy statement, and treatment produces on controlling corrosion in drinking water distribution systems in US and Canada and then offers suggestion for management of corrosive water and pipe corrosion in drinking water distribution system in Korea.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.280-283
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• 1995

In centrifugal barrel finishing, it is easy to establish the optimum working conditions for different workpieces. As they are adjusted in trial and error practically, production efficiency and quality are some- times low In the present paper, firstly, installation of the barrel finishing machine, finishing purpose and working conditions have been analyzed in order to eliminate the defects of the finished surface. Secondly, on the basis of this result, quantity of the water and selection of the media and the compound, etc. have been investigated. As a result, production efficiency and quality have been improved under the specified optimum working conditions. In addition, durability of the media and the compound has been tested experimentally. As a result, it was found that the expected life of the media is about 85 hrs and that of the compound is about 5 hrs. Besides high quality control has been achieved by newly proposed inspection at regular intervals.

• Journal of Korean Society on Water Environment
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• v.35 no.1
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• pp.43-54
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• 2019

The objective of this study was to assess the effect of policies on water quality management based on the changes in pollutants and water quality in Special Water Preservation Area (SWPA) of Lake Paldang watershed from 1990 to 2016. The population, total sewage and flow rate of wastewater in SWPA continuously increased from 1990 to 2016, while the location of new facilities for industrial and livestock facilities has been restricted. However, unlike the buffer zone in which industrial and livestock facilities were continuously reduced after implementing of TMDL, it was found that the effect of land-use regulations on industrial and livestock facilities in SWPA were mitigated by the increase in the size of large facilities. Since 1999 when the emission standard of public sewage treatment plants (STP) was changed, the water quality of Lake Paldang has increased despite the increase of pollutant source. Since emission standard of STP changed in 2012 (BOD 5 mg/L, TP 0.2 mg/L), BOD concentration in Lake Paldang has also improved to the level of water quality in the early 1990s where as TP concentration has remained at its lowest since 1990. BOD and TP average discharge concentration of 43 STP (${\geq}500m^3/day$) in 2016 have been maintained $1.7{\pm}0.7mg/L$ and $0.06{\pm}0.02mg/L$ respectively. While the discharged load of STP in SWPA was decreased by the concentration management, the contribution rate to the total discharged load of non-point pollutants increased to 70 % in 2015, and the contribution rate to the point discharged load of individual treatment facilities increased to 80 %.

• Journal of Environmental Science International
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• v.10 no.2
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• pp.105-111
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• 2001

Improvement of water quality and Investigation of bacterial characteristics have been conducted in a pilot plant using biological activated carbon (BAC) in water treatment process at the downstream of the Nakdong River. Most of water control parameters were highly improved after passing through BAC. Approximately 54% of dissolved organic carbon was removed in coal-based BAC process. Bacterial biomass and bacterial production appeared $9.8{\times}10^8 CFU/g and 7.1mg-C/m^3$.hr in coal-based BAC, respectively. Predominant bacteria species grown in BAC were identified as Pseudomonas, Flavobacterium, Alcaligenes, Acinetobacter and Aeromonas species. Particularly Pseudomonas vesicularis was dominant in both coal-based and coconut-based BACs, while Pseudomonas cepacia was dominant in wood-based BAC.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.453-460
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• 2005

Since late 1970s, water quality monitoring had been performed in Korea by various agencies according to their own needs and objectives. Lacking of consistency in principles, such diverse operation has been producing difficulties in management of information on water quality parameters. These difficulties resulted from the fact that the expansion of monitoring networks had been based not on systematic methodology with considerations on scientifically established planning objectives but on personal experiences and subjective judgments in locating monitoring stations. This study aimed, therefore, to develop a selection methodology for locating monitoring stations to provide various informations on water quality to satisfy various monitoring objectives such as understanding short and long term trends of water quality, monitoring violations to water quality standards, identifying external causes and sources affecting water quality changes, supporting utilization of water resources, examining short-term variations in water quality through a concentrated investigation, estimating pollution loads from each unit watershed, supporting water quality modeling, and establishing informative systems for water resources management. Also, we applied the proposed methodology and presented an improved expansion plan for water quality monitoring networks in the Han River.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.860-870
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• 2010

Long term monthly monitoring data showed that the water quality of streams flowing into Lake Paldang has been improved by various strategy for water. However, the effect of quality on Lake Paldang is still insufficient because of nonpoint source from watershed. In order to evaluate quantifying methods for pollution source and make a suggestion on improvements, Storm Water Management Model (SWMM) was constructed by using data set from the water quality and streamflow monitoring network in the Kyoungan watershed for Total Maximum Daily Loads (TMDLs). Load duration curve (LDC) based on the result of the Kyoungan watershed SWMM indicated that the water quality criterion on $BOD_5$ was often exceeded in up-stream than down-stream. From flowrate-load correlation curve, SS load significantly increased as streamflow increases. 75.3% of streamflow and 62.1% of $BOD_5$ loads is discharged especially in the zone of high flows, but monitoring data set didn't provide proper information about the conditions and the patterns associated with storm events. Therefore, it is necessary to acquire representative data set for comparing hydrograph and pollutograph through monitoring experimental watershed and to establish methods for quantifying point and nonpoint source pollutant loads.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.111-120
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• 2000

In case of constructing concrete structure under water, generally concrete mixed with antiwashout admixture, high range water reducer, or AE-water reducing agent etc has been manufactured to ensure the quality of antiwashout underwater concrete because of being difficulty in ascertaining construction situation by the naked eye. The properties of high quality antiwashout underwater concrete that were aimed at affluent fluidity, workability and the compressive strength of 450 kgf/$\textrm{cm}^2$ at 28 ages using two types of blended cements are following as;(1) Setting time of antiwashout underwater concretes using blended cements was more greatly delayed than that of control concrete, however, was satisfied with criteria value of "Quality standard specification of antiwashout admixture for concrete".(2) As a test results of slump flow, efflux time and box elevation of head, it was found that workability of high quality antiwashout underwater concrete was improved. (3) Heat evolution amount of OPC was 1.5 times as high as that of two types of bended cements in 72 hours. (4) Suspended solids of antiwashout underwater concrete using blended cements was more than that of control concrete, also compressive strength of high quality antiwashout underwater concrete was very low in early age, but was better than that of control concrete as to increasing ages.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.2
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• pp.252-259
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• 2015

The present study was conducted to investigate the efficacy of sweet potato powder (SPP) and water as a fat replacer in low-fat pork patties. Low-fat pork patties were developed by replacing the added fat with combinations of SPP and chilled water. Three different levels of SPP/chilled water viz. 0.5/9.5% (T-1), 1.0/9.0% (T-2), and 1.5/8.5% (T-3) were compared with a control containing 10% animal fat. The quality of low-fat pork patties was evaluated for physico-chemical (pH, emulsion stability, cooking yield, $a_w$), proximate, instrumental colour and textural profile, and sensory attributes. The cooking yield and emulsion stability improved (p<0.05) in all treatments over the control and were highest in T-2. Instrumental texture profile attributes and hardness decreased, whereas cohesiveness increased compared with control, irrespective of SPP level. Dimensional parameters (% gain in height and % decrease in diameter) were better maintained during cooking in the low-fat product than control. The sensory quality attributes juiciness, texture and overall acceptability of T-2 and T-3 were (p<0.05) higher than control. Results concluded that low-fat pork patties with acceptable sensory attributes, improved cooking yield and textural attributes can be successfully developed with the incorporation of a combination of 1.0% SPP and 9.0% chilled water.

• Journal of Korean Society on Water Environment
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• v.36 no.5
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• pp.423-430
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• 2020

To improve the low treatment efficiency of sewage treatment plants, the separated sewer system must be maintained to provide an adequate flow rate and quality of the sewage under the effect of inflow. In this study, data from five locations of Namsuk, Dukgok1, Dukgok2, Kanggu, and Opo were used to conservatively calculate the inflow water volume. The sewer flow and rainfall data were collected in 2017. The factors in the standard method used to calculate the inflow of the combined sewer pipes including "rainy days", "rainfall impact period", and "period for basal sewer" were defined as 3 mm/day, continuous rain for two days, and two weeks prior to the inflow generation, respectively. "Rainy days", "rainfall impact period", and "period for basal sewer" were conservatively adjusted to 5 mm/day, continuous rain for five days, and three weeks prior to the inflow generation, respectively. As a results of the adjustment, the linearity (r²) was improved except for in Dukgok1. This implies that the conservative adjustment made in this study could improve the management quality of sewer pipes. Also, the linear correlation coefficient (a_i) between inflow and rainfall showed a large difference between the target locations, which can be another monitoring factor affecting the quality of sewer pipes. To improve the correlation based on the individual characteristics of the locations in Korea, the automatic algorithm for the inflow calculation should be developed by innovative intellectual technologies for application to the entire national area.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.9
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• pp.887-893
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• 2010

Role of the perforated pipe is to drain the water with equal pressure and velocity through the holes of perforated pipe. The perforated pipe is being used in many processes of water treatment system, however, the design parameter of perforated pipe is not standardized in korea. In this study, we have found the design parameter of perforated pipe in the water treatment system using the Computational Fluid Dynamics (CFD). The uniformity of outflow from the perforated pipe is directly affected according to area ratio (gross area of holes/surface area of the perforated pipe). In other words, the uniformity of outflow is improved as area ratio is smaller. Also, at the same area ratio, the uniformity of outflow is improved as number of holes is increase. Specially, in case of the two holes per length of pipe diameter (2/D) shows the most uniformity of outflow and the best hydraulic with the smaller pressure drop. When the inlet velocity of pipe is about 0.06m/sec, the flux of pipe has decreased as from front to backward. When the inlet velocity is 3 m/s, the flux of pipe has increased as from front to backward.