• Journal of Environmental Science International
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• v.7 no.2
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• pp.217-222
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• 1998

Organics matters including algae are the major contaminants of Nak-dong river and it's concentration Is more Increasing now. The use of coagulants has been Incresed for the effective treatment of drinking water, and aluminum coagulants have been the most widely used in raw water treatment. However, when inorganic metal coagulant is excessively used for long period, it would result in secondary problems, such as increasing sludge production, enhancing the cost of water treatment process, and increasing concentration of residual metal, especially aluminum. Therefore, recently. in order to reduce the use of metal coagulant and enhance the coagulation effectiveness, several alternative coagulants, such as polymeric Inorganic coagulants and organic polymers, have been used In water treatment plants. The objectives of thins research were (11 to determine optimum dosage concentration and compare the coajuiation efnciency at various pH ranees with alum alone, alum+cationic polymer, and alum+anlonlc polymer, (21 to evaluate the amount of alum reduced by using organic polymer, (31 to maximize removal officiency of organic matter and minimize the concentration of residual aluminum.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.4
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• pp.539-544
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• 2011

The relative focus about phosphorus (P) which causes eutrophication characterized by increased growth of undesirable algae has increased in recent years. Phosphorus forms in soil and water include both organic and inorganic forms. There are also a large number of soil P determination methods that have been designed to account for various types of P and mechanisms controlling the chemistry of P in soil, water, and residual materials for environmentally relevant forms of P. However, phosphorus forms in soil, water, and residual materials are also difficult to standardize with any reasonable consensus, due to the number of different disciplines involved. Hence, it is essential to accurately define how P can be measured in soil, water, or residual material samples to avoid potential misinterpretations or inappropriate recommendations in determining amount and types of P. Therefore, we reviewed the testing methods which have appeared in the scientific literature to provide an overview of the soil test P most commonly used.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.8 no.1
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• pp.19-24
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• 2012

This paper presents the results of finite element analysis for the effects of hydrostatic test and operating condition on the weld residual stress at dissimilar metal weld of a pressurizer safety nozzle in a nuclear power plant. For the study, the weld residual stress at ambient condition was analyzed using ABAQUS in the first place. After the weld residual stress analysis, the hydrostatic test condition and operating condition was applied to the same model one after another. The weld residual stress was observed to change due to the successive hydrostatic test and operating condition. The axial residual stresses on inner surface of the dissimilar metal weld and HAZ region were decreased by hydrostatic test and operating condition, which gives beneficial effect on preventing primary water stress corrosion cracking.

• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.45-51
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• 2001

In order to clarify the seasonal variation of the residual current and the material transportation process in Hiroshima Bay, JAPAN, the real-time simulation of residual current and particle tracking by using the Euler-Lagrange model were carried out. The calculated tidal current, water temperature, and salinity showed good agreement with the observed ones. The residual currents showed a southward flow pattern at the upper layer, and a northward flow pattern at the lower layer. The flow structure of the residual current in Hiroshima Bay is an estuarine circulation affected by density flow and wind driven current. The residual current plays an important role of material transportation in the bay.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.313-315
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• 2006

Proper water management is important to achieve high performance and durability of Polymer electrolyte fuel cell (PEFC). Among various stack components, gas diffusion layer (GDL) is considered as a core part to determine the gas and water transportation in a cell. To optimize the water management, the changes of properties as well as basic properties of GDLs were investigated before and after clamping of colls. Thickness, electric conductivity, porosity, hydroppobicity etc. were characterized by the same criteria. The amount of residual water after cell operation also was compared by direct measuring of weight. Based on the amount of residual water the endurance on the freeze condition was evaluated.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1369-1376
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• 2005

In case of the drainage type tunnel, the residual water pressure is likely to act on the tunnel lining due to the decrease of water-passing capacity of the filter material. Therefore, this study discussions a method to predict the lining load with the consideration of water passing capacity of the filter material through the literature review and numerical analysis. It is expected from the results of case studies that the design load acting on the concrete lining in the drainage type tunnel could be assumed to be about 50% of the hydrostatic water pressure in steady-state ground-water condition.

• Journal of Environmental Science International
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• v.7 no.3
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• pp.311-320
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• 1998

The volume transport and turnover time of the Deukryang Bay. located at the southern area of Korea, were calculated based on the current meter(RCM-7,ACM 16M) data observed at the three gateways of the tegrating observed data and then averaging on time. dangdo and Kogumdo. The total water volume transports through three entrances of the bay in May and October were $3.9{\times}10-2Sv, 3.4{\times}10^{-2}Sv(1Sv=10^6m^3s^{-1}$) and turnover time were 0.97day, 1.12day, respectively. Semidiurnal tides were predominant (70~85%). The water volume transports by residual currents were 2~4% of total water volume transports . The average fraction of fresh water calculated by tidal prism method using salinity difference between inflow current and outflow current through three entrances In Deukryang Bay was about 0.06% of total volume and the flushing time of fresh water was estimated as 0.97day.

• Journal of Korea Water Resources Association
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• v.56 no.11
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• pp.705-720
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• 2023

In South Korea, ongoing incidents related to drinking water quality have eroded consumer trust. Specifically, beyond quality incidents, there have been complaints about taste, odor, and other issues stemming from the presence of chlorine. To address this, water service operators are employing various management strategies from both temporal (scheduling) and spatial (rechlorination) perspectives to ensure uniform and safe distribution of chlorine residuals. In this study, we focus on the optimal monthly management of chlorine residuals, based on water distribution network analysis. Water quality reaction coefficients, including bulk fluid and wall reaction coefficients, were estimated through lab-scale tests and EPANET water quality simulations, respectively, accounting for temperature variations in a large-scale water distribution network. Utilizing these estimated coefficients, we examined the monthly variations in chlorine residual distribution under different chlorine injection conditions. The results indicate that the efficient concentration for chlorine injection, which satisfies the residual chlorine limit range, varies with temperature changes. Consequently, it is imperative to establish a specific and quantitative chlorine injection plan that considers the accurate spatial distribution of monthly chlorine residuals.

• Journal of Environmental Health Sciences
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• v.44 no.4
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• pp.323-329
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• 2018

Objectives: The purpose of this study is to investigate the water quality of 16 golf course ponds located in northern areas Gyeonggi province by investigating residual pesticides, organic matters (BOD, TOC) and nutrients (TN, TP). Methods: The result data for the residual pesticides were used from 2014 to 2017. and other result data were used for April and July in 2017. The residual pesticides analytical method was based on 'Golf course residual pesticides inspection method', The others analytical method was based on 'The water pollution process test standard' Results: Very toxic pesticides and banned pesticides were not detected but general pesticides were detected. In case of the water quality of the golf course pond was applied to the lake water quality standard. In April the average TOC concentration was V grade to 6.46 mg/L, TP V grade to 0.13 mg/L, TN VI grade to 1.6 mg/L, In July TOC average concentration was VI grade to 8.65 mg/L, TP VI grade to 0.17 mg/L, TN V to 1.5 mg/L. All TN and TP concentrations corresponded to eutrophication. Compared with lake water quality monitoring, the concentrations of BOD, TOC and TP were high but the TN concentration was low in April and July. Conclusions: It is considered that water quality managements are necessary for the golf course pond. The first reason is that the pollutants of pond are discarded to river during rainfall and act as pollution sources. The second reason is that the golf course users are uncomfortable because of odor caused by the pollutants of the pond.

• Journal of the Korean GEO-environmental Society
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• v.9 no.3
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• pp.17-28
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• 2008

In this study, the residual strength prediction models were proposed by measuring various residual strength according to pit characteristics for metallic water pipes such as cast iron pipe (CIP), ductile iron pipe (DIP), and steel pipe (SP). The exponential prediction model was better fitted to measured residual tensile strength for CIP. In case of DIP and SP, the prediction model using loss of strength was more exactly predicted compared with other model types. The fracture toughness were averagely $40.46kgf/mm^2{\sqrt{mm}}$ for CIP, $85.27kgf/mm^2{\sqrt{mm}}$ for DIP, and $92.27kgf/mm^2{\sqrt{mm}}$ for SP, the determination coefficient ($R^2$) of between measured residual tensile strength and predicted values for residual strength prediction models using fracture toughness was estimated from 0.44 to 0.86. Especially, the proposed residual tensile strength prediction models were applied for the verification and reliability to CIPs and DIPs at 14 sites. The determination coefficient ($R^2$) between measured residual tensile strength and predicted values was estimated from 0.76 to 0.78. Therefore it was thought that the proposed residual tensile strength models could help to support resonable and economical decision of rehabilitation/replacement.