• Journal of Korean Society on Water Environment
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• v.32 no.5
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• pp.442-449
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• 2016

The goal of this study is to provide basic data to establish a foundation for the provision of safe drinkable water. The raw water of natural mineral water was analyzed to determine the quantities of anions (F^-, Cl^-, NO_3-N^-, and SO₄^2- ) and cations (Ca²⁺, K⁺, Mg²⁺, and Na⁺) during the former and latter half of 2016. Analysis of the current quality of the raw water of natural mineral water among domestic manufacturers showed average anions contents of 0.46mg/L of fluorine, 8mg/L of chlorine ion, 1.5mg/L of nitrate nitrogen, and 12mg/L of sulfate ion. While the fluorine content was greater than the water quality criterion of 2.0mg/L at four points, the fluorine level was overall stable. The average cations contents included 21.3mg/L of calcium, 1.0mg/L of potassium, 3.4mg/L of magnesium, and 9.6mg/L of sodium. The chemical characteristics were compared among the major ions, and the results are presented in a piper diagram. The content ratio of cations was in the order of Ca²⁺> Na⁺>Mg²⁺>K⁺, whereas that of anions was in the order of SO₄^2->Cl^->NO_3-N^->F^-. While the cations were slightly scattered, the anions were generally concentrated except for at a few points. The Ca-Na-HCO₃ type was dominant overall in water sources from diorite, gneiss, and granite, while the Na-Mg-Ca-HCO₃-Cl type was dominant in basalt sources. Mineral water manufacturers source their water under various conditions, including in-hole casing, excavation depth, and contact state of bedrock; even within the same rocky area, some differences in the water quality type can occur. When the depth of the water source was taken into account, the mean anions contents of F^-, Cl^-, NO_3-N^-, and SO₄^2- were similar, with no significant differences according to depth. Of the cations, K⁺ and Na⁺ showed no significant differences across all the tubular wells, whereas Ca²⁺ and Mg²⁺ decreased in content with depth.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.2
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• pp.149-159
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• 2017

It is considered necessary to renewal a considerable number of water supply facilities in Korea because they began to be intensively buried in the period of rapid economic growth. Accordingly, local water providers are required to take measures against this situation, but they have currently been caught in a vicious circle of the lack of budget spent in renewing water supply facilities because county-based small-scale local water supply cannot afford to cover annual expenditures with their revenues from water rates. Therefore, this study developed an optimal renewal planning model capable of achieving a balance of financial revenue and expenditure in local water supply using nonlinear programming and furthermore of minimizing the total cost incurred during the analysis. To this end, this study selected the water supply area located in County Y as a research area to build the financial revenue and expenditure and used Solver function provided by Microsoft Excel to use nonlinear programming. As a result, this study developed an optimal renewal planning model minimizing incurred costs in consideration of 6 items in the financial revenue and expenditure. The optimal renewal plan was modeled according to the available annual budget. As a result, this study proposed SICD, a scenario to minimize total costs from the perspective of water suppliers, and SITS, a scenario to minimize the increase in water rates from the perspective of consumers. It can be said that the method proposed in this study is the core of the optimal financial and renewal plans as a final stage of asset management for water supply facilities. Therefore, it is considered possible for local water providers to use the method proposed in this study according to circumstances for the asset management of water supply facilities.

• Journal of Korea Water Resources Association
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• v.55 no.7
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• pp.505-513
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• 2022

Recently, uncertainty in predicting available water resources is gradually increasing due to climate change and extreme weather conditions. Social interest in water management such as flood and drought prevention is also increasing, and after the unification of water management implemented in 2018, domestic water management is facing a major turning point. As part of such strengthening of water management capabilities, various studies are being conducted to utilize a hydropower dam for flood control and water supply purposes, which was mainly operated for hydroelectric power generation. However, since the dam evaluation methods developed based on a multi-purpose dam are being applied to hydropower dams, an additional evaluation approach that can consider the characteristics of hydropower dams is required. In this study, a new water supply capacity evaluation method is presented in consideration of the operational characteristics of hydropower dams in terms of water supply, and a connected reservoir simulation method is proposed to evaluate the comprehensive water supply capacity of a dam group operating in a river basin. The presented method was applied to the hydropower dams located in the Bukhan River basin, and the results of the water supply yield of individual dams and multi-reservoir systems were compared and analyzed. In the future, the role of hydropower dams for water supply during drought is expected to become more important, and this study can be used for sustainable domestic water management research using hydropower dams.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.2
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• pp.53-62
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• 2020

The purpose of this study is to estimate the channel water loss of agricultural water supply in the command areas belong to Yechon irrigation channel of Gyeongcheon reservoir located Mungyeong-si, which area experienced a severe drought in 2015. The channel water loss was estimated by comparison of the irrigation water requirements (IWR) and agricultural water supply of the field data from 2012 to 2015. Further analysis was conducted to define the conveyance loss estimated based on the leakage holes and illegal pumping spots investigated through the field survey, and the distribution loss obtained by subtracting conveyance loss from the channel water loss. The annual rainfall decreased gradually, but the contribution of effective rainfall, available rain water to crop, increased to IWR during the study period. These phenomena resulted in the increase of agricultural water supply, and hence made greater the channel water loss simultaneously. The average channel water losses estimated as 36.8 % with 7.1 % of the conveyance loss and 29.7 % of distribution loss respectively. The distribution loss seems to be related to total number of rainy days, and irrigation schedules, while the conveyance loss was caused by irrigation channel aging conditions and illegal intake problems. In order to achieve sustainable agricultural water resources, the channel water loss needs to be reduced through the restoration of aged irrigation facilities and effective water managements in the fields.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.4
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• pp.493-502
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• 2015

In accordance with the Watershed Sewer System Maintenance Plan enforced on February 2, 2013, the different compliance concentration of effluent limit be applied to effluent discharged from public sewage treatment works(PSTWs) in each watershed on the basis of water quality thereof. With the introduction of watershed sewer system, it is necessary to set the compliance concentration of effluent limit for PSTWs situated in the watershed, by region and PSTW size, to achieve water quality criteria for regional watersheds or target water quality under TMDL program. Watershed Environmental Agencies establish the Watershed Sewer System Maintenance Plan and set the compliance concentrations of effluent limit for PSTWs under the plan. The agencies plan to apply tougher effluent BOD concentration limits in Class I to IV areas. Effluent BOD concentration limits will be toughened from 5~10 mg/L to 3 mg/L in class II~III areas, from 10mg/L to 5mg/L in class IV areas. Uniform application of effluent BOD concentration limits to PSTWs in the watershed sewer system need to be complemented considering type of sewage treatment technology employed and watershed characteristics. Therefore, this study presents method to determine the compliance concentration of effluent limit from PSTWs in the watershed.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.5
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• pp.389-398
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• 2018

A nationwide survey of 8 N-nitrosamines in finished water samples from drinking water treatment plants (DWTPs) in Korea was conducted. The samples were pre-treated by solid-phase extraction (SPE) and analyzed using a gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). According to the study results, four N-nitrosamines (NDMA, NDEA, NMOR, NDBA) were detected for three consecutive years, NMEA and NPYR were only found in samples collected in 2013. Two of these N-nitrosamines, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA), have received attention and were the most commonly detected. The concentration of NDMA and NDEA in this study ranged from $0.002{\mu}g/L$ to $0.013{\mu}g/L$ and in $0.001{\mu}g/L$ to $0.008{\mu}g/L$, respectively. In comparison to studies performed in EPA(UCMR2), the concentrations of NDMA (from $0.002{\mu}g/L$ to $0.630{\mu}g/L$) and NDEA (from $0.005{\mu}g/L$ to $0.100{\mu}g/L$) observed in the this study were low.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.535-545
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• 2012

Recently, drinking water quality has significantly improved with the progress of water treatment technologies, however, customer's trust on tap water is still relatively low. Low trust on water quality is mainly due to vague anxiety. Therefore, to improve customer's trust on drinking water quality new strategy such as water safety plan(WSP) which recommended by WHO and IWA should be introduced. WSP can be defined as an approach which uses comprehensive risk assessment and risk management approach that encompasses all steps in water supply from catchment to consumer to ensure the safety of a drinking water supply. In this study, cases on WSP introduction in other countries as well as strategy for the introduction of WSP in Korea were investigated. In addition, recommendations on the improvement of the current water contamination response manual was suggested based on the analysis of the existing manual at a full scale water treatment plant.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.1
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• pp.77-85
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• 2007

One of the most common approaches to achieve better thermal comfort with the radiant floor heating system is supply water temperature control, which is that supply water temperature is varied with outdoor air temperature. But the application of this control method was not easy, because there has been no way to determine the supply water temperature. So in this study, a comprehensive, yet simple calculation method to find out the required supply water temperature is suggested by combining the building heat loss equation and the heat emission model of hydronic radiant floor heating system for single zone. And then using this calculation method, the multizone control method is suggested and confirmed through the thermal simulation. It is shown that indoor air temperature is stably maintained around the set point.

• Fire Science and Engineering
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• v.33 no.5
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• pp.28-36
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• 2019

In the present study, the effects of supply gas and water mist on the heptane pool fire extinguishing performance were investigated using the full cone and hollow cone twin-fluid atomizers. Air or nitrogen of 30 lpm (Liter per minute; L/min) was used as the supply gas, and the experiments were conducted under the water flow rate conditions of 0 lpm (i.e., discharge of air or nitrogen only) and 0.085 lpm (i.e., discharge of water mist with supply gas). Experimental results confirmed that the use of water mist discharge with the supply gas and full cone spray pattern reduced the fire extinguishing time as compared to that of only supply gas discharge and hollow cone spray pattern. In addition, for the discharge of water mist using the full cone twin-fluid atomizer, water mist significantly affected fire extinguishing performance, whereas the effect of the supply gas was less pronounced. On the other hand, for the discharge of water mist using the hollow cone twin-fluid atomizer, the fire extinguishing time was remarkably reduced by the supply of nitrogen, as compared with that of air, indicating that the supply gas as well as water mist can significantly affect fire extinguishing performance.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1318-1321
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• 2005

As recently raw water quality has been polluted as well as its quality has been remarkably varied according to season and region, the precise control of coagulant dosage is being keenly required in water treatment plants. The amount of coagulant is closely related to raw water quality such as turbidity, alkalinity, water temperature, pH, electrical conductivity, etc. Since the optimum quantity of chemicals is not yet finalized, so dosage rate must be decided by using jar test that takes one or two hours. Hereupon, the output signal of stream current and multi-regression on historical data were proposed to be applied to the coagulant dosing control. In consequence of applying the scheme to automatic determination of the dosage rate, it was testified that the determination of dosage rate was very effective in case it is performed as to real-time sensing of water quality and the output signal of stream current.