• Journal of the Korean Solar Energy Society
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• v.31 no.3
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• pp.23-28
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• 2011

In this study, the ejector design was modeled using Fluent 6.3 of FVM(Finite Volume Method) CFD(Computational Fluid Dynamics) techniques to resolve the flow dynamics in the ejector. A vacuum system with the ejector has been widely used because of its simple construction and easy maintenance. Ejector is the main part of the desalination system, of which designs determine the efficiency of system. The effects of the ejector was investigated geometry and the operating conditions in the hydraulic characteristics. The ejector consists mainly of a nozzle, suction chamber, mixing tube (throat), diffuser and draft tube. Liquid is supplied to the ejector nozzle, the fast liquid jet produced by the nozzle entrains and the non condensable gas was sucked into the mixing tube. The multiphase CFD modeling was carried out to determine the hydrodynamic characteristics of seawater-air ejector. Condition of the simulation was varied in entrance mass flow rate (1kg/s, 1.5kg/s, 2kg/s, 2.5kg/s, 3kg/s), and position of driving nozzle was located from the central axis of the suction at -10mm, 0mm, 10mm, 20mm, 30mm.. Asaresult, suction flow velocity has the highest value in central axis of the suction.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.459-459
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• 2011

전 세계적으로 이용 가능한 수자원이 한정되어 있는데 반해 기후변화, 인구증가에 따른 물 부족 사태는 심각해져 가고 있다. 이에 따른 대체수자원의 개발이 지속적으로 요구되고 있으며, 하수재 이용과 더불어 가장 큰 성장세를 보이고 있는 해수담수화는 이미 국내외에서 주요 용수 공급원으로 이용되고 있다. 하지만, 현재 국내에선 해수담수화 플랜트 기술 연구에 비해 해외 시장에 대한 연구는 미흡하기 때문에, 국내 기업의 해외시장 진출 지원이 취약한 실정이다. 본 연구에서는 Frost & Sullivan의 2004년 자료를 기초로 하여 남부유럽, 북아프리카, 중동, 페르시아만 연안 6개국, 사우디아라비아 지역 37개 국가를 대상으로 해수담수화 수익성 평가를 하였다. 조사 기간은 2000년부터 2010년까지며, 각 지역별 연 수익금 및 증가율을 조사하였다. 조사 결과 5개 지역 모두 2010년까지 모두 증가 추세를 보였으며, 각 지역마다 증가율은 다르게 나타났다. 또한 분석 결과의 신뢰성 확보를 위해 Frost & Sullivan의 수익성 평가 자료와 Global Water Intelligence(GWI)에서 2010년도에 발간한 Desalination Market(2010)의 해수담수화 자본지출 (CAPEX)과 비교 분석하였다. 비교 분석한 지역은 5개 지역과 각 지역에서 한 개의 국가를 선정하여 총 5개 국가를 대상으로 하였으며, 기간은 2007년부터 2010년까지 비교 분석하였다. 분석 결과 2007년부터 2010년까지 북아프리카, 사우디아라비아를 제외한 해수담수화 수익금이 증가할 것으로 예측한 세 개 지역의 해수담수화 자본지출(CAPEX)이 모두 증가된 것으로 나타났으며, 비교기간 동안 해수담수화 수익금이 하강할 것으로 나타난 북아프리카의 알제리는 해수담수화 자본지출(CAPEX)이 실제로 하강했던 것으로 나타났다. 하지만, 사우디아라비아의 경우 해수담수화 수익금은 상승할 것으로 나타났으나, 자본지출금액은 하강한 것으로 나타났다. 또한 시장 증대 요인 및 억제 요인에 대한 조사 결과 해수담수화 시장 증대 요인은 5개 지역 모두 물 부족에 따른 영향이 가장 큰 것으로 나타났으며, 사우디아라비아의 경우 지하수자원 부족에 대한 영향이 가장 큰 것으로 나타났다. 이는 기후변화에 따른 강우사상 변화, 인구 증가에 따른 것으로 판단된다. 또한 시장 억제 요인으로는 남부유럽을 제외한 4개 지역이 정치적 분란인 것으로 나타났다.

• Nuclear Engineering and Technology
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• v.31 no.5
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• pp.506-511
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• 1999

The pilot system for radioactive liquid laundry waste was developed with treatment capacity, 1ton/hr and set up in the Yong Kwang unit #4. The system is composed of tank module, RO systems and a UV/$H_2O$$_2$photo-oxidation unit. The RO system consists of the BW unit (low-pressure RO for brackish water desalination) and the SW unit (high-pressure RO for seawater desalination). The BW unit possesses 4 RO membranes and it can reduce the feed water volume down to 1/10. This concentrated feed water can be reduced again up to 1/10 in its volume in the SW unit composed of 4 RO membranes. The UV/$H_2O$$_2$ photo-oxidation process unit was used for the detergent degradation. The operation of the pilot system was carried out and verified in its capability through the continuous operation and concentration operation using the actual liquid waste from the power plant. The design criteria and data for industrialization were yielded. The efficiency of the UV/$H_2O$$_2$ photo-oxidation process and the optimum operational procedure were evaluated. The decontamination factors for radioactive cobalt and cesium were measured. This on-site test showed the experimental result in the DF$\geq$300 and volume reduction factor$\geq$100.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.4
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• pp.293-300
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• 2021

Recently, various researches have been studied, such as water treatment, water reuse, and seawater desalination using CDI (Capacitive deionization) technology. Also, applications like MCDI (Membrane capacitive deionization), FCDI (Flow-capacitive deionization), and hybrid CDI have been actively studied. This study tried to investigate various factors by an experiment on the TDS (Total dissolved solids) removal characteristics using MCDI module in aqueous solution. As a result of the TDS concentration of feed water from 500 to 2,000 mg/L, the MCDI cell broke through faster when the higher TDS concentration. In the case of TDS concentration according to the various flow rate, 100 mL/min was stable. In addition, there was no significant difference in the desorption efficiency according to the TDS concentration and method of backwash water used for desorption. As a result of using concentrated water for desorption, stable adsorption efficiency was shown. In the case of the MCDI module, the ions of the bulk solution which is escaped from the MCDI cell to the spacer during the desorption process are more important than the concentration of ions during desorption. Therefore, the MCDI process can get a larger amount of treated water than the CDI process. Also, prepare a plan that can be operated insensitive to the TDS concentration of backwash water for desorption.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.216-222
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• 2021

This is an experiment to complement new ways of using concentrated water discharged from the seawater desalination plant. In this study, metakaolin, which has excellent chloride ion immobilization effect, was used as the main binder, and 10% and 20% of calcium oxide were substituted with the activator. In addition, tap-water(TW) and reverse osmosis brine water(RW) were used as mixed water. As a result of the experiment, the mixture using RW showed higher compressive strength than TW. It also showed low water absorption and high density. In the mixture using RW as mixed water, a hydration reaction substance called Friedel's salt could be observed. Considering the corrosion problem of steel, RW is considered to be applicable to products such as non-reinforced concrete, brick, and curb stone. Through this study, it is thought that it is meaningful to propose a new application method other than the ocean release of RW.

• Membrane Journal
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• v.32 no.2
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• pp.91-99
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• 2022

It is a global challenge to fulfill the demand for clean water at an affordable cost to all the strata of the population. Desalination of seawater as well as brackish water by the membrane separation process is a well-established and cost-efficient method. However, there is still inherent problem of membrane fouling, disposal of the reject as well as a capital-intensive process. While electrodialysis (ED) is a membrane-based separation process in which a driving force is the potential difference. The advantages of ED process are excellent efficiency and low operation cost. Ion exchange membrane (IEM) used in the ED process needs to have higher chemical and thermal stability along with excellent mechanical strength for long-term use without losing its efficiency. The ion exchange capacity of the ED membrane is largely dependent on the conductivity of IEMs. In this review, the modification strategy of the pristine membrane to enhance the stability and ion conductivity of cation exchange membrane (CEM) and anion exchange membrane (AEM) is discussed.

• Korean Journal of Ecology and Environment
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• v.56 no.3
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• pp.187-195
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• 2023

Almost all of the water from agricultural dams located to the upper of the Yeongsan river is supplied as irrigation water for farmland and thus is not discharged to the main stream of the river. Also, most of the irrigation water does not return to the river after use, adding to the lack of flow in the main stream. As a result, the water quality and aquatic health of the river have become the poorest among the four major rivers in Korea. Therefore, in this study, several strategies for water quality improvement of the river were developed considering pollution reduction and flow rate increase, and their effect analysis was performed using a water quality model. The results of this study showed that the target water quality of the Yeongsan river could be achieved if flow increase strategies (FISs) are intensively pursued in parallel with pollution reduction. The reason is because the water quality of the river has been steadily improved through pollution reduction but this method is now nearing the limit. In addition, rainfall-related FISs such as dam construction and water distribution adjustment may be less effective or lost if a megadrought continues due to climate change and then rainfall does not occur for a long time. Therefore, in the future, if the application conditions for the FISs are similar, the seawater desalination facility, which is independent of rainfall, should be considered as the priority installation target among the FISs. The reason is that seawater desalination facilities can replace the water supply function of dams, which are difficult to newly build in Korea, and can be useful as a climate change adaptation facility by preventing water-related disasters in the event of a long-term megadrought.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.3
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• pp.351-357
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• 2022

A conventional seawater reverse osmosis (SWRO) and a forward osmosis (FO) and reverse osmosis (RO) hybrid process to produce 1,000 m³/d of fresh water, were designed and compared in terms of carbon emission. When FO was adapted for the osmotic dilution, the required pressure for RO decreases, and thus energy consumption decreases. The decrease in carbon emission by decreased energy consumption (up to -0.73 kgCO₂/m³ using coal as the energy source) was compared with the increase in carbon emission by the FO system (+0.16 kgCO₂/m³), which is a function of various factors such as the number of FO modules and energy consumption. The comparison revealed that the FO-RO process causes less carbon emission compared with the SWRO process when the energy sources are coal and oil. However, if energy sources with low carbon emission such as solar, wind, and nuclear energy are selected, the carbon emission of the FO-RO process becomes higher than that of the SWRO process. This implies that the type of energy source is a key factor to determine the necessity of the FO-RO process from the aspect of carbon emission.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.6
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• pp.607-613
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• 2010

A seawater distiller, in which the waste heat from a portable electric generator was used, with a multiple-effect diffusion still was designed. The waste gas from small generators commonly used in islands has not yet been used because it has less thermal energy; however, this waste gas can be used as a heat source for small-capacity distillers and as an additional heat source for solar stills. The proposed distiller comprises a series of closely spaced parallel partitions that are placed in contact with saline-soaked wicks. In the distiller, evaporation and condensation processes are repeated to recycle the thermal energy for increasing the distillate productivity. Experimental results show that the proposed distiller with only one-effect still can produce at least 6.7 kg/day of distilled water; the proposed distiller with a ten-effect still is expected to produce 43 kg/day of distilled water. This amount of distillate is approximately four times the maximum daily productivity of the solar stills, as determined in outdoor experiments.

• KCID journal
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• v.18 no.1
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• pp.44-57
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• 2011

The status of fishway installed in domestic dikes showed a cascade types and sluice gate types 36% (four sites) and 64% (seven sites), respectively. Fishway of cascade type was constructed four sites (Iweon, Busa, Geum river, Haenam) and only Geum river was one of them has operated much more effectively since remodeling in a fishway and fishways of the others was not operated because of several problems like a desalination, a shortage of inflow water and variation of management elevation. Fishway of sluice gate type was installed seven sites and three sites (Yeongsan, Yeongam, Geumho) one of them were continuously operated until now. This results has a interesting interpretations. Prolonged discharge of inductive water from fishway can positively affect not only ascending of fishes but also fish fauna of around of the sea. The others of a sluice gate fishway were not operated because of seawater circulation through sluice gate until now. The closed reasons of fishway in domestic dikes may be summarized as follows: impassibility of sluice gate open by shortage of inflow water, problem of proper operating by long distance of between fishway and management office, absence of operating manual, seawater circulation, lack of fishway operating awareness. It was takes a long time for solution of hardware part but software part can be to find the answer through making a fishway operation manual and development of education program for manager. In this paper we deal with fishway in domestic dikes. Proper fishway control by manager was essential for ascending of migration fishes especially at fishway installed in dikes. Thus it was necessary to make manual for fishway operation and effort of continuously maintenance.