• Membrane Journal
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• v.1 no.1
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• pp.78-95
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• 1991

Water factory 21(WF 2) in Orange County California, is a advanced wastewater treatment(AWT) plant designed to reclaim biologically treated munidpal wastewater for injection into a seawater barrier system. Processes included are lime treatment air stripping, filtration, activated carbon adsorption, reverse osmosis(RO), and chlorination. The effectiveness of each treatment process is presented including pretreatment, RO dimineralization. The data collected show that the processes, including RO, used at WF-21 are capable of producing a very high quality water on a reliable basis. Treatment reduced all contaminants, to levels below national primary drinldng water regulation maximum contaminant levels. It was found that lime clarified secondary effluent can be used as feedwater to a RO dimineralizer. Experiments with new low pressure membrane(250psi) show great potential for reducing RO cost.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.175.2-175.2
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• 2011

바나듐 3, 4, 5가 이온은 공기 중에서 안정하지만, 바나듐 2가 이온은 쉽게 산화된다. 그러므로 바나듐 2가 이온이 담겨져 있는 음극 탱크가 공기와 접촉하지 않게 하는 것이 중요하다. 충전 중 음극 탱크에 공기가 침투되면, 바나듐 2가 이온은 3가 이온으로 산화되기 때문에 음극과 양극의 전해질에 불균형을 초래한다. 이러한 불균형은 바나듐 레독스 흐름전지 용량저하의 원인이 된다. 본 연구에서는 공기 중 2가 이온 산화에 의한 전해질의 불균형 현상을 쉽게 보여주기 위해, 공기노출과 차단조건에서 충방전 중에 발생한 음극과 양극의 바나듐 이온 상태변화량을 UV-Visible spectrophotometer를 이용해 정량적으로 분석하였다. 분석 결과, 공기노출 조건에서 음극의 충전 시, 충방전 cycle이 진행 될수록 바나듐 2가 이온의 양이 현격히 줄어들었지만, 공기차단 조건에서는 2가 이온의 양이 공기노출 조건보다 훨씬 더 적게 줄어들었다. 즉, 공기차단 조건에서는 바나듐 2가 이온이 3가로 산화되지 않아서 음극의 충전 후 바나듐 3가에서 2가로 전환되는 양이 공기노출 조건보다 더 많은 것을 확인할 수 있었다. 이러한 영향으로 인해, 충방전 10th cycle을 진행해 본 결과, 공기차단 조건에서는 충방전 용량감소가 거의 없었지만 공기노출 조건에서는 현격한 충방전 용량 감소를 보였다.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.129-142
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• 2016

This study evaluates the sectoral effects of the regeneration of the idle space and aims to analyze the impact relationship and structure with the quality of residents's life and local economy revitalization. this study verifies the 8 hypotheses from total 11 ones through the PLS structural equation model and suitability test for setting the hypothesis and statistical significance test. The results can be summarized into 3 parts. First, If physical, social and cultural aspects should be considered, Regeneration of idle space could meet the 2 pasts such as quality of residents life and local economy revitalization at the same time. Secondly, the regeneration of idle space from environmental aspect should be led by the local government and let it's effect leaded to local economy revitalization through the collaboration of private and public sector. Finally, it should promote the quality of resident's life and let the satisfaction linked to cyclical effects with local economy revitalization. This study has an significance that it provides the theoretical basis for regeneration of idle space and it is an empirical study for impact structure model.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.87-96
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• 2006

Selectivity estimation is one of the query optimization techniques. It is difficult for the previous selectivity estimation techniques for moving objects to apply the position change of moving objects to synopsis. Therefore, they result in much error when estimating selectivity for queries, because they are based on the extended spatial synopsis which does not consider the property of the moving objects. In order to reduce the estimation error, the existing techniques should often rebuild the synopsis. Consequently problem occurs, that is, the whole database should be read frequently. In this paper, we proposed a moving object histogram method based on quad tree to develop a selectivity estimation technique for moving object queries. We then analyzed the performance of the proposed method through the implementation and evaluation of the proposed method. Our method can be used in various location management systems such as vehicle location tracking systems, location based services, telematics services, emergency rescue service, etc in which the location information of moving objects changes over time.

• Journal of KIISE:Software and Applications
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• v.29 no.3
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• pp.145-155
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• 2002

In content-based image retrieval (CBIR), most conventional approaches assume a linear relationship between different features and require users themselves to assign the appropriate weights to each feature. However, the linear relationship assumed between the features is too restricted to accurately represent high-level concepts and the intricacies of human perception. In this paper, a neural network-based image retrieval (NNIR) model is proposed. It has been developed based on a human-computer interaction approach to CBIR using a radial basis function network (RBFN). By using the RBFN, this approach determines the nonlinear relationship between features and it allows the user to select an initial query image and search incrementally the target images via relevance feedback so that more accurate similarity comparison between images can be supported. The experiment was performed to calculate the level of recall and precision based on a database that contains 1,015 images and consists of 145 classes. The experimental results showed that the recall and level of the proposed approach were 93.45% and 80.61% respectively, which is superior than precision the existing approaches such as the linearly combining approach, the rank-based method, and the backpropagation algorithm-based method.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11c
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• pp.1721-1724
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• 2002

본 논문에서는 기존의 서버 기반 데이터 웨어하우스 유지 전략에 대한 문제점들을 해결하기 위해 클라이언트 기반 웹 하우스 유지 전략을 제시한다. 소스 시스템에서 데이터 갱신이 발생했을 경우 브라우져 모니터를 통해 자동적으로 웹하우스에 실시간 반영하도록 하여 모든 사용자 요청을 서버에서 처리하는 부담을 줄이고 사용자가 많더라도 웹하우스 시스템의 처리부담을 최소화할 수 있도록 클라이언트에서는 결과 데이타 재사용/질의 재생성을 사용하여 서버의 자원 사용을 최소화할 수 있도록 하였다. 모든 클라이언트 프로그램은 자동적으로 설치되고 관리되므로 프로그램이 변동되더라고 쉽게 유지될 수 있으며 소스 시스템에는 어떠한 처리 부담도, 어떠한 프로그램도 설치하지 않기 때문에 실제 비즈니스 현실에서 적용하기가 용이하다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.94-96
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• 2002

본 논문에서는 기존치 서버 기반 데이터 웨어하우스 유지 전략에 대한 문제점들을 해결하기 위해 클라이언트 기반 웹 하우스 유지 전략을 제시한다. 소스 시스템에서 데이터 갱신이 발생했을 경우 브라우져 모니터를 통해 자동적으로 웹하우스에 실시간 반영하도록 하여 모든 사용자 요청을 서버에서 처리하는 부담을 줄이고 사용자가 많더라도 웹하우스 시스템의 처리부담을 최소화할 수 있도록 클라이언트에서는 결과 데이타 재사용/질의 재생성을 사용하여 서버의 자원 사용을 최소화 할 수 있도록 하였다. 모든 클라이언트 프로그램은 자동적으로 설치되고 관리되므로 프로그램이 변동되더라도 쉽게 유지될 수 있으며 소스 시스템에는 어떠한 처리 부담도, 어떠한 프로그램도 설치하지 않기 때문에 실제 비즈니스 현실에서 적용하기가 용이하다.

• Clean Technology
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• v.27 no.2
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• pp.152-159
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• 2021

Volatile organic compounds (VOCs) occur in indoor and outdoor industrial and urban areas and cause environmental problems. Malodorous VOCs, along with aesthetic discomfort, can have a serious effect on the human body. Compared with the existing method of reducing malodorous VOCs, a wet scrubbing method using an electrolytic oxidant has the advantage of reducing pollutants and regenerating oxidants. This study investigated the optimal conditions for producing OCl^-, a chlorine-oxidant. Experiments were conducted by changing the type of anode and cathode electrode, the type of electrolyte, the concentration of electrolytes, and the current density. With Ti/IrO₂ as the anode electrode and Ti as the cathode electrode, OClproduction was highest and most stable. Although OCl^- production was similar with the use of KCl or NaCl, NaCl is preferable because it is cheap and easy to obtain. The effect of NaCl concentration and current density was examined, and the OCl^- production rate and concentration were highest at 0.75 M NaCl and 0.03 A cm^-2. However, considering the cost of electric power, OCl^- production under the conditions of 1.00 M NaCl and 0.01 A cm^-2 was most effective among the conditions examined. It is desirable to produce OCl^- by adjusting the current density in accordance with the concentration and characteristics of pollutants.

• Journal of KIISE:Databases
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• v.30 no.3
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• pp.252-272
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• 2003

The view mechanism provides users with appropriate portions of database through data filtering and integration. In the Web era where information proliferates, the view concept is also useful for XML, a future standard for data exchange on the Web. This paper proposes a method of implementing XML views called XML view indexing, whereby XML view xv is represented as an XML view index(XVI) which is a structure containing the identifiers of xv's underlying XML elements as well as the information on xv. Since XVI for xv stores just the identifiers of the XML elements but not the elements themselves, when a user requests to retrieve xv, its XVI should be materialized against xv's underlying XML documents. Also an efficient algorithm to incrementally maintain consistency of XVI given a update of xv's underlying XML documents is required. This paper proposes and implements data structures and algorithms for XML view indexing. The performance experiments on XML view indexing reveal that it outperforms view recomputation for repeated accesses to the view, and requires as much as about 30 times less storage space compared to XML view materialization though the latter takes less time for repeated accesses to the view due to no need of materialization.

• The KIPS Transactions:PartD
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• v.8D no.4
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• pp.327-338
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• 2001

The view can provide the user an appropriate portion of the database through data integration and filtering. Views can be materialized for query performance improvement, and in that cse, their consistency needs to be maintained against the updates of the underlying data. They can be either recomputed or incrementally refreshed by reflecting the relevant updates. Since XML could represent the structural information of the documents, for the XML materialized views, new techniques that differ from the previous ones for incrementally refreshing the relational views are required. In this paper, we propose a framework of XML materialized view management where the XML view derived from the underlying XML documents are materialized and incrementally refreshed against the updates of the underlying documents.