• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 춘계학술대회 학술발표 논문집
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• pp.7-10
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• 1998

The conventional relational databases have difficulties to efficiently represent various of data because an attribute of a tuple should have only one elementary value. In order to represent ambiguous and imprecious information, fuzzy set and rough set have been gaining acceptance, especially as a tool for knowledge discovery in databases. One of former researches applies only one fuzzy membership value to a tuple. We suggest a more advanced model for data representation by way of applying many membership values to a tuple, i.e. one membership value to each attribute of a tuple.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2006년도 PROCEEDINGS OF JOINT CONFERENCEOF KDISS AND KDAS
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• pp.55-62
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• 2006

Huang proposed a grey-based nearest neighbor approach to predict accurately missing attribute value in 2004. Our study proposes which way to decide the number of nearest neighbors using not only the dong's grey relational grade but also the wen's grey relational grade. Besides, our study uses not an arithmetic(unweighted) mean but a weighted one. Also, GRG is used by a weighted value when we impute a missing values. There are four different methods - DU, DW, WU, WW. The performance of WW(wen's GRG & weighted mean) method is the best of my other methods. It had been proven by Huang that his method was much better than mean imputation method and multiple imputation method. The performance of our study is far superior to that of Huang.

• 정보기술과데이타베이스저널
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• 제6권1호
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• pp.15-25
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• 1999

We propose an extended relational data model which can represent the reliability of data. In this paper, the reliability of data is defined as the reliability of the source, from which the data originated. We represent the reliability of data at the level of attribute values, instead of tuples, then define the selection, product and join operators.

• 정보기술과데이타베이스저널
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• 제6권2호
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• pp.71-86
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• 1999

The performance of relational database is measured by the number of disk accesses necessary to transfer data from disk to main memory. The paper proposes to vertically partition relations into fragments and to allow attribute replication to reduce the number of disk accesses. To reduce the computational time, heuristic search method using genetic algorithm is used. Genetic algorithm used employs a rank-based-sharing fitness function and elitism. Desirable parameters of genetic algorithm are obtained through experiments and used to find the solutions. Solutions of attribute replication and attribute non-replication problems are compared. Optimal solutions obtained by branch and bound method and by heuristic solutions(genetic algorithm) are also discussed. The solution method proposed is able to solve large-sized problems within acceptable time limit and shows solutions near the optimal value.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제3권1호
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• pp.19-30
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• 2014

시맨틱 웹의 확산을 위해 관계형 데이터베이스에 저장된 데이터를 온톨로지로 변환하는 연구가 활발히 진행 중이다. 관계형 데이터베이스에 저장된 데이터를 온톨로지로 변환하기 위한 연구들은 관계형 데이터베이스의 구성 요소와 RDF 구성 요소를 매핑하는 방식인 RDB to RDF 매핑 모델을 주로 사용한다. 하지만 지금까지 제안된 매핑 모델들은 그 표현방식이 서로 다르며, 이는 사용자의 접근성과 재사용성을 떨어트린다. 이로 인해 표준화된 매핑 언어의 필요성이 대두되었으며, W3C에서는 RDB to RDF 모델의 표준 매핑 언어로서 R2RML을 제안하였다. R2RML은 관계형 데이터베이스 스키마 정보만을 RDF로 변환하는 특징을 가진다. 이와 같은 이유로 관계형 데이터베이스의 테이블 명, 컬럼 명 사이의 관계정보에 대한 온톨로지를 추가할 수 없다. 이 논문에서는 이러한 문제를 해결하기 위해 관계형 데이터베이스 구성 요소의 의미 관계를 고려한 RDB to RDF 매핑 시스템을 제안한다. 제안 시스템은 R2RML에서 정의한 관계형 데이터베이스의 스키마 정보에 RDFS 속성 정보를 확장하여 매핑 정보를 생성한다. 이러한 매핑 정보는 관계형 데이터베이스에 저장된 데이터를 RDFS 속성 정보가 포함된 RDF로 변환시킨다. 이 논문에서는 제안 시스템을 자바 기반의 프로토타입으로 구현하며, 비교 평가를 위해 관계형 데이터베이스에 저장된 데이터를 RDF로 변환하는 실험을 수행하고 결과를 D2RQ, RDBToOnto, Morph와 비교한다. 제안 시스템은 다른 연구들에 비해 변환한 온톨로지가 풍부한 의미관계를 표현하며, 데이터 변환 시간에서 가장 우수한 성능을 보인다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(3)
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• pp.39-42
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• 2000

Extensible Markup Language(XML) is fast emerging as the dominant standard for representing data in the World Wide Web. Sophisticated query engines that allow users to effectively tap the data stored in XML documents will be crucial to exploiting the full power of XML. While there has been a great deal of activity recently proposing new semi-structured data models and query languages for this purpose, this paper explores the more conservative approach of using traditional relational database engines for processing XML documents conforming to Document Type Descriptors(DTDs). In this paper, we describe how to generate relational schemas from XML DTDs. The main issues that must be addressed inc]ode (a) dealing with the complexity of DTD element specifications (b) resolving the conflict between the two-level nature of relational schemas (table and attribute) vs. the arbitrary nesting of XML DTD schemas and (c) dealing with set-valued attributes and recursion. We now propose a set of transformations that can be used to "simplify" any arbitrary DTD without undermining the effectiveness of queries over documents conforming to that DTD.

• Journal of the Korean Data and Information Science Society
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• 제17권2호
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• pp.421-436
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• 2006

Huang proposed a grey-based nearest neighbor approach to predict accurately missing attribute value in 2004. Our study proposes which way to decide the number of nearest neighbors using not only the deng's grey relational grade but also the wen's grey relational grade. Besides, our study uses not an arithmetic(unweighted) mean but a weighted one. Also, GRG is used by a weighted value when we impute missing values. There are four different methods - DU, DW, WU, WW. The performance of WW(Wen's GRG & weighted mean) method is the best of any other methods. It had been proven by Huang that his method was much better than mean imputation method and multiple imputation method. The performance of our study is far superior to that of Huang.

• Interdisciplinary Bio Central
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• 제3권3호
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• pp.9.1-9.5
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• 2011

Entity Attribute Value (EAV) is the widely used solution to represent high dimensional and sparse data, but EAV is not search efficient for knowledge extraction. In this paper, we have proposed a search efficient data model: Optimized Entity Attribute Value (OEAV) for physical representation of high dimensional and sparse data as an alternative of widely used EAV. We have implemented both EAV and OEAV models in a data warehousing en-vironment and performed different relational and warehouse queries on both the models. The experimental results show that OEAV is dramatically search efficient and occupy less storage space compared to EAV.

• 한국정보시스템학회:학술대회논문집
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• 한국정보시스템학회 2001년도 추계학술대회 발표논문집:차세대 전상거래 시대의 비즈니스전략
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• pp.64-82
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• 2001

HTML revolutionized the way we specify the appearance of data on the Internet. Today, XML (the eXtensible Markup Language) is changing the way we specify the meaning of data. XML, lets document authors define their own markup tags and attribute names to assign meaning to the data elements in the document. Further, XML elements can be nested and include references to indicate data relationships, as Listing One. Unlike HTML, XML markup tags do not describe how to render the data. Rather, they provide descriptions of data, allowing software to understand the meaning of the data automatically For publishing, instead, XSL, the eXtensible Stylesheet Language as a separate language , is in charge of specifying the presentation of XML documents. The purpose of this study is to discover how to transform your organizations relational data into potential e-commerce, business-to-business, and web application with XML and XSL documents. For this purpose, the literature survey, first of all, was undertaken to understand the basic structures of XML documents. Second, one case implementation was performed to understand how to transform Access 2002 XML Files into HTML with XSLTand VB script. The results come out to be successful, more or less. But the limitations of it still exist. One immediate limitation is that XML documents are essentially tree structure, as dictated by the nesting of elements. However, relational database tables are two dimensional matrix structure. In addition, real-world data often is graph structured-a single data element may be referenced in multiple ways. However, this study is useful for understanding how to convert relational database into XML documents and to publish them using XSL or VB script.

• 한국경영과학회지
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• 제13권1호
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• pp.51-64
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• 1988

A new approach to the logical design of 4NF database shceme, which can be easily automated, is proposed. The main features of the approach are : introduction of a single attribute right hand side, extension of the concept of independent relations, semantic analysis, and adaoption of dependency matrix. The underlying viewpoints of functional relationships of the approach are different from Fagin's in that we distinguish functional and multivalued dependency in terms of cardinality. An algorithm for automatic generation of fourth normal form is presented and implemented.