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문개현,허순영 한국경영과학회 2002 한국경영과학회 학술대회논문집 Vol.2002-A No.-
To provide approximate neighborhood answers in addition to exact answers, this paper proposes a cooperative query answering approach that relaxes query conditions by utilizing similarity relationships between data values. The proposed fuzzy abstraction hierarchy (FAH) that combines the abstraction hierarchy and the semantic distance approaches represents similarity relationship based on the integrated notion of data abstraction and fuzzy relations. As a result, FAH acquires richer semantic knowledge of an underlying database and embraces the advantages of existing data abstraction and semantic distance approaches. Also, to be tolerant of<br/> incorrect input for queries, FAH adopts thesaurus for synonym information about database token. Based on FAH, we develop query relaxation operators such as query generalization, approximation, and specialization of a value Compared with existing approaches, FAH supports more effective information retrieval by allowing conceptually abstracted queries and providing query result sets ranked according to the similarity strength (i.e., fitness score) Furthermore, compared with semantic distance approach, FAH considerably reduces maintenance costs by decreasing the number of similarity strength to be assigned.
데이터 추상화와 퍼지 관계를 이용한 근사적 질의응답에 관한 연구
허순영,문개현 한국경영과학회 2000 한국경영과학회 학술대회논문집 Vol.- No.1
본 논문은 데이터베이스에 존재하는 데이터 값들 사이의 유사성에 관한 지식을 이용하여 사용자가 요구한 정확한 답뿐 아니라 그와 유사한 답까지 제공해 줄 수 있는 근사적 질의처리 기법을 제시한다. 이를 위하여, 계량적인 방법에 해당하는 퍼지 관계와 비계량적인 방법에 해당하는 데이터 추상화를 하나로 통합한 유사성 표현 프레임윅을 제시하고 그를 이용한 지식 베이스를 설계한다.
Intelligent Query Processing Using a Meta-Database KaDB
허순영,문개현 한국데이타베이스학회 1999 공동학술대회 Vol.1 No.1
Query language has been widely used as a convenient tool to obtain information from a database. However, users demand more intelligent query processing systems that can understand the intent of an imprecise query and provide additional useful information as well as exact answers. This paper introduces a meta-database and presents a query processing mechanism that supports a variety of intelligent queries in a consistent and integrated way. The meta-database extracts data abstraction knowledge from an underlying database on the basis of a multilevel knowledge representation framework KAH. In cooperation with the underlying database, the meta-database supports four types of intelligent queries that provide approximately or conceptually equal answers as well as exact ones.
허순영,문개현 한국경영과학회 1998 韓國經營科學會誌 Vol.23 No.2
Cooperative query answering is a research effort to develop a fault-tolerant and intelligent database system using the semantic knowledge base constructed from the underlying database. Such knowledge base has two aspects of usage. One is supporting the cooperative query answering process for providing both an exact answer and neighborhood information relevant to a query. The other is supporting ongoing maintenance of the knowledge base for accommodating the changes in the knowledge content and database usage purpose. Existing studies have mostly focused on the cooperative query answering process but paid little attention on the dynamic knowledge base maintenance. This paper proposes a multi-level knowledge representation framework called Knowledge Abstraction Hierarchy (KAH) that can not only support cooperative query answering but also permit dynamic knowledge maintenance. The KAH consists of two types of knowledge abstraction hierarchies. The value abstraction hierarchy is constructed by abstract values that are hierarchically derived from specific data values in the underlying database on the basis of generalization and specialization relationships. The domain abstraction hierarchy is built on the various domains of the data values and incorporates the classification relationship between super-domains and sub-domains. On the basis of the KAG, a knowledge abstraction database is constructed on the relational data model and accommodates diverse knowledge maintenance needs and flexibly facilitates cooperative query answering. In terms of the knowledge maintenance, database operations are discussed for the cases where either the internal contents for a given KAH change or the structures of the KAH itself change. In terms of cooperative query answering.