• Asia pacific journal of information systems
• /
• 제8권1호
• /
• pp.43-64
• /
• 1998

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 to 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, On the basis of the KAH, 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, four types of vague queries are discussed, including approximate selection, approximate join, conceptual selection, and conceptual join. A prototype system has been implemented at KAIST and is being tested with a personnel database system to demonstrate the usefulness and practicality of the knowledge abstraction database in ordinary database application systems.

• 한국정보시스템학회지:정보시스템연구
• /
• 제8권1호
• /
• pp.27-44
• /
• 1999

Case-Based Reasoning(CBR) offers a new approach for developing knowledge based systems. CBR has several research issues which can be divided into two categories : (1) static issues and (2) dynamic issues. The static issues are related to case representation scheme and case data model, that is, focus on casebase which is a repository of cases. The dynamic issues, on the other hand, are related to case retrieval procedure and problem solving process, i.e. case adaptation phase. This research is forcused on retrieval procedure Traditional query processing accepts precisely specified queries and only provides exact answers, thus requiring users to fully understand the problem domain and the casebase schema, but returning limited or even null information if the exact answer is not available. To remedy such a restriction, extending the classical notion of query answering to approximate query answering(AQA) has been explored. AQA can be achieved by neighborhood query answering or associative query answering. In this paper, neighborhood query answering technique is used for AQA. To reinforce the CBR process, a new retrieval procedure(cooperative CBR) using neighborhood query answering is proposed. An neighborhood query answering relaxes a query scope to enlarge the search range, or relaxes an answer scope to include additional information. Computer Aided Process Planning(CAPP) is selected as cooperative CBR application domain for test. CAPP is an essential key for achieving CIM. It is the bridge between CAD and CAM and translates the design information into manufacturing instructions. As a result of the test, it is approved that the problem solving ability of cooperative CBR is improved by relaxation technique.

• 한국경영과학회지
• /
• 제23권2호
• /
• pp.131-156
• /
• 1998

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 KAH, 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, database operations are discussed for both the generalization and specialization Processes, and the conceptual query handling. A prototype system has been implemented at KAIST that demonstrates the usefulness of KAH in ordinary database application systems.

• 한국지능정보시스템학회:학술대회논문집
• /
• 한국지능정보시스템학회 2006년도 춘계학술대회
• /
• pp.354-360
• /
• 2006

The purpose of this paper is to propose a securely personalized context-aware cooperative query that supports a multi-level data abstraction hierarchy and conceptual distance metric among data values, while considering privacy concerns around user context awareness. The conceptual distance expresses a semantic similarity among data values with a quantitative measure, and thus the conceptual distance enables query results to be ranked. To show the feasibility of the methodology proposed in this paper we have implemented a prototype system in the area of site search in a large-scale shopping mall.

• 한국컴퓨터정보학회논문지
• /
• 제11권3호
• /
• pp.87-96
• /
• 2006

데이터베이스 시스템에서 협력적 질의응답이란 질의 내용과 정확히 일치하는 자료뿐만 아니라 좀 더 넓은 인근 범위의 자료 또는 근사적인 자료를 검색해 주는 것을 말한다. 협력적 질의응답은 질의 분석, 질의 유연화, 유연화된 질의에 따른 근사적 자료 제공의 세 단계로 이루어져 있다. 질의 유연화를 수행하기 위해 의미적 관계를 표현하는 지식추상화 방법과 자료 사이의 정량적인 유사도를 거리로 표현하는 방법들이 지식표현 방법으로 사용된다. 본 논문에서는 보다 효과적으로 질의 유연화 단계를 지원하기 위해, 다단계 데이터 추상화 계층과 거리 척도를 지원하는 계량화된 지식추상화 계층(MKAH: Metricized Knowledge Abstraction Hierarchy)을 제안한다. MKAH는 카테고리화 될 수 있는 자료에 대해 질의 유연화를 효과적으로 지원하며 두 값 사이의 정량적인 의미상의 유사도를 제공하여, 질의 결과에 순위가 매겨질 수 있도록 한다. MKAH의 실용성과 효율성을 검증하기 위하여 경력직 검색 분야에 대한 원형 시스템을 구현해보았다. 다양한 실험을 통하여 MKAH가 풍부한 의미 표현이 가능하면서 질적으로도 높은 거리 척도를 제공해 준다는 것을 보였다. 그 결과 MKAH를 채택하는 도메인은 다른 정량적인 숫자 도메인과 호환될 수 있다는 점과, 큰 규모의 시스템을 만드는 데에도 장점이 있음을 확인하였다.

• 한국정보처리학회논문지
• /
• 제7권1호
• /
• pp.88-98
• /
• 2000

협력적 질의 응답은 질의와 데이터에 관한 지식을 이용해서 초기의 질의에 적절한 인접한 정보나 연관된 정보를 제공한다. 본 논문에서는 제시된 질의에 대한 정확한 검색 결과를 보여주지 못하는 경우에 협력적 질의 응답을 지원하기 위하여 지능적인 질의 응답 시스템을 제안한다. 본 논문에서 제안한 지능적인 질의 응답 시스템은 하이브리드 지식베이스(Hybrid Knowledge Base)를 이용하여 질의 완화 과정을 수행한다. 질의 완화에 사용되는 하이브리드 지식베이스는 구조적인 접근을 위하여 시멘틱 리스트와 규칙 기반의 지식베이스로 구성된다. 또한, 본 논문은 하이브리드 지식베이스를 기반으로 초기의 질의어를 이용하여 질의 재형성을 하기 위하여 질의 완화 알고리즘을 제안한다.

• 지능정보연구
• /
• 제12권4호
• /
• pp.61-72
• /
• 2006

유비쿼터스 서비스가 여러 분야에서 실용화 단계에 와 있다. 특히 u-쇼핑 분야에서는 사용자의 상황에 맞게 상품 혹은 상점을 유연하게 추천해 주는 개인화된 추천이 필요하다. 그러나 현재의 협력적 질의나 상황인식적 검색은 각각 동적 상황과 모호한 검색을 처리하지 못한다는 한계가 있다. 따라서 본 연구의 목적은 이 두 가지 중요한 문제를 해결하기 위하여 개인화된 상황인식적이고 협동적인 검색방법을 상황적MKAH를 유도방법으로 제안하는 것이다. 본 연구의 가능성을 보이기 위해 CACO라고 하는 프로토타입 시스템을 구현하였으며 국내의 한 대규모 쇼핑몰 도메인에 맞게 적용하였다.

• 한국경영과학회:학술대회논문집
• /
• 대한산업공학회/한국경영과학회 1995년도 춘계공동학술대회논문집; 전남대학교; 28-29 Apr. 1995
• /
• pp.990-990
• /
• 1995

• 한국경영과학회지
• /
• 제24권1호
• /
• pp.99-117
• /
• 1999

Since query language is used as a handy tool to obtain information from a database, a more intelligent query answering system is needed to provide user-friendly and fault-tolerant human-machine Interface. Frequently, database users prefer less rigid querying structure, one which allows for vagueness in composing queries, and want the system to understand the intent behind a query. When there is no matching data available, users would rather receive approximate answers than a null information response. This paper presents a knowledge abstraction database that facilitates the development of such a fault-tolerant and intelligent database system. The proposed knowledge abstraction database adepts a multilevel knowledge representation scheme called the knowledge abstraction hierarchy(KAH), extracts semantic data relationships from the underlying database, and provides query transformation mechanisms using query generalization and specialization steps. In cooperation with the underlying database, the knowledge abstraction database accepts vague queries and allows users to pose approximate queries as well as conceptually abstract queries. Specifically. four types of vague queries are discussed, including approximate selection, approximate join, conceptual selection, and conceptual Join. A prototype system has been implemented at KAIST and is being tested with a personnel database system to demonstrate the usefulness and practicality of the knowledge abstraction database in ordinary database application systems.

• Journal of Ubiquitous Convergence Technology
• /
• 제2권1호
• /
• pp.1-11
• /
• 2008

An effective solution to the problems caused by the explosive growth of World Wide Web is a web caching that employing an additional server, called proxy cache, between the clients and main server for caching the popular web objects near the clients. However, a single proxy cache can easily become the bottleneck. Deploying groups of cooperative caches provides scalability and robustness by eliminating the limitations caused by a single proxy cache. Two common architectures to implement the cooperative caching are hierarchical and distributed caching systems. Unfortunately, both architectures suffer from performance limitations. We propose an efficient hybrid caching architecture eliminating these limitations by using both the hierarchical and same level caches. Our performance evaluation with our investigated simulator shows that the proposed architecture offers the best of both existing architectures in terms of cache hit rate, the number of query messages from clients, and response time.