• Proceedings of the Korea Database Society Conference
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• 1995.12a
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• pp.153-162
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• 1995

Network를 통하여 분산되어 있는 멀티미디어PC들의 사용자간에 개별/공동학습 및 저작을 지원하기 위한 CSCW모형에 대하여 논한다. 이 응용 모형은 사용자나 저작자들이 어떻게 협력할 수 있는지, 다사용자 간의 상호작용을 지원할 수 있는 모드에는 어떤 것이 있는지를 기술한다. 또한 통신과 협력기능을 갖는 하부구조를 기반으로 멀티미디어 인터페이스를 통한 공유작업공간을 구축하고, 헙력하여 복잡한 문제를 해결하는 환경 설계에 대하여 논한다.

• Proceedings of the Korea Database Society Conference
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• 1998.09a
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• pp.475-505
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• 1998

With rapid progresses in information technologies, managing enterprise network resources as a whole becomes more important. Telecommunication Management Network (TMN) has been used to integrate network elements. TMN is complex to develop and manage because it has a centralized management service. Common Object Request Broker Architecture (CORBA) can overcome this complexity by the use of transparent distributed object processing mechanism. Therefore, the main objective of this paper is to integrate TMN service with CORBA. A network management repository is built for this integration. In addition, a prototype that can partially support network management service is implemented to illustrate the usefulness of this repository.

• Journal of KIISE:Databases
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• v.30 no.6
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• pp.629-640
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• 2003

A shared disk (SD) cluster couples multiple nodes for high performance transaction processing, and all the coupled nodes share a common database at the disk level. In the SD cluster, a transaction routing corresponds to select a node for an incoming transaction to be executed. An affinity-based routing can increase local buffer hit ratio of each node by clustering transactions referencing similar data to be executed on the same node. However, the affinity-based routing is very much non-adaptive to the changes in the system load, and thus a specific node will be overloaded if transactions in some class are congested. In this paper, we propose a dynamic transaction routing scheme that can achieve an optimal balance between affinity-based routing and dynamic load balancing of all the nodes in the SD cluster. The proposed scheme is novel in the sense that it can improve the system performance by increasing the local buffer hit ratio and reducing the buffer invalidation overhead.

• Proceedings of the Korea Database Society Conference
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• 2001.06a
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• pp.281-294
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• 2001

HMS(Hallym Mediator System)는 XML을 기본 데이터 모델로 하여 인터넷에 산재하여 있는 분산이질 정보에 대한 통합, 검색기능을 제공하는 미디에이터 시스템이다. 분산이질 정보의 공통 스키마 구조로서 XML DTD를 사용하며, 각종 정보에 대한 가상의 통합 뷰(view) 생성기능을 제공하여 웹 상의 통합된 가상정보 구조를 표현한다. 웹 상의 일반 사용자는 이와 같이 생성된 뷰 DTD를 근거로 분산이질 정보에 대한 구조적, 내용적 질의를 수행할 수 있다. HMS는 가상접근 기법(virtual approach) 기반의 정보검색 시스템으로서, 사용자 질의는 XML 형태의 소스 매핑정보를 이용하여 각 소스에 대한 부질의로 변환되며, 각 소스로부터의 검색결과는 시스템에 의하여 통합되어 XML 문서 형태로 돌아오게 된다. HMS에서 는 DTD 구동형의 비쥬얼 사용자 인터페이스를 제공하여, 관리자와 일반 사용자에게 직관적이고 간편한 가상정보 구축 및 질의검색 환경을 제공한다.

• Journal of Korea Spatial Information System Society
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• v.1 no.2 s.2
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• pp.33-46
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• 1999

In distributed computing platforms like CORBA, wrappers are used to integrate heterogeneous systems or databases. A spatial data provider is one of the wrappers because it provides clients with uniform access interfaces to diverse data sources. The individual implementation of spatial data providers for each of different data sources is not efficient because of redundant coding of the wrapper modules. This paper presents a new architecture of the spatial data provider which consists of two layered objects : independent wrapper components and dependent wrapper components. Independent wrapper components would be reused for implementing a new data provider for a new data source, which dependent wrapper components should be newly coded for every data source. This paper furthermore discussed the issues of implementing the representation of query results in the middleware. There are two methods of keeping query results in the middleware. One is to keep query results as non-CORBA objects and the other is to transform query results into CORBA objects. The evaluation of the above two methods shows that the cost of making CORBA objects is very expensive.

• Journal of KIISE:Databases
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• v.35 no.1
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• pp.84-95
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• 2008

Wireless sensor networks have recently emerged as a platform for several applications. By deploying wireless sensor nodes and constructing a sensor network, we can remotely obtain information about the behavior, conditions, and positions of objects in a region. Since sensor nodes operate on batteries, energy-efficient mechanisms for gathering sensor data are indispensable to prolong the lifetime of a sensor network as long as possible. In this paper, we propose a novel clustering algorithm that distributes the energy consumption of a cluster head. First, we analyze the energy consumption if cluster heads and divide each cluster into a collection layer and a transmission layer according to their roles. Then, we elect a cluster head for each layer to distribute the energy consumption of single cluster head. In order to show the superiority of our clustering algorithm, we compare it with the existing clustering algorithm in terms of the lifetime of the sensor network. As a result, our experimental results show that the proposed clustering algorithm achieves about $10%{\sim}40%$ performance improvements over the existing clustering algorithms.

• Journal of KIISE:Software and Applications
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• v.26 no.6
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• pp.713-723
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• 1999

하나의 클래스를 인터페이스(interface)와 구현부(implementation)로나누어 다루는 '클래스-분리'에 대한 연구는 최근 프로그래밍언어 분야 또는 분산처리 분야를 비롯하여 데이터베이스 분야에서도 그 유용성이 입증되고 있다. 그러나, 데이터베이스를 위한 클래스-분리에 관한 문헌들은 아직까지는 추상적이고 간단한 설명만을 제시하고 있기 때문에, 실제 DBMS(Dabatase Management System)를 구현할 때 참조할 만한 자료가 없는 실정이다. 본 논문은 ODMG-93기반 C++데이타베이스 프로그래밍 언어를 위해 클래스-분리를 지원하는 구체적인 방안을 제시하고, 기존의 타분야에서 사용된 기타방법들과 비교한다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.10a
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• pp.275-278
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• 1996

We propose dynamic file allocation method in distributed database management system with changing access patterns. There are a lot of studies on file allocation problem in D-DBMS, and those studies deal with off-line analysis and optimization. Those works are well for systems with static database access patterns, but are inadequate for systems that have changing access patterns. In these systems, dynamic file allocation along with access pattern is more proper. In advance, Brunstrom et al. studied on this area, but they dealt a extremely simplified model. So, we make more practical models to simulate real system. In these models, many factors that were disregard in the advance study are considered. These models are composed with the non-replication system and the replication system. In addition to, we deal with CPU workload balancing in such system in order to improve performance of systems. Our methodology is very simple and realistic, therefore we think that it will give a lot of improvement in D-DBMS with changing access pattern.

• Annual Conference on Human and Language Technology
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• 1996.10a
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• pp.393-399
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• 1996

자연언어 대화에서 사용자의 정확한 의도(Intention)를 인지함에 있어서 나타나는 문제는, 자연언어 대화체의 생략성이 강한 문장의 불완전성 외에도, 여러 연속되는 대화체 문장에 분산되어 나타나는 사용자의 의도를 정확히 파악하는 것이다. 이러한 불완전한 대화체 문장 속에 산재되어 있는 사용자의 의도를 빠르고 신뢰성 있게 인지하여, 사용자와 시스템간의 원활한 자연언어 대화 상호작용 (Interaction)을 가능하게 하기 위하여 플랜 인지 시스템의 이용은 매우 효과적으로 보인다. 현재까지 개발된 대부분의 플랜 인지시스템들은 사용자의 액션 분석 및 플랜의 인지를 통하여 HCI를 지원하는 측면에 (예: 지능형 도움말) 집중되어 있다. 본 논문은 지역 광고 신문에 실린 매입-매도광고 데이타베이스의 검색을 위한 Natural language dialogue user interface에서 사용자 의도를 인지할 수 있는 플랜 인지 시스템을 기술하고 있다.

• Journal of KIISE:Databases
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• v.31 no.2
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• pp.83-90
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• 2004

In this paper, we study the CCD(Clustering with Circular Distance) and the COD(Clustering with Obstructed Distance) problems to be considered when objects are being clustered in a circularly search space and a search space with the presence of obstacles. We also propose a now clustering algorithm for clustering efficiently objects that the insertion or the deletion is occurring frequently in multi-dimensional search space. The distance function for solving the CCD and COD Problems is defined in the Proposed clustering algorithm. This algorithm is included a clustering method to create clusters that have a high spatial locality by minimum computation time.