• Journal of KIISE:Software and Applications
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• v.36 no.2
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• pp.144-152
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• 2009

To provide intelligent service in mobile environment, it needs to estimate user's intention or requirement, through analyzing context information of end-users such as preference or behavior patterns. In this paper, we infer context information from uncertain log stored in mobile device. And we propose the inference method of end-user's behavior to match context information with service, and the proposed method is based on context-tree. We adopt bayesian probabilistic method to infer uncertain context information effectively, and the context-tree is constructed to utilize non-numerical context which is hard to handled with mathematical method. And we verify utility of proposed method by appling the method to intelligent phone book service.

• The KIPS Transactions:PartD
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• v.10D no.7
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• pp.1077-1088
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• 2003

To increase the retrieval performance in spatial database systems, it is required to develop spatial indexing methods considered the spatial locality. The spatial locality is related to the location property of objects. The previous spatial indexing methods are not considered the circular location property that objects will be taken. In this paper, we propose a dynamic spatial index structure called $Cr^*$-tree, and evaluate the performance of the proposed index structure. This is a new spatial index structure considered the circular location property of objects in which a search space is constructed with the circular and linear domains. By the simulation results, the $Cr^*$-tree shows that the number of disk across is low and the bucket utilization is high regardless of object distribution and bucket capacity.

• Journal of Internet Computing and Services
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• v.6 no.5
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• pp.1-9
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• 2005

In a role based access control through attribute certificate, the use of role assignment certificates and role specification certificates can reduce management cost and the overhead incurred by changing roles, Highly distributed computing environments such as ubiquitous computing environments not having global or broad control. need another attribute certificate management technique, Actually just having role specification certificate separately reduce management cost, But for better performance we structure role specification, We group roles and make the role group relation tree, It results secure and efficient role renewing and distribution, For scalable role specification certificate distribution, the multicasting of packets is used, We take into account the packet lass and quantify performance enhancements of structuring role specification certificates.

• Journal of Creative Information Culture
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• v.5 no.3
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• pp.345-353
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• 2019

Several studies have been proposed to improve storage space efficiency by expressing binary trie data structure as a linear binary bit string. Compact binary tree approach generated using one binary trie increases the key search time significantly as the binary bit string becomes very long as the size of the input key set increases. In order to reduce the key search range, a hierarchical compact binary tree technique that hierarchically expresses several small binary compact trees has been proposed. The search time increases proportionally with the number and length of binary bit streams. In this paper, we generate several binary compact trees represented by full binary tries hierarchically. The search performance is improved by allowing a path for the binary bit string corresponding to the search range to be determined through simple numeric conversion. Through the performance evaluation using the worst time and space complexity calculation, the proposed method showed the highest performance for retrieval and key insertion or deletion. In terms of space usage, the proposed method requires about 67% ~ 68% of space compared to the existing methods, showing the best space efficiency.

• Journal of KIISE:Software and Applications
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• v.28 no.7
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• pp.524-536
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• 2001

본 논문에서는 다수의 페이지로 구성된 복잡한 구조의 문서로부터 SGML/XML에 기반한 전자 문서를 생성하기 위한 구문론적인 구조분석 방법을 제안한다. 특히 제안된 파싱 기법은 텍스트 라인을 기본 단위로 하는 기존 연구보다 논리적인 계층 구조를 보다 정확하고 빠르게 생성하기 위하여 텍스터 영역의 계층적인 트리 구조를 입력으로 받아들인다. 또한 문서 유형의 논리적인 구조 정보와 기하적인 특성을 효과적으로 기술할 수 있는 문서모델을 정의하고, 이의 자동 생성과 점증적인 학습 방법을 제안한다. 제안된 방법의 성능을 평가하기 위하여 과학 기술 논문으로부터 스캐닝한 372개의 논문 연상으로 실험한 결과, 제안된 방법은 기존 연구와 달리 다수의 문서 영상으로 구성된 문서에 대하여 논리적인 구조분석과 문서 모델의 자동 생성을 효율적으로 지원하였다. 특히 제안된 방법은 논리적인 구조분석의 최종 결과로서 SGML/XML 문서를 생성하기 때문에 문서의 재 사용성과 호환성을 높인다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.175-177
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• 2000

본 논문에서는 다수의 페이지로 구성된 복잡한 구조의 문서로부터 SGML/XML에 기반한 전자 문서를 생성하기 위한 구문론적인 구조분석 방법을 제안한다. 제안된 방법은 구조분석의 정확성과 처리속도의 향상을 위하여 텍스트 영역의 계층적인 트리를 파싱하여 논리적인 계층 구조를 추출한다. 또한 본 논문은 문서 유형의 논리적인 구조 정보와 기하적인 특성을 효과적으로 기술할 수 있는 문서 모델을 정의한다. 제안된 방법의 성능을 평가하기 위하여 IEEE Transactions on Pattern Analysis and Machine Intelligence로부터 스캐닝한 372개의 논문 영상으로 실험한 결과, 제안된 방법은 기존 연구와 달리 다수의 문서 영상으로 구성된 문서에 대하여 논리적인 구조분석을 효율적으로 지원하였다. 특히 제안된 방법은 논리적인 구조분석의 최종 결과로서 SGML/XML 문서를 생성하기 때문에 문서의 재사용성과 호환성을 높인다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.215-223
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• 2010

New information technologies make it easy to access and acquire information in various ways. However, It also enable powerful and various threat to system security. The prominent database technology challenging these threats is access control. Currently, to keep pace with the new paradigms, new extended access control methods are challenged. We study access control with uncertain context. With respect to access control, it is possible that there is a discrepancy between the syntactic phrase in security policies and that in queries, called semantic gap problem. In our semantic access control, we extract semantic implications from context tree and introduce the measure factor to calculate the degree of the discrepancy, which is used to control the exceed privileges.

• Annual Conference of KIPS
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• 2005.05a
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• pp.1205-1208
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• 2005

구조적 문서에 대한 접근제어를 위해서 필수적으로 보안 계층에 대한 문제가 고려되어야 한다. 본 논문에서는 사용자가 가지는 보안계층, 즉 사용자 역할 계층에서의 접근제어 문제를 해결하기 위한 효율적인 키 관리 방법을 제안한다. 본 논문에서 제안된 방법은 OWHF(One-way Hash Function)를 이용하여 효과적으로 키를 할당하고 유도한다. 제안된 방법을 역할 계층 트리에서 역할의 추가와 삭제, 역할 계층의 갱신과 같은 동적 접근제어 문제에 적용하고 이를 분석한다.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2
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• pp.347-354
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• 2000

This paper presents the efficient mechanisms for concurrency control and writing authority control in collaborative writing system are represented by the tree structures which consist of the logical objects and the content objects connected to the terminal objects of trees. For concurrency control, we adopted the approach to extend the multiple-granularity-locking-scheme. This scheme allows us to lock any objects at each level of the hierarchy. We also defined the locking compatibility table by analysing the operations applicable to any objects at each level of the hierarchy. We finally suggest the extended-multiple-granularity-locking mechanism which uses the locking compatibilility table for deciding to lock an object. This scheme gives the benefit to maximize the possibility of concurrent accessing to the shared objects. In addition, we suggest a mechanism for writing authority control which prohibits the Non-Group users from modifying the shared objects based on the concept of Group/Non-Group The proposed mechanism allows us to protect copyright very reasonably.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.268-278
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• 2004

In this paper, we describe our experience in the design and implementation of the SMART file system to handle multimedia workload. Our work has three design objectives: (ⅰ) efficient support for sequential workload, (ⅱ) avoiding disk fragmentation, (ⅲ) logical unit based file access. To achieve these three objectives, we develop a file system where a file consists of linked list of Data Unit Group. Instead of tree like structure of the legacy Unix file system, we use single level file structure. Our file system can also access the file based upon the logical unit which can be video frame or audio samples. Data Unit Group is a group of logical data units which is allocated continuous disk blocks. At the beginning of each Data Unit Group, there exists an index array. Each index points to the beginning of logical data units, e.g. frames in the Data Unit Group. This index array enables the random access and sequencial access of semantic data units. SMART file system is elaborately tailored to effectively support multimedia workload. We perform physical experiments and compare the performance of SMART file system with EXT2 file system and SGI XFS file system. In this experiment, SMART file system exhibits superior performance under streaming workload.