• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.4
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• pp.303-308
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• 2004

Natural language query is the best user interface for the users of information retrieval systems. This paper Proposes a retrieval system with expanded keyword from syntactically-analyzed structures of user's natural language query based on natural language processing technique. Through the steps combining or splitting the compound nouns based on syntactic tree traversal, and expanding the other-formed or shorten-formed keyword into multiple keyword, the system performance was enhanced up to 11.3% precision and 4.7% correctness.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11c
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• pp.1583-1586
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• 2003

소프트웨어 개발에서 프로그램의 검증과 확인을 위한 기본적인 방법중에 하나로 디버깅이 있다. 디버깅의 대표적인 기술중에 하나인 알고리즈믹 디버깅에서는 실행트리라는 구조를 사용한다. 실행 트리란 프로그램을 실행하면서 프로그램내의 모든 함수의 호출 관계를 나타낸 트리 구조이다. 본 논문에서는 실행트리에서 반복문안에 함수 호출이 있을 경우에 나타나는 문제점을 지적한다. 실행트리의 문제점은 반복문안에 함수 호출이 있을 경우 실행트리의 노드가 같은 내용이 반복해서 나타난다. 이와 같은 경우에 함수 호출에 대한 반복된 사용자의 응답을 줄일 수 있는 방법을 본 논문에서 제시한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05c
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• pp.540-545
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• 2002

3D 그래픽스는 이제 전문가들만의 전유물이 아니다. 하드웨어 기술의 비약적인 발전으로 누구나 저렴한 가격으로 불과 몇 년전의 워크스테이션급 이상의 3D 그래픽스 환경을 갖출 수 있게 되었다. 그러나 3D 그래픽스 환경을 조작하기에 적합한 특수 장비는 여전히 일반 소비자가 사용 할 수 없을 정도의 고가이며 대중화는 요원한 실정이다. 따라서 일반적인 2D 기반의 입력장치를 활용한 데스크탑 가상현실에서의 효과적인 인터페이스의 연구가 필요하다. 사용자가 최초로 가상 환경내의 객체를 조작하기 위해서 취하는 행동은 선택이다. 그러나 일반적인 데스크탑 환경에서 3D 객체의 선택은 정확성이 떨어지며 오류의 정정도 번거롭다. 본 논문에서는 일반적인 마우스를 가지고 3D 가상환경의 객체를 정확하게 선택할 수 있도록 돕는 인터페이스를 제안한다. 시스템은 사용자가 선택한 객체와 관련된 선택 가능한 후보 객체들로 구성된 선택 트리를 제시하며, 선택 트리 내에서의 순회를 통해 사용자가 정확한 선택과 오류 정정을 하도록 돕는다.

• Journal of Korean Society for Quality Management
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• v.26 no.1
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• pp.192-200
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• 1998

The quickest path problem is one of the important things for quality of services in communication networks. It is to find a path to send a given amount of data from the source to the sink with minimum transmission time, where the transmission time is dependent on both the capacities and the traversal times of the arcs in the network. This is found under the networks that the capacity and the lead time of each ring are predetermined. It is general to solve the quickest path problem using shortest path algorithms. The relevant algorithms proposed till now are based on the capacity of rings in distributed environments. When the configuration of networks is changed, there can be two a, pp.oaches to find the quickest paths. The one is to find new quickest paths, and the other is to update the current quickest paths. As one of the algorithms for the latter, the distributed quickest path update algorithm was proposed. This paper aims to propose the distributed algorithm a, pp.icable to find the quickest path, when the configuration of networks is changed, using the quickest path tree update altorithm, and to verify its possibility of a, pp.ication by analyzing the transmission amount of data from one node to another from the theoretical point of view.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.4
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• pp.158-167
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• 2007

Indirect illumination plays an important role for realistic image synthesis. We present a novel realtime indirect illumination rendering technique using image pyramids. Hundreds of thousands of indirect point light sources are stored into images, and then they hierarchically clustered into quad-tree image pyramids. We also introduce a GPU based top-down and breadth-first traversal of the quad-trees to approximate the illumination with clusters (set of lights). All steps entirely run on the GPU in real-time. Result images demonstrate that our method represents diffuse interreflection, especially a color bleeding effect well. We achieved interactive frame rates of tens to hundreads, without any preprocessing. We can avoid artifacts caused by sampling, and our method is seven times faster than a recently proposed sampling based method.

• Journal of Korea Spatial Information System Society
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• v.11 no.1
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• pp.127-136
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• 2009

This paper proposes an on-line mining algorithm of moving trajectory patterns in RFID data streams considering changing characteristics over time and constraints of single-pass data scan. Since RFID, sensor, and mobile network technology have been rapidly developed, many researchers have been recently focused on the study of real-time data gathering from real-world and mining the useful patterns from them. Previous researches for sequential patterns or moving trajectory patterns based on stream data have an extremely time-consum ing problem because of multi-pass database scan and tree traversal, and they also did not consider the time-changing characteristics of stream data. The proposed method preserves the sequential strength of 2-lengths frequent patterns in binary relationship table using the time-evolving graph to exactly reflect changes of RFID data stream from time to time. In addition, in order to solve the problem of the repetitive data scans, the proposed algorithm infers candidate k-lengths moving trajectory patterns beforehand at a time point t, and then extracts the patterns after screening the candidate patterns by only one-pass at a time point t+1. Through the experiment, the proposed method shows the superior performance in respect of time and space complexity than the Apriori-like method according as the reduction ratio of candidate sets is about 7 percent.