• Proceedings of the Korean Operations and Management Science Society Conference
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• 1999.04a
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• pp.381-383
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• 1999

WDM(Wavelength Division Multiplexing) Ring에서 경로과 고정된 파장할당문제는 Circular Arc Graph(CAG)에서의 vertex coloring문제와 동일하다. 본 연구에서는 극대독립집합(Maximal Independent Set)으로 vertex를 cover하는 정수계획법 모형을 제시하고 이를 효율적으로 풀 수 있는 column generation approach와 실험결과를 제시하겠다.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.1
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• pp.35-44
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• 1991

An expert system that diagnoses the malfunction of local area network is developed. The system detects specific devices in the network as the source of thd deta disconnection. These soures are sct to goals in the knowledge base and rules are constructed by uncluding all possible occurrences un thd connection of therminals and host computers. An approach via OR graph is employed for thd systematic rule generation. The system is implemented in a shell and illustrative inference processes are presented.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.893-895
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• 2003

단백질간 구조 비교는 기능적 또는 구조적으로 연관된 단백질을 분류하거나 모티프(motif)를 찾는데 유용하게 사용되고 있다. 여러 가지 단백질간 구조 비교 방법 중에서 단백질 2차구조를 이용하는 방법은 실행속도의 측면에서 장점이 있다. 본 논문에서는 단백질 2차 구조와 그들 사이의 관계를 기반으로 한 단백질 구조 비교에서 사용될 유사성 그래프를 생성하는 방법을 기술하였다. 유사성 그래프는 단백질의 2차구조 사이의 관계를 노드로 하여 생성되는데, 그 시간복잡도가 O(n$^4$)이다. 이에 본 논문에서는 유사성 그래프의 생성을 효율적으로 할 수 있는 알고리즘을 개발하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.352-354
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• 2004

현재의 모델 체커는 모델이 속성을 만족하지 않을 경우 반례를 사용자에게 보여주어서 디버깅을 돕는다. 모델 체커에서 반례는 중요한 장점 중에 하나이지만 대부분의 모델 체커에서 반례로서 하나의 경로만을 보여주게 된다. 하지만 사용자가 원하는 것은 그 이상의 정보를 원할 수 있다. 따라서 반례에서 좀더 많은 정보를 보여줄 필요가 있다. 이런 종류의 연구로서 트리 형식의 반례 생성과 증명 형식의 반례생성이 있었다. 하지만 이 연구들은 시스템이 가질 수 있는 모든 경로를 알아낼 수는 없고 또한 증명 형식의 반례 생성의 경우 상태공간을 다른 형식으로 변경을 해야 한다. 본 논문에서는 반례로서 도달 가능한 모든 경로를 그래프 형식으로 보여줄 수 있는 그래프 형식의 반례를 정의하고 생성방법에 대해서 알아본다

• Annual Conference on Human and Language Technology
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• 2019.10a
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• pp.404-408
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• 2019

비지도 학습 모델인 GAN은 학습 데이터 구축이 어려운 여러 분야에 활용되고 있으며, 알려진 문제점들을 보완하기 위해 다양한 모델 결합 및 변형으로 발전하고 있다. 하지만 문장을 생성하는 GAN은 풀어야 할 문제가 많다. 그중에서도 문제가 되는 것은 완성도가 높은 문장을 생성하는데 어려움이 있다는 것이다. 본 논문에서는 단어 그래프를 구성하여 GAN의 학습에 도움을 주며 완성도가 높은 문장을 생성하는 방법을 제안한다.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.3
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• pp.17-33
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• 2000

We consider the Steiner tree packing problem. For a given undirected graph G =(V, E) with positive integer capacities and non-negative weights on its edges, and a list of node sets(nets), the problem is to find a connection of nets which satisfies the edge capacity limits and minimizes the total weights. We focus on the switchbox routing problem in knock-knee model and formulate this problem as an integer programming using Steiner tree variables. The model contains exponential number of variables, but the problem can be solved using a polynomial time column generation procedure. We test the algorithm on some standard test instances and compare the performances with the results using cutting plane approach. Computational results show that our algorithm is competitive to the cutting plane algorithm presented by Grotschel et al. and can be used to solve practically sized problems.

• Management Science and Financial Engineering
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• v.9 no.1
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• pp.11-27
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• 2003

In this study, we propose a mathematical model based on the graph theory for the wavelength assignment problem arising in the design of SDH (Synchronous Digital Hierarchy) over WDM (Wavelength Division Multiplexing) ring networks. We propose a branch- and -price algorithm to solve the suggested models effectively within reasonable time in realistic SDH over WDM ring networks. By exploiting the structure of ring networks, we developed a polynomial time algorithm for efficient column generation and a branching rule that conserves the structure of column generation. In a computer simulation study, the suggested approach can find the optimal solutions within reasonable time and show better performance than the existing heuristics.

• Journal of KIISE:Software and Applications
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• v.34 no.4
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• pp.368-376
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• 2007

How to represent the search space is as important as which search algorithm to use for finding natural-looking paths for moving NPC (non-player character) in computer games. Recently, various state space representation methods which have been developed for computer games are being used while A* algorithm dominates as the preferred search algorithm. These representation methods show some drawbacks such as the size of state space is too large, there is no guarantee for optimality, the path found is not natural-looking, and the generation of nodes and links is not automatic by depending on a level designer. In this paper the requirements for natural-looking paths are introduced and to find paths satisfying these requirements, the use of the generalized visibility graphs which is the extended version of the visibility graph in Robotics is proposed.

• Journal of Korea Multimedia Society
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• v.6 no.6
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• pp.1088-1099
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• 2003

The syntax-directed translation using semantic actions is frequently used in construction of compiler for text programming languages. it is very useful for the language designers to develop compiler back-end using a syntax structure of a source programming language. Due to the lack of the integrated representation method for a parse tree node and modeling method of syntax structures, it is very hard to construct compiler using syntax-directed translation in visual languages. In this Paper, we propose a visual language compiler generation method for constructing a visual languages compiler automatically, using syntax-directed translation. Our method uses the Picture Layout Grammar as a underlying grammar formalism. This grammar allows our approach to generate parser efficiently u sing And-Or-Waiting Graph and encapsulating syntax definition as one unit. Unlike other systems, we suggest separating the specification and the generation of semantic actions. Because of this, it provides a very efficient method for modification.

• Journal of Korea Multimedia Society
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• v.11 no.9
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• pp.1310-1323
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• 2008

Recently, many studies on automated generation of composite Web services have been done. Most of these works compose Web services by chaining their inputs and outputs, but do not consider the functional semantics. Therefore, they may construct unsatisfied composite services against users' intention. Futhermore, they have high time-complexity since every possible combinations of available services should be considered. To resolve these problems, this paper proposes a sophisticated composition method that explicitly specifies and uses the functional semantics of Web services. Specifically, A graph model is constructed to represent the functional semantics of Web services as well as the dependency among inputs and outputs. On the graph, we search core services which provide the requested function ality and additional services which transform between I/O types of the user request and the core services. Then, composite services are built from combinations of the discovered services. The proposed method improves the semantic correctness of composite services by the functional semantics of Web services, and reduces the time complexity by combinations of functionally related services.