• Title/Summary/Keyword: 그래프분할문제

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A Study on Graph-based Topic Extraction from Microblogs (마이크로블로그를 통한 그래프 기반의 토픽 추출에 관한 연구)

  • Choi, Don-Jung;Lee, Sung-Woo;Kim, Jae-Kwang;Lee, Jee-Hyong
    • Journal of the Korean Institute of Intelligent Systems
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    • v.21 no.5
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    • pp.564-568
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    • 2011
  • Microblogs became popular information delivery ways due to the spread of smart phones. They have the characteristic of reflecting the interests of users more quickly than other medium. Particularly, in case of the subject which attracts many users, microblogs can supply rich information originated from various information sources. Nevertheless, it has been considered as a hard problem to obtain useful information from microblogs because too much noises are in them. So far, various methods are proposed to extract and track some subjects from particular documents, yet these methods do not work effectively in case of microblogs which consist of short phrases. In this paper, we propose a graph-based topic extraction and partitioning method to understand interests of users about a certain keyword. The proposed method contains the process of generating a keyword graph using the co-occurrences of terms in the microblogs, and the process of splitting the graph by using a network partitioning method. When we applied the proposed method on some keywords. our method shows good performance for finding a topic about the keyword and partitioning the topic into sub-topics.

A Method for Time Segment based Activity Pattern Graph Modeling (시간 세그먼트 기반 행위 패턴 그래프 모델링 기법)

  • Park, Ki-Sung;Han, Yong-Koo;Kim, Jin-Seung;Lee, Young-Koo
    • Proceedings of the Korean Information Science Society Conference
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    • 2012.06c
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    • pp.183-185
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    • 2012
  • 행위 DB로부터 행위패턴 분석 및 마이닝을 위해서는 정교한 행위패턴 모델링 기술이 수반되어야 한다. 기존의 그래프기반 행위 패턴 모델링 방법은 하루 행위 시퀀스들의 동일한 행위 시퀀스 세그먼트를 찾아 하나의 행위 시퀀스로 결합시켜 행위 그래프를 생성하였다. 이 방법은 서로 다른 시간에 발생한 행위 시퀀스 세그먼트들이 하나의 행위 시퀀스로 결합되는 문제가 발생한다. 본 논문에서는 하루의 행위 시퀀스를 시간 세그먼트 단위로 분할하고, 각 시간 세그먼트별로 행위 그래프를 생성하여 정교한 행위 그래프 모델을 수립하는 방법을 제안한다. 그래프 마이닝 기법들을 활용한 실험을 통하여 제안하는 행위패턴 모델링 기법이 기존의 행위 그래프 모델 기법보다 더 유용함을 보인다.

Minimization of Communication Cost using Repeated Task Partition for Hypercube Multiprocessors (하이퍼큐브 다중컴퓨터에서 반복 타스크 분할에 의한 통신 비용 최소화)

  • Kim, Joo-Man;Yoon, Suk-Han;Lee, Cheol-Hoon
    • The Transactions of the Korea Information Processing Society
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    • v.5 no.11
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    • pp.2823-2834
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    • 1998
  • This paper deals with the problem of one-to-one mapping of $2^n$ task modules of a parallel program to an n-dimensional hypercube multicomputer so as to minimize to total communication cost during the execution of the task. The problem of finding an optimal mapping has been proven to be NP-complete. We first propose a graph modification technique which transfers the mapping problem in a hypercube multicomputer into the problem of finding a set of maximum cutsets on a given task graph. Using the graph modification technique, we then propose a repeated mapping scheme which efficiently finds a one-to-one mapping of task modules to a hypercube multicomputer by repeatedly applying an existing bipartitioning algorithm on the modified graph. The repeated mapping scheme is shown to be highly effective on a number of test task graphs, it increasingly outperforms the greedy and recursive mapping algorithms as the number of processors increase. The proposed algorithm is shown to be very effective for regular graph, such as hypercube-isomorphic or 'almost' isomorphic graphs and meshes; it finds optimal mapping on almost all the regular task graphs considered.

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Estimation of the Medium Transmission Using Graph-based Image Segmentation and Visibility Restoration (그래프 기반 영역 분할 방법을 이용한 매체 전달량 계산과 가시성 복원)

  • Kim, Sang-Kyoon;Park, Jong-Hyun;Park, Soon-Young
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.4
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    • pp.163-170
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    • 2013
  • In general, images of outdoor scenes often contain degradation due to dust, water drop, haze, fog, smoke and so on, as a result they cause the contrast reduction and color fading. Haze removal is not easier problem due to the inherent ambiguity between the haze and the underlying scene. So, we propose a novel method to solve single scene dehazing problem using the region segmentation based on graph algorithm that has used a gradient value as a cost function. We segment the scene into different regions according to depth-related information and then estimate the global atmospheric light. The medium transmission can be directly estimated by the threshold function of graph-based segmentation algorithm. After estimating the medium transmission, we can restore the haze-free scene. We evaluated the degree of the visibility restoration between the proposed method and the existing methods by calculating the gradient of the edge between the restored scene and the original scene. Results on a variety of outdoor haze scene demonstrated the powerful haze removal and enhanced image quality of the proposed method.

Effective Information Extraction Wrapper Generation and Maintenance by Using a Block-Based Graph Model (블록 단위 그래프 모델을 통한 효율적인 정보 추출 Wrapper 생성과 유지 관리)

  • Park, Ju-Young;Yang, Jae-Young;Choi, Joong-Min
    • Proceedings of the Korean Information Science Society Conference
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    • 2007.10c
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    • pp.322-327
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    • 2007
  • 기존의 정보 추출에서는 웹 문서의 구조가 변경되었을 때 Wrapper가 원하는 정보를 추출할 수 없었다. 또한 웹 문서의 구조가 바뀌는 경우 동일한 정보를 Wrapping함에도 불구하고 사용자는 정보를 추출 할 수 없었던 이유를 찾지 못하는 경우가 대부분이었다. 이 문제를 해결하기 위해 본 논문에서는 Web 페이지를 시각적 블록 단위로 잘라 인접한 블록들을 통해 그래프를 형성하여 웹 문서의 구조가 일부 변경되어도 기존의 Wrapper를 통해 정보를 추출할 수 있도록 보다 효율적으로 Wrapper를 생성하고 유지관리 하는 방법을 제안한다. 또한 웹 문서를 블록 단위로 분할하여 그래프를 생성함으로써 블록 내부에 추출하고자 하는 정보에 대한 규칙이 좀 더 유연하게 표현 될 수 있으며 문서의 구조가 아닌 추출하고자 하는 정보를 중심으로 규칙을 생성함으로써 그래프의 구조뿐 아니라 그래프를 구성하고 있는 블록 내부의 구조가 일부 변하더라도 기존의 규칙을 이용하여 정보를 추출할 수 있도록 하였다.

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The Graph Partition Problem (그래프분할문제)

  • 명영수
    • Journal of the Korean Operations Research and Management Science Society
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    • v.28 no.4
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    • pp.131-143
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    • 2003
  • In this paper, we present a survey about the various graph partition problems including the clustering problem, the k-cut problem, the multiterminal cut problem, the multicut problem, the sparsest cut problem, the network attack problem, the network disconnection problem. We compare those problems focusing on the problem characteristics such as the objective function and the conditions that the partitioned clusters should satisfy. We also introduce the mathematical programming formulations, and the solution approaches developed for the problems.

An Efficient Algorithm for Balancing the Load of ORB Bridges (ORB 브리지의 부하 균등을 위한 효율적인 알고리즘)

  • 김영균;김경하;김영학;오길호
    • Proceedings of the Korean Information Science Society Conference
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    • 1999.10c
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    • pp.191-193
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    • 1999
  • 대 규모의 CORBA 시스템을 구축할 때 서로 다른 프로토콜을 갖는 여러 개의 ORB 도메인이 존재한다. 이러한 서로 다른 ORB 도메인들 간의 통신은 ORB 브리지를 통하여 수행된다. 따라서 전체 시스템에서 각 ORB 도메인 간의 브리지의 수는 가능하면 적어야 하고 각 브리지에 가중되는 부하 역시 적어야 한다. 본 논문에서는 이러한 문제를 그래프 개념으로 모델링하고 기본적인 그래프 연산들을 이용하여, 브리지의 수를 줄이고 각 브리지에 가중되는 부하를 균등하게 분할하여 전체 시스템을 구성하는 효율적인 알고리즘을 제안한다.

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A Hierarchical Graph Structure and Operations for Real-time A* Path finding and Dynamic Graph Problem (실시간 A* 길 찾기와 동적 그래프 문제를 위한 계층적 그래프 구조와 연산자)

  • Kim, Tae-Won;Cho, Kyung-Eun;Um, Ky-Hyun
    • Journal of Korea Game Society
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    • v.4 no.3
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    • pp.55-64
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    • 2004
  • A dynamic graph is suitable for representing and managing dynamic changable obstacles or terrain information in 2D/3D games such as RPG and Strategy Simulation Games. We propose a dynamic hierarchical graph model with fixed level to perform a quick A* path finding. We divide a graph into subgraphs by using space classification and space model, and construct a hierarchical graph. And then we perform a quick path fading on the graph by using our dynamic graph operators. With our experiments we show that this graph model has efficient properties for finding path in a dynamic game environment.

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Integration of Component Image Information and Design Information by Graph to Support Product Design Information Reuse (제품 설계 정보 재사용을 위한 그래프 기반의 부품 영상 정보와 설계 정보의 병합)

  • Lee, Hyung-Jae;Yang, Hyung-Jeong;Kim, Kyoung-Yun;Kim, Soo-Hyung;Kim, Sun-Hee
    • The KIPS Transactions:PartD
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    • v.13D no.7 s.110
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    • pp.1017-1026
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    • 2006
  • Recently, distributed collaborative development environment has been recognized an alternative environment for product development in which multidisciplinary participants are naturally involving. Reuse of Product design information has long been recognized as one of core requirements for efficient product development. This paper addresses an image-based retrieval system to support product design information reuse. In the system, product images obtained from multi-modal devices are utilized to reuse design information. The proposed system conducts the segmentation of a product image by using a labeling method and generates an attributed relational graph (ARG) that represents properties of segmented regions and their relationships. The generated ARG is extended by integrating corresponding part/assembly information. In this manner, the reuse of assembly design information using a product image has been realized. The main advantages of the presented system are following. First, the system is not dependent to specific design tools, because it utilizes multimedia images that can be obtained easily from peripheral devices. Second ratio-based features extracted from images enable image retrievals that contain various sizes of parts. Third, the system has shown outstanding search performance, because we applied various information of segmented part regions and their relationships between parts.

An Energy Estimation-based Routing Protocol for Maximizing Network Lifetime in Wireless Sensor Networks (무선 센서네트워크에서 네트워크 수명을 최대화하기 위한 에너지 추정 기반의 라우팅 프로토콜)

  • Hong, Ran-Kyung;Kweon, Ki-Suk;Ghim, Ho-Jin;Yoon, Hyun-Soo
    • Journal of KIISE:Computing Practices and Letters
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    • v.14 no.3
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    • pp.281-285
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    • 2008
  • Wireless sensor networks are closely related with the geometric environment in which they are deployed. We consider the probable case when a routing protocol runs on an environment with many complex obstacles like downtown surroundings. In addition, there are no unrealistic assumptions in order to increase practicality of the protocol. Our goal is to find a routing protocol for maximizing network lifetime by using only connectivity information in the complex sensor network environment. We propose a topology-based routing algorithm that accomplishes good performance in terms of network lifetime and routing complexity as measures. Our routing algorithm makes routing decision based on a weighted graph as topological abstraction of the complex network. The graph conduces to lifetime enhancement by giving alternative paths, distributing the skewed burden. An energy estimation method is used so as to maintain routing information without any additional cost. We show how our approach can be used to maximize network lifetime and by extensive simulation we prove that out approach gives good results in terms of both measures-network lifetime and routing complexity.