• Journal of applied mathematics & informatics
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• v.9 no.2
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• pp.607-620
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• 2002

In this paper, we consider the updating problems to reconstruct the biconnected-components and to reconstruct the weighted shortest path in response to the topology change of the network. We propose two distributed algorithms. The first algorithm solves the updating problem that reconstructs the biconnected-components after the several processors and links are added and deleted. Its bit complexity is O((n'+a+d)log n'), its message complexity is O(n'+a+d), the ideal time complexity is O(n'), and the space complexity is O(e long n+e' log n'). The second algorithm solves the updating problem that reconstructs the weighted shortest path. Its message complexity and ideal-time complexity are $O(u^2+a+n')$ respectively.

• International Journal of Control, Automation, and Systems
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• v.4 no.4
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• pp.466-479
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• 2006

This paper addresses a formation navigation issue for a group of mobile robots passing through an environment with either static or moving obstacles meanwhile keeping a fixed formation shape. Based on Lyapunov function and graph theory, a NN formation control is proposed, which guarantees to maintain a formation if the formation pattern is $C^k,\;k\geq1$. In the process of navigation, the leader can generate a proper trajectory to lead formation and avoid moving obstacles according to the obtained information. An evolutionary computational technique using particle swarm optimization (PSO) is proposed for motion planning so that the formation is kept as $C^1$ function. The simulation results demonstrate that this algorithm is effective and the experimental studies validate the formation ability of the multiple mobile robots system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.418-420
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• 2015

The SNOMED CT browser is a system for searching and browsing of a huge volume of medical terminologies included in SNOMED CT. Previous browsers provide a simple list-up of search results while they are similar from each other. It leads to a serious confusion in selecting an appropriate term among them. This paper presents a novel browser system which provides a comparative search of search results. To do this, the proposed system includes a terminology search module, a topology search module, and a sub-graph generation module for the results.

• Honam Mathematical Journal
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• v.30 no.4
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• pp.589-602
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• 2008

As a survey-type article, the paper reviews various digital topological utilities from digital covering theory. Digital covering theory has strongly contributed to the calculation of the digital k-fundamental group of both a digital space(a set with k-adjacency or digital k-graph) and a digital product. Furthermore, it has been used in classifying digital spaces, establishing almost Van Kampen theory which is the digital version of van Kampen theorem in algebrate topology, developing the generalized universal covering property, and so forth. Finally, we remark on the digital k-surface structure of a Cartesian product of two simple closed $k_i$-curves in ${\mathbf{Z}}^n$, $i{\in}{1,2}$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.339-343
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• 1992

For the analysis of dynamic behavior of dynamic behavior of multibody systems by cartesian coordinate method, maximal sets of generalized coordinates and maximum numbers of differential equation and constraints must be considered. Therefore the inefficiency of the increase of CPU time is occurred. This paper is to analyze the dynamic system by using the relative coordinate method without violating the geometric condition of systems. The graph theory and system topology were used for this study. The dynamic systems could be analyzed by the automatic generation of the informations like equation of motion, constraints, and external forces etc. And the results were compared and verified with dynamic commercial package DADS.

• Journal of Korean Society of Disaster and Security
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• v.8 no.1
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• pp.1-4
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• 2015

If a disaster occurs in the underground like subway, disaster response system should minimize the casualties. It must quickly guide passengers to a safe evacuation route. But sometimes the system does not work properly. And then they need distributed disaster response system which make decision autonomously. In this study, we proposed the evacuation route analysis and induction algorithms for creationg passenger evacuation route and offering optimal evacuation route.

• Journal of Communications and Networks
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• v.9 no.4
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• pp.350-355
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• 2007

Border gateway protocol allows autonomous systems(ASes) to apply diverse routing policies for selecting routes and for propagating reachability information to other ASes. Although a significant number of studies have been focused on the Internet topology, little is known about what routing policies network operators employ to configure their networks. In this paper, we infer and characterize routing policies employed in the Internet. We find that routes learned from customers are preferred over those from peers and providers, and those from peers are typically preferred over those from providers. We present an algorithm for inferring and characterizing export policies. We show that ASes announce their prefixes to a selected subset of providers to perform traffic engineering for incoming traffic. We find that the selective announcement routing policies imply that there are much less available paths in the Internet than shown in the AS connectivity graph, and can make the Internet extremely sensitive to failure events. We hope that our findings will help network operators in designing routing policies.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.430-432
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• 2004

Multicasting is an efficient means of one to many (or many to many) communications. Due to the frequent and unpredictable topology changes, multicast still remains as challenge and no one-size-fits-all protocol could serve all kinds of needs in ad hoc network. Protocols and approaches currently proposed on this issue could be classified mainly into four categories, tree-based, meshed-based, statelessness and hybrid. In this article, we borrow the concept of Eulerian ring in graph theory and propose a novel ring-based multicast framework--Hierarchical Eulerian Ring-Oriented Multicast Architecture (HEROMA) over wireless mobile Ad hoc network. It is familiar with hybrid protocol based on mesh and tree who concentrates on efficiency and robustness simultaneously. Architecture and recovery algorithm of HEROMA are investigated in details. Simulation result is also presented, which show different level of improvements on end-to-end delay in scenario of small scale.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.04a
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• pp.189-192
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• 2005

공학시스템의 설계 문제는 시스템 구성이 복잡하고, 구조적으로 열려있으며, 전기, 기계, 유압, 열등의 서로 다른 에너지 도메인 구성 요소를 포함한다. 최적의 설계를 위해서는 각 도메인에 대한 통합된 설계 방법과 자동적이고 구조적으로 열린 공간에 대한 효율적인 탐색방법이 요구된다. 본 논문은 도메인에 독립적이며 모델링과 해석에 장점을 가진 본드 그래프 (bond graph)와 대규모 공간 해의 탐색에 접합한 진화 알고리즘의 일종인 유전자 프로그래밍(Genetic Programming)을 결합하여 멀티 도메인 동적시스템에 대한 디자인 해를 자동적으로 생성해주는 설계 방법을 제시하고, 제안된 설계방법의 효용성을 입증하기 위해서 이를 아나로그 필터 설계에 문제에 적용하였다.

• Journal of Information Processing Systems
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• v.10 no.2
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• pp.193-214
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• 2014

Load balancing is the major benefit of any distributed system. To facilitate this advantage, task duplication and migration methodologies are employed. As this paper deals with dependent tasks (DAG), we used duplication. Task duplication reduces the overall schedule length of DAG along-with load balancing. This paper proposes a new task duplication algorithm at the time of tasks assignment on various processors. With the intention of conducting proposed algorithm performance computation; simulation has been done on the Netbeans IDE. The mesh topology of a distributed system is simulated at this juncture. For task duplication, overall schedule length of DAG is the main parameter that decides the performance of a proposed duplication algorithm. After obtaining the results we compared our performance with arbitrary task assignment, CAWF and HEFT-TD algorithms. Additionally, we also compared the complexity of the proposed algorithm with the Duplication Based Bottom Up scheduling (DBUS) and Heterogeneous Earliest Finish Time with Task Duplication (HEFT-TD).