• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 B
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• pp.838-840
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• 1999

In this paper, modeling and analysis of discrete event systems by temporal logic frame works and petri net is considered. The reachability tree of the petri net can be used to solve the safeness, boundedness, conservation and coverability problems of discrete event systems. But the reachability tree of the petri net do not solve reachability and liveness problems in general. We proposed a method that synthesised the petri net and the temporal logic frameworks. This method slove some problems of petri net by logical representation of temporal logic frameworks.

• 한국시뮬레이션학회논문지
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• 제1권1호
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• pp.37-47
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• 1992

This paper proposes an analysis method of petri nets(PNs) using the relational algebra(RA). More wpecifically, we represent PNs in relations of the relational model. Based on such representation, we first develop an algorithm for generating reachability trees of PNs. we then develop an algorithm for generating reachability trees of PNs. We then develop algorithms for analyzing properties of PNs, such as boundedness, conservation, coverability, reachability, and liveness. The advantage of this approach is as follows: First, the algorithms represented by RA can be easity converted to a query language such as SQL of the widely used, commerical relational database management systems(DBMSs). Second, we can alleviate the problem of state space explosion because relational DBMSs can handle large amounts of data efficiently. Finally, we can use the DBMS's query language to interpret the Petri nets and make simulation.

• 한국정보과학회논문지:정보통신
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• 제32권6호
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• pp.745-752
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• 2005

BGP[1]는 광대역 인터넷에 사용되는 유일한 라우팅 방식으로서 인터넷의 계층구조와 자신의 정책에 의해서 경로를 선정한다. BGP 라우터는 일부의 인근 BGP 라우터에 대해서만 선택적으로 라우팅 정보를 공표하기 때문에 링크가 연결되었다고 해서 출발지 노드에서 목적지 노드까지의 라우팅 정보가 도달되지는 않는다. 특히 바이러스나 재난으로 인하여 광범위에 걸쳐서 많은 BGP 라우터가 다운되는 유사시에 인터넷의 연결성을 유지하기 위하여 BGP는 평소에 도달할 수 없는 경로도 제한적으로 도달할 수 있어야 한다. 이 논문은 BGP 백업 라우팅의 요구사항을 나열한 후 이러한 사항을 최대로 만족하는 백업 라우팅 규칙을 찾아본 결과 기존 방식이 안고 있던 대부분의 단점이 해결된 백업방식을 도출하였다. 제안되는 백업방식은 우선 BGP 백업 라우팅은 네트웍의 피해정도에 따라 3단계로 동작한다. 이 규칙 하에서 BGP 라우터는 평소에는 0단계에서 정의되는 경로만을 사용하다가 BGP 라우터의 손상범위에 따라서 1단계로, 손상범위가 더 커지면 2단계로 사용범위를 확장한다. 또한 이 논문은 제안된 백업 방식이 네크웍의 안정성(stability)과 안전성(safeness)을 보장함을 증명하였다. 그 결과 제안된 백업방식은 사소한 지역적인 네트웍 사고에서부터 전체적인 심한 네트웍 사고에 이르는 모든 사고에 대해서 적응력 있게 대처하여서 강력한 경로의 도달성을 항시 제공한다.

• 한국통신학회논문지
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• 제33권10A호
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• pp.956-963
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• 2008

다중 홉 무선 ad hoc 네트워크에서 방송은 경로 탐색과 주소 설정 등 많은 응용 작업들을 지원해 주는 기본적인 동작이다. 플로딩을 이용한 방송은 네트워크상에서 방송 폭풍 문제라고 언급되는 중복성, 경쟁, 충돌문제 등을 야기한다. 무선 ad hoc 네트워크를 위한 여러 가지 방송 기법들은 단순 플로딩 기법 보다 우수한 성능을 얻기 위해 제안되었다. 재방송 실행 유무를 결정하는 방법은 다양한 토폴로지 상에서 패킷의 도착율과 효율성 사이에 딜레마를 갖는다. 본 논문에서는 패킷의 도착율 저하 없이, 필요 없는 재방송 패킷들을 줄여서 효율성을 높이기 위한 향상된 방송 알고리즘을 제안한다. 시뮬레이션 결과를 통해 제안한 기법이 기존의 기법들 보다 우수한 도착율과 효율성을 제공함을 보인다.

• Journal of Information Processing Systems
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• 제16권1호
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• pp.201-209
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• 2020

The graph data structure is popular because it can intuitively represent real-world knowledge. Graph databases have attracted attention in academia and industry because they can be used to maintain graph data and allow users to mine knowledge. Mining reachability relationships between two nodes in a graph, termed reachability query processing, is an important functionality of graph databases. Online traversals, such as the breadth-first and depth-first search, are inefficient in processing reachability queries when dealing with large-scale graphs. Labeling schemes have been proposed to overcome these disadvantages. The state-of-the-art is the 2-hop labeling scheme: each node has in and out labels containing reachable node IDs as integers. Unfortunately, existing 2-hop labeling schemes generate huge 2-hop label sizes because they only consider local features, such as degrees. In this paper, we propose a more efficient 2-hop label size reduction approach. We consider the topological sort index, which is a global feature. A linear combination is suggested for utilizing both local and global features. We conduct experiments over real-world and synthetic directed acyclic graph datasets and show that the proposed approach generates smaller labels than existing approaches.

• 한국정보처리학회논문지
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• 제5권4호
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• pp.995-1004
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• 1998

본 논문은 LTS 프로세스 명세 검증을 위해 프로토콜의 행위와 상태에 대한 deadlock, livelock, reachability, liveness 검증을 위한 모델 검증기 구현에 대해 기술하였다. Modal mu-calculus를 사용하여 구현된 모델 검증기는 modal logic으로 표현된 프로토콜 특성이 LTS 명세하에서 만족하는지를 자동적으로 검증해 주는 model checking 도구이고 LTS 명세의 Safety와 Liveness 검증에 매우 강력한 성능을 보이는 것을 구현을 통해 실험적으로 증명하였다. 제시된 도구는 Windows NT 환경하에서 IBM PC로 $C^{++}$언어를 사용하여 구현되었다.

• 대한산업공학회지
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• 제38권3호
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• pp.173-181
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• 2012

The size and layout of user interface components need to be optimally designed in terms of reachability, visibility, clearance, and compatibility in order for efficient and effective use of products. The present study develops an ergonomic design method which optimizes the size and layout of user interface components using adaptive genetic algorithm. The developed design method determines a near-optimal design which maximizes the aggregated score of 4 ergonomic design criteria (reachability, visibility, clearance, and compatibility). The adaptive genetic algorithm used in the present study finds a near-optimum by automatically adjusting the key parameter (probability of mutation) of traditional genetic algorithm according to the characteristic of current solutions. Since the adaptive mechanism partially helps to overcome the local optimality problem, the probability of finding the near-optimum has been substantially improved. To evaluate the effectiveness of the developed design method, the present study applied it to the user interface design for a portable wireless communication radio.

• 한국정밀공학회지
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• 제17권2호
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• pp.176-184
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• 2000

Possible representation methods for the product structure have been compared and analyzed to determine optimal disassembly path of a product. Petri net is selected as the most optimal method to represent disassembly path of the product. In this method, a reachability tree for the product is generated and disassembly time for each path is calculated. A path with the smallest disassembly time is selected as the optimal path. A software far DPN(Disassembly Petri Net) has been developed and applied to search the optimal disassembly path for a ballpoint pen disassembly process as an example.

• 한국정보처리학회논문지
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• 제7권6호
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• pp.1874-1885
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• 2000

When a receiver of ciphertext message can not decrypt a message because he has lost his private-key, the private-key of receiver and session-key of the message should be recovered. In this paper, we developed an Encapsulation based Key Recovery System (EKRS). EKRS is a new key encapsulation based key recovery system which is characterized by secretly choice of KRA, randomized target keys. n-way recovery type, and useful for commercial key recovery. EKRS is formally specified by a pictorial model, an Extended Cryptographic Timed Petri Net (ECTPN). Secure information flow and reachability of a session-key are verified by using reachability graph of ECTPN. EKRS, executing over a Public Key Infrastructure, can be used as a security solution in Web based applications such as CALS, EC an EDI.

• 전기학회논문지
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• 제56권1호
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• pp.167-173
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• 2007

This paper describes a redundancy resolution based method for determining an optimal initial configuration of a humanoid robot for holding an object. There are three important aspects for a humanoid robot to be able to hold an object. Those three aspects are the reachability that guarantees the robot to reach the object, the stability that guarantees the robot to remain stable while moving or holding the object, and the manipulability that makes the robot manipulate the object dexterously. In this paper, a humanoid robot with 20 degrees of freedom is considered. The humanoid robot is kinematically redundant and has infinite number of solutions for the initial configuration problem. The complex three-dimensional redundancy resolution problem is divided into two simple two-dimensional redundancy resolution problems by incorporating the symmetry of the problem, robot's moving capability, and the geometrical characteristics of the given robot. An optimal solution with respect to the reachability, the stability, and the manipulability is obtained by solving these two redundancy resolution problems.