• Journal of KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.257-267
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• 2004

Most algorithms for handling distributed deadlock problem in the generalized request model use the diffusing computation technique where propagation of probes and backward propagation of replies carrying dependency information between processes are both required to detect deadlock Since fast deadlock detection is critical, we propose an algorithm that lets probes rather than replies carry the information required for deadlock detection. This helps to remove the backward propagation of replies and reduce the time cost for deadlock detection to almost half of that of the existing algorithms. Moreover, the proposed algorithm is extended to deal with concurrent executions, which achieves further improvement of deadlock detection time, whereas the current algorithms deal only with a single execution. We compare the performance of the proposed algorithm with that of the other algorithms through simulation experiments.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.10
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• pp.561-572
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• 2002

Deadlock detection in distributed systems is considered difficult since no single site knows the exact information on the whole system state. This paper proposes a time-efficient algorithm for distributed deadlock detection and resolution. The initiator of the algorithm propagates a deadlock detection message and builds a reduced wait-for graph from the information carried by the replies. The time required for deadlock detection is reduced to half of that of the other algorithms. Moreover, any deadlock reachable from the initiator is detected whereas most previous algorithms only find out whether the initiator is involved in deadlock. This feature accelerates the detection of deadlock. Resolution of the detected deadlock is also simplified and precisely specified, while the current algorithms either present no resolution scheme or simply abort the initiator of the algorithm upon detecting deadlock.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.5_6
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• pp.280-289
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• 2003

Deadlock recovery-based routing algorithms in wormhole networks have gained attraction due to low hardware complexity and high routing adaptability Progressive deadlock recovery techniques require a few dedicated resources to transmit deadlocked packets rather than killing them. Selection of deadlocked packets is primarily based on time-out value which should be carefully determined considering various traffic patterns or packet length. By its nature, current techniques using time-out accompany unignorable number of false deadlock detections especially in a heavy-loaded network or with long packet size. Moreover, when a deadlock occurs, more than one packet may be marked as deadlocked, which saturate the resources allocated for recovery. This paper proposes more accurate deadlock detection scheme which does not make use of time-out to declare deadlock. The proposed scheme reduces the probability to detect false deadlocks considerably. Furthermore, a single message is selected as deadlocked for each cycle of blocked messages, thereby eliminating recovery overheads.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06b
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• pp.24-29
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• 2008

여러 개의 작업이 동시에 작동 할 때 서로 다른 작업에서 특정한 로봇이나 장치를 사용하기 위하여 상대방의 작업이 끝나기를 기다리는 상태를 교착상태라 하며 생산공정에서는 효율성과 경제성 제고에 가장 중요한 문제 중 하나다. 지금까지 이러한 교착상태 확인은 도달성(reachability)기법이나 서브넷(Subnet)으로 분리하여 분석하는 기법 등이 가장 많이 사용 되었으나, 분석에 필요한 시간과 노력, 복잡성과 효율성에 있어서 효과적이지 못한 단점을 가지고 있다. 본 연구는 페트리넷(Petri Net)에서 모든 플레이스(Place) 간의 관계를 나타내는 추이(Transitive)행렬을 이용하여 교착상태가 나타날 가능성이 있는 자원공유 플레이스(Place)를 분석하여 교착상태를 검증하는 정책을 제시한다. 이를 위하여 교착상태를 확인할 수 있는 자원공유 플레이스의 관계를 정의하고, FMS(Flexible Manufacturing System) 모델을 이용하여 제안한 알고리즘의 성과를 검증한다.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06c
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• pp.343-346
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• 2011

대부분의 퍼즐 게임에서 발생 할 수 있는 중요한 문제 중 하나는 교착상태 문제이다. 본 논문에서는 이러한 교착상태를 해결하기 위해 퍼즐 게임을 그래프 기법으로 나타낸 뒤, 이를 이용한 새로운 교착상태 발견 기법인 Cycle Detection을 제안한다. 기존의 기법들은 알고리즘을 수행하는데 너무 많은 시간이 걸리거나, 패턴에 대한 데이터베이스가 구축되어 있어야 하기 때문에 실시간으로 교착상태를 발견하기엔 문제가 있다. 본 논문에서는 이러한 문제점을 해결하기 위하여 탐색해야 하는 노드의 개수를 최대한 줄이는 Local search 기법과 Pruning 기법을 적용하여 퍼즐 게임을 플레이하는 동안 실시간으로 교착상태를 발견할 수 있는 기법을 제안한다. 본 기법은 성능을 평가하기 위해 실제 퍼즐게임 환경에서 알고리즘을 수행하고, 그 결과로 검색하는 노드의 개수와 검색 시간을 기존의 기법과 비교하여 성능향상을 확인하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.3
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• pp.475-481
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• 2009

The frequency and probability of deadlock are influential factors in the design of algorithms for deadlock. However, little work has been done in this area because it's not easy to analyze how factors such as the characteristics of process or resource, resource request and release patterns, or the number of process affect the occurrence of deadlock. This study was designed to reduce remarkably the number of state by adapting the model 'state (a,b)t' to represent the resource allocation state, as well as to include the effect of resource error rate and recovery rate in the system analysis. Various formulas about deadlock occurrence were resulted in this study such as the average time interval of deadlock, the probability that a process requesting a resource waits or deadlocks, and the probability that a request deadlocks in a cycle of length 2.

• Journal of the Korea Society for Simulation
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• v.17 no.3
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• pp.75-83
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• 2008

A deadlock is a condition in which the excessive demand for the resources being used by others causes activities to stop and it is one of the important problems in process control system to detect and prevent deadlocks. While the reachability analyze methods or divide subnets for analyzing methods are well used, it requires a lot of times and effects to analyze the detection of the deadlock status. Furthermore, it could not be effective if the model is complex or huge. Therefore, it is necessary to develop a new and more efficient deadlock detection algorithm. In this paper, a deadlock detection conditions after analyzed the Petri Net using the transitive matrix has been proposed to solve these problems. For presenting the results, the suggested deadlock detection algorithm was also adapted to an illustrated FMS (Flexible Manufacturing System) model.

• Journal of the Korea Society of Computer and Information
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• v.6 no.2
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• pp.34-40
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• 2001

This thesis shows that the edge-chasing deadlock detection algorithm of Choudhary fails to remove the existing deadlocks after committing the transaction whose priority is lowest on the transaction wait-fer path. A modified algorithm that solves this problem is proposed.

• Journal of the Korea Society for Simulation
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• v.15 no.1
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• pp.1-10
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• 2006

The Flexible Management System (FMS) consists of parallel and concurrent machines, pieces of equipment, and carrying systems classified as buffers, tools, and routers, respectively. The concurrent flow of multiple productions in a system is competed with one another for resources and this resulting competition can cause a deadlock in FMS. Since a deadlock is a condition in which the excessive demand for the resources being used by others causes activities to stop, it is very important to detect and prevent a deadlock. Herein a new algorithm has been studied in order to detect and prevent deadlocks, after defining a relationship between the general places and resource share places in Petri nets like as DAPN: Deadlock Avoidance Petri Net. For presenting the results, the suggested algorithms were also adapted to the models that demonstrated FMS features.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2131-2136
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• 2016

Before Industry 4.0, a purpose of manufacturing processes is simply overcoming the weakness of product line. However, Industry 4.0 should determine its method of work of facilities' own accord. Manufacturing processes such as FMS, AMS, MAS have been developed in these procedures, but there are possibilities of deadlock that can be happened for the reason of machine, agent or resource sharing. There were many studies to solve this problem. However, studies about prevention of deadlock happened in the situation that manufacturing processes are reconfigured dinamically because of human's intervention are incomplete. This paper proposes the model of the situation reconfigured dinamically and the method to prevent the deadlock in this situation. The proposed method adjusts production and manufacturing time by broadcasting time error messages to machines around when the manufacturing time of machine intervened by human is changed. Through this, it is anticipated to prevent the deadlock if conditions of the product line are changed.