• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.101-106
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• 2011

In this paper, our goal is to design the controller which operates a manufacturing system, discrete event system, guaranteeing user specification. In specially, based on supervisory control theory W. M. Wonham, our work consists in performing the controller using Petri nets possible parallelism. In addition, we consider the problem of allocation for resources sharing of the issues to consider when designing using Petri net. The controller can be generated by synthesis of user specification model and plant model after giving the management for the resource sharing. This created controller can control the deadlock and starvation which can occur in the case with resource sharing. Previous studies proposed the Constrained Synchronous Reachability graph to synthesis of the two Petri nets models. Therefore, we provide the controlled system which forbids a deadlock and starvation using the result of previous studies.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1997.10a
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• pp.125-125
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• 1997

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1110-1115
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• 1991

Tne mathematical modeling and analysis results of a dataflow logic solving processor(DFLSP) for programmable logic controller(PLC) are proposed in this paper. The logic program language is formalized using a dataflow graph model. From this dataflow graph, the instruction precedence relationship, and deadlock problems, which are major properties of a logic program, are described.

• Journal of the Korea Society for Simulation
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• v.8 no.1
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• pp.77-88
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• 1999

There are two approaches to handle the Causality Error in parallel and distributed simulation. One approach is based on the conservative time synchronization and the other is the optimistic time synchronization. In this paper an efficient null message reduction method for the conservative time synchronization approach is suggested with the experimental results, which could improve performance of simulation and avoid deadlock situations.

• The Transactions of the Korea Information Processing Society
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• v.3 no.4
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• pp.803-816
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• 1996

It is possible to prevent deadlock if the priority which is conventionally given to transactions is endowed to data items and the transactions with the highest priority among transactions accessing the data item is allowed to proceed. Based on this observation, we proposed a Data-Priority Based Locking Protocol(DPLP) and evaluated its performance against known locking protocols in Real Time Database Management System(RTDBMS). Transaction inter-arrival time(IAT) was varied to determine success ratio, average-lateness, confict ratio and restart ratio, In these simulations we verified that the proposed DPLP performs better than the other protocols.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.314-314
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• 1996

We investigate the scheduling problem for periodic job shops with blocking. We develop Petri net models for periodic job shops with finite buffers. A buffer control method would allow the jobs to enter the input buffer of the next machine in the order for which they are completed. We discuss difficulties in using such a random order buffer control method and random access buffers. We thus propose an alternative buffer control policy that restricts the jobs to enter the input buffer of the next machine in a predetermined order. The buffer control method simplifies job flows and control systems. Further, it requires only a cost-effective simple sequential buffer. We show that the periodic scheduling model with finite buffers using the buffer control policy can be transformed into an equivalent periodic scheduling model with no buffer, which is modeled as a timed marked graph. We characterize the structural properties for deadlock detection. Finally, we develop a mixed integer programming model for the no buffer problem that finds a deadlock-free optimal sequence that minimizes the cycle time.

• BMB Reports
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• v.49 no.7
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• pp.355-356
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• 2016

The THO/TREX complex consists of several conserved subunits and is required for mRNA export. In metazoans, THO/TREX binds a subset of mRNAs during RNA splicing, and facilitates their nuclear export. How THO/TREX selects RNA targets is, however, incompletely understood. In our recent study, we reported that THO is loaded onto Piwi-interacting RNA (piRNA) precursor transcripts independent of splicing, and facilitates convergent transcription in Drosophila ovary. The precursors are later processed into mature piRNAs, small noncoding RNAs that silence transposable elements (TEs). We observed that piRNAs originating from dual-strand clusters, where precursors are transcribed from both strands, were specifically affected by THO mutation. Analysis of THO-bound RNAs showed enrichment of dual-strand cluster transcripts. Interestingly, THO loading onto piRNA precursors was dependent on Cutoff (Cuff), which comprises the Rhino-Deadlock-Cutoff (RDC) complex that is recruited to dual-strand clusters by recognizing H3K9me3 and licenses convergent transcription from he cluster. We also found that THO mutation affected transcription from dual-strand clusters. Therefore, we concluded that THO/TREX is recruited to dual-strand piRNA clusters, independent of splicing events, via multi-protein interactions with chromatin structure. Then, it facilitates transcription likely by suppressing premature termination to ensure adequate expression of piRNA precursors.

• Journal of the Korea Society for Simulation
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• v.17 no.3
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• pp.85-94
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• 2008

Automated Guided Vehicles (AGVs) are important equipment in automated container terminals. To utilize AGVs for transporting containers from a position to another, the deadlock is a serious problem that must be solved before they are deployed to real operations. This study assumes that traveling area for AGVs are divided into a large number of grid-blocks and, as a method of traffic control, grid-blocks are reserved in advance during the travel of AGVs. The purposes of the reservation are to make the room between AGVs and to prevent deadlocks. Because the size of an AGV is much larger than the size of a grid-block on guide paths, this study assumes an AGV may occupy more than one grid-block at the same time. This study suggests a method for constructing a table of reservation schedules by using a simulation. A sensitivity analysis was conducted to evaluate the performance of the reservation method in this study.

• Journal of Internet Computing and Services
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• v.7 no.6
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• pp.79-86
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• 2006

Many of concurrency control for client-sewer database systems have been proposed and studied in the literature. However, commonly known schemes do not manage to the case of dramatic changes in data contention because the data contention of database systems is changed for each cases. In this paper, we propose o hybrid concurrency control. The proposed scheme uses a optimistic scheme for the first-run transactions and a pessimistic scheme for the second-run transactions. By pre-claiming locks in the second phase, deadlocks which ore possible in pessimistic based concurrency control are prevented in our approach. In addition, the scheme ensures at most one re-execution even if the validation in the optimistic phase fails. By a detailed simulation, this paper examines the behaviors of the Distributed Optimistic Concurrency Control and the proposed scheme. The simulation study shows our scheme outperforms Distributed Optimistic Concurrency Control in our experimental result.

• Journal of Korea Multimedia Society
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• v.7 no.6
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• pp.791-797
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• 2004

We proposed a novel digital video watermarking that embeds dual watermarks in the block DCT domain to solve the deadlock problem. Daul watermarks are composed of private watermarks and robust blind watermarks. Firstly, private watermarks are embedded into the lowest AC coefficients of the P or B-frames in accordance with the motion direction gained from a previous frame. Secondly, blind watermarks that have the robustness are inserted into the DC coefficients of the I-frames using a private key made from temporal I-frame motion information. Thus, when a deadlock situation occurs, the proposed algorithm can efficiently solve the problem. Experimental results confirmed that the proposed algorithm can produce good subjective and objective results for MPEG coding with a variety of bit rates. Furthermore, the proposed watermarking algorithm can potentially be applied to broadcasting monitoring systems due to its simplicity and high robustness.