• The Transactions of the Korea Information Processing Society
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• v.6 no.10
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• pp.2740-2751
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• 1999

Critical to more widespread use of Internet telephony are the smooth interoperability with the existing telephone network and the improved quality of voice connections. Of these requirements, this interoperability comes through the use of Internet Telephony Gateway's which perform protocol translation between an IP network and the Public Switched Telephone Network. In this paper, we have focused on the necessity and possibility of interoperability, and furthermore derives the necessary requirements for interoperability between IP networks and PSTN. For this purpose, we have analyzed the signaling protocols for gateway system. Then, we have modelled the inter-working part using the Petri-Net model. Through reachability trees of the Petri-Net model, we have confirmed that interoperability is possible, and that characteristics of deadlock, liveness, and boundness are satisfied.

• East Asian Economic Review
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• v.22 no.1
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• pp.3-28
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• 2018

This article discusses the deadlock in the WTO on multilateral harmonization of nonpreferential rules of origin (RoO) and reviews some of the RoO included in recent preferential trade agreements. We argue that there is a trend towards adoption of similar approaches and that this suggests that cooperation to reduce the trade-impeding effects of differences in RoO across jurisdictions is more feasible than often is assumed by observers and policymakers. From a trade facilitation perspective such cooperation could be based on plurilateral initiatives under the umbrella of the WTO. These could include a focus on pursuit of greater convergence between preferential and nonpreferential RoO helping to achieve the long-standing goal of moving towards harmonization of rules of origin.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.5
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• pp.734-738
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• 2010

Object Generator is a software to provide simulation object data(aircraft, ship, submarine, missile, torpedo) for sumulators in LBTS(Land Based Test System). but there is a burden to the system, because Object generator needs to send many object's data, display objects in a tactical screen, show object's information in a list in 1 second. This paper suggests a parallel software structure taking a few factors(deadlock, dependency) into consideration. At last, the paper shows the performance of the parallel structure's software compared with the former structure's software.

• Journal of Korean Society of Transportation
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• v.12 no.3
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• pp.49-64
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• 1994

The development of a mathematical modular framework based on Petri Network theory to model a traffic network is the subject of this paper. Traffic intersections are the primitive elements of a transportation network and are characterized as event driven and asynchronous systems. Petri network have been utilized to model these discrete event systems; further analysis of their structure can reveal information relevant to the concurrency, parallelism, synchronization, and deadlock avoidance issuse. The Petri-net based model of a generic traffic junction is presented. These modular networks are effective in synchronizing their components and can be used for modeling purposes of an asynchronous large scale transportation system. The derived model is suitable for simulations on a multiprocessor computer since its program execution safety is secured. The software pseudocode for simulating a transportation network model on a multiprocessor system is presented.

• Journal of Korea Multimedia Society
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• v.6 no.2
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• pp.301-308
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• 2003

In this paper, we propose a multicast ATM switch that reduces traffic load by using the method of storing unicast cells and multicast cells separately according to the type of the cells. The switch is based on a shared memory type to reduce HOL blocking and deadlock. In the proposed switch, we use a control scheme that schedules stored cells to output ports to reduce the loss of traffic cells and to output effectively. We analyzed the Performance of the proposed switch through the computer simulation and the results have shown the effectiveness of the switch.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.11a
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• pp.67-74
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• 2003

Stream servers are for supplying multimedia stream data to users through the internet such as movies and musics without discontinuation. A typical stream server is designed roughly by considering the characteristics of stream services and by employing processors, memory, PCI bus, Ethernet, TOE and disks. This study focuses on deciding the priority for using resources such as PCI bus, buffer memory and TOE buffer, which have limited capacities in a typical stream server. The simulation study shows that the top priority for using PCI bus for normal streaming services should be given to the operation that sends data from buffer memory to TOE buffer Giving priority for using PCI bus to other operation such as sending data from disks to memory results in deadlock Phenomenon.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.861-869
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• 2023

This article proposes a novel approach to measure the performance of Safety-Critical Systems (SCS). Such systems contain multiple processing nodes that communicate with each other is modeled by a Petri nets (PN). The paper uses the PN for the performance evaluation of SCS. A set of ordinary differential equations (ODEs) is derived from the Petri net model that represent the state of the system, and the solutions can be used to measure the system's performance. The proposed method can avoid the state space explosion problem and also introduces new metrics of performance, along with their measurement: deadlock, liveness, stability, boundedness, and steady state. The proposed technique is applied to Shutdown System (SDS) of Nuclear Power Plant (NPP). We obtained 99.887% accuracy of performance measurement, which proves the effectiveness of our approach.

• Annual Conference of KIPS
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• 2023.05a
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• pp.149-150
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• 2023

ROS2 코드에서, multi-threaded executor 은 여러 메시지 또는 이벤트를 병렬로 처리할 수 있도록 복수의 스레드를 만든다. Multi-threaded executor 을 사용하면 프로그램 성능이 가속화되고 메모리를 경제적으로 사용할 수 있지만, 하나의 시스템 자원을 여러 개의 프로세스가 동시에 참조하거나 수정하기 때문에 deadlock 등의 여러 문제가 발생한다. 이 논문에서는 libclang 인터페이스를 이용해 ROS2 코드를 구문 분석하고 스레드 안전성을 평가하는 방법과 그 한계점, 향후 연구 방향에 대해 논한다.

• Annual Conference of KIPS
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• 2007.05a
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• pp.751-754
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• 2007

본 연구에서는 유연생산시스템에서의 교착상태 확인 및 회피 알고리즘을 추이적 행렬을 이용하여 제안한다. 추이적행렬은 플레이스와 플레이스간의 관계를 표현함으로 마킹의 흐름을 플레이스와 트랜지션간의 관계형에서 상태와 상태간의 관계를 표현함으로 상태의 변화 검증에 편리하다. 교착상태 확인 및 회피 알고리즘을 제시하고, 기존에 발표되어진 siphon과 DAPN알고리즘간의 비료 검토를 통하여 제안한 알고리즘의 유용성을 검증하였다.

• The Journal of Korea Robotics Society
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• v.19 no.3
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• pp.281-286
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• 2024

This paper describes the solution method of Team AIRLAB used to participate in the League of Robot Runners Competition which tackles the problem of Lifelong Multi-agent Pathfinding (MAPF). In lifelong MAPF, multiple agents are tasked to navigate to their respective goal locations where new goals are consecutively revealed once they reach initial goals. The agents need to avoid collisions and deadlock situations while they navigate to perform tasks. Our method consists of (i) Puzzle Heuristics, (ii) MAPF-LNS2, and (iii) RHCR. The Puzzle Heuristics is our own algorithm that generates a compact heuristic table contributing to reduce memory consumption and computation time. MAPF-LNS2 and RHCR are state-of-the-art algorithms for MAPF. By combining these three algorithms, our method can improve the efficiency of paths for all agents significantly.