• Title/Summary/Keyword: Check path algorithm

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Development of Multi-agent Based Deadlock-Free AGV Simulator for Material Handling System (자재 취급 시스템을 위한 다중 에이전트 기반의 교착상태에 자유로운 AGV 시뮬레이터 개발)

  • Lee, Jae-Yong;Seo, Yoon-Ho
    • Journal of the Korea Society for Simulation
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    • v.17 no.2
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    • pp.91-103
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    • 2008
  • In order to simulate the behavior of automated manufacturing systems, the performance of material handling systems should be measured dynamically. Multi-Agent technology could be well adapted for the development of simulator for distributed and intelligent manufacture systems. A multi-agent system is composed of one coordination agent and multiple application agents. Issues in AGVS simulator can be classified by the set-up and operating problems. Decisions on the number of vehicles, bi- or uni-directional guide-path, etc. are fallen into the set-up problem category, while deadlock tree algorithm and conflict resolution are in operating problem. In this paper, a multi-agent based deadlock-free simulator for automated guided vehicle system(AGVS) are proposed through the use of multi-agent technologies and the development of deadlock-free algorithm. In this AGVS simulator proposed, well-known Floyd algorithm is used to create AGVS Guide path, through which AGVS move. Also, AGVs avoid vehicle conflict and deadlock using check path algorithm. And Moving vehicle agents are operated in real-time control by coordination agent. AGV position is dynamically calculated based on the concept of rolling time horizon. Simulator receives and presents operating information of vehicle in AGVS Gaunt chart. The performance of the proposed algorithm and developed simulator based on multi-agent are validated through set of experiments.

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An Efficient XML Query Processing Method using Path Containment Relationships (경로 포함 관계를 이용한 효율적인 XML 질의 처리기법)

  • 민경섭;김형주
    • Journal of KIISE:Databases
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    • v.31 no.2
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    • pp.183-194
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    • 2004
  • As XML is a do facto standard for a data exchange language, there have been several researches on efficient processing XML queries. The most important thing to consider when processing XML queries is how efficiently we can process path expressions in queries. Some previous works make results by performing a sequence of join operations on all records corresponding to labels in the path expression. Others works check the existence of paths in the query using an RDBMS's string comparison operator and make results by extracting the records corresponding to the paths. In this paper we suggested a new query planning algorithm based on path containment relationships and two join operators supporting the planning algorithm. The join operators use only the records related to the paths in a query as input data, scan them only once, and generate result data using a pipelining mechanism. By analysis and experiments, we confirmed that our techniques(a new query planning algorithm and two join operators) achieved significantly higher performance than other previous works.

Prediction and measurement of propagation path loss in indoor microcellular environments (실내 마이크로셀 환경에서 전파 경로손실의 예측과 측정)

  • 정백호;김채영;이숭복
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.34S no.11
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    • pp.1-8
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    • 1997
  • A prediction model is proposed to describe the path loss in propagation environment of indoor microcell. This model includes the lineal corridor for line--of-sight(LOS) and T-shaped corridor for non-line-of-sight(NLOS). In computation of receiving power the ray tracing technique based on image method is utilized and also reflected waves bounced on the walls and ceilings are considered. To check validity of the computed resuls cross checks between the predicted and measured are being made, which shows a close agreement for LOS case whereas somewhat disagreement for NLOS case. UTD technique is incorporated with propagation path determination algorithm in the treatment of NLOS case.

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Low Power Parallel Acquisition Scheme for UWB Systems (저전력 병렬탐색기법을 이용한 UWB시스템의 동기 획득)

  • Kim, Sang-In;Cho, Kyoung-Rok
    • The Journal of the Korea Contents Association
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    • v.7 no.1
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    • pp.147-154
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    • 2007
  • In this paper, we propose a new parallel search algorithm to acquire synchronization for UWB(Ultra Wideband) systems that reduces computation of the correlation. The conventional synchronization acquisition algorithms check all the possible signal phases simultaneously using multiple correlators. However it reduces the acquisition time, it makes high power consumption owing to increasing of correlation. The proposed algorithm divides the preamble signal to input the correlator into an m-bit bunch. We check the result of the correlation at first stage of an m-bit bunch data and predict whether it has some synchronization acquisition information or not. Thus, it eliminates the unnecessary operation and save the number of correlation. We evaluate the proposed algorithm under the AWGN and the multi-Path channel model with MATLAB. The proposed parallel search scheme reduces number of the correlation 65% on the AWGN and 20% on the multi-path fading channel.

A Study on Efficient CNU Algorithm for High Speed LDPC decoding in DVB-S2 (DVB-S2 기반 고속 LDPC 복호를 위한 효율적인 CNU 계산방식에 관한 연구)

  • Lim, Byeong-Su;Kim, Min-Hyuk;Jung, Ji-Won
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.9
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    • pp.1892-1897
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    • 2012
  • In this paper, efficient CNU(Check Node Update) algorithms are analyzed for high speed LDPC decoding in DVB-S2 standard. In aspect to CNU methods, there are some kinds of CNU methods. Among of them, MP (Min Product) method is quite often used in LDPC decoding. However MP needs LUT (Look Up Table) that is critical path in LDPC decoding speed. A new SC-NMS (Self-Corrected Normalized Min-Sum) method is proposed in the paper. NMS needs only normalized scaling factor instead of LUT and compensates the overestimation of MP approximation. In addition, SC method is proposed. It gives a faster convergence toward a decoded codeword. If a message change its sign between two iterations, it is not reliable and to avoid to propagate noisy information, its module is set to 0. The performance of SC-NMS has a little degrade compare to MP by 0.1 dB, however considering computational complexity and decoding speed, SC-NMS algorithm is optimal method for CNU algorithm.

A study of set route path avoiding traffic concentration in Mobile Ad hoc Network (MANET에서 트래픽 집중현상을 회피하는 경로설정에 관한 연구)

  • Oh, Dong-keun;Oh, Young-jun;Lee, Kang-whan
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2014.05a
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    • pp.781-783
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    • 2014
  • Mobile ad hoc network(MANET) consists of node that has mobility. MANET has increased overhead that caused by frequent topology changes. For reducing overhead, hierarchical network that communicates through cluster head node has been researched. When traffic is concentrated on cluster head node, cluster member node can't send message. To solve this problem, we proposed Step Parent algorithm. Proposed algorithm, cluster member node checks traffic of cluster head node using route path of other cluster head node in efficient coverage area. When cluster head node has increased traffic, cluster member node make a new route path by route path by routing path to another cluster head node. So cluster member node sends a message to destination node, we check improving delivery ratio.

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Control Algorithm for Stabilization of Tilt Angle of Unmanned Electric Bicycle

  • Han, Sangchul;Han, Jongkil;Ham, Woonchul
    • Transactions on Control, Automation and Systems Engineering
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    • v.3 no.3
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    • pp.176-180
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    • 2001
  • In this papers, we derive a simple kinematic and dynamic formulation of an unmanned electric bicycle. We also check the controllability of the stabilization problem of bicycle. We propose a new control algorithm for the self stabilization of unmanned bicycle with bounded wheel speed and steering angle by using nonlinear control based on the sliding patch and stuck phenomena which was introduced by W. Ham. We also propose a sort of optimal control strategy for steering angle and driving wheel speed that make the length of bicycle\`s path be the shortest. From the computer simulation results, we prove the validity of the proposed control algorithm.

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Route Optimization for Emergency Evacuation and Response in Disaster Area (재난지역에서의 대피·대응 동시수행을 위한 다중목적 긴급대피경로 최적화)

  • Kang, Changmo;Lee, Jongdal;Song, Jaejin;Jung, Kwangsu
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.2
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    • pp.617-626
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    • 2014
  • Lately, losses and damage from natural disasters have been increasing. Researchers across various fields in Korea are trying to come up with a response plan, but research for evacuation plans is still far from satisfactory. Hence this paper proposes a model that could find an optimized evacuation route for when disasters occur over wide areas. Development of the model used methods including the Dijkstra shortest path algorithm, feasible path method, genetic algorithm, and pareto efficiency. Computations used parallel computing (SPMD) for high performance. In addition, the developed model is applied to a virtual network to check the validity. Finally the adaptability of the model is verified on a real network by computating for Gumi 1stNational Industrial Complex. Computation results proved that this model is valid and applicable by comparison of the fitness values for before optimization and after optimization. This research can contribute to routing for responder vehicles as well as planning for evacuation by objective when disasters occur.

Estimation and Analysis of MIMO Channel Parameters using the SAGE Algorithm (SAGE 알고리즘을 이용한 MIMO 채널 파라미터 추정과 분석)

  • Kim, Joo-Seok;Yeo, Bong-Gu;Choi, Hong-Rak;Kim, Kyung-Seok
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.5
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    • pp.79-84
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    • 2017
  • This paper is a multi-input multi-path (Multiple-input multiple-output: MIMO) using a space-alternating generalized expectation maximization(SAGE) algorithm in the parameter channel and determine the channel estimation performance. Estimated by the algorithm, SAGE time-varying channel environment, the channel parameters estimated from the parameters of the channel measured in the island region 781 of the band in order to compare the performance and compares the original data. This allows you to check the performance of the algorithm SAGE and is highly stable to delay spread (Delay Spread), the diffusion angle of arrival (Arrive of Angular Spread) performance in terms of accuracy down through the SAGE algorithm for estimating a more general calculation parameters.

Study on Geometric Simulation System of Machining Operations (절삭 가공 시뮬레이션 시스템의 개발에 관한 연구)

  • 이상규;박재민;노형민
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.869-872
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    • 2003
  • This paper presents a geometric machining simulation algorithm to enhance the reliability and user-friendliness of a comprehensive computer aided process planning (CAPP) system by verifying generated NC data. In order to represent the complex machining geometry with high accuracy, the proposed algorithm is developed based on a boundary representative (B-rep) solid modelling kernel. Solid models are used to represent the part geometry. tool swept volume and material removal volume by Boolean unite and subtract operations. By integrating a machining simulation procedure into the CAPP system, the systematic analysis of the tool path can be implemented synthetically. To demonstrate and check the validity of suggested system, a simple example of simulation is represented and the result is discussed.

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