• Title/Summary/Keyword: Node-Link Model

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A Kth Shortest Path Algorithm with the Link-Based Label Setting Approach and Its Application for An Alternative Routes Selection (링크표지확정 다수경로탐색 알고리즘과 대안경로선정을 위한 활용)

  • Lee, Mee-Young;Baik, Nam-Cheol;Kang, Weon-Eui;Shin, Seong-Il
    • Journal of Korean Society of Transportation
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    • v.22 no.4 s.75
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    • pp.85-96
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    • 2004
  • Given a Path represented by a sequence of link numbers in a transportation network, the reasonable path is defined as a path that any link is appeared multiple times in it. Application of the link labelmethod(LLM) to the shortest path algorithms(SPA) enables to model the reasonable path choice behavior in urban networks. This study aims at expanding the LLM to a Kth shortest path algorithms(KPSA), which adopts the node label setting method. The small-scaled network test demonstrated that the proposed algorithm works correctly and the revised Sioux fall network test showed that the path choice behaviors are reasonably reflected. In the large-scaled network based on the South Korea peninsula, drivers' route diversion perceptions are included as cost terms in total cost. The algorithm may be applied as an alternative route information tools for the deployment of ATIS.

Development of Vehicle Queue Length Estimation Model Using Deep Learning (딥러닝을 활용한 차량대기길이 추정모형 개발)

  • Lee, Yong-Ju;Hwang, Jae-Seong;Kim, Soo-Hee;Lee, Choul-Ki
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.17 no.2
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    • pp.39-57
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    • 2018
  • The purpose of this study was to construct an artificial intelligence model that learns and estimates the relationship between vehicle queue length and link travel time in urban areas. The vehicle queue length estimation model is modeled by three models. First of all, classify whether vehicle queue is a link overflow and estimate the vehicle queue length in the link overflow and non-overflow situations. Deep learning model is implemented as Tensorflow. All models are based DNN structure, and network structure which shows minimum error after learning and testing is selected by diversifying hidden layer and node number. The accuracy of the vehicle queue link overflow classification model was 98%, and the error of the vehicle queue estimation model in case of non-overflow and overflow situation was less than 15% and less than 5%, respectively. The average error per link was about 12%. Compared with the detecting data-based method, the error was reduced by about 39%.

A Multi-Layer Graphical Model for Constrained Spectral Segmentation

  • Kim, Tae Hoon;Lee, Kyoung Mu;Lee, Sang Uk
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2011.07a
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    • pp.437-438
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    • 2011
  • Spectral segmentation is a major trend in image segmentation. Specially, constrained spectral segmentation, inspired by the user-given inputs, remains its challenging task. Since it makes use of the spectrum of the affinity matrix of a given image, its overall quality depends mainly on how to design the graphical model. In this work, we propose a sparse, multi-layer graphical model, where the pixels and the over-segmented regions are the graph nodes. Here, the graph affinities are computed by using the must-link and cannot-link constraints as well as the likelihoods that each node has a specific label. They are then used to simultaneously cluster all pixels and regions into visually coherent groups across all layers in a single multi-layer framework of Normalized Cuts. Although we incorporate only the adjacent connections in the multi-layer graph, the foreground object can be efficiently extracted in the spectral framework. The experimental results demonstrate the relevance of our algorithm as compared to existing popular algorithms.

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Finite element analysis of shear critical prestressed SFRC beams

  • Thomas, Job;Ramaswamy, Ananth
    • Computers and Concrete
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    • v.3 no.1
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    • pp.65-77
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    • 2006
  • This study reports the details of the finite element analysis of eleven shear critical partially prestressed concrete T-beams having steel fibers over partial or full depth. Prestressed concrete T-beams having a shear span to depth ratio of 2.65 and 1.59 and failing in the shear have been analyzed using 'ANSYS'. The 'ANSYS' model accounts for the nonlinear phenomenon, such as, bond-slip of longitudinal reinforcements, post-cracking tensile stiffness of the concrete, stress transfer across the cracked blocks of the concrete and load sustenance through the bridging of steel fibers at crack interface. The concrete is modeled using 'SOLID65'-eight-node brick element, which is capable of simulating the cracking and crushing behavior of brittle materials. The reinforcements such as deformed bars, prestressing wires and steel fibers have been modeled discretely using 'LINK8' - 3D spar element. The slip between the reinforcement (rebar, fibers) and the concrete has been modeled using a 'COMBIN39'-non-linear spring element connecting the nodes of the 'LINK8' element representing the reinforcement and nodes of the 'SOLID65' elements representing the concrete. The 'ANSYS' model correctly predicted the diagonal tension failure and shear compression failure of prestressed concrete beams observed in the experiment. The capability of the model to capture the critical crack regions, loads and deflections for various types of shear failures in prestressed concrete beam has been illustrated.

A Network-Based Model for Estimating the Market Share of a High-Speed Rail System in the Korean NW-SE Corridor (네트워크 기반모델을 이용한 서울-부산간 고속철도 개통 후의 교통수단별 시장점유율 예측)

  • Gang-Len Chang
    • Proceedings of the KOR-KST Conference
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    • 2003.02a
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    • pp.127-150
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    • 2003
  • This research presents a novel application of static traffic assignment methods, but with a variable time value, for estimating the market share of a high-speed rail (HSR) in the NW-SE corridor of Korea which is currently served by the airline (AR), conventional rail (CR), and highway (HWY) modes. The proposed model employs the time-space network structure to capture the interrelations among all competing transportation modes, and to reflect their supply- and demand-sides constraints as well as interactions through properly formulated link-node structures. The embedded cost function for each network link offers the flexibility for incorporating all associated factors, such as travel time and fare, in the model computation, and enables the use of a distribution rather than a constant to represent the time-value variation among all transportation mode users. To realistically capture the tripmakers' value-of-time (VOT) along the target area, a novel method for VOT calibration has been developed with aggregate demand information and key system performance data from the target area. Under the assumption that intercity tripmakers often have nearly "perfect" travel information, one can solve the market share of each mode after operations of HSR for each O-D pair under the time-dependent demand with state-of-the-art traffic assignment. Aside from estimating new market share, this paper also investigated the impacts of HSR on other existing transportation modes.

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Cooperation Models and Cooperative Routing for Exploiting Hop-by-Hop Cooperative Diver sity in Ad Hoc Networks

  • Shin, Hee-Wook;Moh, Sang-Man;Chung, Il-Yong
    • Journal of Korea Multimedia Society
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    • v.14 no.12
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    • pp.1559-1571
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    • 2011
  • In wireless ad hoc networks, nodes communicate with each other using multihop routed transmission in which hop-by-hop cooperative diversity can be effectively employed. This paper proposes (i) two cooperation models for per-link cooperation (PLC) and per-node cooperation (PNC) for exploiting cooperative diversity in wireless ad hoc networks and (ii) a cooperative routing algorithm for the above models in which best relays are selected for cooperative transmission. First, two cooperation models for PLC and PNC are introduced and represented as an edge-weighted graph with effective link quality. Then, the proposed models are transformed into a simplified graph and a cooperative routing algorithm with O(n2) time is developed, where n is the number of nodes in the network. The effectiveness of the algorithm is confirmed for the two cooperation models using simulation.

A Physical Ring Design Problem of Synchronous Optical Networks (SONET) for Mass Market Multimedia Telecommunication Services (멀티미디어 서비스를 제공하는 소넷링 불리구조 설계문제)

  • Lee, Young-Ho;Han, Jung-Hee;Kim, Seong-In
    • Journal of Korean Institute of Industrial Engineers
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    • v.24 no.4
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    • pp.571-578
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    • 1998
  • In this paper, we deal with a node weighted Steiner Ring Problem (SRP) arising from the deployment of Synchronous Optical Networks (SONET), a standard of transmission using optical fiber technology. The problem is to find a minimum weight cycle (ring) covering a subset of nodes in the network considering node and link weights. We have developed two mathematical models, one of which is stronger than the other in terms of LP bounds, whereas the number of constraints of the weaker one is polynomially bounded. In order to solve the problem optimally, we have developed some preprocessing rules and valid inequalities. We have also prescribed an effective heuristic procedure for providing tight upper bounds. Computational results show that the stronger model is better in terms of computation time, and valid inequalities and preprocessing rules are effective for solving the problem optimally.

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Wireless Ad-hoc Networks Using Cooperative Diversity-based Routing in Fading Channel

  • Kim, Nam-Soo;An, Beong-Ku;Kim, Do-Hyeon;Lee, Ye-Hoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.2B
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    • pp.69-75
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    • 2008
  • We propose new routing scheme, Cooperative Diversity-based Routing (CDR)which utilize the cooperative space diversity for power saving and for performance enhancement of wireless ad-hoc networks. The end-to-end performance of the proposed routing, CDR, is analyzed based on the Haenggi's link model. The improved performance is compared with Multi-hop Relay Routing (MRR) by analytical methods. When the required outage probability is $1{\times}10^{-3}$ at the destination node in ad-hoc networks with 7 nodes, we noticed that each node can save power consumption by 21.5 dB in average, by using our proposed CDR compared to MRR.

A Study on the Optimal Location of Physical Distribution Centers (중간재고점(中間在庫點) 최적위치선정(最適位置選定)에 관(關)한 연구(硏究))

  • Kim, Man-Sik
    • Journal of Korean Institute of Industrial Engineers
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    • v.1 no.2
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    • pp.39-49
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    • 1975
  • The problem treated is that of locating distribution centers(depot) in a network, so as to minimize the total cost which is the sum of transportation cost, (from factory to centers and from centers to demand points), construction cost, inventory cost and traffic increasing cost. This problem is mathematically an integer program and a non-linear model. This study avoids various inefficient aspects, which many studies have shown, by introducing a matrix notation, node and link function. An algorithm, for determining the optimal location of distribution center which has zone in which demand points are located at some node of a network, is presented. Finally this paper describes a numerical example and discusses its results.

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Study on the Method to Create a Pedestrian Path Using Space Decomposition based on Quadtree (쿼드트리 기반의 공간분할 기법을 활용한 경로 생성 방안에 관한 연구)

  • Ga, Chill-O;Woo, Ho-Seok;Yu, Ki-Yun
    • Spatial Information Research
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    • v.18 no.4
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    • pp.89-98
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    • 2010
  • Recently, the target of navigation system is moving from the cars to pedestrians. Many researches are in progress regarding pedestrian navigation, However, in most cases, the path-finding is based on the existing node/link network model. which is widely used for the car navigation, and thus showing its limitation. The reasons arc that a) unlike with a car, the paths that pedestrians take arc not limited to the roads, b) pedestrians an~ not restricted in rotation or direction, and c) they can freely move within the walkable space. No alternatives have been offered yet, especially for openspaces such as a park or square. Therefore, in this research, we suggested appropriate methods to create paths that can be used in pedestrian navigation service, by using motion-planning technology, which is used in the field of robotics for planning the motion of an object, and conducted tests for their applicability.