• Title/Summary/Keyword: Shortest Path Algorithm

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Design and Implementation of Indoor Positioning & Shortest Path Navigation System Using GPS and Beacons in Narrow Buildings

  • Sang-Hyeon, Park;Huhnkuk, Lim
    • Journal of the Korea Society of Computer and Information
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    • v.28 no.3
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    • pp.11-16
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    • 2023
  • As techniques for indoor positioning, fingerprinting, indoor positioning method using trilateration, and utilizing information obtained from equipments by Wi-Fi/Bluetooth, etc are common and representative methods to specify the user's indoor position. However, in these methods, an indoor space should be provided with enough space to install a large number of equipment (AP, Beacon). In this paper, we propose a technique that can express the user's location within a building by simultaneously using the GPS signal and the signal transmitted from the beacon in a building structure where the conventional method cannot be applied, such as a narrow building. A shortest path search system was designed and implemented by applying the Dijkstra Algorithm, one of the most representative and efficient shortest path search algorithms for shortest path search. The proposed technique can be considered as one of the methods for measuring the user's indoor location considering the structural characteristics of a building in the future.

Comparision and Analysis of Algorithm for web Sites Researching (웹 사이트 탐색 알고리즘 비교분석)

  • 김덕수;권영직
    • Journal of Korea Society of Industrial Information Systems
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    • v.8 no.3
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    • pp.91-98
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    • 2003
  • Visitors who browse the web from wireless PDAs, cell phones are frequently frustrated by interfaces. Simply replacing graphics with text and reformatting tables does not solve this problem, because deep link structures can still require more time. To solve this problem, in the paper we propose an algorithm, Minimal Path Algorithm that automatically improves wireless web navigation by suggesting useful shortcut links in real time. In the result of this paper, Minimal Path algorithm offer the shortcut and the number of shortest links to web users.

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Path Planning for the Shortest Driving Time Considering UGV Driving Characteristic and Driving Time and Its Driving Algorithm (무인 주행 차량의 주행 특성과 주행 시간을 고려한 경로 생성 및 주행 알고리즘)

  • Noh, Chi-Beom;Kim, Min-Ho;Lee, Min-Cheol
    • The Journal of Korea Robotics Society
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    • v.8 no.1
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    • pp.43-50
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    • 2013
  • $A^*$ algorithm is a global path generation algorithm, and typically create a path using only the distance information. Therefore along the path, a moving vehicle is usually not be considered by driving characteristics. Deceleration at the corner is one of the driving characteristics of the vehicle. In this paper, considering this characteristic, a new evaluation function based path algorithm is proposed to decrease the number of driving path corner, in order to reduce the driving cost, such as driving time, fuel consumption and so on. Also the potential field method is applied for driving of UGV, which is robust against static and dynamic obstacle environment during following the generated path of the mobile robot under. The driving time and path following test was occurred by experiments based on a pseudo UGV, mobile robot in downscaled UGV's maximum and driving speed in corner. The experiment results were confirmed that the driving time by the proposed algorithm was decreased comparing with the results from $A^*$ algorithm.

Goal-Directed Reinforcement Learning System (목표지향적 강화학습 시스템)

  • Lee, Chang-Hoon
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.5
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    • pp.265-270
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    • 2010
  • Reinforcement learning performs learning through interacting with trial-and-error in dynamic environment. Therefore, in dynamic environment, reinforcement learning method like TD-learning and TD(${\lambda}$)-learning are faster in learning than the conventional stochastic learning method. However, because many of the proposed reinforcement learning algorithms are given the reinforcement value only when the learning agent has reached its goal state, most of the reinforcement algorithms converge to the optimal solution too slowly. In this paper, we present GDRLS algorithm for finding the shortest path faster in a maze environment. GDRLS is select the candidate states that can guide the shortest path in maze environment, and learn only the candidate states to find the shortest path. Through experiments, we can see that GDRLS can search the shortest path faster than TD-learning and TD(${\lambda}$)-learning in maze environment.

Intelligent Optimal Route Planning Based on Context Awareness (상황인식 기반 지능형 최적 경로계획)

  • Lee, Hyun-Jung;Chang, Yong-Sik
    • Asia pacific journal of information systems
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    • v.19 no.2
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    • pp.117-137
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    • 2009
  • Recently, intelligent traffic information systems have enabled people to forecast traffic conditions before hitting the road. These convenient systems operate on the basis of data reflecting current road and traffic conditions as well as distance-based data between locations. Thanks to the rapid development of ubiquitous computing, tremendous context data have become readily available making vehicle route planning easier than ever. Previous research in relation to optimization of vehicle route planning merely focused on finding the optimal distance between locations. Contexts reflecting the road and traffic conditions were then not seriously treated as a way to resolve the optimal routing problems based on distance-based route planning, because this kind of information does not have much significant impact on traffic routing until a a complex traffic situation arises. Further, it was also not easy to take into full account the traffic contexts for resolving optimal routing problems because predicting the dynamic traffic situations was regarded a daunting task. However, with rapid increase in traffic complexity the importance of developing contexts reflecting data related to moving costs has emerged. Hence, this research proposes a framework designed to resolve an optimal route planning problem by taking full account of additional moving cost such as road traffic cost and weather cost, among others. Recent technological development particularly in the ubiquitous computing environment has facilitated the collection of such data. This framework is based on the contexts of time, traffic, and environment, which addresses the following issues. First, we clarify and classify the diverse contexts that affect a vehicle's velocity and estimates the optimization of moving cost based on dynamic programming that accounts for the context cost according to the variance of contexts. Second, the velocity reduction rate is applied to find the optimal route (shortest path) using the context data on the current traffic condition. The velocity reduction rate infers to the degree of possible velocity including moving vehicles' considerable road and traffic contexts, indicating the statistical or experimental data. Knowledge generated in this papercan be referenced by several organizations which deal with road and traffic data. Third, in experimentation, we evaluate the effectiveness of the proposed context-based optimal route (shortest path) between locations by comparing it to the previously used distance-based shortest path. A vehicles' optimal route might change due to its diverse velocity caused by unexpected but potential dynamic situations depending on the road condition. This study includes such context variables as 'road congestion', 'work', 'accident', and 'weather' which can alter the traffic condition. The contexts can affect moving vehicle's velocity on the road. Since these context variables except for 'weather' are related to road conditions, relevant data were provided by the Korea Expressway Corporation. The 'weather'-related data were attained from the Korea Meteorological Administration. The aware contexts are classified contexts causing reduction of vehicles' velocity which determines the velocity reduction rate. To find the optimal route (shortest path), we introduced the velocity reduction rate in the context for calculating a vehicle's velocity reflecting composite contexts when one event synchronizes with another. We then proposed a context-based optimal route (shortest path) algorithm based on the dynamic programming. The algorithm is composed of three steps. In the first initialization step, departure and destination locations are given, and the path step is initialized as 0. In the second step, moving costs including composite contexts into account between locations on path are estimated using the velocity reduction rate by context as increasing path steps. In the third step, the optimal route (shortest path) is retrieved through back-tracking. In the provided research model, we designed a framework to account for context awareness, moving cost estimation (taking both composite and single contexts into account), and optimal route (shortest path) algorithm (based on dynamic programming). Through illustrative experimentation using the Wilcoxon signed rank test, we proved that context-based route planning is much more effective than distance-based route planning., In addition, we found that the optimal solution (shortest paths) through the distance-based route planning might not be optimized in real situation because road condition is very dynamic and unpredictable while affecting most vehicles' moving costs. For further study, while more information is needed for a more accurate estimation of moving vehicles' costs, this study still stands viable in the applications to reduce moving costs by effective route planning. For instance, it could be applied to deliverers' decision making to enhance their decision satisfaction when they meet unpredictable dynamic situations in moving vehicles on the road. Overall, we conclude that taking into account the contexts as a part of costs is a meaningful and sensible approach to in resolving the optimal route problem.

Complete Time Algorithm for Stadium Construction Scheduling Problem

  • Lee, Sang-Un
    • Journal of the Korea Society of Computer and Information
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    • v.20 no.9
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    • pp.81-86
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    • 2015
  • This paper suggests heuristic algorithm with linear time complexity to decide the normal and optimal point at minimum loss/maximum profit maximum shortest scheduling problem with additional loss cost and bonus profit cost. This algorithm computes only the earliest ending time for each node. Therefore, this algorithm can be get the critical path and project duration within O(n) time complexity and reduces the five steps of critical path method to one step. The proposed algorithm can be show the result more visually than linear programming and critical path method. For real experimental data, the proposed algorithm obtains the same solution as linear programming more quickly.

An One-To-One K-Shortest Path Algorithm Considering Vine Travel Pattern (덩굴망 통행패턴을 고려한 One-To-One 다경로알고리즘)

  • Lee, Mee-Young;Yu, Ki-Yun;Kim, Jeong-Hyun;Shin, Seong-Il
    • Journal of Korean Society of Transportation
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    • v.21 no.6
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    • pp.89-99
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    • 2003
  • Considering a path represented by a sequence of link numbers in a network, the vine is differentiated from the loop in a sense that any link number can be appeared in the path only once, while more than once in the loop. The vine provides a proper idea how to account for complicated travel patterns such as U-turn and P-turn witnessed nearby intersections in urban roads. This paper proposes a new algorithm in which the vine travel pattern can be considered for finding K number of sequential paths. The main idea of this paper is achieved by replacing the node label of the existing Yen's algorithm by the link label technique. The case studies show that the algorithm properly represent the vine travel patterns in searching K number of paths. A noticeable result is that the algorithm may be a promising alternative for ITS deployment by enabling to provide reasonable route information including perceived traveler costs.

A Study on Cutting Path Optimization Using Genetic Algorithm (유전자 알고리즘을 이용한 부재 절단 경로 최적화)

  • Park, Ju-Yong;Seo, Jeong-Jin
    • Journal of Ocean Engineering and Technology
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    • v.23 no.6
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    • pp.67-70
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    • 2009
  • Nesting and cutting path optimization have a great effect on the improvement of productivity in many industries such as shipbuilding, automotive, clothing, and so on. However, few researches have been carried out for the optimization of a cutting path algorithm. This study proposed a new method for cutting optimization using gravity center of cutting pieces and a genetic algorithm. The proposed method was tested for a sample plate including many different shapes of cutting pieces and compared to 2 other conventional methods. The test results showed that the new method had the shortest cutting path and the best effectiveness among the 3 methods.

A Possible Path per Link CBR Algorithm for Interference Avoidance in MPLS Networks

  • Sa-Ngiamsak, Wisitsak;Varakulsiripunth, Ruttikorn
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.772-776
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    • 2004
  • This paper proposes an interference avoidance approach for Constraint-Based Routing (CBR) algorithm in the Multi-Protocol Label Switching (MPLS) network. The MPLS network itself has a capability of integrating among any layer-3 protocols and any layer-2 protocols of the OSI model. It is based on the label switching technology, which is fast and flexible switching technique using pre-defined Label Switching Paths (LSPs). The MPLS network is a solution for the Traffic Engineering(TE), Quality of Service (QoS), Virtual Private Network (VPN), and Constraint-Based Routing (CBR) issues. According to the MPLS CBR, routing performance requirements are capability for on-line routing, high network throughput, high network utilization, high network scalability, fast rerouting performance, low percentage of call-setup request blocking, and low calculation complexity. There are many previously proposed algorithms such as minimum hop (MH) algorithm, widest shortest path (WSP) algorithm, and minimum interference routing algorithm (MIRA). The MIRA algorithm is currently seemed to be the best solution for the MPLS routing problem in case of selecting a path with minimum interference level. It achieves lower call-setup request blocking, lower interference level, higher network utilization and higher network throughput. However, it suffers from routing calculation complexity which makes it difficult to real task implementation. In this paper, there are three objectives for routing algorithm design, which are minimizing interference levels with other source-destination node pairs, minimizing resource usage by selecting a minimum hop path first, and reducing calculation complexity. The proposed CBR algorithm is based on power factor calculation of total amount of possible path per link and the residual bandwidth in the network. A path with high power factor should be considered as minimum interference path and should be selected for path setup. With the proposed algorithm, all of the three objectives are attained and the approach of selection of a high power factor path could minimize interference level among all source-destination node pairs. The approach of selection of a shortest path from many equal power factor paths approach could minimize the usage of network resource. Then the network has higher resource reservation for future call-setup request. Moreover, the calculation of possible path per link (or interference level indicator) is run only whenever the network topology has been changed. Hence, this approach could reduce routing calculation complexity. The simulation results show that the proposed algorithm has good performance over high network utilization, low call-setup blocking percentage and low routing computation complexity.

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On Finding an Optimal Departure Time in Time-Dependent Networks

  • Park, Chan-Kyoo;Lee, Sangwook;Park, Soondal
    • Management Science and Financial Engineering
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    • v.10 no.1
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    • pp.53-75
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    • 2004
  • Most existing studies on time-dependent networks have been focused on finding a minimum delay path given a departure time at the origin. There, however, frequently happens a situation where users can select any departure time in a certain time interval and want to spend as little time as possible on traveling the networks. In that case. the delay spent on traveling networks depends on not only paths but also the actual departure time at the origin. In this paper, we propose a new problem in time-dependent networks whose objective is to find an optimal departure time given possible departure time interval at the origin. From the optimal departure time, we can obtain a path with minimum delay among all paths for possible departure times at the origin. In addition, we present an algorithm for finding an optimal departure time by enumerating trees which remain shortest path tree for a certain time interval.