• Journal of Korean Society of Transportation
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• v.22 no.5
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• pp.123-137
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• 2004

The study on traffic assignment is actively being performed which reflect networks status using time. Its background is increasing social needs to use traffic assignment models in not only hardware area of road network plan but also software area of traffic management or control. In addition, multi-class traffic assignment model is receiving study in order to fill a gap between theory and practice of traffic assignment model. This model is made up of two, one of which is multi-driver class and the other multi-vehicle class. The latter is the more realistic because it can be combined with dynamic model. On this background, this study is to build multidynamic model combining the above-mentioned two areas. This has been a theoretic pillar of ITS in which dynamic user equilibrium assignment model is now made an issue, therefore more realistic dynamic model is expected to be built by combining it with multi-class model. In case of multi-vehicle, FIFO would be violated which is necessary to build the dynamic assignment model. This means that it is impossible to build multi-vehicle dynamic model with the existing dynamic assignment modelling method built under the conditions of FIFO. This study builds dynamic network model which could relieve the FIFO conditions. At the same time, simulation method, one of the existing network loading method, is modified to be applied to this study. Also, as a solution(algorithm) area, time dependent shortest path algorithm which has been modified from existing shortest path algorithm and the existing MSA modified algorithm are built. The convergence of the algorithm is examined which is built by calculating dynamic user equilibrium solution adopting the model and algorithm and grid network.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.1
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• pp.69-75
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• 2020

This paper introduces the parking guide service developed to address the inconvenience of parking in areas where demand for parking spaces is high, such as busy streets and tourist attractions. Due to difficulties in measuring and developing the actual parking lot while driving the car, we created a temporary parking lot and created Arduino RC Car to replace the actual car. Video processing based on Open CV allows users to identify the entire parking lot, parking space, and completed parking space, and track moving cars, and this information has been developed to enable users to see through the application. The application allows the user to book the desired parking space and introduce a way-finding algorithm to guide them through the optimal path to the selected parking compartment.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.4
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• pp.441-448
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• 2012

This paper describes the optimal home positioning algorithm of Eclipse-II, a new conceptual parallel mechanism for motion simulator. Eclipse-II is capable of translation and 360 degrees continuous rotation in all directions. In unexpected situations such as emergency stop, riders have to be resituated as soon as possible through a shortest translational and rotational path because the return paths are not unique in view of inverse kinematic solution. Eclipse-II is man riding. Therefore, the home positioning is directly related to the safety of riders. To ensure a least elapsed time, ZYX Euler angle inverse kinematics is applied to find an optimal home orientation. In addition, the subsequent decrease of maximum acceleration and jerk values is achieved by combining the optimal return path function with cubic spline, which consequently reduces delivery force and vibration to riders.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.6 s.336
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• pp.41-52
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• 2005

In wireless networks there are various errors, caused by multi-path fading and interference between devices which lower the network Performance. Especially, performance of IEEE 802.IS.3 High-Rate WPAN (Wireless Personal Area Network) which is operated in ISM unlicensed frequency band is easily affected by channel errors. In this paper, we propose a scheduling algorithm which takes channel errors into consideration in scheduling asynchronous data traffic. The proposed scheduling algorithm can allocate CTA(Channel Time Allocation) proportionally in accordance with the requested channel time of each device. It also prevents waste of channel time by allocating CTA of the channel-error devices to other channel-error free devices. After recovering from the channel error, the devices are compensated as much as they conceded during channel error status. Simulation results show that the proposed scheduling algorithm is superior to the existing SRPT(Shortest Remain Processing Time) and RR(Round Robin) in throughput and fairness aspects.

• Journal of the Korea Society of Computer and Information
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• v.10 no.1 s.33
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• pp.181-188
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• 2005

Chinese Postman Problem (CPP) is a problem that finds a shortest tour traversing all edges or arcs at least once in a given network. The Chinese Postman Problem on Mixed networks (MCPP) is a Practical generalization of the classical CPP and it has many real-world applications. The MCPP has been shown to be NP-complete. In this paper, we transform a mixed network into a symmetric network using virtual arcs that are shortest paths by Floyd's algorithm. With the transformed network, we propose a Genetic Algorithm (GA) that converges to a near optimal solution quickly by a multi-directional search technique. We study the chromosome structure used in the GA and it consists of a path string and an encoding string. An encoding method, a decoding method, and some genetic operators that are needed when the MCPP is solved using the Proposed GA are studied. . In addition, two scaling methods are used in proposed GA. We compare the performance of the GA with an existing Modified MDXED2 algorithm (Pearn et al. , 1995) In the simulation results, the proposed method is better than the existing methods in case the network has many edges, the Power Law scaling method is better than the Logarithmic scaling method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.494-497
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• 2022

Recently, the damage caused by flash floods caused by extreme weather due to global warming is increasing. In order to reduce the damage, this paper conducted a study on the search for the shortest route of an evacuation route due to a flash flood. For this, we implemented a route search system using GIS and shape files including buildings and roads and Dijkstra's algorithm. In this study, the location of users close to the point where the flash flood occurs is identified, and the evacuation route is searched from the starting point to the destination point without passing through the dangerous point. Evacuate out of the test bed, or designate a building in the test bed as an evacuation shelter, and search for a route to the nearest evacuation shelter. Accordingly, it is expected that human damage will be reduced by providing the shortest evacuation route.

• The Journal of Korea Robotics Society
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• v.18 no.1
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• pp.1-9
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• 2023

This paper presents an optimal path planning strategy for aerial searching and surveying of a user-designated area using multiple Unmanned Aerial Vehicles (UAVs). The method is designed to deal with a single unseparated polygonal area, regardless of polygonal convexity. By defining the search area into a set of grids, the algorithm enables UAVs to completely search without leaving unsearched space. The presented strategy consists of two main algorithmic steps: cellular decomposition and path planning stages. The cellular decomposition method divides the area to designate a conflict-free subsearch-space to an individual UAV, while accounting the assigned flight velocity, take-off and landing positions. Then, the path planning strategy forms paths based on every point located in end of each grid row. The first waypoint is chosen as the closest point from the vehicle-starting position, and it recursively updates the nearest endpoint set to generate the shortest path. The path planning policy produces four path candidates by alternating the starting point (left or right edge), and the travel direction (vertical or horizontal). The optimal-selection policy is enforced to maximize the search efficiency, which is time dependent; the policy imposes the total path-length and turning number criteria per candidate. The results demonstrate that the proposed cellular decomposition method improves the search-time efficiency. In addition, the candidate selection enhances the algorithmic efficacy toward further mission time-duration reduction. The method shows robustness against both convex and non-convex shaped search area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.740-745
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• 2016

Cables are installed for tens of thousands of connections between various pieces of equipment to operate and control a commercial ship. The correct shortest-route data is necessary since these are complicated cable installations. Therefore, an overfill interval commonly exists in the shortest paths for cables as estimated by Dijkstra's algorithm, even if this algorithm is generally used. It is difficult for an electrical engineer to find the overfill interval in 3D cable models because the occupancy rate data exist in a data sheet unlinked to three-dimensional (3D) computer-aided design (CAD). The purpose of this study is to suggest a visualization method that displays the cable path and overfill interval in 3D CAD. This method also provides various color visualizations for different overfill ranges to easily determine the overfill interval. This method can reduce cable-installation man-hours from 7,000 to 5,600 thanks to a decreased re-installation rate, because the cable length calculation's accuracy is raised through fast and accurate reviews based on 3D cable visualization. As a result, material costs can also be reduced.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.3
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• pp.1-14
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• 2008

Mass transit information should contribute many benefits to users. Especially transportation information technology is developing highly with information technology in Korea recently. Hereafter it is expected to provide customized transportation information to users individually with the advent of ubiquitous age in earnest. This public transportation information service can be realized by path finding algorithms in public transportation networks including travel and transfer attributes. In this research, multi objectives such as travel time, transfer time, and number of transfer and so on are constructed with the primary facts influencing users. Moreover, the method reducing user's path finding alternatives arbitrarily is proposed by selecting the best alternative which provides maximum utility to users among non dominated paths. Therefore, the ultimate goal of this study proposes a multi objective shortest paths finding algorithm which can take into account multiple user classes in a transit network with multiple travel modes. The proposed algorithm is demonstrated based on the two case studies - a small toy network and the large-scaled Seoul Metropolitan subway network.

• Journal of Korea Multimedia Society
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• v.22 no.12
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• pp.1466-1480
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• 2019

This paper addresses the efficient processing of all-farthest-neighbors (AFN) queries in spatial network databases. Given a set of data points P={p₁,p₂,…,p_|p|} in a spatial network, where the distance between two data points p and s, denoted by dist (p,s), is the length of the shortest path between them, an AFN query is defined as follows: find the farthest neighbor ω(p)∈P of each data point p such that dist(p,ω(p)) ≥ dist(p,s) for all s∈P. In this paper, we propose a shared execution algorithm called FAST (for All-Farthest-neighbors Search in spatial neTworks). Extensive experiments on real-world roadmaps confirm the efficiency and scalability of the FAST algorithm, while demonstrating a speedup of up to two orders of magnitude over a conventional solution.