• International Journal of Highway Engineering
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• v.11 no.1
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• pp.47-58
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• 2009

Calibrating toll roads of highway networks needs additional weights within volume delay functions not like other general highway lints. However, current methods assigning additional weights in the volume delay function of toll roads are not sufficiently enough to predict real toll road volumes measured, since it does not consider discounting rates and an extra charges. This study develops methods to improve relevant and reliable volume delay functions. Suggested ideas include a method of weighting volume delay functions considering a value of time of vehicle types, a method of weighting volume delay functions considering lane distributions of vehicles, and a method of weighting volume delay functions considering percentages of link lengths per a number of lanes of toll roads. It is found that the method of weighting volume delay functions considering lane distributions of vehicles show most reliable and appropriate results, while the first method shows overestimation and the third method does underestimation of highway link volumes. In terms of assignment methods, total OD equilibrium assignment shows better results than PCU based assignment.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.3
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• pp.13-22
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• 2012

The spatial structure analysis using the existing space syntax has a weakness only to apply the road factor. Hence, it is necessary to perform a new spatial structure analysis considering the regional characteristics factor as well as the road factor. The purpose of this study is to propose a modified spatial structure analysis which adopts road and regional characteristics factors using the existing space syntax and GIS and then to apply it to the spatial structure analysis of the urbanized areas in Hapdeok town. For the new analysis, the experts' survey has been conducted to derive the spatial structure factors of the area and their relative weights. Specifically, it drew the road factor as well as the regional characteristics factors such as road, district, land value, and building density. This study shows that the existing spatial structure analysis considering only the road factor does not reflect the actual spatial structure but the modified spatial structure analysis considering the road factor and the regional characteristics factors more accurately analyzes the spatial structure of Hapdeok town. Hapdeok is not an area where road networks were developed along main development axis and its centrality was changed, but an area where road networks were developed by effectiveness and equity and its centrality was changed by downtown decline. The towns like Hapdeok is more suitable for applying the modified spatial structure analysis method considering the regional characteristics factors. Further research is required for selecting characteristics factors and appropriate parameters in the modified spatial structure analysis. Further case studies await in other cities for conducting its verification.

• Management Science and Financial Engineering
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• v.12 no.2
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• pp.87-110
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• 2006

In a hierarchical road network, all roads can be classified according to their attributes such as speed limit, number of lanes, etc. By splitting the whole road network into the subnetworks of the highlevel and low-level roads, we can reduce the size of the network to be calculated at once, and find a path in the way that drivers usually adopt when searching out a travel route. To exploit the hierarchical property of road networks, we define a convenient path and propose an algorithm for finding convenient paths. We introduce a parameter indicating the driver's tolerance to the difference between the length of a convenient path and that of a shortest convenient path. From this parameter, we can determine how far we have to search for the entering and exiting gateway. We also propose some techniques for reducing the number of pairs of entries and exits to be searched in a road network. A result of the computational experiment on a real road network is given to show the efficiency of the proposed algorithm.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.2
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• pp.7-12
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• 2001

In this paper, an estimation method of hybrid feature was proposed to detect linear feature such as the road network from SAR(synthetics aperture radar) images that include speckle noise. First we considered the mean intensity ratio or the statistical properties of locality neighboring regions to detect linear feature of road. The responses of both methods are combined to detect the entire road network. The purpose of this paper is to extract the segments of road and to mutually connect them according to the identical intensity road from the locally detected fusing images. The algorithm proposed in this paper is to define MRF(markov random field) model of the priori knowledge on the roads and applied it to energy function of interacting density points, and to detect the road networks by optimizing the energy function.

• Journal of Sensor Science and Technology
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• v.26 no.1
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• pp.1-6
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• 2017

The advanced driver assistant system (ADAS) requires the collection of a large amount of information including road conditions, environment, vehicle status, condition of the driver, and other useful data. In this regard, large-scale sensor networks can be an appropriate solution since they have been designed for this purpose. Recent advances in sensor network technology have enabled the management and monitoring of large-scale tasks such as the monitoring of road surface temperature on a highway. In this paper, we consider the estimation and fusion problems of the large-scale sensor networks used in the ADAS. Hierarchical fusion architecture is proposed for an arbitrary topology of the large-scale sensor network. A robust cluster estimator is proposed to achieve robustness of the network against outliers or failure of sensors. Lastly, a robust hierarchical data fusion scheme is proposed for the communication channel between the clusters and fusion center, considering the non-Gaussian channel noise, which is typical in communication systems.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06d
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• pp.190-195
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• 2010

Vehicular ad hoc networks (VANETs) have a number of interesting applications to preserve road safety, notify users about changed road/traffic condition, handling post accident hazards and moreover service oriented applications to make the travel convenient to the drivers. Use of common information format for diverse applications enables the application developers to easily design flexible information dissemination system for new applications or add new features to existing application. This paper introduces a common information format for various applications in VANETs. The main goal of the paper is to design generalized distributed architectures for vehicular networks, which considers diverse application development scenarios and uses common information format. The proposed architectures enable the application developers to flexibly disseminate information to affected or interested user. In this paper, we have given a detail description of each component of the architectures and how they communicate with each other. In future, we will implement the proposed architecture using suitable simulator.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3100-3116
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• 2016

With the rapid development of urban traffic system and fast increasing of vehicle numbers, the traditional centralized ways to generate the source-destination shortest path in terms of travel time(the optimal path) encounter several problems, such as high server pressure, low query efficiency, roads state without in-time updating. With the widespread use of smart cameras in the urban traffic and surveillance system, this paper maps the optimal path finding problem in the dynamic road network to the shortest routing problem in the smart camera networks. The proposed distributed optimal path generation algorithm employs the delay routing and caching mechanism. Real-time route update is also presented to adapt to the dynamic road network. The test result shows that this algorithm has advantages in both query time and query packet numbers.

• Journal of Korean Society of Forest Science
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• v.102 no.1
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• pp.143-155
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• 2013

In order to establish efficient timber harvesting system and provide the necessary data for the system establishment, the techniques to identify areas possible of the yarding-operation and design forest-road networks were newly developed and the applicability of the techniques are tested in this study. The new techniques were developed based on ArcGIS, particularly with utilizing the Viewshed Analysis Tool. From the results of the identification of the possible yarding-operation areas, it is found that the percentage of possible yardingoperation area decreases with the increment of maximum yarding distance due to terrestrial effects. When forest road networks are extended in impossible yarding-operation sites, the area of possible yarding-operation sites increases. If a forest road network is newly designed, its overall extension is altered, resulting in changes in the possible yarding-operation areas. Through the comparative analysis among the different possible yardingoperation areas from different forest road networks, the maximization of the yarding-operation possible area can be achieved. The results from this study can be utilized for establishing more efficient timber-harvesting system and developing GIS-based programs to manage the system.

• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.4
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• pp.243-253
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• 2010

Multihop data delivery in vehicular ad hoc networks (VANETs) suffers from the fact that vehicles are highly mobile and inter-vehicle links are frequently disconnected. In such networks, for efficient multihop routing of road safety information (e.g. road accident and emergency message) to the area of interest, reliable communication and fast delivery with minimum delay are mandatory. In this paper, we propose a multihop vehicle-to-infrastructure routing protocol named Vertex-Based Predictive Greedy Routing (VPGR), which predicts a sequence of valid vertices (or junctions) from a source vehicle to fixed infrastructure (or a roadside unit) in the area of interest and, then, forwards data to the fixed infrastructure through the sequence of vertices in urban environments. The well known predictive directional greedy routing mechanism is used for data forwarding phase in VPGR. The proposed VPGR leverages the geographic position, velocity, direction and acceleration of vehicles for both the calculation of a sequence of valid vertices and the predictive directional greedy routing. Simulation results show significant performance improvement compared to conventional routing protocols in terms of packet delivery ratio, end-to-end delay and routing overhead.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.223-224
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• 2021

Recently, k-farthest neighbor (kFN) queries have not as much attention as k-nearest neighbor (kNN) queries. Therefore, this study considers moving k-farthest neighbor (MkFN) queries for spatial network databases. Given a positive integer k, a moving query point q, and a set of data points P, MkFN queries can constantly retrieve k data points that are farthest from the query point q. The challenge with processing MkFN queries in spatial networks is to avoid unnecessary or superfluous distance calculations between the query and associated data points. This study proposes a batch processing algorithm, called MOFA, to enable efficient processing of MkFN queries in spatial networks. MOFA aims to avoid dispensable distance computations based on the clustering of both query and data points. Moreover, a time complexity analysis is presented to clarify the effect of the clustering method on the query processing time. Extensive experiments using real-world roadmaps demonstrated the efficiency and scalability of the MOFA when compared with a conventional solution.