• KIISE Transactions on Computing Practices
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• v.20 no.12
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• pp.652-657
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• 2014

Given a starting point, destination point and various Points Of Interest (POIs), which contain a full or partial order, for a user to visit we wish to create, a sequenced route from the starting point to the destination point that includes one member of each POI type in a particular order. This paper proposes a method for finding the approximate shortest route between the start point, destination point and one member of each POI type. There are currently two algorithms that perform this task but they both have weaknesses. One of the algorithms only considers the distance between the visited POI (or starting point) and POI to visit next. The other algorithm chooses candidate points near the straight-line distance between the start point and destination but does not consider the order of visits on the corresponding network path. This paper outlines an algorithm that chooses the candidate points that are nearer to the network path between the start point and destination using network search. The algorithm looks for routes using the candidate points and finds the approximate shortest route by assigning an adaptive priority to the route that visits more POIs in a short amount of time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1581-1589
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• 2013

The aim of this study is to suggest a methodology for calculating the peak-hour ratio of passengers at urban railway stations by reflecting the characteristics of passenger demand patterns and the land use inventory of stations. To achieve this, urban railway stations in Seoul are divided into three groups by using factor analysis and cluster analysis. For each station group, we calculate five and four variables related to the passenger demand patterns and the land use inventory of stations, respectively, as well as the peak-hour ratios of passengers. Among these nine variables, average daily passengers and the location quotient (LQ) index for business services are selected as the classification criteria for station groups based on statistical tests. Using the two variables, a group allocation process is suggested to estimate the peak-hour ratio of passengers for a newly-constructed station. Evaluation results based on thirteen stations show that the proposed methodology produces lower errors than the currently-used guideline does. The results of this study contribute to establishing efficiently construction and operation plans for newly-constructed stations.

• Journal of Korea Water Resources Association
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• v.47 no.12
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• pp.1145-1154
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• 2014

In recent years, as frequency and intensity of severe weather disasters such as flash flood have been increasing, providing accurate and prompt information to the public is very important and needs of user-friendly monitoring/warning system are growing. This paper introduces a method that re-produces radar observations as multimedia contents and applies reproduced data to mesh-up services. In addition, a accurate GIS matching technique to help to track the exact location going on serious atmospheric phenomena is presented. The proposed method create multimedia contents having structures such as two dimensional images, vector graphics or three dimensional volume data by re-producing various radar variables obtained from a weather radar. After then, the multimedia formatted weather radar data are matched with various detailed raster or vector GIS map platform. Results of simulation test with various scenarios indicate that the display system based on the proposed method can support for users to figure out easily and intuitively routes and degrees of risk of severe weather. We expect that this technique can also help for emergency manager to interpret radar observations properly and to forecast meteorological disasters more effectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.31-37
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• 2016

Ranging is divided into a synchronous scheme and an asynchronous scheme according to the presence of global synchronization between nodes. In general, the asynchronous ranging is preferred over synchronous ranging because it does not require an expensive high-precision oscillator for the global synchronization. On the other hand, in a conventional asynchronous ranging scheme, the packets, which are generated by all nodes in a positioning system of a large-scale infrastructure and need to be sent for localization by reference nodes, are considerable, which cause an increase in network traffic as the number of nodes increases. The traffic congestion lowers the throughput of the network leading to a considerable loss of energy. To solve this problem, this paper proposes a ranging scheme, in which virtual transmission slots randomly and discretely selected by a plurality of nodes are used to reduce the overheads needed in synchronizing the nodes, and the ranging is performed asynchronously based on the virtual transmission slots, thereby decreasing the network traffic. In addition, a performance test proved that the proposed ranging scheme was stronger than the TWR and SDS-TWR on an error range, even though the intensity of traffic was very low.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.5
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• pp.546-554
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• 2016

Free-viewpoint video (FVV) is a synthesization technology that generates a virtual viewpoint video using multiple videos recorded via wireless devices at heterogeneous locations. In order to introduce a new service that grafts the FVV onto the real-time streaming service using wireless devices, we need to overcome several constraints. Two main factors of those constraints are the limited wireless capacity that are shared fairly by multiple devices, and the transmission time constraint with which live streaming services have to comply. Therefore, for optimal quality of entire videos, a set of transmitting devices should be effectively selected depending on the condition of wireless channel and the required video popularity of specific viewpoint requested from users. For optimal selection, this study proposes a heuristic algorithm that takes into account the aforementioned factors from possible wireless transmission error behaviors and the requested viewpoint popularity. Through analysis and simulation, we show that with this algorithm, quality of most popular viewpoint videos is guaranteed. Furthermore, performance comparison against the existing scheme which is based only on the location of recording devices is made.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.677-685
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• 2011

In order to enhance public transportation and to maintain information credibility, improvement of accuracy regarding route and positional information of public transport is very significant. There have been a variety of methods using GPS to measure accuracy of location-based services. However, the researches of evaluation regarding kinematic position of linear objects measured by vehicle/kinematic GPS are still insufficient. That's why our paper aims to suggest method of evaluation accuracy on a real-time bus route surveyed by GPS by SBM(Single Buffering Method). To make it come true, we compared the findings on the static and dynamic positioning by using PP(Point Positioning), DGPS and GPS/INS integrated systems and analyzed the accuracy and error effects among them, focusing on Anyang city. Consequently, we can find out that in case of P.P. comparing positioning accuracy between RTK DGPS and GPS/INS, both of them have survey result within a margin of error of 5m. More importantly, we can evaluate positional accuracy of each GPS system based on the work provision of a public survey such as error for P.P.(14.5m, 18.1m), DGPS(16.9m, 18.5m), and GPS/INS(18.4m, 18.5m). We are expecting that proposed method in our paper can be utilized in a wide range of categories such as feasibility testing of GPS field survey and high accuracy of positioning for Bus Information System.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.969-972
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• 2015

Many studies have been carried out in order to develop a frequency efficient communication system than the current communication system for satisfying the increasing demands of wireless data services in mobile communication systems. If a communication system dramatically improving the frequency utilization efficiency is not developed, service providers must maintain more number of base station equipments to meet the increasing demands of wireless data service. Service provider needs a system or method to reduce maintenance costs. Demands of wireless data service are changed according to time of day, location and so on. Power consumption can be reduced if the supplied power of communication systems is controlled by wireless data traffics. This paper describes the design and implementation of power management system of mobile communication base station's equipment based on smart grid. The proposed power management system controls the supplied power to the mobile communication infrastructures depending on the demand of wireless data. Field test results of the implemented system show the proposed system saves 26% of the power consumption in the base stations.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.2
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• pp.50-64
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• 2019

According to the Maritime Safety Act, there are all 34 routes including 5 traffic safety zones, 3 traffic separation schemes, 26 routes designated by regional maritime affairs departments in the Republic of Korea. In the SOLAS convention, the route information should be is effectively used for the safe navigation. However, the route information is complicatedly composed of the location of the route, the navigation rule by each route, the restriction of the navigation, and the anchorages. Moreover, the present method of providing information using the navigational chart and other publications is not effective for users to grasp the navigational information. Therefore, it was conducted to study the design of the S-100 based routing information data model developed by the International Hydrographic Organization to find ways to more effectively provide route information. To do this, the analysis of route requirement, selection of items, encoding test and users' review were carried out. Through expert user review, it was evaluated that the study on the design of the route information data model can be utilized as a good basic data for the route information integration service. Future research on the development of route information data models is expected to provide integrated route information services.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2014.10a
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• pp.25-48
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• 2014

Increased frequency of climate extremes is another face of climate change confronted by humans, resulting in catastrophic losses in agriculture. While climate extremes take place on many scales, impacts are experienced locally and mitigation tools are a function of local conditions. To address this, agrometeorological early warning systems must be place and location based, incorporating the climate, crop and land attributes at the appropriate scale. Existing services often lack site-specific information on adverse weather and countermeasures relevant to farming activities. Warnings on chronic long term effects of adverse weather or combined effects of two or more weather elements are seldom provided, either. This lecture discusses a field-specific early warning system implemented on a catchment scale agrometeorological service, by which volunteer farmers are provided with face-to-face disaster warnings along with relevant countermeasures. The products are based on core techniques such as scaling down of weather information to a field level and the crop specific risk assessment. Likelihood of a disaster is evaluated by the relative position of current risk on the standardized normal distribution from climatological normal year prepared for 840 catchments in South Korea. A validation study has begun with a 4-year plan for implementing an operational service in Seomjin River Basin, which accommodates over 60,000 farms and orchards. Diverse experiences obtained through this study will certainly be useful in planning and developing the nation-wide disaster early warning system for agricultural sector.

• Journal of Internet of Things and Convergence
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• v.6 no.4
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• pp.89-92
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• 2020

According to the various IoT(Internet of Things) services, there have been lots of task offloading researches for IoT devices. Since there are service response delay and core network load issues in conventional cloud computing based offloadings, fog computing based offloading has been focused whose location is close to the IoT devices. However, even in the fog computing architecture, the load can be concentrated on the for computing node when the number of requests increase. To solve this problem, the opportunistic fog computing concept which offloads task to available computing resources such as cars and drones is introduced. In previous fog and opportunistic fog node researches, the offloading is performed immediately whenever the service request occurs. This means that the service requests can be offloaded to the opportunistic fog nodes only while they are available. However, if the service response delay requirement is satisfied, there is no need to offload the request immediately. In addition, the load can be distributed by making the best use of the opportunistic fog nodes. Therefore, this paper proposes a delayed offloading scheme to satisfy the response delay requirements and offload the request to the opportunistic fog nodes as efficiently as possible.