• Communications for Statistical Applications and Methods
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• v.8 no.1
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• pp.271-279
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• 2001

Sequential pattern discovery is one of main interests in web usage mining. the technique of sequential pattern discovery attempts to find inter-session patterns such that the presence of a set of items is followed by another item in a time-ordered set of server sessions. In this paper, a tree-based sequential pattern finding method is proposed in order to discover navigation patterns in server sessions. At each learning process, the suggested method learns about the navigation patterns per server session and summarized into the modified Rymon's tree.

• Journal of Advanced Navigation Technology
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• v.13 no.5
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• pp.669-676
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• 2009

HTTP or audio/video streaming services are good candidates for future centralized navigation system and in order to provide stability for such services, service providers use a cluster of web servers. In this paper, we provide the criteria for web server cluster design of vehicular users with consideration of differentiated access per different user classes. Several feasible scenarios are examined and their performance analysis using queueing theory is presented to provide the foundation for web server cluster design using traffic load balancer. Through the thorough analysis, efficient criteria for traffic load balancer design is derived. In order to satisfy users' service requirements, priority services controlled by traffic load balancer are considered and analyzed. We also provide the evaluation of the accuracy of the analytical model through simulation.

• Journal of Navigation and Port Research
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• v.43 no.5
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• pp.289-295
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• 2019

In this paper, we implemented a safety navigation mobile application that converged AtoN information and location-based services. When application user uses the smartphone's GPS sensor to transmit the user's vessel location data to the data server, the user receives information of which its providing range is considered, such as stored AtoN data, neighboring vessels information, danger area, and weather information in the server. Providing information is sorted based on the smartphone's direction and inclination and it will be also delivered via wireless network (5G, LTE, 3G, WiFi). Additionally the application is available to implement other functions such as information provision through voice and text alarming service when the user's vessel is either approaching or entering the danger area, and an expanded information provision service that is available in shadow area linking with data-storing methods; other linkable data such as weather and other neighboring vessels will be applied based on the lasted-saved data perceived from the non-shadow area.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.737-740
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• 2001

We develope the PC based SPS to improve safety at sea, save fuel and time during a voyage and makes mariner's work more efficient and comfortable in ship navigation, who propose the auto-navigation system with SPS as basic main system. Developed SPS operate the function to monitor navigational equipment and to substitute a broken main navigational equipment such as CIS, ECDIS, or Radar/ARPA, automatically. These can be improve more efficient and comfortable ship navigation and reduce these traffic accident. The SPS has the function as DB and network server, additionally.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.241-246
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• 2006

The paper presents the preparations work and experiences gained from realtime GPS car monitoring during the European Rally Championships organized on 10-12 June 2005 in Poland. The developed system is based on GPS and GSM/GPRS technology. Distribution and teletransmission of data are possible using different GSM operators in Poland, which makes the system fully independent. The system's server collects data from rally cars, processing and send data through VPN connections to the SQL server located in main control room. Data can be collected in real time via Internet or GPRS. Some information on GSM/GPRS range during rally championships are also presented in the paper. The study covered many trials and tests of different software and various configurations of the GPRS modems before finally the system started to work. Information coming from 10 Rally Cars were collected to the SQL Server continuously in one second interval. In real time mode these all data were displayed simultaneously in the rally main control room and in the rally press conference room. Paper describes also adopted emergency procedures and remote reconfiguration of GPS/GPRS boxes inside rally cars made during championships. Some problems and method of practical solutions are presented to avoid active jamming dangerous for a driver and his pilot, having system of communication intercoms jammed by teletransmission of GPRS 900/1800 MHz. In cooperation with rally teams special GPS/GPRS safety boxes were designed and made. Monitoring of all 7 rally stages with GPS receivers and method of calibrations of the maps were presented. GSM signal coverage was also checked in all stages. All data transmitted from rally cars were recorded in the computer. Some of our GPS cars had accidents and dispite them information were continuously sent to server. There is possibility to show in post mission mode the position of chosen cars in our rally application. Some information of best rally cars are presented also in the paper.

• Journal of Navigation and Port Research
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• v.35 no.9
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• pp.735-740
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• 2011

It is necessary to develop the one stop system in order to protect our marine environment rapidly from oil spill accident. The purpose of this study is to develop real time database for oil spill prediction modeling and implement real time prediction modelling with ESI and server-client GIS based user interface. The existing oil spill prediction model cannot provide one stop information system for public and government who should protect sea from oil spill accident. The development of multi user based information system permits integrated handling of real time meteorological data from external ftp. A server-client GIS based model is integrated on the basis of real time database and ESI map to provide the result of the oil spill prediction model. End users can access through the client interface and request analysis such as oil spill prediction and GIS functions on the network as their own purpose.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.268-271
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• 2004

Today, the vehicle is used the mean of transportation as well as the mobile office with the third digital life space. So telematics is an emerging industry that has tremendous future potential. It is necessary the essential contents for telematics services : navigation map for navigation, POI, real-time traffic information etc. In this paper, we proposed the telematics contents server to manage the telematics contents with efficient performance in distributed environment. The telematics contents server transforms and stores the essential contents and provide it to user through standard interface. The telematics contents server is middleware to offer a rapid essential telematics contents management, client connectivity, and communications. It is useful for the telematics service provider to build telematics system under distributed environment.

• Journal of the Korean Institute of Navigation
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• v.24 no.1
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• pp.47-56
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• 2000

As a shipboard dependency for the safety and reliability becomes very important, the need for solid systems providing non-stop workload has been increased. This system is heartbeat that transmits shipboard state, audit and control information to the land. So, this paper describes a ship's LAN configuration method for the safety and reliability. In order to achieve these requirements, network, server and disk fault tolerance techniques are surveyed, and dual network configuration model, cluster server configuration method are presented and tested based on the survey.

• Journal of Advanced Navigation Technology
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• v.19 no.2
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• pp.161-167
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• 2015

This paper proposed system for providing the national competency standards learning module, which has changed and updated from time to time. The provisioning server of the proposed system provides learning module, and the management server carry out fault management, billing, request management, statistics and aggregate, etc, and the target server requests the learning module in the provisioning server through the domain. The proposed system determines provide of the learning module by CORS based on filter, which is to determine whether matches or not with domain of the provisioning server and the target server. The proposed system can be patch and maintenance remotely about NCS based learning module to be new update and removed. Also, the proposed system may provide contents in conjunction with existing educational systems, and may be extended in the future to enable the management for domain of the target server.

• Journal of Korea Spatial Information System Society
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• v.10 no.2
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• pp.35-48
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• 2008

In this paper, we propose a Dynamic Heuristic to reduce the number of node accesses and improve quality of path in the client-based navigation service. The Dynamic Heuristic is to use heuristic data from server that is calculated with traffic data. The server-based navigation service provides a path searched on server and transmits it to client, but we propose that server only provide heuristic data to client. The proposed client searches a path with heuristic transmitted data from server. We present a new algorithm for using Dynamic Heuristic in the path-finding. The algorithm bases Grid Based Path-Finding, and has minimum speed data of edges in grid. It removes several grids whose minimum speed is less than limited speed.