• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.445-450
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• 2018

AIS is the most important navigation equipment for the identification of other ships, etc. However, the AIS overload problem has been raised recently due to an increase in AIS equipped vessels. The government is planning to introduce the wireless LTE network at 100 km offshore as part of the SMART-Navigation project. Continuous development and dissemination of the services available through such platforms will be necessary to achieve major goals such as marine accident prevention and environmental protection. In this study, we applied a WAVE communication system, which could be the basis for the development of such services. As a result, reliable data transmission was confirmed for a range of communication of approx. 5 miles, although the service was limited to 1 km in road traffic. Therefore, it is expected that WAVE communication technology will be used to prevent marine accidents through such efforts as collision avoidance and the transfer of marine safety information between ships.

• Journal of the Korea Society of Computer and Information
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• v.7 no.3
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• pp.80-91
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• 2002

A general goal of the AT%(Asynchronous Transfer Mode) network is to support connect across various network. On ATM networks, ABR services are provided using the remained ban after allocation CBR and VBR traffic. Realtime services such as transmitting audio or video data may be provided using CBR ado VBR which have a constrained transmission delay, but in these cases, the communications bandwidth may be wasted. In this paper a simulation has been performed to compare and evaluate the performance between the ERICA(Explicit Rate Indicate Avoidance) and EPRCA(Enhanced Proportional Rate Control Algorithm) switches which use Explicit Rate switch algorithm for ABR switch. The variation of the ACR at the source end system, the queue length, the utilization rate of the link bandwidth and the share fairness at the transient and steady states are used as the evaluation criteria for the simulation. As a result of simulation, ERICA algorithm switch was ten times long compared to ERPCA switch to achieve assigned fair share. so EPRCA switch is superior to ERICA about load response. For Fair share and stability, ERICA switch is excellent to EPRCA switch.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.9 s.351
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• pp.105-119
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• 2006

The car navigation system to be accompanied to the car on-board equipment system or the development of mobile communication technique, the demand in information communication which connects an interior and the car outside is coming to be high, As applications, ETC/VISC/AHS classes get deceived supply are advanced. The research of DSRC radio systems actively, with medium of communication between the automobile and road, is advanced. DSRC radio systems are appropriate in massive data transfer, in the case which the traffic accident evasion is urgent, the notarization of the preferential control function which is necessary to a medium of communication, guarantee and security are suitable in the high-speed network. Accompanied to the cellular phone which is to be supplied recently suddenly, By complementing and coexisting each other, and it will be developed simultaneously. However, in a connection of this kind of communication system and high-speed DSRC radio system, Hand-over technique (network, radio transmission hand-over), there is a technical subject of the high-speed transmission techniques against the mobile devices and the realization is expected to be difficult in near, until 2010 year is becoming the plan of putting to practical use. Also as the next generation DSRC with 5.8GHz built-on board equipment and the road-side equipment are expected in near. In this paper DSRC systems which will be developed are discussed.

• International Journal of Highway Engineering
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• v.13 no.3
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• pp.21-30
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• 2011

As well known, dowel bars are used to transfer traffic load acting on one edge to another edge of concrete slab in concrete pavement system. The dowel bars widely used in South Korea are round shape steel bar and they shows satisfactory performance under bending stress which is developed by repetitive traffic loading and environment loading. However, they are not invulnerable to erosion that may be caused by moisture from masonry joint or bottom of the pavement system. Especially, the erosion could rapidly progress with saline to prevent frost of snow in winter time. The problem under this circumstance is that the erosion not only drops strength of the steel dower bar but also comes with volume expansion of the steel dowel bar which can reduce load transferring efficiency of the steel dowel bar. To avoid this erosion problem in reasonable expenses, dowers bars with various materials are being developed. Fiber reinforced plastic(FRP) dower that is presented in this paper is suggested as an alternative of the steel dowel bar and it shows competitive resistance against erosion and tensile stress. The FRP dowel bar is developed in tube shape and is filled with high strength no shrinkage. Several slab thickness designs with the FRP dowel bars are performed by evaluating bearing stress between the dowel bar and concrete slab. To calculated the bearing stresses, theoretical formulation and finite element method(FEM) are utilized with material properties measured from laboratory tests. The results show that both FRP tube dowel bars with diameters of 32mm and 40mm satisfy bearing stress requirement for dowel bars. Also, with consideration that lean concrete is typical material to support concrete slab in South Korea, which means low load transfer efficiency and, therefore, low bearing stress, the FRP tube dowel bar can be used as a replacement of round shape steel bar.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.2
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• pp.84-93
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• 2011

In order to provide the real time and proper information to the pedestrian who is using the transport connection and transfer center through data collecting and processing process, the design of the test-bed (Gimpo airport)'s communication construction and the technology of the pedestrian location tracking has been researched. The design of the communication construction should make sure that it can provide believable data to the user of the transfer center. At the same time, the location tracking should also be considered, so that the require of the communication efficiency and the location tracking efficiency can be met together. In order to make the efficient location tracking technology, the problems related to the commercial technology based real time location identification will be resolved and the new approach method was proposed and be applied and analysed to the test-bed. The wireless access points can be located in the most real-world situation which has added the characteristics of the real building to the electronic map, and through the analysis of theirs location, they can be set as the mainly necessary points for the communication construction design and the location tracking and the method to locate that points has been proposed. How to set, how to apply it to the test-bed and the examination result will be introduced in this paper.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.497-500
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• 2010

Wireless sensor network is the system for data collection and data process between many nodes. For this work, Synchronization of operation execution and ordering many events are needed. Reference the external time information is the most accurate way to have same time information for all nodes but it's hard to apply these to sensor network. So there are many study of time synchronization there are many error occurred when the time synchronization is executed in the sensor network and minimizing these errors is important. In this paper, we propose how to minimize errors using several time stamp information exchanging when the network is initialized. When the big difference is occurred between receive time and send time in the node communication(cause of traffic overhead and etc), it shows big error of time correction and transfer delay time. but it's hard to detect these errors when it exchanges time stamp information just one time. so we try to reduce these errors using the median value of transfer delay and time correction value with many times of time stamp information exchange.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.1-11
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• 2007

Seoul's transportation system was changed drastically starting the first of June in two thousand. This policy includes integrated distance-based fare system and public transportation card system called smart card. Especially, as public transportation card data contains individual travel, transfer and using modes information it is possible to catch the characteristics of path-based individuals and mass transit. Thus, public transportation card data can contribute to evaluate the mass transit service in integrated public transportation networks. In addition, public transportation card data are able to help to convert previous researches and analyses with link-based trip assignment models to path-based mass transit service analysis. In this study, an algorithm being suitable for path-based trip assignment models is suggested and proposed algorithm can also contribute to make full use of public transportation card data. For this, column generation algorithm hewn to draw the stable solution is adopted. This paper uses the methodology that is to take local approximate equilibrium from partial network and expand local approximate equilibrium to global equilibrium.

• Land and Housing Review
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• v.8 no.4
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• pp.285-294
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• 2017

Recently, as the paradigm of regional development has been transformed into characterization, decentralization and cooperation, small and medium scale development is in the spotlight. In particular, as the transfer of planning authority to local governments accelerates, LH is in the process of seeking to transform itself into a system that is in line with local government demand. The purpose of this study is to elaborate the regional pending projects that meet the demand of the region. The Jeju Special Self-Governing Province is the area where land and housing prices have increased more than three times recently, which is the area of interest in recent years due to the various demand for development projects. Another objective is to establish a local government based on LH's system, it is aimed to derive a collaboration method with local government, province corporation and local researchers. The criteria for deriving the cooperation projects between the local government and LH are basically the ones that can be carried out by LH and future-oriented projects. The process of deriving has undergone the process of statutory planning, unscrupulous plan analysis, and consultation of experts' advisory committees. In order to derive the regional cooperation project, four criteria such as local uniqueness, future possibility, business promotion efficiency, and local cooperation project were set. Major projects of the Jeju Special Self-Governing Province are improvement of the surrounding traffic system, construction of the hinterland due to the construction of the second airport, and establishment of Cruise Port(Jeju Port, Seogwipo Port). The role of each entity in the implementation of regional cooperation projects is as follows. Local government should request subsidies for the projects in case of lack of budget support and secure them through competition with other regions. In addition, it should be responsible for the operation and management of the facility once it has been supported and completed smoothly. The Ministry of Land, Infrastructure and Transport affects each region through approval and subsidy of the development plan. After the development project is completed, it evaluates the development project through monitoring and plays a role of continuously improving the system. As a business operator, the provincial corporation will carry out small-scale projects including non-physical projects such as community participation. In the case of LH regional headquarters, the general manager of the region will establish a comprehensive business plan, secure development availability, and carry out large-scale growth promotion projects.

• Journal of the Economic Geographical Society of Korea
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• v.18 no.4
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• pp.539-555
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• 2015

This study proposes the methodology for measuring the time-distance accessibility on the Seoul bus system based on the T-card transaction databases and analyzes the results. T-card transaction databases contain the time/space information of each passenger's locations and times of the departure, transfers, and destination. We introduce the bus network graph and develop the algorithms for time-distance accessibility measurement. We account the average speed based on each passenger's get-in and getoff information in the T-card data as well as the average transfer time from the trip chain transactions. Employing the modified Floyd APSP algorithm, the shortest time distance between each pair of bus stops has been accounted. The graph-theoretic nodal accessibility has been given by the sum of the inverse time distance to all other nodes on the network. The results and spatial patterns are analyzed. This study is the first attempt to measure the time-distance accessibility for such a large transport network as the Seoul bus system consists of 34,934 bus stops on the 600 bus routes, and each bus route can have different properties in terms of speed limit, number of lanes, and traffic signal systems, and thus has great significance in the accessibility measurement studies.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.131-144
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• 2018

The urban center of a large city has a high concentration ratio of population, commerce, and traffic. Therefore, the expected effect is high from the introduction of the urban utility tunnel and it also has sufficient economic feasibility considering life cycle cost. Moreover, the construction cost can be greatly reduced if it is included in a large underground development such as a subway or a complex transfer center construction. However, it is not reflected in actual underground development plan. When planning a urban utility tunnel in Korea, it is expected to have difficulties such as the cost of relocation of the existing Life-Line, conflicts among the individual facility institutions, procurement of construction resources and sharing. Furthermore, it is possible to promote the project only if a consensus is drawn up by a collective council composed of all facilities and project developers. Therefore, an optimal alternative should be proposed using economic analysis and feasibility assessment system. In this study, the analytic hierarchy process (AHP) is performed considering the characteristics of urban areas and the importance of each indicator is quantified. As a result, we can support reasonable design capacity optimization using the feasibility assessment system.