• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.7
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• pp.566-572
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• 2014

We propose a two-way multi-hop relaying scheme improving the throughput as well as enlarging the coverage for ship-to-ship communications in multi-ship marine networks. The proposed scheme reduces the time slots required for the data exchange by designing data transmission and network coding procedures in a sophisticated way based on two-phase digital network coding. Simulation results show that the proposed two-way multi-hop relaying scheme improves the throughput of the conventional one about 5/3 times.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.964-973
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• 2015

Ship Area Network(SAN) can monitor the status of ship in real time and minimize the maintenance costs by connecting various devices to the network. In particular, among researches on SAN, Wireless Sensor Network using sensor nodes that is low-cost, low-power, and multifunctional has a number of advantages. In this paper, we propose cluster-based multi-channel algorithm considering the energy efficiency in wireless sensor network in a ship. The proposed algorithm shows the result of improvement of throughput and energy efficiency, because it reduces interference between clusters by using channel allocation algorithm that is distributed and dynamic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.7
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• pp.538-545
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• 2014

This paper proposes a coordinated multi-point (CoMP) based dynamic transmission scheme in a downlink multi-ship network, where a central ship selects a ship in order to maximize the utility function. The proposed scheduling scheme dynamically decides to the usage of the coordinated multi transmissions and selects a user to be served for every frame, in order to the utility function on the basis of the throughput and fairness. In particular, the proposed utilify function based scheduling scheme aims to increase the quality of service of ships at the edge of cells. Under the proportional fair scheduling, the simulation results show that the proposed utility function-based scheduling improves the throughput of the ships at the cell edge with the little sacrifice of the system capacity.

• Journal of Communications and Networks
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• v.18 no.1
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• pp.65-74
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• 2016

Ship ad-hoc network (SANET) extends the coverage of the maritime communication among ships with the reduced cost. To fulfill the growing demands of real-time services, the SANET requires an efficient clock time synchronization algorithm which has not been carefully investigated under the ad-hoc maritime environment. This is mainly because the conventional algorithms only suggest to decrease the beacon collision probability that diminishes the clock drift among the units. However, the SANET is a very large-scale network in terms of geographic scope, e.g., with 100 km coverage. The key factor to affect the synchronization performance is the signal propagation delay, which has not being carefully considered in the existing algorithms. Therefore, it requires a robust multi-hop synchronization algorithm to support the communication among hundreds of the ships under the maritime environment. The proposed algorithm has to face and overcome several challenges, i.e., physical clock, e.g., coordinated universal time (UTC)/global positioning system (GPS) unavailable due to the atrocious weather, network link stability, and large propagation delay in the SANET. In this paper, we propose a logical clock synchronization algorithm with multi-hop function for the SANET, namely multi-hop clock synchronization for SANET (MCSS). It works in an ad-hoc manner in case of no UTC/GPS being available, and the multi-hop function makes sure the link stability of the network. For the proposed MCSS, the synchronization time reference nodes (STRNs) are efficiently selected by considering the propagation delay, and the beacon collision can be decreased by the combination of adaptive timing synchronization procedure (ATSP) with the proposed STRN selection procedure. Based on the simulation results, we finalize the multi-hop frame structure of the SANET by considering the clock synchronization, where the physical layer parameters are contrived to meet the requirements of target applications.

• Proceedings of KOSOMES biannual meeting
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• 1999.03a
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• pp.7-17
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• 1999

This paper describes design techniques on the ship simulator system adopting virtual reality technology. Ship handling, generally, is done by the multi workers such as Captain, Officer, Pilot and Quartermaster. With this special fact, we proposed multi client-server network and hardware architecture which fit to the Virtual Reality Ship Simulator.

• Journal of information and communication convergence engineering
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• v.9 no.5
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• pp.523-529
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• 2011

In this paper an inter-layer protocol, referred to as a Multi-Network Selector (MNS) is proposed for multiband maritime networks. A MNS is located between the data-link layer and the network layer and performs vertical handover when a ship moves another radio network. In order to provide seamless data transfer to different radio networks, the MNS uses received signal strength (RSS) and ship's location information as decision parameters for vertical handover, which can avoid ping-pong effect and reduces handover latency. In addition, we present related issues in order to implement the MNS for a multiband maritime network.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.285-290
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• 2006

This paper presents an adaptive neural network based controller and its application to Dynamic Positioning (DP) control system of ship. The proposed neural network based controller is developed for station-keeping and low-speed maneuvering control of ship. At first, the DP system configuration is described. And then, to validate the proposed DP system, computer simulations of station-keeping and low-speed maneuvering performance of a multi-purpose supply ship are presented under the influence of measurement noise, external disturbances such as sea current, wave, and wind. The simulations have shown the feasibility of the DP system in various maneuvering situations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.950-956
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• 2015

In this paper, a WiMedia Distributed-MAC (D-MAC) protocol is adopted for development of a seamless N-screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU (One Source Multi Use) N-screen service through P2P streaming in the seamless D-MAC protocol, a ATMT (Asynchronous Traffic Multi-hop Transmission) technology is proposed and analyzed. In this system, a WiMedia ATMT D-MAC bridge transmits control and managing information to various sensors and instruments, from a central integrated ship area network station. For this technology, a time slot allocation scheme for WiMedia asynchronous traffic and a multi-hop resource reservation scheme are combined to evaluate the performance of each scheme. From simulation results, the proposed ATMT scheme enhances performances in viewpoints of N-screen asynchronous data latency and throughput, compared to the conventional WiMedia D-MAC system.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.133-140
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• 2010

NMEA2000 protocol known as IEC61162-3 of Multi-talker, Multi-listener, PnP communication is adopted as standard network for SOLAS ship by ISO in 2008 for e-navigation ages. NMEA2000 network uses well known CAN in physical layer. In this paper, address claim function is implemented for protocol converter device which can be used easily in combination with CPU of non network device. We are going to implement full function of NMEA2000 protocol and provide guideline to develop ship equipment to be networked easily.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.6
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• pp.1185-1192
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• 2015

A wireless bridge is essential to transmit control and managing information to sensors or instruments from a central integrated ship area network station. In this paper, a WPAN protocol is adopted for development of a seamless N-screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU (One Source Multi Use) N-screen service through P2P streaming in the seamless WPAN protocol, a Grid-based WPAN networking technology is proposed and analyzed. The proposed Grid-based WPAN networking technology supports multi-path and fast path-setup functions for N-screen communications. The simulation results demonstrate that the proposed Grid-based WPAN networking technology outperforms the IEEE 802.15.4 based network in terms of N-screen transmission delay.