• Journal of Advanced Navigation Technology
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• v.8 no.2
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• pp.136-144
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• 2004

In this paper, we present an improved channel estimation method for orthogonal frequency division multiplexing systems using pilot-symbol-aided parameter estimation. Conventional linear minimum mean square error(LMMSE) channel estimation method uses only pilot symbols for channel estimation. So, as the fading channel varies rapidly, a performance is decreased. We proposed a channel estimation method, which estimates channel attenuation in the middle of pilots using pilot symbols and then estimates the whole channel attenuation with pilots and estimated channel attenuation. Compared with conventional LMMSE channel estimation method, the proposed method is significantly robust in a rapid fading channel with high Doppler frequency and delay spread.

• Journal of Advanced Navigation Technology
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• v.13 no.4
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• pp.523-531
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• 2009

In this study, we propose a joint source/channel rate control algorithm for video encoder targeting packet erasure channel. Based on the buffer constraints of video communication systems, encoding rate constraint is presented. After defining source distortion models for coded and skipped video frames and a channel distortion model for packet errors and their propagation, an average distortion model of received video is proposed for a given encoding window. Finally, we define an optimization problem to minimize the average distortion for given channel rates and packet loss rates by controlling spatio-temporal parameters of source video and FEC block sizes. Then, we propose a window-based algorithm to solve the problem in real-time.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.677-683
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• 2010

In this paper, a channel estimation scheme for high-speed Binary CDMA systems is proposed and its performances are investigated. In high-speed Binary CDMA which adopt high order modulations, since BER(bit error rate) performances are deteriorated when equalizer does not converge enough during preamble period it is preferred to set the optimum coefficients of equalizer through channel estimation. In this paper, taking notice of repetition of CAZAC sequence in preamble period, a channel estimation scheme is proposed, which can improve estimation performances with few complexity increase. From the simulation results, one can see that the proposed channel estimation scheme can be implemented simply with no performance deterioration compared to the conventional one.

• Journal of Advanced Navigation Technology
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• v.7 no.1
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• pp.51-58
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• 2003

Generally, multi-path is viewed as an undesirable feature of wireless communications. Therefore, diversity reception and adaptive array schemes are proposed to mitigate its effects. Recently, to increase the spectrum efficiency and the link reliability, multiple-input multiple-output (MIMO) scheme is devised to exploit multi-path in a scattering wireless channel. In this paper, we have evaluated the channel capacity of MIMO Multi-Carrier CDMA system in path correlation fading channel. And, the channel capacity of MIMO system is compared with single-input single-output (SISO) system. From the results, the MIMO multi-carrier CDMA system with path correlation yields better performance with respect to channel capacity than a SISO system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.237-243
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• 2005

To design ship channel is one of important factors for planning and developing a port. Bends in channel should be avoided if possible, but the channel should be widened, if channel bend is unavoided, to account widened path of a ship in bend for the safe passage of a ship. In this study, Variable Bumper Area(VBA) model is applied to determine ship channel width in bend and channel-bend geometry. The result of this study shows that the width of a channel in bend may be designed as wide as the width in straight lane provided the angle of deflection is less than 30 degree, should be widened for 60degree deflection based on the length of the largest ship using the channel and the angle of deflection.

• Journal of Advanced Navigation Technology
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• v.1 no.1
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• pp.23-34
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• 1997

A multi-channel digital GPS receiver has been developed including a RF-to-IF engine (engine 1), a digital signal processing engine (engine 2) with a microprocessor interfacing, and a navigation software. A high speed SiGe heterojunction bipolar transistor (HBT) as a active device has been mounted on chip-on-board (COB) type hybrid ICs such as LNA, mixer, and VCO in RF front-end of the engine 1 board. A 6-channel digital correlator together with a real-time clock and a microprocessor interface has been realized using an Altera Flex 10K FPGA as well as ASIC technology. Navigation software controlling the correlator for GPS signal tracking, retrieval and storing a message retrieval, and position calculation has been implemented. The GPS receiver was tested using a single channel STR2770 simulator. Successful navigation message retrieval and position determination was confirmed.

• Journal of Navigation and Port Research
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• v.27 no.6
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• pp.661-667
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• 2003

There are certain guidelines on the channel design such as domestic guidelines（Korean and japanese, etc.）and international guideline known as PIANC Rules（Permanent International Association of Navigation Congresses Rules）, in the world These rules have considered many factors such as natural conditions, ship maneuverability and geographical features etc. But it is contented toot the area of these rules toot are meant to facilitate the ease of ship-handling is insufficient. To satisfy this point in design process, it is necessary to take into account the difficulties encountered in ship-handling within these inland waterways. Because many vessels are navigating at the same time within these waterways, the specific navigable traffic volume should be considered with regard to the standard process of route designing. It must also be considered with regard to the volume of navigable traffic bemuse of ship-handling difficulty toot arises within the same waterway with varying amounts of traffic volume because toot ship-handling/manueverability is directly influenced by these factors. This paper aims to propose a new approach to the design of standard inland water route considering the traffic volume and the shape of waterway. Also consider the relationship among these factors may affect to the ship-handling difficulties.

• Journal of Navigation and Port Research
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• v.41 no.5
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• pp.345-352
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• 2017

Recently, a new port reserves deep water depth for safe navigation and mooring, following the trend of larger ship building. Larger port facilities include long and huge breakwaters, and mainly adopt vertical type considering low construction cost. A vertical breakwater creates stem waves combining inclined incident waves and reflected waves, and this causes maneuvering difficulty to the passing vessels, and erosion of shoreline with additional damages to berthing facilities. Thus, in this study, the researchers have investigated the response of stem waves at the vertical breakwater near the entrance channel and applied numerical models, which are commonly used for the analysis of wave response at the harbor design. The basic equation composing models here adopted both the linear parabolic approximation adding the nonlinear dispersion relationship and nonlinear parabolic approximation adding a linear dispersion relationship. To analyze the applicability of both models, the research compared the numerical results with the existing hydraulic model results. The gap of serial breakwaters and aligned angles caused more complicated stem wave generation and secondary stem wave was found through the breakwater gap. Those analyzed results should be applied to ship handling simulation studies at the approaching channels, along with the mooring test.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2166-2180
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• 2016

We investigate the opposite of artificial noise (AN)-assisted communication in multiple-input-multiple-output (MIMO) wiretap channels for the multiuser case by taking the side of the eavesdropper. We first define a framework for an AN-assisted multiuser multiple-input-multiple-output (MU-MIMO) system, for which eavesdropping methods are proposed with and without knowledge of legitimate users' channel state information (CSI). The proposed method without CSI is based on a modified joint approximate diagonalization of eigen-matrices algorithm, which eliminates permutation indetermination and phase ambiguity, as well as the minimum description length algorithm, which blindly estimates the number of secret data sources. Simulation results show that both proposed methods can intercept information effectively. In addition, the proposed method without legitimate users' CSI performs well in terms of robustness and computational complexity.

• Journal of the Korean Institute of Navigation
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• v.16 no.1
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• pp.65-75
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• 1992

The Waterway System for the Very Large Ships is One of the Important System connected between Marine Transport System and Exclusive Terminal. This study analyzed the Turning Configurations and Placement of Fairway Buoys in Waterway at the Port of Kwangyang to make Optimal Suggestion of for Ship's Safe Navigation. The following Conclusions are drawn : 1) In Area Section A, Starboard hand Buoy No14 should be changed its Location and Light Rhythms, and Buoy Nos.13 '||'&'||' 16 are required their Light Rhythms to be changed. 2) Especially in Area Section B located before the Turning Basin, The Location and Light Rhythms of Nos.20 '||'&'||' 22 buoys at Starboard Hand should be changed, Port Hand No.21 also should be done, and East Cardinal Buoy located between Nos.21and 23 should be changed its Light Rhythms, or removed if possible. 3) Buoy no.19 of Lateral Port Hand in Section B should be changed "Preferred Channel to Startboard" to distinguish Main Channel from Secondary One.