• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.199-200
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• 2006

This paper describes how to generate stereoscopic sonar images by using multibeam data. Both parallel and crossing methods were used to create stereoscopic vision of the seafloor. Stereoscopic sonar images might provide reality and more detailed information of the target and the seafloor topography.

• Korean Journal of Remote Sensing
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• v.11 no.3
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• pp.129-145
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• 1995

SeaBeam2000, a multibeam echo sounder, is a new generation seabed mapping system of which a single swath covers an angular range of -60.deg. to 60.deg. from the vertical direction with 121 beams. It provides high-density and high-quality bathymetric data along with sidescan acoustic data. The purpose of the research is to develop a system for processing multibeam underwater acoustic and bathymetric data using digital signal processing techniques. Recently obtained multibeam echo sounder data covering a survey area in the East Sea of Korea ($37{\circ}$.00'N to $37{\circ}$30'N and $129{\circ}$40'E to $130{\circ}$30'E) are preliminarily processed using the developed system and reproduced in the raster image format as well as three dimensionally visualized form.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.6
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• pp.2546-2566
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• 2016

This paper investigates an efficient transmission scheme for the remote wireless sensors to receive information which is rarely discussed in the integrated remote wireless sensor and multibeam satellite networks (IWSMSNs). The networks can be employed to exchange sensing information for emergency scenario, ocean scenario, and so on, which are isolated from available terrestrial networks. As the efficient transmission link is important to the IWSMSNs, we propose a hybrid full frequency (HFF) precoding by taking advantage of frequency reuse and multiple-input multiple-output (MIMO) precoding. Considering energy efficiency and sinks fairness are crucial to transmission link, thus the HFF precoding problems are formulated as transmit power minimization (TPM) and max-min fair (MMF) received signal to interference plus noise ratio (SINR) problems, which can be transformed to indefinite quadratic optimization programs. Then this paper presents a semi-definite programming (SDP) algorithm to solve the problems for the IWSMSNs. The promising potential of HFF for the real IWSMSNs is demonstrated through simulations.

• Ocean and Polar Research
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• v.28 no.4
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• pp.467-473
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• 2006

The EM 120, a newly installed multibeam echo sounder on RM Onnuri, has several advantages over the previously installed SeaBeam 2000 in performance and thus data quality. The EM 120 system provides a bottom topographic map with high resolution by (1) increasing the number of beams, (2) increasing the across track swath range, (3) measuring the more accurate sound velocity within the water column, and (4) improving stabilization for pitching, rolling, and yawing of the ship. This study compares EM 120 and SeaBeam 2000 echo sounders in terms of the data quality from the same survey area in the Clarion-Clipperton Zone, NE Pacific. Our result shows that the EM 120 provides more precise topographic data than the SeaBeam 2000. Although overall trends of data, such as topographic direction and relief, are similar for both echo sounders, the water depths measured by the EM 120 are shallower than that of SeaBeam 2000 by 80 to 90 meters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.756-759
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• 2012

This paper presents the multibeam service coverage of GEO(Geostationary Orbit) satellite and the practical antenna scheme scenarios to provide the universal communication services on the Korean peninsula. The proposed antenna systems consist of the simplest scheme and feed network so that they can be mounted on satellites. The feed networks are effectively organized according to the frequency and polarization plan. Despite simple structure, all scenarios meet the electrical performance by the optimization of feed allocation and feed excitation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1090-1097
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• 2007

The multibeam surveillance radar is a state-of art of 3D radar technology. It applies the stacked beam-on-received realized by a digital beamformer. In this paper, a design concept of beamformer and a method of target altitude extraction for multibeam surveillance radar in the normal environmental condition considering no multipath situations are proposed and investigated. The extraction algorithm based on antenna sine space coordinated system in a FFT digital beamformer is described. The proposed algorithm is simulated by 1 look-up table data and confirmed to have consistent results in accordance with a variety of target altitudes and a full radar frequency range.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3A
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• pp.140-150
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• 2003

In this paper, we propose a novel code sharing method for downlink transmission of mobile satellite communication systems using a multibeam geosynchronous-orbit satellite. In the proposed system, spreading codes are shared among downlink beams in order to increase the system capacity. We also propose efficient radio resource and transmit power allocation schemes for the proposed system. Simplified analysis and simulation results on the system capacity show the capacity improvement by the proposed scheme. The simulation results show that the capacity of the proposed system is more than 2 times as large as that of a conventional multibeam satellite system. In the frequency-selective fading channel, the capacity improvement increases as the interference between orthogonal spreading codes decrease.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.3
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• pp.199-207
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• 2013

In hydrographic survey, data surveyed with multibeam system includes various errors due to multiple factors. These are corrected by a calibration called patch test, and if existing method is used, the test needs to be conducted for about 8 times for precise system calibration. For more prompt and precise multibeam system calibration, the exact offset of a ship was determined using terrestrial laser scanning and TS surveying, which was used as the initial input for the patch test. In the result, the error of closure was 0.001 m or less for TS surveying and backsight error was 0.005 m or less for scanning. All the surveying data based on the same local coordinate was converted into vessel reference coordinate during which R-square for all rotation angles was 0.99 or higher and standard deviation was 0.008 m or less. Finally, in a patch test using calculated offset of sensors and motion sensor offset, the offset of MBES transducer satisfied manual on hydrography only with 1-time calibration. With these results, it is thought that terrestrial laser scanning and TS surveying can fully be utilized for multibeam system calibration.

• The Bulletin of The Korean Astronomical Society
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• v.25 no.2
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• pp.45-45
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• 2000

• Bulletin of the Korean Space Science Society
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• 2000.10a
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• pp.45-45
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• 2000

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