• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.4
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• pp.385-392
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• 1995

The authors have been studying about and electro-magnetic compass with a three axis magnetic sensor in order to provide and accurate ship's magnetic heading which the compass deviations can automatically compensated in the compass itself, and the theory how to derive the poisson's coefficients from ship's magnetism measured with three axis magnetic sensor. This paper describes on the analysis of deviation derived from the measured values that obtained to measure the various magnetic fields at the compass position of the M. S. ARA, training ship of Cheju University with three axis magnetic sensor at Cheju near sea from 25th, Oct, to 13th, Nov. in 1994.

• Journal of the Korean Magnetics Society
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• v.17 no.6
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• pp.259-264
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• 2007

This paper describes the mathematical modeling method for the static magnetic field signature generated by a magnetic scale model. we proposed the equivalent dipole modeling method utilizing a singular value decomposition technique from magnetic field signatures by magnetic sensors are located special depths below the scale model. The proposed dipole modeling method was successfully verified through comparisons with the real measured values in our non-magnetic laboratory. Using the proposed method, it is possible to predict and analyze static magnetic field distributions at any difference depths generated from the real ships as well as a scale model ship.

• Journal of the Korean Magnetics Society
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• v.27 no.2
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• pp.63-69
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• 2017

Naval ships are particularly required to maintain acoustic and magnetic silence due to their operational characteristics. Among them, underwater magnetic field signals derived by ships are likely to be detected by threats such as surveillance systems and mine systems at close distance. In order to increase the survivability of the vessels, various techniques for reducing the magnetic field signal are being studied and it is necessary to consider not only the magnitude of the magnetic field signal but also the gradient of it. In this paper, we use the commercial electromagnetic finite element analysis tool to predict the induced magnetic field signal of ship's scaled model, and arrange the degaussing coil. And the optimum degaussing current of the coil was derived by applying the particle swarm optimization algorithm considering the gradient constraint. The validity of the optimal degaussing technique is verified analytically by comparing the magnetic field signals after the degaussing with or without gradient constraint.

• Journal of Magnetics
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• v.21 no.2
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• pp.197-203
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• 2016

A naval ship equipped with a degaussing system may undergo a breakdown in degaussing coils at sea. In the case, underwater magnetic field around the ship abruptly grows up and it can make the ship be easily exposed to fatal hazards such as magnetic mines or torpedoes. This paper proposes an efficient and practical re-degaussing technique for a ship where a part of degaussing coils is out of order. To achieve this, an analytical design sensitivity formula and approximated degaussing coil field are exploited, and then new optimum currents of available coils are reassessed. To validate the proposed method, a muck-up ship equipped with 14 degaussing coils is tested in scale-down magnetic treatment facilities under three faulty coil conditions.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.6
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• pp.74-80
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• 2008

Analysis of the electromagnetic environment on topside of a ship is needed for optimal arrangement of all kinds of antennas to be installed on the shipboard in order to minimize the probability of EMI of equipment and subsystems in real ship after construction phase. In this paper we analyze the characteristics of electric-fields such as radiation patterns and near E-fields of V/UHF antennas installed on a shipboard. We compare simulated results with measurements on the real ship for near E-fields to verify the reliability of the computed electromagnetic environment. Although there are various factors causing errors such as cable loss and impedance mismatching etc. when measuring near E-field, both data show similar trends in the range of the acceptable tolerance.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.1
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• pp.61-67
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• 2024

A naval mine is an effective weapon system implemented for defending defends ports and seas. A mine is an underwater weapon that poses a great threat to ships sailing over the sea from shallow areas. Most of the influence-type naval mines detect magnetic field signals from ships and determine the final time of fire. Therefore, the level of underwater electro-magnetic signatures of ships is a key requirement for determining the survival of ships in wartime situations where mines are emplaced. The main reason why the high manganese steel is attracting attention for naval ship hulls is its nature as a non-magnetic steel. The non-magnetic hull does not generate electro-magnetic signatures; thus, it has the advantage improving the stealth of the ship. In this paper, I examine whether this material can be applied in the hulls material of naval ships that must be ableto reduce underwater electro-magnetic signatures by considering the non-magnetic characteristics of the first developed high manganese steel in the world.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.137-141
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• 2006

To consider the practical use of a ship's Digital Compass in earth's magnetic field high accurate Deviation and 얘 nation are required to obtain ship's true bearing. Variation can be obtain with World Magnetic Model (WMM) using the Earth's spherical harmonic model of the main field and of the secular variation at any location around the earth. Deviation can be obtain with deviation analysis and synthesis method based on the Poisson equations. As results of deviation and variation corrections to the Digital Compass, high accurate true bearing is obtained. This experiments are carried out during in the navigation of training ship 'SAE-NU-RI'.

• Journal of the Korean Institute of Navigation
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• v.14 no.1
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• pp.1-7
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• 1990

A theoretical model for the over-all ship's magnetism was developed, on the assumption that the magnetism of a three-island type vessel can be regarded as that of the prolate spheroidal magnetic body. Modelled values were determined by the simulation on the base of the theoretical analysis of the magnetic field around the above-mentioned magnetic body. The real values were made of the data observed from four different three-islands type vessels alongside the piers. The agreement between the modelled and real values was found to be accurate.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.408-411
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• 2006

• Geophysics and Geophysical Exploration
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• v.27 no.2
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• pp.119-128
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• 2024

Marine magnetic surveys provide a rapid and cost-effective method for pioneer geophysical survey for many purposes. Sea-surface magnetometers offer high accuracy but are limited to measuring the scalar total magnetic field and require dedicated cruise missions. Shipboard three-component magnetometers, on the other hand, can collect vector three components and applicable to any cruise missions. However, correcting for the ship's magnetic field, particularly viscous magnetization, still remains a challenge. This study proposes a new additional correction method for ship's viscous magnetization effect in vector data acquired by shipboard three-component magnetometer. This method utilizes magnetic data collected simultaneously with a sea-surface magnetometer providing total magnetic field measurements. Our method significantly reduces deviations between the two datasets, resulting in corrected vector anomalies with errors as low as 7-25 nT. These tiny errors are possibly caused by the vector magnetic anomaly and its related viscous magnetization. This method is expected to significantly improve the accuracy of shipborne magnetic surveys by providing corrected vector components. This will enhance magnetic interpretations and might be useful for understanding plate tectonics, geological structures, hydrothermal deposits, and more.