• Journal of Sensor Science and Technology
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• v.22 no.2
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• pp.111-117
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• 2013

The autonomous driving method using magnetic sensors recognizes the position by measuring magnetic fields in autonomous robots or vehicles after installing magnetic markers in a moving path. The Position estimate method using magnetic sensors has an advantage of being affected less by variation of driving environment such as oil, water and dust due to the use of magnetic field. It also has the advantages that we can use the magnet as an indicator and there is no consideration for power and communication environment. In this paper, we propose an efficient sensor system for an autonomous driving vehicle supplemented for existing disadvantage. In order to efficiently eliminate geomagnetism, we analyze the components of the horizontal and vertical magnetic field. We propose an algorithm for position estimation and geomagnetic elimination to ease analysis, and also propose an initialization method for sensor applied in the vehicle. We measured and analyzed the developed system in various environments, and we verify the advantages of proposed methods.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.242-242
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• 2002

The Earth's magnetic field acquired from KOMPSAT-1's TAM (Three-Axis Magnetometer) between June 19th and 21st 2000 was analyzed. The TAM, one of the KOMPSAT-1's Attitude and Orbit Control Subsystems, plays an important role in determining and controlling the satellite's attitude. This also can provide new insight on the Earth's magnetic field. By transforming the satellite coordinate from ECI to ECEF, spherical coordinate of total magnetic field was achieved. These data were grouped into dusk (ascending) and dawn (descending) data sets, based on their local magnetic times. This partitioning is essential for performing 1-D WCA (Wavenumber Correlation Analysis). Also, this enhances the perception of external fields in the Kompsat-1's TAM magnetic maps that were compiled according to different local. The dusk and dawn data are processed independently and then merged to produce a total field magnetic anomaly map. To extract static and dynamic components, the 1-D and 2-D WCAs were applied to the sub-parallel neighboring tracks and dawn-dusk data sets. The static components were compared with the IGRF, the global spherical harmonic magnetic field model. The static and dynamic components were analyzed in terms of corefield, external, and crustal signals based on their origins.

• Journal of Electrical Engineering and Technology
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• v.6 no.6
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• pp.799-805
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• 2011

This study presents three different magnetization models for identifying unknown magnetization of the ferromagnetic thin plate of a ship. First, the forward problem should be solved to accurately predict outboard magnetic fields due to the magnetization distribution estimated at a certain time. To achieve this, three different modeling methods for representing remanent magnetization (i.e., magnetic charge method, magnetic dipole array method, and magnetic moment method) were utilized. Material sensitivity formulas containing the first-order gradient information of an objective function were then adopted for an efficient search of an optimum magnetization distribution on the hull. The validity of the proposed methods was tested with a scale model ship, and field signals predicted from the three different models were thoroughly investigated with reference to the experimental data.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.323-324
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• 1996

In the present work we introduce a new flare activity indicator, MAD and examine its characteristics by analyzing a set of successive three days' observations of a typical active region, AR2372. The computed MAD is compared with conventional activity indicator such as separator. It is found that. (1) MAD traces very well the separator, (2) it. singles out. local discontinuity of magnetic field lines and (3) it. is a good measure of describing the evolutionary status of active region.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.65-68
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• 2004

A lot of R&D efforts are being concentrated on the development of high performance HTS coated conductors(CC). Unlike the HTS Bi-2223 tape, a variety of processes have been tried to fabricate CC tapes. PLD and MOD are believed to be very effective methods, and high critical currents of long length CC tape have been reported. In this study, we prepared two kinds of YBCO CCs to evaluate electromagnetic property. One is YBCO tape deposited on IBAD template by PLD and the other is AMSC's MOD CC tape Critical current (Ic) in magnetic fields, its angular dependency, and n-value were measured and analyzed. Magnetic field property of Ic was appeared to be different due the fabrication process. MOD tape showed higher in-field property, n-value of both PLD and MOD tapes exponentially decreased with magnetic field. MOD tape showed higher n-value in whole magnetic fields.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.2
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• pp.177-185
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• 2012

Corrosion currents flow through the seawater due to the different electrochemical potential between a hull and a propeller under the draft line of ship. Additionally, in order to protect the hull and other sensitive anodic parts of the ship from corrosion, the corrosion protection system, called impressed current cathodic protection(ICCP) equipment has been installed in most naval ships. Those currents could be harmful to the electromagnetic silencing of the naval ship because sea mines are triggered by even a feeble field value. In this paper, we described electric and corrosion related magnetic fields by ship's galvanic corrosion and a corrosion protection system, and prediction results of electric and corrosion related magnetic fields at any depth for the model ship.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.107.2-107.2
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• 2011

Most astrophysical systems are turbulent and magnetized. Magnetic field plays an important role in the dynamics of astrophysical system and influence all of properties of astrophysical system. Therefore, information of magnetic field is very important to understand properties of astrophysical system. One way to obtain information of magnetic field is to use rotation measure. Mean strength of the magnetic field along the line of sight can be estimated from RM/DM, where RM is rotation measure and DM is dispersion measure. For the estimation of magnetic field strength using RM/DM, the correlation between density and magnetic field. When there is no correlation between density and magnetic field the relation gives exact mean magnetic strength. But if the positive correlation, it overestimates the magnetic field strength, while if the correlation is negative, it underestimate the magnetic field strength. In general, the ICM (intracluter medium) and the ISM (interstellar medium) cases, viscosity has a value greater than magnetic diffusion. We performed compressible MHD turbulence simulations and we studied correlation between density and magnetic field in different values of viscosity and magnetic diffusion. In most cases, we found weak or negative relations between the density and magnetic fields. We discuss implication of our results.

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.83-83
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• 2006

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.144-146
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• 2001

This paper deals with analysis method of single-phase line-start permanent magnet motors. Unbalanced magnetic fields produced by single-phase input make analysis difficult. To solve this unbalanced magnetic fields, this paper proposed symmetrical components transformations as well as d-q axis ones. Parameters in d-q voltage equations were calculated by Finite Element Analysis.

• Journal of The Korean Astronomical Society
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• v.36 no.spc1
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• pp.29-36
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• 2003

Quiescent solar radiation, at microwave spectral regime, is dominated by gyroresonant and thermal Bremsstrahlung radiations from hot electrons residing in solar active region corona. These radiations are known to provide excellent diagnostics on the coronal temperature, density, and magnetic field, provided that spatially resolved spectra are available from observations. In this paper we present an imaging spectroscopy implemented for a bipolar active region, AR 7912, using the multifrequency interferometric data from the Owens Valley Solar Array (OVSA), as processed with a new imaging technique, so-called Spatio-Spectral Maximum Entropy Method (SSMEM). From the microwave maps at 26 frequencies in the range of 1.2-12.4 GHz at both right- and left-circular polarizations, we construct spatially resolved brightness spectra in every reconstructed pixel of about 2 arcsec interval. These spectra allowed us to determine 2-D distribution of electron temperature, magnetic field of coronal base, and emission measure at the coronal base above the active region. We briefly compare the present result with existing studies of the coronal active regions.