• Proceedings of the Korean Magnestics Society Conference
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• 2016.11a
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• pp.20-20
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• 2016

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.63-63
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• 2003

• Proceedings of the Korean Vacuum Society Conference
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• 1996.02a
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• pp.119-119
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• 1996

• Proceedings of the Korean Magnestics Society Conference
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• 1997.11a
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• pp.8-8
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• 1997

• Journal of the Korean Institute of Navigation
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• v.13 no.3
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• pp.1-20
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• 1989

In order to provide a basic information to locate the sensor of remote-indicating magnetic compass onboard, an empirical model for the over-all ship's magnetism was developed based on the periodicity of the observed magnetic field around the vessels. The values of model parameters were determined by least-square method and optimum numbers of them were fixed using Akaike's information criterion theory, and also an approximation method to determine parameter was proposed based on the symmetrical characteristic of observed data versus ship's length. The confidence level of the newly developed models was tested by analysis of variance method. The agreement between the modelled and real values was found to be remarkably accurate.

• Journal of Astronomy and Space Sciences
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• v.32 no.2
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• pp.137-140
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• 2015

The results of the study of ionospheric variations in the summer months of 1998-2002 at an ionospheric station of vertical sounding "Petropavlovsk-Kamchatsky" are presented. Anomalous variations of virtual sporadic-E height (h'Es), Es blanketing frequency (fbEs), and the critical frequency of the ionospheric F2 layer (foF2) (which can be attributed to the possible earthquake precursors) are selected. The high efficiency of the selection of ionospheric earthquake precursors based on the several parameters of Es and F2 layers is shown. The empirical dependence, which reflects the connection between the lead-time of the earthquake moment, the distance to the epicenter from the observation point, and the magnitude of the earthquake are obtained. This empirical dependence is consistent with the results of the detection of earthquake precursors by measuring the physical parameters of the Earth's crust in the same region.

• Journal of Astronomy and Space Sciences
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• v.32 no.2
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• pp.141-144
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• 2015

In this paper we study the transmission of the electrostatic field due to coulomb charges of an individual thundercloud into the midlatitude ionosphere, taking into account the total geomagnetic field integrated Pedersen conductivity of the ionosphere. It is shown that at ionospheric altitudes, a typical thundercloud produces an insignificant electrostatic field whereas a giant thundercloud can drive the horizontal electrostatic field with a magnitude of ${\sim}270{\mu}V/m$ for nighttime conditions.

• Journal of Astronomy and Space Sciences
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• v.33 no.1
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• pp.13-19
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• 2016

In recent years, there has been renewed activity in the study of local plasma density enhancements in the low latitude F region ionosphere (low latitude plasma blobs). Satellite, all-sky airglow imager, and radar measurements have identified the characteristics of these blobs, and their coupling to Equatorial Plasma Bubbles (EPBs). New information related to blobs has also been obtained from the Communication/Navigation Outage Forecasting System (C/NOFS) satellite. In this paper, we briefly review experimental, theoretical and modeling studies related to low latitude plasma blobs.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.268-277
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• 1994

Current sensor using Hall device is an instrument of detecting a current by Hall effect. The existing current sensor is ordinarily worked by concentrating electromagnetism produced around the conducting wire turned iron core. The tiny curren, however, could not be accurately detected by the instrument owing to influence of residual magnetism exisisting in iron core, and the result of detecting is also somewhat on the large side. kAccordingly, We fabricated a new type of instrument minimizing the influence of residual magnetism existing in iron core and detected the tiny DC current accurately by taking advantage of magnetic modulation. The range of measuring DC current is 0[mA]-100[mA] and the maxiumm Linerity tolleance by the result of detecting current, can be reduced less than 3 percent.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.610-613
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• 2020

Specimens of austenitic stainless steel were irradiated with 6 MeV Xe ions to two doses of 7 and 15 dpa at room temperature and 300 ℃ respectively. Then partial irradiated specimens were subsequently thermally annealed at 550 ℃. Irradiation-induced BCC-phase formation and magnetism were analyzed by grazing incidence X-ray diffraction (GIXRD) and vibrating sample magnetometer (VSM). It has been shown that irradiation damage level, irradiation temperature and annealing temperature have significant effect on BCC-phase formation. This BCC-phase changes the magnetic behavior of austenitic stainless steel. The stress relief and compositional changes in matrix are the driving forces for BCC-phase formation in austenitic stainless steel during ion irradiation.