• Title, Summary, Keyword: magnetometer

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3-Axis Magnetometer Modeling & Simulation and Implementation for Under Water Weapon System (3축 자력계 Modeling & Simulation 및 수중무기체계 적용)

  • Lim, Byeong-Seon;Han, Seung-Hwan;Kim, Young-Kil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.12
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    • pp.3069-3078
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    • 2014
  • This research handles the performance improvement effect by the Modeling & Simulation and shows the design, implementation, test results of the new 3-axis magnetometer which is the core component of strategic offensive deploying mine. The submarine is modelled by using the commercial electromagnetic field analysis tool on numerical value, and its magnetic field characteristic is predicted in order to apply the new magnetometer to the future underwater weapon system. The method to take the performance test results of new 3-axis magnetometer in the land is shown instead of the real test result in sea by making the miniature submarine.

Light-weight Signal Processing Method for Detection of Moving Object based on Magnetometer Applications (이동 물체 탐지를 위한 자기센서 응용 신호처리 기법)

  • Kim, Ki-Taae;Kwak, Chul-Hyun;Hong, Sang-Gi;Park, Sang-Jun;Kim, Keon-Wook
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.46 no.6
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    • pp.153-162
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    • 2009
  • This paper suggests the novel light-weight signal processing algorithm for wireless sensor network applications which needs low computing complexity and power consumption. Exponential average method (EA) is utilized by real time, to process the magnetometer signal which is analyzed to understand the own physical characteristic in time domain. EA provides the robustness about noise, magnetic drift by temperature and interference, furthermore, causes low memory consumption and computing complexity for embedded processor. Hence, optimal parameter of proposal algorithm is extracted by statistical analysis. Using general and precision magnetometer, detection probability over 90% is obtained which restricted by 5% false alarm rate in simulation and using own developed magnetometer H/W, detection probability over 60~70% is obtained under 1~5% false alarm rate in simulation and experiment.

Mid-latitude Geomagnetic Field Analysis Using BOH Magnetometer: Preliminary Results

  • Hwang, Jun-Ga;Choi, Kyu-Cheol;Lee, Jae-Jin;Park, Young-Deuk;Ha, Dong-Hun
    • Journal of Astronomy and Space Sciences
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    • v.28 no.3
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    • pp.173-181
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    • 2011
  • Korea Astronomy and Space Science Institute researchers have installed and operated magnetometers at Mt. Bohyun Observatory to measure the Earth's magnetic field variations in South Korea. We, in 2007, installed a fluxgate magnetometer (RFP-523C) to measure H, D, and Z components of the geomagnetic field. In addition, in 2009, we installed a Overhauser proton sensor to measure the absolute total magnetic field F and a three-axis magneto-impedance sensor for spectrum analysis. Currently three types of magnetometer data have been accumulated. In this paper, we provide the preliminary and the first statistical analysis using the BOH magnetometer installed at Mt. Bohyun Observatory. By superposed analysis, we find that daily variations of H, D, and Z shows similar tendency, that is, about 30 minutes before the meridian (11:28) a minimum appears and the time after about 3 hours and 30 minutes (15:28) a maximum appears. Also, a quiet interval start time (19:06) is near the sunset time, and a quiet interval end time (06:40) is near the sunrise time. From the sunset to the sunrise, the value of H has a nearly constant interval, that is, the sun affects the changes in H values. Seasonal variations show similar dependences to the sun. Local time variations show that noon region has the biggest variations and midnight region has the smallest variations. We compare the correlations between geomagnetic variations and activity indices as we expect the geomagnetic variation would contain the effects of geomagnetic activity variations. As a result, the correlation coefficient between H and Dst is the highest (r = 0.947), and other AL, AE, AU index and showed a high correlation. Therefore, the effects of geomagnetic storms and geomagnetic substorms might contribute to the geomagnetic changes significantly.

Unscented KALMAN Filtering for Spacecraft Attitude and Rate Determination Using Magnetometer

  • Kim, Sung-Woo;Abdelrahman, Mohammad;Park, Sang-Young;Choi, Kyu-Hong
    • Journal of Astronomy and Space Sciences
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    • v.26 no.1
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    • pp.31-46
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    • 2009
  • An Unscented Kalman Filter (UKF) for estimation of the attitude and rate of a spacecraft using only magnetometer vector measurement is developed. The attitude dynamics used in the estimation is the nonlinear Euler's rotational equation which is augmented with the quaternion kinematics to construct a process model. The filter is designed for small satellite in low Earth orbit, so the disturbance torques include gravity-gradient torque, magnetic disturbance torque, and aerodynamic drag torque. The magnetometer measurements are simulated based on time-varying position of the spacecraft. The filter has been tested not only in the standby mode but also in the detumbling mode. Two types of actuators have been modeled and applied in the simulation. The PD controller is used for the two types of actuators (reaction wheels and thrusters) to detumble the spacecraft. The estimation error converged to within 5 deg for attitude and 0.1 deg/s for rate respectively when the two types of actuators were used. A joint state parameter estimation has been tested and the effect of the process noise covariance on the parameter estimation has been indicated. Also, Monte-Carlo simulations have been performed to test the capability of the filter to converge with the initial conditions sampled from a uniform distribution. Finally, the UKF performance has been compared to that of the EKF and it demonstrates that UKF slightly outperforms EKF. The developed algorithm can be applied to any type of small satellites that are actuated by magnetic torquers, reaction wheels or thrusters with a capability of magnetometer vector measurements for attitude and rate estimation.

Diurnal and Seasonal Variations in Mid-Latitude Geomagnetic Field During International Quiet Days: BOH Magnetometer

  • Hwang, Junga;Kim, Hyang-Pyo;Park, Young-Deuk
    • Journal of Astronomy and Space Sciences
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    • v.29 no.4
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    • pp.329-336
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    • 2012
  • Korea Astronomy and Space Science Institute researchers have installed and operated magnetometers at Bohyunsan Observatory to measure the Earth's magnetic field variations in South Korea. In 2007, we installed a fluxgate magnetometer (RFP-523C) to measure H, D, and Z components of the geomagnetic field. In addition, in 2009, we installed a Overhauser proton sensor to measure the absolute total magnetic field F and a three-axis magneto-impedance sensor for spectrum analysis. Currently three types of magnetometer data have been accumulated. In this paper, we use the H, D, Z components of fluxgate magnetometer data to investigate the characteristics of mid-latitude geomagnetic field variation. To remove the temporary changes in Earth's geomagnetic filed by space weather, we use the international quiet days' data only. In other words, we performed a superposed epoch analysis using five days per each month during 2008-2011. We find that daily variations of H, D, and Z shows similar tendency compared to previous results using all days. That is, H, D, Z all three components' quiet intervals terminate near the sunrise and shows maximum 2-3 hours after the culmination and the quiet interval start from near the sunset. Seasonal variations show similar dependences to the Sun. As it becomes hot season, the geomagnetic field variation's amplitude becomes large and the quiet interval becomes shortened. It is well-known that these variations are effects of Sq current system in the Earth's atmosphere. We confirm that the typical mid-latitude geomagnetic field variations due to the Sq current system by excluding all possible association with the space weather.

Unscented Kalman Filtering for Spacecraft Attitude and Rate Determination Using Magnetometer

  • Kim, Sung-Woo;Park, Sang-Young;Abdelrahman, Mohammad;Choi, Kyu-Hong
    • Bulletin of the Korean Space Science Society
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    • pp.36.1-36.1
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    • 2008
  • An Unscented Kalman Filter(UKF) for estimation of attitude and rate of a spacecraft using only magnetometer vector measurement is presented. The dynamics used in the filter is nonlinear rotational equation which is augmented by the quaternion kinematics to construct a process model. The filter is designed for low Earth orbit satellite, so the disturbance torques include gravity-gradient torque, magnetic disturbance torque, and aerodynamic drag. The magnetometer measurements are simulated based on time-varying position of the spacecraft. The filter has been tested not only in the standby mode but also in the detumbling mode. To stabilize the attitude, linear PD controller is applied and the actuator is assumed to be thruster. A Monte-Carlo simulation has been done to guarantee the stability of the filter performance to the various initial conditions. The UKF performance is compared to that of EKF and it reveals that UKF outperforms EKF.

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Characteristics of Magnetic Resistance on the YBCO (YBCO의 자기 저항 특성)

  • Lee, Sang-Heon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.2
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    • pp.332-334
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    • 2009
  • The magnetic properties in YBCO superconducting materials were studied. In the measurement of I-V properties, it was cleared that the mechanism of magnetic properties could not be explained by using conventional flux theory. By changing the density of external magnetic flux, changes in current voltage characteristics in which a superconducting material were also measured. The results showed that the magnetic flux is generated by a vortex current which circulates around the vortex with a sense of rotation opposite to that of the diamagnetic screening surface current. When the external magnetic field was applied to the superconducting magnetometer, some regions of the magnetometer will be destroyed, especially the weak link regions and the defect regions.

Designs and Fabrications of High-TC SQUID Magnetometer for Measuring a Weak Signal without Magnetic Shielding (비자기 차폐환경에서 미세자기신호 측정을 위한 고온 초전도 SQUID 자력계의 설계 및 제작)

  • Yu, K.K.;Kim, I.S.;Park, Y.K.
    • Journal of Sensor Science and Technology
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    • v.13 no.2
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    • pp.110-113
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    • 2004
  • We have designed and fabricated the YBCO single layer directly-coupled SQUID magnetometers for the purpose of magnetocardiography in a magnetically disturbed environment. The SQUID magnetometers were designed three different types of pickup coil such as solid type, PL type I and PL type II for further stable fluxed-locked-loop operation without magnetic shielding. Magnetometer was fabricated with a single layer YBCO thin film deposited on STO(100) bicrystal substrate with misorientation angle of $30^{\circ}$. We have achieved a magnetic field noise BN of 30 fT/$Hz^{1/2}$ at 100 Hz, and less than 70 fT/$Hz^{1/2}$ at 1 Hz. The PL type II SQUIDs have exhibited the most stable fluxed-locked-loop operation in a magnetically unshielded environment.

A Study on the Geomagnetic Reference Field Modeling from the Triaxial Magnetometer Data Onboard KOMPSAT-II (아리랑위성 2호의 삼축자력계로부터 관측된 지구자기장 모델 연구)

  • Kim, Hyung-Rae;Hwang, Jong-Sun;Kim, Jeong-Woo;Lee, Seon-Ho
    • Economic and Environmental Geology
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    • v.45 no.4
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    • pp.377-384
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    • 2012
  • The main field component of the Earth's magnetic field was modeled from the tri-axial magnetometer onboard KOrean MultiPurpose SATellite-II (KOMPSAT-II) for the purpose of satellite attitude control. The model computed by the KOMPSAT-II magnetometer measurement data is compared with the International Geomagnetic Reference Field (IGRF) model of a degree of up to 13 in spherical harmonic coefficients. The previous study with KOMPSAT-I (Kim et al. 2004) indicated a good correlation of power spectrum of spherical harmonic coefficients with respect to the degree up to 5. This study, however, showed an agreement of the degree up to 8-9 of the coefficient power spectrum and a discrepancy between degrees 10 and 13. We have concluded that relevant data selection process, removal of the external field from the data in the high latitude region, an accuracy of the magnetometer all play an important role in finding a coherence with the IGRF model. This study will be extended to the secular variation model of geomagnetism if longer-period data become available.

ACQUISITION OF THE FLIGHT INFORMATION USING THE KSR-3 MAGNETOMETER (KSR-3 탑재 자력계를 이용한 비행정보 획득 연구)

  • Kim, Sun-Mi;Jang, Min-Hwan;Lee, Dong-Hun;Han, Young-Seok;Kim, Jun;Hwang, Seung-Hyun;Lee, Eun-Seok;Lee, Sun-Min;Kim, Hyo-Jin;Lee, Su-Jin
    • Journal of Astronomy and Space Sciences
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    • v.20 no.1
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    • pp.29-42
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    • 2003
  • The KSR-3 magnetometers consist of the fluxgate magnetometer (MAG/AIM) for acquiring the rocket flight attitude information, and the search-coil magnetometer (MAG/SIM) for the observation of the Earth's magnetic fluctuations. The position (latitude, longitude, and height) and flight condition (the transformation angle) of the rocket is measured after the data based on these two magnetometers are compared with IGRF The gap in the vector of magnetic field between the position of the launching point and an impact point is taken into account in data reduction. Angular variation of pitch, yaw, and roll can be researched when the data is applied to the coordinate system of the rocket.