• Proceedings of the Korean Magnestics Society Conference
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• 1995.05a
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• pp.40-41
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• 1995

• Journal of Magnetics
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• v.18 no.2
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• pp.135-141
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• 2013

This paper proposes an efficient fault detection method for onboard degaussing coils which are installed to minimize underwater magnetic fields due to the ferromagnetic hull. To achieve this, the method basically uses field signals measured at specific magnetic treatment facilities instead of time-consuming numerical field solutions in a three-dimensional analysis space. In addition, an analytical design sensitivity formula and the linear property of degaussing coil fields is being exploited for detecting fault coil positions and assessing individual degaussing coil currents. Such peculiar features make it possible to yield fast and accurate results on the fault detection of degaussing coils. For foreseeable fault conditions, the proposed method is tested with a model ship equipped with 20 degaussing coils.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.314-314
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• 2010

The design of the blanket and shield play a key role in determining the size of a reactor since it has an impact on the various reactor components. The blanket should produce enough tritium for tritium self-sufficiency and the shield should provide sufficient protection for the superconducting TF coil. Neutronic optimization of the blanket and the shield is necessary, and we coupled the system analysis with a neutronic calculation to account for the interrelation of the blanket and shield with the plasma performance of a reactor system in a self-consistent manner. By using the coupled system analysis code, the operational space for a low aspect ratio (LAR) tokamak reactor with a superconducting toroidal field (TF) coil is investigated with an spect ratio in the range of 1.5 - 2.5. The minimum major radius which satisfies all the physics and engineering requirements increases with the magnetic field at the magnetic axis. A required inboard shield thickness is mainly determined by the requirement on the protection of the TF coil against radiation damage. It is shown that to have a fusion power bigger than 3,000 MW in the LAR tokamak with a superconducting TF coil, a major radius bigger than 4.0 m is required.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1641-1644
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• 2005

Magnetic actuation utilizes the mechanic torque that is the result of interaction of the current in a coil with an external magnetic field. A main obstacle is, however, that torques can only be produced perpendicular to the magnetic field. In addition, there is uncertainty in the Earth magnetic field models due to the complicated dynamic nature of the field. Also, the magnetic hardware and the spacecraft can interact, causing both to behave in undesirable ways. This actuation principle has been a topic of research since earliest satellites were launched. Earlier magnetic control has been applied for nutation damping for gravity gradient stabilized satellites, and for velocity decrease for satellites without appendages. The three axes of a micro-satellite can be stabilized by using an electromagnetic actuator which is rigidly mounted on the structure of the satellite. The actuator consists of three mutually-orthogonal air-cored coils on the skin of the satellite. The coils are excited so that the orbital frame magnetic field and body frame magnetic field coincides i.e. to make the Euler angles to zero. This can be done using a Neural Network controller trained by PD controller data and driven by the difference between the orbital and body frame magnetic fields.

• Progress in Superconductivity and Cryogenics
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• v.15 no.3
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• pp.29-34
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• 2013

This paper introduces design processes of 10 MW class superconducting generator for wind Turbine. Superconducting generator can produce 5 times stronger magnetic field than permanent magnet at least, which enables large scale wind turbine to function as a lighter, smaller and more highly efficient system. These processes are targeted for higher efficiency and shorter high temperature superconductor (HTS) wires to fabricate 10 MW class superconducting generator. Three different approaches will be described in these design processes. First design process focuses on the number of rotor poles. Secondly, 270 and 360 A operating current of superconducting field coil can be adapted as a design parameter in this process. Lastly, 3 and 6 kV line to line voltage of stator coil will be used to design 10 MW class superconducting generator.

• Journal of Veterinary Clinics
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• v.16 no.1
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• pp.75-79
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• 1999

Magnetic resonance imaging (MRI) is an imaging technique used to produce high quality images of the inside of the animal body. MRI is based on the principles of nuclear magnetic resonance (NMR) and started out as a tomographic imaging technique, that is it produced an image of the NMR signal in a thin slice through the animal body. The animal body is primarily fat and water, Fat and water have many hydrogen atoms. Hydrogen nuclei have an NMR signal. For these reasons magnetic resonance imaging primarily images the NMR signal from the hydrogen nuclei. Hydrogen protons, within the body align with the magnetic field. By applying short radio frequency (RF) pulses to a specific anatomical slice, the protons in the slice absorb energy at this resonant frequency causing them to spin perpendicular to the magnetic field. As the protons relax back into alignment with the magnetic field, a signal is received by an RF coil that acts as an antennae. This signal is processed by a computer to produce diagnostic images of the anatomical area of interest.

• Progress in Superconductivity and Cryogenics
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• v.12 no.1
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• pp.28-31
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• 2010

A magnetic field calculation method for toroidal type winding which has circular section was developed. At first, the equation for magnetic field by single filament coil was extended using numerical integration to estimate the entire interesting region of solenoid, especially winding region itself. And then, the magnetic field by toroidal arrangement of solenoids was computed with a coordinate transformation of vector fields. The superconducting magnet with toroidal arrangement can be made up of several tens of solenoid type double pancake windings for some applications such as superconducting magnetic energy storage system(SMES). In this system, the field calculation on the high-Tc superconducting(HTS) tape itself is very important because the entire system can be reached to a fault by magnetic stress of conductor or the critical current of superconducting tape can be dramatically reduced under its self field condition. To make matters worse, 3-dimensional analysis is indispensable for this type of magnet and the most of commercial programs with finite element method can be taken too much time for analysis and design. In this paper, a magnetic field calculation method for toroidal type winding with circular section was induced.

• Publications of The Korean Astronomical Society
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• v.15 no.spc2
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• pp.57-64
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• 2000

It is realized that the extraterrestrial matter is in ionized state, plasma, so the matter of this kind behaves as not expected because of its sensitiveness to electric and magnetic fields and its ability to carry electric currents. This kind of subtle change can be observed by an instrument for the magnetic field measurement, the magnetometer usually mounted on the rocket and the satellite, and based on the ground observatory. The magnetometer is a useful instrument for the spacecraft attitude control and the Earth's magnetic field measurements for the scientific purpose. In this paper, we present the preliminary design and the test results of the two onboard magnetometers of KARl's (Korea Aerospace Research Institute) sounding rocket, KSR­III, which will be launched during the period of 2001-02. The KSR-III magnetometers consist of the fluxgate magnetometer, MAG/AIM (Attitude Information Magnetometer) for acquiring the rocket flight attitude information, and of the search-coil magnetometer, MAG/SIM (Scientific Investigation Magnetometer) for the observation of the Earth's magnetic field fluctuations. With the MAG/AIM, the 3-axis attitude information can be acquired by the comparison of the resulting dc magnetic vector fields with the IGRF (International Geomagnetic Reference Field). The Earth's magnetic field fluctuations ranging from 10 to 1,000 Hz can also be observed with the MAG/SIM measurement.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.79-84
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• 2020

Wireless power transfer is more convenient than wired power transfer, but has a shorter transfer distance and lower efficiency. In addition, it is difficult to charge multiple devices simultaneously. In this paper, we propose a method of magnetic beam forming by using multiple transmitters in order to increase transfer distance and improve efficiency of wireless power transfer. To do this, the relationship between the transmitter coil current and magnetic field at the center of receiver coil is modelled, and calculate the optimal transmitter coil current using the characteristics of the pseudoinverse. Finally, the validity of the proposed method is verified by simulation.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.257-261
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• 2000

The value of I$_c$(critical current) in HTS (High Temperature Superconductor) tape has a great influence on B${\bot}$(vertical field). Therefore, in shape design of field coil for the HTSG(High Temperature Superconducting Generator), a method to reduce the B${\bot}$ should be considered in order to maintain the stability and substantial improvement on the performance. On the basis of the magnetic field analysis, this paper deals with various field coil shape according to the iron plate to obtain small B${\bot}$ by using Biot-Savart's law, image method and 2D FEA(2 Dimensional Finite Element Analysis) considering the stress condition of HTS. Moreover, the analysis is verified by comparison with experimental results. And also this paper presents the advanced model by using 3D FEA, in which flux density at armature is calculated in 5kVA class HTSG.