• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.61-65
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• 2003

A magnetic field sensor is fabricated with superconducting ceramics system The prepared material shows the superconductivity at about 95K. The sensor at liquid nitrogen temperature shows the increase in electrical resistance by applying magnetic field. Actually, the voltage drop across the sensor is changed from zero to a value more than $100{\mu}V$ by the applied magnetic field. The change in electrical resistance depends on magnetic field. The sensitivity of this sensor is 2.9 ohm/T. The increase in electrical resistance by the magnetic field is ascribed to a modification of the Josephson junctions due to the penetrating magnetic flux into the superconducting material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.339-341
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• 2007

Soft ferromagnetic materials are very useful for many sensors using magnetic materials with high permeability, low coercivity and low hysteresis loss. Among them, FeCoSiBNi amorphous magnetic films show us a good impedance change(about 3.05%/Oe, at 12MHz) by the exterior magnetic field in this experiment. These are produced by rapid solidification from the melt and the material is ejected in a jet from a nozzle and quenched in a stream of liquid. After that, we make them a shape of wire with different sizes of width. Thus, we can find that the impedance change (122.16%, at 12MHz) is occurred and the fabricated magnetic wire has the characteristics of good sensor element.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.1962-1971
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• 2022

The liquid lead-lithium (Pb-17Li) blanket has many applications in fusion reactors due to its good tritium breeding performance, high heat transfer efficiency and safety. The compatibility of liquid Pb-17Li alloy with the structural material of blanket under magnetic field is one of the concerns. In this study, corrosion experiments China low activation martensitic (CLAM) steel and 316L steel were carried out in a forced convection Pb-17Li loop under 1.0 T magnetic field at 480 ℃ for 1000 h. The corrosion results on 316L steel showed the characteristic with a superficial porous layer resulted from selective leaching of high-soluble alloy elements and subsequent phase transformation from austenitic matrix to ferritic phase. Then the porous layers were eroded by high-velocity jet fluid. The main corrosion mechanism of CLAM steel was selective dissolution-base corrosion attack on the microstructure boundary regions and exclusively on high residual stress areas. CLAM steel performed a better corrosion resistance than that of 316L steel. The high Ni dissolution rate and the erosion of corroded layers are the main causes for the severe corrosion of 316L steel.

• Progress in Superconductivity and Cryogenics
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• v.15 no.2
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• pp.20-23
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• 2013

For sensitive measurements of micro-Tesla nuclear magnetic resonance (${\mu}T$-NMR) signal, a low-noise superconducting quantum interference device (SQUID) system is needed. We have fabricated a liquid He dewar for an SQUID having a large diameter for the pickup coil. The initial test of the SQUID system showed much higher low-frequency magnetic noise caused by the thermal magnetic noise of the aluminum plates used for the vapor-cooled thermal shield material. The frequency dependence of the noise spectrum showed that the noise increases with the decrease of frequency. This behavior could be explained from a two-layer model; one generating the thermal noise and the other one shielding the thermal noise by eddy-current shielding. And the eddy-current shielding effect is strongly dependent on the frequency through the skin-depth. To minimize the loop size for the fluctuating thermal noise current, we changed the thermal shield material into insulated thin Cu mesh. The magnetic noise of the SQUID system became flat down to 0.1 Hz with a white noise of 0.3 $fT/{\surd}Hz$, including the other noise contributions such as SQUID electronics and magnetically shielded room, etc, which is acceptable for low-noise ${\mu}T$-NMR experiments.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.109-111
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• 2000

A magnetic field sensor is fabricated with superconducting ceramics of Y-Ba-Cu-O system. The prepared material shows the superconductivity at about 95K. The sensor at liquid nitrogen temperature shows the increase in electrical resistance by applying magnetic field. Actually, the voltage drop across the sensor is changed from zero to a value more than 100$\mu$V by the applied magnetic field. The change in electrical resistance depends on magnetic field. The sensitivity of this sensor is 2.9 ohm/T. The sensing limit is about $1.5\times$$10^{-5}$ (=1.5$\times$$10^{-1}$ G). The increase in electrical resistance by the magnetic field is ascribed to a modification of the Josephson junctions due to the penetrating magnetic flux into the superconducting material.

• Nuclear Engineering and Technology
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• v.40 no.3
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• pp.213-224
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• 2008

The pumping of coolant in a liquid metal fast reactor may be performed with an annular linear induction electro-magnetic (EM) pump. Linear induction pumps use a traveling magnetic field wave created by poly-phase currents, and the induced currents and their associated magnetic field generate a Lorentz force, whose effect can be the pumping of the liquid metal. The flow behaviors in the pump are very complex, including a time-varying Lorentz force and pressure pulsation, because an induction EM pump has time-varying magnetic fields and the induced convective currents that originate from the flow of the liquid metal. These phenomena lead to an instability problem in the pump arising from the changes of the generated Lorentz forces along the pump's geometry. Therefore, a magneto-hydro-dynamics (MHD) analysis is required for the design and operation of a linear induction EM pump. We have developed a time-harmonic 2-dimensional axisymmetry MHD analysis method based on the Maxwell equations. This paper describes the analysis and numerical method for obtaining solutions for some MHD parameters in an induction EM pump. Experimental test results obtained from an induction EM pump of CLIP-150 at the STC "Sintez," D.V. Efremov Institute of Electro-physical Apparatus in St. Petersburg were used to validate the method. In addition, we investigated some characteristics of a linear induction EM pump, such as the effect of the convective current and the double supply frequency (DSF) pressure pulsation. This simple model overestimated the convective eddy current generated from the sodium flow in the pump channel; however, it had a similar tendency for the measured data of the pump performance through a comparison with the experimental data. Considering its simplicity, it could be a base model for designing an EM pump and for evaluating the MHD flow in an EM pump.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.28-34
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• 1985

This paper describes that the characteristic of movement and the performance of the directional system of the liquid magnetic compass analyze and investigate in the kinds of compass and the coefficient of viscosity of the liquid of compass, which the horizontal magnetic field of the geo-magnetic is varied from the equator to the polar region (0.39 gauss-0.03 gauss) by use of apparatus generating artificial magnetic fields. The results are as follows; 1. It is confirmed that the measured values and the calculated values on the characteristic of damping curve by the type of compass and coefficient of viscosity has almost agree with one another. 2. As the horizontal magnetic force geo-magnetic field approaches around the equator (0.39 gauss), the horizontal magnetic field get near the polar region (0.03 gauss), its period is to be longer and the compass card prove not to be more stabilized. 3. The coefficient of viscosity of the liquid in the A, B, C, D and E compasses used in the experiment is estimated 0.03 poises, 0.02 poises, 0.02 poises, 0.015 poises and 0.048 poises respectively by computer simulation.

• The monthly packaging world
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• s.248
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• pp.64-67
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• 2013

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.431.2-431.2
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• 2014

The dielectric breakdown voltage (DBV) is a measure of an insulating fluids ability to withstand a high electric field stress without breaking down. Conventionally, the presence of water or particulate matter in a dielectric fluid comprises the liquid's breakdown strength. However, the addition of magnetic nanoparticles (MNPs) in the base oil can increase the dielectric breakdown voltage of the fluid reversely, if the condition of the added particles in the fluid is in balance with that of keeping down the initiation and propagation of electrical streamers. In this study, we developed a mathematical model by a set of coupled, nonlinear equations using the COMSOL multiphysics finite element simulation suite and calculated the dielectrophoretic activity of magnetic nanoparticles suspended in the presence of electric field, which is the behavior responsible for enhancing the dielectric characteristics of transformer oil, in order to examine how the activity differ in a transformer oil-based magnetic fluid.

• Journal of Magnetics
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• v.21 no.2
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• pp.204-208
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• 2016

This paper demonstrates the key parameter detection for smelting of submerged arc furnace (SAF) based on magnetic field radiation. A magnetic field radiation model for the inner structure of SAF is established based on relative theory of electromagnetic field. A simple equipment of 3D magnetic field detection system is developed by theoretical derivation and simulation. The experiments are carried out under the environment of industrial field and AC magnetic field generated by electrode currents and molten currents in the furnace is reflected outside of the furnace. The experimental results show that the key parameters of smelting including the position of electrode tip, the length of electric arc, and the liquid level of molten bath can be achieved. The computed tomography for SAF can be realized by the detection for smelting.