• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.622-624
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• 2014

A maglev train records a host of physical variables such as gaps, voltages and currents for suspension control and monitoring purposes. These data available from a maglev contains wealth of information that can be explored for various uses. One possible of such application is to use the gap data to estimate the shape of the rail, especially at the joints where rails are connected. The eddy current sensors that measure the gap between the rail and the car body produce large peaks around the joints. The suspension controller discards these peaks. Since the shape of the peaks is related to the joint, however, these peaks can be utilized to estimate the shape of the joints. In this paper, we present preliminary results on estimating the joint shape using the peak data. The results show that the approach is promising, albeit several technical difficulties to overcome.

• Journal of Magnetics
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• v.13 no.4
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• pp.173-176
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• 2008

In this study, a new kind of instrument for measuring the magnetic shielding effectiveness (MSE) was developed using a double yoke; one a magnetizing yoke and the other a sensing yoke. Using the developed instrument, the MSE could be measured for a steel sheet specimen in the ELF range, where the magnetic permeability contributes to the MSE at low frequencies and eddy currents contributes to the MSE high frequencies with < 0.1 dB reproducibility. The developed measuring method can be applied to quality control in a steel sheet company producing EMI/EMC shielding materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.79-82
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• 2002

Induction heating is widely used in today's industry, in operations such as metal hardening, preheating for forging operations, melting or cooking. In this paper, it was presented the magneto-thermal analysis of an induction heating jar(IH-JAR) with the material value of the stainless and the aluminum for efficient design. The magnetic field intensity inside the axisymmetric shaped cooker was analyzed using three-dimensional axisymmetric finite element method(FEM) and the effectual heat source was obtained by ohmic losses from eddy currents induced in the jar. The heat was calculated using the heat source and heating equation. Also, it was represented the temperature characteristics of the IH-JAR according to time and relative permeability in stainless parts and in aluminum parts.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.287-289
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• 2000

Induction heating is utilized in a large and ever-increasing number of application. The most prominent of these are billet heating heat treating, metals joining, and metal melting. In these day, heating roll, a kind of induction heating, is widely used in curing of coatings and fiber industry. In this paper, at first, treated that heating roll's characteristics equation. The second, analysis of magnetic flux and eddy currents distribution using FEM.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1078-1080
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• 1993

The quench performance and ramp rate sensitivity of eighteen 5-cm-aperature, 15-m-long SSC dipole magnet prototypes are discussed. All the magnets appear to reach a quench plateau near their extrapolated short sample current limit and well in excess of the operating current with very little training. Most of the magnets, however, exibit a dramatic degradation of thier quench current as a function of ramp rate, which for the most part, can be attributed to large cable eddy currents.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.23-25
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• 2005

This paper describes analysis of transformer sheet winding losses and temperature rise. Sheet windings are used if transformer rating currents are so high that one meets current density limit on windings. Unlike stranded windings, sheet windings may be locally healed due to R direction flux. Winding losses with eddy current effect are calculated by finite element electromagnetic analysis and temperature rise is also calculated by Computational Fluid Dynamics (CFD) with loss result.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.68-70
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• 1995

The controller for magnetically suspended vehicles considering the speed characteristics is presented. Generally, the attraction force of magnet is determined by input current and air gap. However, when MAGLEV runs at high speed, induced eddy currents in the rail decrease the attraction force. Thus control characteristics of MAGLEV become deteriorated. Therefore, the variation of attraction force according to speed must be considered. Thus we analyzed the speed characteristics of the magnet by FEM. Also, we study on the control characteristics according to speeds, and design the controller considering the decline of levitation force using Neural Network.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.5
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• pp.291-298
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• 2015

An array type probe for monitoring metal tubes is proposed in this paper which utilizes peak value and peak time of a pulsed eddy current(PEC) signal. The probe consists of an array of encircling coils along a tube and the outside of coils is shielded by ferrite to prevent source magnetic fields from directly affecting sensor signals since it is the magnetic fields produced by eddy currents that reflect the condition of metal tubes. The positions of both exciter and sensor coils are consecutively moved automatically so that manual scanning is not necessary. At one position of send-receive coils, peak value and peak time are extracted from a sensor PEC signal and these data are accumulated for all positions to form an array type peak value signal and an array type peak time signal. Numerical simulation was performed using the backward difference method in time and the finite element method for spatial analysis. Simulation results showed that peak value increases and the peak appears earlier as the defect depth or length increases. The proposed array signals are shown to be excellent in reflecting the defect location as well as variations of defect depth and length within the array probe.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.2
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• pp.137-147
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• 1970

From November 1968 to March 1970, a series of drift bottle experiments were carried out in waters adjacent to and in Chinju Bay with the following results. Of the bottles released, $50\~69$ per cent were recovered. 1. The circulation of Chinju Bay is usually caused by the tidal current except during the winter season when the northwest monsoon prevails to cause a wind-drift current. 2. Sea water in the southern part of Chinju Bay flows northward at ebb tide. The ebb current east of the central submarine bank in Chinju Bay flows northeastward toward Samchonpo Channel through the eastern depression of the bank contributing to form a cyclonic eddy. The ebb current west of the bank, however, flows northward toward Noryang Channel through the western depression of the bank. 3. The ebb current nea. the southernmost part of Chinju Bay flows eastward toward Chijok Channel. 4. At flood tide, the main stream of the tidal current in Noryang Channel flows eastward. Turning smoothly to the right, the southern branch of the flood current flows southward through the depression and along the isobaths at the western margin of the central submarine bank, while the northern branch, turning to the left, flows into the Chin-gyo Bay of Hadong. 5. flood current in the eastern area of Kwang-yang Inlet runs northeastward toward Noryang Channel. A small eddy develops near Kwanumpo of Namhae Island. 6. The results suggest that such a drift bottle experiment can be recommended for the attestation of currents, although it is not suitable for a quantitative study of coastal currents.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.325-330
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• 2001

One of the principal components of the KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak structure is the vacuum vessel, which acts as the high vacuum boundary for the plasma and also provides the structural support for internal components. Hyundai Heavy Industries Inc. has performed the engineering design of the vacuum vessel. Here the overall configuration of the KSTAR vacuum vessel was briefly described and then the design methodology and the analysis results were presented. The vacuum vessel consists of double walls, several ports, leaf spring style supports. Double walls are separated by reinforcing ribs and filled with baking/shielding water. The overall external dimensions of the main body are 3.39 m high, 1.11 m inner radius, 2.99 m outer radius, and made of SA240-316LN. The vacuum vessel was designed to be capable of achieving the base pressure of $1\times10^{-8}$ Torr, and also to be structurally capable of sustaining the vacuum pressure, the electromagnetic and thermal loads during plasma disruption and bakeout, respectively. The vacuum vessel will be baked out maximum $150^{\circ}C$ by hot pressurized water through the channels formed between double walls and the reinforcing ribs. A 3-D temperature distribution and the resulting thermal loads in the vessel were calculated during bakeout. It was found that the vacuum vessel and its supports were structurally rigid based on the thermal stress analysis. The maximum electromagnetic loads on the vacuum vessel induced by eddy and halo currents resulting from the engineering plasma radial and vertical disruption scenarios have been estimated. The stress analyses have been performed based on these electromagnetic loads and the resulting stresses at he critical locations of the vacuum vessel were within the allowable stresses.