• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1998-1999
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• 2007

Before applying the HTS(High Temperature Superconductor) power devices to a real utility network, system analysis should be carried out by some simulation tools. PSCAD/EMTDC simulation tool is one of the most popularized useful analysis tools for electrical power system. Unfortunately the model component for HTS coil is not provided in PSCAD/EMTDC simulation tool. In this paper, EMTDC model component for HTS coil has been developed considering real characteristics of HTS coil like critical current, temperature and magnetic field. The developed model component of HTS coil could be used for power system application. Using the developed model component for HTS coil, we can easily do the simulation of HTS power devices application test in utility with the various inductance, quench current, inner magnetic field, and temperature values, for instances; SMES(Superconducting Magnetic Energy Storage) system, superconducting motor, transformer, and FCL(Fault Current Limiter)

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.231-236
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• 2000

In order to predict depth of the pile forward modeling and inversion of magnetic logging data was conducted by using a finite line of dipoles model. The horizontal component as well as the vertical component of magnetic fields can be measured in the borehole, and the magnetic anomalies can be obtained by subtracting the Earth's magnetic field from the measurement. The magnetic anomalies of the pile are considered as vector sum of induced magnetization due to the Earth's magnetic field and remnant magnetization possessed by steel strings in the pile. The magnetic anomalies are used as input data for inversion from which the length, the magnetic moment per unit length, and the dip angle of the pile can be obtained. From the inversion of synthetic noisy data, and the data obtained from the field model test it is found that the driving depth of the pile can be determined as close to the order of measuring interval (5∼10㎝). It is also found that the resultant magnetic anomalies due to an individual steel string in the pile are almost same as those due to a group of steel strings located at the center of the pile. The magnetic logging method also can be used for locating reinforced bars, pipes, and steel casings.

• Journal of Biomedical Engineering Research
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• v.25 no.3
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• pp.183-188
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• 2004

Magnetic resonance current density imaging (MRCDI) is a useful method for measuring electrical current density distribution inside an object. To avoid object rotations during the conventional MRCDI scans, we have reconstructed current density component images by applying a spatial filter to the magnetic field data measured both inside and outside the object. To measure the magnetic field outside the object with MRI, we immersed the object in a water tank. To evaluate accuracy of the current density imaging, we have made a conductivity phantom with a corresponding finite element method model. We have compared the experimentally obtained current density images with the ones calculated by the finite element method. The average errors of the reconstructed current density images were 6.6 ∼ 45.4 ％ when the injected currents were 1 ∼ 24 mA. We expect that the current density component imaging technique can be used in diverse biomedical applications such as electrical therapy system developments and biological electrical safety analysis.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.97-101
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• 2003

When HTS tapes are used in power application, they are used by winding form, such as, a pancake and a solenoid. When AC current is applied to the coil, Ac magnetic field is generated in winding. This AC magnetic field acts as an external magnetic field and makes loss. In this paper the radial magnetic field component ($B_r$) and the axial magnetic field component ($B_z$) in a pancake and a solenoid were calculated by numerical analysis method and compare with measured value. AC losses of a short sample were calculated by Norris equation and n numerical analysis based on Brandt equation. AC losses of the pancake coil and the solenoid coil were also calculated.

• Journal of the Korean Geophysical Society
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• v.2 no.2
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• pp.135-142
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• 1999

Interpretations of 3-component magnetic logging data obtained for a reinforced bar as a model of the line of the magnetic dipoles are conducted using a least squared inversion technique. The length of the bar is 1.12 m, sampling interval is 0.05 m, the distance between the bar and the borehole is 0.3 m, and the top of the bar is fixed at 0 m of depth. The bar is set to be approximately vertical. Magnetic anomalies smoothed with FFT are used as input data for the inversion. For the interpretation of magnetic logging data the depth to the top, the length, the magnetic moment per unit length, the direction of the magnetization (declination and inclination), and the bearing and plunge of the line of magnetic dipoles are left as unknown parameters. The comparison of the results obtained from the individual inversion of the horizontal component or the vertical component of the magnetic anomalies, and those from the simultaneous inversion of horizontal and vertical component of the magnetic anomalies shows that there exist some disagreements between each inversion result. The depth to the bottom of the bar, which is actually 1.12 m, is estimated as 1.18 m, and the inclination of the magnetization is estimated as -76°by simultaneous inversion. The negative value of the inclination indicates that the strength of the remnant magnetization is much greater than that of the induced magnetization, so that the direction of the resultant magnetization points to the top of the bar.

• Investigative Magnetic Resonance Imaging
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• v.21 no.4
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• pp.252-258
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• 2017

Primary mesenteric liposarcoma is rare. It is difficult to make an accurate preoperative diagnosis of the myxoid type of liposarcoma by using imaging such as ultrasound or computed tomography (CT) due to the very small amount of fat that is located in the tumor. We report a case of primary myxoid liposarcoma of the mesentery which was difficult to differentiate from other solid mesenteric tumors with a myxoid component such as low grade fibromyxoid sarcoma, myxoid leiomyosarcoma or myxoma. Use of chemical shift magnetic resonance (MR) imaging to detect small fat components and its cystic appearance with solid components on the MR images can be useful to differentiate myxoid liposarcoma from the other mesenteric tumors with a myxoid component.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1106-1107
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• 2007

Planar magnetic based design technologies have been widely applied to power design for better cooling and ease of fabrication. The planar transformer and the planar inductor have a low profile characteristics compare to the conventional transformer which would be more cubical in volume. High frequency operation of magnetic components is a main key to achieve high power density of the power module. However, at a high frequency, the skin effect and the proximity effect have to be considered very significantly in magnetic design and also the parasitics in the converter cannot be ignored. This paper deals with the design and the experiment of planar integrated magnetic component. The optimal design for planar magnetics is summarized.

• Journal of the Korean Magnetic Resonance Society
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• v.16 no.2
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• pp.133-146
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• 2012

Three different derivatives were obtained in the synthesis of cobalt-binding BLM-A2 and characterized by NMR and Mass spectrometry. It was found that Component 1 is Co(II)($2H_2O$)(BLM-A2), component 2 is Co(III)($OOH^-$)(BLM-A2) and component 3 is Co(III)($H_2O$)($OH^-$)(BLM-A2), respectively. Component 2 and 3 were interestingly dominated when CoBLM-A2 complex was synthesized under basic condition. In this experiment, it was revealed newly that the brown form (component 1) was 6-coordinated structure composed with not 5 ligands but 4 ligands from BLM-A2 and with $2H_2O$ as the axial ligands. The component 3 exhibiting a novel ligand configuration is found, and the structure of component 3 was observed to be very similar to that of component 1 in the kind of their ligands but one of the axial ligand is $OH^-$ instead of $H_2O$. These ligand configurations are different from the green form (component 2) exhibiting 6-coordinate structure composed of 5 ligands from BLM-A2 and one ligand of $OOH^-$, being consistent with former studies.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1942-1946
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• 2009

This paper presents a shape design process of Claw-Poles Stepping Motor(CPSM) using Modified Magnetic Equivalent Circuit Method(MMEC). Because this motor is adopted on low power devices, the motor size is a very small type. But it have a very strong permanent magnet. So magnetic saturation effect happens on yoke teeth of CPSM. Also this magnetic saturation effect causes more leakage flux component between yoke tooth have another pole. In this motor type, it is essential to design a shape of yoke teeth for avoiding the magnetic saturation effect and the leakage flux. In this paper, MMEC including the magnetic saturation effect and the leakage flux component was used for design process. Comparing with data calculated by using the MMEC and results analyzed by 3-D FEM, it could be stated that the design process with MMEC was reasonable. Finally, the model has the optimized shape of yoke teeth was compared with a conventional model for no-load Back EMF and torque at steady-state operation.

• Geophysics and Geophysical Exploration
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• v.27 no.2
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• pp.119-128
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• 2024

Marine magnetic surveys provide a rapid and cost-effective method for pioneer geophysical survey for many purposes. Sea-surface magnetometers offer high accuracy but are limited to measuring the scalar total magnetic field and require dedicated cruise missions. Shipboard three-component magnetometers, on the other hand, can collect vector three components and applicable to any cruise missions. However, correcting for the ship's magnetic field, particularly viscous magnetization, still remains a challenge. This study proposes a new additional correction method for ship's viscous magnetization effect in vector data acquired by shipboard three-component magnetometer. This method utilizes magnetic data collected simultaneously with a sea-surface magnetometer providing total magnetic field measurements. Our method significantly reduces deviations between the two datasets, resulting in corrected vector anomalies with errors as low as 7-25 nT. These tiny errors are possibly caused by the vector magnetic anomaly and its related viscous magnetization. This method is expected to significantly improve the accuracy of shipborne magnetic surveys by providing corrected vector components. This will enhance magnetic interpretations and might be useful for understanding plate tectonics, geological structures, hydrothermal deposits, and more.