Faculty Profiles - KIM Seokbeom

MISC - KIM Seokbeom

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The study on optimization issues for magnetic separation by magnetic chromatography

S. B. Kim, R. Iwamoto, K. Kataoka, S. Noguchi, H. Okada

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 470 ( 20 ) 1804 - 1807 2010.11

Language：English Publisher：ELSEVIER SCIENCE BV

The magnetic chromatography is a very useful system for an ion and/or fine magnetic particle separation because it has strong magnetic field gradients even in a very narrow flow channel. We have not only developed the magnetic chromatography system to separate the fine particles and ions, but also the numerical analysis code based on the fluid dynamics and electromagnetism to investigate the separating characteristics and to optimize design of magnetic column. In this study, the simple experiments using a superconducting magnet with a large room-temperature-bore and a micro-scale magnetic column consisting of ferromagnetic wires were carried out to understand the ions separation. The cobalt chloride (CoCl(2)) and the nickel sulfate (NiSO(4)) were used as ions, and the magnetic field and length of magnetic column were used as a parameter in an experiment and an analysis. It can be expected that the ion mobility of a single and complex are quite different, and the ability of the separation will be improved by increasing the column length without external magnetic field. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physc.2010.05.211

Quench protection technique for HTS coils with electronic workbench

J. H. Joo, S. B. Kim, T. Kadota, H. Sano, S. Murase, H. M. Kim, Y. K. Kwon, Y. S. Jo

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 470 ( 20 ) 1874 - 1879 2010.11

Language：English Publisher：ELSEVIER SCIENCE BV

The stability and the protection of superconducting applications are very important issues. High temperature superconductor (HTS) is stable than low temperature superconductor (LTS). However, due to the high stability of HIS, HIS coils have complicate behaviors of normal transition - such as a recovery into the superconducting state or thermal runaway - which is determined by the magnitude of disturbance, coil size, the structure of winding wire and cooling condition. In this paper, we propose the quench protection system based on the active power method which can detect the quench by measuring the generating instantaneous active power in HTS coils. And the quench detection circuit adopted a software circuit by LabVIEW which was added a new quench protection technique to the circuit in order to improve its detection performance. Furthermore, it can monitor interior states of HIS coils with acquiring the only coil voltages in real time. To confirm the validity of the suggested technique, the experiments were performed with the hardware circuit for quench detection simultaneously. The experimental results are presented and discussed in this paper. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physc.2010.05.226

Trapped Field Characteristics of Stacked YBCO Thin Plates for Compact NMR Magnets: Spatial Field Distribution and Temporal Stability

Seungyong Hahn, Seok Beom Kim, Min Cheol Ahn, John Voccio, Juan Bascunan, Yukikazu Iwasa

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 20 ( 3 ) 1037 - 1040 2010.6

Language：English Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

This paper presents experimental and analytical results of trapped field characteristics of a stack of square YBCO thin film plates for compact NMR magnets. Each YBCO plate, 40mm X 40 mm x 0.08 mm, has a 25-mm diameter hole at its center. A total of 500 stacked plates were used to build a 40-mm long magnet. Its trapped field, in a bath of liquid nitrogen, was measured for spatial field distribution and temporal stability. Comparison of measured and analytical results is presented: the effects on trapped field characteristics of the unsaturated nickel substrate and the non-uniform current distribution in the YBCO plate are discussed.

DOI： 10.1109/TASC.2010.2043832

Development of Numerical Analysis Method for Magnetic Separation of Magnetic Particle and Ion With Magnetic Chromatography

So Noguchi, SeokBeom Kim, Katuhito Kataoka

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 20 ( 3 ) 961 - 964 2010.6

Language：English Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

The magnetic chromatography is a very useful system for an ion and/or fine magnetic particle separation due to its strong magnetic field gradients in a very small flow channel. We have developed the magnetic chromatography system to separate the fine particles and ions. However, its numerical simulation is difficult, since the scale of the ions or fine particles in fluid is much different from the scale of the superconducting magnet generating the strong magnetic field. In order to accurately simulate the magnetic separation, it is necessary to develop the simulation code dealing with the multi-scale problem.

DOI： 10.1109/TASC.2009.2039928

Study on Quench Protection Method With Regards to Normal Transition Behavior for HTS Coil

J. -H. Joo, H. Sano, T. Kadota, S. -B. Kim, S. Murase, Y. -K. Kwon, H. -M. Kim, Y. -S. Jo

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 20 ( 3 ) 2027 - 2030 2010.6

Language：English Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

This paper presents the quench detection method with using normal transition behavior for HTS coil. If the HTS coil starts to propagate a normal zone by an initial quench, it will be recovered the superconducting state or runaway thermally. These behaviors were mainly determined by variety parameters like the magnitude of a disturbance, HTS coil size, the structure of winding wire and cooling condition. However, the first step of detection or protection for coils should be started from detecting the presence of a non-recovering normal zone. This paper classifies the initial quench behaviors of HTS wires or coils as a model of 3-type tendencies, and suggests suitable detection techniques for each tendency with using the end-to-end voltage of coil. In additional, this method is able to detect a quench without a decisive criterion used at other quench detection methods. In order to confirm the validity of the method, we used the HTS sample coil wound with YBCO tapes. This paper presents these results and the quench protection properties with fabricated detection method.

DOI： 10.1109/TASC.2010.2043238

The Characteristics of the Normal Transition in the Longitudinal and Transverse Directions in Cryocooled YBCO Coils

S. -B. Kim, H. Sano, J. -H. Joo, T. Kadota, S. Murase, H. -M. Kim, Y. -S. Jo, Y. -K. Kwon

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 20 ( 3 ) 2078 - 2082 2010.6

Language：English Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Recently, the superconducting devices using cryogenic and superconducting technologies were widespread in the field of electric power. The 2G wires with YBCO superconducting layer, metal substrate and stabilizer layer are expected to be used in future superconducting applications, because it has high properties in high temperature and high magnetic fields. In order to operate safely at high transport currents, the thermal stability of the wounding wire should be addressed in terms of detection and protection against the quench. On the other hand, the understanding of the 3-dimensional normal zone expansion during a quench is very important to design the superconducting devices such as magnets and cables. This paper presents the results of an experimental study for normal zone propagation properties in the longitudinal and transverse directions using the pancake coil wound with 2G wires which have Cu and SUS stabilizers under the cryocooler cooling. And the minimum quench energy (MQE) of the pancake coils wound with two different kinds of stabilizers as functions of operating temperature and transport current will be described.

DOI： 10.1109/TASC.2010.2044652

Development of numerical simulation method for magnetic separation of magnetic particles

So Noguchi, SeokBeom Kim

Digests of the 2010 14th Biennial IEEE Conference on Electromagnetic Field Computation, CEFC 2010 2010

Language：English

The magnetic separation is a very useful tool to manufacture medicine. We have developed the magnetic chromatography system, which separates the magnetic particles or the ions from fluid due to its strong magnetic field gradients in a very small flow channel. In order to simulate the magnetic separation, we developed the simulation code dealing with the multi-scale problem, and verified the results compared with the experimental ones. © 2010 IEEE.

DOI： 10.1109/CEFC.2010.5481745

The effects of the shape of the 2-D arranged electromagnets on levitation performances of the 3-D superconducting actuator

OKUGAWA Keisuke, KIM SeokBeom, JOO JIN-HONG, INOUE Daiji, UWANI Youhei, MURASE Satoru

81 187 - 187 2009.11

Development of compact NMR magnets with stacked HTS bulks and films

KIM S. B., TAKANO R., IMAI M., HAHN S. Y., IWASA Y., JOHN V.

81 114 - 114 2009.11

Development of the compact NMR magnet using stacked HTS bulks

TAKANO Riki, IMAI Makoto, KIM SeokBeom

81 113 - 113 2009.11

Characteristics of the magnetic field distribution on compact NMR magnets using cryocooled HTS bulks

S. B. Kim, R. Takano, T. Nakano, M. Imai, S. Y. Hahn

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 469 ( 15-20 ) 1811 - 1815 2009.8

Language：English Publisher：ELSEVIER SCIENCE BV

Recently, the performance of high temperature superconducting (HTS) bulks such as critical current density, size, and mechanical strength has been improved rapidly. So. various applications using HTS bulks such as motors, bearings and flywheels have been investigated by many research groups. A compact nuclear magnetic resonance (NMR) magnet is one of the new applications after a technique to enhance maximum trapped field of the HTS bulk more than 11.7 T (500 MHz (1)H NMR frequency) has been developed.
This new compact NMR magnet out of HTS bulks is cost-effective compared with conventional NMR magnets and then expected to be widely used in food and drug industry. In design and manufacture of the compact NMR magnets, spatial field homogeneity of the large trapped magnetic field in HTS bulk annuli is a crucial issue because the behavior of a trapped field is highly non-linear and, as a result, a technique to improve the field homogeneity such as active/passive shimming now becomes more challenging compared with that of the conventional counterparts.
This paper presents the magnetic field distributions in single and three assembled HTS bulk annuli measured by a 3-axis and multi-arrayed Hall sensor under two different cryogenic environments: (I) in a bath of liquid nitrogen (LN(2)) and (2) dry cooling by a cryocooler. The spatial homogeneity changes with various operating temperatures were investigated and the effect of critical current density enhancement by lowering the operating temperature on the field homogeneity improvement was discussed in detail. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physc.2009.05.161

Effect of the hot pressing on the magnetic-field and temperature dependences of flux pinning for SiC-doped MgB2 tape

H. Kuwashima, N. Nanato, S. B. Kim, S. Murase, Y. Yamada, A. Nitta, K. Tachikawa, G. Nishijima, K. Watanabe

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 469 ( 15-20 ) 1515 - 1518 2009.8

Language：English Publisher：ELSEVIER SCIENCE BV

To understand the effects of the hot pressing on the pinning behavior for the SiC doped MgB2 tape wire, magnetic field and temperature dependences on a critical current density J(c) and the pinning force have been studied. The MgB2 tapes were fabricated using an in situ powder-in-tube (PIT) method, the hot pressing process with nano-SiC powders and the carbon steel sheath. J(c) of the hot pressing processed wire is enhanced especially at low field compared with that of the no hot-pressed wire. It is suggested that the enhancement of J(c) is caused by the improvement of the MgB2 grain connectivity came from the hot pressing.
The pinning analysis using the pinning models of a surface pinning and a normal point pinning lead to that the scaled curve of the pinning force for the SiC-doped MgB2 tape with the hot pressing process showed anisotropy in a lower field. This result suggests that the pinning center of the hot pressing processed MgB2 wire forms into inequi-axial shape, which is different from that in the tape without the hot pressing having the equi-axial pinning center in our previous report. It was also found that the scaled pinning force of the SiC-doped MgB2 tape with the hot pressing is larger than the surface pinning model in a higher field. This suggests that the pinning force was enhanced by the hot pressing in a higher field. (C) 2009 Published by Elsevier B.V.

DOI： 10.1016/j.physc.2009.05.231

Characteristics of Magnetic Separation for Magnetic Particle and Ion by Magnetic Chromatography With Novel Magnetic Column

SeokBeom Kim, Yuichi Okimoto, Satoru Murase, So Noguchi, Hidehiko Okada

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 19 ( 3 ) 2152 - 2156 2009.6

Language：English Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

The magnetic chromatography (MC) is a very useful system for an ion and/or fine magnetic particle separation due to its strong magnetic field gradients in a very small flow channel. We have not only developed the MC system to separate the fine particles and ions, we have also developed the numerical analysis computer code based on the fluid dynamics and electromagnetism to investigate the separating characteristics and to optimize design of magnetic column. In this paper, we studied MC technology for magnetic particles and ion separations using micro-scale magnetic column with ferromagnetic wires experimentally. The influences of the strength of magnetic gradient, flow velocity and coefficient of viscosity of solvent were studied by the developed computer code.

DOI： 10.1109/TASC.2009.2019143

Development of Quench Detection Method Based on Normal Transition Behaviors for HTS Coils

Jin-Hong Joo, Hayato Sano, Seok Beom Kim, Satoru Murase, Young Kil Kwon, Ho Min Kim

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 19 ( 3 ) 2415 - 2418 2009.6

Language：English Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Recently, the superconducting devices using cryogenic and superconducting technologies were widespread in the field of electric powers. The quench protection is one of the important issues for safety operating of the superconducting devices, because the excessive joule heating brings about damage to the superconducting magnets when the quench occurs. However, if the HTS coil starts to transit normally by an initial quench, it will be recovered into the superconducting state or runaway thermally. These behaviors were mainly determined by the magnitude of a disturbance, HTS coil size, the structure of winding wire and cooling condition. Therefore, in order to detect the transition into the normal state at HTS coil more accurately, it needs to investigate these effects as parameters. This paper describes the electromagnetic and thermal behaviors of HTS during normal transition by the initial quench. The aim is the development of the quench detection method about HTS coil for 5 MW HTS motor after an initial quench. It adopted the hardware and the software that were able to estimate the quench by monitoring the voltage and temperature for the behavior between the thermal runaway and the recovery. This paper will be presented these results and the quench protection properties with fabricated detection method.

DOI： 10.1109/TASC.2009.2017695

Quench and Normal Zone Propagation Characteristics of RHQT-Processed Nb3Al Wires Under Cryocooler-Cooling Conditions

Satoru Murase, M. Shimoyama, N. Nanato, S. B. Kim, G. Nishijima, K. Watanabe, A. Kikuchi, N. Banno, T. Takeuchi

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 19 ( 3 ) 2666 - 2669 2009.6

Language：English Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

The minimum quench energy (MQE) and normal zone propagation velocity (NZPV) of three kinds of Nb3Al superconductors fabricated by the rapid heating, quenching and transformation (RHQT) process were measured under various conditions of applied magnetic field (10-14 T), temperature (7-11 K), and transport current (80-95% of the critical current), while cooled by a cryocooler for developing the over 20-T class cryogen-free magnet. As a result, MQE values were related to the critical current density (J(c)); high MQE was obtained for low J(c). It is assumed that J(c) has a stronger influence on the MQE than specific heat, thermal conductivity, resistivity, and other parameters of the composite superconductor including the matrix and the stabilizer. NZPV was mainly proportional to the transport current density varying with applied field and temperature. The second contribution to NZPV is assumed to be heat capacity depending on the wire configuration.

DOI： 10.1109/TASC.2009.2018149

Study on Trapped Field Characteristics of HTS Bulk Annuli With Iron Rings for Ferromagnetic Shimming of a Compact NMR Magnet

SeokBeom Kim, Toshiya Nakano, Riki Takano, Seung-yong Hahn

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 19 ( 3 ) 2273 - 2276 2009.6

Language：English Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Recently, the performance of high temperature superconducting (HTS) bulks such as critical current density, size, and mechanical strength has been improved rapidly. So, various applications with HTS bulks such as motors, bearings, and flywheels have been investigated by many research groups. A compact nuclear magnetic resonance (NMR) magnet is one of the new applications after the technique to enhance maximum trapped field of the HTS bulk more than 11.74 T, a corresponding NMR frequency of 500 MHz, has been developed. This new compact NMR magnet out of HTS bulks is far less expensive than those conventional NMR magnets and expected to be widely used in food and drug industry. In design and manufacture of those compact NMR magnets, spatial field homogeneity of large trapped magnetic field in HTS bulk annuli is essential. This paper presents the magnetic field distribution in single and three assembled HTS bulk annuli, measured by a 3-axis hall sensor, and experimental results of its spatial homogeneity improvement by mounting an iron ring inside or outside of the HTS bulk annuli.

DOI： 10.1109/TASC.2009.2019083

Investigation of separation phenomenon for ultra-fine particle by magnetic chromatography method (part III)

KATAOKA K., IWAMOTO R., KIM S. B., MURASE S., NOGUCHI S., OKADA H.

80 170 - 170 2009.5

Transport characteristics of meander and bispiral types resistive fault current limiters

S. B. Kim, M. Nishimoto, J. H. Joo, S. Murase

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 468 ( 15-20 ) 2059 - 2062 2008.9

Language：English Publisher：ELSEVIER SCIENCE BV

The resistive type fault current limiter based on YBCO thin film with high critical current density was proposed and developed because of its fast recovery characteristics. We have been developing a magnetic field measurement system with hall sensor to study the critical Current density distribution or magnetic properties of high-T-c superconductors such as thin film, tape conductor and coated conductors. In this study, the transport current distribution in straight line and U-corner region of meander type resistive fault current limiter using YBCO thin film was investigated experimentally. The both axial and radial self-magnetic field components according to the direct (DC) and alternating (AC) transport currents were measured by two-axis hall probe to estimate the current distribution. And also, the self-magnetic field at the corner of bispiral type fault current limiter was measured by two-axis hall probe with a high spatial resolution to compare with the meander type fault Current limiter. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physc.2008.05.264

J(c) anisotropy and pinning behaviors of the in-situ MgB2 wires with/without SiC addition

Hideyuki Kuwashima, Satoru Murase, Nozomu Nanato, Seok-Beom Kim, Yutaka Yamada, Akio Nitta, Kyoji Tachikawa

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 18 ( 2 ) 1212 - 1215 2008.6

Language：English Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

In an attempt to understand the effects of SiC addition on the pinning behavior for the in-situ PIT MgB2 tape wire, field and temperature dependencies on critical current density, J(c) and the pinning force were studied by considering applied magnetic field direction for the rectangular-shaped wire. As a result, it was clarified that the SiC-doped wire has the equiaxial pinning center and the un-doped wire has the inequi-axial pining center. Taking the pinning scaling law into account, it is found that the SiG-doped MgB2 wire has two kinds of the pinning center and the dominant pinning center changes with temperature, that is, the pinning centers are the grain boundary and the precipitates at high and low temperatures, respectively. The un-doped MgB2 wire is assumed to have anisotropy of the pinning mechanism.

DOI： 10.1109/TASC.2008.921871

Magnetic-field and temperature dependencies of flux pinning for SiC doped MgB_2 tape wire with hot pressing

KUWASHIMA H., NANATO N., KIM S. B., MURASE S., YAMADA Y., NITTA A., TACHIKAWA K., NISHIJIMA G., WATANABE K.

78 134 - 134 2008.5

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