Faculty Profiles - KIM Seokbeom

MISC - KIM Seokbeom

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Magnetic-field properties of high critical current density YBCO films deposited by TFA-MOD

SB Kim, S Murase, Y Yamada, T Araki, Hirabayashi, I

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 15 ( 2 ) 2645 - 2648 2005.6

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

The critical current density, J(c), of metal-organic deposition process using trifluoroacetates (TFA-MOD) based YBCO films was measured between 20 K and 77 K in magnetic fields up to 9.5 T as a function of the field direction. C-axis oriented YBCO films was deposited on LaAlO3 single crystalline substrates and also on CeO2 buffered IBAD (YSZ/Hastelloy) substrates by TFA-MOD method. The obtained Jc values at 77 K and 0 T were 7 and 1.7 MA/cm(2) for LaAlO3 and IBAD substrates, respectively. High Jc values over 10(5) A/cm(2) were maintained up to 4 T (B//c-axis) for the LaAlO3 substrate and up to 3 T (B//c-axis) for the CeO2 buffered IBAD substrate. These results imply that TFA-MOD with simple fabrication process is very promising for the practical YBCO coated conductor. And the dependences on temperature and angular of the Jc at various external magnetic fields for some different thicknesses YBCO films was reported.

DOI： 10.1109/TASC.2005.847757

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Effects of Cu stabilizer configuration on thermal stability of Nb3Sn composite superconductors under cryocooling condition

K Watanabe, T Mitsuhashi, N Nanato, SB Kim, S Murase, G Nishijima, K Watanabe, K Miyoshi

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 15 ( 2 ) 3410 - 3413 2005.6

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

It is known that current sharing effects of the stabilizer are limited in cryocooling conditions being different from poolboiling. Therefore we have studied stability under it, focusing on minimum quench energy (MQE) of Nb3Sn superconductors under various conditions of the applied magnetic field, temperature, and the transport current, for various volume fractions and configurations of Cu stabilizer. From the experimental results, the larger the external Cu volume fraction, the higher the MQE was obtained. All MQE data were summarized by only one line in characteristics of normalized MQE and normalized B (B/B-c2). The obtained MQE behavior was to be characterized by only one empirical equation. It is thought that the obtained formula is useful for a standard of designing the Nb3Sn superconductor and its coil under cryocooled condition.

DOI： 10.1109/TASC.2005.848946

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Empirical equation of MQE for Nb_3Sn wires under cryocooling

MITSUHASHII T., WATANABE K., MUASE S., KIM S. B., NANATO N., NISHIJIMA G., WATANABE K.

72 130 - 130 2005.5

Measurement of AC transport current loss for HTS conductors by the active power detection method

OHZAWA T., MURASE S., KIM S. B., NANATO N.

72 2 - 2 2005.5

Time-Frequency Visualization of AE Signal using Wavelet Transform for Precise Measurement and Estimation

NANATO Nozomu, MURASE Satoru, KIM SeokBeom

IEEJ Transactions on Fundamentals and Materials 125 ( 12 ) 1069 - 1070 2005

Language：Japanese Publisher：The Institute of Electrical Engineers of Japan

AE (Acoustic Emission) techniques are universally used for investigating and watching the deformation and crack of various materials because they enable the non-destructive and continuous measurement. However, it is not always easy to clarify the main cause or mechanism of AE signal generation by its analysis and an AE sensor is generally vulnerable to the noise, and therefore advanced measurement and estimation techniques of AE signal are needed. In this paper, the authors present time-frequency visualization of AE signal using the wavelet transform. The proposed method enables especially precise measurement of the frequency band and generation time of AE signal and gives a clue in advanced AE techniques.

DOI： 10.1541/ieejfms.125.1069

CiNii Article

CiNii Books

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Simple Measurement of the AC Transport Current Loss for HTS Conductors Using an Active Power Detection Method

NANATO Nozomu, OHZAWA Toshiaki, MURASE Satoru, KIM SeokBeom

Journal of the Cryogenic Society of Japan 40 ( 10 ) 420 - 424 2005

Development of the protection system of a superconducting coil based on the active power detection method

FUJIWARA Kenji, NANATO Nozomu, MURASE Satoru, KIM Seok Beom

71 56 - 56 2004.11

Effect of thermal hysteresis on residual strain of Cu stabilizer for Cu/Nb_3Sn composite conductors

KIYAMA K., NANATO N., KIM S., MURASE S.

71 91 - 91 2004.11

Pulsed field characteristics of trapped magentic fields for HTS Bulks

NOBUHIRA Atsushi, MURASE Satoru, KIM SeokBeom, NANATO Nozomu, OKAMURA Shingo, INOUE Takuya, MATSUMOTO Yasuaki

69 118 - 118 2003.12

The effect of post-annealing process in NdGaO3 new seed layer for LPE

SB Kim, SI Yoo, Y Yamada

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 392 951 - 955 2003.10

Language：English Publisher：ELSEVIER SCIENCE BV

Novel porous NdGaO3 (NGO) thin film was fabricated as a new seed layer for liquid phase epitaxy growth of YBa2Cu3O7-delta. The microstructure and crystallization mechanism of NGO new seed layer due to post-annealing temperature were revealed by high resolution SEM. Amorphous NGO layers on LaAlO3 single crystalline substrate obtained by pulsed laser deposition method at room temperature and this layer shows the very porous and columnar structure. And this amorphous NGO layers were annealed at wide temperature range below 1300 degreesC in air. Amorphous NGO layer begins to crystallize by post-annealed at 750 degreesC and its orientation gets better with increased annealing temperature. The thickness of NGO layers decrease with increased annealing temperature above 500 degreesC and the well-oriented NGO layers were obtained between 900 and 1300 degreesC. The NGO layers annealed at above 1100 degreesC show very dense film. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0921-4534(03)00862-1

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Microstructure of Nd-Ga-O-3 new seed layer for LPE growth of YBCO film

S Kim, SI Yoo, Y Yamada

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 13 ( 2 ) 2571 - 2574 2003.6

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

The microstructure and crystallization mechanism of NdGaO3 (NGO) new seed layer for liquid phase epitaxy (LPE) growth of YBa2Cu3O7-delta (YBCO) were revealed using high resolution SEM and TEM. NGO layer deposited by PLD at room temperature shows that very porous and columnar structure and this layer indicated amorphous by x-ray analysis. Amorphous NGO layer was crystallized with good in-plane and out of plane orientations keeping columnar structure by simple post annealing process. Biaxially aligned YBCO thick films were successfully fabricated on oriented novel porous NGO new seed layer: Although many cracks were observed for normally LPE grown YBCO films on NGO(110) single crystalline substrate; it was crack-free formed on porous NGO(100) film.

DOI： 10.1109/TASC.2003.811851

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YBa2Cu3O7-delta deposition on Ni-Cr alloy tape by liquid phase epitaxy method

Y Yamada, T Suga, H Kurosaki, SB Kim, T Maeda, Y Yamada, Hirabayashi, I, Y Iijima, K Kakimoto, T Saitoh

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 378 971 - 974 2002.10

Language：English Publisher：ELSEVIER SCIENCE BV

Thick YBa2Cu3O7-delta (YBCO) films have been successfully formed by the liquid phase epitaxy (LPE) method on Ni-Cr alloy tape. A buffer layer of yttria stabilized zirconia and seed layer of YBCO were formed by the ion beam assisted deposition and by the pulsed laser deposition method, respectively. YBCO films have been grown from the solution of BaO-CuO-Ag-BaF2 at 820, 845 and 860 degreesC under low oxygen partial pressure of 2% to prevent the metallic substrate from reacting with the solution. Good YBCO films are obtained by the growth at 820 degreesC, and the best one shows high critical current density of 1.9 MA/cm(2). A cross-sectional observation by high resolution scanning electron microscopy shows neither reaction layer nor damaged region at the substrate[YBCO film interface. theta-2theta and pole figure X-ray diffraction of the seed layer and the YBCO LPE layer show that in-plane orientation distribution is highly improved by the LPE process. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0921-4534(02)01579-4

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YBCO films formed on a Ni-base alloy tape by the low temperature Liquid phase epitaxy method

YAMADA Yasji, KIM S. B., SUGA T., YAMADA Yutaka, HIRABAYASHI I., IIJIMA Y., KAKIMOTO K., SAITOH T.

65 17 - 17 2001.11

Superconducting properties of YBCO films formed by the low temperature Liquid phase epitaxy method

YAMADA Yasji, KIM S. B., SUGA T., YAMADA Yutaka, HIRABAYASHI I.

65 88 - 88 2001.11

YBCO thin films on multilayers prepared by all-chemical solution deposition processing

H. Hiei, K. Yamagiwa, Y. Takahashi, S. B. Kim, Y. Yamada, J. Shibata, T. Hirayama, H. Ikuta, I. Hirabayashi, U. Mizutani

Physica C: Superconductivity and its Applications 357-360 ( 1 ) 942 - 945 2001.9

Language：English

The chemical solution deposition (CSD) technique has been applied to prepare both YBa2Cu3O7-δ (YBCO) and buffer layers on a YSZ substrate. Y2O3 and CeO2 were employed as the buffer layers, and it was confirmed that they grew epitaxially by the CSD method. Cross-sectional transmission electron microscope observations revealed that Y2O3 grew up to the top of the film. Furthermore, the YBCO film on the Y2O3 or CeO2/Y2O3 layers were c-axis aligned and showed a good in-plane alignment. The transition temperature and the critical current density of the YBCO/Y2O3/YSZ multilayer were 89 K and 4 × 104 A/cm2 at 77 K, 0 T, respectively. © 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0921-4534(01)00448-8

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Critical current density and related microstructures of TFA-MOD YBCO coated conductors

Y Yamada, S Kim, T Araki, Y Takahashi, T Yuasa, H Kurosaki, Hirabayashi, I, Y Iijima, K Takeda

PHYSICA C 357 1007 - 1010 2001.8

Language：English Publisher：ELSEVIER SCIENCE BV

Metalorganic deposition process using trifluoroacetate (TFA-MOD) processed YBCO film on LaAlO3 and IBAD (YSZ/Hastelloy) substrate exhibited high critical current density, J(c), at 77.3 K. The obtained J(c) values at 0 T were 7 and 1.7 MA/cm(2) for LaAlO3 and CeO2 buffered IBAD, respectively. High J(c) values over 10(5) A/cm(2) were maintained up to 4 T (B parallel toc-axis) for the LaAlO3 substrate and up to 3 T (B parallel toc-axis) for the CeO2 buffered IBAD substrate. These results imply that TFA-MOD with simple fabrication process is very promising for the practical YBCO coated conductor. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0921-4534(01)00471-3

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Superconducting properties of YBCO films formed by the Liquid phase epitaxy method

YAMADA Yasji, KIM S. B., SUGA T., YAMADA Yutaka, HIRABAYASHI I., IIJIMA Y., KAKIMOTO K., SAITOH T.

64 20 - 20 2001.5

Lowering of LPE growth temperature for YBCO formation on metal tapes

SUGA T., YAMADA Y., KIM S. B., MAEDA T., YAMADA Y., HIRABAYASHI I., YOSHINO H., YAMAZAKI M., THANH T. D.

64 19 - 19 2001.5

Low-temperature liquid-phase epitaxial growth of YBa_2Cu_3O<7-δ> on NiO-buffered textured-Ni tapes

MAEDA Toshihiko, KUROSAKI Haruhiko, SUGA Toshihiro, KIM SeokBeom, YAMADA Yasuji, WATANABE Tomonori, HIRABAYASHI Izumi

64 21 - 21 2001.5

Fabrication of new seed layer for LPE growth of YBCO superconducting wires

KIM S. B., YAMADA Yasuji, SUGA T., MAEDA T., YAMADA Yutaka, WATANABE T., HIRABAYASHI I.

64 112 - 112 2001.5

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