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Characteristics of magnetic tunnel junctions using amorphous CoSiB free layer
J. Y. Hwang,H. I. Yim,M. Y. Kim,J. R. Rhee,T. W. Kim 한국자기학회 2006 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-
We have investigated the switching properties for MTJs with CoSiB free layer. MTJ with amorphous CoSiB showed lower Hsw with improving sensitivity compared to MTJs with CoFeSiB, CoFe and NiFe free layers because CoSiB had a low Ms and modest Ku. Hint for the CoSiB-based MTJ was further decreased without degrading the sensitivity. It also showed that the V½ of CoSiB-based double MTJ was high enough for high density MRAM.
Yim, S.W.,Park, C.R.,Yu, S.D.,Kim, H.R.,Hyun, O.B.,Sim, J.,Park, K.B.,Oh, I.S. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15
In the first-peak non-limiting type superconductor-triggered fault current limiter (STFCL), which was developed by the collaborative work of KEPRI and LSIS, the first half cycle of fault currents is passed, unlimited. Due to these characteristics, information needed for the fault judgments can be provided to the protection relays, which is useful for the protective coordination of power system. In this fault current limiter, superconductors are used as a fault detector that does not generate resistive loss in normal operation state. Therefore, high J<SUB>c</SUB> and fast occurrence of large resistance are the essential properties of superconductors for the application to fault detectors. In this study, for the design of superconducting fault detector (SFD), we investigated the quench behavior of two kinds of superconductors, stabilizer-free coated conductors (SF-CC) and Au/YBCO/sapphire substrate, during the operation of the first-peak non-limiting type STFCL. The dimension of SF-CC was 12mm widex1000mm long and that of Au/YBCO/sapphire was 20mm widex100mm long. Their critical current (I<SUB>c</SUB>) values were 250A and 200A, respectively, and the critical temperature (T<SUB>c</SUB>) was both 90K for both superconductors. When fault currents of over 3kA were applied, the STFCL carried out the current limitation successfully. At the beginning of the quench, SF-CC generated a resistance of 150mΩ, and 394mΩ was generated in the Au/YBCO/sapphire substrate, when 150V<SUB>rms</SUB> was applied. After the first half cycle, the resistance of the superconductors increased up to 263mΩ, and 846mΩ, respectively, and the temperature reached 132K and 127K. In addition, we also investigated the recovery characteristics of the SFDs. The SF-CC and Au/YBCO/sapphire substrate recovered the superconductivity by 353ms and 357ms, respectively. Based on the results of the analysis, we determined the required length of the superconductors for the SFD application.
박태원(T. W. Park),임홍재(H. J. Yim),이기호(G. H. Lee),박찬종(C. J. Park),정일호(I. H. Jeong) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.11_1
Ride harshness is the important characteristic for a passenger bus. Since ride generally involves frequencies up to 30 Hz, special modelling technique should be used for ride harshness analysis. This paper investigates modelling technique of a passenger bus for ride analysis which involves coupling of rigid bodies and flexible bodies in one model. First step is to build a rigid model and next step is to establish FEM model of a bus body and leaf springs. Then, prepared FEM model is coupled with the rigid model Computational results of the coupled bus model is compared with the testing results. Then, sensitivity analysis was carried out to suggest the direction for the ride quality improvement.<br/> <br/>