ITE Technical Report
Online ISSN : 2424-1970
Print ISSN : 1342-6893
ISSN-L : 1342-6893
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33.22
Displaying 1-17 of 17 articles from this issue
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  • [title in Japanese]
    Article type: Cover
    Pages Cover1-
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_Cover1
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • [title in Japanese]
    Article type: Index
    Pages Toc1-
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_Toc1
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • Possibility of Increasing Recording Density in Epitaxial Perpendicular Magnetic Recording Media
    Kazuhiko SHINTAKU, Saori WATANABE
    Article type: Article
    Session ID: MMS2009-35
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_1
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Due to CoPt-TiO_2 granular-type media prepared on a highly oriented high-B_s FeCo soft underlayer pinned by an IrMn antiferromagnetic layer, the minimum Ru intermediate layer thickness was reduced down to 1nm. The size of CoPt grains segregated by TiO_2 was about 5nm in diameter. These results satisfy the conditions for high-density magnetic recording. It is important to develop a means to reduce the medium noise due to the improvement of soft underlayer.
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  • Uniaxial magnetocrystalline anisotropy for c-plane oriented Co_<100-x>Ge_x film with pseudo-hcp structure
    Shintaro HINATA, Shin SAITO, Ryuichi YANAGISAWA, Migaku TAKAHASHI
    Article type: Article
    Session ID: MMS2009-36
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_5
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Effects of Ge addition into Co sputtered film on uniaxial magnetocrystalline anisotropy energy (K_u) were investigated. Through the quantitative evaluation of degree of stacking faults using laboratory-scale in-plane XRD, it was found that; (1) c-plane-oriented pseudo-hcp structure was formed in CoGe alloy films sputtered on Ru underlayer in the Ge composition less than 21at.%. (2) Saturation magnetization was monotonously decreased with increasing Ge content, while K_u took the maximum value of 6.3×10^6erg/cm^3 at Ge content of 10at%. (3) -A-B-C-stacking probability, P_<fcc>, showed 10% for pure Co film, while, 1% for Co_<90>Ge_<10> film. (4) Ge addition was found to eliminate stacking faults in Co-based magnetic grains, which was one reason of the enhancement of K_u for CoGe alloy films.
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  • Simulation of High Density Recording for Bit Patterned Media with Weakly Inclined Anisotropy Using Shielded Planar Head
    Naoki HONDA, Kiyoshi YAMAKAWA, Kazuhiro OUCHI
    Article type: Article
    Session ID: MMS2009-37
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_9
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Recording properties of bit patterned media with 60-deg. weakly inclined anisotropy were studied by simulation. When a shielded planar head was used, a recording system with an areal density of 2.6Tbit/in^2 is expected with introduction of weakly inclined anisotropy. However, a small dispersion of less than 4% in the anisotropy field and an orientation dispersion of less than 7 degree would be required. Possibility of a recording system with a density of 4Tbit/in^2 was also obtained when additional exchange coupling between the dots was introduced based on an extremely narrow distribution in the anisotropy field.
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  • Consideration to Data Storage as Green IT and Data Management in the near future
    Shinobu FUJIHARA
    Article type: Article
    Session ID: MMS2009-38
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_15
    CONFERENCE PROCEEDINGS FREE ACCESS
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    The saturation of information services creates huge size of data every day. The growth of data needs expansion of storage systems, which keeps increasing the electric power for their operations and cooling. On the other hand, the saturation changes business work flows. Especially, the file-based information that has been preserved in videotape or chemical film needs consideration to long term digital preservation in addition to greenness. This report describes metrics in consideration of the storage power utilization and approaches to the long term digital preservation.
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  • Tiered Storage Architecture and Tiering Management Method for Saving Energy Consumption of High-Speed Mass Storage in HPC Systems
    Hirotoshi Akaike, Kazuhisa Fujimoto, Naoya Okada, Kenji Miura, Hiroaki ...
    Article type: Article
    Session ID: MMS2009-39
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_21
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Recently, energy consumption of IT devices including storage systems is extraordinarily increasing, and it has become a serious problem. In this paper, we propose a tiered storage method with an access prediction for saving energy consumption of high-speed mass storages in HPC systems. A high-speed mass storage with our proposed method consists of high-speed online storages (OL) and large nearline storages (NL). All data are always stored in NL. Before job execution, only the files accessed by HPC Systems are migrated from NL to OL. In order to save energy consumption, NL disks are usually powered off and on only while data migration. Our method predicts when and which job is executed and files are accessed based on job scheduling to manage data migration.
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  • Research of access prediction control method for high speed mass storage system for HPC
    Naoya OKADA, Kazuhisa FUJIMOTO, Hirotoshi AKAIKE, Kenji MIURA, Hiroaki ...
    Article type: Article
    Session ID: MMS2009-40
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_27
    CONFERENCE PROCEEDINGS FREE ACCESS
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    These days, high speed and high efficiency mass storage systems are strongly needed. We propose a new tiered storage system architecture and a new control method applied queuing theory for HPC. The job waiting time is given by a queuing theory calculation with job queue information from a job scheduler. Data migration between high-speed online storage and massive nearline storage and power control of HDD are performed according to an access prediction algorithm. In this paper, we discuss the evaluation of access prediction probability when managing a job queue.
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  • Analysis of track-edge noise from viewpoint of write heads with different dimensions
    Yosuke Urakami, Naoto Ito, Hiroyuki Katada, Masato Shiimoto, Sarbanoo ...
    Article type: Article
    Session ID: MMS2009-41
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_33
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Track-edge noise, which is one of the major hindrances in achieving the narrow track recording, was studied through the spinstandtesting and the micromagnetics simulations. Three heads with different write pole widths were carefully chosen in the experiments so that their on-track head field gradients were almost similar, and the recording performance of these heads was evaluated with an identical narrow read head. Despite of their similar on-track field gradients, the narrowest write head exhibited significantly a low signal-to-noise ratio (SNR) at the track center. The reason for this is that the skirt of the reader sensitivity function contributed to an increase in noise even when the reader was at the center of the track. This experimentally observed track-edge noise effect on the ontrack SNR was also confirmed through the micromagnetics simulations. The simulation results revealed that increasing the cross-track head field gradient effectively reducing the track-edge noise. A wraparound shield head is one of the promising candidates for narrow track recording because of its high cross-track head filed gradient
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  • Measurement of the read/write characteristics of perpendicular magnetic recording media with a static-tester
    Ryosuke TATSUNO, Kenji MIURA, Hajime AOI, Hiroaki MURAOKA
    Article type: Article
    Session ID: MMS2009-42
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_39
    CONFERENCE PROCEEDINGS FREE ACCESS
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    As a future perpendicular magnetic recording technology, a discrete track medium recording and a patterned medium recording are widely studied. Now, they are still at trial manufacture stages, including the media patterning process. Manufacturing and evaluating of a disk with circularly patterned tracks is still not easy. Evaluation system requires high-accuracy positioning of a small sample that is not disk shape. Therefore we tried to develop a static-tester that can evaluate the read-write characteristics of a sample with small discrete track area. We report the constitution of a static-tester and the measurement result of the perpendicular magnetic recording media.
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  • Estimation of Track Density of Shingled Writing for Two-Dimensional Magnetic Recording
    Kenji MIURA, Eiji YAMAMOTO, Hajime AOI, Hiroaki MURAOKA
    Article type: Article
    Session ID: MMS2009-43
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_45
    CONFERENCE PROCEEDINGS FREE ACCESS
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    In this paper, the feasibility of two-dimensional magnetic recording is discussed from the viewpoint of high track density. 747 curves of shingled track were measured using existing heads and media and were interpreted with a squeezing model dominated by the SN ratio of the read head output. As long as a reader can be placed on the median line of the squeezed data area, wider OTC than that of conventional writing will result. The modeled 747 curves were in good agreement with the experimental data for both conventional writing and shingled writing. The feasibility of narrow track pitch shingled writing was shown, however, write-to-write misregistration should be minimized to maximize the track density.
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  • 3-D FD-TD analysis of an optical near-field generated by a metallic thin-film for thermally assisted magnetic recording
    Tatsuya KAISE, Kazunori HIRASAWA, Yasushi KANAI, Yutaka TANGE, Tadao O ...
    Article type: Article
    Session ID: MMS2009-44
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_51
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Thermally assisted magnetic recording is one of the possible candidates that achieves the areal densities of 1 terabit/inch^2. In the scheme, the recording layer is heated by the external, optical energy. The signal is recorded when the coercive force of recording layer is reduced, therefore, relatively small magnetic field is necessary to switch the medium. In this report, the optical near fields from the metallic, thin film have been obtained for various structures with and without the aperture by using the three-dimensional finite-difference time-domain (FD-TD) method. Finally, the head field and the near field energy distributions are compared and discussed if a proper thermal energy can be applied to the recording layer.
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  • Performance evaluation of LDPC code in BPM read/write channel with write-error
    Yasuaki NAKAMURA, Yoshihiro OKAMOTO, Hisashi OSAWA, Hajime AOI, Hiroak ...
    Article type: Article
    Session ID: MMS2009-45
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_59
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Low-density parity check (LDPC) coding and iterative decoding system is studied in a magnetic recording system using bit-patterned media (BPM) with recording error. In order to correctly write the recording sequence on the intended islands in the recording channel using BPM, the write synchronization to synchronize the write sequence with the position of island is required. We propose the LDPC coding and iterative decoding system which controls the reliability information by the results of error detection using the parity check matrix of LDPC code is to curb the influence of write-error due to loss of synchronization on the iterative decoding process. The performance is evaluated in the R/W channel using BPM at 2Tbit/inch^2 with write error by computer simulation. The results show that the proposed system provides the better performance compared with a conventional system without controlling the reliability information.
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  • Analysis of hologram recording characteristics by using Beam Propagation Method
    Shuhei YOSHIDA, Akiyo GOTO, Manabu YAMAMOTO
    Article type: Article
    Session ID: MMS2009-46
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_65
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Photopolymers are suitable for recording thick phase holograms. In addition, photopolymers are stable media with high diffraction efficiency; therefore, they are widely used as holographic recording media. A photopolymer must satisfy certain criteria to qualify as a practical recording medium. However, the reaction processes of such photopolymers are highly complicated. In this study, we have simulated the formation of diffraction gratings in photopolymers using the diffusion model based on elementary reactions, and analyzed their diffraction characteristics in detail by the beam propagation method. Moreover, we also performed experimental interference fringe recording and evaluated the recording characteristics of photopolymer media. In addition, we propose a simulation method for the signal evaluation. This simulation method can replicate three dimensional writing/readout processes of hologram. We consider that the results of our analysis will provide useful information for the development of holographic data storage.
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  • [title in Japanese]
    Article type: Appendix
    Pages App1-
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_App1
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • [title in Japanese]
    Article type: Appendix
    Pages App2-
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_App2
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • [title in Japanese]
    Article type: Appendix
    Pages App3-
    Published: June 11, 2009
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.33.22.0_App3
    CONFERENCE PROCEEDINGS FREE ACCESS
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