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ABSTRACT: This paper presents a virtual reality (VR)-enhanced new hand rehabilitation support system that enables patients to exercise alone. This system features a multi-degrees-of-freedom (DOF) motion assistance robot, a VR interface for patients, and a symmetrical master-slave motion assistance training strategy called "self-motion control," in which the stroke patient's healthy hand on the master side creates the assistance motion for the impaired hand on the slave side. To assist in performing the fine exercise motions needed for functional recovery of the impaired hand, the robot was constructed in an exoskeleton with 18 DOFs, to assist finger and thumb independent motions such as flexion/extension and abduction/adduction, thumb opposability, and hand-wrist co- ordinated motions. To enhance the effectiveness of the exercises, audio-visual instructions of each training motion using VR technology were designed with the input of clinician researchers. Experimental results from healthy subjects and patients show sufficient performance in the range of motion of the robot as well as sufficient assistance forces.
IEEE/ASME Transactions on Mechatronics 03/2012; · 2.87 Impact Factor
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Physical Review B 07/2011; 84(3):035309. · 3.69 Impact Factor
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ABSTRACT: Mechanical butt joint of a high-temperature superconducting (HTS) cable with a metal jacket has been investigated for a remountable HTS magnet where parts can be mounted and demounted iteratively to allow a superconducting magnet for a fusion reactor to be assembled and repaired. In this study, an optimum structure to achieve relatively uniform contact pressure distribution on joint surface in the mechanical butt joint was suggested by structural analysis. Then, joint resistance in mechanical butt joint of a stacked BSCCO 2223 cable with copper jacket was evaluated experimentally using an experimental setup established based on the structural analysis, to confirm effect of decreasing joint resistance by the joint structure. The results showed that the structure can reduce joint resistance to 140 nΩ for the BSCCO 2223 cable having 1 kA of critical current at liquid nitrogen temperature.
IEEE Transactions on Appiled Superconductivity 07/2011; · 1.04 Impact Factor
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ABSTRACT: The flux pinning behaviors for the heavy ion irradiated Er123 films are investigated based on the detailed J<sub>c</sub>(B,T,θ) properties. The double peaks of F<sub>p</sub> curves for B//c appear in case of the matching field of 0.3 T along c-axis and 1.7 T tilted from c-axis. In addition, the peaks on J<sub>c</sub>(θ) at θ = 0°(B//c), which originate from the columnar defects, decrease with increasing magnetic field but increase again near the irreversibility field. We found that the cooperation model of the c-axis correlated and random pinning centers can describe the observed double peak behavior of F<sub>p</sub>(B) and the angular dependence of J<sub>c</sub> related to the correlated pinning.
IEEE Transactions on Appiled Superconductivity 07/2011; · 1.04 Impact Factor
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Physical Review B 06/2011; 83(23):235305. · 3.69 Impact Factor
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ABSTRACT: A multi-step word-line control technology (MWC), combined with a new hierarchical cell SRAM architecture (HCA), has been developed to overcome rapid increase in random variability with no area penalty. A 40-nm-node 0.248-μm<sup>2</sup>-cell SRAM using a single power supply has been successfully fabricated, pushing up bit density to 2.98 Mb/mm<sup>2</sup>. MWC improved VDD_min@-6σ by 0.34 V and 0.22 V for read and write operations, respectively, enabling stable 1.0 V operations. Four nanosecond SRAM access time is achieved by adopting HCA, which cancels out a 1.4 ns increase of access delay caused by MWC.
IEEE Journal of Solid-State Circuits 05/2011; · 3.23 Impact Factor
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K. Okada,
K. Matsushita,
K. Bunsen,
R. Murakami,
A. Musa,
T. Sato,
H. Asada,
N. Takayama,
Ning Li, S. Ito,
W. Chaivipas,
R. Minami,
A. Matsuzawa
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ABSTRACT: This paper presents a 60GHz direct-conversion transceiver using 60GHz quadrature oscillators. The 65nm CMOS transceiver realizes the IEEE802.15.3c full-rate wireless communication for every 16QAM/8PSK/QPSK/BPSK mode. The maximum data rates with an antenna built in the package are 8Gb/s in QPSK mode and 11 Gb/s in 16QAM mode within a BER of <;1CH, and the transmitter and the receiver consume 186mW and 106mW, respectively.
Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2011 IEEE International; 03/2011
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ABSTRACT: This paper describes an algorithm for generating test signals to efficiently test the linearity of ADCs. Linearity is an important testing item for ADCs, and it takes a long time (hence is costly) to test low-sampling-rate, high-resolution ADCs. We here propose to generate a test signal consisting of multiple sine waves, to precisely test the linearity for specific important codes (such as around the center of the output codes), using an arbitrary waveform generator (AWG) and an analog filter. We have performed MATLAB simulation to validate our algorithm, and the results show that in some cases the testing time can be reduced to half that for conventional sine wave histogram testing.
Circuits and Systems (APCCAS), 2010 IEEE Asia Pacific Conference on; 01/2011
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ABSTRACT: This paper describes a background calibration algorithm for a pipelined ADC with an open-loop amplifier using a Split ADC structure. The open-loop amplifier is employed as a residue amplifier in the first stage of the pipelined ADC to realize low power and high speed. However it suffers from nonlinearity, and hence needs calibration; conventional background calibration methods take a long time to converge. We investigated the split ADC structure for background calibration of the residue amplifier nonlinearity and gain error as well as the DAC nonlinearity all together with fast convergence, and validated its effectiveness by MATLAB simulation.
Circuits and Systems (APCCAS), 2010 IEEE Asia Pacific Conference on; 01/2011
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ABSTRACT: This paper describes a time-to-digital converter (TDC) architecture with fine time resolution, self-calibration and self-testing, and these features are realized by the following: (1) Encoder circuit that ensures monotonic characteristics. (2) Self-calibration circuit for linearity improvement. (3) Stochastic architecture for fine time resolution. (4) Self-testing for reliability requirements. These features can be implemented with an advanced fine CMOS process using digital design methodology. The circuit structure and operation are described, and MATLAB simulation results are presented.
Circuits and Systems (APCCAS), 2010 IEEE Asia Pacific Conference on; 01/2011
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ABSTRACT: To shed light on the correlation between the Hall coefficient (R<sub>H</sub>) and electrical resistivity (ρ) , we performed simultaneous measurements of these two transport coefficients in fcc dihydride phase of yttrium ( YH <sub>x</sub>) , having H/Y values ranging from 1.73 to 2.04. Unlike the typical behavior of metals, an approximately linear relationship was observed between R<sub>H</sub> and ρ at room temperature after dihydrogenation of yttrium. Interpretation of this relationship, based on the Boltzmann–Bloch scheme, reveals that the transverse (cyclotron) relaxation rate (1/τ<sub>c</sub>) of the carriers is relatively insensitive to the generation of hydrogen defects in the dihydride phase of yttrium, unlike the longitudinal relaxation rate (1/τ) , which is affected by the presence of hydrogen defect. Low-temperature (77 K) measurements of R<sub>H</sub> and ρ on the same samples show that the approximately linear relationship observed at room temperature disappears but a certain nonlinear relationship may exist at 77 K.
Journal of Applied Physics 11/2010; · 2.17 Impact Factor
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T. Shimozuma,
S. Kubo,
Y. Yoshimura,
H. Igami,
H. Takahashi,
S. Kobayashi, S. Ito,
Y. Mizuno,
K. Okada,
Y. Takita,
T. Mutoh,
H. Idei,
R. Minami,
T. Kariya,
T. Imai
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ABSTRACT: In LHD, an ECH system for fusion-relevant plasma heating has been greatly progressed with the development of megawatt gyrotrons. Net power of 3.7 MW could be injected into LHD. For stable operation, a new position and profile monitor of the mmw-beams in evacuated transmission lines is developed.
Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2010 35th International Conference on; 10/2010
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ABSTRACT: This paper introduces a method for discussing the association between human personality based on egogram scores and the results of classifying the electroencephalogram (EEG) patterns while listening to the music. The egogram based on psychological testing is used for analyzing his/her personality. The frequencies of the EEG analyzed are the components that contain significant and immaterial information and have different importance. We express the different importance through the weight value on frequencies using real-coded genetic algorithm. Then, the EEG patterns, which are determined based on the evaluation of the impression on the music, are classified using the k-nearest neighbor method. Finally, we discuss the association between his/her personality and the individual characteristic in the EEG analysis. An interesting tendency was that the false-detection accuracy of the EEG pattern, meaning the response on negative stimuli, did not become low when the score and level on ego states of Adult was extreme.
Natural Computation (ICNC), 2010 Sixth International Conference on; 09/2010
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ABSTRACT: It is an important issue that the relationship between personality and individual characteristic of an electroencephalogram (EEG) for using a personalized brain computer interface on daily basis. In this paper, we introduce a method for discussing the relationship between personality based on egogram scores and the results of the EEG pattern detection. The egogram based on psychological testing is used for analyzing human personality. The frequencies of the EEG analyzed are the components that contain significant and immaterial information and have different importance. We express the different importance through the weight value on frequencies using real-coded genetic algorithm. Then, the EEG patterns, which are determined based on the evaluation of the impression on the music, are classified/detected using the knearest neighbor method. Finally, we discuss the relationship between human personality and the individual characteristic in the EEG analysis. An interesting tendency was that the false-detection ratio of the EEG pattern, meaning the response on negative stimuli, did not become low when the score and level on ego states of Adult was extreme.
Computational Technologies in Electrical and Electronics Engineering (SIBIRCON), 2010 IEEE Region 8 International Conference on; 08/2010
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ABSTRACT: A remountable high-temperature superconducting (HTS) magnet where parts can be mounted and demounted is proposed to allow a superconducting magnet for a fusion reactor to be assembled and repaired. A conceptual study of a mechanical butt joint for a stacked HTS cable with metal jacket was carried out. In this study, contact pressure distribution at the joint surface was evaluated by structural analysis to investigate the deformation of the joint region due to the joint force and the influence of the thermal strain on joint performance. Analytical results showed that thermal strain and Young's modulus of the constituent material strongly affect the contact pressure distribution. In addition, combinations of parallel and perpendicular joint forces, and the procedure with which they are applied, have a strong impact on the realization of a remountable joint in a HTS cable.
IEEE Transactions on Appiled Superconductivity 07/2010; · 1.04 Impact Factor
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ABSTRACT: A concept of remountable HTS magnet has been proposed to simplify fabrication of a superconducting magnet for a fusion reactor and to reduce maintenance cost of the reactor. For realization of the remountable HTS magnet system, mechanical butt joint of a stacked BSCCO 2223 cable has been investigated experimentally with large joint stress. In this study, 10 layered BSCCO 2223 cable with copper jacket is used as a test cable, and the roughness of joint surface is controlled quantitatively by using several different particle sizes of abrasive particles. Then the relation between the joint stress and resistance is evaluated through the mechanical butt joint test of the cable under several experimental conditions. Although dependence of the joint resistance on the joint stress is observed the relationship between roughness and joint resistance is not observed clearly due to not coincidence in surface flatness of the test cables.
IEEE Transactions on Appiled Superconductivity 07/2010; · 1.04 Impact Factor
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ABSTRACT: The diffusion behavior of hydrogen contained in the surface layer of oxynitrides serving as models for poly-Si/oxynitride interfaces in MOS transistors was studied with H depth profiling by nuclear reaction analysis. The poly-Si/oxynitride interface is found to contain mobile and stable H species. The mobile H species tends to desorb in vacuum at room temperature. A TDDB improvement caused by resting in air for more than 24 h prior to the post nitridation annealing is attributed to the reduction of mobile H species. Eliminating the mobile H from the gate interface is thus suggested to improve the reliability of oxynitride dielectrics.
Reliability Physics Symposium (IRPS), 2010 IEEE International; 06/2010
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ABSTRACT: Random arrangements of ferromagnetic MnAs nanoclusters were deposited on (111)B-GaInAs surfaces by standard metal-organic vapor-phase epitaxy (MOVPE). Ordered arrangements of MnAs nanoclusters and cluster chains were obtained by selective-area MOVPE on prepatterned (111)B-GaAs substrates. This new method enables one to control the arrangement of nanoclusters in the growth process offering interesting opportunities to tune the properties of individual MnAs clusters as well as the interaction between the carriers in the surrounding semiconductor matrix and the clusters. The magnetic anisotropy of the MnAs clusters was investigated by magnetic force microscopy and ferromagnetic resonance measurements. The in-plane magnetic anisotropy is mainly determined by the interplay of cluster shape and magnetocrystalline anisotropy while the hard magnetic axis of the clusters is perpendicular to the sample plane independent of cluster shape. The magnetotransport measurements demonstrate that the cluster arrangements strongly influence the transport properties.
Journal of Applied Physics 02/2010; · 2.17 Impact Factor
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ABSTRACT: Practical characterization of active and passive devices in CMOS technology is presented in this paper for designing millimeter-wave power amplifiers. Detailed modeling strategy for transmission line, T-junction, and transistor is explained with some actually-designed millimeter-wave amplifiers. A 4-stage PA is implemented in 65 nm CMOS process. A 20 dB power gain and a 9.9 dBm 1 dB output compression point are achieved at 60 GHz.
Radio-Frequency Integration Technology, 2009. RFIT 2009. IEEE International Symposium on; 01/2010
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ABSTRACT: This paper proposes a de-embedding method for on-chip S-parameter measurements at mm-wave frequency. The proposed method uses only two transmission lines with different length. In the proposed method, a parasitic-component model extracted from two transmission lines can be used for de-embedding for other-type DUTs like transistor, capacitor, inductor, etc. The experimental results show that the error in characteristic impedance between the different-length transmission lines is less than 1¿.
Microwave Conference, 2009. APMC 2009. Asia Pacific; 01/2010
