Yoshiharu Yonezawa

Hiroshima Institute of Technology, Hirosima, Hiroshima, Japan

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Publications (102)32.43 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: We report on an activity monitoring system for elderly persons living alone. Caregivers would like to know whether the person is talking during their daily activity. Our monitoring system consists of a recorder and a personal computer. The recorder, attached to the subject's chest, employs two microphones, a tri-axis accelerometer, two low-power amplifiers, a low-power microcomputer (MC) and a 2GB micro SD Memory Card (SDMC). One of the microphones is set in the direction of the chest for recording the person's voice, and the other microphone is set to the opposite side for recording surrounding sound. The microphone outputs and the accelerometer outputs are sent to the MC’s 10 bit analog to digital converters and sampled at 4000Hz and 50Hz, respectively. The MC detects the length of the conversation time from the microphone outputs, and the posture and behavior are detected from the accelerometer outputs every 5 seconds. The detected time, posture and behavior are stored in the SDMC. The data can be downloaded from the memory card and sent to appropriate stations. The system is used to monitor the health and physical conditions during daily life of elderly persons living alone.
    No preview · Article · Apr 2015 · Biomedical sciences instrumentation
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    ABSTRACT: We have developed an ultrasonic stride length measuring system for analyzing the human gait. All elements of the system are quite small and each fit into an appropriate package. An ultrasonic transmitter, a digital compass, a radio transmitter and a microcontroller are attached to the subject’s heel on the right shoe and in the direction of the left shoe. Two ultrasonic receivers, a digital compass, a radio receiver, a microcontroller and a 1GB SD memory card are installed on the left shoe. The ultrasonic receivers are attached to the toe and heel in the direction of the right shoe. The walking direction is thus detected by the compass attached on the right and left shoes, respectively. The stride length is detected by the difference between the radio wave and ultrasonic propagation velocities. The stride length is corrected by the detected walking direction, and then the corrected stride length is stored in the SD memory card. When downloaded, the memory card gives the accurate stride length which then is used to characterize the subject’s gait during daily activity.
    No preview · Article · Nov 2014 · Biomedical sciences instrumentation
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    ABSTRACT: During treatment of positive pressure ventilator, an intubation tube is inserted into the patient’s trachea. If the intubation tube is pulled out during the treatment, the patient condition may become critical. We reported on a system which enables an alarm before the tube might be pulled out by the patient’s hand. A detection electrode in the developed system is attached to the intubation tube and we proceeded to experiment with the system. Twelve healthy volunteers participated in the experiment, and were requested to place their hand at a distance of 10 cm, 5 cm, 2.5 cm, and 0 cm (contact), respectively, from the intubation tube. The preliminary result of this experiment showed that the oscillation frequency of the developed sensor changes accordingly to the distance between the electrode and the subject’s hand. By using the result, the threshold values for the alarm could be determined. In a practicability evaluation experiment, the system made alarms successfully; an attention lamp (yellow) was lit when the subject’s hand is in less than 5 cm from the intubation tube, and a warning lamp (red) was lit when the subject’s hand is contacted with the tube.
    No preview · Article · Jan 2014
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    ABSTRACT: We have developed a drip infusion solution monitoring system for hospital and care facility use that is much more accurate than our previous reported system. The system consists of two electrodes and an acceleration sensor. The electrodes, which are wrapped around the infusion supply polyvinyl chloride (PVC) tube from the solution bag and the drip chamber, measure the growth and fall of each drop of infusion solution. The drip rate is detected from the fall of each drop. In addition, the acceleration sensor is attached to the outside of the drip chamber and detects the tilt angle of that chamber. The injected infusion solution amount is calculated by the infusion solution quantity per one drop and the drip rate. However, the quantity changes depend on the tilt angle of the drip chamber. The quantity of each drop is then corrected by the tilt angle of the drip chamber.
    No preview · Article · Apr 2013 · Biomedical sciences instrumentation
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    ABSTRACT: Amyotrophic lateral sclerosis is a progressive degeneration of motor neurons. Patients with the disease lose their ability to speak and to use their hands as the disease progresses. We have developed a new electronic communication system that enables communication by blinking of the eyes. The system consists of a light emitting diode (LED), two silicone rubber electrodes, an electrooculogram (EOG) recorder, a microcontroller, a sound reproduction board, a pillow speaker and a low power mobile phone. The two silicone rubber electrodes record the EOG induced by blinking the eyes synchronized with LED flashing. The EOG is amplified by the EOG recorder. The microcontroller detects the blinking from the amplified EOG, and then their meanings are confirmed by voice. After that, the patient’s intention is transmitted to the nurse by a low power mobile phone so the care giver is kept in the loop.
    No preview · Article · Apr 2013 · Biomedical sciences instrumentation
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    ABSTRACT: We have developed an ultra-flexible skin electrode to monitor a patient’s electrocardiogram (ECG) during daily activity. This electrode consists of a 1.5 micrometer thick polyester film printed with electro-conductive paint. The electrode is attached to the outside of a polyethylene bag filled with a high viscoelastic fluid. When the electrode is placed securely on the skin, it correspondingly changes its shape, and electrode movement artifact is thereby decreased. The electrode improves long-term recording of the ECG by maintaining capacitance-coupled impedance between the electrode and the skin.
    No preview · Article · Apr 2013 · Biomedical sciences instrumentation
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    ABSTRACT: Objective-To compare data obtained with an inertial sensor system with results of subjective lameness examinations performed by 3 experienced equine veterinarians for evaluation of lameness in horses. Animals-106 horses. Procedures-Horses were evaluated for lameness with a body-mounted inertial sensor system during trotting in a straight line and via subjective evaluation by 3 experienced equine practitioners who performed complete lameness examinations including lunging in a circle and limb flexion tests. Agreement among evaluators regarding results of subjective evaluations and correlations and agreements between various inertial sensor measures and results of subjective lameness evaluations were determined via calculation of Fleiss' κ statistic, regression analysis, and calculation of 95% prediction intervals. Results-Evaluators agreed on classification of horses into 3 mutually exclusive lameness categories (right limb lameness severity greater than left limb lameness severity, left limb lameness severity greater than right limb lameness severity, or equal right and left limb lameness severity) for 58.8% (κ = 0.37) and 54.7% (κ = 0.31) of horses for forelimb and hind limb lameness, respectively. All inertial sensor measures for forelimb and hind limb lameness were positively and significantly correlated with results of subjective evaluations. Agreement between inertial sensors measures and results of subjective evaluations was fair to moderate for forelimb lameness and slight to fair for hind limb lameness. Conclusions and Clinical Relevance-Results of lameness evaluation of horses with an inertial sensor system and via subjective lameness examinations were significantly correlated but did not have strong agreement. Inertial sensor-based evaluation may augment but not replace subjective lameness examination of horses.
    No preview · Article · Jan 2013 · American Journal of Veterinary Research
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    ABSTRACT: We have developed a remote drip infusion monitoring system for use in hospitals. The system consists of several infusion monitoring devices and a central monitor. The infusion monitoring device employing a Bluetooth module can detect the drip infusion rate and an empty infusion solution bag, and then these data are sent to the central monitor placed at the nurses' station via the Bluetooth. The central monitor receives the data from several infusion monitoring devices and then displays graphically them. Therefore, the developed system can monitor intensively the drip infusion situation of the several patients at the nurses' station.
    No preview · Article · Aug 2012 · Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference
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    ABSTRACT: We have developed a drip infusion warning system for hospital and care facility use. In general, two kinds of infusion sets are used, which have drop factors of either 20 or 60. (A drop factor is the number of drops to deliver 1 ml of infusion solution.) When an infusion set having a 20 drop factor is used, the number of drops per drip is adjusted to 20. If an infusion set has a drop factor of 60, then the infusion volume rate becomes three times as much. This may result in legal consequences if the patient is injured. In this study, a drip infusion warning system detects whether the infusion is a 20 or a 60 drop factor. The system consists of two electrodes, one wrapped around the infusion supply polyvinyl-chloride tube, and another one around the drip chamber. The electrical impedance between two electrodes is changed by the growth and fall of each drop of fluid. The drop growth length especially changes, depending on the type of infusion set used. Therefore, the two types of infusion sets can be identified by monitoring the drop length. Our warning system detects whether the infusion set used corresponds to a 20 or 60 drop factor, so the system can reduce human errors.
    No preview · Article · Jul 2012 · Biomedical sciences instrumentation
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    ABSTRACT: We have developed a new ultrasonic stride length measuring system for analyzing the human gait. An ultrasonic transmitter, a radio transmitter, a pressure sensor and microcontroller are attached to the subject’s heel on the right shoe and in the direction of the left shoe. Two ultrasonic receivers, a radio receiver, a microcontroller and a 1GB SD memory card are installed on the left shoe. Ultrasonic receivers are attached to the toe and heel, in the direction of the right shoe. When the right foot contacts the ground, its heel-mounted ultrasonic and radio transmitters simultaneously transmit to the left shoe. However, radio propagation velocity is far faster than ultrasonic velocity. Therefore, the radio wave acts as a start signal to the radio receiver of the left shoe, indicating the start of ultrasound transmission from the right shoe. Upon receiving the start signal, the microcontroller timer starts to measure each ultrasound propagation time from the right shoe to the left shoe. Distance between right and left shoes is calculated with the time and ultrasound velocity and stored in the SD memory card. Stride length is calculated with a cosine function, by using the obtained distances and the distance between the toe and heel of the left shoe, by a conventional computer. The stride length can then be used for many characterizations of the subject’s gait.
    No preview · Article · Jul 2012 · Biomedical sciences instrumentation
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    ABSTRACT: To assess the analytic sensitivity of an inertial sensor system for detection of the more severely affected forelimb in horses with bilateral lameness. 18 adult horses with forelimb lameness. Horses were fitted with inertial sensors and evaluated for lameness with a stationary force plate as they were trotted in a straight line. Inertial sensor-derived measurements for vertical head movement asymmetry (HMA) and vector sum (VS) of maximum and minimum head height differences between right and left halves of the stride were used to predict differences in mean peak vertical force (PVF) as a percentage of body weight between the right and left forelimbs. Repeatability was compared by calculation of the intraclass correlation coefficient (ICC) for each variable. Correct classification percentages for the lamer forelimb were determined by use of a stationary force plate as the standard. SEs of the prediction of difference in PVF between the right and left forelimbs from HMA and VS were 6.1% and 5.2%, respectively. Head movement asymmetry (ICC, 0.72) was less repeatable than PVF (ICC, 0.86) and VS (ICC, 0.84). Associations were positive and significant between HMA (R(2) = 0.73) and VS (R(2) = 0.81) and the difference in PVF between the right and left forelimbs. Correct classification percentages for HMA and VS for detecting the lamer forelimb were 83.3% and 77.8%, respectively. Results suggested that an inertial sensor system to measure vertical asymmetry (HMA and VS) due to forelimb lameness in horses trotting in a straight line has adequate analytic sensitivity for clinical use. Additional studies are required to assess specificity of the system.
    No preview · Article · Mar 2012 · American Journal of Veterinary Research
  • Shingo Matsuoka · Hidekuni Ogawa · Hiromichi Maki · Yoshiharu Yonezawa

    No preview · Article · Jan 2012
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    ABSTRACT: To determine repeatability of a wireless, inertial sensor-based lameness evaluation system in horses. 236 horses. Horses were from 2 to 29 years of age and of various breeds and lameness disposition. All horses were instrumented with a wireless, inertial sensor-based motion analysis system on the head (accelerometer), pelvis (midline croup region [accelerometer]), and right forelimb (gyroscope) before evaluation in 2 consecutive trials, approximately 5 minutes apart, as the horse was trotted in a straight line. Signal-processing algorithms generated overall trial asymmetry measures for vertical head and pelvic movement and stride-by-stride differences in head and pelvic maximum and minimum positions between right and left sides of each stride. Repeatability was determined, and trial difference was determined for groups of horses with various numbers of strides for which data were collected per trial. Inertial sensor-based measures of torso movement asymmetry were repeatable. Repeatability for measures of torso asymmetry for determination of hind limb lameness was slightly greater than that for forelimb lameness. Collecting large numbers of strides degraded stride-to-stride repeatability but did not degrade intertrial repeatability. The inertial sensor system used to measure asymmetry of head and pelvic movement as an aid in the detection and evaluation of lameness in horses trotting in a straight line was sufficiently repeatable to investigate for clinical use.
    No preview · Article · Sep 2011 · American Journal of Veterinary Research
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    ABSTRACT: We have developed a new mobile phone-based safety support system for transmitting information of a wandering elderly person's location and the environmental sounds around that person. The system consists of a wearable sensor and a conventional desktop PC with Internet access acting as the server computer. The wearable sensor, which is attached behind the neck of the elderly person's shirt, is composed of a low transmitting power mobile phone (W-SIM), a small microphone and a one chip microcontroller. The wandering elderly person's location is identified within 100 m from the mobile phone company's antenna ID via the W-SIM. The caregiver sets the elderly person's movement area by specialized computer software. When the elderly person goes out of the area, the sensor automatically records the environmental sound around the wandering elderly person for the presumption of the person's situation with the small microphone. The W-SIM sends both the wandering elderly person's location and the environmental sound to the server computer. The server computer informs automatically the caregiver by the e-mail. The caregiver can monitor the sound and the map of the wandering person's location via Internet. The sound enables the presumption of an accurate location and the situation of the wandering elderly person.
    No preview · Article · Aug 2011 · Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference
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    ABSTRACT: A daily living activity remote monitoring system has been developed for supporting solitary elderly people. The monitoring system consists of a tri-axis accelerometer, six low-power active filters, a low-power 8-bit microcontroller (MC), a 1GB SD memory card (SDMC) and a 2.4 GHz low transmitting power mobile phone (PHS). The tri-axis accelerometer attached to the subject's chest can simultaneously measure dynamic and static acceleration forces produced by heart sound, respiration, posture and behavior. The heart rate, respiration rate, activity, posture and behavior are detected from the dynamic and static acceleration forces. These data are stored in the SD. The MC sends the data to the server computer every hour. The server computer stores the data and makes a graphic chart from the data. When the caregiver calls from his/her mobile phone to the server computer, the server computer sends the graphical chart via the PHS. The caregiver's mobile phone displays the chart to the monitor graphically.
    No preview · Article · Aug 2011 · Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference
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    ABSTRACT: A non-constraint cardiac vibration, respiration, and body movement monitoring system has been developed. The sensor system is designed to be easily installable under an existing bed mattress. The sensor consists of a 40-kHz ultrasound transmitter and receiver pair. The transmitted ultrasound is reflected on the mattress' undersurface, and the amplitude of the received ultrasonic wave is modulated by the shape of the mattress, and parameters such as respiration, cardiac vibration, and movement. The physiological parameters can be extracted from the reflected ultrasound by an envelope detection circuit. To confirm the accuracy of the developed system, measurements were performed on 6 normal male subjects aged 25.0 ± 6.7 years, using 2 pocket spring coil mattresses and a polyurethane foam mattress. The results revealed that the physiological parameters were monitored with an 84.2% average accuracy for all mattresses when the subjects lay on the beds in the supine, lateral, and prone positions.
    No preview · Article · Aug 2011 · Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference
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    ABSTRACT: Zero-field muon spin relaxation experiments have been carried out in the Pr(Os1-xRux)4Sb12 and Pr1-yLayOs4Sb12 alloy systems to investigate broken time-reversal symmetry (TRS) in the superconducting state, signaled by the onset of a spontaneous static local magnetic field Bs. In both alloy series Bs initially decreases linearly with solute concentration. Ru doping is considerably more efficient than La doping, with a ~50% faster initial decrease. The data suggest that broken TRS is suppressed for Ru concentration x≳0.6 but persists for essentially all La concentrations. Our data support a crystal-field excitonic Cooper pairing mechanism for TRS-breaking superconductivity.
    No preview · Article · Mar 2011 · Physical review. B, Condensed matter
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    ABSTRACT: Zero-field muon spin relaxation (muSR) experiments have been carried out in the Pr(Os1-xRux)4Sb12 and Pr1-yLayOs4Sb12 alloy systems to investigate broken time-reversal symmetry (TRS) in the superconducting state, signaled by the onset of a spontaneous static local magnetic field Bs. In both alloy series Bs initially decreases linearly with solute concentration. Ru doping is considerably more efficient than La doping ,with a ˜50% faster initial decrease. The data suggest that broken TRS is suppressed for Ru concentration larger than 0.6, but persists for essentially all La concentrations. Our data support the theory of TRS-breaking superconductivity via crystal-field excitonic Cooper pairing of Koga, Matsumoto, and Shiba.
    No preview · Article · Mar 2011
  • Source
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    ABSTRACT: Zero-field muon spin relaxation experiments have been carried out in the Pr(Os_{1-x}Ru_x)_4Sb_12 and Pr_{1-y}La_yOs_4Sb_12 alloy systems to investigate broken time-reversal symmetry (TRS) in the superconducting state, signaled by the onset of a spontaneous static local magnetic field B_s. In both alloy series B_s initially decreases linearly with solute concentration. Ru doping is considerably more efficient than La doping, with a ~50% faster initial decrease. The data suggest that broken TRS is suppressed for Ru concentration x >~ 0.6, but persists for essentially all La concentrations. Our data support a crystal-field excitonic Cooper pairing mechanism for TRS-breaking superconductivity.
    Full-text · Article · Feb 2011
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    ABSTRACT: We have developed a telemedicine system to monitor a patient’s electrocardiogram (ECG) and heart sounds (PCG) during daily activity. The complete system, consisting of an ECG recorder, an accelerometer and a 2.4 GHz low power mobile phone, is mounted on three chest sensing electrodes. The accelerometer records the PCG produced by closing of the mitral and aortic valves (S1 and S2). The sampled ECG and PCG are stored in the system for two minutes and continuously updated. When a patient feels heart discomfort such as angina or an arrhythmia, he/she pushes the data transmission switch on the system. The ECG and PCG for the next two minutes are stored in the system, and then the system then sends the four minutes of stored data directly to a hospital server computer via the 1.9 GHz low power mobile phone. These data are stored on the server and then downloaded to the physician’s Java configured mobile phone. The physician can then check the patient’s cardiac condition, regardless of patient or physician locations, and then take appropriate actions.
    No preview · Article · Jan 2011 · Biomedical sciences instrumentation

Publication Stats

432 Citations
32.43 Total Impact Points

Institutions

  • 1976-2013
    • Hiroshima Institute of Technology
      • • Department of Health Science
      • • Department of Electronics
      • • Department of Electrical Engineering
      Hirosima, Hiroshima, Japan
  • 1989-2012
    • University of Missouri
      • Department of Veterinary Medicine and Surgery
      Columbia, Missouri, United States
  • 2007-2011
    • Tokyo Metropolitan University
      • Department of Physics
      Tokyo, Tokyo-to, Japan