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RISS 인기검색어
- 검색키워드
- 저자 : Makikawa, Keisuke (검색결과 4 건)
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Shima Okada,Masaaki Makikawa,Yuko Ohno,Kumi Kato-Nishimura,Ikuko Mohri,Masako Taniike 대한의용생체공학회 2011 Biomedical Engineering Letters (BMEL) Vol.1 No.4
Purpose Obtaining an adequate amount of sleep is a necessity for normal childhood development. Gross body movements (GMs) during sleep in normal children vary by sleep stage and developmental state, and abnormalities in GMs characterize specific developmental pathophysiologies. Therefore, GM monitoring in children is of great importance when tracking normal development. While videosomnography is a widely used technique for monitoring GMs, it is qualitative, and a quantitative method for assessing GMs is required. We developed a novel, simple noncontact method based on video analysis for the detection of GMs during sleep. Methods Our method used image difference processing of videos to detect GMs. We conducted a preliminary evaluation of our technique by assessing the relationships between sleep stages determined by polysomnography and GMs assessed by the video images of 14 young children (3-7 years old). Results Our experiments suggest that this method may be used to detect GMs during sleep in children. The rates of GMs during sleep in children significantly differed among wake,light sleep, and slow wave sleep stages. However, rapid eye movement sleep was difficult to distinguish, probably due to age-related changes in neurological development. Conclusions Our novel method could detect GMs during sleep by difference processing of video images, and we demonstrated the possible utility of this technique for assessing sleep in children. Our proposed technique requires further evaluation, but we suggest that GM detection via video images may be more useful than the presently available qualitative methods.
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Yusuke Sakaue,Masaaki Makikawa 대한의용생체공학회 2015 Biomedical Engineering Letters (BMEL) Vol.5 No.4
Purpose Multiple surface electrodes must be attached to theskin for high-accuracy signal source position estimationinside the human body, and can be uncomfortable for thesubject. This paper presents a method for signal sourceposition estimation inside the human body to solve thisproblem. In our method, the human body is modeled as anelectrical circuit, consisting of an internal resistance and apotential source, which can both be measured simultaneouslyvia two surface electrodes using switching voltage dividertechnology. The purpose of this study is to reduce thenumber of electrodes required for human body signal sourcelocalization, and the estimation ability of the proposedmethod is confirmed here. Methods A single signal source consisting of positive andnegative poles was set inside a water tank filled with tapwater to simulate a human body, and a sine wave was generatedusing this signal source. Stainless steel measurement electrodeswere used to obtain the signal source potential and internalresistance. Equations representing the signal source positionwere developed using the information at each electrode, andsignal source position was estimated by solving simultaneousequations. Results Signal source position was estimated correctly withmaximum localization error of 2.6 mm. Conclusion Our method showed that the signal sourceposition inside a water tank filled with tap water can beestimated using internal resistance. This paper presentspreliminary study results towards our final goal of the signalsource position estimation inside a human heart using smallnumbers of electrodes.
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Effects of Acoustic Resonance and Volute Geometry on Phase Resonance in a Centrifugal Fan
Yoshinobu Tsujimoto,Koichi Yonezawa,Hiroshi Tanaka,Peter Doerfler,Takayuki Suzuki,Keisuke Makikawa 한국유체기계학회 2013 International journal of fluid machinery and syste Vol.6 No.2
The effects of acoustic resonance and volute geometry on phase resonance are studied theoretically and experimentally using a centrifugal fan. One dimensional theoretical model is developed taking account of the reflection from the discharge pipe end. It was found that the phase resonance occurs, even with the effects of acoustic resonance, when the rotational speed of rotor-stator interaction pattern agrees with the sound velocity. This was confirmed by experiments with and without a silencer at the discharge pipe exit. The pressure wave measurements showed that there are certain effects of the cross-sectional area change of the volute which is neglected in the one dimensional model. To clarify the effects of area change, experiments were carried out by using a ring volute with a constant area. It was demonstrated that the phase resonance occurs for both interaction modes travelling towards/away from the volute. The amplitude of travelling wave grows towards the volute exit for the modes rotating towards the volute exit, in the same direction as the impeller. However, a standing wave is developed in the volute for the modes rotating away from the volute exit in the opposite direction as the impeller, as a result of the interaction of a growing wave while travelling towards the tongue and a reflected wave away from the tongue.
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Effects of Acoustic Resonance and Volute Geometry on Phase Resonance in a Centrifugal Fan
Tsujimoto, Yoshinobu,Tanaka, Hiroshi,Doerfler, Peter,Yonezawa, Koichi,Suzuki, Takayuki,Makikawa, Keisuke Korean Society for Fluid machinery 2013 International journal of fluid machinery and syste Vol.6 No.2
The effects of acoustic resonance and volute geometry on phase resonance are studied theoretically and experimentally using a centrifugal fan. One dimensional theoretical model is developed taking account of the reflection from the discharge pipe end. It was found that the phase resonance occurs, even with the effects of acoustic resonance, when the rotational speed of rotor-stator interaction pattern agrees with the sound velocity. This was confirmed by experiments with and without a silencer at the discharge pipe exit. The pressure wave measurements showed that there are certain effects of the cross-sectional area change of the volute which is neglected in the one dimensional model. To clarify the effects of area change, experiments were carried out by using a ring volute with a constant area. It was demonstrated that the phase resonance occurs for both interaction modes travelling towards/away from the volute. The amplitude of travelling wave grows towards the volute exit for the modes rotating towards the volute exit, in the same direction as the impeller. However, a standing wave is developed in the volute for the modes rotating away from the volute exit in the opposite direction as the impeller, as a result of the interaction of a growing wave while travelling towards the tongue and a reflected wave away from the tongue.
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