• 제목/요약/키워드: pulse wave velocity

검색결과 163건 처리시간 0.027초

Study on the frequency of self-excited pulse jet

  • Wang, Jian;Li, Jiangyun;Guan, Kai;Ma, Tianyou
    • International Journal of Fluid Machinery and Systems
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    • 제6권4호
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    • pp.206-212
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    • 2013
  • Self-excited pulse jet is a specific nozzle with a closed chamber which can change a continuous jet into a pulse one. Energy of the pulse jet can be output not only unevenly but also with multifrequency. With the peak pressure of pulse jet, the hitting power would be 2~2.5 times higher than that of continuous jet. In order to reveal the correlation between the self-excited pulse frequency and nozzle diameter ratio, nozzle spacing and operating pressure, the model of 3D unsteady cavitation model has been used. We found that with the same nozzle structure parameters and the different operating pressure, the self-excited frequency and the width of peak crest are different, but the wave profiles are similar. With FFT, we also found that the less bandwidth of amplitude in low frequency range will lead to the wider wave crest of outlet velocity in its time domain, and the larger force of the strike will be gained. By studying the St of self-excite nozzle, not only the frequency of a certain nozzle can be predicted, but also a nozzle structure with a certain frequency can be designed.

유산소 운동이 비만 여자대학생의 동맥맥파속도, 호흡순환계 및 신체조성에 미치는 영향 (Aerobic Exercise's Influence on Obese Female College Students'Arterial Pulse Wave Velocity, Cardiorespiratory Systems and Body Composition)

  • 김승석
    • 디지털융복합연구
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    • 제15권7호
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    • pp.407-414
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    • 2017
  • 본 연구는 융복합 유산소운동이 비만 여자대학생의 동맥맥파속도, 호흡순환계 및 신체조성에 미치는 영향을 규명하기 위해 D광역시 Y구에 위치한 D대학교 여자대학생을 대상으로 체지방율 수치가 30% 이상인자, 과거와 현재 특별한 질환이 없고, 규칙적인 신체활동 경험이 없는 26명을 선정하여 실험 목적과 내용을 충분히 설명한 후 참여 동의서를 받음으로써 최종 확정한 뒤, 운동집단(N=13), 통제집단(N=13)으로 무선배정 하고 12주간 유산소운동을 실시하였으며, 다음과 같은 결론을 얻었다. 첫째, 신체조성의 변화는 운동집단에서 체중, 체지방율, 복부지방율이 유의하게 감소를 보였다. 둘째, 호흡순환계의 변화는 운동집단에서 최대산소섭취량, 최대심박수, 최대환기량은 유의한 증가를 보였다. 셋째, 동맥맥파속도의 변화는 운동집단에서 상체(왼손, 오른손), 하체(왼발, 오른발)에서 유의한 감소를 보였다.

콘크리트 넓은 보의 상태평가를 위한 초음파 속도의 통계학적 분포에 대한 연구 (A Study on the Statistical Distribution of Ultrasonic Velocities for the Condition Evaluation of Concrete Wide Beam)

  • 윤영근;이인복;사민형;오태근
    • 한국안전학회지
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    • 제32권2호
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    • pp.98-104
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    • 2017
  • The ultrasonic pulse velocities of pressure, shear, and Rayleigh waves ( P-, S-, and R- waves) have been used for the condition evaluation of various concrete structures, but the statistical distribution according to the wave type has not been studied clearly in view of data reliability and validity. Therefore, this study analyzed the statistical distribution of P-, S-, R-wave velocities in concrete wide beams of $800{\times}3100mm$ (width ${\times}$ length) with a thickness of 300 mm. In addition, we investigated an experimental consistency by the Kolmogorov-Smirnov goodness-of-fit test. The experimental data showed that the R-, S- and P- wave velocities in order have better statistical stability and reliability for in situ evaluation because R- and S-waves are less sensitive to confinement and boundary conditions. Also, good correlations between wave velocities and strength and modulus of elasticity were found, which indicate them as appropriate techniques for estimating the mechanical properties.

초음파 분석을 이용한 촌관척 위치별 혈관의 특성연구 (Characteristic Study of the Pulse Position on CHON, KWAN and CHUCK Using the Ultrasonic Waves)

  • 이유정;이전;이혜정;유현희;최은지;김종열
    • 한국한의학연구원논문집
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    • 제13권3호
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    • pp.111-117
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    • 2007
  • The study aims to measure and analyze the thickness and depth of blood vessel on the pulse diagnosis locations and the blood velocity through the use of ultrasonic waves (LOGIQ5PRO, GE Medical, U.S.) in order to understand the structural difference of pulse diagnosis locations. The subjects included 44 healthy men and women(22.28${\pm}$2.62 age) considered normal in terms of Body Mass Index(BMI). The thickness and depth of the blood vessel and the blood velocity were measured three times on CHON, KWAN and CHUCK to obtain the average value. Results showed there is a statistically significant difference among the variables measured on CHON, KWAN and CHUCK. A difference according to gender was also observed. This explains why an oriental medical doctor can tell the difference in pulses depending on the location of CHON, KWAN and CHUCK. In addition, the difference in pressure between CHON and KWAN was higher than that in pressure between KWAN and CHUCK. The findings explain why oriental medical doctors take pulses by dividing CHON, KWAN and CHUCK in the short length of the three fingers. It can be used to develop a pulse diagnosis device enabling accurate measurement according to the characteristics of blood vessel structure based on where the pulse is taken. Furthermore, the results can be used as basic data for the development of a pulse diagnosis simulator.

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A Wrist Watch-type Cardiovascular Monitoring System using Concurrent ECG and APW Measurement

  • Lee, Kwonjoon;Song, Kiseok;Roh, Taehwan;Yoo, Hoi-jun
    • JSTS:Journal of Semiconductor Technology and Science
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    • 제16권5호
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    • pp.702-712
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    • 2016
  • A wrist watch type wearable cardiovascular monitoring device is proposed for continuous and convenient monitoring of the patient's cardiovascular system. For comprehensive monitoring of the patient's cardiovascular system, the concurrent electrocardiogram (ECG) and arterial pulse wave (APW) sensor front-end are fabricated in $0.18{\mu}m$ CMOS technology. The ECG sensor frontend achieves 84.6-dB CMRR and $2.3-{\mu}Vrms$-input referred noise with $30-{\mu}W$ power consumption. The APW sensor front-end achieves $3.2-V/{\Omega}$ sensitivity with accurate bio-impedance measurement lesser than 1% error, consuming only $984-{\mu}W$. The ECG and APW sensor front-end is combined with power management unit, micro controller unit (MCU), display and Bluetooth transceiver so that concurrently measured ECG and APW can be transmitted into smartphone, showing patient's cardiovascular state in real time. In order to verify operation of the cardiovascular monitoring system, cardiovascular indicator is extracted from the healthy volunteer. As a result, 5.74 m/second-pulse wave velocity (PWV), 79.1 beats/minute-heart rate (HR) and positive slope of b-d peak-accelerated arterial pulse wave (AAPW) are achieved, showing the volunteer's healthy cardiovascular state.

두 대역 상반된 스윕방향 hyperbolic frequency modulation 펄스로 수중물체 시선속도추정 기법 및 성능분석 (Underwater object radial velocity estimation method using two different band hyperbolic frequency modulation pulses with opposite sweep directions and its performance analysis)

  • 조점군;정의철
    • 한국음향학회지
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    • 제42권1호
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    • pp.25-31
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    • 2023
  • 능동소나를 이용하여 수중물체의 속도를 추정하려면 Continuous Wave(CW) 펄스를 이용하는 것이 일반적이나, 수중물체의 속도가 느리고 근거리의 해양에서는 잔향음의 영향으로 수중물체의 속도 추정이 용이하지 않다. 2017년도에 Wang 연구진은 이를 극복하고자 수중물체의 속도에 의한 도플러 변이에 둔감한 광대역 신호인 Hyperbolic Frequency Modulation(HFM) 펄스 두 개를 상반된 스윕방향으로 이용하였다. 두 펄스 간 송신 시간간격과 탐지시간 차이의 변화를 통하여 수중물체 속도 추정이 가능하다는 것을 시뮬레이션으로 제시하였다. 하지만 동일한 대역을 이용하므로 상호상관성에 의해서 수중물체 탐지 성능이 영향을 받을 수 밖에 없다. 상호상관성에 의한 수중물체 탐지 성능저하를 방지하기 위하여 대역이 분리된 상반된 스윕방향의 두 HFM 펄스 이용을 제안한다. 본 논문에서는 상반된 스윕방향의 두 대역 HFM을 이용하여 수중물체의 시선속도 추정에 관한 이론을 도출하였고, 펄스길이와 대역폭이 1 s와 400 Hz인 HFM 펄스로 시뮬레이션을 수행하였다. 제안한 방법을 이용하여 수중물체의 시선속도를 추정하면 약 6 %의 오차로 표적 속도 추정이 가능하다는 것을 시뮬레이션을 통하여 확인하였다.

Reproducibility of Regional Pulse Wave Velocity in Healthy Subjects

  • Im Jae-Joong;Lee, Nak-Bum;Rhee Moo-Yong;Na Sang-Hun;Kim, Young-Kwon;Lee, Myoung-Mook;Cockcroft John R.
    • International Journal of Vascular Biomedical Engineering
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    • 제4권2호
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    • pp.19-24
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    • 2006
  • Background: Pulse wave velocity (PWV), which is inversely related to the distensibility of an arterial wall, offers a simple and potentially useful approach for an evaluation of cardiovascular diseases. In spite of the clinical importance and widespread use of PWV, there exist no standard either for pulse sensors or for system requirements for accurate pulse wave measurement. Objective of this study was to assess the reproducibility of PWV values using a newly developed PWV measurement system in healthy subjects prior to a large-scale clinical study. Methods: System used for the study was the PP-1000 (Hanbyul Meditech Co., Korea), which provides regional PWV values based on the measurements of electrocardiography (ECG), phonocardiography (PCG), and pulse waves from four different sites of arteries (carotid, femoral, radial, and dorsalis pedis) simultaneously. Seventeen healthy male subjects with a mean age of 33 years (ranges 22 to 52 years) without any cardiovascular disease were participated for the experiment. Two observers (observer A and B) performed two consecutive measurements from the same subject in a random order. For an evaluation of system reproducibility, two analyses (within-observer and between-observer) were performed, and expressed in terms of mean difference ${\pm}2SD$, as described by Bland and Altman plots. Results: Mean and SD of PWVs for aorta, arm, and leg were $7.07{\pm}1.48m/sec,\;8.43{\pm}1.14m/sec,\;and\;8.09{\pm}0.98m/sec$ measured from observer A and $6.76{\pm}1.00m/sec,\;7.97{\pm}0.80m/sec,\;and\;\7.97{\pm}0.72m/sec$ from observer B, respectively. Between-observer differences ($mean{\pm}2SD$) for aorta, arm, and leg were $0.14{\pm\}0.62m/sec,\;0.18{\pm\}0.84m/sec,\;and\;0.07{\pm}0.86m/sec$, and the correlation coefficients were high especially 0.93 for aortic PWV. Within-observer differences ($mean{\pm}2SD$) for aorta, arm, and leg were $0.01{\pm}0.26m/sec,\;0.02{\pm}0.26m/sec,\;and\;0.08{\pm}0.32m/sec$ from observer A and $0.01{\pm}0.24m/sec,\;0.04{\pm}0.28m/sec,\;and\;0.01{\pm}0.20m/sec$ from observer B, respectively. All the measurements showed significantly high correlation coefficients ranges from 0.94 to 0.99. Conclusion: PWV measurement system used for the study offers comfortable and simple operation and provides accurate analysis results with high reproducibility. Since the reproducibility of the measurement is critical for the diagnosis in clinical use, it is necessary to provide an accurate algorithm for the detection of additional features such as flow wave, reflection wave, and dicrotic notch from a pulse waveform. This study will be extended for the comparison of PWV values from patients with various vascular risks for clinical application. Data acquired from the study could be used for the determination of the appropriate sample size for further studies relating various types of arteriosclerosis-related vascular disease.

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손가락 끝 용적맥파를 이용한 자세변화에 따른 맥파 신호에 관한 연구 (On Study of Pulse Wave Signal According to Postural Change Using Finger Plethysmography)

  • 최병철;김철한;정동근;서덕준
    • 대한의용생체공학회:학술대회논문집
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    • 대한의용생체공학회 1998년도 추계학술대회
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    • pp.125-126
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    • 1998
  • Pulse conduction velocity is determined by areterial compliance, which is changed by lateral pressure of arterial wall. Hydrostatic pressure of the limb vessel is changed by body position, especially in elevated arm. The arterial pulse in the finger causes the blood volume to change, changing the optical density of the blood. Photoplethysmograph of index finger was obtained by LED and phototransistor. Pulse transmission time(PTT) was measured by the interval between the peak of ECG R wave and the peak of the finger plethysmogram. PTT was increased by upward position of arm, and decreased by downward position of the arm compared to horizontal position. This result suggests that relationship between finger plethysmography and postural change could be applied to evaluate clinical cardiovascular status.

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Association of Uric Acid Levels with Arterial Stiffness in Korean Women and Non-smoking Men

  • Sull, Jae Woong;Koh, Eun Na;Cho, Sung Kweon;Bae, Hyung-Joon;Jee, Sun Ha
    • 대한의생명과학회지
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    • 제23권3호
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    • pp.201-207
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    • 2017
  • Measuring the pulse wave velocity (PWV) is a non-invasive method for evaluating the stiffness of the vessel wall. While previous studies investigated the association of uric acid level with arterial stiffness, most did not consider smoking status and obesity as covariates. The objective of this study was to investigate the relationship between uric acid levels and arterial stiffness, considering smoking status and obesity. We studied 3390 subjects (1940 males and 1450 females). Abnormal PWV was also defined as the highest quartile of values in the subjects. Data were analyzed using Pearson correlation, t-test, and multiple regression analysis. Approximately 41.9% of men and 3.7% of women were current smokers. Prevalence of hypertension was 11.4% in men and 7.0% in women. In women, hyperuricemia was associated with abnormal PWV (OR 1.58; 95% CI 1.03~2.43). Hyperuricemia was also associated with abnormal PWV (OR 2.37; 95% CI 1.01~5.59) in non- or light male smokers with normal blood pressure. This study suggests that uric acid is associated with arterial stiffness in women and non-smoking men.