• Clinical and Experimental Pediatrics
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• 제46권10호
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• pp.983-988
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• 2003

목 적 : 실신은 소아에서 가장 흔한 증상이지만 기전은 잘 알려져 있지 않다. 증가된 미주신경의 활동과 감소된 교감신경의 자극이 저혈압, 서맥을 일으키고 마침내는 의식 소실을 초래한다. 이 연구의 목적은 혈관미주 신경성 실신으로 진단된 소아에서 기립경사 검사를 하는 동안 뇌 도플러 초음파를 실시하여 실신 전후의 뇌혈류 속도와 혈압, 심박동수 변화를 측정하고자 하였다. 방 법 : 실신의 과거력을 갖고 있는 64명의 소아를 대상으로 혈압을 10분간 안정 후와 15분 동안 기립 후에 측정하였고, 기립 경사 검사는 $80^{\circ}$에서 45분간 시행하였다. $80^{\circ}$ 각도의 경사 테이블에서 소아를 5분 간격으로 45분 동안 혈압, 심박동수, 산소 포화도를 측정하였다. 기립경사 검사를 하는 동안 실신이나 실신 전 증상이 나타난 소아에서는 검사를 중단하였다. 12-유도 심전도, 뇌파 검사, 심장 초음파를 시행하였다. 기립경사 검사에서 양성으로 나온 10명의 소아에서 Acouson 128XP/10 model 초음파 기기를 이용하여 중 대뇌동맥 혈류 속도, pulsatility 지수, time velocity integral, 혈압, 심박동수, 산소포화도 등을 측정하였다. 결 과 : 기립경사 검사에서 31.3%(20/64)의 양성률을 보였다. 검사 동안에 혈압과 맥박은 감소되지 않았고 뇌혈류 속도와 integral은 유의하게 감소되었다. 결 론: 뇌혈류 속도는 혈압이나 심박동수가 감소하기 전에 미리 감소하므로 실신 전 증상을 미리 예측할 수 있다. 뇌혈류의 자율 조절의 장애가 혈관미주 신경성 실신의 병인론에 중요한 역할을 하리라 생각된다.

• 한국가시화정보학회지
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• 제8권1호
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• pp.46-52
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• 2010

In the present study, we employed the confocal laser scanning microscopy (CLSM) system to visualize the blood flow field with $1{\times}1{\mu}m^2$ spatial resolution. Based on the confocal microscopic image of red blood cells (RBCs), we performed the velocity vector field measurement and evaluated characteristics of cell migration from the cell depleted layer thickness calculation. The rat and mouse's blood were supplied into a micro glass tubes in vitro. The line scanning rate of confocal microscopy was 15 kHz for a $500{\times}500$ pixels image. As a result, the red blood cell itself can be used as a tracer directly without any kind of invasive tracer particle to get the velocity vector field of blood flow by performing particle image velocimetry (PIV) technique.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.504-512
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• 2002

Bileaflet mechanical valves have the complications such as hemolytic and thromboembolic events, leaflet damage, and leaflet break. These complications are related with the fluid velocity and shear stress characteristics of mechanical heart valves. This fact makes clear the importance of determining the fluid velocity and shear stress characteristics of mechanical heart valves, and requires a detailed understanding of these system properties and further substantial research. The first aim of current study is to introduce fluid-structure interaction method for calculation of unsteady and three-dimensional blood flow through bileaflet valve and leaflet behavior interacted with its flow, and to overcome the shortness of previous studies, where the leaflet motion has been ignored or simplified, by using FSI method. To accomplish this goal, a finite volume computational fluid dynamics code and a finite element structure dynamics code have been used concurrently to solve the flow and structure equations, respectively, to investigate the interaction between the blood flow and leaflet. Physiologic ventricular and aortic pressure waveforms were prescribed as flow boundary conditions. The interaction of aortic flow and valve motion were computed.

• 대한중풍순환신경학회지
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• 제6권1호
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• pp.45-53
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• 2005

Objective : This study was performed to examine the relationship between cerebral blood vessel with meridian by using Transcranial Doppler Ultrasonography(TCD) Method : Monitoring of TCD was examined in 10 healthy people in their twenties (mean age was 26.5±1.00). Each examination was performed before & after acupuncture. Three Meridian were tested. Those were Stomach Meridian, Bladder Meridian & Gallbladder Meridian. Maximum velocity and Mean velocity were analyzed from TCD on different vessel. Result : The results showed significant(p<0.05; Wilcoxon signed rank test) change in some cerebral blood flow after acupuncture. Conclusion : There was the relationship between Meridian and cerebral blood vessel.

• 대한기계학회논문집B
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• 제20권11호
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• pp.3607-3619
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• 1996

Experimental and numerical studies for three-dimensional pulsatile flows are conducted to investigate the flow characteristics in the bifurcated tubes. Velocity measurements in experimental study were made by both Pulsed Doppler Ultrasound(PDU) machine and Laser Doppler Anemometer(LDA) system. Glycerin is used for experimental study. Experimental results are used to verify the results of the numerical simulation. Flow characteristics of Newtonian fluid and blood in the bifurcated tubes under the steady and pulsatlie flows are numerically investigated. Finite volume method is employed for three-dimensional numerical simulations. Blood is considered as a non-Newtonian fluid and the constitutive equation of blood is used for the numerical analysis. Numerical analyses are focused on the flow patterns for various branch angles ranging from 30.deg. to 90.deg. and diameter ratios such as 1.0, 0.8, and 0.6. Pulsatile flow characteristics of blood are compared with those of Newtonian fluid. Parameter effects on axial velocity, pressure and wall shear stress distribution along the bifurcated tubes are discussed in terms of the branch angle, diameter ratio, and Reynolds number.

• Imaging Science in Dentistry
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• 제48권3호
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• pp.153-160
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• 2018

Purpose: This study aimed to assess the reliability of ultrasonography (US) in comparison with cone-beam computed tomography (CBCT) as a tool for monitoring the healing of jaw lesions. Materials and Methods: Twenty-one radiolucent lesions in jaws referred to the Oral Surgery Department at our institution were selected for this study. All lesions underwent CBCT and US examinations. The anteroposterior, superoinferior, and mesiodistal dimensions of the lesions were measured on CBCT and US images before surgery and at 6 months after surgery. The dimensions were compared between the US and CBCT images. Blood-flow velocity around the lesions was measured by color Doppler before surgery and at 1 week and 6 months after surgery to assess the capability of US to show changes in blood-flow velocity around the lesion. Results: Before surgery, there were no significant differences between US and CBCT in the mesiodistal and anteroposterior dimensions, although a significant difference was found in the superoinferior dimension (P<.05). However, at 6 months after surgery, significant differences were found between US and CBCT in all dimensions, and it is likely that the US measurements more accurately reflected the extent of healing. The average blood-flow velocity increased at 1 week after surgery (5.84 cm/s) compared with the velocity before surgery (4 cm/s) (P<.05). Then, at 6 months after surgery, the blood-flow velocity significantly decreased (3.53 cm/s) compared to the velocity measured at 1 week after surgery (P<.05). Conclusion: US with color Doppler was confirmed to be a more efficient tool than CBCT for monitoring bone healing.

• 동의신경정신과학회지
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• 제20권1호
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• pp.199-214
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• 2009

Objectives : This study was performed to change of blood flow in In-Young(ST9) after treatment on chronic daily headache patients. Methods : Monitoring of TCD was examined in 10' s chronic daily headache patients before and after treatment. Mean velocity flow, systolic velocity and pulsatility index were analyzed from TCD at In-Young(ST9). The patients was laid for 20 minutes before treatment and also for treatment. Results : The results showed a significant(p<0.05: Paired T-test) decrease in mean velocity flow and systolic velocity. but there were no significant differences in pulsatility index. Conclusions : These results suggest that there were significant change on blood flow in In-young of chronic daily headache patients.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.705-708
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• 1988

Ultrasound Doppler Diagnostic System utilizes the Doppler effect for measurement of blood velocity. The sign of the Doppler frequency shift represents blood flow direction. Pulsed Doppler System uses Phase detector and zerocrossing method to produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction in the time domain, had been fabricated. But time-domain analyzing such as audio evaluation and zerocrossing detection for instantaneous and mean frequency measurement doesn't, provide both an accurate and quantitative result. Therefore, it is necessary to adopt frequency domain technique to improve system performance. In this paper, we describe a unit which is composed of Pulsed Doppler System and real-time spectrum analyzer (installed TMS 32010 DSP Chip). This unit shows time-dependent spectrum variation and mean velocity of blood Signal.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.709-712
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• 1988

Ultrasonic Doppler Diagnostic System utilizes the Doppler effect for measurement of blood velocity. The sign of the Doppler frequency shift represents blood flow direction. CW(Continuous-Wave) Doppler System uses quadrature detection and phase rotation method to produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction in the time-domain, had been fabricated. But time-domain analyzing such as audio evaluation and zero- crossing detection for instantaneous and mean frequnecy measurement do not provide both an accurate and quantitative result. Therefore, it is necessary to adopt frequency-domain technique to improve system performance. In this paper, we describe a unit which is composed of CW Doppler System and real-time spectrum analyzer (installed TMS 32010 DSP Chip). This unit shows time-dependent spectrum variation and mean velocity of Blood signal.

• 전기학회논문지
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• 제67권7호
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• pp.917-927
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• 2018

High blood pressure causes various cardiovascular diseases and is associated with mortality. Periodic self-monitoring and recording of blood pressure is very helpful in preventing the occurrence of secondary diseases caused by hypertension. However, existing cuff-type blood pressure monitors have many limitations. As an alternative of that, a method of estimating the blood pressure by measuring the velocity change of the blood flow using the photo plethysmography is widely known. However, photo plethysmography have a low correlation with blood flow. So, we will propose an algorithm for estimating blood pressure using the relationship between velocity change of blood flow measured by magnetic field instead of photo plethysmography and electrocardiogram. For this purpose, First, we analyzed the correlation between photo plethysmography and magneto plethysmography. the correlation between MPG and PPG was r = 0.9449. Second, we compared estimated blood pressure and measured blood pressure. In the four experiment each result was r = 0.5737, r = 0.7863, r = 0.5669, and r = 0.7445.