• 대한의용생체공학회:의공학회지
• /
• 제28권4호
• /
• pp.503-511
• /
• 2007

Heart rate variability(HRV) is the clinical consequence of various influences of the autonomic nervous system(ANS) on heart beat. HRV can estimate the potential physiologic rhythm from the interval between consecutive beats(RR interval or HRV data), but cardiovascular system governed by ANS is in relation to respiration and autonomic regulation. It is known as RSA representing respiration-related HR rhythmic oscillation. Because the mechanism linking the variability of HR to respiration is complex, it has so far been unknown well. In this paper, we tried to evaluate 5-min RR interval segments under control of respiration in order to find out a proper respiration rate that can estimate the ANS function. 10 healthy volunteers were included to evaluate 5-min HRV data under 4 different respiration-controlled environments; 0.03Hz, 0.1Hz, 0.2Hz, and 0.4Hz respiration. HRV data were analyzed both in the frequency and the time domain, with cross-correlation coefficient(cross-coeff.) for HRV and respiration signal. The results showed maximum cross-coeff. of 0.84 at 0.1 Hz and minimum that of 0.16 at 0.4Hz respiration. Cross-coeff was decreased at a faster rate from 0.1Hz respiration. All mean SDNN, RMSSD, and pNN50 of time domain measures were 108.7ms, 71.85ms, and 28.47%, respectively, and LF, HF, and TP of frequency domain measures were $12,722ms^2,\;658.8ms^2$, and $7,836.64ms^2$ at 0.1Hz respiration, respectively. In conclusion, 0.1Hz respiration was observed to be very meaningful from time domain and frequency domain analysis in relation to respiration and autonomic regulation of the heart.

• 디지털콘텐츠학회 논문지
• /
• 제8권3호
• /
• pp.355-363
• /
• 2007

학습자의 성격유형에 따른 학습 선호도는 학습 성취의 주요 인자 중의 하나이다. 따라서 학습자는 자신의 성격 유형과 다른 콘텐츠로 학습을 하게 되면 스트레스가 증가하여 혈압이나 심박동수에 변화가 나타나게 된다. 본 연구에서는 학습자의 비선호도를 측정하기 위해서 스트레스 량 측정에 사용되는 주파수 영역 정보를 이용하였다. 먼저, 13명의 유치원 아동들을 MBTI 성격유형의 감각/직관의 두 유형으로 파악하고 이들에게 동일한 학습 콘텐츠를 10분간 제시한 후, 이를 학습하는 동안 측정된 심전도 신호를 심박변동신호(heart rate variability: HRV) 신호로 재구성하였다. 이 HRV 신호를 주파수로 변환한 후에 저주파(LF: low frequency), 중간 주파(MF: middle frequency), 그리고 고주파(HF: high frequency) 영역으로 분할하고, 각 주파수 영역비를 비교하여 학습자의 성격 유형에 따라 학습 콘텐츠에 대한 선호도가 달라지는 지 여부를 알아보았다. 실험 결과는 아동들은 자신의 성격 유형에 따라 각기 다른 학습 콘텐츠를 선호한다는 사실을 보여준다.

• 정보통신설비학회논문지
• /
• 제11권2호
• /
• pp.29-33
• /
• 2012

ECG widely used in cardiac function test is a graph that is recorded by measuring the electrical impulses occurred in the heart. Normal ECG has the form of similar sections that are repeated, and each section has the information occurred in a heart beat. Thus, In order to make the correct diagnosis, correct grasp of the sections and formed analysis must be done. In this research, a system that detects the sections of ECG is proposed. The system is based on ECG stored in the form of files. The ECG can easily have a noise caused by an outside factor. The noise of ECG is easily caused by external factors. Through a band-pass filter, it can be removed. and then, to get this ECG without a noise, interval detection algorithm using R-peak is applied. The clean, intuitive interface will help the above functions to be used without any difficulties.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1990년도 춘계학술대회
• /
• pp.7-8
• /
• 1990

In this study, a new ensemble average technique was developed to measure cardiac output during treadmill exercise. Each dZ/dt peak (C point) was used as a starting point for ensemble averaging, instead of conventionally used R wave of ECG in order to prevent the peak dZ/dt waveform from blurring. In ease of using R wave as a reference, time interval from R wave to the peak of dZ/dt varies for each heart beat. Stroke volume, heart rate, and cardiac output of five male were successfully measured with Balke protocol using the new ensemble average technique.

• The Korean Journal of Physiology
• /
• 제9권1호
• /
• pp.39-43
• /
• 1975

The effects of histamine on cardiovascular system in 6 dogs were analyzed. Mongrel dogs, 10 to 16 kg in body weight, were anesthetized with Nembutal (30 mg/kg) and arterial blood pressure, heart rate, central venous pressure, electrocardiogram were recorded and measured plasma potassium concentration. Histamine $(100{\mu}g/ml)$ was infused slowly at the rate of 0.25 ml/min through the external jugular vein until BP was 80/60 and maintained restored BP for more than 5 min. The process repeated $4{\sim}5$ times. At each time before and after infusion every items were recorded and measured. 1. Arterial blood pressure was 142/105 (mean 117) mmHg in control and decreased to 90/60 68) after histamine infusion. 2. Heart rate changed from 175 beat/min to 150 and central venous pressure from 6.2 to 5.2 cm $H_2O$. 3. Plasma potassium concentration was 4.3 mEq/L and slightly increased to 4.7 mEq/L but it was not significant statistically. 4. Most characteristic changes revealed in EKG especially in T-waves. Height, Width, Steepness, and Slimness were increased $1.5{\sim}3.7$ times than control level and Pointedness decresed 0.5 times than before.

• Journal of Advanced Marine Engineering and Technology
• /
• 제37권2호
• /
• pp.149-155
• /
• 2013

혈류 유동 연구를 위해서는 심장의 맥동 유동을 만들어 내는 것이 중요하다. 본 연구에서는 동맥혈류의 유동 해석을 위해 새롭게 설계된 심장 박동 모사 맥동펌프의 제작 및 그 성능에 관하여 시험을 수행하였다. 피스톤 펌프를 이용한 기본몸체 설계를 수행하였고 직류모터와 엔코더를 사용하여 회전수와 가속비를 설정할 수 있도록 하였으며, 시험결과는 전 영역에서 맥동 유동의 분포를 잘 따르고, 반복되는 맥동 주기의 편차도 작게 나타남을 확인하였다.

• Journal of Chest Surgery
• /
• 제13권4호
• /
• pp.462-469
• /
• 1980

Here, I and wer report the results of our studying about; 1. The length of esophagus and sphincters; 2. Resting pressure of upper sphincter, upper esophagus, mid-esophagus, lower esophagus and lower sphincter; 3. Pressure changes in swallowing at these points of esophagus; 4. Resting and swallowing pressure curves in these points in 50 normal Korean adults. In addition to these we wbserved pressure inversion point, slow and fast components of phasic pressure which are originating from respiration and heart beat. And we studied transportation time and speed of peristalsis. The speed of peristalsis is faster in the lower esophagus than in the upper. I can probalby be proud in the results of these study because these will become a standard criteria in the further evaluation of esophageal functional disturbances in such lesions as; Achalasia, Hiatal hernia, Esophageal canceer, Scleroderma, diverticula.

• Korea-Australia Rheology Journal
• /
• 제21권2호
• /
• pp.119-126
• /
• 2009

A numerical analysis is performed to investigate the effect of rotation on the blood flow characteristics with four different angular velocities. The artery has a cylindrical shape with 50% stenosis rate symmetrically distributed at the middle. Blood flow is considered a non-Newtonian fluid. Using the Carreau model, we apply the pulsatile velocity profile at the inlet boundary. The period of the heart beat is one second. In comparison with no-rotation case, the flow recirculation zone (FRZ) contracts and its duration is reduced in axially rotating artery. Also wall shear stress is larger after the FRZ disappears. Although the geometry of artery is axisymmetry, the spiral wave and asymmetric flow occur clearly at the small rotation rate. It is caused that the flow is influenced by the effects of the rotation and the stenosis at same time.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 춘계학술발표대회
• /
• pp.10.1-10.1
• /
• 2011

Energy harvesting technologies converting external sources (such as thermal energy, vibration and mechanical energy from the nature sources of wind, waves or animal movements) into electrical energy is recently a highly demanding issue in the materials science community for making sustainable green environments. In particular, fabrication of usable nanogenerator attract the attention of many researchers because it can scavenge even the biomechanical energy inside the human body (such as heart beat, blood flow, muscle stretching, or eye blinking) by converging harvesting technology with implantable bio-devices. Herein, we describe procedure suitable for generating and printing a lead-free microstructured $BaTiO_3$ thin film nanogenerator on plastic substrates to overcome limitations appeared in conventional flexible ferroelectric devices. Flexible $BaTiO_3$ thin film nanogenerator was fabricated and the piezoelectric properties and mechanically stability of ferroelectric devices were characterized. From the results, we demonstrate the highly efficient and stable performance of $BaTiO_3$ thin film nanogenerator and the integration of bio-eco-compatible ferroelectric materials may enable innovative opportunities for artificial skin and energy harvesting system.

• 한국임상수의학회지
• /
• 제21권3호
• /
• pp.298-301
• /
• 2004

Pregnancy diagnosis by ultrasonography was performed for both pregnant and non-pregnant Asiatic black bears which were being under hibernation. Pregnancy was diagnosed for a pregnant bear by detecting images of heart-beat and vertebrae on ultrasonograph. Serum progesterone levels were measured for both pregnant and non-pregnant bears. The level of serum progesterone was 5.79 ng/ml for a pregnant bear and 0.76 ng/ml for a non-pregnant bear, respectively, thereby it was considered that measurement of serum progesterone level can be also useful for pregnancy diagnosis for Asiatic black bear.