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마이크로 컴퓨터를 이용한 실시간 ECG 자동진단 알고리즘
윤형로,최경훈 대한의용생체공학회 1985 의공학회지 Vol.6 No.1
The cardiac activation process using three dimensional ventricular model is simulated.To study this theme, we constructed a cardiac ventricular model and simulated the cardiac activation process using the action potential duration and the activation time. The cardiac ventricular model is generated by the logical combination of the elliptic equations. The action potential duration could be obtained from the fact that it is linearly distributed between model cells. The cardiac activation process was simulated by the law of "all-or-none" Based on the activation time and the action potential do-ration the cardiac potential at the arbitrary time after the activation of the model cell was computed. To test the validity of model, the comparison of the results of model simulation with the physiological data was performed. In conclusion, this model shows the simular results which is comparable to the real conduction of the cardiac excitation.xcitation.
윤형로,전석환,엄대자,오중환 연세대학교의과대학 2010 Yonsei medical journal Vol.51 No.3
Purpose: Photoplethysmography (PPG) is a noninvasive optical technology that detects changes in blood volume in the vascular system. This study aimed to investigate the possibilities of monitoring the cardiovascular system status by using PPG. Materials and Methods: Forced hemodynamic changes were induced using cardiac stimulants; dopamine and epinephrine, and PPG components were recorded by a noninvasive method at the peripheral blood vessels. The results were compared among 6 dogs. Endotracheal intubation was performed after an intramuscular injection of 25 mg/kg ketamine sulfate, and anesthesia was maintained with 2% enflurane. After stabilizing the animals for 15 min, 16 mg/mL diluted dopamine was injected into a vein for 2 min at 20 μg/kg˙ min-1 by using an infusion pump. Thereafter, the infusion pump was stopped, and 1 mg epinephrine was injected intravenously. Fluid administration was controlled to minimize preload change in blood pressure. Results: After stimulant administration, systolic blood pressure (SBP) and diastolic blood pressures (DBP) increased. The direct current (DC) component, which reflects changes in blood volume, decreased while the alternating current (AC) component, which reflects changes in vascular compliance and resistance, increased. The correlation coefficient between SBP and the foot of the DC component was 0.939 (p < 0.01), while it was 0.942 (p < 0.01) for DBP and the peak of the DC component. The AC component could predict the increase in vascular resistance from a stable pulse blood volume, even with increased pulse pressure. Conclusion: These results support the possibility that PPG components may be used for easy and noninvasive measurement of hemodynamic changes in the cardiovascular system.
윤형로,김광준 대한의용생체공학회 1991 의공학회지 Vol.12 No.4
This research has reported that the selection and assessment of treatment in anxiety disorders depend to a large extend on patient reports of somatic symptomatology. However, the correspondence between such reports and actual physiological data Is unknown as the physiological measures used were taken in laboratory. The purpose of the ambulatory momboring device is, therefore, to present for analysis physiological data derived from the sub jects during their daily activities. The physiological parameters of interest are heart rate, respiratory rate, skin conductance level/response, skin temperature, and activity level. This device had an microcomputer based data acquisition unit, Interfaced to it for the purpose of data collection. The data is collected usually over a period of 12 hours. The data from the ambulatory monitoring device can be used to assess the psychophysiology of anxiety in the field. The data from the device will also reveal if patients who report different sets of symptoms differ physiologically too. Thls will help physicians for the right kind of treatment and also solve the many uncertainties that have existed thus far in quantizing anxiety.
윤형로,Uk-jin Yoon,Yeon-Sik Noh 대한의용생체공학회 2011 Biomedical Engineering Letters (BMEL) Vol.1 No.2
Purpose Wearable electrocardiogram (ECG) systems are exposed to more noises than the general ECG systems,because of the high impedance between electrodes and the skin and the need to acquire ECG data during exercise or in daily life. The purpose of this study was to enhance heart rate detection by optimizing electrode and signal processing in a wearable system during high-intensity exercise. Methods To create an optimal electrode condition, we quantitatively measured the change in noise according to a change in pattern of textile electrodes by using 3 textile electrodes with the same material quality but different patterns. We also measured the degree of skin hydration by using an MPA5 (CK Electronics, Germany) to obtain the optimal condition between electrodes and skin. To accurately detect the QRS complex, use of an improved algorithm based on a wavelet, which has strong noise tolerance, was suggested. Results We obtained root-mean-square (RMS) values that were expected to be similar to those measured with the Ag-AgCl electrode at the point of >120% of skin hydration. The QRS complex detection rate of the wavelet method that was suggested in this study was compared to that of an adaptive filter and mathematical morphology operator. We used the data collected during actual exercise performed at 15 km/h. The QRS complex detection rate of the proposed algorithm was 99.9%. Conclusions Through optimization of the wearable system that was suggested in this study, collection of a more accurate heart rate value is expected. In addition, the influence of noise could be minimized in the wearable system.