• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.149-154
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• 2015

Biometric techniques for authentication using body parts such as a fingerprint, face, iris, voice, finger-vein and also photoplethysmography have become increasingly important in the personal security field, including door access control, finance security, electronic passport, and mobile device. Finger-vein images are now used to human identification, however, difficulties in recognizing finger-vein images are caused by capturing under various conditions, such as different temperatures and illumination, and noise in the acquisition camera. The human photoplethysmography is also important signal for human identification. In this paper To increase the recognition rate, we develop camera based identification method by combining finger vein image and photoplethysmography signal. We use a compact CMOS camera with a penetrating infrared LED light source to acquire images of finger vein and photoplethysmography signal. In addition, we suggest a simple pattern matching method to reduce the calculation time for embedded environments. The experimental results show that our simple system has good results in terms of speed and accuracy for personal identification compared to the result of only finger vein images.

• Journal of Biomedical Engineering Research
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• v.35 no.5
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• pp.125-131
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• 2014

The purpose of this study is to verify the utility of reflected photoplethysmography sensor using two green light emitting diodes that influenced by ambient light. Recently it has been studied that green light emitting diode is suitable for light source of reflected photoplethysmography sensor at low temperature and high temperature. Another study showed that, green light is better for monitoring heart rate during motion than led light. However, it has a bad characteristic about ambient light noise. To verify the utility of reflected photoplethysmography sensor using green light emitting diode, this study measures the photoplethysmography signal that is distorted by ambient light and will propose a solution. This study has two parts of research method. One is measurement system that composed sensor and board. The sensor is made up PE-foam and Non-woven fabric for flexible sensor. The photoplethysmography signal is measured by measurement board that composed high-pass filter, low-pass filter and amplifier. Ambient light source is light bulb and white light emitting diode that has three steps brightness. Photoplethysmography signal is measured with lead II electrocardiography signal at the same time and it is measured at the finger and radial artery for 1 minute, 1000 Hz sampling rate. The lead II electrocardiography signal is a standard signal for heart rate and photoplethysmography signal that measured at the finger is a standard signal for waveform. The test is repeated 3 times using three sensor. The data is processed by MATLAB to verify the utility by comparing the correlation coefficient score and heart rate. The photoplethysmography sensor using two green light emitting diodes is shown better utility than using one green light emitting diode and red light emitting diode at the ambient light. The waveform and heart rate that measured by two green light emitting diodes are more identical than others. The amount of electricity used is less than red light emitting diode and error peak detectability factor is the lowest.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.11 no.1
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• pp.82-104
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• 2007

Purpose: We performed this study to examine the effect of controlled respiration on cardiovascular system in healthy adult subjects using impedance cardiography and photoplethysmography. Materials and Methods: This study had performed on 74 subjects, which were healthy men and women without a experience of respiration practice. Using the instruments for impedance cardiography and photoplethysmography, parameters of each subject had been measured after each controlled respirations which were natural respiration, controlled natural respiration (I:E=1.1.6), longer inspiration(I:E=3:3), and longer expiration(I:E=2:4). The measured parameters of impedance cardiography and photoplethysmography were processed statistically by one-way repeated ANOVA. Results: 1. HR and CI of impedance cardiography were decreased significantly during controlled respiration comparing with the result of basal state(the state of enough break). There was no significant difference among the results of controlled respiration. 2. PEP of impedance cardiography had no significant difference among the result of basal state and the results of controlled respiration(p=0.059). 3. VI of impedance cardiography had significant differences among the result of basal state and the results of controlled respiration, and decreased continuously through the controlled respiration. 4. b/a of photoplethysmography had no significant difference among the result of basal state and the results of controlled respiration(p=0.554). 5. c/a of photoplethysmography were decreased significantly during controlled respiration comparing with the result of basal state. There was no significant difference among the results of controlled respiration. 6. d/a of photoplethysmography had significant differences among the results of the controlled respiration decreasing continuously through the controlled respiration and had no significant difference between the result of basal state and the result of natural respiration. 7. AGI of photoplethysmography had significant differences among the result of basal state and the results of the controlled respiration increasing continuously through the controlled respiration. Conclusion: We had examined the effects of controlled respirations on cardiovascular system in multiple points of view. The effects of controlled respirations on cardiovascular system can't be explained in a simple way, as the cardiovascular system is controlled by many factors. Therefore, more physiological parameters must be measured in the future study on the effect of the controlled respiration on human cardiovascular system.

• Journal of Biomedical Engineering Research
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• v.38 no.3
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• pp.95-101
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• 2017

In this study, photoplethysmography(PPG) was suggested as a way to replace the ankle-brachial index(ABI) in diagnosing PAD. The method using the PPG was presented for the simplification of the PAD diagnosis method which was used before. And the index related to the health condition of the artery from the PPG measured in both big toes of the subjects through the experiment was drawn. The indexes showing the significant relativeness in the Pearson correlation analysis with the ABI were the stiffness index(SI), reflection index(RI); it was confirmed each of them had the correlation coefficient of 0.688, and 0.637 at p < 0.05. The explanation ability of the linear regression equation derived using ABI, SI and RI was 52.5%. The explanation ability of the secondary curve regression equation derived using ABI, squared SI was 54.7%. It is expected to provide patients with significant results and draw the index associated with PAD by measuring PPG easily in the real life instead of the ambulatory care field.

• Journal of the Korea Society of Computer and Information
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• v.28 no.11
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• pp.155-160
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• 2023

This paper presents a method for predicting blood pressure using the photoplethysmography signals. First, after measuring the optical blood flow signal, artifacts are removed through a preprocessing process, and a signal for learning is obtained. In addition, weight and height, which affect blood pressure, are measured as additional information. Next, a system is built to estimate systolic and diastolic blood pressure by learning the photoplethysmography signals, height, and weight as input variables through an artificial intelligence algorithm. The constructed system predicts the systolic and diastolic blood pressures using the inputs. The proposed method can continuously predict blood pressure in real time by receiving photoplethysmography signals that reflect the state of the heart and blood vessels, and the height and weight of the subject in an unconstrained method. In order to confirm the usefulness of the artificial intelligence-based blood pressure prediction system presented in this study, the usefulness of the results is verified by comparing the measured blood pressure with the predicted blood pressure.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.10
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• pp.598-605
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• 2003

In this paper, we propose the method that separates PPG signal and motion artifact signal from two input signals using new independent component analysis algorithm in time domain. In order to eliminate the large level artifact efficiently, block interleaving. lowpass time filtering and innovation processing technique were applied in ICA preprocessing, and FastICA algorithm were applicable. Experiments are made with the numerical simulation and the real PPG signal including four kinds of motion artifact pattern. Our results show that ICA can effectively detect, separate and remove motion artifact in input signals. Then from the separated signals we restore the original PPG signal and propose a new method which computes SpO$_2$ using ICA mixing matrix.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.225-226
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• 2012

본 논문에서는 손목과 손가락에서의 광전용적맥파(photoplethysmography:PPG)를 이용한 맥파 동시 측정에 있어서 두 신호의 peak간의 시간차와 혈압과의 관계를 비교하였다. 이를 통하여 연속적인 혈압측정방법에 대해 측정 가능성을 발견하였다. 본 논문에서는 적외선을 이용한 반사형 PPG 측정 시스템을 사용하였으며 손목과 손가락에서 동시에 측정한 신호를 측정된 혈압과 비교하였다. 이를 통하여 혈압에 따라 손목과 손가락의 PPG신호 peak간의 시간차에 일정한 변화가 있음을 발견하였고 이를 통하여 손목과 손가락사이의 PPG 신호만으로 연속혈압측정이 가능하다는 결론을 얻었다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.07a
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• pp.353-354
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• 2013

본 논문에서는 기존의 손에서 측정하는 PPG를 발가락에서 측정하여 지속적인 무자각적 측정이 가능함을 제안한다. 발가락에서의 측정은 손이 자유로워져 일상 업무에 영향을 끼치지 않으면서 고정하기 유용하기 때문에 보다 상황에 맞는 정확한 파형 검출이 가능하다. 따라서 본 논문에서는 발가락에서의 측정 가능성을 확인한 후 소형 device 제작 및 실험을 통해 손과 발에서 PPG를 측정, 비교하여 발가락에서도 PPG 파형 검출이 가능함을 보인다.

• Journal of Sensor Science and Technology
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• v.13 no.5
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• pp.383-391
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• 2004

In this study, we implemented the pulse transit time (PTT) system to examine usefulness of the monitoring method of distensibility and elasticity using photoplethysmography sensor in vivo. PTT is defined as the time interval between the peak of QRS complex in ECG signal and the maximum slope point of photoplethysmography. these two signals were converted to digital data by means of AID converter, then PTT was evaluated by heartbeat using PC. Results of analysis were displayed as a graph using spline interpolation method. The variance of PTT was measured repetitiously to verify efficiency of PTT system in resting state and hyperemic state. Repeated measurement of PTT was not same value but showed that coefficients of correlation were related with each other as 0.8302 (P<0.01) in resting state. And also repeated measurement of PTT showed significant correlation as 0.868 (P<0.01) in the hyperemic state. These result showed that PTT is reflect on transient pressure variance in the artery and is very useful method for the evaluation of prognosis of the hypertension and arteriosclerosis.

• Journal of Biomedical Engineering Research
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• v.31 no.4
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• pp.328-334
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• 2010

Over the past few years, a considerable number of methods have been proposed and applied for the classification of photoplethysmography (PPG). Most of the previous studies, however, focused on the qualitative description of the pulse type according to specific disease and thus provided ambiguous criteria to interpreters. In order to screen out this problem, we present a quantitative method for the pulse type classification including the second derivative of photoplethysmography (SDPTG). In the PPG signal, we have classified the signal as 4 types using the position and the presence of the dicrotic wave. In addition, we have categorized the SDPTG signal as 7 types using the position and the presence of "c" and "d" wave and the sign of "c" wave. In order to check the efficacy of the proposed pulse type classification rule, we collected pulse signals from 155 subjects with different ages and sex. From the correlation analysis, Class 1(p<0.01) and Class 2(p<0.01) in the PPG signal are significantly correlated with ages. In a similar manner Class A(p<0.01), Class C(p<0.05), Class D(p<0.01), and Class F(p<0.01) in the SDPTG signal are considerably correlated with the ages. From these observations, and some earlier ones [4], [5], we can conclude that since the newly proposed method has objectivity and clarity in pulse type classification, this method can be used as an alternative of previous classification rules including similar age-related characteristics.