In Cheol Jeong

A New Method to estimate Arterial Blood Pressure using Photoplethysmographic Signal

Preceding studies have shown photoplethysmographic (PPG) signal resembles blood pressure (BP) wave and varies. Some investigators also have studied this relationship to explain complex hemodynamic characterization. The purpose of this study is to make a trial of finding arterial BP (ABP) using PPG signal. This new attempt is based on the theory that BP consists of the change of blood volume (BY) and the resistance of vessels. This study proposes a method to estimate BP from PPG signal and points to be considered when we use this method. Therefore we can classify cardiac output (CO) and the blood vessel resistance (VR) by analyzing PPG signal. Signals were obtained from the tails of three healthy dogs and the fingers of six patients who have changes of BP. In the animal test, we first found the correlations between PPG signal and BP, and then we could reconfirm the relationship in the clinical test. PPG signal could be influenced by the pressure (P) that occurred between the index finger and the sensor and the temperature (T) of the interest region, so we examined these influences with six healthy subjects. From the experimental results, we suggest the relationship of the estimation of BP from PPG signal. When PPG signal is normalized by P and T, this PPG signal offers more accurate estimation of BP. This study could be able to provide a new BP measurement system that has not only convenience but also accuracy

Development of Bio Signal Measurement System for Vehicles

This study intends to research and develop unrestricted measuring system and user interface in a new form to effectively collect individual bio information of car users - driver and passenger - with the systems previously researched and developed as basic platform. The whole system is designed to measure bio signals for monitoring the physiological changes in the vehicle. For system evaluation, an actual operating condition was offered by mounting and equipping the system in an actual vehicle, and then the measured information was analyzed and verified. Through these processes, the measured signals were evaluated and its availability in the vehicle was confirmed. In this study, the system to induce drivers to safe driving was developed through consecutive monitoring of fatigue and increased risk of safety accident as drivers drive for many hours. In addition, health care service system for driver and passenger was developed through the measurement of various bio signals. Besides, a case of unrestricted and unconscious bio signal measurement system was suggested with completely recognizing and understanding a special condition of driving.

Development and evaluation of an improved technique for pulmonary function testing using electrical impedance pneumography intended for the diagnosis of chronic obstructive pulmonary disease patients.

Spirometry is regarded as the only effective method for detecting pulmonary function test (PFT) indices. In this study, a novel impedance pulmonary function measurement system (IPFS) is developed for directly assessing PFT indices. IPFS can obtain high resolution values and remove motion artifacts through real-time base impedance feedback. Feedback enables the detection of PFT indices using only both hands for convenience. IPFS showed no differences in the sitting, supine, and standing postures during the measurements, indicating that patient posture has no effect on IPFS. Mean distance analysis showed good agreement between the volume and flow signal of IPFS (p < 0.05). PFT indices were detected in subjects to differentiate a chronic obstructive pulmonary disease (COPD) patient group from a normal group. The forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1/FVC, and peak expiratory flow (PEF) in the COPD group were lower than those in the normal group by IPFS (p < 0.05). IPFS is therefore suitable for evaluating pulmonary function in normal and COPD patients. Moreover, IPFS could be useful for periodic monitoring of existing patients diagnosed with obstructive lung disease.

Electrocardiogram signal processing method for exact Heart Rate detection in physical activity monitoring system: Wavelet approach

Physical Activity Monitoring is a device that can measure the human activity quantity quantitatively through Heart Rate detection in real time. R-Spike detection of ECG is required for this Heart Rate detection. Since Physical Activity Monitoring System is usually used during activity or exercise, however, signal measured in ECG System is contaminated by diverse noises. Diverse noises become the factors of failure in R-Spike detection. Such factors impede the exact HR detection. This paper suggests method to convolute wavelet function and scaling function as the optimum signal disposition method for optimum R-Spike detection. This method was compared with the R-Spike detection method that uses quadratic spline wavelet presented before. To verify performance of signal disposition method suggested in this paper, the ECG of noise stress test database (NSTDB) and MIT-Database were tested in combination. Then, the sensitivity of R-Spike detection rate for noise was also additionally tested by gradually lowering SNR of NSTDB. Then, it was verified through ECG signal that was actually measured in physical activity monitoring.

A Study on Compensation of Error Rate in Noninvasive Blood Pressure Measurement System using Tactile Sensor

The purpose of this paper is to use tactile sensor to compensate the error rate. Most automated sphygmomanometers use oscillometric method and characteristic ratio to estimate systolic and diastolic blood pressure. However, from the face that maximum amplitude of oscillometric waveform and characteristic ratio are affected by compliance of aorta and large arteries, a method to measure the stiffness of arteries by using tactile sensor was chosen in order to integrate it with sphygmomanometer in the future instead of using photoplethysmography. Since tactile sensor is very weak in movements, efforts were made to maintain subject’s arm fixed, and 40Hz low pass filter was used to eliminate noise from power source and high frequency noise. Analyzing program was made to get time delay between first and second peak of averaged digital volume pulse(ΔTDVP), and subject’s height was divided by ΔTDVP to calculate stiffness index of arteries(SIDVP). Regression equations of systolic and diastolic pressure using SIDVP and mean arterial pressure(MAP) were computed from the training set(23 subjects) among total 46 subjects(age: 26.80±3.12, male: female = 32: 14) and were tested in 61 subjects to compensate error rate. Error rate in total subjects were systolic 6.51±9.25mmHg, diastolic 3.83±11.67mmHg, and those in the test setv were −5.50±9.27mmHg and 4.34±10.80mmHg each. Consequently, error rates were compensated especially in diastolic pressure using SIDVP, various slopes from digital volume pulse and MAP to systolic 2.57±8.05mmHg and diastolic 2.08±8.75mmHg.

Development of sports health care system suitable to the fitness club environment

This paper presents a sports health care system suitable to the fitness club environment. As improvement of quality of life, increasing interest of exercise, it has been studied and developed products briskly for exercise management. As such products are developed mainly for outdoors activity, however, it has a limitation to systematically manage exercise in consideration of fitness club environment. We want to overcome this limitation through by development of systematically exercise management system using interacting interface network. We devised system suitable to control and monitor systematic exercise using bio-module available for real-time bio-signal processing based on a novel algorithm that could reduce operation complexity when users do exercise in the fitness club environment. The overall system is composed of bio-module that can collect bio-signal information and analyze signal in real time, exercise equipment control module and exercise management server. Based on bio-signal information processed in real time, it is possible for exercise management prescription in real time according to users health condition using organically interacting communication. We expect that our suggested system contribute to propagation and development of sports health care field.

A preliminary study on autonomic nervous system assessment during aerobic exercise using TEMPV

The purpose of this study is to monitor the autonomic nervous system with average skin temperature and its variability, of which both are compared with heart rate variability. Six healthy male college students participated in a test which is composed of rest for 5 min., exercise for 20 min. and recovery for 10 min. to measure their ECG and skin temperature with BIOPACK. The test found similarity between HRVs total power and peak amplitude of skin temperature variability towards physical stress. Furthermore, the constant fall of mean temperature during exercise and recovery capacity during recovery stage also proved that subjects differ in their autonomic nervous system activities to maintain homeostasis.

New Algorithms for compensation of Error Rate in Noninvasive Blood Pressure Measurement System Using Optical Sensors

The purpose of this study is to compensate the error rate using optical sensors. Most automated sphygmoma-nometers use the oscillometric method and the characteristic ratio to estimate systolic and diastolic blood pressure. This paper describes new algorithms for non-invasive blood pressure measurement based on the shape of intra-arterial plethysmograph. We made the plethysmograph characteristic ratio algorithm (PCRA) that could estimate mean arterial pressure (MAP) and the extinctive plethysmograph algorithm (EPA) that could estimate systolic arterial pressure (SAP). With these new algorithms we advanced a new blood pressure measurement system and evaluated these algorithms with 15 subjects (age: 26 to 72 (48.53±11.75), male: female = 8: 7). The SAP, MAP and diastolic arterial pressure (DAP) range were each from 119 to 156mmHg, from 89 to 113mmHg and from 70 to 96 mmHg. The pressure values were obtained with an automated sphygmomanometer and our algorithms, and then we compared these values with second reference blood pressure measurement (European Society of Hypertension International Protocol in adults). Regression equations of systolic and diastolic pressure using new algorithms were computed from training set (8 subjects) and were tested in 7 subjects to compensate error rate. Error rate in total subjects were systolic 5.53±5.25mmHg, diastolic 7.87±6.51mmHg, and those in test set were 4.50±5.04mmHg and 7.88±7.72mmHg each. In conclusion, error rates were compensated SAP and DAP using PCRA and EPA to systolic 0.71±3.45mmHg and diastolic 1.71±3.90mmHg. Therefore we discovered fairly good algorithms able to compensate and provide models able to be more corrective noninvasive blood pressure measurement system.