Hang-Sik Shin

Principal Point Discrimination of Electrocardiogram for Automatic Diagnosis

Electrocardiogram provides critical information about the cardiovascular system. For diagnosis, medical doctors consider the duration, slope and peak amplitude between principal points of an electrocardiogram. Therefore, as a first step, it is very important to find essential points of an electrocardiogram - P, Q, R, S, and T. In this paper, we propose a simple PQRST detection algorithm based on peak-detection and timing analysis, and also we use 8 MIT-BIH databases that have definite R-peak for algorithm testing. In normal cases, the proposed algorithm worked with high accuracy. However, the proposed algorithm has propagation error because of its in order characteristic.

Analysis of Arterial Stiffness Variation by Photoplethysmographic DC Component

Assuming that photons absorbed by a vessel do not have acute variations, DC component reflect the basal blood volume (or diameter) before blood pulsation. Vascular stiffness and reflection is influenced by changes in basal blood volume (or diameter). This paper describes analysis of the characteristic variations of vascular stiffness, according to relative variations in DC components of the PPG signal (25-75%). For quantitative analysis, we have used parameters that were proposed previously, reflection and stiffness index, and the second derivative of PPG waveform, b/a and d/a. Significantly, the vascular stiffness and reflections were increased according to increase in DC component of the PPG signal for more than about 3% of baseline values. The systolic blood pressure were increased from to mmHg, about 2.76% (r

Reconstruction of the Undersampled Photoplethysmogram with Various Interpolation Methods

The purpose of this research is to investigate the effect of sampling frequency on the photoplethysmography (PPG) and to evaluate the performance of interpolation methods for under-sampled PPG. We generated down-sampled PPG using 10 kHz-sampled PPG then evaluated waveshape changes with correlation coefficient. Correlation coefficient was significantly decreased at 50 Hz or below sampling frequency. We interpolated the down-sampled PPG using four interpolation method–linear, nearest, cubic spline and piecewise cubic Hermitt interpolation polynomial – then evaluated interpolation performance. As a result, it was shown that PPG waveform that was sampled over 20 Hz could be reconstructed by interpolation. Among interpolation methods, cubic spline interpolation showed the highest performance. However, every interpolation method has no or less effect on 5 Hz sampled PPG.

Low complexity and power consumption design for pacemaker using shared MAC structure based on FPGA platform

Most of the critical issues of cardiac pacemakers and ICDs are the device size and power consumption problem. Because devices size for cardiac implant is limited, we always have to consider trade-off relationship between size and longevity. Accordingly, we proposed a MAC-sharing structure based on FPGA platform for small size and low power consumption. The MAC-sharing structure contains a single multiplier using a time division method, hence we reduce a system complexity and power consumption with this method. In this paper, we show the result of atrial fibrillation detection using the proposed structure based on a FPGA platform.

Development of System for measuring Nerve-Conduction Velocity

As a method of observing regeneration of damaged nerves, research is being conducted on analyzing the electric signals of nerve fibers that regenerate damaged nerves by implanting a microelectrode array between those nerves[1,3]. There are methods that evaluated for regerated nerves, such as electrophysiology test(nerve conduction velocity, morphology, maximum amplitude), function analysis(i.e gait analysis for sciatic nerves), and histological test. For electrophysiology test, there are needed exactly spike detection(positive phase and negative phase). ENG’s bandwidth has the broader than other biomedical signals. Therefore, procedure of biomedical signal processing requested many computation quantities. In this paper, we proposed the simplified system for conduction velocity regenerated nerve, based on MEA, without signal processing complexity.