Wan-taek Han

Feature extraction for heart sound recognition based on time-frequency analysis

Heart sounds provide clinicians with valuable diagnostic and prognostic information. Although heart sound analysis by auscultation is convenient as a clinical tool, heart sound signals are so complex and nonstationary that they are very difficult to analyze in the time or frequency domain. We have studied the extraction of features in the time-frequency (TF) domain for recognition of heart sounds through TF analysis, such as short time Fourier transform (STFT), Wigner distribution (WD), and wavelet transform (WT). After these transformations, we normalized the heart sound in the TF domain and compared a normal heart sound with an abnormal one to verify the clinical usefulness of our extraction methods for heart sound recognition.

WHAM: A novel, wearable heart activity monitor based on Laplacian potential mapping

In this paper, a novel, wearable cardiac monitor (hereafter called WHAM) is proposed which allows a continuous and real-time monitoring of users cardiac conditions. The proposed device is composed of 3 main components: a disposable electrode, a controller, and personal gateway (e.g., cellular phone, PDA, and smart phone etc.). The ECG signal is recorded according to the surface Laplacian of the body surface potential. We investigated the feasibility of WHAM as a wearable ambulatory device for continuously and on-line monitoring a users cardiac conditions. To this end, the ECG signals recorded with WHAM were compared with those obtained by Wilsons unipolar chest leads, that is, v1 to v6. As a result, the ECG signals recorded with WHAM showed the similar morphology to Wilsons unipolar chest leads (v1 to v6) with the exception of P and T waves, although there is a difference between amplitudes of both signals. Also, it is shown that the R-peaks are accurately detected by the algorithm at the accuracy of more than 99% for the ECG signals of WHAM recorded during resting and walking. From these results, it is found that the WHAM shows enough feasibility and has advantages as a wearable ambulatory monitoring device in that the hardware is miniaturized enough small to integrate on a small region, thereby no wire leads need

Microwave propagation on acupuncture channels.

Quantitative studies on functional state of acupuncture points and meridians have been done mostly by electrical measurement that requires the contact of the electrode on skin and is subject to pressure, humidity, etc. In this study, a new modality of using microwave was investigated. Microwave energy in the frequency range of 250 approximately 550MHz was irradiated on an acupuncture point. Transmitted microwave energy along the meridian was measured at the next acupuncture point of the same meridian. Diabetic and cancer patients were compared with healthy persons. Normal group consisted of 50 healthy persons. Diabetic group included 50 diabetic patients. Breast cancer group had also 50 patients. All 12 meridians on both right and left hands and feet were measured. For the diabetic group, the microwave energy propagation in this frequency range was 1.417 dB lower along Lung channel and 1.601 dB higher along Spleen channel compared with the normal group regardless of sex and diabetic types. For cancer patients, the propagation was 1.620 dB lower along Liver channel and 1.245 dB higher along Kidney channel compared with the normal group. Microwave energy proved to be a potential diagnostic method.