Jong Pal Kim

Estimation of Activity Energy Expenditure: Accelerometer Approach

A novel algorithm estimating the calorie expenditure during physical activities is introduced. The physical activity is quantified by the integration of the accelerometer signals obtained from the 3D accelerometer fixed at the waist level of the human body. Simultaneous measurements of activity and calorie expenditure using 3D accelerometer and gas analyzer show the activity calorie expenditure increases as the activity increases with different rates depending on the type of activities (e.g., walking, running) as well as the physical characteristics of the subjects (e.g., gender, age, mass, and height). Based on the experimental data gathered from 94 subjects, we suggest a new algorithm estimating the activity calorie expenditure dependent on the demographic data of the subjects and the types of the activity

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

Factors affecting the accuracy of volume-oscillometric blood pressure measurement during partial pressurization of the wrist

We compared the volume-oscillometric responses of the airbag pressure sensor and the contact force sensor across and along the radial artery on the wrist during partial pressurization by an airbag. Because of the anatomic structure and non-uniform pressurization pressure distribution, elongated and shifted oscillometric pressure waveform envelope variations are observed. For the contact force sensors directly above the radial artery, S-shaped pressurization curves can be seen possibly due to temporal softening of the radial artery stiffness at near zero transmural pressure. These differences in the shape of oscillometric envelope as well as pressurization curve may be the leading factors for inaccuracies of volume-oscillometric blood pressure measurement by partial pressurization method using an airbag.

The preliminary study on the clinical application of the WHAM (Wearable Heart Activity Monitor)

In this paper, we investigated the validity of the WHAM (wearable heart activity monitor) in the clinical applications, which has been implemented as a wearable ambulatory device for continuously and long-term monitoring users cardiac conditions. To this end, using the WHAM and the conventional Holter monitor the ECG signals over 24 hours were recorded during daily activities. The signal from the WHAM was compared with that from the conventional Holter monitor in terms of the readability of the signal, the quality of the signal, and the accuracy of arrhythmia detection. The performance of the WHAM was a little lower as compared with the conventional Holter monitor, although showing no significant difference (the readability of the signal: 97.2% vs 99.3%; the quality of the signal: 0.97 vs 0.98; the accuracy of arrhythmia detection: 96.2% vs 98.1%). From these results, it is likely that the WHAM shows the performance enough to be used in the clinical application as a wearable ambulatory monitoring device

Effect of pressurization methods on the accuracy of wrist blood pressure measurement

In developing a wrist blood pressure monitor of high and reliable accuracy, the effect of different pressurization methods on the accuracy of blood pressure measurement at the wrist using oscillometry is investigated in this paper. 30 volunteers are recruited and blood pressure readings are taken with three different methods of pressurizing the wrist. It was found that measurement of mean arterial pressure (MAP) is more accurate when the wrist is locally compressed directly over the radial artery (−2.6 ± 11.4 mmHg) or with a region of surrounding tissue (10.3 ± 6.0 mmHg) than when the whole wrist is compressed by a conventional, constricting cuff (−11.4 ± 16.4 mmHg). Characteristics of accuracy, however, differ between the two local pressurization methods. While a square airbag that compresses the wrist directly over the radial artery may measure the most accurate MAP on average, the range of errors among individuals is large. Contrarily, measurements taken by pressurizing a region over the radial artery with a bladder are least affected by individual variability. In order to measure blood pressure accurately at the wrist while unbiased by the population-based algorithmic compensation to ensure accuracy among different individuals, therefore, the use of local pressurization method may be the most appropriate.