STUDY OF THE DEVELOPMENT AND CALIBRATION OF A PARTICULATE MATTERS MEASUREMENT DEVICE WITH WIRELESS SENSOR NETWORK FUNCTION

초록

A Zigbee-based Ubiquitous Sensor Network (USN) is broadly used in many industrial applications to provide flexible measuring environments. In particular, the USN system substitutes existing measuring devices under harsh environments such as measuring the levels of air pollutants in subway stations. In order to monitor the particulate matter (PM) levels in subway tunnels, this research utilizes the USN technique. A new wireless sensor module, PMX, has been designed and manufactured to sense PM10 and PM2.5 simultaneously. Measurements has been conducted at subway tunnel in Seoul. The effects of the Zigbee-based communication protocols have been verified. The effects and PM level have been measured, analyzed and compared with those from existing commercial PM measurement device, the Dust spectrometer, in sensing the PM10, PM2.5 levels of the selected subway tunnel. The test result indicates that the two systems showed a similar time series trend while the measured values were somewhat different. A simple correlation analysis of the two groups of data showed the coefficient of determination of 0.7 for PM10 and 0.9 for PM2.5. In the case of PMX data, most data were concentrated around the trend curve. Therefore, the calibration of PMX data was needed to apply it in the field. For the calibration, statistical processes of simple linear regression and nonlinear regression were selected. The result showed that the correlation coefficient of simple linear regression was 0.7 for PM10 and 0.9 for PM2.5 while that of nonlinear regression was 0.8 for PM10 and 0.9 for PM2.5, indicating the nonlinear regression showed higher correlation coefficient. Therefore, it was determined that nonlinear regression was a better method to calibrate the system developed for this study.