| Summary: | 碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程所 === 92 === Suspension particulates (PM10) are the major pollutants in Taiwan. Nowadays, although the PM 10 has decreased for the last several years, but it is still the key substance for PSI index. The traditional measurement methods for PM10 have been updated and replace by modern auto-instruments. A new instrument by applying the light scattering characteristics, and the information technology has reached an auto-measurement function, which becomes more efficient and man power saving. There are several advantages of auto-optical device for dust measurement. The response time is shorter (6 seconds only) than the traditional instrument, the measurement items are plentiful (PM10, PM2.5, PM0.1 are measure at the same time) than the conventional instrument. Besides to considering the device function, moreover to justify the accuracy, precision and identity of the new instrument, the correction and correlation with the existing system should be conducted. The final goal is to achieve the consistent and reliable data, which can represent the actual circumstance as the traditional instrument had been shown.
This study is aiming at different measurement principles and restriction for measuring the dust concentration. Through the paper survey, Metone BAM 1020 (b-Ray decadence method) was chosen as the reference device, and Grimm 1.107 (Light Scattering Method) as the comparison device. These two devices were installed at the dust monitoring station, Ai-Kuo and Cheng-Kung station, where were operated by Kaohsiung City EPA. Three parallel experiments following the experimental design had been conducted from May to August of year 2003. The different environmental conditions had been studied, such as the day time and night time, moisture levels, PM10 concentration and etc., the responded group data had been analyzed by mean value, variance check, correlation and ratio contract analysis. The followings are the summary of statistic analysis results for the study.
The correlation analysis shows these two devices have middle to high relationship for each experiment. The results show the relationship in day time is higher than night time; low moisture is higher than high moisture. The cross analysis show the relationship in low moisture level of day time is higher than low moisture level of night time; and high moisture level of day time is higher than high moisture level of night time. Analysis by combining all the data show the correlation index increased and tend forward to coincide with each other.
Under the reliable value a=0.5, and the reliable interval of 95%, the group data mean value and variance check (T-test) show obvious different for these two devices. The data from reference device (Metone BAM 1020) seemed to be lower than the comparison device (Grimm 1.107). Use the data of Grimm 1.107 as A and Metone BAM 1020 as B, the mean value of (A/B) ratio data is 0.74 and standard deviation is 0.14. 68% of all (A/B) ratio data located within 0.88 to 0.60 (0.74±0.14), the max value of all (A/B) ratio data is 1.17 and the min value is 0.36.
The mean value of ratio contract under high, middle and low dust concentration reveals higher than the other simulated condition. The other simulated condition show the ratio contract values are very close or uniform. The ratio average of day time is higher than night time, and low moisture level is higher than the night time. Besides, the standard deviations are different under different conditional comparison. This study concluded these two devices “cannot say to be the same”. The difference may due to the different measurement mechanism, or the sensitivity difference to the temperature and moisture. Analyses by combining all the data show the difference become smaller and tend to coincide. But it still shows the ratio average of day time is higher than night time, and low moisture level is higher than the night time. Comparing the mean value and standard deviation under low, middle and high dust concentration, there is no trend or tendency appeared.
This study concludes that more data show better correlation, tendency trend, and even better T-Check value. This experiment only conducted in summer time, there is no data for different season and different parameters and levels. Owing to the limited number of devices and duration time, it is not yet clarifying the full fit of the Grimm 1.107 to Metone BAM 1020. We suggest that in order to get a convincible result and reliable reference for future user of such optical device for dust measurement, it is necessary to perform a longer time comparison and function check.
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