• Journal of Korean Society for Atmospheric Environment
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• v.33 no.5
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• pp.515-520
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• 2017

$PM_{2.5}$ concentrations were measured using a cyclone, impactor (the U.S. Environmental Protection Agency well impactor ninety-six, WINS) and optical particle counter (OPC) at a campus site located in Yongin for the period August 2014 through March 2017. The concentrations from cyclone (Y) were generally higher than those from impactor(X); the best-fit line was Y=1.22X+5.64. The ratios of $PM_{2.5}/PM_{10}$ ranged from 0.61 to 0.66 when $PM_{2.5}$ concentrations from cyclones in selected studies were converted into those from impactors using a regression equation in this study. The slope of the best-fit line between OPC and impactor was close to 1 at 0.95, while that between OPC and cyclone was 0.72. After sampling, the flow rate in the low-volume air sampler with cyclone decreased by 3% on average, which did not have a significant effect on measured concentrations.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.2
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• pp.157-163
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• 2015

To establish National Reference Method (NRM) for $PM_{2.5}$, operational performance of 5 different commercial gravimetric-based $PM_{2.5}$ measuring instruments was assessed at Bulkwang monitoring station from January 23, 2014 to February 28, 2014. First, physical properties, design, and functional performance of the instruments were assessed. Evaluation was carried out to determine whether operating method for the instruments and levels of QA/QC activities meet the data quality objectives (DQOs). To verify whether DQOs were satisfied, reproducibility of QA/QC procedures, accuracy, relative sensitivity, limit of detection, margin of error, and coefficient of determination of the instruments were also evaluated. Results of flow rate measurement of 15 candidate instruments indicated that all the instruments met performance criteria with accuracy deviation of 4.0% and reproducibility of 0.6%. Comparison of final $PM_{2.5}$ mass concentrations showed that the coefficient of determination ($R^2$) values were greater than or equal to 0.9995, and concentration gradient ranged from 0.97 to 1.03. All the instruments satisfied criteria for NRM with the estimated precision of 1.47~2.60%, accuracy of -1.90~3.00%, and absolute accuracy of 1.02~3.12%. This study found that one particular type of measuring instrument was proved to be excellent, with overall evaluation criteria satisfied.