## 2 Materials and Methods
### Destruction Removal Efficiency (DRE)
#### 2.2.4 Validation of Improved Measurement  
To confirm the validity of the improved measurement method, linearity, accuracy, precision, and verification and quantification limits were analyzed using CHF\({}_{3}\) and C\({}_{2}\)F\({}_{6}\). At first, to confirm linearity, measurements of 5-point concentration ranges (20, 40, 60, 80, and 100 ppm) of CHF\({}_{3}\) and C\({}_{2}\)F\({}_{6}\) were taken using certified reference material (CRM) of 100 ppm N\({}_{2}\) balance. As a result, the correlation coefficient (R\({}^{2}\)) values of CHF\({}_{3}\) and C\({}_{2}\)F\({}_{6}\) confirmed that R\({}^{2}\) values exceeded 99% or more (Figure 4). \begin{table}
\begin{tabular}{c c} \hline
**He Gas Concentration (\%)** & **Error Rate (\%)** \\ \hline
67.46 & 28.62 \\
58.02 & 36.92 \\
47.95 & 45.78 \\
37.20 & 55.24 \\
25.68 & 65.37 \\
13.31 & 76.24 \\ \hline \end{tabular}
\end{table} 
Table 6: Injected He gas concentration variations and their corresponding error rates. Figure 3: Error rate graph for comparing injected He concentration variations. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**N\({}_{2}\)**} & \multirow{2}{*}{**STD Gas**} & \multicolumn{2}{c}{**Pre-Set Kr**} & \multirow{2}{*}{**Measured Kr**} & \multirow{2}{*}{**Gas Factor**} & \multirow{2}{*}{**Temperature and**} & \multirow{2}{*}{**Volume Flow**} & \multirow{2}{*}{**Calculated True**} & \multirow{2}{*}{**Error Rate (\%)**} \\  & & **Concentration (\%)** & & & & & **Rate (SLM)** & & **Flow Rate** \\ \hline
7 & 3 & 0.6 & 0.613 & 1.382 & 1.073 & 241.612 & 247.2 & 2.26 \\
5 & 5 & 1.0 & 1.01 & 1.382 & 1.073 & 146.493 & 148.3 & 1.23 \\
3 & 7 & 1.4 & 1.410 & 1.382 & 1.073 & 105.166 & 105.9 & 0.74 \\ \hline \end{tabular}
\end{table} 
Table 5: Arithmetic error rate values compared true values in Experiment 2. Then, to confirm accuracy, the standard material of the median concentration for each item was analyzed four times using a CRM, and the average measurement value was divided by the median concentration value to obtain the results. This analysis was repeated 5 times with 60 ppm, which is the median concentration of CRM (100 ppm) from CHF3 and C2F6. Then, the average repeated analysis values were divided by the median concentration values (60 ppm) and calculated as a percentage. As a result, the accuracy values of CHF3 and C2F6 were calculated as 100.09 and 99.89%, respectively, showing that the accuracy of CHF3 and C2F6 was estimated within a validity range of 90-110%. To confirm precision, repeatability and reproducibility were verified. Repeatability was determined by analyzing the standard material of the median concentration for each item 4 times using a standard gas, and calculating the relative standard deviation (RSD). In order to confirm the repeatability, the analysis was repeated 5 times with 60 ppm, which is the median concentration of CRM (100 ppm) of CHF3 and C2F6, and the RSD of analysis values were estimated. As a result, the RSDs of CHF3 and C2F6 were calculated as 0.07 and 0.03%, and the values were confirmed to be within a validity range of 5%. Reproducibility was calculated over a 5-point concentration range using the CRM (100 ppm) of CHF3 and C2F6 by measuring four or more analyses from the testing laboratory and by performing analysis at different times. As a result, the accuracy measured to check the reproducibility of CHF3 and C2F6 was analyzed within the validity range of 90 to 110%. Furthermore, the detection limit was analyzed based on a 500 cm gas cell. The detection limit was calculated by repeatedly measuring the concentration (that is twice that of the manufacturer's provided detection limit) 7 times, and then multiplying the standard deviation by 3.14 to calculate the expanded uncertainty. The measurement equipment's detection limits of CHF3 and C2F6 provided by the manufacturer were 1.5 and 0.5 ppm, and were calculated by multiplying the standard deviation of the values (3.14) measured 7 times at 3 ppm and 1 ppm, which are double the concentration values.