## 3 Results and Discussion  
The individual one-way shipments to five destinations were analyzed to calculate the drop heights, number of drops, and impact orientations. Table 2 shows the 90 th, 95 th, 99 th percentile, average, and maximum number of drops as a function of the different package sizes and weights in the current study. It also compares the current study's results with past studies conducted in Europe [12] and the USA [16], and to the ISTA 3A testing standard [22]. Figure 4 visually presents CDF plots of the number of drops found during this study. The results showed a small, but not statistically significant, difference in the number of impacts between the medium and small boxes: less than or equal to eight shock events occur for 95% of medium package shipments, and less than or equal to seven shock events occur for 95% of small box shipments. The CDFs of the number of drops for small and medium packages were compared using the two-sample Kolmogorov-Smirnov (KS) test with a significance level of 95%. The obtained \(p\)-value of 0.76 suggests that there isno significant difference between the CDFs of the number of drops for small and medium packages at the chosen significance level. The computed D statistic of 0.17 indicates the maximum absolute difference between two CDFs. These findings confirm that there is no strong statistical evidence to support a significant difference between the cumulative distributions of the number of drops for the small and medium boxes. These results did not follow what a previous study had found: heavier packages usually experience less harsh handling [13]. This may have been because the difference in the weight and size of the tested small and medium decoys was not big enough for the Korean parcel delivery system to cause disparity in the number of drops. Furthermore, the number of drops observed in the Korean parcel delivery environment was significantly lower than the similar studies conducted in Europe [12] and the USA [16,17], and the ISTA 3A testing standard [22] (Table 2). This seems to be due to fewer handling points in Korea than in countries with larger territories. Packages in Korea mostly go through only one hub terminal and one sub terminal during any trip. In contrast, packages in Europe and in the US.A have a higher chance of going through more handling points, such as multiple hub and sub terminals, before they reach customers. Figure 4b presents the CDF for the calculated EFFDH based on the overall dataset, while Table 3 shows the 90 th, 95 th, 99 th percentile, and maximum EFFDH as a function of the different package sizes and weights in the current study. These results showed no significant difference between the medium and small boxes based on the two-sample Kolmogorov-Smirnov test (\(p\) value = 0.14, D = 0.15). This confirms that the two investigated package sizes and weights are not treated differently or separately during handling in the Korean \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{8}{c}{**Number of Shocks/Impacts**} \\ \hline
**Percentile** & **Medium + Small** & **Medium Box** & **Small Box** & **Europe [12]** & **USA [16]** & **USA [17]** & **USA [17]** & **ISTA 3A [22]** \\ \hline
90 th & 6.16 \(\approx\) 7 & 6.44 \(\approx\) 7 & 5.81 \(\approx\) 6 & 16 & - & - & \\
95 th & 6.85 \(\approx\) 7 & 7.11 \(\approx\) 8 & 6.50 \(\approx\) 7 & 17 & - & - & 17 \\
99 th & 8.17 \(\approx\) 9 & 8.37 \(\approx\) 9 & 7.81 \(\approx\) 8 & 19 & - & - & \\ Maximum & 9 & 9 & 8 & 21 & 74 & 184 & \\ \hline \hline \end{tabular} Note: Highest numbers from the literature are listed in this table.  
\end{table} 
Table 2: Shock/impact frequency observed depending on the package size and weight, reported in the previous study, and ISTA 3A standard. Figure 4: CDF plot of the (**a**) number of drops and (**b**) the calculated equivalent free-fall drop height (EFDH) for the overall dataset as a function of package size and weight.