## 3 Results and Discussion
Medium + small indicates a combination of data obtained from both medium- and small-sized boxes, medium indicates data obtained from medium-sized boxes, and small indicates data obtained from small-sized boxes. parcel delivery environment. The max EFFDH in Korea was at least 46% higher than both the US [16] ground shipping service and Europe [12]; however, the maximum EFFDH level observed in China [13] was still at least 16% higher than in Korea. The EFFDH from the overall data at the 95% occurrence level in Korea was higher than both the ground shipping services of the USA and China by 4% and 79%, respectively. Table 4 and Figure 5 present the EFFDH at a 95 th percentile level for the highest, 2 nd, 3 rd, and 4 th drops. It is important to report the EFFDH of the Nth highest drop height at the 95 th percentile level since they are the recommended datasets to utilize when developing a drop test according to ISTA guidelines [30]. The 95 th percentile of the highest EFFDH in this study was at least 28% and 17% higher than those in Europe [12] and recommended by ISTA 3A [22] for testing packages less than 37 kg, respectively. The Korean parcel delivery system also had a higher max EFFDH than most of the other compared regions except for China [13]. The Korean parcel delivery system had characteristics closer to the EFFDH of next-day shipping services in the USA [17]. Next-day shipping service in the USA had an approximately 4% higher maximum EFFDH and an approximately 2% less EFFDH at a 95 th percentile level [17]. This trend indicates that packages shipped in the Korean parcel ground shipping service environment will most likely experience higher shock levels compared to historically investigated ground shipping services in different regions, but their maximum possible shock levels would be less than in China. Both the number of drops and the EFFDH results prove the uniqueness of the Korean parcel delivery system and show the need to establish their own laboratory testing standards. Table 5 categorizes the drop orientations of the top four highest EFFDH events. The results indicate that the packages are dominantly (approximately 50%) impacted on the edges, followed by the corners (approximately 35%) and then the faces (approximately 16%) regardless of the package size or weight. The impacts were also concentrated on orientations that are on and around the bottom of the package. This seems to be due to the large tendency of the shipping label to be located on the top face of the package. It was observed during multiple site audits conducted by this study's authors in several hub and sub terminals located in Korea that packages are usually handled top face upwards to be able to scan the labels using either a fixed loop-style scanner or a handheld scanner. These results were in line with the previous study conducted in Europe [12] and the ISTA 3A standard [22]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{4}{c}{**95 th Percentile Equivalent Free-Fall Drop Height**} \\ \cline{2-5}  & **Highest** & **2 nd** & **3 rd** & **4 th** \\ \hline Medium + Small & 1290.57 mm (50.81 in.) & 751.08 mm (29.57 in.) & 610.87 mm (24.05 in.) & 456.18 mm (17.96 in.) \\ Medium & 1440.43 mm (56.71 in.) & 766.57 mm (30.18 in.) & 551.94 mm (21.73 in.) & 481.08 mm (18.94 in.) \\ Small & 1078.23 mm (42.45 in.) & 720.85 mm (28.38 in.) & 653.80 mm (25.74 in.) & 504.44 mm (19.86 in.) \\ Europe [12] & 812.8 mm (32 in.) & 660.4 mm (26 in.) & 584.2 mm (23 in.) & 533.4 mm (21 in.) \\ ISTA 3A [22] & 910 mm & & 460 mm & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Equivalent free-fall drop height (EFFDH) results for the nth drops height using the 95 th percentile.