## 2 Materials and Methods
### Sizing System Development
#### 2.3.1 Segmenting the Size Section
size sections with a total coverage rate of 95.5% were generated based on height and hip circumference data through the interpretation of the cross-tabulation, as shown in Table 6.  
Figure 2: Section removal and grouping process of primary cross-tabulation: (**a**) section removal and (**b**) section grouping. In the secondary cross-tabulation analysis, after data coding of the height and hip circumference important variable dimension into 25 sections and the lower-drop important variable dimension into 10 sections, cross-tabulation analysis was performed to determine the distribution of the size section between the height and hip circumference and the lower-drop variable. The calculation results of secondary cross-tabulation are shown in Table 7. The chi-square value was 269.041, and the \(p\)-value was 0.008. Since \(p<0.05\), it was confirmed that the difference between groups was statistically significant. In the height and hip circumference, section 10 showed the highest frequency with 6.8%. In the lower-drop, sections 5 and 6 showed the highest frequency with 16.8%. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Section**} & **Height** & **Hip Circumference** & \multirow{2}{*}{**Freq.**} & **Coverage Rate** \\  & **(mm)** & **(mm)** & & **(\%)** \\ \hline  
\multicolumn{5}{c}{Total} & 190 & 95.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Results of primary cross-tabulation analysis. The process of section removal and grouping in secondary cross-tabulation analysis is as follows. In the cross-tabulation, the initial 250 were filtered down to 225 by removing the lower-drop section 10, which was the maximum-minimum extreme section with a total appearance frequency of less than 2%. Next, 108 sections with an appearance frequency of 0% were deleted to filter the 225 sections down to 117, and seven sections showing the lowest appearance frequency in the maximum-minimum extreme section of height and hip circumference were removed to provide 110 sections (Figure 3a). Then, those sections were grouped based on the coverage rate of 2 to 4.3% to filter the 110 sections into 34 (Figure 3(b1,2)). These were grouped again based on the coverage rate of 4.2 to 7.3% to filter the 34 sections into the final 18 (Figure 3c). In the secondary cross-tabulation analysis, 18 final sections with a total coverage rate of 90.5% were generated based on height, hip circumference, and lower-drop data from the interpretation of the cross-tabulation, as shown in Table 8.  
The number of general size sections applied to clothes, shoes, gloves, hats, etc., ranges from 5 to 10. Considering that these products are products with relatively high design tolerances compared to the products under study, it was considered appropriate to determine the number of size sections of body shape fit between 15 and 20. In addition, assuming that the number of size sections is, at most, 20, the coverage rate of each size section is selected based on an approximate value of 5%. Based on the criteria for excluding extreme sections of less than the 5 th % and more than the 95 th % in product size design reflecting human dimensions, the total coverage rate was set as a target of 90%. The proposed size system-based 3 DP-pHRI is a method that selects the 3 DP-pHRI size system that is closest to the human body shape of the wearer from the previously developed (libraryized) pHRI and produces it using 3D printing. In this respect, the number of size sections is not subject to a large limitation; however, setting a size section that is too compact can complicate the process of selecting a size system suitable for the wearer. Accordingly, 18 size sections were finally selected in consideration of the human fitness (total coverage rate: 90.5%), as shown in Table 8.  
The characteristics of each section of the selected size section are as follows.