## 5 Conclusions  
Overall, this study investigated the effect of the curvature of the edge screen on users' grip comfort, control comfort, stability, and visibility, based on subjective evaluation experiments. Especially, four representative usage patterns were defined and evaluated to investigate the interaction effect of curvature and usage patterns for grip comfort, control comfort, and stability. As a result, 8R was the most appropriate radius of curvature for edge screens when the overall results were considered. The results showed that the effect of curvature on grip and control comfort varies by usage pattern. This study can be used as fundamental research to understand the subjective feeling in smartphones with a curvature display, which is being developed recently. However, this study has limitations based on surveys without using quantitative indices such as electromyography (EMG). In a future study, these quantitative indices to determine the relationship between subjective feelings and muscle fatigue due to changes in curvature of the screen can be conducted. In addition, it is expected that it will be possible to study the optimum curvature of display for various types of hands by considering not only the length of the hand but also the hand measurements such as the circumference and the finger. All authors have substantially contributed to the conceptualization, methodology, formal analysis, investigation, resources, and data curation. [PERSON], [PERSON], [PERSON], and W.K. contributed to the writing original draft and editing. [PERSON], and [PERSON] contributed to the data collection and validation. W.K., and M.H.Y. contributed to the project administration, supervision, and funding acquisition. All authors have read and agreed to the published version of the manuscript. This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT: Ministry of Science and ICT) (No. 2020R1G1A1003384). The authors thank the administrative support from the Institute for Industrial Systems Innovation of Seoul National University. This research was supported by the BK21 Plus Program (Centre for Sustainable and Innovative Industrial Systems) funded by the Ministry of Education, South Korea. (No. 21A20130012638). The authors declare no conflict of interest. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Evaluation** \\ **Factor** \\ \end{tabular} } & \multirow{2}{*}{**Pattern**} & \multicolumn{2}{c}{**4R**} & \multicolumn{2}{c}{**6R**} & \multicolumn{2}{c}{**8R**} & \multicolumn{2}{c}{**10R**} \\ \cline{3-10}  & & & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** \\ \hline \multirow{3}{*}{\begin{tabular}{c} **Grip** \\ **Comfort** \\ \end{tabular} } & Pattern (a) & 4.700 & 1.572 & 4.700 & 1.265 & 4.800 & 1.305 & 4.450 & 1.431 \\  & Pattern (b) & 4.600 & 1.297 & 4.950 & 0.932 & 5.075 & 1.095 & 4.750 & 1.296 \\  & Pattern (c) & 4.625 & 1.531 & 4.675 & 1.269 & 4.975 & 1.230 & 5.200 & 1.224 \\  & Pattern (d) & 4.700 & 1.324 & 4.875 & 1.488 & 4.775 & 1.561 & 4.175 & 1.412 \\ \hline \multirow{3}{*}{\
\begin{tabular}{c} **Control** \\ **Comfort** \\ \end{tabular} } & Pattern (a) & 4.175 & 1.662 & 4.250 & 1.410 & 4.700 & 1.471 & 4.250 & 1.335 \\  & Pattern (b) & 3.850 & 1.578 & 4.450 & 1.358 & 4.775 & 1.441 & 5.050 & 1.300 \\  & Pattern (c) & 3.750 & 1.645 & 4.100 & 1.499 & 5.000 & 1.281 & 4.950 & 1.319 \\  & Pattern (d) & 4.350 & 1.610 & 4.525 & 1.450 & 4.425 & 1.534 & 4.175 & 1.466 \\ \hline \multirow{3}{*}{
\begin{tabular}{c} **Stability** \\ **Comfort** \\ \end{tabular} } & Pattern (a) & 5.000 & 1.450 & 4.950 & 1.218 & 5.075 & 1.095 & 4.575 & 1.299 \\  & Pattern (b) & 4.900 & 1.277 & 5.150 & 1.075 & 5.100 & 1.194 & 4.750 & 1.235 \\  & Pattern (c) & 4.950 & 1.377 & 4.975 & 1.143 & 5.200 & 1.091 & 5.450 & 1.154 \\  & Pattern (d) & 4.775 & 1.349 & 4.925 & 1.492 & 4.775 & 1.441 & 4.450 & 1.339 \\ \hline \hline \end{tabular}
\end{table}