## 6 Results and Discussion  
As shown in Figure 20, the air effect phenomenon appeared in the cylinder shape as well as the flat model. This acts as a deterrent to the increase in pressure. In general, slamming pressure is highest when the dead-rise angle is 3 to 10 degrees. It was confirmed from the pressure history that the air \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **1 st** & **2 nd** & **3 rd** & **4 th** & **5 th** \\ \hline Measurement [mm] & 80 & 100 & 120 & 130 & 140 \\ Simulation [mm] & 105 & 115 & 125 & 135 & 145 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Max. Displacement at center line. Figure 19: Measurement of the 1 st free drop test (**left**) and the 5 th free drop test (**right**). effect, such as in the flat shape at the thickness of the cylinder shape and a bottom thickness of 5 and 8 mm, occurs. Also, Figure 20 shows an enlarged pressure history of a cylindrical shape model. It seems that the pressure shape of the enlarged graph shows two peaks due to the air effect. As with the flat shape, it does not reach the maximum pressure and shows the effect of dispersion. Figure 9 shows the pressure and strain time history of the free-drop test of the model with a deadrise angle of 10\({}^{\circ}\) dropped from a height of 1.0 m. It confirms that the time at which the pressure was generated differs according to the angle formed by the deadrise angle, and that the strain exhibits the same behavioral characteristics. This means that the elastic period of the elastic body coincides with the natural frequency. Figure 10 shows the pressure and strain time history of the free-drop test of the model with a deadrise angle of 10\({}^{\circ}\) dropped from a height of 1.7 m. The characteristics of the natural frequency of the structure are more clearly shown in Figure 10. At 0.585 s, the first peak pressure was generated due to the free-drop impact, and the second peak pressure and the third peak pressure are confirmed at approximately 0.625 and 0.655 s, respectively, i.e., after 0.03 s. This is indicated by a red square in Figure 10. The behavior of the strain oscillation was confirmed to be very similar to that of the pressure history. Figure 11 shows the pressure and strain time history of the free-drop test of the cylindrical model dropped from a height of 1.0 m. It confirms that strain exhibits the same behavioral characteristics as pressure history does. This means that the elastic period of the elastic body coincides with the natural frequency. Figure 12 shows the pressure and strain time history of the free-drop test of the cylindrical model dropped from a height of 1.7 m. The characteristics of the natural frequency of the structure are more clearly shown in Figure 12. At 0.60 s, the first peak pressure was generated due to the free-drop impact, and the second peak pressure was confirmed at approximately 0.63 s, i.e., after 0.03 s. This is shown in a red square in Figures 10 and 12. The behavior of the strain oscillation was confirmed to be very similar to that of the pressure history. Figure 20 and Table 8 show the pressure time history and impulse values measured in the free-drop experiment of the model with a deadrise angle of 10\({}^{\circ}\) and the cylindrical model. The highest value of pressure was measured in the cylindrical model relative to the flat model and the model with a deadrise angle of 10\({}^{\circ}\). In the case of the model with a deadrise angle of 10\({}^{\circ}\), the maximum pressure when dropped from a height of 1.0 m was 0.29 MPa, with a maximum strain of 0.0010, and the maximum pressure when dropped from a height of 1.7 m was 0.45 MPa, with a maximum strain of 0.0010. In the case of the cylindrical model, the maximum pressure when dropped from a height of 1.0 m was 0.78 MPa, with a maximum strain of 0.0010, and the maximum pressure when dropped from a height of 1.7 m was 0.98 MPa, with a maximum strain of 0.0012. Slamming pressure and strain were shown to increase with drop height and thickness by [25].