## 7 Conclusions  
In this study, various free-drop experiments were performed using a steel model with a deadrise angle of 10\({}^{\circ}\) and a cylindrical model, which were dropped from heights of 1.0 and 1.7 m. The results are compared with those obtained by employing a rigid wooden model. The difference in results confirms the effect of elasticity of the material on the slamming load. The purpose of this experiment is to identify the pressure and behavioral characteristics of the model. Figure 21: Simplified triangular pressure. Figure 22: Comparison of peak pressures. It was observed that the slamming load was greater in the case of the cylindrical model compared to the cases of the flat model and model with deadrise angle of 10\({}^{\circ}\), as shown in Figure 22. A second peak was confirmed in the case of the model with a deadrise angle of 10\({}^{\circ}\), occurring approximately 0.03 s after the first peak. This was confirmed by the theoretically calculated natural frequency of the structure (34.85 Hz) being very close to the experimentally obtained value (33.33 Hz). Additionally, the value obtained from the hammer test was 34.15 Hz, which was substantially similar to the experimental value. The second peak obtained was higher than the first peak. In the case of the cylindrical model and drop height of 1.7 m, it was observed that the first peak occurred at 0.60 s and the second peak occurred approximately 0.03 s after the first peak, i.e., at 0.63 s. Furthermore, this was confirmed by the theoretically calculated natural frequency of the structure (34.15 Hz) being very close to the experimentally obtained natural frequency (33.33 Hz). The value obtained from the hammer test was 35.5 Hz, which was substantially similar to the experimental value. It was confirmed that even with a single wave, the impact pressure occurs several times according to the natural frequency of the structure. This means that the structure can be permanently damaged even by a single wave, and fatigue failure can occur due to repetitive slamming. These results can resolve the lack of information on slamming loads. The results obtained in this study can aid in the development of design techniques; the effect of slamming pressure can be incorporated into the fundamental design of parameters to prevent structural damage. Negative pressure occurs due to the elastic effect of the structure--it was confirmed that the duration of the pressure was longer. In addition, in the case of the cylindrical shape, the first peak is larger compared to other structures, but the size of the second peak tends to decrease. The study of slamming turns out to be an important factor to consider the elastic effects of the structures. It seems that the second peak pressure occurs when the negative pressure, due to the elastic effect, was close to \(-\)0.1 Mpa. These results are expected to be reflected in structural design via comparison with the peak width and natural frequency of the structure. Therefore, the design considering the elastic influence of the structure should be carried out and structural damage of offshore structures and floating offshore wind turbines are expected to be reduced. The dynamic nonlinear analysis was performed using ABAQUS software. In the analysis, slamming loads obtained from the free-drop experiments were used, and the accuracy of the numerical prediction was acceptable, as seen from the experimental results. However, further studies are needed to ensure accuracy and reliability, and additional experiments are required to be performed under the same conditions to ensure confidence in results. Conceptualization, validation, B.S. and H.S. ; methodology, software, writing--original draft preparation, B.S. ; writing--review and editing, supervision, H.S. All authors have read and agreed to the published version of the manuscript.