## 3 Results and Discussions
### Effects of T/T\({}_{f}\) and \(h\)/\(h_{\text{f}}\) on \(P_{wec}\)
Open red and blue circles denote the ranges of high and low \(k_{e}\). In each \(T/T_{f}\), the proportions of the valid pattern (patterns A and B) that accomplish power generation are 66.0% at \(T/T_{f}\) = 1.5 (0.17 \(<\) D/\(L\)\(<\) 0.24), 58.2% at \(T/T_{f}\) = 1.3 (0.19 \(<\) D/\(L\)\(<\) 0.29), 58.7% at \(T/T_{f}\) = 1.1 (0.24 \(<\) D/\(L\)\(<\) 0.34), 49.2% at \(T/T_{f}\) = 0.9 (0.30 \(<\) D/\(L\)\(<\) 0.43), and 33.4% at \(T/T_{f}\) = 0.7 (0.42 \(<\) D/\(L\)\(<\) 0.59). Excluding the case of \(T/T_{f}\) = 0.7 where the pendulum is located near \(D/L\) = 0.5, it can be confirmed that power can be generated in more than half of the cases, regardless of \(h/h_{f}\) and \(H_{ij}\)/\(L\) for the respective values of \(T/T_{f}\). Additionally, because the ratio of the number of cases at \(h/h_{f}\)\(\geq\) 1.07, where the water depth was greater than that of the flap, to the number of cases for overall patterns A and B, was 29.5% at \(T/T_{f}\) = 1.5, 25.6% at \(T/T_{f}\) = 1.3, 32.4% at \(T/T_{f}\) = 1.1, and 27.3% at \(T/T_{f}\) = 0.9; it is obvious that \(T/T_{f}\) does not have a significant effect on power generation under the condition of \(h/h_{f}\)\(\geq\) 1.07. Therefore, when considering pattern B, which is not included in the analysis, it is noticed that power can be generated at all wave periods except \(T/T_{f}\) = 0.7, regardless of the flap installation depth. However, because it is difficult to specify the output power in pattern B as described above, further study is necessary under the condition that the long period component due to multiple reflections is not included. Although the effect of \(h/h_{f}\) on patterns A and B is not significantly noticeable, the ratio of the number of cases at \(h/h_{f}\)\(\geq\) 1.0 for the respective values of \(T/T_{f}\) to the total number of cases of patterns C and D is extremely high, i.e., 76.9% at \(T/T_{f}\) = 1.5, 73.7% at \(T/T_{f}\) = 1.3, 70.0% at \(T/T_{f}\) = 1.1, and 73.9% at \(T/T_{f}\) = 0.7. As depicted in Figure 9a, the behavior of the flap tends to be unstable as the water depth increases. Therefore, as depicted in Figure 8b, when the flap is installed at \(h/h_{f}\)\(\geq\) 1.0 greater than the flap height, the condition of wave power in the installation area should be considered to avoid instability of the flap. In other words, it is better to avoid a submerged type of flap in the area of relatively low wave energy. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Pattern**} & \multirow{2}{*}{\(h/h_{f}\)} & \multicolumn{2}{c}{\(T/T_{f}\) = 0.7} & \multicolumn{2}{c}{\(T/T_{f}\) = 0.9} & \multicolumn{2}{c}{\(T/T_{f}\) = 1.1} & \multicolumn{2}{c}{\(T/T_{f}\) = 1.3} & \multicolumn{2}{c}{\(T/T_{f}\) = 1.5} \\ \cline{3-10}  & & **No. ** & **Total No. ** & **No. ** & **Total No. ** & **No. ** & **Total No. ** & **No. ** & **Total No. ** \\ \hline \multirow{8}{*}{A} & 1.11 & 0 (0.0) & & 1 (9.1) & & 5 (22.7) & 0 (0.0) & & 5 (12.5) & \\  & 1.07 & 0 (0.0) & & 0 (0.0) & & 6 (27.3) & & 2 (6.4) & & 8 (20.0) & \\  & 1.0 & 1 (25.0) & 4 (6.1) & 1 (9.1) & 11 (16.9) & 3 (13.6)