## 5 Summary and Conclusions  
In this study, two types of suspended SFTs were proposed to analyze their hydrodynamic behavior. The main variables were the wave conditions, cross-sectional diameters, buoyancy weight ratios, inclination angles of the main cables, and installation depth of the SFT.  
* Wave condition: as the significant wave height increased, the motion of both Type 1 and Type 2 was increased.
* BWR: The behavior of Type 1 and Type 2 differed, depending on the BWR. For Type 2, the acceleration, reaction force, and section force were all increased, as negative motion occurred due to the slack in the BWR 1.1. On the other hand, for Type 1, as the BWR increased, the heave motion increased, and the acceleration, reaction force, and section force increased proportionally.
* Inclination angle of the main cables: it can be seen that the behavior of Type 1 and Type 2 differed, as the inclination angle of the main cables increased. In the case of Type 2, the acceleration, section force, reaction force, etc. increased as the motion in the wave acting direction increased. In contrast, the behavior of Type 1 decreased as the angle increased.
* Diameter of the tube: The acceleration, section force, and reaction force increased as the diameter of the tube grew under the aforementioned conditions. It can be seen that the SFT with the tube of a large diameter is disadvantageous economically and mechanically.
* Installation depth of the SFT: as the installation depth of the SFT increased, the wave breaking impact generally decreased, and the motion decreased. However, in the case of a depth of 40 m, Type 2 experienced slack, and the acceleration, section force and reaction force were greatly increased, which is a condition that should be avoided.
* Comprehensive remarks: overall, it can be seen that the Type 2 SFT was superior from a hydrodynamic point of view. However, a detailed hydrodynamic analysis must be performed to avoid the conditions that previously produced slack. In addition, in the case of acceleration being generated by motion, the design should be reviewed to ensure safe conditions, according to the traffic passage.  
Figure 17: Behavior of the SFT, according to the installation depth: (**a**) maximum motion of the SFT; (**b**) heave motion at each point of the SFT; (**c**) maximum acceleration of the SFT; (**d**) maximum reaction force on the foundation of the SFT; (**e**) maximum section force of the SFT; (**f**) maximum section moment of the SFT.  
**Author Contributions:** conceptualization, W.-S.P. and Y.Y.; software, S.K.; formal analysis, D.W.; investigation, D.W. and S.K.; resources, D.W.; data curation, J.S.; writing--original draft preparation, D.W and J.S; writing--review and editing, D.W. and J.S.; visualization, D.W.; supervision, W.-S.P; project administration, W.-S.P.; funding acquisition, W.-S.P.  
**Funding:** This work was supported by the National Research Foundation of Korea (NRF), the grant for which was funded by the Korea government (MSIT) (No. 2017R1A5A1014883).  
**Conflicts of Interest:** The authors declare that they have no conflicts of interest.  
**Abbreviations**  
\begin{tabular}{l l} \(A\) & the cross-sectional area \\ \(C_{A}\) & the added mass coefficient (with a cross-sectional area as a reference area) \\ \(C_{D}\) & the drag coefficient \\ D & the diameter \\ \(f_{drag}\) & the sectional drag force \\ \(f_{L}\) & a loft force \\ \(f_{N}\) & normal force \\ \(f_{T}\) & a tangential force \\ \(m_{T}\) & a torsion moment \\ \(v\) & the fluid particle (waves and/or current) velocity \\ \(\dot{v}\) & the fluid particle acceleration \\ \(\rho\) & the mass density of the fluid \\ \(\lambda\) & the wavelength \\ \end{tabular}