.... The outline of the project was mentioned by Ishida et al. (2008). In the safety design of platforms, the sea conditions in the longer return period than the planned operation period is usually assumed. The guidelines for setting the sea conditions for safety design in the areas of crude oil / natural gas...

... on the cylinder. One of the authors Ishida(Ishida and Tamura,1988) has theoretically analyzed the wave forces acting on a Circular cylinder installed in the wave field to make clear the generation mechanism of drag forces due to wake vortices. This paper further aims at the establishment of theoretical analysis...

... ishida irregular wave displacement vibration experiment water level variation cancellation point wave force linearized method subsea system offshore platform cosh suppression upstream oil & gas spectral density variation theoretical solution equation frequency resonance...

...), and Ishida and Konda (1984), Ishida (1985) has done such a research by using the matrix methods. However, there still remains some problems on the characteristics of resonance, especially on the approach to suppress the resonance. Concerning the technique for suppressing the resonance in the case of offshore...