Affiliation: | aDepartment of Mathematics, The Catholic University of Korea, Bucheon 420-743, Republic of Korea;bDepartment of Naval Architecture and Ocean Engineering, Seoul National University, Seoul 151-744, Republic of Korea;cResearch Institute of Marine Systems Engineering, Seoul National University, Seoul 151-744, Republic of Korea;dDepartment of Mathematics, Seoul National University, Seoul 151-747, Republic of Korea;eResearch Institute of Mathematics, Seoul National University, Seoul 151-747, Republic of Korea;fDepartment of Mathematics, Dongguk University-Seoul, Seoul 100-715, Republic of Korea;gSTX R&D Center, STX Offshore and Shipbuilding Co. Ltd., Changwon 641-060, Republic of Korea |