Acknowledgements

We would like to express our gratitude to Mr. Akira Anju of Kozo Keikaku Engineering Inc. for various advices on numerical calculation. A part of this research is supported by Fukui Prefecture's FY 2004 University Collaborative Research Promotion Project (representative, Prof. Keisuke Kojima) and Grants-in-Aid for Scientific Research (C) (16 K01316) (representative, Michihiro Ohori).
