1. Hino Campus Tokyo Metropolitan University Asahigaoka Hino‐shi Tokyo Japan
2. National Institute of Technology Ibaraki College Nakane Hitachinaka Ibaraki Japan
3. Graduate School of Information Science and Technology Hokkaido University Kita‐ku Sapporo Hokkaido Japan
4. Hitachi Power Semiconductor Device, Ltd. Omika‐cho Hitachi Ibaraki Japan
5. Railway System Business Unit Hitachi, Ltd. Soto‐kanda Chiyoda‐ku Tokyo Japan