First Author:   Yoshimasa Uematsu The Institute of Statistical Mathematics uematsu@ism.ac.jp   10-3 Midori-cho Tachikawa, 190-8562, Japan       Second Author: Shinya Tanaka Otaru University of Commerce stanaka@res.otaru-uc.ac.jp   3-5-21 Midori Otaru, 047-8501, Japan