1. Inorganic Standards Group, Research Institute for Material and Chemical Measurement (MCM), National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), No. 1-1-1, Umezono, Tsukuba, Ibaraki 305-8563, Japan
2. Electronics Equipment Division, Hakuto Co., Ltd., No. 1-13, Shinjuku 1-Chome, Shinjuku-Ku, Tokyo 160-8910, Japan