1. Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305-8687, Japan
2. Tohoku Research Center, Forestry and Forest Products Research Institute, Morioka, Iwate 020-0123, Japan
3. Hokkaido Research Center, Forestry and Forest Products Research Institute, Sapporo, Hokkaido 062-8516, Japan
4. Kyushu Research Center, Forestry and Forest Products Research Institute, Kumamoto, Kumamoto 860-0862, Japan