Systems & Software Research Laboratories, Toshiba Corporation, 70, Yanagi-cho, Saiwai-ku, Kawasaki-shi, Kanagawa 210-8501, Japan;Systems & Software Research Laboratories, Toshiba Corporation, 70, Yanagi-cho, Saiwai-ku, Kawasaki-shi, Kanagawa 210-8501, Japan;Systems & Software Research Laboratories, Toshiba Corporation, 70, Yanagi-cho, Saiwai-ku, Kawasaki-shi, Kanagawa 210-8501, Japan;Systems & Software Research Laboratories, Toshiba Corporation, 70, Yanagi-cho, Saiwai-ku, Kawasaki-shi, Kanagawa 210-8501, Japan