[1] NTT Ener./Environ. Syst. Lab., NTT Corporation, Musashino-shi, 180-8585, Japan
[2] Kyushu Institute of Technology, Kitakyushu-shi, 804-8550, Japan
[3] Telekom Malaysia R and D Berhad, UPM-MTDC, 43400 UPM Serdang, Malaysia
[4] Universiti Teknologi Malaysia, Locked Bag 80990, Johor Bahru, Johor, Malaysia