I would like to express my sincere thanks to my research advisor, Dr. Pablito M. Madalita for him invaluable help and constant encouragement throughout the course
of this research. I am most grateful for him teaching and advice, not only the research
methodologies but also many other methodologies in life. I would not have achieved
this far and this research would not have been completed without all the support that I
have always received from him.