I would like to express my sincere thanks to my research advisor, Dr.Ohm
Pattanachoti for her invaluable help and constant encouragement throughout the course of this research. I am most grateful for Dr.Ohm Pattanachoti 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 research.
Finally, I most gratefully acknowledge my parents and my friends for all their support throughout the period of this research.