I would also like to thank to Assistant Professor. Worapong Khundejamorn for his invaluable help and constant encouragement throughout the course of this report. I would not have achieved and this report would not have been completed without all the support that I have received from his. I would also like to acknowledge my friends as the second reader of this report, and I am gratefully indebted to them for them very valuable comments on this report.
Finally, I must express my very profound gratitude to my parents and to my friend for providing me with unfailing support and continuous encouragement throughout of study. This accomplishment would not have been possible without them. Thank you.