Firstly, I would like to express my sincere gratitude to my advisor, Assistant Professor
Dr.Supaporn Suksern, for the continuous support of my study and related research, for
her patience, motivation and immense knowledge. I would not have achieved this far and
this thesis would not have been completed without all the support that I have always
received from her.
Besides my advisor, I would like to thank the rest of my thesis committee Assistant
Professor Dr.Sopita Khamrod and Dr.Jakkrid Sompong for their insightful comments and
encouragement, but also for the hard question which incented me to widen my research
from various perspectives and providing me with valuable comments on earlier versions
of this thesis.