Acknowledgement
We would like to express our sincere thanks to our report advisor, Asst.Prof.Dr.Bussaba Sitikarn for her invaluable help and constant encouragement throughout the course of this report. We are most grateful for her teaching and advice, not only the report methodologies but also many other methodologies in life. We would not have achieved this far and this report would not have been completed without all the support that we have always received from her.
Finally, I most gratefully acknowledge my parents and my friends for all their support throughout the period of this report.