80 страниц. 2011 год. LAP Lambert Academic Publishing I would like to take this opportunity to express my thanks and gratitude to my Supervisor, Associate Professor Fadzilah Siraj, for her guidance, wonderful support and efforts in assisting me carrying out these research and thesis to become a reality. Last but not least, my gratitude also goes to my beloved family members who have done great job of supporting me throughout this research. They have been very understanding and offered lots of encouragement when the system and research I was working on did not seem to work the way it should be. To those I have not mentioned above, but had ever helped me, I really appreciate it and felt very thankful for all your helps. Thanks to all of you once again!