My foremost thank goes to my main supervisor, Associate Professor Terence Hung for all of his efforts, inspiration and support in my graduate study. I thank him for his understanding, optimistic guidance, and constructive comments on my work that helped to shape my research skills. As well, I wish to express my sincere gratitude to my first co-supervisor Associate Professor Bu-Sung Lee for his patience and professional feedback. Since the beginning of my PhD, he has motivated me to realize and develop my potential in research. I am also sincerely grateful to my second cosupervisor Dr. Zheng Qin for his scientific and impeccable guidance in my research period. Further, I must show my great gratitude to Dr. Xiaorong Li for her continued support, encouraging meetings and helpful suggestions. I will forever be thankful for her kind efforts for giving me the opportunity to pursue my PhD study in Singapore.