1. Dept. of Statistics, Faculty of Sciences, King Abdulaziz Univ., Jeddah 21551, SA, e-mail: oharif@hotmail.com
2. Dept. of Statistics, Faculty of Sciences, King Abdulaziz Univ., Jeddah 21551, SA, (Corresponding author) e-mail: aslam_ravian@hotmail.com
3. Dept. of Industrial and Management Engineering, POSTECH, Pohang 790-784, KR, e-mail: chjun@postech.ac.kr