1. Assistant Professor, Dept. of Industrial and Management Engineering, Myongji Univ., 116 Myongji-Ro, Cheoin-Gu, Yongin-Si, Gyeonggi-Do 449-728, Korea.
2. Program Manager II, Enterprise Cloud Mobility Group, One Microsoft Way, Microsoft Corporation, Building No. 40, Redmond, WA 98052.
3. Professor, School of Mechanical, Industrial and Manufacturing Engineering, Oregon State Univ., 204 Rogers Hall, Corvallis, OR 97331 (corresponding author).
4. Associate Professor, School of Mechanical, Industrial and Manufacturing Engineering, Oregon State Univ., 204 Rogers Hall, Corvallis, OR 97331.