1. School of Industrial Management Engineering, Korea University, Seongbuk-Gu, Seoul, Korea
2. Department of Statistics, Keimyung University, Daegu, South Korea
3. School of Electrical Engineering, Korea University, Seongbuk-gu, Seoul, Korea
4. Graduate School of Management of Technology, Korea University, Seongbuk-gu, Seoul, Korea
5. Division of Biostatistics, Department of Population Health, New York University School of Medicine, New York, N.Y., U.S.A.