[1] Sungkyunkwan Univ, Sch Med, Div Pulm & Crit Care Med, Dept Med, Seoul, South Korea
[2] Sungkyunkwan Univ, Sch Med, Samsung Med Ctr, Dept Thorac Surg, Seoul, South Korea
[3] Chungbuk Natl Univ Hosp, Dept Thorac Surg, Cheongju, Chungbuk, South Korea