[1] Hallym Univ, Kangnam Sacred Heart Hosp, Dept Pediat, Seoul, South Korea
[2] Seoul Natl Univ, Grad Sch Publ Hlth, Dept Publ Hlth Sci, Seoul, South Korea
[3] Soonchunhyang Univ, Coll Med, Seoul Hosp, Pediat Allergy & Resp Ctr,Dept Pediat, Seoul, South Korea