[1] Jeju Natl Univ, Sch Med, Dept Psychiat, Cheju, South Korea
[2] Nathan S Kline Inst Psychiat Res, Orangeburg, NY 10962 USA
[3] Univ Illinois, Dept Disabil & Human Dev, Chicago, IL USA
[4] Yonsei Univ, Dept Psychiat, Seoul 120749, South Korea
[5] Yale Univ, Sch Med, Ctr Child Study, New Haven, CT 06510 USA
[6] Chonbuk Natl Univ, Sch Med, Dept Psychiat, Jeonju 561756, South Korea
[7] Chonbuk Natl Univ, Chonbuk Natl Univ Hosp, Biomed Res Inst, Res Inst Clin Med, Jeonju 561756, South Korea
[8] Jeonbuk Internet Addict Ctr, Jeonju, South Korea
[9] Jeonju Dong Middle Sch, Jeonju, South Korea