JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 50, no. 5, page. 1372 - 1376, 2007-05
JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 53, no. 6, page. 3741 - 3743, 2008-12
JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 54, no. 1, page. 381 - 385, 2009-01