Stability of linear dynamic systems on time scales. Choi, Sung Kyu; Im, Dong Man; Koo, Namjip — 2008 Advances in Difference Equations [electronic only]
Total stability in nonlinear discrete Volterra equations with unbounded delay. Choi, Sung Kyu; Goo, Yoon Hoe; Im, Dong Man; Koo, Namjip — 2009 Abstract and Applied Analysis