On the Number of Guard Edges of a Polygon. Jung-Heum Park; Sung Yong Shin; Kyung-Yong Chwa; T.C. Woo — 1993 Discrete & computational geometry
Carrying umbrellas: An online relocation game on a graph. Lee, Jae-Ha; Park, Chong-Dae; Chwa, Kyung-Yong — 2001 Journal of Graph Algorithms and Applications