 He has also made pivotal contributions to mesoscopic self-organization in solids, including the nanoscale charge stripe formation, mesoscopic electronic phase separation in mixed valent transition metal oxides, and the formation of topological vortex domains in multiferroics, which was found to be synergistically relevant to mathematics (graph theory) and cosmology.Cheong graduated in Mathematics from Seoul National University in 1982 and then studied physics in graduate school at the University of California, graduating from there in 1989.From 1986-89 Cheong worked at the Los Alamos National Laboratory before joining AT&T Bell Laboratories.