Kosŏng is a kun, or county, in Kangwŏn province, North Korea. It lies in the southeasternmost corner of North Korea, immediately north of the Korean Demilitarized Zone. Prior to the end of the Korean War in 1953, it made up a single county, together with what is now the South Korean county of the same name. In a subsequent reorganization, the county absorbed the southern portion of Tongch'ŏn count…