NASA MANAGERS have delayed launch of the shuttle Discovery from next week to late April, after a flight by the shuttle Atlantis, because of cracked hinges in critical fuel line doors . . . THAILAND'S King Bhumibol Adulyadej formally approved a revised interim constitution Friday in preparation of a civilian government under the supervision of the military junta that seized power six days ago . . . SOUTH KOREAN President Roh Tae-woo said Friday the two Koreas, divided for more than 45 years, could be reunited within the next five years.