Thanks to the ROK Drop blog for this excellent piece on the hijacking and Mr Hwang which includes several articles from 1969 and 1970:
August 10, 2015: North Korea has a long history of terrorism with the 1968 Blue House Raid when 31 North Korean operatives tried to assassinate South Korean President Park Chung-hee as the most audacious example. Once the commandos were detected the ensuing gunfights killed dozens of civilians and soldiers. A year later on December 12, 1969 the North Koreans would conduct a more conventional terrorist act by hijacking a civilian airliner flying from Gangneung to Gimpo carrying 46 passengers and four crew members. Continue reading at the ROK Drop blog.