http://www.osaka-ue.ac.jp/file/general/5177 - 植民地朝鮮における石炭産業 - 大阪経済大学] The first of these extensions was a 5 kilometers stretch from Bukchang to Okcheon opened on 28 December 1944, 朝鮮総督府官報 (The Public Journal of the Governor-General of Korea), Shōwa No.