SEOUL (Reuters) -North Korea appears to have returned to an upright position its stricken Choe Hyun Class destroyer that partially capsized during a botched launching ceremony, U.S. researchers said on Wednesday. Leader Kim Jong Un, who witnessed the failed launch of the 5,000-tonne warship, said the accident damaged the country's dignity and vowed to punish those found responsible. Commercial satellite imagery from June 2 showed the destroyer upright for the first time since the May 21 accident, the 38 North programme, which studies the nuclear-armed North, said in a report.