SEOUL - South Korea’s parliament on Thursday gave the green light for an investigation into ballot paper shortages that disrupted municipal elections this month and fueled political tensions.Dozens of polling stations experienced unprecedented ballot paper shortages on June 3 for the first nationwide vote since President Lee Jae Myung took office a year ago.The controversy prompted the resignation of National Election Commission (NEC) chief Roh Tae-ak and sparked demonstrations by South Koreans demanding a re-election.