SEOUL, Dec 10 (Reuters) - South Korea's biggest online retailer Coupang said on Wednesday that CEO Park Dae-jun has resigned, taking responsibility for a huge data breach at the company that has triggered a growing backlash in Asia's fourth-largest economy. Coupang "deeply apologises for causing concerns to the public," the company said in a statement, adding that it will work to restore customer trust and tighten security measures to prevent another data leak.