North Korea Thursday freed a South Korean worker it had detained since March, raising hopes of better relations after 18 months of bitter hostility from the communist state. The worker identified as 44-year-old Yu Seong-Jin was handed over to officials from his company Hyundai Asan, unification ministry spokesman Chun Hae-Sung told reporters. Yu is expected to cross the border Thursday evening, he said. Hyundai Group chairwoman Hyun Jung-Eun had crossed into the North Monday to seek the release of Yu, days after former US president Bill Clinton went to Pyongyang to secure the freedom of two American journalists.