PANGYO, South Korea, June 10 : Unionised workers at South Korean tech firm Kakao began a four-hour strike and rally on Wednesday, demanding job security and changes to the company's bonus system. The strike will run from 10 a.m. to 3 p.m. (0100 GMT to 0600 GMT), with workers set to join a rally at a square near Kakao's office in Pangyo, Gyeonggi province, a union leader said in a text message. The rally will include a march from the subway station, the union said. The dispute comes amid signs