SEOUL, South Korea (AP) — South Korean tech giants Samsung Electronics and SK Hynix said Monday they will invest a combined 800 trillion won ($518 billion) in building a new computer chipmaking hub in the country’s southwest region, capitalizing on surging artificial intelligence -driven demand. President Lee Jae Myung joined the companies’ chairs Monday in announcing the plan, which dovetails with the government’s efforts to expand investment beyond the greater Seoul metropolitan the...