Samsung Electronics, Hyundai Motor and other major South Korean manufacturers on Sunday unveiled domestic investment plans, as a US trade deal raised concerns that investment in the US could weaken manufacturing at home.Samsung Electronics will add a chip production line at its plant in the South Korean city of Pyeongtaek to meet rising demand amid the global boom in artificial intelligence, as part of the parent group’s 450 trillion won (US$310.79 billion) investments at home over the next...