SEOUL (Reuters) -A workers' union at Samsung Electronics staged its first walkout on Friday, signalling more assertiveness among employees just as South Korea's most powerful conglomerate races to catch up in chips used in artificial intelligence. The National Samsung Electronics Union (NSEU), whose roughly 28,000 members make up over a fifth of the firm's workforce, said it would stop work for a day to demand better pay. The walkout is unlikely to immediately impact semiconductor production or shipments but will add pressure on Samsung Electronics as it chases AI and narrows a gap in contract chip manufacturing with Taiwan's TSMC, analysts said.