Unionized workers at SC First Bank said Friday that they plan to hold a one-day rally in mid-September to protest the bank's move to adopt a merit pay system, showing no signs of easing tension between the two parties. Unionized members at the South Korean unit of Standard Chartered Plc went back to work on Monday, but they will stage slowdowns at bank branches under a pledge to continue a partial strike down the road. On Wednesday, the labor union held a one-day walkout.