Steven Nzonzi has handed in a transfer request at Stoke, while keeper Asmir Begovic is eyeing a move to Liverpool.
Christian Benteke has hinted he will leave Aston Villa this summer.
Yun Suk-young became Harry Redknapp's third signing as QPR manager after joining from Chunnam Dragons on a three-and-a-half-year deal.
The 22-year-old was a key member of the South Korean Olympic squad that took bronze at London 2012, before then going on to make his full international debut in October.
Yun has been linked to a number of clubs in recent times, including west London rivals Fulham, but has joined QPR on for an undisclosed fee from K-League side Chunnam Dragons.
The left-back has been granted a work permit and will be eligible to play for the Rs once he obtains a visa.
Yun joins fellow January acquisitions Loic Remy and Tal Ben Haim at Loftus Road, where he links up with countryman Park Ji-sung.