Hammond told the club website: “Seol was the first player to come in, and he was very much one of our primary targets. He’s played in two World Cups, and has the right professionalism and personality.
“We felt he had much more to offer than he’d already shown in England, and was potentially more suited to Premiership than Championship football.
“He was a player we thought could unlock the door, which is something you need in the top division.
“When you look at the market this summer, at an initial fee of £1million I’m delighted with the deal.”
Seol scored his first Premiership goal in the 2-1 win against Sheffield United on September 16, 2006.