Ulsan regained second place in the K-League table with their third win of the season, a 3-0 home win over Gangwon on Sunday.
First-half goals from Shin-Wook Kim after 16 minutes and Seung-Yong Kim 12 minutes before half-time put Ulsan in the box seat for a comfortable win.
Yong-Ji Park completed the scoring in the 84th minute to give Ulsan nine points from four matches, one behind leaders Pohang Steelers.
Sunday's other match saw Daejeon Citizen earn their first victory of the season, a 2-1 win at Incheon United.
Woong-Hee Lee gave the Citizens the lead two minutes before half-time but Jae-Joon Ahn hit back for the home side with the equaliser three minutes into the second half.
Four minutes later Joao Paulo grabbed the winner for Daejeon who move to ninth place.