Stielike's men just missed out on the Asian Cup title in January, as they lost the final 2-1 in extra time to host nation Australia.
With the Asian Football Confederation's (AFC) second round of qualifying for Russia 2018 set to begin on June 11, Stielike does not believe he needs to make major changes to his squad but maintains tweaks are required to make South Korea Asia's leading team.
The German coach has brought in six players for this week's friendlies against Uzbekistan and New Zealand, and all of them are under the age of 27.
"Players showed great performances as we ended up the Asian Cup in second place," Stielike said when announcing his squad.
"I didn't have to change the roster much. However, we need some of changes as well in order to develop ourselves to become first place, not second place."
Stielike is particularly interested in taking a look at Ji and Kim Bo-kyung, with both players having broken into their club's starting XI since the Asian Cup.
"Kim Bo-kyung is almost a key player in Wigan; Ji Dong-won also played six matches out of seven matches as a starting member as he transferred to Augsburg from [Borussia] Dortmund," Stielike said.
"I called up two players in order to check their abilities by myself."
The visitors will no doubt be keen for revenge after losing 2-0 after extra time to Stielike's side in the Asian Cup last-eight.
