Korean preparations for World Cup ended in disarray as their west African opponents won 4-0 but the Mainz midfielder believes the squad are in the right frame of mind
The Asian side begin their Group H campaign on Tuesday in Cuiaba against Russia but their warm-up matches have not been positive.
Ghana defeated the Taeguk Warriors 4-0 in Miami in their final friendly before the tournament and Hong Myung-Bo's side have won only two of six matches in total in 2014.
Nonetheless, Mainz midfielder Koo believes the Ghana result has helped the squad frame things positively.
"After the Ghana match, the atmosphere was not great," he admitted. "But, thanks to that match, we talked a lot and thanks to those talks we were able to share our thoughts.
"We discussed how we need to be able to take chances and why we allowed them to have goals so easily.
"While we were training and preparing for Russia we created a positive atmosphere and became more confident. We are fully prepared and confident for tomorrow's match.
"The process up to now hasn't been easy. We have been on the pitch and experienced difficulties. We know what we have to do. We learned our lessons as to what has to be done at the World Cup."
Korea coach Hong Myung-Bo knows the importance of a strong start in Group H with Algeria and Belgium also vying for qualification. He says his primary focus against Fabio Capello's Russians will be avoiding defeat.
"The first match sets the tone and it does impact the rest of the matches," he said. "In our case, we would like to win the first match but we have to make sure we play a game we don't lose."
The sides met in November in a friendly and, despite being on the wrong end of the result, Hong has taken the positives from that display.
"We know the competition is very different. Last time we met in Dubai we lost 2-1 but we thought we played a good game. Thanks to that match our players became confident so it was a good match.
"Capello is a world famous coach so I am sure that will impact the Russian team to a certain extent. But our players will not be affected by that. I personally respect him very much."
Hong takes with him to Brazil a sizable contingent from the squad which served him so well at the London Olympic games. Korea earned the bronze medal in 2012 and, despite their relative lack of experience, Hong is fiercely loyal to his group.
"We have a young team, they are very energetic, that is true," he said. "But compared to their youth, I think they are wise in their judgement and their decisions. Our players will lead the future of Korean soccer.
"I fully believe in them. I've believed in them from the beginning and I will continue to believe in them. That will not change."