South Korea's head coach was disappointed with the manner of his team's 4-0 friendly defeat to Ghana on Monday, highlighting the defence as a particular area of concern.
Hong's men have been drawn in Group H in Brazil and will begin their campaign against Russia on Tuesday, before fixtures with Algeria and Belgium.
After overseeing the squad's final training session in Miami before departing for South America, Hong's mood had improved, although he conceded there was still work to be done.
"I am satisfied with how our training has gone in Miami," he told reporters.
"Our players are close to being in top form. They worked on improving their agility, among other things that we didn't do earlier.
"We still have issues on defence. And the defenders aren't the only ones to blame.
"Our offensive players must help out in defence too."
Goalkeeper Jung Sung-ryong, meanwhile, believes the heavy reverse at the hands of Ghana could serve as a useful wake-up call.
"I think we all had a valuable learning experience ahead of the World Cup," he said. "I hope it will help us better prepare for the tournament."
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