Hamilton could only finish 10th at Yeongam, and was informed by his McLaren team after the race that his car had broken a rear anti-roll bar near the end of the first stint.
The result leaves him 62 points behind race winner and new championship leader Sebastian Vettel with four rounds to go.
"I think in terms of winning [the title], I think that's it for us," Hamilton conceded.
He added: "I guess the pressure is now off. It's tough because there's been so much work from the team and myself to win this thing. It's too far away now, but we'll keep fighting to try and get as high as we can in the constructors', and I hope me and Jenson [Button] can have some stronger races in the next ones.
"We've had three failures in the last three races on my side of the garage. I hope my luck changes."
Hamilton ran fourth at first, before being overtaken by Felipe Massa and Kimi Raikkonen as his suspension problem slowed his pace.
The issue also affected tyre wear, forcing him to switch to a three-stop strategy and lose further places.
"It wasn't particularly fun going backwards," said Hamilton.
"A McLaren should never be fighting with a Toro Rosso. A McLaren should never be fighting with a Force India.
"But I put up as strong a fight as I could without colliding."
Hamilton's car also picked up a large piece of stray astroturf near the end.
"It just added on to where my car was going anyway," said Hamilton of the debris. "I'm lucky that I was able to at least hold on and keep 10th."
While downcast about his championship situation, Hamilton said he was proud of himself for how he had coped with the car problems.
"It's really sad that we're pretty much out of the championship, but sometimes these races show the true spirit within," he said.
"I feel quite comfortable with myself that I pushed and gave it everything."