South Korea gave up three first-half goals in the loss in Porto Alegre, southeastern Brazil, and the nine-time World Cup participant remains stuck in last place among four nations in the group.
With South Korea's hopes of advancing to the round of 16 flickering, Hong said it was his fault that the team came out on the losing end.
"Our last match (a 1-1 draw with Russia) wasn't too bad, but we couldn't quite build on that performance," he said at the post-match press conference. "The final result is my fault.
Everything that we did during our preparation for the match was done on my direction."
Algeria picked apart the helpless South Korean defense with relative ease, and Hong, a former star defender in his playing days, didn't entirely let his players off the hook.
"Ultimately, we lacked concentration, and we weren't able to respond to the Algerian attack with intelligence," the former South Korean captain said. "We had poor organization, and our players had no communication with each other, especially among midfielders and defenders. I think this must have been a good learning experience."
South Korea has only three days left before taking on Belgium, which already qualified for the knockout stage with a 1-0 win over Russia earlier on Sunday. Marc Wilmots, the Belgian coach, said after that match that he might rest players who have picked up yellow cards and who would miss their round of 16 match if they were booked again.
Hong said his players must put the loss behind them quickly and get ready for the next one.
Hong rejected the notion that South Korea might have underestimated Algeria after the African side lost to Belgium 2-1.
"We've known all along that Algeria was a strong team," Hong said. "We just couldn't do what we were supposed to do."
Vahid Halilhodzic, the winning coach, replaced five players in the starting lineup from the loss to Belgium and the gamble paid huge dividends, as two of the new faces, Islam Slimani and Abdelmoumene Djabou, each had a goal.
The coach said he'd planned all along which particular players would play against South Korea.
"Some players were more effective in training (than others),"
Halilhodzic said. "We used space that the Korean team left. We counterattacked. This is something that we've prepared and rehearsed. We took advantage of the qualities of our players."
This was Algeria's first World Cup win since 1982. Halilhodzic, who has a running feud with the Algerian press over what he alleges has been unfair criticism, said the win was a "great present" to the Algerian people but not necessarily to the press.
"We won, and we scored four goals. Maybe (some journalists) are sad," he said. "It's too bad, but this is how it is. After each match, we'll get better and better. It would be great for Algerian football to reach the knockout stage. It will be complicated, but everything is possible."
While the Algerians celebrated their long-awaited victory, their South Korean counterparts were shell-shocked in the defeat.
Son Heung-min, who scored South Korea's first goal, was reduced to tears after the match. He said his disappointment easily outweighed the joy of getting his first World Cup goal.
"It's not so important that I scored my first World Cup goal,"
the Bayer Leverkusen player said. "We had poor concentration in the early going and made life too easy for Algeria. If we'd played as hard as we did in the second half, Algeria would have had a tougher time."
Midfielder Ki Sung-yueng said he never expected such a big loss on Sunday.
"We did everything we could do in preparation, but we didn't respond to their attack as well as we should have," Ki said. "This was a shocking loss. We never expected the first half to play out like it did."
Defensive back Hong Jeong-ho had a game he'd rather erase from his memory. He and his centerback partner, Kim Young-gwon, were often caught out of position and beat to loose balls by the speedy Algerian attackers.
"Young-gwon and I should have controlled the defense and tried to wake up everyone, but we couldn't do the job," Hong said. "I am disappointed. We tried our best in preparation, but we came up short. Algeria was a strong team."
South Korean captain Koo Ja-cheol, who had the team's second goal, also acknowledged that Algeria had a field day with such a subpar defense.
"The Algerians were able to get behind our defense and made it difficult for us to guard them," Koo said. "They were especially strong on the left side, and we didn't respond to them the way we should have." (Yonhap)