The court said Kim's actions were premeditated, which deserves the verdict, citing the fact that he had placed the tumbler in a gift box with a note that read: "Thank you always."

"The tumbler explosive was dangerous enough to cause serious harm to the life and body of the victim," it said.

The court also mentioned how the defendant tried to hurt the professor before by adding methanol to a water purifier in his office but failed.

But the court said it took into account that he has no prior criminal records and shown remorse, and that the victim is not seeking punishment for him.

The professor suffered only minor burns, as the bomb did not fully detonate. The grad student told police he was angry at the professor for scolding him about his thesis. (Yonhap)