A graduate student was sentenced to two years in jail for injuring his professor with a homemade bomb in a plastic drink tumbler in early June, a Seoul court said Wednesday.

The 25-year-old mechanical engineering student at Yonsei University in western Seoul has been charged with inflicting injuries resulting from explosives. He built the explosive using a drink tumbler filled with gunpowder and nails and delivered it to the professor's office.

Prosecutors have demanded five years for Kim.  

(Yonhap)

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)