My savings matured: should I put it in a deposit or bonds?

My 3-year installment savings of 12 million won matures next week. Interest rates are in a weird spot right now, so I'm trying to decide where to put it.

I already invest in stocks, so I want to keep this in safe assets, but bank deposit rates are too low, and I've never bought bonds before, so I don't even know how to buy them. If I won't need the money for 3 years, is a deposit just the answer?