Joo and Shin voted for a smaller hike in the rate, Rhee said in news conference, but did not elaborate on their views.
Twenty-three of 26 analysts expected the bank to go for a half-point hike in a Reuters poll, while the remaining three expected a quarter-point hike.
The median forecast in the poll showed the BOK's base rate going to 3.25% by year-end and then peaking at 3.50% in the first quarter of 2023.
Almost half of respondents in the Reuters poll expected the base rate to reaching 3.75% in the first quarter of next year.
After Wednesday's rate hike, the Korea Federation of Small- to Medium-sized Enterprises expressed "serious concern" about higher rates.