You will need a MBC account to vote for INFINITE on Music Core. This account is different from MBC Show Champion.
Voting Period: Wednesday 10am KST – Thursday 12pm KST
NOTE: You can vote 4 songs per ID.
How to create a MBC account
1. Go to MBC official site and click ‘회원가입’,
2. Choose the ‘Domestic & Foreigner Living in Abroad’.
3. Tick all the boxes and click next.
6. Fill in all the needed details. Then click confirm.
9. Go to Music Core Official Voting Site to start voting.
10. You are allowed to vote 4 songs per ID so make sure to vote for INFINITE and 3 other songs. Tick the box of your votes. Then scroll down until the bottom and click the button to send your votes.
(cr. @gyuyomizizi of Infinite_Biased)