Have you tried a different browser? I.e., if the error is from Microsoft Edge, have you tried Chrome?
Has anything about your firewall, etc, changed? Do you have a VPN, so that you can temporarily appear to not be connecting from Korea in case there is some strange IP thing going on?
Thanks for reporting that you can log in using a VPN. I'm sure there is nothing intentional directed at Korea... and have asked Graphisoft to follow up on this problem you are having.
As Karl said, we have no intention to exclude South Korea from our API site. Your issue seems to be individual at the moment, so may I ask you to get in touch with our Developer Support team: https://graphisoft.atlassian.net/servicedesk/customer/portals
They will be able to help you fix this.
Customer Engagement Expert, Community Admin
1. It is possible to connect with vpn.
2. Here it is said that the password is wrong.