Hi @Jun-Hwan, and welcome to the Samsung Community forum. 👋
If you do not see the option to join the beta in the Samsung Members app, this means that your phone may not meet the eligibility criteria. There are a number of reasons for this, but the main one is whether you purchased your phone directly from Samsung or your network provider.
If you purchased from your network provider then the software installed on your phone by them is not currently compatible with the beta software, which means they are currently not participating in this program.
As One UI 7 is currently undergoing beta testing, we expect that the finished and polished version will be with you as soon as possible.
I'd recommend keeping an eye on our Newsroom for any further updates.
