From Yuku Help

Advanced filtering

You can use filtering to manage your members in a far more powerful way than any previous system.

When you use the filters, the resulting members will be those who meet the criteria set by all filters used. For example - using post count: less than 50 and membership: more than 12 months will give you a list of all those members who have been members for longer than 12 months, and have less than 50 posts.