Hi Miyeon,
The Ethics credits are included in the overall requirement. Here is an excerpt from the irs.gov ERPA CE Q&A:
"3. I enrolled in year 3 of an enrollment cycle in the month of November and my social security number ends with a five (5). How many CPE credits must I complete? You are required to complete four (4) CE credits for November and December of the 3rd year; of which two (2) must be completed in Ethics courses. Your next renewal cycle 2011-2014 you will be required to complete a minimum of 72-hours of continuing education credits which encompasses three (3) calendar years. (Note: a minimum of 16 hours of continuing education credits, of which 2 credits must be on ethics, must be completed during each enrollment year of an enrollment cycle.)"
Regards,
Jim