We'll have to find out more about these drummers. They have started showing up at local demonstrations.
The Korean Drummers in question represent the organization, "Young Koreans United" (YKU). The group has thousands of members in 5 chapters including Los Angeles, Seattle, Chicago, New York, and Philadelphia.
The YKU organization was founded in 1984, and at the time it played a central role in defeating the Military Dictatorship that ran Korea. The group continues to promote Peace, Reunification & Disarmament for Korea, and works hard in their local U.S. chapters on issues of social justice.
Next time you see the YKU Drummers... go up to them and say "HI!" They are good people to work with. Visit the YKU Website for more information.