Apparently it's the 29th(!) annual Korean parade on Oct 3 along 6th ave, with some kind of festival going down in K-Town at the same time. I've never been to this, but sounds like it might be interesting:
"The festival will provide interactive activities, such as Korean cooking lessons from talented chefs from the community, Korean youth singing competitions, and even a Kim Chi making demonstration. Visitors have enjoyed perusing through the various unique products and services available in the product tent, and, of course, savored their favorite Korean food, such as kalbi (BBQ shortribs), bibimbap (mixed rice and vegetables), and kim chi fried rice."
