From the festival brochure: "Dano or Korean Summer Festival took place on the 5th day of the 5th month of the lunar calendar, the brightest day of the year. Dano was a ritual day spent praying for good harvest and is still observed as one of the principal holidays."
The festival is put on by the Koreatown Business Improvement Association. It has an entertainment tent, a crafts table, and a wrestling area, but otherwise it is entirely devoted to sales (including food and beer), from the many Hyundai cars parked on the grass, through air conditioners and high-tech toilet seats, to cheap shoes and dollar-store merchandise in plastic bins.
When a festival of this nature has a park permit, Permits Department policy prohibits any other activities on the same day that might infringe on the right of the permit holder to sell -- even the giving away of food at a community garden festival would be prohibited, on the grounds that it would compete with food sales.