I'd never heard about this until yesterday, when one of my 21-year-old students told me that the third Monday of May, for all the nation's 21-year-olds, is their formal "coming of age" day.
She said she was traditionally supposed to receive flowers, perfume, and a kiss on this day. Very interesting -- I didn't know anything about this.
Then today, at An Acorn in the Dog's Food, actually gives an explanation, with photos, of the ancient Korean coming-of-age ceremony, which involves hanbok, wine for men and tea for women. Thanks, buddy!