Can I leave and comeback to Korea within my 90 days tourist sticker thing?

Or does re enterring will create a new instance of "application" for the 90 days tourist thing (B1). Basically I have a wedding to attend to next months in USA for a few days. Can I come back as long as my sticker is valid without having to "get a new sticker" ? If it's allowed, what am I supposed to do at the airport? Do I fill the card again, do I show my sticker to the immigration agent? Thanks in advance!