What's the correct grammar for using noona, hyung, unnie, oppa, and dongsaeng? Like, would 당신 say their name? Ex: "Hoseok-oppa?" Is there a term for extreme respect 또는 something?

I'm trying to write a story where this guy acknowledges a younger girl, and she 답변 back (this is a work environment, they aren't really close). How would I write that respectfully?