Best Answer - Chosen by Voting
in most situations, you don't need to use 당신
for example,
you want to know my name,then just look at me and just say 성함이 어떻게 되십니까?(formal, polite) 이름이 뭐예요?(informal) 이름이 뭐야?(to children),In Korean, a subject can be more easily omitted than in English.
당신의(your) 이름은(name) 무엇입니까(what) is literally changed with Enlish expression into Korean. it's unnatrual.
so,
1. 이름이 뭐예요?
2. 성함이 어떻게 되십니까?
3. 형, 형님, //누나, 누님
4. when you fight with someone, 당신 이름이 뭐야(in angry voice) or when you mention a high postion being ,--오 , 주여 당신의 뜻이라면, 내가 따르겠습니다. oh, my Lord, if it is your intention, I will follow it.)
