Can you tell me which name is the family name..

[MamaToABeautifulBoy]

Won Joon Jang

I have to send an official email to this person (South Korea based, if that helps).

Thank you 🙏🏼

If in Korea, surname first (Won)

If living in the West, some people take the Western tradition of surname last.

Jang is a very common surname, Won is less common but still could be the surname. Do they have their name in Korean anywhere? That will make it clearer - if the first character is 원, the surname is Won.

Looking online both Won and Jang could be surnames although Jang is a much more common surname than Won with Won being quite a common given name.

I would guess that this person is Mr Jang. But if it's important you get it right you could hedge your bets and type out the full name Mr Won Joon Jang.

Won-joon is also a far more common name than Joon-jang, which I'm not sure is actually a name.