중대 출신으로서 중앙대 100주년 기념 행사에 초대 돼서 너무 기뻐요!
As a graduate of Chung-An University, I'm very happy to be invited at the a centenary celebration of Chung-An University!
(‘서’ 맞나요?) means (Is '서' correct?)
The speaker is not sure whether '서' correct or not.
Many Korean people confuse the spelling of 로서 and 로써
로서 is used for position, rank
로써 is used for tool,method
e.g.
그는 의사로서 중국에서 일생을 보냈다.
He had spent his entire life in China as a doctor.
말로써 너의 죄를 고백해라.
Confess your crime to me through word of mouth.