Daniel was born in Korea but immigrated with his family to the United States when he was just two years old. His hometown is Easton, Pennsylvania. He speaks English with no accent, though most people wouldn't guess it from his performance on Lost.
Daniel earned a Bachelor of Arts degree from Haverford College/Bryn Mawr College in Theater & Political Science. During that time, he spent a semester studying at the National Theater Institute at the Eugene O'Neill Theater Center in Waterford. In 1993, he started the MFA acting program at NYU's Tisch School of the Arts and graduated with a Masters in Acting in 96.
Daniel's first major role was as a very young Torvald in Pan Asian Repertory Theater's presentation of Ibsen's c play, "A Doll's House." He has had numerous theater roles which comprise the bulk of his early acting career.
Daniel currently lives in Hawaii. He is married, with two sons.