-ㄴ다던 attaches a remembered claim to the person or thing it was about: 아까 긴장해서 말 못한다던 승민 씨 어디 가셨어요? 'where's Seungmin, the one who said he was too nervous to speak?' It usually carries a raised eyebrow, because the claim and the present reality do not match — FM대로 해야 한다던 국장님이었는데... 'and this was the director who said we had to go by the book.'