다고 알다

as far as I know, X

Almost every line here ends in the same shape, meaning I understand it to be so. It flags the information as secondhand and leaves you room to be wrong, which is why it turns up so much in explainer talk: I understand he really exists, I understand that is how the platform screen doors came about, I understand they were third before that. It is politer and safer than stating the fact flat.

Register: careful; explainer talk