그렇군, 맞아, 그랬군

[세이지]

그렇군요.
"(I know that what you are saying is) right."
or "(I hear you saying it)"

You are agreeing with people or you are confirm‎‎‎‎ing that you understood the other party.

A: 이 강아지의 이름은 미미에요. (this dog's name is Mimi.)
B: 그렇군요. (it is.)


그랬군요.
"(so, )That was it"
or "(I hear you saying that)"

You are confirm‎‎‎‎ing that you understood the sentence the other party gave you. And that statement is in the past.

A: 어제는 많이 아팠어요. (I was very sick yesterday)
B: 그랬군요. (you were.)