Is ~는데 a contraction of 그런데?
I watched a video where a native Korean speaker who teach Korean on a website, explained how to say the sentence "I understood, and/but still I'm thinking" in Korean.
He firstly wrote "알아들었어요. 그런데 생각하고 있어요", and immediately after that, he told that sentence (wich is made by 2 clauses), could be convined or shortened like this:
"알아들었는데 생각하고 있어요"
So, my question is, is ~는데 a shortened form of the word 그런데? Are these 2 used for the same kind of sentences and mean the same?
Thank you so much for your answers! :)