Interpretation of second character
It looks like it is indeed 丁. The Flickr link mentioned the photo was taken at 茶山草堂. With that information, I was able to find another site with a photo of the same doorway indicating that it says 寶丁山房.

I don't know the specific reason why the character is stylized in this way, though 茶山 refers to the pen name of Joeng Yak-yong (丁若鏞), so it could be in reference to his surname, 丁.