This is a portrait of the mountain deity (sansin), found in one of the smaller halls. There are actually many mountain deities in Korea, but there is one iconic representation that stands for all of these deities. He is usually depicted as an old man attended by a tiger. I think the one representative is a specific mountain deity, but I’m not sure which one (I want to say Kim Yusin, but I can’t say that with any certainty). Perhaps someone with more knowledge of Korean art will drop me a line.