Patent citation counts represent an aspect of patent quality and knowledge flow. Especially, citation data of US patents contain
most valuable pieces of the information among other patents. This paper identifies the factors affecting patent citation counts
using US patents belonging to Korea Institute of Science and Technology (KIST). For patent citation count model, zero-inflated
models are announced to handle the excess zero data. For explanatory factors, research team characteristics, invention-specific
characteristics, and geographical domain related characteristics are suggested. As results, the size of invention and the
degree of dependence upon Japanese technological domain significantly affect patent citation counts of KIST.