This is the 8170th most frequent Japanese word.
山口駐屯地
"Yamaguchi Chūtonchi" refers to "Yamaguchi Garrison," a Japan Ground Self-Defense Force military base located in Yamaguchi Prefecture.
Here, '山口駐屯地' specifies the landmark relative to which the speaker's residence is described.
私は山口駐屯地の近くに住んでいます。
I live near Yamaguchi Garrison.
Here, '山口駐屯地' is used as a proper noun referring to the specific garrison base.
山口駐屯地は山口県にあります。
Yamaguchi Garrison is located in Yamaguchi Prefecture.
In this instance, '山口駐屯地' functions as the location where the activity (training) is taking place.