The goal of this study is to investigate the relationship between a bound noun `keos` and its prior & posterior elements in the `21st Century Sejong Corpus` in order that we may study the collocation of the bound noun `keos`. Accordingly, we first studied the collocation of suffixes and case markers of the bound noun `keos` as its prior & posterior elements. Then, we researched the verbs co-occurring with the bound noun and its posterior forms combined with case markers, through a frequency analysis of the posterior elements. In addition, we tried to figure out how well the description of the bound noun in a dictionary has been made in terms of its collocation. We compiled a usage index, using `NLPTools`, based on the `21st Century Sejong Corpus` and studied the collocation of the bound noun, using `t-score` & `MI-score`. As a result, we fond that the prefixes such as `ha-` and `toy-` and the suffixes such as `i-` and `kath-` made a collocation with the bound noun `keos`. However, those combinational structures of the bound noun and case markers such as `keosita`, `keoseun`, `keosi` showed a relatively high frequency rate, and so did those verbs co-occurring with these structures as in `anita` and `sasilita`. In conclusion, we could posit that the bound noun `keos` and its prior & posterior elements may be formed together to make idiomatic phrases.