This is the 10772nd most frequent Korean word.
규정하기
"To define" or "to stipulate."
규정하기 is used here to mean 'to define' formally or conceptually.
어떤 현상을 규정하기 위해서는 정확한 분석이 필요하다.
To define a certain phenomenon, accurate analysis is necessary.
규정하기 in this sentence is used in the sense of 'regulating' or 'setting rules for' behavior.
법률은 개인의 행동을 규정하기 위해 존재한다.
Laws exist to regulate individual behavior.
Here, 규정하기 means 'to characterize' or 'classify' something that's abstract or unclear.