This might be her. Same name, same age... She looks young.
Shin Hye-jeong, better known mononymously as Hyejeong, is a South Korean singer and actress. She is best known as a member of the South Korean girl group AOA.
https://en.m.wikipedia.org/wiki/Shin_Hye-jeong
No, that’s not her. I seriously doubt a successful kdrama actress is giving up her lucrative career to become a high school freshman.