Koeun began learning piano at the age of ten in Korea. After immigrating to New Zealand in 1977, she continued her piano studies under the guidance of Sharleen Penman. Koeun achieved Grade 8 Solo Piano with Distinction through Trinity College London and obtained a Performer's Certificate in Solo Piano. She has extensive experience as an accompanist, serving for many years in churches and with New Zealand missionary groups. She currently serves as an organist and pianist at Greyfriars Church.

In addition to her performance experience, Koeun has many years of teaching experience in music schools in Korea. She has also completed teacher training in the Piano Adventures programme through Edu Primo.

Koeun completed a Diploma in Music at the University of Auckland, studying under Dr Sarah Watkins. She is currently preparing for her FRSM and ABRSM Diploma qualifications in Pipe Organ Performance and Music Teaching.