Jeff's mother Yungok Yoon left a great legacy of faith when Jeff was a little. Yungok prayed day and night for Jeff. Jeff truly believes that because of her prayer his faith grew abundantly and stands where it is today. When Jeff joined the military after high school God trained him to become a faithful servant for God's global mission. Jeff served in the Special forces for 7 years in a battalion called the “707 Counter Terror Battalion”. At the end of his enlistment, God called Jeff to leave his comfort zone and go to an unknown land, so he immigrated to New Zealand in 2013. Jeff studied at Eastwest from 2016-2017 and then studied theology at Laidlaw College in Auckland. Jeff enjoys outdoor activities and listening to other people’s stories.

Jeff’s wife, Ginny is also from South Korea but moved to New Zealand when she was 16. Born in a Christian family, Ginny loved singing in the choir and serving in children's ministry. During university she encountered a life-changing moment; the anointing of the Holy Spirit and God's calling to the world of mission. With a burning heart, she started her mission journey through short-term missions to Vanuatu. On her third trip, Ginny met her future husband Jeff in Vanuatu.

Jeff and Ginny are currently serving as missionaries with WEC International. Their passion is to see every nation and tongue to come to know God, and Christ being worshipped, loved, and glorified. They both love music and enjoy journeying and fellowshipping with others.