Could you enlighten me as to what 'chun in steps' are?
A chun jin step is a sliding step forward without changing your stance (same foot remains in front). You can do it three basic ways. First way, the beginning way, is to slide your back foot up to your front foot, then slide your front foot forward. Second way is to slide your front foot up and then drag the back foot up. The third way is to slide both feet at the same time.
A who jin step is the same basic thing, except you are moving backwards.
The steps were introduced into Taekwondo competition by Jidokwan GM LEE Byung Ro, who was a student under GM CHUN Sang Sup and was later an instructor at the Han Guk Che Yuk Kwan with GM LEE Chong Woo. GM Chun had these series of drills based on stepping and kicking with roundhouse. GM LEE Byung Ro died early, I want to say in 1982, and he was the first actual Taekwondo practitioner to receive the Kukkiwon 10th Dan. His best friend was Han Moo Kwan founder GM LEE Kyo Yun, who he studied with under GM CHUN Sang Sup.