Great Question! So "Tahn-jeon" is actually spelt as 탄전 in korean which comes from the chinese characters 彈戰. 탄彈 meaning "flick or extend outwards (usually with hands)" while 전戰 means "battle or fight". Korean words derived from Chinese do not always reflect the exact meanings but reather a general concept and then is adapted for their need, such as "slow pushing" in the case of Taekwondo. In english for example, we have the word, "capital punishment" which means the death penalty. However, capital has a meaning of "head, main, partial, or chapter". In this context capital punishment makes no sense but we all know the word for its used meaning. Bahn-son is actually 반선 is represented by the characters 返禪 which mean to turn around and ZEN. Following the same logic we can extrapolate the intended meaning that when we turn from the world and give our hearts to reflection of the past behind us through the Chinese concept of zen or 禪, that I believe most of us are familiar with, then we are meditating. Most koreans use 명상 for meditation but I hope that helps you understand a bit!