Some of the statements made in this thread regarding KKW TKD are rather misleading.
The KKW testing requirements specify self defence as one the 5 disciplines required to be demonstrated (the others being sport sparring, breaking, step sparring, and poomsae).
What's specifically within that SD bracket varies greatly with location, school, and individual instructor experience.
At most of the schools I've been part of, grappling has been on the SD agenda in some form, often with hapkido and yudo techniques incorporated, and including some degree of ground work (usually with the defender remaining standing, but not always).
This is particularly true with the Yong In alumni, as there's a strong current of military / security service / yudo accompanying their Taekwondo practice.
So, is grappling specifically on the syllabus? No. But self defence is, and it's hard to practice Taekwondo self defence in any reasonable way with any reasonably experienced trainer and not learn some level of grappling skill.
I spend quite a significant proportion of my training time being thrown or grappled to the ground and doing the same to others, within the KKW framework.
Gnarlie