When dojunim Kim Yun-sang was teaching a seminar in Wittenberg, Germany, I went there together with Frans van Drenth, his brother and some of their students. So yes I do know him but we have only met once.
Frans stopped teaching hapkiyusul however and switched to aikido instead.
The principles that guide hapkiyusul and hankido have many similarities. Actually many martial arts like aikido, hapkido, hapkiyusul, daitoryu, hankido and hjms share the same core principles. However their emphasis on certain aspects may differ and with that their techniques may look different. When I was at the seminar with dojunim Kim I found that we share a lot of ideas about the use of power in techniques etc.
This does not only happen between different martial arts, it also happens between practitioners of the same martial art. Since we are all different individuals we use the techniques of a martial art in our own way. As a student you first learn a basic way (your teacher's way) to do the technique, but later you will adapt them to your own style. Again, this doesn't mean that everybody should start his own martial arts style, but when you see differences between several high ranking masters of one style, it is because they have different body types. In the end it doesn't really matter (to me) how the technique looks from the outside. It is the inside of the martial art, its core principles that are important. If the core is okay, the outside will be okay as well.
If you don't build a strong core, in the end your techniques will always suck
![nii-in ;)](./images/smilies/smile_wink.gif)
(pardon my language).