What is Kang? Generally Kang means "hardness". The hard are stone
or steel. The essence of its property is that it doesn't lose its shape yet
rather forces a change to its opponent. When stone or steel were to be struck
by something else it doesn't change yet rather force a change, breaking it.
This is what Kang implies, i.e. hardness.
What is Kang in Taekwondo then? Its meaning is not different either in Taekwondo.
The intentional meaning of concept of Kang is "to do what you want to do
against what your opponent wants to do or to change". Its essential point
can be summed up by a word, "concentration". And it is the extensional
meaning of the concept of Kang.
A hard stone or steel can be so hard as its granules are assembled by high
density. That is, the concentration can produce hardness. This is what the essence
of Kang tell us. This concentration is one of the most basic principles for
all kinds of battles or fights.
How to get this Kang? First, you should practice Taekwondo poses to place everything
of yours on its own proper position all the way along the way of Haneul. And
you can get this concentration from the spacio-temporal coincidence in its completion.
This reconciled motion “goes together
with all the others at once, thus even though the motion needs only a little
room its power can be so strong as that of your rushing from a long distance.
Since the motion is in accord with the change of everything you can produce
the power of heavy mountain even if you were light, and since the way of its
movement includes spinning and returning in one its attacking power is sharp
and hard like the edge of a massive sword even if it moved slow and tender.”(Ch.36)
It means no difference from the hardness of stone and steel.