MOO	Pronounced "mu", it can be translated as: military, chivalry, martial. Interestingly, it is the same symbol as you see in the word Wushu, the generic Chinese term for martial arts. If we look at the composition of the symbol, the inner part of the symbol is the word for "stop" and the outer part means "weapon". This character may imply that martial arts are defensive, in that they were designed to "stop weapons".
DUK	We say "deog" in Korean. This word means: benevolence, virtue, goodness, commanding respect, etc. The character on the left means "little steps" or "to happen", and on the right the character means "moral". Combined, these characters imply "moral steps" or "virtuous conduct". We can also break down the word for "moral" to mean "straight" (the part on the top), and "heart" (the four little lines on the bottom). Moral can certainly be seen to come from "straight hearted".
KWAN	This is "gwan" in Korean. It means: mansion, large building, palace or library. The breakdown of this word is quite intuitive, the symbol on the left looks like a house of sorts. And in fact, this part actually means "to eat" - which is something that (generally) happens under a roof.