Um / Yang: Also know as Yin & Yang (Chinese) the symbol represents the duality of nature and the law of opposites. It is used to describe how seemingly opposing forces are bound together, intertwined, and interdependent in the natural world, giving rise to each other in turn. The curved line indicates that in nature there are no absolutes. Lines separating opposing concepts or points of view are rarely sharply defined but are represented more correctly as gradual changes. The effect is a balance of give and take that promotes harmony.
Red (Yang) represents FIRE. In San Kil Tang Soo Do the "fire of discipline" refines our character.
Blue (Um) represents Water. In San Kil Tang Soo Do "nurturing water" improves our fellowship with others.