In ancient Korea, the traditional Um/Yang symbol had three distinct sections instead of two: heaven, earth and human. These people deduced that whenever two forces opposed one another one of two things would happen: one force would dominate the other, thus one would be superior and the other inferior; or the two forces would be equal, becoming neutral. They examined how the forces of Um and Yang impacted Humanity. This is the essence of I Ching.
Everything around us has an opposite: hot and cold, high and low, summer and winter, fire and water. Um energy is soft, yielding and passive. Yang is hard, aggressive and active. Striking a balance between Um and Yang energies would result in Tae Guk or Grand Ultimate. Tae Guk is a state of neutrality where perfect harmony exists. Energies naturally flow from yang to um and back to yang effortlessly. Neither force dominates the other.