太極旗 the national flag of Korea, the Tai-geuk flag
The Korean flag is called Taegukgi. Its design symbolizes
the principles of yin and yang in Oriental philosophy.
The circle in the center of the flag is divided into two equal
parts. The upper red section represents the positive cosmic forces
of yang. Conversely, the lower blue section represents the negative
cosmic forces of yin. The two forces together embody the concepts of continual
movement and balance and harmony that characterize the sphere
of infinity. The circle is surrounded by four trigrams in each
corner. Each trigram symbolizes one of the four universal elements:
heaven, earth, fire, and water.