The Sam-ak  [3 Sacred Peaks]
the Korean-style Sam-Taegeuk
[three-part Grand Ultimate] Symbol,
used in Korean Shamanism, Neo-Confucianism, Daoism and Buddhism

Blue = Heaven    Red = Earth    Yellow = Humanity
Heaven influences Earth, which influences Humanity, which influences Heaven...

or, in other interpretations, Blue = Heaven, Yellow = Earth and Red = Humanity
(depending whether Red is seen as the color of Chinese farming-soil or of human blood, and Yellow is seen as the color
of soil or of human skin; the Chinese Emperor wore yellow robes in representing Humanity as the "Son of Heaven".)
The Korean Sam-Taegeuk symbol above is
related to but quite different from the better-
known Chinese
Yin-Yang 陰陽 yīnyáng 阴阳 symbol
(right), also called the
Taijitu 太極圖 Taìjí tú 太极图 or
T'ai-chi, literally "Diagram of the Supreme
Ultimate", most frequently used in Chinese Taoist
and Neo-Confucian philosophy and cultural arts.
Stained-glass-mosaic window in the Hyehwa Catholic Church in Seoul