What is "uisun"

Cho-ui Seonsa (1786–1866) is often called "The Saint of Korean Tea" or the "Father of Korean Tea". He was a Korean Buddhist Seon ( Zen) Master who in the first half of the 19th century introduced the Way of Tea ( tea ceremony) and the practices of Buddhism to many aristocratic scholars who were dissatisfied with the rigid neo-Confucianism of the Joseon era. He was himself noted as a calligrapher and artist, as well as a poet, and he formed deep friendships with other famous figures of his time, especially Jeong Yak-yong and Kim Jeong-hui.