在朝鮮アメリカ陸軍司令部軍政庁
As a child, Jang learned an esteem for life and calligraphy from his grandfather and Chagang Park, Ki Jung. In 1940, he graduated from Wonju elementary school, and was Christened "John" after being baptized at Won-Dong catholic church. He studied at Henry Appenzeller's Pai Chai Middle School and Pai Chai High School in Seoul. After graduating from high school, he attended Gyeongseong Industrial Technical School (경성공업전문학교) in Seoul, but was expelled for opposing the appointment of John R. Hodge to lead the United States Army Military Government in Korea. At that time he met Choi Je-woo and Choi Shi-hyung, who were major influences on him. In 1946, he entered began studying aesthetics at Seoul National University, but left and returned to his hometown during the Korean War in 1950.