In 1955, the Moo Duk Kwan Central Gymnasium was opened near Seoul Station in Joong Gu's Dong Ja Dong, Seoul. In the same year, 9 more annex schools were opened and it held the friendly China-Korea International Tangsoodo Championships.
Hwang claimed Gogen Yamaguchi, the founder of Japanese Goju-ryu, as a personal friend. In 1939, Yamaguchi, nicknamed "the cat," was in Manchuria as a Japanese intelligence officer stationed near the Russian border and Hwang's travels took him near the border. From an examination of his later writings, Hwang certainly seems to have been much more influenced by Japanese Karate-do than by Chinese Kuo-shu. The basic pumsae (forms) of Tang-soo-do are nearly identical to the kata (forms) of Shotokan karate. They include the three kijo pumsae (based on the three taikyokyu kata), the five pyong-ann pumsae (based upon the five heian kata), and "basahee" (bassai). On the other hand, the advanced pumsae are named after Chinese styles, including T'aigukkwon ("great absolute fist" ( Taijiquan) and Jangkwon ("long fist").
In 1953, Tang-soo-do Moo-duk-kwan began to evolve. It changed its official title to the Korea Soo Bahk Do Association. By 1955, this organization had ten gymnasiums with its central headquarters near Seoul Station in the Jong Gu section of Dong Ja Dong. During this same year, the Moo Duk Kwan Central Gymnasium was opened near Seoul Station in Seoul and the it held the China-Korea International Tang Soo Do Championships.