He served as chairman of the Korean Group of the International Federation of Industrial Property Attorneys (FICPI) and the Licensing Executives Society (LES). He founded the Korean Industrial Property Rights Society and served as its chair for ten years He was an active member of the American Intellectual Property Law Association (AIPLA), the International Trademark Association (INTA), the International Association for the Protection of Intellectual Property (AIPPI), and the Asian Patent Attorneys Association (APAA).

He returned to his alma mater and for several years served as a visiting professor, teaching international intellectual property for the Kyung Hee University School of Law. Also, in the interest of providing a better understanding of Korean intellectual property laws and practice, he published numerous books and law review articles, both in Korea and abroad.

As a tribute to his valuable contributions to Korean intellectual property law and his lifetime achievement in the field, he was bestowed the honor of New Intellectual Patent Attorney by the Korean government in July of 2000.
During his career, Mr. Chang enjoyed a well-deserved reputation as the foremost authority
on Korean intellectual property laws and practice. The following are some of the books and articles he authored to
promote understanding of Korean intellectual property matters.