YMAA Retreat Center Dr. Yang, Jwing-Ming's Retreat Center web site in California. Information on the center, seminars, progress of the students, etc. can be found here. YMAA - Yang's Martial Arts Association Dr. Yang, Jwing-Ming's web site. Information on his school, seminars, and products can be found here. World Tai Chi and QiGong Day Official site for World Tai Chi Day. Also contains information on tai chi and qigong schools and locations as well as general knowledge about tai chi and qigong.