Doctor Ezra Hangjun Jang is a naturalized Korean American physician, President of the youtube channel, Dr. Ezra Hangjun Jang TV, and CEO who works at Ezra Medical Care PC, Harlem Firstaid Medical PC, and Riverside Health Care LLC.

Dr. Jang was born in Seoul, South Korea. After graduating from Hanyang University School of Medicine, Seoul, South Korea, in 1996, after three years of military duty, he came to the United States with his American wife. Dr. Jang enrolled in chemistry graduate school of New York University (NYU) in 2002. In his third year of graduate study at NYU, he started as a medical resident in Brookdale University Hospital, Brooklyn, in 2005. Since then, Dr. Jang has pursued MD, Ph.D. dual degree track. He successfully defended his Ph.D. thesis on August 31, 2007, under the mentoring of Kent Kirshenbaum. During the graduate study, Dr. Jang published three articles in peer-reviewed journals, and his study focused on the functionalization of a peptidomimetic scaffold. He was a first-person who first successfully conjugated nucleobase into a peptidomimetic scaffold peptoid using azide-alkyne cycloaddition reactions. Dr. Jang published as the first author of this work in Organic Letters (Org. Lett. 2005, 7, 10, 1951-1954). He also was a recipient of the Golden Dozen Teaching Award in NYU’s College of Arts and Science in 2004. Dr. Jang graduated with a Ph.D. in chemistry from NYU on May 14, 2008. After completing a three-year residency in Brookdale, he became a board-certified internist and a physician in New York in 2009. Dr. Jang had served New York Hospital Queens as a primary care physician in the ambulatory care clinic at 39th ave, Flushing, NY 2009 through 2011. He incorporated his medical organization – Harlem Firstaid Medical PC, Ezra Medical Care PC at 15009 Northern Blvd, Flushing, NY in 2012. He also formed Riverside Health Care LLC in 115 Broad Ave, Palisades Park, NJ, in April 2021.

Dr. John Yoo was born in South Korea and immigrated to the US at age 4 with his parents and older brother. 5 years later, at age 9, John and his family were scheduled to move back to Korea to follow their father's job location, but a young Dr. Yoo and his brother insisted they would study in the US instead. Their parents took a leap of faith and embarked on what would become a 10 year "gireogi" status with their father working overseas, and their mother looking after the kids in the US. Vowing to make their parents' immense sacrifice worthwhile, both brothers promised each other to work their hardest to make their dreams come true.

Dr. Yoo's brother (Dr. Eric Yoo) went on to match to his dream medical specialty in Gastroenterology, but Dr. Yoo debated whether to go into medicine, dentistry, or... K-Pop. After much deliberation, he decided to pursue his studies and combine both his love for the arts with healthcare, and found dentistry to be the healthy intersection of all his interests. At Columbia Dental, he received the Outstanding Student Leader Award from the American College of Dentists for exceptional leadership, scholarship, and service commitment to his community. From college to his pediatric dental residency training at Jacobi Medical Center, Dr. Yoo tutored students from around the world through an online classroom, and discovered a passion and knack for working specifically with the pediatric population. His videos on pediatric patient management and strategies have garnered him recent internet fame, amassing over 150 million views across platforms.

Dr. Yoo has been featured on numerous social media channels and has lectured to students on topics ranging from pediatric behavior management, dental school and applications, dental residency, and social media. After graduating from residency, Dr. Yoo teamed up with Columbia colleagues to build Beam City Dental Pediatric Dentistry & Orthodontics in Fort Lee, NJ, where he now works as a full-time pediatric dentist and co-owner.

Dr. Yoo has been involved in numerous Korean organizations including Korean American Scientists and Engineers Association, Korean American Students Association (Former Duke Chapter Founder/President), and Korean American Dental Students Association (Former Columbia President). During his downtime, Dr. Yoo enjoys making YouTube videos with his best friend on channel JBRO, working out, golfing, traveling, personal training, and singing. Dr. Yoo has participated in dental missions to Brazil, Peru, Panama, Jamaica, and Cambodia, and is eager to treat more children around the world along the way.