Dr. Hong-Kyun Yoon serves as the director of Hong-Kyun Yoon Psychiatry Clinic. A graduate of Chung-Ang University College of Medicine, he is renowned for his expertise in self-esteem and addiction. Raised in a large family of 10, Dr. Yoon's early exposure to interpersonal dynamics sparked his interest in behavioral psychology. A journey that started with a dream to become a writer led him to discover the intersection of psychology and science, ultimately becoming a psychiatrist and an author. The Self-Esteem Class is a culmination of his experiences and knowledge, aimed at addressing the concerns and questions of those seeking to better understand and transform their lives. It has quickly become a publishing phenomenon in Asia, with sales exceeding 1.1 million copies.