I listened to the lecture with sincere gratitude that I could learn only such organized and essential knowledge. I listened to the lecture with gratitude again and again because only the essential parts were explained so well that I could understand them. As I studied, the scope was vague and there were many parts that I was not sure about, but I was really grateful that Younghan-nim guided me. I hope you will continue to learn a lot and always be happy, Younghan-nim!!