Finally, I finished it. Before listening to this, I listened to the Spring introduction that was distributed for free and didn't understand it, so I listened to it twice. Somehow, after completing it and listening to this, I understood it easily. What I liked the most was the quality of the lectures, but I think it was the QnA service. I will be able to trust and use Professor Kim Young-han's lectures and the Infraon service in the future. Thank you.