Complex sentence: Over the years, the "Chosun Ilbo" company also published many additional titles, including a monthly current affairs magazine, "Youth Chosun", the first of its kind in Korea.
Split into simpler sentences: Over the years, the "Chosun Ilbo" also started to publish many side publications. One of these was a monthly publication of current events called "Youth Chosun", the first of its kind in Korea.