by In-seong Hwang
This collection focuses on tsumego problems that occur in very common positions. Reading out these life and death situations can be very difficult, but should be part of your knowledge, as these problems happen very often in actual games. The second part is from a lecture that shows you how to win capturing races.
The origin of these problems are the lectures of In-seong Hwang's online go school, called Yunguseng Dojang, that you can find here: eyd.yunguseng.com.
The system is called Yunguseng for two reasons: It's based on the real Korean Yunguseng system and they study Go as seriously as the Korean Yunguseng. The Yunguseng Dojang is highly recommendable. All your games will be reviewed by In-seong through recorded video. The lectures are recorded too, so you can watch them whenever and as often you want. Further, Yunguseng has an own rating system, it will show your improvement each month. Also, the system will make you apply the lecture topics in your games.