Why is Kim Hee Sun's name Yoo Eun Soo in "Great Doctor"?

"Great Doctor" deals with the love story between female doctor Yoo Eun Soo and soldier Choi Young (Lee Min Ho).

Choi Young lives during the time of King Gong Min and Princess No Guk. Yoo Eun Soo time warps from the present to this particular point, where King Gong Min returns from Won, the dynasty in China, as he plans to revolutionize Koryo. Many other historical figures like Jo Il Shin, Duk Heung and many others appear in the story. It does add fiction to the history but these are many names that the viewers are familiar with. 

At this point, Yoo Eun Soo's name is getting the attention of the viewers. By the time Choi Young becomes general, his second wife's last name was Yoo. It could just be a coincidence but there are stories about how he really loved his second wife Yoo. There isn't much about his second wife in history so it's fully possible that people added their imagination to it. 

In "Great Doctor," the story emphasizes that Yoo Eun Soo didn't just end up in Koryo for no reason. Will she actually meet a happy ending in Koryo, next to Choi Young?

On the Tuesday episode, Yoo Eun Soo actually recovers her diary. She finds phrases that indicate her future like, "That day, you're going to go far. That night, someone will come find you. Don't refuse his request. You have to go back, only then will he live." "That day, you can't let him go. What was waiting for him that day was a trap." Is it that she went through the time warp multiple times in order to save him?