In soompi there's an article titled;
“Bridal Mask” Production Team Not Happy With Jin Se Yeon’s Decision To Join “Five Fingers”:
"In the middle of the shocking decision to choose currently airing KBS Wednesday-Thursday drama “Bridal Mask” female lead Jin Se Yeon, who is still shooting for the drama, over T-ara member Eunjung for the female lead role in drama “Five Fingers,” it has come out that KBS is not happy with such a decision and cannot understand such a decision.
On August 23, “Bridal Mask” drama producer Lee Geon Jun said that, “It is ridiculous and unheard of for a mini-series drama female lead, while the drama is still broadcasting, to be splitting her time appearing in another drama.”
The “Bridal Mask” drama production’s concern is that as the two dramas’ shooting schedules overlap, at a critical point in shooting, the busy drama “Bridal Mask” might suffer some harm."
Having two drama shooting at once in Korea seems a handful, I don't want to see this as apersonal greed in Se Yeon, but I guess Se Yeon's agency is an ambitious one. I hope this new star won't become another victim of K-entertainment like our Eunjung >.<.