There was a press conference held for Taiwanese reporters to promote My Fair Lady in Taiwan. Actually it was more like a Yoon Eun Hye presser than a MFL presser because she was the only one there.
Wow thanks a lot for the explanation. I saw this pic & news at soompi first but I don't get it (at that time) that this was an MFL presscon for Taiwanese since there aren't further explanation. Do you know where was this event happened, in Korea or Taiwan ? And why did the other MFL casts not present ? (sorry for my curiosity) 
Well this post explains more, but this press conference was held in South Korea. The reporters flew in from Taiwan.
It's not so much that the other MFL cast didn't show up, I think it was more of a YEH-focused presscon anyway. She's also a "hallyu" star - a term for Korean celebrities who have high popularity abroad. So she's the best person to promote the drama to a foreign audience. I may be wrong, but I don't think any of the other cast members are well known outside of Korea while YEH is popular in Japan, Taiwan, China, and many other Asian countries.
Also it's pretty much because of her hallyu status, that the drama is even being broadcast in Taiwan.
Yes I agree with you that she's a hallyu star and more popular in another countries comparing with another MFL casts. But the thing is, many people especially fans of the other MFL casts tend to forget this fact and diminished her important role in this drama (and even bashed her acting skill) not just for making this drama had two digit in rating share but also in her role in marketing MFL to other countries. I think they should thanks her instead.
