Conversation so far:
What was the line up changes Kara (South Korean band) faced?
member Kim Sung-hee suddenly announced that she would be leaving the group.
Why did she leave the group?
parental pressure because her participation in the group was contingent on the maintenance of her grades.
Who was she replaced with?
DSP stated that the second album that was recorded would be shelved and replaced by a mini-album to come in May; in addition, two members would join the group.
What were the names of the two new members?
Auditions were held, and the two new members were eventually revealed to be Goo Ha-ra and Kang Jiyoung.

Question: What is "Rock U"?
Self-contained rewrite: What is Rock U?