So Dasom has an Internet bully who obviously gets his inspiration from T-ara. This is how I would handle the situation if I was the CEO of Starship Entertainment.
Lawsuits will not work against deranged online bullies. Ignoring them will just cause the issue to get bigger, as the online bully will ramp up his attacks to get more attention. A drastic measure needs to be taken in order to deal with this problem once and for all.
My first step would be to trace the little shit down, which shouldn't be hard given how many cyber detectives there are among Korean netizens. After I find out his information thanks to netizens, I would hire a group of 6'5" 250 lb buff black dudes and send them to this guy's house so the black guys could beat the living shit out of him.
Naturally, this would lead to the online bully telling his side of the story about how he is a victim (getting his inspiration from Japan this time). So, if a dozen black dudes beating the shit out of you doesn't make you stop from harassing someone online, there's only one more way I could think of to make him stop.
I would take a group of reporters from Dispatch and other various news sites along with Dasom to the man's house. We would barge in and some of those big buff black dudes would hold the guy down and strip his clothes off. Dasom would put on a strap-on dildo. Not just any ordinary strap-on dildo, but one with the biggest circumference and length that she could find.
Dasom would proceed to peg the living shit out of him.
Without lube.
And the dude would start crying, and Dasom would use his tears as lube.
All of this would be filmed and distributed over the Internet.
After this, anyone who harassed any Starship idols would face the same treatment. Once they figured out their target idol was coming to peg them without lube, these online bullies would start doing ISIS-style apologies to save their anal virginity.