Cyworld, the Korean social giant that could, finally couldn’t. At least not in U.S. It is shutting down its U.S. service, after three years of trying, according to a notice on its site. It will shut down in entirety on Nov 23. The service, owned by SK Telecom (NYSE: SKM), the biggest telecom firm there, entered U.S. in 2006, and said it would $10 million into launch. The parent company also said a year later it would invest about $110 million in online businesses in U.S., and that hasn’t happened either. Cyworld couldn’t adapt to U.S. audiences, or rather users here couldn’t get used to the cutesy virtual world. Last year the company laid off all its staff and moved the U.S. ops to Korea. Now even that’s going. And times here have changed: when it launched there was lots of talk about competing with MySpace; now MySpace is trying to figure out its own existence.