CS Happy Entertainment has revealed that December's Yoon Hyuk got into a serious car accident on February 4th while driving with his friends after recording December's new single. CS Happy Entertainment stated:

The car flipped and Yoon Hyuk suffered an 8cm laceration to this head. His nose, ribs and pelvic bones were all cracked as well. Yoon Hyuk was sent to the hospital and was hospitalized for six weeks.... his friend who was the driver broke both legs and another friend who was in the car broke his waist. When the car flipped, the car was on fire. Yet Yoon Hyuk, struggling through his injury, saved his friends. His courageous action which helped saved lives surprised us all.  Because he was seriously injured, we were going to postphone December's new single release date, but because Yoon Hyuk was so determined to let his friends and fans hear the new single, we decided to proceed as scheduled.