Source: The Korea Herald/Asia News NetworkThe announcement of Sistar19's comeback in January has sparked news of other spin-off groups who wish to make a name for themselves this year. Girl group 4minute and the new boys of Infinite have both confirmed that they will be launching sub-groups of their own.Early last year, one of the leading girl groups in the K-pop world, Girls' Generation, found success with their own spin-off group, Girls' Generation-TTS, also known as TaeTiSeo, with members Taeyeon, Tiffany and Seohyun. Now, with the announcement of more of these groups looking to hit the stage, it seems as though this year will see the birth of many other sub-groups.The duo of Hyo-rin and Bo-ra who comprise Sistar19, a spin-off of sexy four-member K-pop group Sistar, first debuted in 2011 with their single "Ma Boy." However, Sistar19 has not been active since then and the members have just been promoting themselves within the main group Sistar.After the news of the unit group's comeback to the music scene, 4minute and Infinite both announced the debut of their spin-off groups last month.Heo Ga-yoon and Jeon Ji-yoon of the five-member girl group 4minute will comprise the group's first sub-group, which is currently being referred to as "Double Yoon." Representatives of Cube Entertainment revealed that the two would be debuting after the release of 4minute's next album. The representatives also stated that they would be promoted as a ballad duo.The ladies of 4minute debuted in 2009 with their dance track "Hot Issue" and have since made a name for themselves as one of the leading girl groups in the Korean entertainment industry. However, the members have had quite a shadow cast over them by the solo career of Hyun-a, who has become the face of the group. With the vocal skills of Heo and Jeon, the duo hopes to differentiate themselves as a ballad group.The seven-member super rookie idol group Infinite has also revealed the creation of a spin-off group, called Infinite H, with members Dong-woo and Ho-ya. Infinite debuted in 2010 with the single, "Before the Dawn," and have since released more than 10 albums and amassed one of the largest K-pop fan followings. The two hope to establish themselves as a hip-hop duo with the help of music producer Primary. Infinite H is scheduled to release debut single "Fly High" later this month.