Song Jie-un

In April 2017, Song starred in OCN's romantic comedy drama My Secret Romance alongside Sung Hoon.

In August 2017, Song submitted a request to the Korean Commercial Arbitration Board to verify that her contract is no longer valid due to TS Entertainment not following the terms of the contract. Song later took to her Instagram where she announced her departure from Secret.

In September 2016, Song released her second extended play, titled Bobby Doll containing six tracks, including the title track of the same name.

In April 2015, Song featured in fantasy youth comedy The Superman Age, an 8 episode series which aired on cable channel tvN. She then starred in the web drama The Immutable Law of First Love, based on a web novel of the same name, playing a photographer who loves abandoned dogs. In November, she starred in KBS's daily drama Sweet Home, Sweet Honey and received positive reception on her performance.

In 2014, Song released her first extended play, titled 25, which contained two singles "Don't Look At Me Like That" and "Pretty Age 25". The same year, Song made her acting debut in the web drama Drawing, Spring, as a part-time worker for a PR team, who loves all living things but has traumatic experience with horses.

In 2013, Song released her first single album Hope Torture, which she unveiled at her album showcase at the Olleh Square in Gwanghwamun.

After Secret's success with "Shy Boy", TS Entertainment announced that Song will make her solo comeback with the song "Going Crazy". The song was dubbed as an "emotional ballad track" and "different to what she's shown through Secret". The single, released in March 2011, was a success and peaked at number one on Gaon Singles Chart, making it Song's and Bang's first number one single in Korea.

In September 2009, TS Entertainment announced that they will be debuting a four-member girl group in October 2009. Song, along with Han Sunhwa, Jung Hana and Jun Hyoseong, debuted as the group, Secret. Prior to their debut, the group was on a documentary show called "Secret Story" which chronicled their debut process. They released their debut single "I Want You Back" in October 2009.

In December 2009, she sang a duet with Hwanhee titled, "Yesterday".

Song Ji-eun, (born May 5, 1990), better known mononymously as Jieun, is a South Korean singer best known as a member of the South Korean girl group Secret. Aside from her group's activities, she has released several solo songs and participated in various OSTs. In 2011, her second single, "Going Crazy" featuring Bang Yong-guk, went to become her first number one single on the Gaon Chart as a solo artist.

Song Ji-eun was born on May 5, 1990, in South Korea, she is an only child. Having interest in music when she was young, she auditioned for JYP Entertainment at an early age. While in JYP Entertainment, she sang OSTs of Korean dramas in 2007 and 2008 such as "Learning To Fly" for Air City. Under JYP Entertainment, she was set off to debut as a four-member girl group with Sistar's Hyorin, BESTie's Uji and EXID's Hani, but the plan was scrapped and Ji-eun then left JYP Entertainment and joined TS Entertainment.