Kim Changhyun (김창현) is a South Korean jazz double bassist and composer, billed on streaming services as Kim Chang Hyun and in some credits as Chang Hyun Kim. He first won notice in 2005 and 2006 as the bassist of the guitar trio Triologue, whose debut album Speak Low took two prizes at the third Korean Music Awards, and again on February 26, 2015, when his EP Oblivion (망각) won the Best Jazz & Crossover Performance award at the 12th Korean Music Awards. Between Reverberation (2012) and Independency of Wave (2024) he has released ten records under his own name, and the leader records are largely improvised. Korean sources describe him as a professor in the department of living music at Dankook University.

Very little has been published about his early life. No source gives his birth year or birthplace, and no interview in which he talks about his upbringing or his teachers was found. The one account of his training is the artist profile printed with the release of Reverberation in 2012, which lists Berklee College of Music (performance) and Indiana University (jazz studies) without dates, and describes him as a professor in Dankook University's department of living music. A 2015 notice in the Kyunghyang Shinmun adds that the magazine Jazz People named him the best bassist of 2010. His documented career in Korea begins in 2005 with the trio below.

The earliest record is Speak Low, issued on April 22, 2005 by Triologue (트리오로그, also written 트리올로그 and TrioLogue): the guitarist Kim Min-seok, Kim Changhyun on bass and the drummer Oh Jong-dae. Its Korean release text calls it one of the most accomplished debut albums by a Korean jazz group and says it was chosen as a Best of Choice in the April 2005 issue of MM Jazz. It has twelve tracks, among them Astor Piazzolla's "Oblivion", Antonio Carlos Jobim's "Bonita" and the group's own "It Rains" and "Lullaby". At the third Korean Music Awards, held in 2006, Triologue won Best Jazz & Crossover Song for "It Rain" and the general Best Performance award. The trio returned with Too Soon Too Late (Mirrorball Jazz World, MJW0129, listed on Discogs as December 2014), another twelve-track set with the same three players; Discogs files its bass credit under the Hangul spelling of his name.

Bass-led groups followed in the same years. The C2K Trio paired him with the drummer Chris Varga and the tenor saxophonist Kenji Omae, both foreign-born, on Unbalanced Beauty (2006), a record of nine originals, three by each player, and Cole Porter's "Just One of Those Things". A Korean review of the album notes that two of the three players are foreigners but argues that, given their long ties to Korea, the record is Korean, and says it was produced by Ha Jong-wook. The trio's Symmetry, which features David Berkman, is listed at the end of 2009 on Bugs and as a 2010 release in Kim Changhyun's own profile. In 2008 he, Oh Jong-dae and the pianist Yu Seung-ho, newly home from studies in Paris, formed the Neo Traditional Jazz Trio, a deliberately accessible piano trio whose Introducing Neo Traditional Jazz Trio appeared around the turn of 2010 and whose second album, When I Walk With You (2014), consists of Yu's compositions in Brazilian, Cuban, French and Irish styles. A March 2010 notice in Newsis announced a spring concert for the trio with the singer-songwriter Kwon Jin-won as guest vocalist.

His own name first appears on a record with Reverberation (잔향), released on August 7, 2012 by the audio specialist Audioguy. It is the live recording of a concert he gave at Olympus Hall that February, played by a quartet also called Reverberation: Kim on double bass, the drummer Kim Chaek (김책) and the guitarists Oh Jeong-su (오정수) and Hyuck Bang (방혁), both on guitar and effects. The nine parts follow the concert's unbroken flow of his own pieces. Its release text describes a cool but beautiful picture of loneliness and the city, with Part 5 about the plight of mammals living like crustaceans and Part 6 a ballad for middle-aged people struggling to get by. A News1 notice of September 20, 2012 announced a concert by him at the U-Square Culture Hall in Gwangju on the 23rd of that month.

Oblivion (망각) is the record that made his name. Its release text, which dwells on the experience of colonialism and on the cultural asymmetry that the writer says can be turned into artistic strength, says that Kim, Oh Jeong-su and Lee Ha-yoon (이하윤) performed a piece titled "Postcolonialism" in autumn 2013 in a collaboration with the LIG Culture Foundation, and that the EP is the live recording of that performance. It is in seven parts. The Korean Music Awards named it the best jazz and crossover performance at the 12th ceremony at the Mapo Art Center in Seoul on February 26, 2015, while the same category group went to the pianist Lee Sun-ji's The Night of the Border (jazz album) and Han Seung-seok and Jung Jae-il's Bari abandoned (crossover album). On April 10, 2015 he followed it with a contemporary music performance called Blooming (개화) in the small Garam Theater at Yongsan Art Hall, with Oh Jeong-su and the saxophonist Kim Seong-wan.

From 2017 his records are made with a steady circle on the label The Arts Label (TAL), whose producer and sound designer Seungkyun Chae (채승균) co-produces them. Deconstruction (해체, 解體), with the saxophonist Sungwan Kim and the drummer Sunki Kim, was issued on November 21, 2017 according to the label's release page, and appeared digitally on January 3, 2018. It is twenty short parts of free improvisation. MM Jazz's Kim Hee-jun, reviewing it on October 31, 2018, said it had no composed frame, that the three players agreed beforehand to break the music into short sections, and that it is best heard whole; the Jazz Space site had already put it among its 15 best Korean jazz albums of 2017. Representation (관념, 觀念, October 26, 2018) is a sequel with the guitarist Jun Kim, twenty-three parts of his own pieces recorded at TAL Studio. Kim has given the later records one-word Korean titles with Chinese-character equivalents, and the release texts tie them to a recurring subject, how a person recognizes himself and the world.

Noise (소음, 騷音, October 29, 2019) turned to electric instruments and effects. Its text says Kim steps outside the twelve-tone system to praise the beauty of machine civilization, with Jun Kim on guitar and effects and Chae mixing and adding effects; Kim designed the cover. Intuition (직관, July 15, 2021) puts his electric bass with Jun Kim, Sungwan Kim on alto saxophone and Sunki Kim on drums in five parts, one of them nearly 29 minutes long. Contemplation (관조, October 15, 2021) has four long parts in which, the text says, guitar, saxophone, bass and drums take turns circling the listener. Binary Connect (November 30, 2022), supported by the Seoul Foundation for Arts and Culture, documents a performance with no audience in the room and an online audience listening in binaural sound, with the first half reversed in real time and played over. Dey Kim is credited on modular synthesizer. Absolute Distance (October 17, 2023) is a "double trio" in which two trios play at once, Kim with Sungwan Kim and Sunki Kim on the left channel and Jun Kim, the tenor saxophonist Kim Jeongje and the drummer Gyuwon Jo on the right. Independency of Wave (March 26, 2024), a duo with Jun Kim on bass and electric guitar, is the most recent. It acknowledges support from Dong Seoul University's research support center, and is the tenth record under his name, one more than English Wikipedia lists.

Several people of the same name work in the Korean music world. A Discogs credit for "Kim Chang Hyun" on a K-pop group's record and a vocalist who issues singles under the same Hangul name on Apple Music are not him, and a Spanish-language C2K Trio with 2017 releases is a different group from his trio. Spotify also lists an unrelated Triologue album, Concepts (2010).

No interview in which he names his influences was found, so this section sticks to what the records and their reviews show.

His work divides into three phases. In the mid-2000s he played in guitar and saxophone trios whose repertoire mixes originals with standards, and in the Neo Traditional Jazz Trio, which aims to make jazz easy to approach. From Reverberation onward the records are his own projects. MM Jazz's 2018 review says his leader records rest on free improvisation and interplay among the players, which can come out as free jazz, as on Deconstruction, or on a quite rock-like sound base, as on Oblivion.

The second constant is the concept behind each record. Oblivion and Deconstruction are framed around postcolonial identity and the position of a non-Western artist, Noise around machines and speed, Contemplation around attentive listening to everyday sound, and Binary Connect and Absolute Distance around digital space and the distance between two simultaneous performances. From Noise on, the sound design by Seungkyun Chae and effects on the bass and guitar are part of the compositional idea, and his instrument is as often electric bass as double bass.