The Korean VLBI Network (KVN) is a very long baseline interferometry (VLBI) network in Korea that operates at millimeter wavelengths. It consists of four 21-meter radio telescopes located in Seoul, Ulsan, PyeongChang, and Jeju Island, Korea: the KVN Yonsei Radio Observatory (KYS), KVN Ulsan Radio Observatory (KUS), KVN PyeongChang Radio Observatory (KPC), and KVN Tamna Radio Observatory (KTN). The baseline lengths of the KVN range from 130 to 500 km, giving it an effective spatial resolution equivalent to that of a 500-km radio telescope.

All four antennas have an identical design and are equipped with a quasi-optical system that enables simultaneous observations at 22, 43, 86, and 129 GHz. Since August 2013, the KVN Ulsan has also operated at 6.7 GHz in both single-dish and VLBI modes, primarily for observing 6.7-GHz class CH₃OH masers. Additionally, a GPS receiver has been installed at each KVN station. By estimating the atmospheric wet delay and total electron content over all KVN stations, the accuracy of phase referencing and astrometric observations has been improved.

The KVN began operations in 2013 with radio telescopes in Ulsan, followed by Yonsei and Tamna. In 2024, with the commencement of operations at a newly installed radio telescope in PyeongChang, the network expanded, enabling more detailed and comprehensive observations. This expansion is expected to significantly enhance the performance of observation results.

The KVN was built by Korea Astronomy and Space Science Institute (KASI) for achieving the main goals

1. to study the formation and death of stars with observing water (H2O), methanol (CH3OH), and silicon monoxide (SiO) masers at high resolutions.
2. to investigate the structure and dynamics of our own Galaxy by conducting highly accurate astrometric VLBI observations toward the galactic radio sources.
3. to study the nature of active galactic nuclei (AGN) and their population at high frequencies.
4. The KVN as a dedicated-VLBI network also aims to study the spectral and temporal properties of transient sources such as bursting star-forming regions, intra-day variable compact radio sources, gamma ray flaring AGNs, etc by conducting systematic multi wavelength monitoring campaigns

Reference : Kim et al. 2004, Proc. 7th Symp. EVN, 281 /  Lee et al. 2011, PASP, 123, 1398  /  Lee et al. 2014, AJ, 147, 77