HLA is (or was) a standard time and frequency radio station operated by the Korea Standards Research Institute’s Time and Frequency Laboratory in Daedeok (Taedŏk) Science Town (대덕연구단지) near the city of Daejeon (대전 or Taejŏn). HLA first came on the air on 5 MHz in 1984. I heard a rumor that they were no longer on the air. However, there is a reported logging of them in 2018. I have not been able to verify it either way. Listening to remote SDR receivers in the East Asia area, including Korea have so far proven negative.
They responded to my 1991 reception report with the QSL card displayed below. Additionally, I took a day trip and drove down to the station and was treated to a fine tour of their facilities.