Founder of the Chogye Byeon clan; said to have passed the civil examination under King Seongjong of Goryeo, served as chancellor and been made Prince Palgye (posthumous title Munyeol)

| Era | 고려 전기 |
| Clan | 초계 변씨 |
Byeon Jeong-sil (卞庭實) is the founder of the Chogye Byeon clan. He is said to have passed the civil examination under King Seongjong of Goryeo, risen to munha sijung (chancellor) and been made Prince Palgye (八溪君); the Chogye Byeon head association gives his posthumous title as Munyeol (文烈). His dates are not recorded. The clan seat Chogye is the area around today's Chogye-myeon, Hapcheon County, South Gyeongsang, and the title 'Palgye' is the old name of that town.
As for earlier ancestry, tradition holds that Byeon Won (卞源), a Tang minister of rites, came to Silla in 743 (the 2nd year of King Gyeongdeok) bringing the Classic of Filial Piety. The lineage presented by the head association runs from Won through Si, Gyejo, Cheol, Yong, I, Hu, Gwan, Gunyeon and Seop down to Jeong-sil, who is counted as the 11th-generation descendant of Si. Korean Wikipedia, however, explains that the generations after Byeon Won were lost and that the documented line begins with Jeong-sil, so accounts differ slightly.
Jeong-sil is said to have had three sons. The eldest, Byeon Gwang (卞光), founded the Jang-pa; the second, Byeon Yo (卞耀), the Jung-pa; and the third, Byeon Hwi (卞輝), the Gye-pa, the three trunks of the clan today. Byeon Yo's grandson Byeon Go-jeok (卞高迪) settled in Miryang and founded the Miryang Byeon as a separate seat, so the Chogye and Miryang Byeon are regarded as one family by origin.
Chogye was called Chopalhye-hyeon in Silla, renamed Palgye under King Gyeongdeok, and given the name Chogye in 940 (23rd year of Taejo of Goryeo). Jeong-sil's title Prince Palgye is said to come from this old name. The area remained Chogye-gun until the end of Joseon and was merged into Hapcheon in 1914 as Chogye-myeon.
The head association's short history gives Jeong-sil as the 11th-generation descendant of Si after Byeon Won and records his posthumous title as Munyeol. A caption on that page gives the year of his examination success as 965, which does not fit King Seongjong's reign (981-997) and needs checking, so no exam year is asserted here.
From the eldest son Byeon Gwang came the Jang-pa, in which Byeon Nam-ryong's six sons each founded a sub-branch; the second son's grandson Byeon Go-jeok founded the Miryang Byeon; and the youngest son Byeon Hwi's descendants form the Gye-pa. See the Jang-pa, Jung-pa and Gye-pa descriptions on the clan page.
The head association lists a founder's tomb among its relics and sites, but its location was not confirmed here.
His three sons Byeon Gwang (Jang-pa), Byeon Yo (Jung-pa) and Byeon Hwi (Gye-pa) are said to have founded the three branches.