Yi Cha-ch'un

Posthumous name
	First: King Hwan (환왕, 桓王; given in 1392 by King Taejo); Last: King Yeonmu Seonghwan the Great (연무성환대왕, 淵武聖桓大王; given in 1411 by King Taejong);
Temple name
	Hwanjo (환조, 桓祖)

Yi Cha-ch'un
이자춘
李子春
Yi Cha-ch'un; 이자춘; 李子春
King of Joseon (posthumously)
Darugachi
Reign	1343–1356
Born	20 January 1315; Aldong, Ssangseong Prefecture, Yuan dynasty; (now Gyeongheung-gun, North Hamgyeong Province)
Died	3 June 1361 (aged 46); Gwiju-dong, Hamheung-bu, Dongbuk-myeon, Goryeo; (now Yeongheung-gun, Hamgyeongnam-do)
Burial	Jeongneung tomb; Hamju County, South Hamgyeong Province, North Korea
Spouse	Lady Yi; Queen Uihye
Issue	5 sons and 1 daughter
Posthumous name
Posthumous name
	First: King Hwan (환왕, 桓王; given in 1392 by King Taejo); Last: King Yeonmu Seonghwan the Great (연무성환대왕, 淵武聖桓大王; given in 1411 by King Taejong);
Temple name
	Hwanjo (환조, 桓祖)
House	Jeonju Yi
Father	Yi Chun
Mother	Lady Bak of the Munju Bak clan

Yi Cha-ch'un (Korean: 이자춘; Hanja: 李子春; 20 January 1315 – 3 June 1361) or known by his Mongolian name Ulus Bukha (Korean: 울루스부카; Hanja: 吾魯思不花), was a minor military officer of the Yuan Empire who later transferred his allegiance to Goryeo and became the father of Yi Sŏng-gye, founder of the Joseon Dynasty.