GS Caltex Cup
The full name of this tournament is the GS Caltex Cup (Korean: GS칼텍스배). It is a Korean domestic tournament sponsored by GS Caltex. Until 2004, the tournament was known as the Korean LG Cup or LG Refined Oil Cup , as LG sponsored this new tournament, which started in 1996 when the Kiwang title was replaced by the international LG Cup.
 valerio gave the plural Oils. Wikipedia gives the singular.
In 2005, LG split into two separate groups, LG and GS, hence the name change for this tournament.
In 2005, this was one of the most lucrative domestic Korean professional tournaments, with 50 million Won for the winner and 15 million Won for the runner-up. From 2012, first prize raised to 70,000,000 Won.
Winners of the Korean LG Cup:
1st (1996) Yu Chang-hyeok (d. Cho Hun-hyeon) 2nd (1997) Lee Changho (d. Choe Myeong-hun) 3rd (1998) Lee Changho (d. Choe Myeong-hun) 4th (1999) Seo Pong-su (d. Yu Chang-hyeok) 5th (2000) Choe Myeong-hun (d. Rui Naiwei) 6th (2001) Lee Changho (d. Choe Myeong-hun) 7th (2002) Lee Sedol (d. Choe Myeong-hun) 8th (2003) Lee Changho (d. Cho Han-seung) 9th (2004) Lee Changho (d. Pak Yeong-hun)
Winners of the GS Caltex Cup:
10th (2005) Choe Cheol-han (d. Lee Changho) 11th (2006) Lee Sedol (d. Choe Cheol-han) 12th (2007) Pak Yeong-hun (d. Lee Sedol) 13th (2008) Pak Yeong-hun (d. Weon SeongChin) 14th (2009) Cho Han-seung (d. Pak Yeong-hun) 15th (2010) Weon SeongChin (d. Cho Han-seung) 16th (2011) Park Junghwan (d. Pak Yeong-hun) 17th (2012) Lee Sedol (d. Pak Yeong-hun) 18th (2013) Kim Jiseok (d. Lee Sedol) 19th (2014) Kim Jiseok (d. Choe Cheol-han) 20th (2015) Mok Jinseok (d. Choe Cheol-han) 21st (2016) Lee Donghoon (d. Yun Chanhee) 22nd (2017) An Kukhyun (d. Kim Jiseok) 23rd (2018) Shin Jinseo (d. Lee Sedol) 24th (2019) Shin Jinseo (d. Kim Jiseok) 25th (2020) Shin Jinseo (d. Kim Jiseok) 26th (2021) Shin Jinseo (d. Park Junghwan)
valerio: the prize money for this tournament is the the second in korean scene. Previous name was LG Refined Oils (from term 1 to 9).
valerio: till 2009 the challenger was selected by a robin round (players). From 15th edition the tournament turned into a knockout system (24 players).