Cheon Soo-yeon (born Cheon Seong-im on August 15, 1981), better known by her stage name Song Ji-hyo, is a South Korean actress and model.
 She made her acting debut in "Wishing Stairs" (2003), one of the horror "Whispering Corridors film series".
 She then received further recognition for her roles in the romantic comedy drama "Princess Hours" (2006), the historical drama "Jumong" (2006), the historical film "A Frozen Flower" (2008), the crime film "New World" (2013), the romantic comedy drama "Emergency Couple" (2014), and family melodrama "My Wife's Having an Affair this Week" (2016).
Whispering Corridors (; also known as Ghost School and Ghost School Horror) is a South Korean horror film series.
 The series uses an all-girls high school as the backdrop for each of its films and doesn't share a continuing plot.
 Every "Whispering Corridors" film features a different plot, characters and settings.
 The series is notable for helping generate the explosion of the New Korean Wave cinematic movement, and dealing with taboo topics such as authoritarianism in the harsh South Korean education system, gay relationships and teen suicide, following the liberalization of censorship.
Kim Ok-bin (born December 29, 1986) is a South Korean actress.
 Kim made her debut in an online beauty contest in 2004, and began her acting career with a role in 2005 film "Voice".
 Subsequent appearances include the television drama series "Over the Rainbow" and films such as "Dasepo Naughty Girls" and "The Accidental Gangster and the Mistaken Courtesan".
 Kim has received several award nominations, and won Best Actress at the 2009 Sitges Film Festival for her role in "Thirst".
Whispering Corridors () is a 1998 South Korean horror film.
 It was part of the explosion in Korean cinema following the liberalization of censorship in the aftermath of the end of the country's military dictatorship, and makes a strong social commentary on authoritarianism and conformity in the harsh South Korean education system.
Voice ( also known as Whispering Corridors 4: Voice and Voice Letter) is a 2005 South Korean horror film, and the fourth installment of the "Whispering Corridors" film series.
 This film was the debut film for its three young actresses, as well as director Choi Ik-Hwan, who had served as an assistant director on the first film of the series.
Yoon Ji-hye (born November 10, 1979) is a South Korean actress.
 Yoon made her acting debut in the 1998 horror movie "Whispering Corridors".
 She has since starred in films such as "Possible Changes" (2004), "No Mercy for the Rude" (2006), and "", as well as the television series "Que Sera, Sera" (2007).
Wishing Stairs ( also known as Whispering Corridors 3: Wishing Stairs) is a 2003 South Korean horror film.
 It is the third installment of the "Whispering Corridors" film series set in girls high schools, but, as with all films in the series, is unrelated to the others; apart from a song being sung in one scene that is a pivotal plot in "Voice".
A Blood Pledge (Hangul: 여고괴담 5: 동반자살 ; RR: "Yeogogoedam 5: dongbandjasal " ; also known as Whispering Corridors 5: A Blood Pledge and Suicide Pact) is a K-Horror film, and the fifth installment of the "Whispering Corridors" series of South Korean horror films set in girls' high schools that began with 1998's film of the same name.
 Aside from the setting and overall themes, it is unrelated to the other films in the series.
Memento Mori ( also known as Whispering Corridors 2: Memento Mori) is a 1999 South Korean horror film, and the second installment of the "Whispering Corridors" film series.
 It is a sequel to 1998's "Whispering Corridors", and is also set in an all-girls high school, but the films are otherwise unrelated.
 "Memento Mori" was one of the first Korean commercial films to depict lesbian characters.
 However, prevailing Korean attitudes constrained its potential to be widely viewed, even more so as the controversial themes targeted the teen demographic.
Dead Friend (; lit.
 "The Ghost") is a 2004 South Korean horror film.
 It is one of a number of South Korean horror films set in high school; the trend began with 1998's "Whispering Corridors".

Question: Kim Ok-bin (born December 29, 1986) is a South Korean actress, Kim made her debut in an online beauty contest in 2004, and began her acting career with a role in 2005 film "Voice", Voice is a 2005 South Korean horror film, and which number installment of the "Whispering Corridors" film series?
Answer: fourth