Question: When did the country where the manufacturer of Koksan is located split from the country of My Boss, My Teacher?

full_context: Document 1: AEK-971: The AEK-971 is a Russian (formerly the Soviet Union) selective fire 5.45×39mm assault rifle that was developed at the Kovrov Mechanical Plant (KMZ) by chief designer Sergey Koksharov in the late 1970s and 1980s (currently manufactured by Degtyarev Plant).
Document 2: Korean War: The Demilitarized Zone runs northeast of the 38th parallel; to the south, it travels west. The old Korean capital city of Kaesong, site of the armistice negotiations, originally was in pre-war South Korea, but now is part of North Korea. The United Nations Command, supported by the United States, the North Korean People's Army, and the Chinese People's Volunteers, signed the Armistice Agreement on 27 July 1953 to end the fighting. The Armistice also called upon the governments of South Korea, North Korea, China and the United States to participate in continued peace talks. The war is considered to have ended at this point, even though there was no peace treaty. North Korea nevertheless claims that it won the Korean War.
Document 3: Gangnam Blues: "Gangnam Blues" was released in 684 theaters in South Korea on January 21, 2015. Despite its "restricted" rating, it topped the box office on its opening day, with 152,500 tickets sold. Within 5 days, it had reached the 1 million admission mark (1,097,103). After 35 days of release, the film recorded 2.19 million admissions.
Document 4: Koksan (artillery): The M-1978 Koksan is a 170 mm self-propelled gun of North Korean design and manufacture. Very little information is available due to the secretive nature of the North Korean government. The designations "M-1978" and "Koksan" were given to the type by American military analysts, as they first became aware of it in that year in Koksan, North Korea.
Document 5: My Boss, My Teacher: "My Boss, My Teacher" was released in South Korea on 19 January 2006, and topped the box office on its opening weekend with 1,106,825 admissions. It held the number-one spot for a second consecutive week, and went on to receive a total of 6,105,431 admissions nationwide, making it the fourth best selling film of 2006, and—until surpassed by "200 Pounds Beauty" in early 2007—the most successful Korean comedy film of all time. As of 5 February 2006, the film had grossed a total of $30,585,589.
Document 6: KM-SAM: The KM-SAM is the middle-tier of South Korea's three-tier aerial and missile defense system. Though it was developed in Russia by the Almaz Design Bureau with assistance from Samsung Thales, LIG Nex1, and Doosan DST, localization and industrialization were done in South Korea enough to consider it an indigenous system. The Cheongung (Iron Hawk) can intercept targets up to an altitude of at a range of . It is to replace upgraded MIM-23 Hawk batteries in South Korea and be made available for export. Almaz-Antey continued with the program after prototypes were transferred and have created a distinctly Russian version called the Vityaz missile system.
Document 7: Korean War: By mid-1950, North Korean forces numbered between 150,000 and 200,000 troops, organized into 10 infantry divisions, one tank division, and one air force division, with 210 fighter planes and 280 tanks, who captured scheduled objectives and territory, among them Kaesong, Chuncheon, Uijeongbu, and Ongjin. Their forces included 274 T-34-85 tanks, 200 artillery pieces, 110 attack bombers, some 150 Yak fighter planes, 78 Yak trainers, and 35 reconnaissance aircraft. In addition to the invasion force, the North KPA had 114 fighters, 78 bombers, 105 T-34-85 tanks, and some 30,000 soldiers stationed in reserve in North Korea. Although each navy consisted of only several small warships, the North and South Korean navies fought in the war as sea-borne artillery for their in-country armies.
Document 8: History of Korea: After the end of WWII in 1945, the Allies divided the country into a northern area, protected by the Soviets, and a southern area protected primarily by the United States. In 1948, when the powers failed to agree on the formation of a single government, this partition became the modern states of North and South Korea. The peninsula was divided at the 38th Parallel: the ``Republic of Korea ''was created in the south, with the backing of the US and Western Europe, and the`` Democratic People's Republic of Korea'' in the north, with the backing of the Soviets and the communist People's Republic of China. The new premier of North Korea, Kim il - Sung launched the Korean War in 1950 in an attempt to reunify the country under Communist rule. After immense material and human destruction, the conflict ended with a cease - fire in 1953. The two nations officially remain at war because a peace treaty was never signed. Both states were accepted into the United Nations in 1991.
Document 9: You Are the Apple of My Eye: In Singapore "You Are the Apple of My Eye" earned a total of SGD$675,000, making it the second-highest-grossing film in Singapore that weekend despite the film's NC-16 rating (which meant that only viewers over age 16 were admitted); this surprised the film's distributor, 20th Century Fox. The film broke the record for highest opening weekend for a Taiwanese film in Singapore, previously held by the 2007 film "Secret". It surpassed the performance of other Taiwanese films such as "Monga", "Cape No. 7" and "Lust, Caution". "You Are the Apple of My Eye" was the highest-grossing Asian film of 2011 at the Singapore box office, with earnings of SGD$2.93 million.
Document 10: Division of Korea: The subsequent Korean War, which lasted from 1950 to 1953, ended with a stalemate and has left the two Koreas separated by the Korean Demilitarized Zone (DMZ) up to the present day.
Document 11: The Face Reader: "The Face Reader" became one of the highest-grossing films in South Korea in 2013, with 9.1 million admissions. It won six awards at the 50th Grand Bell Awards, including Best Film, Best Director for Han Jae-rim, and Best Actor for Song Kang-ho.
Document 12: My Mighty Princess: "My Mighty Princess" was released in South Korea on 26 June 2008, after a delay of more than two years. On its opening weekend it was ranked eighth at the box office with 14,988 admissions; as of 6 July it had received a total of 27,309 admissions, with a gross of .
Document 13: Nuclear weapon design: In 1999, nuclear weapon design was in the news again, for the first time in decades. In January, the U.S. House of Representatives released the Cox Report (Christopher Cox R-CA) which alleged that China had somehow acquired classified information about the U.S. W88 warhead. Nine months later, Wen Ho Lee, a Taiwanese immigrant working at Los Alamos, was publicly accused of spying, arrested, and served nine months in pre-trial detention, before the case against him was dismissed. It is not clear that there was, in fact, any espionage.
Document 14: Military Demarcation Line: The Military Demarcation Line (MDL), sometimes referred to as the Armistice Line, is the 154 mile - long land border or demarcation line between North Korea and South Korea. On either side of the line is the Korean Demilitarized Zone (DMZ). The MDL and DMZ were established by the Armistice at the end of the Korean War in 1953.
Document 15: Division of Korea: The division of Korea between North and South Korea occurred after World War II, ending the Empire of Japan's 35 - year rule over Korea in 1945. The United States and the Soviet Union each occupied a portion of the peninsula, with the boundary between their zones of control along the 38th parallel.
ground_truth: 1953
sub_queries: Koksan >> manufacturer Answer: North Korea
Which was the country for My Boss, My Teacher? Answer: South Korea
when did North Korea split from #2 Answer: 1953