<P> Time in North Korea, called Pyongyang Time (Chosŏn'gŭl: 평양 시간, Hancha: 平壤 時間 or PYT) or Standard Time of the Democratic People's Republic of Korea (Chosŏn'gŭl: 조선 민주주의 인민 공화국 표준 시간, Hancha: 朝鮮 民主 主義 人民 共和國 標準 時間), is since May 2018 equal to Korea Standard Time: 9 hours ahead of UTC (UTC + 9). Like South Korea, North Korea does not currently observe daylight saving time . Time keeping in North Korea is under the State Commission for Science and Technology . </P> <P> Before modern clocks were introduced into Korea, Koreans kept time with the help of a sundial during the daylight time and a water clock at night . In 1434, Jang Yeong - sil, a Joseon scientist and astronomer with other scientists, developed Korea's first sundial, Angbu Ilgu (앙부일구 / 仰 釜 日晷) and was put into service as standard time - keeper of the kingdom and began the standard time at Hanyang (Seoul) which was calculated to be UTC + 08: 28 . In 1442, Chiljeongsan, an astronomical calendar system that was created during the reign of King Sejong used Hanyang (Seoul) local time as its standard as it overcame the limitations of previous - made calendars . The Korean Empire adopted a standard time of ​ 8 ⁄ hours ahead of UTC (UTC + 08: 30), which is similar to Pyongyang Standard Time, around the beginning of the 20th century . Some sources claim 1908, others claim 1912 and yet another claims that mean local standard time was used prior to 1908 and that UTC + 08: 30 was used from 1 April 1908 to 31 December 1911 and again from 21 March 1954 to 9 August 1961 . In 1912, the Governor - General of Korea changed the time zone to UTC + 09: 00 to align with Japan Standard Time . </P> <P> On 5 August 2015, the North Korean government decided to return to UTC + 08: 30, effective 15 August 2015, and said the official name would be Pyongyang Time or (PYT). The government of North Korea made this decision as a break from "imperialism"; the time zone change went into effect on the 70th anniversary of the liberation of Korea . The South Korean government officials worried about inconvenience in Inter-Korean exchange and cooperation, including commuting to and from the Kaesong Industrial Region, and further difference of lifestyle between the North and South Korean people . </P> <P> On 29 April 2018, North Korean leader Kim Jong - un announced his country would be returning to UTC + 9 to realign its clocks with South Korea . On 30 April 2018, the Supreme People's Assembly of North Korea issued a decree about changing the time in North Korea as a further step in unifying Korea and eliminating differences between the South and North . The time change was applied at 23: 30 on 4 May 2018 (UTC + 8: 30). </P>

Why do north and south korea have different time zones