...which is from 1945 to 1998.
Here's a relevant portion of the North Korea nuclear tests: timeline from The Telegraph:
<snip>
September 19, 2005 North Korea agrees to a preliminary accord under the renewed six-party talks that it would scrap all existing nuclear weapons and nuclear production facilities, rejoin the NPT and allow IAEA inspectors to return.
October 2, 2006 North Korean foreign minister announces that the country will conduct a nuclear test.
October 9, 2006 North Korea detonates a nuclear device with an estimated explosive force of less than one kiloton. China, which had reportedly attempted to convince the regime not to go ahead with the test, was given a 20 minute warning and flashed an emergency alert to Washington.
October 11, 2006 The United Nations Security Council imposes new sanctions on the already isolated regime.
May 25, 2009 North Korea detonates a second nuclear device and launches a number of short-range surface-to-air missiles. The yield of the test was put at close to 5 kilotons. The nuclear test was condemned by the Association of Southeast Asian Nations, the Comprehensive Nuclear Test Ban Treaty Organisation, the European Union, the Holy See, Nato, the Organisation for Security and Cooperation in Europe and the UN Security Council, which passed Resolution 1874 that tightened sanctions on the country.
<snip>
February 12, 2013 An underground explosion at North Korea's Punngye-ri nuclear test site is detected, with experts estimating the size of the blast at between 6 and 7 kilotons.