54) to the Chosen Government Railway. These, along with those belonging to the North China Transportation Company and the Central China Railway together which the total number of the type was over 1400, were taken over by the Republic of China Railways in 1945. After the establishment of the People's Republic of China, the newly formed China Railway designated the former Mikai class ㄇㄎ壹 (MK1) class in 1951, whilst retaining their previous road numbers. Mantetsu ミカイ1 − ミカイ341 became ㄇㄎ壹1 − ㄇㄎ壹341, MNR ミカイ501 − ミカイ1283 became ㄇㄎ壹501 − ㄇㄎ壹1283, the North China Transport ミカイ1501 − ミカイ1909 became ㄇㄎ壹1501 − ㄇㄎ壹1901, whilst the locomotives from the Central China Railway and other railways became ㄇㄎ壹1902 − ㄇㄎ壹2023. In 1950, the Sifang Works began assembling new Mikako type locomotives using parts that remained on hand after the war. The first of these, ㄇㄎ壹2101國慶號 (MK1 2101 "National Day"), was completed in September 1950, as the first locomotive to be built in the People's Republic of China. The second, ㄇㄎ壹2102八一號 (MK1 2012 "1 August"), was completed on 26 July 1952, and subsequently another eighteen, numbered 2103 through 2120, were built out of parts on hand. The first ㄇㄎ壹 to be built new in the PRC using newly made parts was ㄇㄎ壹2121, completed at Sifang in December 1952, after which a further 57 were built, numbered 2122 through 2177. Under the direction of Jiu Qu (瞿赳), Deputy Chief of the Rolling Stock Industry Authority of the Ministry of Machinery Industry, extensive work to revise the Mikako design was undertaken in 1953. This included converting all dimensions from Imperial measures to metric, improving tolerances, and ensuring that everything met domestic materials standards. The first locomotive built to the refined standards was ㄇㄎ壹2178, completed in December 1954 at the Dalian Works. The new design was slightly longer ( vs ) and had a power output rated at compared to the of the previous designs. In 1957 engineers at the Dalian Works further improved the design, leading to the 建設 (JS) (Jiànshè, "Construction") class locomotives. In 1958, the first locomotive to be built by a locomotive depot in China, as opposed to at a factory, was ㄇㄎ壹4101; this was built in ten days in October of that year, as part of a Great Leap Forward speed challenge. In 1959, China Railways introduced a new classification system, under which all locomotives with 2-8-2 wheel arrangement were named 解放 (Jiefang,