Map of Korean dialects/languages
Own work

outline data from Natural Earth 10m
six major jialect areas in Korea from National Geography Information Institute (2017)       The National Atlas of Korea, Seoul:  Ministry of Land Infrastructure and Transport, p. 37  
Yukchin in Korea: King, J. R. P. (1987), "An introduction to Soviet Korean", Language Research 23(2): 233–274, map on p. 237, reproduced from Kim Thay Kyun (1983), p. 34.
Hamgyŏng and Yukchin in China (where they are called North-central and Northeast respectively): Chinese Academy of Social Sciences (2012), Zhōngguó yǔyán dìtú jí (dì 2 bǎn): Shǎoshù mínzú yǔyán juǎn 中国语言地图集: 第2版. 少数民族语言卷 [Language Atlas of China (2nd edition): Minority language volume], Beijing: The Commercial Press, ISBN 978-7-100-07053-9, Map C1-7.
Kanguole