"Chung, S. Y. and Lee, W. Y. (2013). “A study on the estimation function of the operation
cost for an urban railway (with a focus on medium-sized rapid transit).” Journal of
the Korean Society for Railway, Vol. 16, No. 4, pp. 318-330, https://doi.org/10.7782/JKSR.2013.16.4.318
(in Korean)."
