Well I don't guess the Dorco is #1, still it's #2, they hold about 20~30% of market. Gillette is a big #1 razor in S.Korea, about 60%.
I'm not Korean but I've lived here for 15 years. I can speak, read and write ㅋㅋ. Are you Korean? If you want some tips on buying shaving gear and shipping to Korea send me a PM.