\documentclass{article}
\usepackage{kotex}
\usepackage{xparse}
\usepackage{xcolor}
\usepackage{jiwonlipsum}
\NewDocumentCommand\txtcol{lm}{\textcolor{#2}{#1}}
\begin{document}
\txtcol \jiwon[1]{blue!30}
\txtcol \jiwon[2]{blue!50}
\txtcol \jiwon[3-4]{blue!70}
\end{document}