Dear Wolfgang,

Remove the space:

\definefont[test][file:kopubbatangprolight*default]

\definefont[test][file:KoPubBatang_ProMedium*default] It didn't work at the first try, and I realized that I didn't reformat ConTeXt after installing this new fonts. After reformatting, ConTeXt found the fonts and worked fine. Thank you and Happy New Year! Best regards, Dalyoung