The mopheme {jom} has been generally described as a abbreviated form of the adverb {jogeum}. But {jom} shows many particular behaviors that could not be explained if it be az adverb. We separate {$jom_2$} as a sort of determiner from {jom$_1$} as a shortened form of the adverb {jogeum}. {$jom_2$} , as a determiner, has a function similar to the Korean determiners {ga, leul}, which means that {$jom_2$} and {ga}, {leul} can be compared with the French indefinite article {un} or partitive article {du, de la, des}. We assert that {$jom_2$} plays two main roles. The one is the role of introducing a new information and focusing an entity in the discourse. {$jom_2$} has a correlation with the presupposition, also. The other role is related with modality. The function {$jom_2$} doesn t lie so much in politeness in the speech level as generally accepted, as in demand in the other of modality.