Proper noun is commonly understood as artificial name. As it is regarded to designate unique one, the referent of it is considered as the singular. Common noun may be regarded as the one which designate common properties or plural referents. But ``훈민정음`` is a proper noun, though it can refer many books. Both of ``해`` and ``달`` are common nouns, even though they refer the only things. So it cannot be true that proper noun cannot refer the plural and the common noun cannot refer the only thing. We should recognize that Koreans think all the artificial names belong to one category by intuition and that the grammar should be described systematically according to the intuition of the native speakers. Futhermore the Korean artificial names (including many brand names) which can refer plural things, has almost the same grammatical properties as the typical proper nouns. Therefore we can conclude that they belong to the category of proper nouns and that we should categorize proper nouns and common nouns according to the feather [±Artificial Naming].