论不当得利要件的重构——兼评不当得利请求权与相关请求权竞合
론불당득리요건적중구——겸평불당득리청구권여상관청구권경합
The Reconstruction of Unjust Enrichment Constitutive Requirements --Discussion of Concurrence of Claim for Returning Unjustified Enrichment and Other Claim