It is often claimed that the descriptive way of documentation is insufficient to define software requirements as being unambiguous. This is caused by not only the difference of knowledge and understanding of the stakeholder as to system but also the difference in the way of documentation like method of representation as well as depth of description. The study explains the process and results of applying a diagraming tool like UML to improve the requirements of GLORY(GLObal Resource management sYstem) initially defined in descriptive way. Especially, the result shows that the requirements are more accurately improved with the good hierarchies and well-leveled functionalities, with the help of diagraming tool, expecting easy maintenance of requirements and prevention of omission of requirements.