## 3 Port COBie Schema for Digital Data-Based Facility Management
### Development of Port COBie Schema
#### 3.3.2 Port COBie Schema Developing Process  
Port maintenance data analysis describes the process of deriving the components of port COBie. The component derivation consists of four steps: classification, categorization, generalization, and normalization. In the listing step, we derived all elements required for  
Figure 5: The references for developing the port COBie Schema.  
port maintenance through analysis of the existing literature or maintenance systems. We referred to existing port facilities for the maintenance history, decision-making information, and property classification system. Within the system, the components required for port COBie were listed by referring to LandXML, CityGML, and InfraGML. Using the results of the listing step, the question of whether to include certain components in COBie and to reflect it in each COBie worksheet were decided via categorization. Figure 5 depicts the process of this step; in it, we decided whether to include something in COBie or not, according to assessments of the degree, performance, and risk, as well as the properties of each classification obtained via listing.  
In generalization, the COBie worksheets were organized according to the required, optional, and maintenance properties. According to the COBie structure, each sheet was allocated several properties, and the properties were classified into \"required,\" \"reference to other sheets,\" \"external reference,\" and \"optional.\" Therefore, it was necessary to determine whether newly created sheets in Port COBie or newly added properties in existing sheets were required or optional. Figure 6 shows the two-step categorization process.  
In the final normalization step, the selected COBie components were determined by examining the adequacy of each property and the errors in the results of generalization. Figure 7 shows the composition of the port COBie worksheet selected through classification, categorization, generalization, and normalization. Port facility maintenance information can be defined in the design, construction, and trial operation phases according to the project characteristics and the client's requirements; however, the maintenance data generation undertaken directly or indirectly in the operation phase is also important ([PERSON] et al., 2021). Although regular inspections and precise safety diagnoses are performed periodically for port maintenance (according to South Korean law), the method is unsystematic with the inputs generated non-digitally, hindering management. Therefore, the operation part (absent from existing COBie systems in the construction field) was newly added to the port COBie system. Figure 8 shows the port COBie worksheet configuration applied in this study. In the design phase, \"Floor\" in the construction COBie was deleted, and \"Equipment\" and \"System\" were added alongside \"Facility,\" \"Space,\" \"Zone,\" and \"Component.\" \"Subsidiary\" (additional) provides information on auxiliary facilities; it was added into the construction phase. In the newly added operation phase, the \"Performance,\" \"Degradation,\" and \"Damage History\" tabs were added to create and input the information generated by each subject in the operation phase. This reflected information such as port facility history management, deterioration prediction, and performance analysis. Furthermore, breakdown and identification were added to the common properties, to provide a classification and recognition system for port facilities. The port BIM COBie schema was configured as described below. Using the developed port schema, the next section develops an environment that facilitates the direct input of COBie data into the BIM environment.  
Figure 6: Determining COBie components—categorization.