# BIM-Based Management System for Off-Site Construction Projects
## 4 System Implementation
### System Functions and Implementation Detail
#### 4.3.3 Production Management  
The system involves a production planning and monitoring function for the stream-lined execution of the production stage, which accounts for a large proportion of the OSC project. Production managers can use the system to establish a plan for the lead time and expected installation date of the target component and produce the component accordingly. The users can calculate the appropriate lead time after reviewing the production drawings saved as the attribute information of the component. Moreover, the system can establish a mold plan, such as that of a PC component, when necessary. On the production plan screen, the production schedules of the components with a lead time are automatically calculated and displayed as a matrix. Production managers can not only adjust and customize the plan but also rapidly identify missing components. Additionally, the system can track the production status of the components. Using the production status tracking function, users can perform JIT management of the OSC projects with thousands of components or more. The products undergo sequential positional and situational changes until they are finally  
Figure 4: UI for project zone planning.  
integrated into a complete structure onsite. In many OSC projects, the sensors are attached to components to manage them from the final point of production. The proposed system can store the tagged data (i.e., date and location) as attribute information of the component in the DB. The finished product is moved to a yard or warehouse and awaits delivery requests from the site. As soon as the producer tags these components, the information sent to the management system allows other participants in the project to determine the production status.  
The production planning system is automated through BIM object-based information management. In establishing a production plan for an OSC project, the key factors are the quantity, lead time, and delivery date of each component. The management system has an object-based environment in which each 3D model has a unique ID and various attribute information. The production quantity is calculated by assigning the same product number to components with the same shape and joint information. In general, the product lead time must be determined after carefully examining the drawings. The proposed C#-based management system reads BIM information through xbim and visualizes it as a 3D view by.NET-based DevDept Eyeshot. In this case, the 2D and 3D information is stored and linked to each component as a CDM. Therefore, when the user right-clicks a component on the 3D view screen, the production drawing appears (Figure 5). Managers can use this multidimensional BIM information to accurately estimate the product lead time.  
To track and manage the product status offsite, technologies such as RFID and real-time location systems (RTLS) are fused with the BIM-based attribute information integrated-management technology for each component. RFID is used to identify a component and generate attribute information on the BIM. This RFID framework consists of a tag for identification, a reader for sensing, and an antenna for data transmission and reception. Once the antenna and reader are installed at the appropriate place, the nearby component can be recognized by receiving its information from the tag. Anticipating the occurrence of unintentionally repeated tagging, we process the data in an FTP format with the controller and finally transmit it to the system without duplicate noise. The data required to be transmitted and received through RFID include not only the ID and time but also the exact location of a component (determined using the RTLS). Bluetooth low energy, which has a small error range and low cost, is used to track the factory inventory and installation location in real time.  
Figure 5: Three-dimensional model view–2D shop drawing linkage.