## 3 System Implementation for Serialized Track and Trace
### System Design and Implementation  
As shown in Figure 3, the structure of the system follows the EPCglobal architecture model, which is a standard model of RFID information services including EPCIS, ONS, and DS. It was completed by additionally developing application programs for production, shipping, receiving, and sequencing. In order to identify RFID tags and store the identification events in the information system, different types of RFID systems and several industrial computers were installed. Table 1 describes the summary of hardware configurations in each read point. For stable identification of RFID on the metal, we designed clip-type RFID metal tags and applied them on the top right side of rear axles. In order to reuse the tags, workers at the OEM plant need to detach the tags before assembly-line feeding and return them to the supplier plant via delivery trucks returning with the empty racks. Figure 4 shows the detailed specification and shape of the metal tags. For the rear axles produced at the supplier plant, the RFID's are read through the RFID antenna shown in Figure 5a, and the ID's are stored in the EPCIS. In addition, the rear axles are loaded onto the 7-racks after production (Figure 5b), and here, their parent-child relationships (parent: rack's ID, children: rear axles' ID) are also stored in the EPCIS. The production and 7-rack loading processes can be monitored by workers through the production monitoring application shown in Figure 5c. When shipping, the ID's of the 7-racks loaded onto the forklift in three layers are checked with the RFID antennas shown in Figure 6a, and by querying the EPCIS about the ID's with the parent keys (i.e., ID of the 7-rack), the ID's of individual rear axles on the pertinent 7-racks are queried. Thereafter, the ID's of the rear axles are immediately stored again in the EPCIS, and the shipping process is completed. Figure 7 depicts the data flows between EPCIS and the capturing application, and shows \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & **Supplier** & \multicolumn{2}{c}{**Consolidation Center**} & \multicolumn{2}{c}{**OEM**} \\ \hline  & **ReadPoint 1** & **ReadPoint 2** & **ReadPoint 3** & **ReadPoint 4** & **ReadPoint 5** & **ReadPoint 6** & **ReadPoint 7** \\ \hline \multirow{3}{*}{PC} & Touch-Screen & Touch-Screen Monitor, & Touch-Screen Monitor, & Touch-Screen Monitor, Body, & Monitor, Body, & Monitor, Body, & Monitor, Body, \\  & Speaker & & Body, Speaker & Speaker & Speaker & Speaker & Speaker \\ \hline \multirow{3}{*}{Reader} & \multirow{3}{*}{900 MHz Fixed Reader} & 900 MHz & 900 MHz & 900 MHz & 900 MHz & 900 MHz \\  & & Fixed Reader & Fixed Reader & Fixed Reader & Fixed Reader & & Fixed Reader \\ \hline Antenna & Linear \(\times\) 1 & Linear \(\times\) 2 & Linear \(\times\) 3 & Linear \(\times\) 1 & Linear \(\times\) 1 & \multicolumn{2}{c}{Linear \(\times\) 1} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of Hardware Configuration. Figure 3: System architecture. sample messages of the EPCIS query and query result for retrieving the information of the rear axles in a 7-rack. Furthermore, the shipped parts and 7-rack ID's can be checked by the workers through the shipping monitoring application shown in Figure 6b. Figure 4: Specification of radio frequency identification (RFID) metal tag. Figure 5: Production monitoring in the supplier plant. (**a**) Read point at production line; (**b**) Read point at 7-rack loading area; (**c**) Screen shot of production monitoring application. When the rear axles arrive at the consolidation center, an information flow similar to that of the shipping process at the supplier plant is created. As shown in Figure 8a, the ID's of the 7-racks loaded in three layers are read, and after fetching the ID's of the children rear axles by querying the supplier  
Figure 6: The shipping process at the supplier plant. (**a**) Read point at shipping area; (**b**) Screen shot of shipping application.