## 4 Experiment and Discussion
### Results for Item Location Identification  
For the practical experiments, we extended the size of the MSR to four rows and five columns of 360 cm in width and 288 cm in length. For the given 20 zones, the unit zone size was same as the previous setting, and three items were loaded in each zone (i.e., a total of 60 items were loaded in the MSR) with a distance of 24 cm in between. The \(Rh\) and tag recognition interval were set at 35 cm and 0.3 sec, respectively, because, as demonstrated in Section 4.1, these are the optimum values  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Number of Stocked Items**} & \multicolumn{6}{c}{**Tag Recognition Intervals of the RFID Reader (sec)**} & \multicolumn{6}{c}{**Standard**} \\ \cline{2-10}  & **0.3** & **0.5** & **1** & **2** & **3** & **4** & **5** & **Mean** & **Standard** \\ \hline
**1** & 100 & 100 & 100 & 85 & 70 & 50 & 50 & 79 & 22.8 \\
**2** & 100 & 100 & 100 & 80 & 60 & 30 & 30 & 71 & 31.8 \\
**3** & 100 & 95 & 95 & 75 & 55 & 25 & 20 & 66 & 33.8 \\
**4** & 95 & 90 & 90 & 70 & 50 & 15 & 10 & 60 & 35.9 \\
**5** & 90 & 80 & 80 & 60 & 35 & 10 & 0 & 51 & 36.1 \\
**6** & 90 & 80 & 80 & 55 & 30 & 5 & 0 & 49 & 37.3 \\
**7** & 90 & 80 & 80 & 45 & 15 & 0 & 0 & 44 & 39.6 \\
**Mean** & 95 & 89 & 89 & 67 & 45 & 19 & 16 & & \\
**Standard deviation** & 5.0 & 9.3 & 9.3 & 14.4 & 19.1 & 17.2 & 19.0 & & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Recognition rates for the number of stock items and tag recognition intervals (%).  
Figure 7: Main effect plot for the recognition rate between the number of stock items and the tag recognition intervals.  
for obtaining the best recognition rate. Meanwhile, the tag recognition speed of the RFID reader was approximately 0.36 m/s. We performed inventory location identification with 20 replications by applying the proposed algorithm under the same settings and conditions. The accuracy of the location identification was calculated via comparing the experimental results with the actual location of the stock items in favor of the number of existing stock items divided by the total number of identified items. The results of the 20 repeated measurements under the same setting and conditions are shown in Figure 8. In Figure 8a, we could recognize that there were several incorrectly identified items in the 2 nd, 3 rd, 4 th, 5 th, 9 th, and 13 th measurements out of a total of 60 items. In Figure 8b, we can ascertain that the location identification success rate using the proposed algorithm was 98.75% on average, with a standard deviation of 2.22%, which is practically high enough to identify inventory locations using the passive RFID tag. Although the recognition rate hardly reaches 100%, a meaningful result was obtained, given that the conventional active RFID tag-based location awareness method is also unable to guarantee an identification accuracy of 100%. SME managers might consider applying the proposed method, as it is an economical alternative, instead of the active tag-based location awareness method. The market prices for active tags are typically known to be twice as high as that of the passive tag.