## 5 Case Study
### Application and Discussion  
We have developed a prototype system for elevator customized design based on Java and MySQL, as shown in Figure 7. This design platform has been applied in the elevator customization cooperated with Canny Elevator Co. Ltd. in China. There are  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Index**} & \multirow{2}{*}{**FR**} & \multirow{2}{*}{**Ground Truth**} & \multicolumn{4}{c}{**Predicted Values in Different Cases**} \\ \cline{3-6}  & & & **Case 1** & **Case 2** & **Case 3** & **Case 4** \\ \hline \(r_{1}\) & Hoisting motor power & 10 kW & & & 11 kW \\ \(r_{2}\) & Hoisting rope size & \(\phi\) 10 & & & \(\phi\) 10 \\ \(r_{3}\) & Gear of hoisting machine & Gearless & & & Gearless \\ \(r_{4}\) & Number of hoisting ropes & 2 & & 4 & \\ \(r_{5}\) & Number of passengers & 9 & & 8 & \\ \(r_{6}\) & Door opening & Front and rear opening & & & Front and rear opening \\ \(r_{7}\) & Number of stops & 15 & & & \\ \(r_{8}\) & Counterweight position & Side & Side & Side \\ \(r_{9}\) & Compensating device & Rope & & & Rope \\ \(r_{10}\) & Number of guides & 2 & & 2 & \\ \(r_{11}\) & Length of hoisting rope & 1219 & & 1188.4 & \\ \(r_{12}\) & Rated capacity & 900 kg & & 840 kg & \\ \(r_{13}\) & Speed & 4.1 m/s & 3.64 m/s & 3.64 m/s & \\ \(r_{14}\) & Car weight & 1053 & & & 972.4 \\ \(r_{15}\) & Car depth & 1328 & & & 1328 \\ \(r_{16}\) & Car width & 1534 & & 1570.6 & & \\ \(r_{17}\) & Car height & 2729 & & & 2795.8 \\ \(r_{18}\) & Shaft depth & 2076 & & 2130.3 & & 2119.3 \\ \(r_{19}\) & Shaft height & 43,086 & & & \\ \(r_{20}\) & Shaft width & 1997 & & & \\ \(r_{21}\) & Door width & 939 & & 1043.2 & 1024.9 \\ \(r_{22}\) & Door height & 2232 & 2070.4 & 2057.2 & \\ \(r_{23}\) & Door offset distance & 0 & & & \\ \(r_{24}\) & Machine room height & 1638 & & & \\ \(r_{25}\) & Headroom height & 3386 & & & 3974.2 \\ \(r_{26}\) & Pit depth & 4024 & & & 4845.2 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Predicted values of a new FR in elevator.  
four design stages in this design platform, as described in Section 1, and nine design tools in each design stage (Figure 7a). The proposed approach is packaged in the design tool, requirements forecast (Figure 7c), in the requirements modeling stage. In the real-world elevator customized design process, the design tool, requirements elicitation, captures customer requirements and outputs the incomplete CN to the requirements database. FR often has missing values due to incomplete CN, which effects the requirements conversion from FR to design parameters. Traditionally, managers fill in the missing values based on their own knowledge and experience. The imputation results may not fulfil individual customer requirements. After integrating the proposed approach in this design platform, managers can choose the order in the requirements database and view the missing parts in FR, and then automatically obtain the predicted results of the missing values, as shown in Figure 7c.  
By performance comparison in Section 5.2 and case analysis in Section 5.3, the predicted results are valuable and effective in the practical design process. The response time of the requirements prediction is less than two seconds, which is also acceptable to managers. The proposed approach is feasible in product customized design, with the following advantages: (1) avoiding managers manually filling in missing values of FR in the design process; (2) the predicted results are similar to the real personalized requirements; (3) this  
Figure 7: User interface of the developed customized product design platform.  
approach solves a potential problem in requirements modeling and can aid product design with rapid response ability.