# Application of Quality Function Deployment for Product Design Concept Selection
## 4 Results
### Results of Evaluating Concept Competitiveness by the QFD-AHP  
To evaluate the concept competitiveness, we considered multiple criteria in advance. Specifically, we selected five key criteria which represent the CR in the QFD: heat-exchange performance (kcal/h), air pressure drops (mm\({}_{\text{Ag}}\)), refrigerant pressure drops (kg\({}_{\text{f}}\)/cm\({}^{2}\)), weight, and cost. As depicted in Figure 3 by [PERSON], [PERSON], [PERSON], and [PERSON] [49], air travels through the core and refrigerant passes through several holes in the tubes to exchange the heat between the hot air and the cold refrigerant. The heat-exchange performance (HEX) measures how much energy (kcal) has been exchanged during one hour. If we increase the HEX using the same size, we can reduce the size of the product. The air pressure drops (d\({}_{\text{P}}\) air) means the pressure difference between the inlet and outlet of the evaporator. If the d\({}_{\text{P}}\) air increases, air flow decreases which makes noise. The refrigerant pressure drops (d\({}_{\text{P}}\) ref) represents the pressure difference between the inlet and outlet of the tubes. As d\({}_{\text{P}}\) ref increases, the efficiency of the A/C  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{6}{c}{**Engineering Specifications (I,3,5)**} \\ \hline  & & \begin{tabular}{c} **Customer** \\ **Weights** \\ **(I,3,5)** \\ \end{tabular}  & \begin{tabular}{c} **Number** \\ **of Components** \\ \end{tabular}  & \begin{tabular}{c} **Product** \\ **Width** \\ \end{tabular}  & \begin{tabular}{c} **Product** \\ **Height** \\ \end{tabular}  & \begin{tabular}{c} **Product** \\ **Thek-ness** \\ \end{tabular}  & \begin{tabular}{c} **Number** \\ **of** \\ **Tubes** \\ \end{tabular}  & \begin{tabular}{c} **Unit** \\ **NoPHP** \\ **Volume** \\ \end{tabular}  & \begin{tabular}{c} **Unit** \\ **\(\omega\)** \\ \end{tabular}  & \begin{tabular}{c} **Unit** \\ **Fin Vol.** \\ **ume** \\ \end{tabular}  & \begin{tabular}{c} **Unit** \\ **\(\omega\)** \\ \end{tabular}  \\ \hline \multirow{7}{*}{\ \begin{tabular}{c} Customer \\ requirements \\ \end{tabular}  } &
\begin{tabular}{c} Smaller size maintaining the \\ same heat-exchange. \\ Silent operation and no noise. \\ Good operational efficiency. \\ Low weight for fuel efficiency. \\ Low price \\ Low price \\ Low price \\ Relative weights \\ Unit \\ Unit \\ Current design \\ Competi  
system decreases. The weight of the component is a critical factor and is highly related to the fuel efficiency of the vehicle. The cost, which refers to the numerous expenses required to produce the product, is also crucial for buyers and directly affects market price. After selecting five criteria, we conducted a pair-wise comparison to determine the weighted value of each criterion. We used a nine-point Likert scale to evaluate concept competitiveness as shown in Table 3. We developed the rating levels through interviewing the firm's internal experts. Value it in Equation (7) represents the relative result compared to the current product design. The V\({}_{\text{current}}\) denotes the current product design's value and V\({}_{\text{new}}\) denotes the new design concept's value. For example, cost decreases, the cost competitiveness increases. If the new concept's cost is five percent (t = \(-5\)) less than the current design, we rate the new concept equal to 7. To calculate the value t, we used the bench test results of the current design and competitors. As we did not have actual components of the new concepts, we adopted the estimated results from product designers. The costs were estimated by cost estimators under the same calculation toolkit. \[\text{t}=100\times(\text{V}_{\text{new}}-\text{V}_{\text{current}})/\text{V}_{ \text{current}} \tag{7}\]  
We calculated the concept competitiveness scores by multiplying the rating scores by the weighted values. Then, we normalized the scores by dividing each original score by the current product's score.