## 2 Materials and Methods
### Technology Acceptance Model  
The unified theory of acceptance and use of technology (UTAUT) [25] is applicable for identifying the key factors that influence behavioral intention to use. The objective of the UTAUT is to support management by providing a useful tool to assess the success of new technology introductions and understand the drivers of user acceptance, thereby enabling them to design interventions targeted at populations of users that may be less inclined to adopt and use new systems. The UTAUT framework was modified, as shown in Figure 1, by adding a bridge visual defect quality inspection (VIS) factor that was designed though group interviews with ten lead users from Thailand's Department of Highways. VIS influences the performance expectancy (PER), effort expectancy (EFF), and social influence (SOC) of UTAUT, and leads to a behavioral intention to use (BEH). Additionally, VIS consists of an image acquisition to capture the bridge and identify defects (VIS1), environment setup (VIS2), bridge defect information assistance (VIS3), and bridge history information (VIS4). After the user acceptance framework was developed, a correlation analysis based on a quantitative analysis involving 400 questionnaires was performed to confirm the validity of previously identified factors, and to gather information to build a user-driven mobile application. This analysis identified only VIS-PER-BEH and VIS-EFF-BEH to be significant (Table 1). VIS-SOC-BEH was not significant, suggesting that a user's behavioral intention relies on personal factors and not from social influence. The analysis also determined that VIS affects PER the most and that PER has the biggest impact on BEH. In other words, user intention occurs once users try the product themselves, and not when other people in an organization convince them to use it. This suggests that allowing the user to test the product in a free trial could be an effective strategy. Additionally, user intention to trial the product is more likely to occur if they recognize that the product helps them improve their work performance. This also suggests that product features that include image acquisition to capture the bridge and identify defects (VIS1), environment setup assistance (VIS2), bridge defect information assistance (VIS3), and bridge history information (VIS4), can assist user collaboration and inspection issues explicitly. After all factors are confirmed, they are taken into account to design the user experience and user interface (UXUI) of the mobile application.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Factor**} & \multirow{2}{*}{**Hypothesis**} & \multirow{2}{*}{**df**} & \multicolumn{2}{c}{**Mean**} & \multirow{2}{*}{**SD**} & \multirow{2}{*}{**F**} & \multirow{2}{*}{**Sig.**} \\  & & & & & & \\ \hline VIS \textgreater{} PER & H1 & 39 & 0.473 & 0.464 & 2.529 & 0.000* \\ VIS \textgreater{} EFF & H2 & 39 & 0.337 & 0.462 & 1.688 & 0.008* \\ VIS \textgreater{} SOC & H3 & 39 & 0.416 & 0.525 & 1.598 & 0.016* \\ PER \textgreater{} BEH & H4 & 8 & 0.593 & 0.520 & 5.036 & 0.000* \\ EFF \textgreater{} BEH & H5 & 10 & 0.466 & 0.520 & 3.960 & 0.000* \\ SOC \textgreater{} BEH & H6 & 11 & 0.113 & 0.520 & 0.962 & 0.482 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Technology acceptance model framework results.  
Figure 1: Technology acceptance model using modified UTAUT with VIS factor.