## 5 System Evaluation
### Case Study  
After the system setup stage, case studies related to construction hazard topics are developed for the iAPR prototype in order to evaluate the learning framework and the proposed system. A virtual high-rise building jobsite, which includes fourteen floors and a basement, was chosen for the construction hazard investigation. According to Occupational Health and Safety Administration (OSHA) statistic, \"Fatal Four\" [54] (falls, struck by object, electrocutions, and caught-in/between accidents) constitute the highest rate of construction accidents in a year, therefore hazard case studies related to \"Fatal Four\" are chosen for the iAPR trial system, which are summarized in Table 2.  
Firstly, the educators and learners log into the iAPR prototype through their own ID account, and then click on the HUM function (see Figure 2a) to start the hazard lesson. After that, the educator delivers online slides providing key hazards that often occur during high-rise building construction. With the educator's explanation and synthesis, the learners take part in \"question and answer\" activities with the educator and other learners until they thoroughly remember and understand all construction hazards in the lesson. Next, the learners log into the HRM function (see Figure 2b) to navigate a virtual high-rise building jobsite and investigate potential hazards. Following the educator's guidance, the learners inspect all hazard cases studies in a virtual construction site to acquire knowledge and skills. Finally, the learners play a testing simulation game using the SPM function (see Figure 2c) in order to assess their performance.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**No.** & **Fatal Four** & **Potential Hazards** & **Virtual Scenario** \\ \hline
1 & Falls & Fall from mobile scaffold & 1 st floor \\
2 & Falls & Fall from 2 nd floor to ground floor due to lack of guardrails & 2 nd floor \\
3 & Falls & Falling from temporary ladder during installation of ceiling panels & 3 rd floor \\
4 & Falls & Fall from stair due to lack of temporary handrails at the edge of floor & 5 th floor \\
5 & Falls & Fall from Boatswain’s chair due to lack of an independent lifeline & 11 th floor \\
6 & Falls & Fall into opening of stair at the 8 th floor due to lack of barriers & 8 th floor \\
7 & Struck by object & Struck-by falling object due to lack of safety nets & Roof \\
8 & Struck by object & Bricks falling from height on worker’s head without safety & 7 th floor \\
9 & Struck by object & Metal pipes falling on worker’s head during lifting operation & 9 th floor \\
10 & Electrocution & Electrocution when installing an air-conditioner & 10 th floor \\
11 & Electrocution & Electrocution when using hand tool & Basement \\
12 & Caught-in/between & Worker is trapped during lift maintenance & 12 th floor \\
13 & Caught-in/between & Worker is caught between a truck and concrete due to toppling over of precast concrete building unit & Ground floor \\ \hline \hline \end{tabular}
\end{table}
Table 2: Case studies for construction hazard investigation.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **iAPR Server** & **iAPR Client** \\ \hline Hardware & Raspberry Pi Model B & Laptops and PCs \\ OS & Linux & Windows \\ Software & KPano (application) \& mySQL (database) & Bult-in web browser \& NGRAIN software \\ Network & Ethernet link & Ethernet/WiFi access \\ \hline \hline \end{tabular}
\end{table}
Table 1: System prototype configuration.