## 4 Experiments and Result
### Proposed System Development Environment  
The extension of the paper manual to an immersive education system based on virtual reality is proposed as a method of convergence education that enables theoretical and practical education. The proposed system consists of functions suitable for technical training, such as an aircraft maintenance simulation, as follows:  
* Scenario-modeling-based virtual environment: The virtual environment is built with scenario modeling for procedural training. To advance to the convergence education of theory and practice, we implemented a central button-type sharing board as a tool for theory education. Sharing boards allow all users to review procedures and equipment descriptions together.
* Network configuration for multi-user access: The proposed system forms a virtual classroom where experts and beginners can train through a network. Users can communicate and collaborate in a virtual environment implemented like a workplace.
* User interaction: Regardless of their physical location, all users can connect to the virtual space to interact with other users. Users can also access objects in the virtual  
Figure 3: Demo test procedure.  
environment simply by pressing a button. Training scenarios and explanations of parts and equipment are provided as TTS, therefore, beginners can learn on their own.  
The aircraft maintenance simulation used in the experiment consists of the procedure illustrated in Figure 5. All three users wore VR devices and played the proposed system. Before entering the room, a TTS-guided overview of the simulation and an introduction to the aircraft are provided to the user. The user confirms the description and then proceeds to the next step. Given that separate rooms were not required in this simulation, users were switched directly to the simulation screen. The transition process for the simulation consists of a loading scene. When users enter the simulation, they can meet users who are logged in at the same time. Users can communicate and interact with each other and use virtual objects directly. During the development process, we reflected on the feedback received from the demo tests. First, considering the overlap between TTS and other users' voices, a rough outline and explanation were provided with TTS in the first scene. We also developed a button-based system of interacting for direct interaction.  
Area A contains explanations for each aircraft maintenance procedure, serving as a kind of guide that contains the contents of this simulation step. As each step contains the contents of a different procedure, the explanations in Area A also change with each step. Area B contains descriptions of the tools and parts that correspond to the contents described in Area A. To the left of Area B are three circular toggle buttons, each with a description. From top to bottom, the first button displays a 2D image guide for each part. As well, the positions of the parts processed in each step are marked and displayed. The  
Figure 4: Aircraft maintenance simulation using the proposed system.  
Figure 5: Aircraft maintenance simulation configuration.  
second button uses both 3D models and text to provide a description of the tools to be used in each step. The third button has a similar function to the second, but instead describes the parts to be used. Area C displays a 3D model of the aircraft and a button at the bottom. Any parts emphasized in the description of Area A are outlined in green. Users can interact with the aircraft directly or with a button. All changes in each area are synchronized in real-time and delivered to all users.  
Figure 6 shows the sharing board interface of the aircraft maintenance simulation. Users can interact with areas A, B, and C.