## 4 Implementation of the AR System  
We implemented a real-time augmented reality physics simulator by combining the components described above. Through the implemented simulator, we simulated various objects with unique material properties. Our simulation models were generated by volume mesh model with sphere and torus shape using tetgen, a mesh generator. The following Table 4 shows the result of the wireframe rendering of volume mesh generated through tetgen [21]:  
In this research, the generated mesh models were simulated with a soft body simulator, and combined with an image system based on kinect v2 for augmented reality. First, we combined the real-time video stream with the soft body simulator for that. The following Figure 10 shows the combined result of kinect V2 and our soft body simulator: \begin{table}
\begin{tabular}{c c} \hline \hline
**Information** & **Wireframe Rendering** \\ \hline
**SPHERE** & \\ \hline NODE & 1.3 K \\ FACE & 2.1 K \\ SPRING & 25 K \\
**TORUS** & \\ NODE & 2 K \\ FACE & 1.4 K \\ SPRING & 62 K \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Result of Generate Volume Mesh Model. \begin{table}
\begin{tabular}{c c} \hline \hline
**NAME** & **DESCRIPTION** \\ \hline CPU & Intel i7 7700 3.60 GHz: 8 Core \\ GPU & Nvidia GeForce GTX 1080 Ti \\ RAM & 32 GB \\ V-RAM & 11 GB \\ Library & OpenGL GLSL 4.3, OpenCV 2.4.9, Kinect V2 \\ IDE & Visual Studio 2013 Ultimate \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Development Environment (Real-Time Physics Simulator). Second, we created several objects with various material properties, and experimented with changes in object motion through simulation. The properties of various objects are expressed through the changes of the constant (_Ks_) and damping (_Kd_) of the object. _Ks_ is information that indicates the rigidity of an object, and even if it has the same outer shape, the force to maintain its shape becomes close to a rigid object when the value of _Ks_ is large. _Kd_ is the damping ratio that represents the attenuation of the force that causes the deformation of the object, which causes the object to stop, without moving forever. We also added frictional forces to the environment, to allow for more realistic movements to our system. The following Figure 11 shows the simulation results of different objects implemented through our system. We conducted an experiment, scene 1, that identifies differences in simulation results by applying different material properties, and an experiment, scene 2, that identifies differences in simulation results by applying different external forces. We applied a water balloon, soccer ball, and bowling ball material to the sphere model by adjusting the material properties of each object. As a result of performing scene 1, we can see that the result of the simulation changes when different material properties are applied. The results of experiment 2 confirm that the deformation and the behavior of the object are different when different external forces are applied to the object having the same material properties. We applied external forces to the top of each of the three balls, and we compared the ball bouncing off the invisible wall. In the case of a stronger external force, the simulation was performed at high speed and the deformation was greater. Each snapshot in Figure 12 was taken every 1000 frames. Finally, we conducted a survey to provide simulators to 10 students to teach physics, and to verify the educational effectiveness and responsiveness of the proposed system. Table 5 shows the items of our survey. We provided a total of five multiple-choice questions and two short-answer questions, and all students responded to the questionnaire [22]. Figure 11: Result of Simulation Scene 1 (Freefall Simulation: Sphere and Torus Model). Figure 10: Combined Result of Kinect Video Stream and Our Soft Body Simulator. The results of the survey's multiple-choice question are shown in the Figure 13.  
Q1 and Q2 were answered most positively.