## 4 Experiment Results and Discussion
### Experiment Results
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Posture** & **Statistic** & \(\theta_{1}\) & \(\theta_{2}\) & \(\theta_{3}\) & \(\theta_{4}\) \\ \hline \multirow{4}{*}{Good posture} & Mean & 79.6379 & 95.6220 & 100.3043 & 86.9680 \\  & Min & 68.1986 & 78.6901 & 78.6901 & 78.9390 \\  & Max & 90.0000 & 111.8014 & 123.6901 & 97.2055 \\  & Std * & 6.0945 & 5.4683 & 8.0231 & 3.9771 \\ \hline \multirow{4}{*}{Text neck posture} & Mean & 56.1264 & 79.4418 & 86.1497 & 66.7944 \\  & Min & 30.9638 & 59.0362 & 56.3099 & 46.5310 \\ \cline{1-1}  & Max & 68.1986 & 99.4623 & 111.8014 & 79.1811 \\ \cline{1-1}  & Std * & 8.2535 & 7.1435 & 9.1617 & 6.2142 \\ \hline \multirow{4}{*}{L-posture} & Mean & 93.6963 & 118.1552 & 126.6295 & 105.1747 \\  & Min & 68.1986 & 105.9454 & 111.8014 & 88.4249 \\ \cline{1-1}  & Max & 111.8014 & 135.0000 & 143.1301 & 119.0199 \\ \cline{1-1}  & Std * & 8.7177 & 6.1626 & 8.2590 & 5.4857 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Statistic of mean, minimum, maximum, and standard deviation for each posture. We conducted a comparative experiment to assess whether conventional research methods can classify and measure good posture, text neck posture, and L-posture. We conducted a comparative experimental study using a posture measurement method that uses three-axis sensors [6] and a posture measurement method that uses a sensor cushion [20] that were recently published. Additionally, we performed the experiment using equipment that has similar functionalities to the devices proposed in previous studies. In the posture measurement study [6] using three-axis sensors, research was conducted to classify good posture and text neck posture in conventional research. Therefore, we performed an experiment to investigate whether this method could also measure L-posture. As shown in Figure 9, three-axis accelerometer sensors were attached next to the ear and at the back of the neck. And then, the x-axis, y-axis, and z-axis measurements were taken using the sensors when in good posture and L-posture. According to the experimental results, as observed in Table 3, the average sensor measurements next to the ear were similar between good posture and L-posture. Furthermore, the average sensor measurements at the back of the neck were similar between good posture and L-posture, excluding the y-axis value. In conclusion, since there were no significant differences observed when measuring using three-axis accelerometer sensors, it was challenging to classify between good posture and L-posture. Next, we conducted an experiment utilizing a sensor cushion, as shown in Figure 10, to classify postures [20]. Since the conventional study focused on classifying good posture, tilted posture, L-posture, and crossed-leg posture, we conducted an experiment in this study to investigate whether this method could be used to classify text neck posture as well. Figure 10a represents a good posture, while Figure 10b shows the corresponding results obtained from the sensor cushion. Figure 10c shows a text neck posture, while Figure 10d illustrates the corresponding results obtained from the sensor cushion. In the sensor cushion results shown in Figure 10b, d, areas with higher pressure are represented in red color. As shown in Figure 10b, d, both results show that the highlighted areas of the sensor cushion, represented by the red color, are concentrated in the central region. This indicates that in both postures, pressure was predominantly applied to the central region of the cushion. This result indicates that the conventional research method faces challenges in classifying between good posture and text neck posture. Therefore, through the experiments, it was evident that both of the existing studies had limitations in classifying text neck posture and L-posture, which are incorrect postures of the neck and spine. Figure 8: Examples of misclassified results: (**a**) result predicting good posture as text neck posture-1; (**b**) result predicting good posture as text neck posture-2.