## 3 Results
### Quantitative Assessment of AML Accuracy in Meeting Korean Depth and Positioning Regulations  
In South Korea, the regulatory standards for underground utility detection require a minimum detection depth of 3 m and mandate that both horizontal (position) and vertical (depth) deviations remain within \(\pm\)0.30 m for metallic and non-metallic pipelines. To assess the compliance of the All Materials Locator (AML) system with these standards, field observations were collected across 32 samples, each containing 10 measurement points for both RCP (Reinforced Concrete Pipe) and PE (polyethylene) conduits.  
The deviation values were derived by subtracting the standard reference values presented in Table 1 (see Section 3.1) from the actual measured values. Each measurement yielded four types of deviation values per point: \(\Delta\)RCP Position, \(\Delta\)RCP Depth, \(\Delta\)PE Position, and \(\Delta\)PE Depth. These were then aggregated across all 10 points and summarized for each sample.  
Across the full dataset (32 samples \(\times\) 10 points), the AML system demonstrated consistently high accuracy. The average horizontal deviation for RCP pipelines was +0.0161 m, with a standard deviation of \(\pm\)0.0584 m, while the vertical deviation averaged +0.0822 m, with a standard deviation of \(\pm\)0.1213 m. For PE pipelines, the average horizontal deviation was +0.0029 m (SD \(\pm\) 0.0619 m), and the average vertical deviation was +0.0975 m (SD \(\pm\) 0.1154 m). All deviation values fell within the allowable \(\pm\)0.30 m margin.  
To highlight the variability among different samples and points, Table 2 shows paired deviation values from selected samples. This compact representation underscores the range of AML measurements and supports the broader statistical trends.  
In addition, Figure 8 presents heatmaps of the horizontal and vertical deviations for both RCP and PE pipelines across all 32 samples and 10 measurement points. These visualizations provide a spatial overview of the AML system's performance, with color gradients centered around zero to emphasize deviation magnitudes and directionality. The consistent color distributions observed in all four heatmaps support the statistical findings and visually confirm the stability, symmetry, and reliability of the AML measurements across different material types and measurement conditions.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**No.** & \(\Delta\)**RCP Position (m)** & \(\Delta\)**RCP Depth (m)** & \(\Delta\)**PE Position (m)** & \(\Delta\)**PE Depth (m)** \\ \hline
1 & \(-\)0.001/0.002 & \(-\)0.006/\(-\)0.086 & 0.031/0.001 & \(-\)0.274/\(-\)0.314 \\
2 & 0.032/0.013 & 0.037/\(-\)0.023 & \(-\)0.017/\(-\)0.007 & \(-\)0.395/\(-\)0.315 \\ ⋮ & ⋮ & ⋮ & ⋮ & ⋮ \\
10 & \(-\)0.058/\(-\)0.068 & 0.08/0.2 & \(-\)0.014/\(-\)0.014 & 0.057/0.167 \\ \hline \end{tabular}
\end{table}
Table 2: Paired deviation values across selected samples for RCP and PE pipelines. Each cell shows the deviation values (in meters) of 2 representative samples among the 32 total samples, illustrating variation in AML measurement performance across different pipeline types and depths.  
These results confirm that the AML system successfully satisfies the regulatory requirements in both depth and positioning for non-metallic pipeline detection. While minor fluctuations were observed due to differences in soil moisture, pipe material, and depth, the deviations remained well below the regulatory thresholds. The device also showed robust repeatability across varied field conditions, indicating its suitability for field deployment in compliance-critical applications such as utility mapping, excavation safety, and public infrastructure monitoring.