## 3 Results
### Full Network Adjustment of 5560 Unified Control Points (2008-2021)  
To implement a consistent and accurate adjustment of South Korea's nationwide unified geodetic control network, approximately 17,000 RINEX files and 17 domestic continuously operating reference stations (CORS) were used to construct a comprehensive geodetic solution. The GNSS observation data spanned the years 2008 to 2021, and baseline processing was performed on a yearly basis to account for variations in installation schedules and field operations. Unlike previous network adjustment strategies, which relied on four or five locally selected fixed stations per region, the present study adopted a unified adjustment approach using 17 nationally distributed and rigorously verified fixed stations. This strategy--justified by the findings in Section 3.2--ensures superior consistency across space and time, enabling the generation of reliable coordinates free from localized bias or procedural inconsistencies. Prior to baseline processing, metadata files were prepared to ensure proper modeling of observation geometry and station attributes. The site.apr file defined approximate coordinates for all unified control points (UCPs), while the station.info file included information on observation dates, session durations, antenna types, receiver models, and radome codes. However, inconsistencies were present across the dataset. In many cases, receiver model names were missing, and some stations had incomplete or conflicting metadata. These issues were resolved through manual inspection and correction, with particular reliance on antenna model codes as identifying references. Significant discrepancies were also found in RINEX file naming conventions. According to national surveying regulations (revised 30 December 2020), observation files should follow the format: SITE (4 characters) + DOY (3 digits) + observation index (1 digit), and contain at least 4 h of continuous data (8 h for pre-2020 data). In practice, however, many sites had inconsistent naming--such as five-character station names or multiple short-duration files per day--resulting from field-level errors. To address this, automated \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**SITE** & **N** & **E** & **H** & **dN** & **dE** & **dH** \\ \hline UCP001 & 518,199.1056 & 202,524.8082 & 69.6456 & 0.0069 & 0.0011 & \(-\)0.0046 \\ UCP002 & 632,748.5197 & 300,213.5836 & 450.1037 & \(-\)0.0009 & 0.0027 & 0.0142 \\ UCP003 & 649,301.4179 & 326,825.3849 & 31.0333 & \(-\)0.0066 & \(-\)0.0060 & 0.0350 \\ UCP004 & 642,899.4686 & 327,998.3013 & 49.0462 & \(-\)0.0039 & \(-\)0.0057 & 0.0404 \\ UCP005 & 630,251.8133 & 320,260.1322 & 610.8182 & \(-\)0.0048 & \(-\)0.0068 & 0.0137 \\ \(\cdots\) & \(\cdots\) & \(\cdots\) & \(\cdots\) & \(\cdots\) & \(\cdots\) & \(\cdots\) \\  & & & Mean & 0.00073 & \(-\)0.0019 & 0.0190 \\  & & & STD & 0.0047 & 0.0035 & 0.0237 \\  & & & RMSE & 0.0047 & 0.0039 & 0.0304 \\  & & & Max. & 0.0123 & 0.0087 & 0.4566 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Sample results of pilot adjustment and statistical summary of coordinate differences for selected UCPs. preprocessing procedures were implemented. Station names exceeding four characters were standardized by removing the second character, and DOY values were reassigned based on RINEX header timestamps. With the dataset corrected and preprocessed, baseline analysis was performed using the GAMIT software for each year from 2008 to 2021. The output H-files served as input for GLOBK, through which the full network adjustment was conducted. The adjustment included all 5560 UCPs, anchored to the 17 fixed stations previously established in Section 3.1, which served as reference coordinates within the ITRF2014 framework. The spatial distribution of the 5560 UCPs included in the full network adjustment is presented in Figure 10. The map visualizes the nationwide coverage and regional density of the unified control network.