## 3 Results
### Geographic Distribution of Research Output  
Table 2 presents the global distribution of contributions in the \"VRUs safety wearable technology\" research field, systematically recording each country's publication volume, centrality index, and year of first participation. The United States ranks first with 16 publications and a high centrality index of 0.32, establishing its leading position in the field since 2000. Despite entering the research field as late as 2016, China (People's Republic of China, including Taiwan region data, labeled as \"PEOPLES R CHINA\" in Figure 4) has rapidly risen to become the second-largest contributing country with 11 publications, demonstrating strong research momentum and ability to integrate into the global network. Germany, as the main research force in the European region, has accumulated eight publications since its participation in 2013. South Korea and Austria, although joining the field relatively late in 2017 and 2020, respectively, have already contributed five and four publications, reflecting these countries' growing research investment in VRU safety wearable technology. India's contribution is particularly significant; despite having only four publications, its centrality index of 0.08 indicates its research occupies an important strategic position in the knowledge network. The participation of Japan, France, Australia, and Malaysia has enriched the international research landscape in this field. Notably, although the United Kingdom is not listed in the top 10, its three constituent regions (England, Scotland, and Northern Ireland) have collectively contributed three research publications, beginning their participation in this field in 2019 and 2021, respectively. Figure 4 presents a global collaboration network map of VRU safety wearable technology research, precisely capturing the dynamic patterns of transnational academic exchange. This visualization intuitively displays the structural relationships and collaboration intensity of the international research community through multidimensional indicators such as node size, color intensity, and connection thickness. The United States is positioned at the network's core, with the largest node volume and a vibrant gradient coloration, highlighting its central position and radiating influence as a leader in this field. China, as a significant research force, features a substantial node size with prominent red intensity, while its notable connection with South Korea highlights the substantial collaborative relationship established between the two countries in this field, forming an East Asian regional research alliance. Multiple Eurasian countries form secondary research clusters around the core, with Germany, Austria, India, France, and Japan constituting key pillars of the global knowledge network. UK research appears as three independent geographical units in the network, each developing unique international cooperation pathways. The network periphery consists of the UAE, Australia, and multiple European and South American countries, forming a complete puzzle of the global research ecosystem. The node color \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No.** & **Publications** & **Centrality** & **Year** & **Country or Region** \\ \hline
1 & 16 & 0.32 & 2000 & USA \\
2 & 11 & 0.08 & 2016 & CHINA \\
3 & 8 & 0.00 & 2013 & GERMANY \\
4 & 5 & 0.00 & 2017 & SOUTH KOREA \\
5 & 4 & 0.00 & 2020 & AUSTRIA \\
6 & 4 & 0.00 & 2016 & JAPAN \\
7 & 4 & 0.08 & 2015 & INDIA \\
8 & 3 & 0.00 & 2017 & FRANCE \\
9 & 2 & 0.00 & 2023 & AUSTRALIA \\
10 & 2 & 0.00 & 2013 & MALAYSIA \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Global research output and centrality in VRU safety wearable technology by countries and regions. spectrum from purple to red maps the chronological sequence of countries joining this field, while the distribution density and thickness of connections precisely quantify the frequency and depth of academic exchanges.