## 3 Results
### Trends of Major Academic Branches
#### 3.2.1 Identifying Research Trends with the Bibliometric Characterization  
The time-trend analysis among four branches is displayed in this subsection. Trends about publication outputs and citations in design research are listed in Figures 3 and 4. Firstly, an obvious rise can also be seen in the annual publication output related to interaction design. There is no doubt that the popularity of the Internet motivates the rapid development of interaction design. The value of CF grows until 2009, revealing that interaction design has shown tremendous growth. After 2009, it keeps flat without two local minima near 2010 and 2013. This indicates continued development of interaction design. Secondly, it also appears that the annual publication output of the traditional branch, product design, has grown steadily. The value of the CF of product design grows until 2015. However, there are temporary drops of the values between 2009 and 2010 and between 2013 and 2014, understood as temporary interruptions in the development of product design. Thirdly sometimes the annual publication output of ergonomic design slightly increases, and sometimes, it slightly decreases. Overall, it is growing. According to Figure 4, the value of CF grows at a steady rate, which indicates stable development of ergonomic design. Finally, the annual publication output of information design keeps increasing year by year. Nevertheless, the value of CF firstly increases and then decreases. Information design seems to become stagnant after 2009. Additionally, the topic evolution and citations of main topics in each branch are computed to reflect the influence of each branch. In Figures 5-12, we can learn that the influence of each branch increases yearly. As can be observed from Figures 5 and 6, Topic 9 is ascending with a rapid growth, while Topic 7 and Topic 19 keep up with and surpass Topic 9. The tendency reveals that ergonomic design is concerned with the scientific study of products and the environment, to be safe, healthy and comfortable for human beings. As shown in Figures 7 and 8, three main topics alternately increase, and Topic 3 keeps expanding rapidly. It shows that product design tends to be focused on developing the understanding of the design process. By comparing Figures 9 and 10, Topic 21 keeps its predominance, and Topic 1 intends to catch up. This indicates that research about the interaction of social media is a global trend in interaction design. According to Figures 11 and 12, Topic 14 maintains a competitive advantage with a slight drop, and Topic 0 has grown rapidly. It elaborates that information design presents how data are processed and what data you see. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Branch** & **TP** & **TC** & **ACPP** & \multicolumn{2}{c}{**CDS**} \\ \hline \multirow{2}{*}{Interaction design} & \multirow{2}{*}{7272} & \multirow{2}{*}{71,482} & \multirow{2}{*}{9.83} & \multicolumn{2}{c}{Ergonomic} & \multicolumn{2}{c}{Product} & \multicolumn{2}{c}{Information} \\ \cline{5-5}  & & & & 1091 & 1874 & 10,200 \\ \hline \multirow{2}{*}{Ergonomics design} & \multirow{2}{*}{5293} & \multirow{2}{*}{46,368} & \multirow{2}{*}{8.76} & Interaction & Product & Information \\ \cline{5-5}  & & & & 12,084 & 4002 & 8291 \\ \hline \multirow{2}{*}{Product design} & \multirow{2}{*}{2617} & \multirow{2}{*}{22,076} & \multirow{2}{*}{8.44} & Interaction & Ergonomic & Information \\ \cline{5-5}  & & & & 4911 & 14,044 & 3167 \\ \hline \multirow{2}{*}{Information design} & \multirow{2}{*}{5112} & \multirow{2}{*}{44,750} & \multirow{2}{*}{8.12} & Interaction & Ergonomic & Product \\ \cline{5-5}  & & & & 19,793 & 1454 & 2612 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Research outputs of major academic branches. Figure 4: Trend of the Citation Function (CF) in design research. Figure 5: The main topics’ evolution in ergonomic design. Figure 3: Publication outputs of major academic branches in design research. Figure 8: The citations of the main topics in product design.