## 4 Conclusions  
In this study, using the normalized perforated area, the bulletproof performance of eco-friendly Hanji-cornstarch biocomposites was analyzed with different numbers of Hanji layers and various thicknesses of cornstarch suspension layers. FEA simulations were conducted for analyzing the bulletproof performance of the Hanji and cornstarch layers. The results showed that the linear velocity of the bullet decreased with increases in the thicknesses of both the Hanji and cornstarch layers. The normalized perforated area of the Hanji-cornstarch composites decreased with increases in the thickness of the cornstarch layers, while it gradually increased when increasing the number of Hanji layers without cornstarch suspension layers. This is because the perforated area on the witness clay piece was mainly influenced by the stress momentum, which was propagated by the bullet impact on the bulletproof plate rather than the bullet momentum. The stress momentum increased with an increase in both the number of Hanji layers and the thickness of the cornstarch layers, but the stress momentum in the Hanji layers was a lot greater in comparison with the stress momentum in the cornstarch layers. We inferred that the bulletproof performance of Hanji-cornstarch composites was influenced significantly by the both bullet momentum and the stress momentum. Accordingly, we fabricated bulletproof biocomposites using cost-effective and easily fabrication process compared to previous papers using Kevlar. The findings of this work would be beneficial to the munitions industry owing to the facile and cost-effective manufacturing process used and favorable bulletproof performance of the Hanji-cornstarch biocomposites. Based on the results of this study, developing thin biocomposite-based bulletproof plates will be beneficial to enhance the mobility of armors as the future work. **Supplementary Materials:** The following are available online at [[http://www.mdpi.com/2076-3417/10/1/88/s1](http://www.mdpi.com/2076-3417/10/1/88/s1)]([http://www.mdpi.com/2076-3417/10/1/88/s1](http://www.mdpi.com/2076-3417/10/1/88/s1)), Figure S1. Fabrication of bulletproof composite plates using LbL method: (**a**) Assembling the Hanji layers by applying adhesive, (**b**) Cornstarch suspension stored in the zipper bag, and (**c**) composite plate formed by LbL of Hanji and applying cornstarch suspension, Figure S2 Comparison of (**a**) commercially available 9-mm bullet and (**b**) 9-mm bullet modeled in this study, Figure S3, Actual images obtained during bulletproof experiments for (**a**) composite with 20-mm-thick cornstarch suspension layers and 60 sheets of Hanji and (**b**) composite with no cornstarch layers and 120 Hanji layers, Figure S4. (**a**) Perforated diameter of clay after bulletproof experiments using composites with various Hanji layer sheets and (**b**) perforated diameter of clay after bulletproof experiments using hybrid composites composed of Hanji (60 sheets) and various thickness of cornstarch suspension (STF) layers, Figure S5. Nodes on the 40 mm x40 mm region of the plate as viewed from the (**a**) side and (**b**) bottom, Table S1. Mechanical properties of Hanji and cornstarch suspension, Built-in function in ABAQUS/CAE  
**Author Contributions:** Conceptualization, H.C., J.L., S.H., and S.K. ; Experiments, H.C., J.L., and S.H. ; Simulation, J.L. ; Formal analysis, H.C. and J.L. ; Investigation, H.C.; Writing-original draft, H.C., J.L., and S.H. ; Writing-review, S.K. ; Supervision, S.K. All authors have read and agreed to the published version of the manuscript. **Funding:** This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) [grant number NRF-2018R1C1B6002339] and the Chung-Ang University Research Scholarship Grants in 2019. **Conflicts of Interest:** The authors declare no conflict of interest. Figure 7: Stress momentum for various thicknesses of (**a**) Hanji layers and (**b**) cornstarch layers.