## 4 Conclusions  
CAE prediction technology for compression behavior in multi-stacked packages is an important tool for preventing warehouse accidents, shortening packaging development periods, and optimizing packaging. In this study, compression and compressive creep behavior of target shipping containers, which are material properties based on FEA, and the lifetime and load-sharing rate, were analyzed to develop CAE prediction technology for predicting the multistage compression behavior of three target packages with different logistics conditions. The research results can be summarized as follows:  
1. The reduction rate of the compression strength of the container with respect to the increase in the relative humidity was greater in the 'horizontal long' container than in the'vertical long' container. However, the failure strain increased with increasing relative humidity in the'vertical long' container, but decreased in the 'horizontal long' container. A nonlinear regression model for the SS behavior of the target shipping container was developed for the relative humidity and strain.
2. Using a 12 h creep experiment on the target shipping containers, a nonlinear creep model was developed with the applied stress and elapsed time as factors of the model. The instantaneous elastic strain, retarded elastic creep, and steady-state creep rates increased as the load was applied and the relative humidity increased, and when the relative humidity at the same applied load increased.
3. Based on the data obtained from the 12 h creep strain experiment, the 12 h average creep rate (CR\({}_{12}\)) was analyzed using linear regression analysis, and the values were re-corrected until failure. As the applied load increased, the rate of increase in the average creep rate (CR\({}_{\text{FD}}\)) increased, i.e., the higher the applied load level, the larger the difference in the average creep rate with respect to the relative humidity.
4. The lifetime (time to failure) estimated from the failure strain and average creep rate of the container gradually decreased as the applied load increased at all values of relative humidity. However, as the applied load increased, the difference with respect to the relative humidity tended to decrease.  
Figure 8: Calculation of load-sharing rate from SS curves of the shipping container and EPS cushioning material.  
In the target packages used in this study, the ratio of the load-sharing rate between the shipping container and EPS cushioning material was determined to be 2%:98%, with most of the stacking load applied to the product through the cushioning material. Therefore, data on the compression and compressive creep behavior of the EPS-based cushioning system are considered significant in developing a CAE prediction technology for the compression behavior of multi-stacked target packages.  
Data curation, J.M.P. and H.M.J.; formal analysis, J.M.P.; funding acquisition, H.M.J.; investigation, G.Y.L. and D.H.K.; software, J.M.P. and H.M.J.; validation, J.M.P.; visualization, J.M.P.; writing--original draft, J.M.P. and H.M.J.; writing--review and editing, J.M.P., G.Y.L. and H.M.J.; supervision, H.M.J. All authors have read and agreed to the published version of the manuscript.  
This research was carried out with the support of Cooperative Research Program for development of data application technology for postharvest management of the agricultural and livestock product (Project No.: FJ017050042022), Rural Development Administration.  
Not applicable.  
The authors declare no conflict of interest.