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Top1. Introduction
Technologies applied to automobiles have grown proportionally to the advances in the automobile industry, and they have become universal and popular with the development of the industry. Accordingly, the consumption of vehicles has steadily increased, and various vehicle models have been developed to meet the demands of various consumers. The variety of vehicle models has developed into multi-purpose recreation vehicles that have the benefits of each vehicle model as related studies have actively been conducted. Multi-purpose recreation vehicles put emphasis on convenience and safety, and include various types of seats that can variably change the interior space. Most of the people who purchased mention the availability of the large interior space as a selection criterion, and there are containment seats among foldable rear seats for space utilization (Baltas, & Saridakis, 2013).
Among the containment seats, there is an infant pop-up seat, which is applied to the rear seats in the 2nd and 3rd rows, and it has the same function as the booster seat. The booster seat was applied in accordance with the regulations related to child boarding. According to the regulations of the National Highway Traffic Safety Administration (NHTSA) in the United States, children aged between 2 and 12 years are required to be seated on booster seats when they get on vehicles. Therefore, booster seats are essential elements in the rear seats of vehicles (Lee et al., 2019). Booster seats, which are seats for children, serve to correct the seating positions of children aboard in rear seats.
Thus, booster seats must be used. Infant pop-up seats combined with rear seats, which have the same function as booster seats that can prevent the injuries of infants or children, have already been applied to some vehicles (Asbridge et al., 2018). Unlike booster seats, infant pop-up seats can be used by both children and adults when their shapes are changed, but a design method that can satisfy the seat frame evaluation strength is required. In addition, there is a need for a way to reduce the weight of the seat frame while satisfying the strength of the seat frame.
In a study on optimizing the seat frame or seat component to which the optimization method was applied, Kim et al. (2014) and Kim et al. (2016) applied high-strength steel (HSS), which has higher strength than general steel, to compare the stiffness according to the thickness of the seat frame. Jeon et al. (2017) and Ju et al. (2017) proposed an optimization method by performing optimization according to the shape, material, and thickness of the seat frame and headrest module using design of experiments (D.O.E). Song et al. (2017) and Shin et al. (2018) proposed a method for the optimization of the structure combined with the seat cushion and cushion frame using an optimization technique for strength improvement and weight reduction. In addition to the seat frame, studies have been conducted to optimize the structure of the structure. Yang et al. (2016) and Oh et al. (2017) and Na et al. (2017) proposed a design method by performing topology optimization or size optimization to reduce the weight of the parts associated with the vehicle. In addition, Ju et al. (2019), in order to suggest a design method that can improve the strength of the vehicle seat frame, it has been confirmed that the strength is improved and the weight reduction is possible by using the structural analysis and optimization method applying dissimilar materials.