A needleless automatic injection syringe (Jet Injector) is a device that delivers drugs into the skin and tissues using high-speed fluid jets without the use of injection needles. Jet Injector's core technology is to penetrate the stratum corneum of the skin by converting pressure energy generated in the driving unit into fluid kinetic energy, and structural loads and dynamic responses generated in this process directly affect the performance and durability of the device. Therefore, the structural mechanical design of the drive unit can be said to be a key factor in securing the reliability and injection accuracy of the Jet Injector. This paper is intended to provide the basis data for the basic design of the drive unit of the "Animal Vaccine-free Automatic Injection Syringe (hereinafter referred to as the "Jet Injector"), and this calculation data provides basic data for the design. Based on this, it is possible to design the drive unit according to various assumptions and given conditions, and the expected performance can be reasonably inferred according to the design.

In this study, the design of shock tower mounting, a type of shock absorber mounting for four-wheel drive vehicles, was addressed through structural analysis. In the case of existing shock tower mounting components, cracks occurred in the shock tower frame side weld joints, so the maximum stress should be reduced to extend the life of the designed components. Based on this, various design changes were performed on the shock tower mounting components, and the maximum stress generated through structural analysis of each design change model was compared. For the structural analysis, a load of 40,000 N was applied in the axial direction of the shock absorber, and the results were relatively analyzed and compared. As a result of the analysis of the shock tower mounting components through the design change, Case 3, a model that alleviated the stress concentration applied to the body mounting, increased the strength compared to the existing model, and the stress in the shock tower frame side weld joints was reduced by 16.3%.

In four-wheel-drive vehicle, improving traction with the road surface enhances the vehicle's ability to respond to various driving conditions, increasing its overall versatility. Consequently, various studies have been conducted on four-wheel-drive vehicles that support torque distribution through electronic control. The driving unit that operates the transfer case assists in smooth torque distribution by providing high torque. Therefore, this study developed a reduction mechanism by vertically arranging a planetary gear set in the driving unit to increase the reduction ratio. To achieve this, a common ring gear with 52 teeth was used, and the design included a first-stage planetary gear with a sun gear having 18 teeth, a planet gear with 17 teeth, a second-stage sun gear with 12 teeth, and a planet gear with 20 teeth. The corresponding tooth profiles and structures were also designed. Based on this, a transfer case drive reduction module was developed, which improved torque performance: the first-stage planetary gear system provides 4.23 kgf·m of torque, and the second-stage planetary gear system achieves a final torque of 5.98 kgf·m

In this study, the design of the lower arm, a type of suspension for a 4 wheel drive vehicle, was dealt with through structural analysis. In the case of the existing lower arm, cracks occurred in the neck, so it is necessary to reduce the maximum stress in order to extend the life of the analysis model. Based on this, various design changes were made, and the maximum stress generated was compared through structural analysis of each design change model. For structural analysis, a unit load (1N) was applied in the vertical direction to the lower arm model, and the results were analyzed relative to each other. As a result of analysis through various design changes, case 3, a model in which the stress concentration applied to the lower arm was relieved, showed an increase in strength of about 51% compared to the existing model.

In this study, we changed the existing S45C steel shafts applied to the drive shaft for power train of automotive to Al7003-T6 aluminum material. For this purpose, the optimal inner diameter of the aluminium shaft is established. And, analysis of the stresses and vibration characteristics of shafts were analyzed through finite element analysis. The final aluminum drive shaft was evaluated through the static torsional torque test and the frequency test. The Al7003-T6 aluminum drive shaft's weight is 67% comparing from 100% of shaft with existing steel, and with the performance of 3,276 N-m and 236 Hz, it satisfies requirements of the torsional torque of 3,000 N-m and vibration characteristic over 150 Hz required for drive shaft.