Study Design. Analytical biomechanical study using a finiteelement (FE) model. Objective. We investigated the effects of paraspinal muscle volume to the physiological loading on the lower lumbar vertebral column using a FE model. Summary of Background Data. The FE model analysis can measure the physiological load on the lumbar vertebral column. Which changes as the surrounding environment changes. In this study, our FE model consisted of the sacrum, lumbar spine (L3-L5), intervertebral discs, facet joints, and paraspinal muscles. Methods. Three-dimensional FE models of healthy lumbar spinal units were reconstructed. The physiological loads exerted on the lumbar vertebra column were evaluated by applying different paraspinal muscle volumes (without muscles, 50%, 80%, and 100% of healthy muscle volume).Results. As the paraspinal muscle volume increased, the loads exerted on the vertebral column decreased. The mean load on the intervertebral disc was 1.42 AE 0.75 MPa in the model without muscle, 1.393 AE 0.73 MPa in the 50% muscle volume model, 1.367 AE 0.71 MPa in the 80% muscle volume model, and 1.362 AE 0.71 MPa in the 100% muscle volume model. The mean loads exerted on the posterior column of lumbar spine were 1 1 . 7 9 AE 4 . 7 0 M P a i n t h e m o d e l w i t h o u t m u s c l e s , 11.57 AE 4.57 MPa in the model with 50% muscle volume, and 11.13 AE 4.51 MPa in the model with 80% muscle volume, and 10.92 AE 4.33 MPa in the model with 100% muscle volume. The mean pressure on the vertebral body in the model without paraspinal muscle, and with 50%, 80%, and 100% paraspinal muscle volume were 14.02 AE 2.82, 13.82 AE 2.62, 13.65 AE 2.61, and 13.59 AE 2.51 MPa, respectively. Conclusion.Using FEM, we observed that the paraspinal muscle volume decreases pressure exerted on the lumbar vertebral column. Based on these results, we believe that exercising to increase paraspinal muscle volume would be helpful for spinal pain management and preventing lumbar spine degeneration.

With the rise of electric vehicles, the use of battery modules, which are key units that drive vehicles, is increasing. The battery housing is the final form of a battery system mounted on electric vehicles, and is generally made of aluminum alloys, located at the bottom of the vehicle. The aluminum housing has a special shape to accommodate the battery module and is produced by welding extruded panels. This study applied friction stir welding (FSW) to weld 2.5 mm thin aluminum plates in order to improve the weldability and productivity. To increase productivity, we compared the mechanical properties after performing experiments under various FSW conditions. As a result, it was possible to derive speed-enabling welding conditions that can improve productivity without decreasing tensile strength. Deformation occurred in the structure during welding, causing gaps in the structure. Since these gaps have a significant influence on the degradation of mechanical properties after welding, the welding deformation at each step of welding must be calculated and reflected in the process. This study used the inherent strain method to calculate the deformation of each step of welding to apply automatic welding, and reduced the analysis time to 1/30 compared to the thermal elasto-plastic analysis method. Finally, this study verified the validity of the analysis method by comparing the experimental results with the numerical results using the inherent strain method. validation, S.K. and K.L.; formal analysis, S.K.; investigation, S.K. and Y.J.; resources, S.K. and K.L.; data curation, S.K. and K.L.; writing-original draft preparation, S.K.; writing-reviewing and editing, Y.J. and K.L.; visualization, S.K.; supervision, K.L.; project administration, K.L.; funding acquisition, K.L.

Generally, equipment or mechanical parts are worn out by abrasion, impact, erosion, and environmental corrosion. To reduce these losses, the welding that wears the surface of the material with abrasion or corrosion resistance is called overlay welding. Corrosion and high temperature oxidation are very important factors in overlay welding material selection because they have a great effect on wear rate. Typical equipment is made of carbon steel, stainless steel or a material that is not wear resistant. Therefore, overlay welding is applied to parts where the parts themselves are subject to severe wear or corrosion. The diffusion of chlorine and alkaline ash during the combustion process causes foiling, corrosion, and erosion in the water wall panel & tube which is a heat transfer device. In order to protect the water wall panel & tube from various chemical and physical phenomena occurring during the combustion process, heat-resistant alloy steel such as Inconel is overlay welded on the outer surface of carbon steel pipe. However, since the length of the water wall panel & tube is more than 7 meters, the deformation after overlay welding is very large and the straightening work requires a lot of time and money. Also, since cooling water flows through the pipe during welding, the temperature of the cooling water also affects the welding deformation. In this study, welding process sequence and coolant temperature are optimized to minimize welding deformation during overlay welding.

PURPOSES :This study is to investigate the mechanical performance of the fiber reinforced lean concrete with respect to different types of fibers. METHODS :Increased vehicle weight and other causes from the exposed conditions have accelerated the deteriorations of road pavement. A new multi-functional composite pavement system is being developed recently in order to extend service life and upgrade the pavement. A variety of tests were conducted before and after hardening of the concrete. RESULTS :From the test results, it was found that the use of different types of fibers did not affect the compressive strength development. This might be due to the inherent property of the lean concrete. When steel fibers were used relatively greater flexural strength and flexural fracture toughness were developed. Also addition of fly ash by replacing a part of Portland cement the fracture toughness was slightly increased. CONCLUSIONS :It has been known that the addition of fibers and use of mineral admixture can be positively considered in the development of multi-functional composite pavement system as its required mechanical performance is obtained. Keywords fiber reinforced lean concrete, base course material, mechanical properties, fly ash

52,000 deadweight ton class icebreaking tanker is designed to comply with Russia Maritime Register of Shipping(RMRS) ice category Arc7 and IACS CSR-H. The ice breaking load was obtained from the DDePS of the ABS Classification Society and the limit load calculation was examined through the Abaqus nonlinear analysis. The collision location and iceberg type selection were adopted to define iceberg-hull collision scenarios. Nonlinear analysis simulated ice breaking process by using LS-DYNA.