• Journal of the Korean Society of Industry Convergence
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• v.25 no.3
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• pp.357-363
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• 2022

In this study, in order to develop an non-slip metal grating, the stability of the grating according to the span of the grating and the gap and height of the bearing bar was evaluated. The optimal shape design of the grating was performed using the results of determining the stability of the grating. The purpose of this study is to determine the stability according to the spacing and height of the bearing bar by applying the design pressure at the design stage to develop the anti-skid grating, and to design the optimal shape for cost reduction. In the optimal design, the target variable was set as the mass, and the optimal design of the grating was performed based on about 20%. Regardless of the height of the bearing bar of the grating, the stress and deformation of the span and the grating showed a proportional tendency to each other, and it was found that the stress decreased as the height of the bearing bar increased. Based on the structural analysis results, an optimal design was performed using mass as the objective variable, and the existing 2mm thickness was changed to 1.6mm, reducing the mass by about 19%. The stress increased by about 4.4% compared to the maximum stress of the existing grating, but the minimum safety factor was 3.1, indicating that the optimally designed grating was stable.

• Journal of the Korea Safety Management & Science
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• v.24 no.2
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• pp.127-134
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• 2022

Production management in the automobile parts industry is carried out according to the production plan of the customer, so it is important to prevent shortages in product supply. As the product composition became increasingly complex, the MES System was built for the purpose of efficient production plan management and inventory management, but its utilization is low. This study analyzed the problems of the MES system and sought to improve it. Through previous studies, it was confirmed that the inventory management of the pull approach that actually occurred in the warehouse is more suitable than the push approach based on the forecast of the warehouse for the volatility, complexity, and uncertainty of orders in the auto parts industry. To realize this, we tried distributed MRP by using the ADO function of VBA to link the standard information of the MES system with Excel and change the structure of the BOM table. Through this, it can help increase the accuracy of production planning and realize efficient inventory management, thereby increasing the utilization of the MES system in the auto parts industry and enhancing the competitiveness of the company.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.5
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• pp.827-833
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• 2022

In this study, the prediction of the bending angle for the 350 A bellows-type expansion joints and the structural stability according to the load were determined. The stability of the 2km piping system was predicted by applying the allowable bending angle of the expansion pipe joint obtained from the analysis. The maximum bending angle was calculated through bending analysis of the bellows-type expansion joints, and the maximum bending angle by numerical calculation was about 1.8°, and the maximum bending angle of the bellows obtained by comparing the allowable strength of the material was about 0. 22°. This angle was very stable compared to the allowable bending angle (3°) of the expansion pipe joint regulation. By applying the maximum bending angle, the allowable maximum deflection of the 2 km pipe was about 3.8 m. When the seismic load was considered using regression analysis, the maximum deflection of the 2km pipe was about 142.3mm, and it was confirmed that the bellows-type expansion joints and the deflection were stable compared to the allowable maximum deflection of the pipe system. These research results are expected to present design and analysis guidelines for the construction of piping and the development of bellows systems, and to be used as basic data for systematic research.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.3
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• pp.283-288
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• 2021

A tungsten material using a pressure sintering process and a titanium sintering additive was prepared to evaluate the microstructure, and mechanical properties of flexural strength and hardness. In addition, the reliability on each hardness data was evaluated by analyzing the distribution of the hardness of the tungsten material using the Weibull probability distribution. In particular, the optimal manufacturing conditions were analyzed by analyzing the correlation between the sintering temperature and the mechanical properties of the tungsten sintered body. Although the sintering density of the tungsten material was hardly changed up to 1700 ℃, but it was increased at 1800 ℃. The hardness of the tungsten sintered material increased as the sintering temperature increased, and in particular, the tungsten material sintered at 1800 ℃ showed a high hardness value of about 1790 Hv. It showed relatively excellent flexural strength at a sintering temperature of 1800 ℃.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.3
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• pp.315-321
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• 2021

In this study, the natural frequency analysis of the fuel pipe and vibration test jig was performed as a basic study to determine the vibration characteristics of the vehicle's fuel pipe and the stability analysis of fatigue failure of the pipe. The natural frequencies of the fuel pipe and the fuel pipe with the test jig were calculated and the results were compared. As a result of the analysis, it was found that the natural frequency of the fuel pipe and the natural frequency of the test jig differed about 7 times, so that the vibration of the test jig did not affect the vibration of the fuel pipe. In addition, as a result of the natural frequency analysis of the fuel pipe itself and the pipe with the test jig attached, the maximum error is less than about 1%. In the future, it was suggested that the analysis of the design changed fuel pipe may be performed without a test jig.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_2
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• pp.961-968
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• 2022

Hydrogen embrittlement leads to the damages in bolts, nut, especially, high pressure valves, in the semiconductor facilities, hydrogen vehicles, hydrogen stations and so on. Monel material has higher strength than SUS material. Therefore, even though Monel material with special alloy is usually used to prevent the hydrogen embrittlement, it needs powerful drawing system to manufacture the rectangular or hexagonal bar using circular bar. The purpose of this study is to investigate the characteristics of plastic deformation of Monel material and 2 rollers of rolling unit in plastic limit through numerical analysis. As the results, it was predicted that, based on mean stress, as the rolling step was increased, the rolling force of rolling unit was decreased. In addition, the heat treatment for Monel material was needed because of residual stress due to plastic deformation. As for rollers, the roller was safe about 1.86 times compared with that of ultimate strength. In this study, as the roller 2 showed larger stress than roller 1, thus, roller 2 should be designed carefully to guarantee the safety. Further it was confirmed that the reaction force of roller could be helpful in bearing design.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_2
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• pp.987-992
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• 2022

STS 410, a representative martensitic stainless steel, contains 13 % chromium and is used for building materials, automobile parts, office equipment, kitchen utensils, and tableware. In general, the strength of STS 410 changes by the carbon content, and STS 410 of low carbon has excellent toughness and high carbon has excellent abrasion resistance. In this study, a fatigue test was performed on the STS 410 material to evaluate the exact fatigue limit and to evaluate the behavior of the material against fatigue. In addition, the effect on burnishing, a kind of plastic processing that creates a smooth surface by pressing a ball or roller on the inner and outer surfaces of the material was evaluated. The fatigue limit was 509 MPa for the STS 410 material, and the result was 54.5 % of the tensile strength. The fatigue limit was 542 MPa for the specimen of diamind burnished STS 410 material, and it was 58.5 % of the tensile strength.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.541-547
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• 2022

Before making a prototype, we predicted the inlet/outlet differential pressure and flow coefficient, which are the most basic design data for the valve through the design and numerical analysis of the trim, which is the most important in the localization development of the 1500Ib high differential pressure control valve used for boiler feed water. As a result, the design value and the analysis value were found to be about 98% similar. The flow field within the fluid velocity of 23m/s to prevent cavitation was also found. The result of the numerical analysis on thermal stress due to the characteristics of valves exposed to high temperatures showed that it was found to be about 18% less than the allowable stress of the bolt fixing the trim. When all loads such as pressure, self-weight, and vibration are applied, however, it is judged to go beyond the currently calculated thermal stress, exceeding the allowable stress.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.621-626
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• 2022

Tungsten is a high melting point metal unlike other steel materials, and it is difficult to manufacture because of its high melting temperature. In this study, pressure sintering process method was applied to manufacture the tungsten materials at low temperature. Therefore, it is necessary to densify the sintered material by using a sintering additive. Studies have been conducted on how the amount of titanium for sintering tungsten affects the mechanical properties of tungsten in this study. In order to secure the densification mechanism of tungsten powder during the sintering process, the characteristics of the sintered tungsten material according to the change of titanium content were evaluated. It was investigated the relationship between sintering parameters and mechanical properties for densification of microstructures. The sintered tungsten materials according to sintering additive content showed high sintered density (about 16.31g/cm³) and flexural strength (about 584 MPa) when the content of sintering additive was 3 wt%. However, as the content of the sintering additive increases, mechanical property of flexural strength is decreased, and the porosity is increased due to the heterogeneous sintering around titanium.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.1
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• pp.201-209
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• 2023

Recently, fiber-reinforced composites have been widely used in various industrials fields. In this study, the mechanical behavior, especially fracture behavior, of biomimetic fiber-reinforced composites subjected to pressure loading was analyzed using finite element analysis (FEA). The fiber alignments in the biomimetic composites formed a helicoidal structure, wherein a stacking sequence involved a gradual rotation of each ply in the multi-layered laminated composites. For comparison, cross-ply composite samples with fibers arranged at 0° and 90° were prepared and analyzed. In addition, the mechanical behavior was analyzed based on combinations of the stacking sequence of carbon-fiber composites and glass-fiber composites. The FEA results showed that, when compared with the cross-ply samples, the mechanical properties of the biomimetic composites were considerably improved under pressure loading, which was applied to one side of the composites. Thus, the biomimetic helicoidal structure significantly improved the mechanical properties of the composites. Placing materials having high elasticity and strength in the outermost layers (the layer of the side on which pressure was applied and the opposite side layer) of the composites also significantly contributed to improving the mechanical properties of the composites.