Glass Molding Process (GMP) is an effective method for producing precise optical elements such as lenses. This simulation study aimed to predict the distribution of temperature and stress within a lens during a multi-stage cooling process of GMP. To develop an accurate simulation model including molds and lens, thermal contact conductance and boundary conditions were determined by analyzing experimental and simulation results. The developed model was used to investigate changes in temperature and maximum principal stress within the lens, considering variations in cooling time, speed, and method at each cooling stage. Simulation results indicated that trends of maximum temperature difference and maximum principal stress within the lens were consistent over time. Results also showed that the maximum principal stress inside the lens increased significantly with additional cooling after uneven temperature distribution caused by a relatively short cooling time. Compared to simulation results of the cooling process involving contact only with bottom surface of the mold, contact cooling with both top and bottom surfaces showed decreased residual stress at the end of cooling and maximum temperature difference within the lens. However, the maximum principal stress could be higher during the cooling process involving both surfaces.
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Optimization of heating and molding temperatures in multi‐station glass molding for a meniscus aspheric lens Jian Zhou, Baocheng Huang, Shihu Xiao, Lihua Li International Journal of Applied Glass Science.2026;[Epub] CrossRef
Total hip replacement is a representative treatment for avascular necrosis of the femoral head. However, the stress shielding caused by the replacement induces dissociation of the artificial hip joint and various complications. Many studies have tried to explore the stress shielding but, most studies have been conducted at macro level and not at micro level. Thus, this study aimed to quantitatively analyze the structural behavior of the proximal femur according to total hip replacement at the micro level to explore the stress shielding. For this purpose, this study selected the artificial hip joint of the single wedge type and implanted the joint into a proximal femur that has a high resolution of 50 μm. Then the structural behavior of the implanted femur was analyzed by comparing that of the intact femur under three daily activity loads. As a result, the high possibility was confirmed that the stress shielding will occur in both cortical and cancellous bones under the one-legged stance movements. Additionally, it was discovered that the cancellous bone had a considerably lesser chance of adducting at an angle similar to the neck shaft angle of an artificial hip joint.
The design of a substrate greatly affects the residual stress distribution and the deformation behavior of the repaired region by a directed energy deposition (DED) process. The objective of the present study was to investigate effects of edge length and slope of the substrate on residual stress and deformation characteristics in the vicinity of the repaired region for the repair of the straight damaged region using a DED process. Two-dimensional finite element analysis (FEA) was carried out using SYSWELD. Materials of the substrate and deposited powders were AISI 1045. The maximum residual stress during the deposition decreased when the edge length of the substrate increased, but increased when the slope of the substrate increased. The residual stress after a cooling state increased when the edge length and the slope increased. The displacement of the specimen increased when the slope of the substrate augmented. Finally, the methodology to select a proper edge length and slope of the substrate are discussed in this study.
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Artificial Intelligence Technologies and Applications in Additive Manufacturing Selim Ahamed Shah, In Hwan Lee, Hochan Kim International Journal of Precision Engineering and Manufacturing.2025; 26(9): 2463. CrossRef
Ground drilling technology for drilling has an environment where the major parts are prone to damage due to high stress, torque, and harsh operating conditions that can occur in the rotary power transfer structure. Research for preventing this damage is very important, as it can be coupled with the nature of drilling operations that take a long time in operation, which can lead to enormous cost and time consumption. Previous work investigated the cause of damage by analyzing the working environment and breakage of drilling holes for connecting rods, and a power transfer component of directional mud motors used in ground drilling systems. The material properties by heat treatment conditions for applied materials were analyzed. Based on prior work, we evaluated whether the stress concentration part shown in the analysis results matched the actual damage occurring point by conducting a structural analysis of the connecting rod, a damaged part, using the finite element analysis. We also analyzed how to reduce the stress concentration phenomenon that occurs during the mud motor operation by conducting part shape and design changes between the connecting rod and key parts.
In this study, the structural integrity of a 6.8 L composite pressure vessel manufactured using H2550 carbon fiber was evaluated by the finite element analysis method, and the reliability of the analysis method was verified by comparing the hydrostatic test and analysis results. The pressure vessel was manufactured using the filament winding method and a hydrostatic test was performed to evaluate the failure mode and burst pressure of the manufactured composite pressure vessel. To construct the finite element model, a cyclic symmetric model, which only considers 1° of the front part, was used to reduce the analysis time and increase the modeling efficiency. As the carbon fiber was wound along the curved surface of the dome part, the winding angle and lamination thickness were modeled to change according to the dome radius. Comparison of the analysis and test results confirmed similar behavior in the axial and hoop strain diagrams due to internal pressure. In addition, it was found that the maximum fiber direction stress of the hoop layer showed an error of 3%, verifying the reliability of the finite element analysis method.
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Techno-economic analysis of type III and IV composite hydrogen storage tanks for fuel cell vehicles Hyun Kyu Shin, Sung Kyu Ha Advanced Composite Materials.2024; 33(4): 527. CrossRef
In recent years, the machine industry has demanded high precision of the processed products and high efficiency of production due to the rapid development of technology. The grinding machine is being studied in many countries. The typical grinding machine is processed in the order of one side each. However, a 2-head simultaneous grinding machine processes both sides at the same time. Therefore, it has reduced processing time and improved precision. In this study, the overall structural analysis of a 2-head simultaneous grinding machine with high precision and high efficiency of productivity was performed. For high precision of the 2-head simultaneous grinding machine, the spindle taper angle was analyzed and optimized. When the spindle taper angle was 16 degrees, it had the highest chucking force. Therefore, the spindle had high precision as the spindle taper had the strongest force to chuck the collet. The analysis results can be applied to further develop the 2-head simultaneous grinding machine.
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Research on Stiffness Analysis and Technology of the Heavy Spidle Top Yongkang Wang, Bingwei Gao, Wenlong Han, Shilong Xue Current Materials Science.2024; 17(5): 540. CrossRef
This study aims to investigate the fatigue life of T-Type fillet welded joints for excavators subjected to bending loads, and also to verify the predicted fatigue life of the welded part using the effective notch stress method. Moreover, this study aims to determine an optimal toe angle of the T-Type fillet welded structure. In this context, the fatigue lives of T-Type fillet welded specimens (SM490A) were measured and the effective notch stress method for predicting the fatigue life of the T-Type fillet welded structure was verified by comparing with the FAT-225 curve of IIW (International Institute of Welding) as was suggested for the current types of welded structures. Considering simultaneously the scattering factor of the welded structure, the stress condition at the toe part higher than the root part, and the stress minimization condition of the toe part, the optimum toe angle at the T-Type fillet welding was identified at 30°. Likewise, the maximum stress (310.5 MPa) when the toe angle was 30° was about 14% less than the maximum stress (354.0 MPa) at 45°, and the fatigue life was improved by about 30%.
The photovoltaic power generation facility is usually installed outdoors and is extensively impacted by snow and wind power as well as external contact friction caused by snow and rain. In particular, since there is a markedly high possibility of damage from devastating wind power such as a typhoon, an overall safety evaluation is essential. However, most studies are conducted using cell-level stress analysis rather than cluster-wide stress analysis. Thus, in this study, a finite element analysis was performed on the entire support structure of the photovoltaic power generation facility, wherein the wind load was applied, and the portion wherein extensive stress was generated was identified. The results of the analysis showed that the stress in the rear side was relatively higher than in the front side of the support structure for the horizontal wind. Additionally, it was confirmed that a relatively high stress occurs in the lower side than the upper side of the support structure.
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The Study on the Vulnerable Part to Wind Load in Renewable Energy Photovoltaic Power Structures Kwang Pil Park International Journal of Highway Engineering.2023; 25(6): 27. CrossRef
Evaluation of Structural Integrity for Lifting-and-Lowering-Type Drone Station Using Fluid-Structure Interaction Analysis Sang Ho Kim, Jae Youl Lee, Sung-Ho Hong, Jehun Hahm, Kap-Ho Seo, Jin-Ho Suh, Young Sik Joung, Se Hoon Jeung Journal of the Korean Society for Precision Engineering.2021; 38(11): 841. CrossRef
Since earth pressure changes depend on soil depth and surrounding situations, the construction of earth retaining temporary structures should be able to measure the change of the earth pressure and cope with the changes. When the underground excavation and construction of earth retaining temporary structure repeatedly occur, the excavation should be less interfered by the earth retaining structure. A PS synchronize wale measures the horizontal deflection of the structure and generates tension on the wire rope by controlling the hydraulic cylinder so that the wale is in safe range. Since the horizontal load is canceled by pre-stress bending moment, the number of struts the horizontal load is reduced making the excavation interference is small. We evaluated the horizontal deflection of the PS synchronize wale with increasing tension and verified that the deflection of the PS synchronize wale can cancel out the horizontal load in the safety range of 5 mm. This occurs through a universal testing machine experiment simulating earth pressure. We are in the process of applying the PS synchronize wale to a test bed and expect it to be safer and more efficient than existing methods.
Elastomeric O-ring seals are widely used in static and dynamic applications due to their excellent sealing capacity, and availability in various costs and sizes. One of the critical applications of O-ring seals is solid rocket motor joint seal. In this, the operating hot gas must be sealed during the combustion time. In this study, we analyzed the behavior of O-ring compressed and highly pressurized by using the finite element method. The numerical analysis technique was verified through the comparison of analytical model and FE results. By using the verified FE method, the contact stress profiles at the sealing surfaces were investigated. It was found out that the contact stress profiles and deformation behaviors of the Oring are affected by friction coefficient, extrusion gap and stress relaxation considerably.
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Experimental and numerical evaluation of a rubber seal in a vacuum suction pad for an automatic mooring system Yeonhong Son, Taehyun Lee, Jung Yup Kim, Hwasup Jang, Jongjik Lee, Youngki Kim, Songkil Kim, Yongjin Kim Marine Structures.2024; 94: 103573. CrossRef
A Study on Sealing Performance Analysis for Electric Vehicle Coolant Control Hub Modules System Kim Gisu, Jeongsun Lee, Dongchul Kim, Myeongeui Song, Cho Wooyeon Transaction of the Korean Society of Automotive Engineers.2023; 31(3): 227. CrossRef
Structural Analysis and Experimental Study on the Spherical Seal of a Subsea Connector Based on a Non-Standard O-Ring Seal Dong Liu, Feihong Yun, Kefeng Jiao, Liquan Wang, Zheping Yan, Peng Jia, Xiangyu Wang, Weifeng Liu, Xiaoquan Hao, Xiujun Xu Journal of Marine Science and Engineering.2022; 10(3): 404. CrossRef
The blade cylinder root is a key component connecting the blade and pitch bearing of a wind turbine and is 20% of the blade’s manufacturing cost. Blade cylinder roots are manufactured using the open die forging method with steel alloy. However the blade cylinder root for 750 KW class wind turbine is manufactured using AA5083 cast material to reduce weight. The purpose of this study is to develop a hot open die forging method, through experiment and FEA, using AA5083 material manufactured by continuous casting. The forging process was designed using the mandrel forging method. Hot compression tests were conducted to obtain flow stress of cast microstructure at different temperatures and strain rates. Control parameters of each forging process were analyzed/compared to predict adaptability of the mandrel forging process. High productivity, good internal quality, shapes, and dimension were verified by prototypes manufactured by the proposed forging process.
A method for evaluating the safety of the corrosion fatigue of a high-pressure (HP) drum for the heat recovery steam generator (HRSG) is presented through a transient thermal stress analysis. To evaluate the corrosion fatigue, European Standard EN 13445-3 is applied to check whether the magnetite protective layer on the water-contacting surface can be preserved during the transient operating conditions: cold start, hot start, warm start, and load change. Static analysis is performed to analyze the stress due to the operating pressure, and transient thermal and structural analyses are performed for the transient operating conditions. As per EN 13445-3, the analyzed maximum and minimum stresses of the transient operating conditions at representative locations are compared with the allowable limits derived from the stress due to the operating pressure. In conclusion, the magnetite protective layer was preserved under the transient operating conditions and the HP drum was found to be safe for the corrosion fatigue. The method of analyzing the thermal stress and evaluating the safety of the corrosion fatigue presented in this research can be applied effectively in the design stage of various unfired pressure vessels exposed to high temperature and high pressure loading.
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Flow-accelerated corrosion in low-pressure evaporator of heat recovery steam generator: Experiments and fluid dynamics simulation Min Ji Song, Woo Cheol Kim, Dong-Jin Kim, Sung-Woo Kim, Soo Yeol Lee Case Studies in Thermal Engineering.2025; 72: 106263. CrossRef
Stress Analysis and Evaluation of Steam Separator of Heat Recovery Steam Generator (HRSG) Boo-Youn Lee Journal of the Korean Society of Manufacturing Process Engineers.2018; 17(4): 23. CrossRef
Fatigue Evaluation of Steam Separators of Heat Recovery Steam Generators According to the ASME Boiler and Pressure Vessel Code Boo-Youn Lee Journal of the Korean Society of Manufacturing Process Engineers.2018; 17(4): 150. CrossRef
Fluid Catalytic Cracking (FCC) Unit is a large-pressure vessel that converts heavy crude oil, which cannot be distilled, into light crude oil. With the growing interest in renewable energy sources due to environmental regulations, various studies investigating FCC Units are ongoing. The catalytic reactor in FCC Unit is a large structure that generates prolonged high pressure, leading to changes in the properties of the material during operation. Therefore, stress analysis must be conducted based on the application of the actual mechanical properties. In cylindrical thin structures such as the FCC reactor, a tensile test is difficult to perform, warranting the need for Shear Punch (SP) test that uses a small specimen. The properties were utilized in finite element analysis. To determine the boundary and load conditions needed for stress analysis, the operational conditions of the reactor and the conditions for internal pressure of ASME Code regulation were used to evaluate the stress.
In general, it is noted that the time domain technique becomes difficult to predict with the use of the accurate fatigue life, due to the lack of dynamic information of the structure. When the multi-axial stress is generated by the random vibration excitation in the mechanical structure, the fatigue analysis should have performed in the frequency domain as based on the multi-axial PSDs due to the problems presented above. Notably, Premont proposed a method to calculate the equivalent stress using PSDs in the frequency domain. In calculating the equivalent stress PSD, the phase difference between the multi-axial stress components was not considered at that time. This study propose a frequency domain fatigue analysis technique which can calculate the equivalent stress from the multi-axial PSD, as it works considering the phase difference that can appear in the real vibration excited structure. To verify this method, the conventional time-domain method as similar to a multi-axial rainflow method, is compared with the proposed frequency domain method in a simple simulation model. The multi-axial PSD and finally the von Mises stress model is reviewed, according to whether the phase difference between the multi-axial stress components is considered or not is analyzed.
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A method for editing multi-axis load spectrums based on S-transform dual-threshold theory Yongjie Lin, Zhishun Yang, Lingyun Yao Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering.2025;[Epub] CrossRef
Finite element analysis model was fabricated to confirm stress concentration phenomenon occurring in the wafer edge region in the CMP process, and it was confirmed if it corresponds to the measurement result of the actual pressure sensor. First, contact stress distribution at the edge of the wafer was calculated by the finite element analysis model in which material properties and boundary conditions were set up. As a result, an engineering contact stress distribution profile was obtained. Next, the pressure generated in the edge region of the wafer was measured using a pressure sensor that detects resistance change of the polymer. To compare with the result of the finite element analysis, the non-dimensional sensor signal unit was converted into the pressure unit, and correlation between the analysis and measurement results was obtained. As a result, the finite element analysis result, the actual pressure measurement, and the trend of the results were more than 90%. The results show that the finite element analysis model produced and modified in this study is consistent with the actual behavior trend of the components.
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FEM Studies of CMP Retainer Ring Using Metamodel Do Yeong Jung, Seung Heon Lee, Jun Geon Park, Jae Phil Boo, Jung Woo Lee, Byoung Wan Kim, Gu Young Cho Journal of the Korean Society for Precision Engineering.2025; 42(12): 1065. CrossRef
Variation of Pad Temperature Distribution by Slurry Supply Conditions Jinuk Choi, Seonho Jeong, Kyeongwoo Jeong, Haedo Jeong Journal of the Korean Society for Precision Engineering.2020; 37(12): 873. CrossRef
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