This study reviewed types and dynamic behavior characteristics of shock-absorbing materials used in spent nuclear fuel transport containers. Among various shock-absorbing materials, wood, honeycomb, and foam materials were the most commonly used. Redwood and balsa wood are sustainable materials with excellent energy absorption properties and natural decomposition, but vulnerable to temperature and humidity. Although honeycomb materials have better mechanical strength than other materials, they only support unidirectional loads. Urethane foam and Fenosol foam materials have lower mechanical strength and lower shock absorption than others, but have higher lightness and fire resistance. They also allow users to control density and produce them. Due to their isotropic characteristics and ease of increasing or decreasing strength by adjusting density, foam materials are better for design and manufacturability than others. Shock-absorbing materials show more complex behavior characteristics than general steel materials. For shock absorption, large deformations are considered up to sections that greatly exceed the elastic region, inevitably increasing the complexity of behavior simulation. During design, to accurately simulate large deformation behavior, it is important to select an appropriate analysis property card and determine major influencing factors. An analysis-based review was additionally conducted for property cards typically applied to foam materials.
Recently, with the expansion of application of polymer composite materials, high levels of deformation compensation actions have been developed. However, there is a problem of high-temperature viscoelasticity that occurs over time after completing the injection molding process. In this study, changes of mechanical properties of the Moldflow program for injection molding were analyzed to verify the viscoelasticity phenomenon through deformation analysis. In addition, deformation analysis of plastic injection molded products according to arrangement of three ribs was conducted and two products with different geometric shapes of the same function were compared. As a result, it was possible to reflect the viscoelastic effect by reducing the elastic modulus and shear modulus of the material. It was confirmed that the geometric shape with thick ribs formed in multiple longitudinal directions was mainly responsible. On the surface of the product where the rib arrangement was parallel and perpendicular to the flow direction, the orientation was orthogonal to the linear direction and the maximum residual stress was 81.17 MPa, which showed the largest value. It was judged that viscoelastic phenomena could be predicted and that an arrangement of parallel and perpendicular ribs that might intersect should be avoided.
Hydrogen production using water electrolysis is generally a well-known phenomenon. Hydrogen produced using the water electrolysis method is an environment-friendly energy source called ‘green hydrogen’ that does not emit any environmental pollutants when using renewable energy as an energy source. This study aims to improve the efficiency of hydrogen production by using the ion transportation effect induced by a rotating magnetic force. For this purpose, the experimental conditions for ion transport were determined through an experiment using a copper wire and the rotating magnetic force for water electrolysis was applied using an alkali aqueous solution. Based on the results, an increase in the number of bubbles generated by the rotating magnetic force increased was observed. It is assumed that the efficiency of hydrogen production using water electrolysis can be improved by the rotating magnetic force.
A measurement of a users’ motion is widely attracting attention for a realization of robotic assistance in daily activities. The soft, wearable sensing suit enables the monitoring of outdoor activities, with high wearability and insensitivity to inertial force. In this paper, we propose a novel sensing suit for measuring the multi degree of freedom (multi-DOF) motion of the wrist joints. We used a fabric-based capacitance-type stretch sensor for high adaptivity to a textile form of suits. The sensor was attached to the body link, instead of the wrist joint to reduce the interdependency among each joint axis and the effect of unwanted disturbance. We adopted the Deep Neural Network for calibration, and verified the higher estimation accuracy on the estimation of the multi-DOF wrist motions. The performance validation proceeded with comparing to the linear-based regression, and the root mean-squared error on the angle measurement was improved at slow motion and fast motion. A real-time measurement interface was developed and demonstrated with a frequency of 250 Hz.
In order to maintain parts critical to using 3D printing technology, it is necessary to provide the user with information about powders, equipment, processing conditions, and inspection methods, as well as 3D CAD models used as input files for 3D printing operations. In order to address this issue, this paper proposes a manufacturing condition retrieval system that provides the information necessary for the maintenance of parts important to using 3D printing technology. To accomplish this, we define a data structure that stores manufacturing condition information for 3D printers. Then, after analyzing the user"s requirements, we design the manufacturing condition retrieval system. Finally, we implement a prototype system, construct a database using sample manufacturing condition sheets, and perform data retrieval experiments.
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Design for additive manufacturing knowledgebase development and its application for material extrusion Samyeon Kim, Hwijae Park, Sang-in Park Journal of Mechanical Science and Technology.2023; 37(12): 6193. CrossRef
In recent years, many soft wearable robots have been developed to overcome the limitations of conventional rigid wearable robots. Among the types of soft robots, soft pneumatic actuators (SPA) have been developed because of compliant characteristics that can guarantee safe human-robot interaction to improve one of the rigid wearable robot limitations. Especially, among various SPAs, inflatable actuators have been developed because they can be easily manufactured with various types of structures. However, the theoretical modelings proposed in the inflatable actuators are specific to apply to other joints, because their purpose is performance analysis. In this paper, we improve the theoretical modeling for the design of wrinkled inflatable actuators. The actuator’s design parameters such as height and number of layers were determined by the proposed theoretical model to provide the target torque. The soft actuator was manufactured with determined design parameters and then measure the torque for the various angles and pressures. The theoretical torque values acquired through the proposed theoretical model have an error of < 8% from the experimental torque values and showed higher accuracy than the previously proposed model.
Due to the ever-advancing technology in various production industries, the materials of machined products have been diversified from simple steel materials to composite materials, powder metallurgy materials and silicon. Powder metallurgy materials have excellent mechanical/chemical properties, but have disadvantages such as; difficulty in processing using conventional processing methods, increased processing cost and generation of a large amount of dust. In addition, the need for the development of specialized machine tools increases due to the disadvantages such as the frequent occurrence of burrs in tapping and drilling. In order to solve the problem of machining of high hardness sintered products, a method of maximizing productivity and efficiency by processing the powder metallurgy material before it is completely sintered is being studied. In this study, structural analysis of a turret center for the verification of structural stability of a turret center for processing powder metallurgy materials was carried out. In addition, the shape was optimized to improve the structural stability and weight and presented an optimal model. The study aimed at developing more reliable turret center through the optimized model.
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Automatic Measurement of Nanoimage Based on Machine Vision and Powder Metallurgy Materials Zhenghong Jiang, Chunrong Zhou, Haichang Zhang Advances in Materials Science and Engineering.2022; 2022: 1. CrossRef
Shape Optimization for Lightweight of the Metal 3D Printing Based Hybrid Machining Center Won-Young Jeong, Ho-In Jeong, Choon-Man Lee Journal of the Korean Society of Manufacturing Process Engineers.2021; 20(2): 80. CrossRef
Shape Optimization for Lightweight of the Line Center for Processing Complex Shape Parts Do-Hyun Park, Ho-In Jeong, Sang-Won Kim, Choon-Man Lee Journal of the Korean Society of Manufacturing Process Engineers.2021; 20(8): 86. CrossRef
Structural Safety of the Incinerator Transfer Conveyor Roller Chain Using GBO Bo-Ram Lee, Gyeong-Seop Park, Ill-Soo Kim Journal of the Korean Society of Manufacturing Technology Engineers.2020; 29(1): 9. CrossRef
This paper is a study of the machining characteristics, cutting force and surface roughness of a turning center by laserassisted machining. The laser-assisted machining (LAM) is an effective method to improve the machinability of difficult-tocut materials. The LAM has recently been studied for various machining processes, but the research on the threedimensional and turning-center machining is still insufficient. In this study, a machining experiment of the turning-center process was performed by the laser-assisted machining with Inconel 718. Before the machining experiment, performed to thermal analysis was for a selected to effective depth of cut. The cutting force and surface roughness were compared and analyzed. The machining experiment confirmed that the machinability was improved in the LAM.
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An Analytical Study on the Thermal-Structure Stability Evaluation of Mill-Turn Spindle with Curvic Coupling Choon-Man Lee, Ho-In Jeong Journal of the Korean Society of Manufacturing Process Engineers.2020; 19(1): 100. CrossRef
Deaf people use their own national sign or finger languages for communication. They have a lot of inconvenience in both social and financial problems. In this study, a finger language recognition system using an ensemble machine learning algorithm with an armband sensor of 8 channel surface electromyography (sEMG) is introduced. The algorithm consisted of signal acquisition, digital filtering, feature vector extraction, and an ensemble classifier based on artificial neural network (EANN). It was evaluated with Korean finger language (14 consonants, 17 vowels and 7 numbers) in 20 normal subjects. EANN was categorized with the number of classifiers (1 to 10) and the size of training data (50 to 1500). Mean accuracies and standard deviations for each structure were then obtained. Results showed that, as the number of classifiers (1 to 8) and the size of training data (50 to 300) were increased, the average accuracy of the E-ANN classifier was increased while the standard deviation was decreased. Statistical analysis showed that the optimal E-ANN structure was composed with 8 classifiers and 300 training data. This study suggested that E-ANN was more accurate than the general ANN for sign/finger language recognition.
Recently, interbody fusion cage devices have been developed and used for lumbar reconstruction. Stand-alone cages reduce segmental mobility. In this study, we evaluated mechanical properties and biocompatibility of lumbar stand-alone cages. Evaluation of mechanical properties followed the ASTM F2077 standard that covers methods for static and fatigue testing. The sterility test was ensured by the ISO 11737-2. The extractable substances test was ensured by the Korea pharmacopoeia. Cytotoxicity of the specimen was assessed using MTT assay as recommended by the international standard guidelines, ISO 10993-Part 5 for in vitro testing.
Recently, traffic accidents and damage on the highway have increased because of overloaded vehicles. The existing overload-detecting system has a low accuracy rate. An overload-detecting system using a weigh-in-motion (WIM) system has been developed to solve this problem. The WIM system can be used to detect overloaded vehicles by measuring the weight of the vehicles. The WIM system is divided into high-speed and low-speed types. The inaccuracy rate in the lowspeed WIM system results mainly from the low response rate of the sensor when the velocity is moving at more than 20 ㎞/h. In this study, a low-speed overload-detecting pad with a hydraulic structure using a WIM system was developed to make the system more accurate. The structural and formal analysis was carried out by using a finite element method (FEM) in order to analyze the structural stability and the extrusion velocity of the system. In addition, a static load test was performed to confirm the linearity and accuracy of the pad.
Recently, a high-precision ball screw is an essential part of high-speed machines. However, producing high-precision ball screws has been costly and time-consuming. Nowadays, a whirling machine is used to produce high-precision ball screws efficiently. Rotating multi-tips are used to turn the ball screw in the whirling machine. In this study, a structural analysis was performed by a finite-element method to develop a whirling machine. An improved model of the whirling machine was proposed by the analysis. In addition, a thermal analysis was performed to confirm the thermal stability. The results of the analysis can be applied in order to further develop the whirling machine.
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Heat Generation Characteristics of Whirling Spindle for Ball Screw Machining Hong-Man Moon, Sang-Won Kim, Ho-In Jeong, Choon-Man Lee Journal of the Korean Society of Manufacturing Process Engineers.2020; 19(10): 44. CrossRef
Recently, the problem of the accumulation of fine sludge from the cutting oil generated during machining processes has become a major threat to the environment. The fine sludge has adverse affects on the human body and the environment, and significantly contributes to marine pollution. However, a microfiltration technique that can process the sludge still needs to be studied and developed on a global scale. Therefore, it is necessary to develop eco-friendly equipment such as an ECO vacuum filter system and eco-friendly technologies for processing cutting oil. In this study, a structural analysis was carried out using a finite element method (FEM). Improved models of the suction chamber for the ECO vacuum filter system were proposed based on the analysis of the displacement and stress of the system. The model with the best result was then optimized using the commercial software, ANSYS. It was confirmed that, in the optimized model, displacement and stress were reduced in comparison with the initial model. Finally, the structural stability of the optimized model was verified through analysis.
Various species of insects display vivid colors, widely known as ‘structural color’ due to their optical interference. Morpho butterflies are famous for their brilliant iridescent colors, which arise from the photonic-nanostructures of optical interference on their wings. In this paper, we outline the results of a comparative study of the optical properties of bio-inspired Morpho butterfly structures with the widely known Distributed Bragg Reflector (DBR), conducted using a rigorous coupled-wave analysis (RCWA) method for the two structures. Almost analogous tendencies were observed for both Morpho and DBR structures. With variation in the surrounding media, however, Morpho structures showed an obvious peak shift while no significant changes were observed in DBR, which can be applicable.
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