Bone plates are a medical device used for fixing broken bones, which should not have a crack and hole defect. Defect detection is very important because bone plate defect is very dangerous. In this study, we proposed a defect detection model based on a parallel type convolution neural network for detecting bone plate crack and pore deformation. All size filters were different according to the defect shape. A convolution neural network detected pore defects. Another convolution neural network detected the crack. Two convolution neural networks simultaneously detected different defect types. The performance of the defect detection model was measured and used for the F1- score. We confirmed that performance of the defect detection model was 98.4%. We confirmed that the defect detection time was 0.21 seconds.

This study deals with the structural integrity of a co-axial octocopter cargo drone. Most unstable states in progress of various flight missions of the cargo drone are considered to be derived from take-off and landing operations. In order to evaluate the structural integrity of these states, three-dimensional FE (finite element) simulation using whole frame assembled with structural members and components is performed, and then the effective stress level and deflection degree are investigated. Also, topology optimization is adopted to improve the locally concentrated stress and large deflection around front and rear sections of the motor-support side member. From topology optimization, it is ensured that the shape and location of plate support have to be modified for improving the stress level and the deflection degree. Based on the optimized and modified feature, FE simulation is re-performed. Consequently, it is confirmed that the effective stress and the deflection are reduced to about 26.67% and 19.15% around the side member, respectively.

This study reports an autonomous fine dust source tracking system of a water spray robot for high-rise building demolition. The core function of this system is performing a self-controlled fine dust tracking of the endpoint of the excavator, which is the fine dust generation point. The water spray robot has a lift with a parallelogram-shaped linkage to lift the water spray drum to 10 m from the ground. The sensor network system is connected to the robot and the excavator to calculate the relative position of the water spray drum and excavator endpoint using forward kinematics. RTK-GPS is attached to the robot and the excavator to calculate the relative distance. By sensor network, forward kinematics, and RTK-GPS, the water spray robot can autonomously track fine dust generation point and spray water to the endpoint of the excavator. The experiment was conducted to confirm the accuracy of kinematics calculation and tracking performance of the robot. The first experiment showed that the calculation result of forward kinematics was accurate enough to fulfill tracking operations. The second experiment showed that the tracking accuracy was precise enough, meaning that the robot could autonomously track fine dust generation point.

The literature states that the existing guidelines mainly focus on the ultimate strength of uniform corroded joints in the Jacket-type re-assessment. However, joints are non-uniformly corroded in different shapes in reality. Results derived from theoretical equations in these scenarios are significantly different from the actual capacity of the frame joints. This paper studies the influences of thickness and corroded area on the T- joint’s ultimate strength for a chord based on the numerical model ABAQUS. Numerical results show the effects of location and dimension at corroded areas on the tubular joint ultimate strength. Moreover, this research proposes a new formula based on API to estimate the strength of T-joints connected with non-uniform corroded compressive braces in certain conditions. This equation is validated by comparison of the numerical simulation in independent cases.

With advancements in the 3D printing technology, many industrial sectors are transitioning from traditional production methods, such as cutting processing, and casting, to utilizing 3D printers for manufacturing. For instance, in the automotive industry, the production of vehicle upright knuckle parts typically involves casting followed by machining processes, such as turning and milling, to achieve dimensional accuracy. However, this approach is associated with high processing costs and longer lead times. This study focuses on the production of vehicle upright knuckle parts using a selective laser melting (SLM)-type 3D printer, with SUS 630 as the material. To evaluate the feasibility of utilizing this method in industrial vehicles, this study conducts static and modal analyses, along with topology optimization. Additionally, experimental test drives are performed with the parts installed in KSAE BAJA vehicles, and modal frequency experiments are conducted. The objective of these analyses and experiments is to assess the performance, reliability, and applicability of utilizing SLM-based 3D printing for manufacturing vehicle upright knuckle parts by optimizing the design through topology optimization and evaluating the results through experiments and analysis.

This paper describes the control method of an electric gripper using a current control system. A current control system was designed and fabricated, and it consisted of a current sensor, an amplifier, and a precision voltage regulator. As a result of calibration by applying the current control system to the electric gripper, the error was less than ±0.34%. The proportional gain for the PI control of the gripper was 0.41, and the integral gain was 0.01. As a result of the control characteristics test, the arrival time was 0.79 s and the steady-state error was ±5 mV (±0.025 N). As a result of the experiment of holding the object, the gripper was able to hold the object safely. Therefore, the electric gripper applied using the current control system performed excellently in current control based on the reference force (grabbing force); thus, it is judged that it can be used to safely grip various objects in various fields.

Condensation is an important research topic that ensures increased energy efficiency. Our researchers aimed to optimize heat transfer in industrial heat exchanger tubes through surface modification. We first succeeded in fabricating superhydrophilic and superhydrophobic tubes using surface modification. We observed the condensation phenomenon on the outside of the tube and evaluated the heat transfer performance through a condensation experimental facility. As a result, we found that the condensation heat transfer efficiency of superhydrophobic tubes is superior to that of conventional tubes. However, the heat transfer efficiency of the superhydrophobic tube reduced with an increase in saturation. To improve performance degradation, superhydrophilic and superhydrophobic hybrid tubes were fabricated and evaluated for their potential to improve heat transfer efficiency. As a result, we found that the liquid film generated by filmwise condensation on the superhydrophilic surface swept past the residual droplets generated by dropwise condensation on the superhydrophobic surface, resulting in the best heat transfer performance. Our results break the stereotypes of previous studies and provide a new paradigm for achieving optimal heat transfer performance on large-area curved surfaces. This research is expected to be widely applied in a variety of industries where energy efficiency is critical.

Recently, as UAM has been in the spotlight worldwide, the issue of aerodynamic noise generated from propellers has emerged. Therefore, changes in thrust and aerodynamic noise were compared while changing the propeller lay-out distance. The designed propeller model was analyzed using ANSYS Fluent, a CFD software. Based on steady-state analysis, transient analysis was performed, and SPL was calculated using the FW-H noise model. Based on the standard propeller lay-out distance of 0.1 R (0.12 mm), 5 cases from 0.2 R to 0.6 R were compared with the reference model at equal intervals of 0.1 R. The thrust increased by up to 3.5% as the propeller distance increased. In most listeners positioned to measure SPL, noise was reduced by 0.07-0.7% in the improved model compared to the reference model due to reduction in local vorticity. However, because pressure fluctuation due to the increase in thrust and high SPL in the low-frequency region were measured, noise increased by 0.6% to 3.5% in some listeners. Increasing the propeller distance enhances thrust performance, but inevitably increases noise due to pressure fluctuations and SPL in the low-frequency region. Therefore, strict analysis of noise prediction according to a specific frequency and various design shapes are needed.

Lately, due to the concentration of population in metropolitan areas, traffic congestion in the hub city has occurred, and future mobility AAM development is undergoing active progress to solve this situation. Accordingly, reducing noise pollution, which is pointed out as one of the problems of AAM, is an essential technical issue for urban operation. In this study, a duct, which is a representative aerodynamic noise reduction method, was used, and numerical analysis was performed using ANSYS FLUENT, a CFD software, according to the shape of struts in the duct. The FW-H of the transient-state LES model was used, and the steady-state analysis value was used as the initial value to save analysis time. Case 1 without strut, Case 2 with strut of an airfoil section, and Case 3 with strut of a rectangle section were designed and compared at a rotational speed of 6,000 RPM. Compared to Case 1, Case 2 and Case 3 showed improved thrust by about 7% and 2%, respectively. Compared to Case 2, Case 3 showed reduced OASPL from a minimum of 0.0793 dB to a maximum of 1.0072 dB. It was found that shapes of strut in the duct significantly affect thrust and aerodynamic noise.

In-Mold Electronics (IME) is a manufacturing method that integrates printed decorations and electronic circuitry with thermoforming and injection molding processes. The method enables the production of ergonomic, lightweight and durable parts through cost-effective processes that require less assembly. Herein, the effect of circuit shape on line-width change by thermoforming was investigated through experiments and analysis based on the K-BKZ nonlinear viscoelastic model. Two circuit shapes, a horseshoe and a coil, were proposed and their line widths after thermoforming were measured and compared to that of a straight line shape. In the horseshoe-shaped circuit, the line width decreased as the radius increased due to the influence of vertical stretching caused by thermoforming. However, the effect of the angle on the line width was insignificant. In the coil-shaped circuit, the width of the line decreased as the pitch increased. However, as the amplitude increased, the line width also increased, but the effect was not significant. For the circuit shapes of the straight line, horseshoe and coil shapes, the rate of change in line width was 4.4, 0.4, and 0.2%, respectively. After conducting research, it was found that the coil-shaped circuit is more effective in minimizing line-width change caused by film thermoforming.