This paper deals with the current technology status and technology development direction on shape shifting drone. A shape shifting drone is defined as a drone for which its shape and/or function of its platform in flight can be changed by shape shifting technology in order to fulfill a variety of missions effectively in harsh mission environment. A shape shifting drone can be classified as a rotary-wing based, a fixed-wing based, or a biomimetic based shape shifting drone. This work describes technology trends of domestic and foreign countries. It identifies core technologies and development direction. This work will be useful for planning research and development programs on required technology for the development of shape shifting drone in the future.

This study proposed a conditional generative adversarial network (cGAN) model for predicting steel plate deformation based on heating line positions in a line heating process. A database was constructed by performing finite element analysis (FEA) to establish relationships between heating line positions and deformation shapes. Deformation shapes were converted into color map images. Heating line positions were used as conditional labels for training and validating the proposed model.
During the training process, generator and discriminator loss values, along with MSE and R² metrics, converged stably, demonstrating that generated images closely resembled the actual data. Validation results showed that predicted deformation magnitudes had an average relative error of approximately 3% and a maximum error of less than 7%. These findings confirm that the proposed model can effectively predict steel plate deformation shapes based on heating line positions in the line heating process, making it a reliable predictive tool for this application.

Microfluidic chips have become a critical component in advanced applications such as biochemical analysis, medical diagnostics, drug development, and environmental monitoring because of their ability to precisely control fluid flow at the microscale. The functionality of these chips is highly dependent on the precision and dimensional stability of microchannel structures formed on them. While injection molding is an efficient method for a mass production of microfluidic chips, it is required to minimize undesirable deformation due to thermal and mechanical stresses, which can degrade the overall performance. This study investigated global (Macro-scale) and local (Micro-scale) deformation behaviors of injection-molded microfluidic chips. Effects of processing parameters, including mold temperature, melt temperature, filling time, and packing pressure, were investigated. The Taguchi-based design of experiments approach was employed to systematically analyze these effects and to determine optimal conditions to minimize deformation.

The Forming Limit Diagram (FLD) is a criterion used to assess the formability of sheet metal during a manufacturing process. Traditionally, FLDs are obtained through manual measurements using Mylar tape or through the use of automatic deformation measurement systems such as ARMIS and ARGUS. However, the use of Mylar tape is not user-friendly and can result in errors. Additionally, the cost of using automatic measuring equipment is high. To address these challenges, we propose a method that utilizes a low-cost USB digital microscope and the Python-based open-source library, OpenCV, to obtain forming limit diagrams. This approach allows for the measurement of deformation on specimens by analyzing circles printed on them. To evaluate the performance of this method, a circular grid was printed on a sus430 0.3 t specimen and a nakajima test was conducted. The strain data obtained using this system was then compared to the FLD obtained with the ARGUS system. The results confirmed that the formability of sheet metal can be assessed at a lower cost using our proposed method.

In Hopkinson bar theory, stress, strain, and strain rate can be determined by analyzing the dimensions of the specimen. When conducting Split-Hopkinson Pressure Bar (SHPB) experiments, the stress-strain curve is obtained by considering the entire length and width of the specimen. However, in Split-Hopkinson Tensile Bar (SHTB) experiments, it is important to only consider the regions where deformation occurs in order to accurately determine the dynamic material properties. This study introduces a method for selecting the dimensions of the deformed region (LD and WD) in plate specimens for SHTB experiments using Finite Element Analysis (FEA). The analysis involved varying the length and width of a 1 mm thick SUS430 specimen, and the deformed region was determined using the proposed method. The stress-strain curves obtained from this region were then compared with the input Cowper-Symonds model. The validity of the proposed approach was confirmed, as the percentage error between them ranged from 2.54 to 6.62%.

The use of reflective optical systems is essential to acquiring high-resolution image quality in aerospace applications that observe distant objects. The geometric shapes of large-aperture reflective optical systems can be deformed depending on various operating and space environments, which deformation consequently affects optical performance. In this study, we predict the image quality of a reflective aerospace optical system according to various environmental changes. In particular, the shape deformation due to vibration and heat generated from the launch vehicle was mainly observed, and the effect on gravity was also considered. The variations of image quality, such as Modulation Transfer Function (MTF) and wave-front error (WFE), were also observed by importing the deformed shapes into the optical simulation tool. This study is intended to provide approaches to reduce the cost and lead time to develop aerospace optical systems.

Recently, the demand for electric vehicles is intensively increasing in accordance with environmental issues in automotive industries. Given that noise level from the electric vehicles is significantly lower than that from conventional vehicles with internal combustion engine, noise management has become more critical. Conventionally, glass run channel (GRC) is used to block the noise and contaminants from outside of vehicle. In this work, the friction and degradation characteristics of GRC with thermoplastic vulcanizate substrate were assessed. The tests were performed using the reciprocating tribo-tester developed to replicate the contact sliding between GRC and window glass. Also, the test conditions were determined in consideration of operating condition of GRC. As a result, the plastic deformation of the lips due to creep and wear of the slip coating deposited on the lip surface were found to be major degradation mechanisms. Furthermore, it was shown that the friction and degradation increased significantly due to the misalignment between GRC and window glass, associated with the significant increase in the reaction force. The results of this work provide fundamental understanding of the degradation characteristics of GRC, and therefore are expected to be useful for the design of GRC with improved performance.

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.

Stretchability enables the device to be patched to a curved surface or to be folded several times to maximize usability. Among many methods, the pre-strain method is advantageous in that the stretchability as much as the pre-strain applied to the substrate is guaranteed even without material improvement. When the pre-strain is restored to its original state, the thin film gets wrinkled or the substrate gets buckled. Wrinkles and buckling that appear in this way are affected by the physical properties and dimensions of the substrate, and it is necessary to analyze their effect. In this study, a theoretical approach was used and a nonlinear post-buckling analysis was performed using a finite element method. The analysis was divided into two steps: the pre-strain step and the recovery step. According to the analysis results, it was possible to predict and analyze the wrinkle and buckling behavior due to pre-strain according to the physical properties and dimensions of the substrate. The pre-strain analysis method can be applied to multi-layer structures with three or more layers and can be used as a method to analyze wrinkle suppression and wrinkle shape control in future studies.

In this study, acoustic emission (AE) signals associated with the behavior of materials in the magnesium alloy (Mg AZ31B) tensile test were analyzed. The AE sensor was attached with the material to measure the AE signals. During the tensile experiment, the AE sensor measured the elastic waves generated inside the specimen. The AE parameters, such as, the signal energy, duration, and frequency centroid, were studied. We also analyzed the effect of the materials size and tensile speed on the AE signals. As a result, the lowest frequency centroid value occurred at the yield and fracture points. As the width and length of the specimen increased, the number of hit counts increased and the peak frequency occurred. Other AE parameters, such as, the duration and frequency centroid, were not affected. As the tensile speed increased, the hit decreased and the frequency centroid decreased in the elastic region. It was found that in the detection of the yield and fracture deformation, the number of counts, and frequency centroid were appropriate.

This paper investigated the hot deformation behavior of an AISI 4340 material through high-temperature compression experiments. The compression tests were performed to obtain stress-strain curves at processing temperatures of 900, 1,000, 1,100, and 1,200℃, and the strain rates of 0.01, 0.1, 1, and 10 s^-1 up to a true strain of 1.0 in the high-temperature compression mode of Gleeble^® 3,500. A novel 3D processing map, constructed through power dissipation efficiency and Ziegler"s instability criterion, is proposed. The deformation behavior was analyzed by observing changes in the microstructure from the high-temperature compression tests. Electron back scatters diffraction (EBSD) was used to characterize the microstructures for various processing parameters. The process workability of finite element analysis (FEA) was examined in the deformation flow instability map in the three-dimensional space for each strain. As a result, each particle"s strain rate and temperature of FEA data can be observed in a three-dimensional flow instability map to control the temperature and process speed to avoid unstable zones.

The bone scaffold is artificial mechanical support, that is implanted on collapsed bone microstructure. The clinical field has become interested in that, because it is free of immunological rejection. However, few studies have analyzed quantitively the mechanical interaction with the surrounding bone tissue, when the bone scaffold is implanted. Thus, the purpose of this study was to analyze structural behavior variance, according to porous structures of the bone scaffold. This study set the proximal femoral head as the implantation skeletal system, and defined bone scaffolds (i.e. triangular, rectangle, circular, honeycomb) with four porous structures. Then, structural behavior variance was analyzed, caused by the implantation of bone scaffolds. As a result, it was quantitatively confirmed that a porous structure such as a normal bone that can transmit and support an external load is important.

The fundamental flow models of metallic materials at room temperature, including the Ludwik, Hollomon, Swift and Voce models, were evaluated in terms of tensile test with an emphasis on the necking phenomena and post-necking behavior, to emphasize their limitation in satisfying tensile strength and Considère condition as well as the pre-necking and post-necking strain hardening. To resolve this limitation and enhance the applicability of the new proposed flow model to typical strain hardening materials, the Ludwik-Swift blended flow model is proposed after investigation into three blended flow models among the Ludwik, Voce and Swift models. Results revealed that there is no interpolation-based blended flow model of the fundamental flow models for the example flow curve exhibiting typical strain hardening but that the extrapolation-based combination of them can provide an engineering solution when the Ludwik and Swift models are blended. It was revealed that the reason for their good matching lies in the distinct difference in the strain hardening exponent, between the Ludwik and Swift models in the case of metallic materials with typical strain hardening.

Chemical Mechanical Planarization (CMP) is an essential process for device integration and planarization in a semiconductor manufacturing process. The most critical function in the CMP process, is to predict and cover the geometrical characteristics of various sizes and densities, of patterned wafers for local and global planarization. To achieve the wafer-level and die-level planarization, it is necessary to understand the contact mechanism between the CMP pads and the macro-scale patterns. In the macro-scale pattern, pad deformation is divided into two layers: an asperity layer and a bulk pad layer. Through bulk pad deformation, asperity contact distribution within the pattern is predicted. In this paper, the distribution of asperity contact according to the pattern geometrical characteristics was analyzed, through large-area real contact area (RCA) measurement. Bulk pad deformation was predicted by analyzing RCA distribution according to pattern geometry such as pattern size and density, pattern shape and step height according to the polishing time, and applied pressure. Additionally, through the distribution of the contact area and the number of contact points, the rounding phenomenon and planarization characteristics in the pattern CMP were predicted.