Earticle

This study applied ultrasonic cutting technology to solve the problem of lowering the cutting efficiency in the manufacturing process of transparent orthodontic braces, and in particular, used conical blades to improve cutting quality and efficiency. The existing process relied on manual work, resulting in problems such as quality deviation, labor strength, and shortening the tool life. Laser cutting technology was also attempted, but there was a limitation due to the generation of heat-affected parts and the generation of harmful by-products. Accordingly, in this study, a no-pressure cutting method using ultrasonic vibration (20~40 kHz) was introduced, and optimal process conditions were established based on the experimental planning method. Ultrasonic cutting using a conical blade minimized heat generation and improved the quality of the cutting surface, and secured stability in continuous processing. As a result of the experiment, the cutting efficiency and surface quality were superior to those of existing scissors cutting and CO₂ laser cutting, and the applicability of the automation process was confirmed. This study is a core technology that can realize the automation and high efficiency of manufacturing transparent correctors, and is expected to be expanded to the dental industry and precision processing industry in the future.

This study attempted to overcome the limitations of the existing manual process by applying automation technology to the polishing process of hand tools (scaling tools) for removing tartar. The current polishing process is causing quality deviation, high defect rate, and safety problems depending on the skill level of the worker. Therefore, this study attempted to achieve precise control of the polishing angle and reduction of the defect rate at the same time by applying machine vision-based high-precision location recognition and deep learning correction algorithm. In particular, the performance was verified through experiments by manufacturing tray design and prototype automation equipment that can stably supply various tools. As a result of the experiment, the proposed system reduced the polishing angle error from ±2.5° to ±0.5° compared to the existing manual work, and the defect rate was reduced from 5% to less than 2%. In addition, the work efficiency improved by more than 30%. These achievements provide an important basis for reducing dependence on foreign equipment in the domestic dental hygiene educational equipment market and securing competitiveness in overseas markets.

Overall system performance of hydrogen fuel cell system in a compact special vehicle is mostly influenced by thermal characteristics in chemical operation mechanism and heat dissipation with air flow. This study analyzes electrical output and air cooling characteristics of the fuel cell system with numerical methods. The heat generation rate were predicted with the output, and cooling characteristics around the radiator system were analyzed with air flow generated by the vehicle movement. The results showed that the fuel cell performance was largely connected with complicated air flow near the special vehicle.

The steel containment vessel of the NuScale small modular reactor (SMR) is designed to operate under submerged conditions, which influences its dynamic behavior during seismic events. Under such conditions, the interaction between the surrounding water and the containment structure plays an important role in the seismic response. In this study, seismic analyses of a submerged containment vessel are conducted using response spectrum analysis and time-history analysis. The results from the two methods are compared to examine the effects of fluid–structure interaction on the dynamic response. It is observed that the seismic responses under submerged conditions may exceed those under dry conditions due to hydrodynamic effects, including added mass and sloshing. These results indicate that fluid–structure interaction should be considered in the seismic analysis of submerged containment vessels.

When tube bundles submerged in water vibrate, their dynamic behavior is affected by the surrounding fluid. In particular, the added mass of the fluid leads to changes in the vibration characteristics of the structure. In nuclear power plants, steam generator heat transfer tubes are arranged in dense bundles and operate under submerged conditions, making fluid–structure interaction an important consideration. In this study, a fluid–structure interaction analysis is performed for a submerged group of tube bundles representative of nuclear power plant steam generator heat transfer tubes. Using a finite element–based coupled fluid– structural analysis, the vibration responses of the tube bundle are numerically investigated. The effects of the surrounding fluid on the vibration characteristics of the tube bundle are examined. The results indicate that the presence of the fluid significantly influences the vibration behavior of the tube bundle.

Hydraulic equipment, widely used in various industries such as construction machinery, agricultural machinery, and military vehicles, essentially requires hydraulic pipes for power transmission. Since the inflow of hydraulic fluid and pressure transmission are necessary to drive each attachment, hydraulic pumps are designed with multiple hydraulic lines. Conventional methods require the individual connection and disconnection of 4 to 6 hydraulic couplers when changing attachments, resulting in low work efficiency and potential safety hazards. Therefore, this study designed a device capable of simultaneously connecting a 6-way hydraulic line and verified its mechanism and stability. Specifically, a multi-coupler device capable of simultaneously connecting six hydraulic couplers was developed, and the structural stability of the fastening mechanism was analyzed. CATIA was utilized for 3D modeling, while ANSYS was employed to conduct structural analysis. The results of the analysis at each mechanism stage confirmed that sufficient structural stability was secured during the simultaneous coupling process of the 6-way hydraulic coupler

Planetary gear systems, which allow for the use of various gear ratios within a single gear system, are widely used in various industries. This study analyzes the loads of a planetary gear transmission system connected to the load-transporting motor of a crane used in various industries and proposes an optimal design method for the generated loads. This planetary gear system operates at 455 Nm and 3,000 RPM with a gear ratio of 1/3. Hydraulics are used for transmission, and the gear ratios are adjusted according to the crane's application, such as lifting and lowering loads. Basic 3D modeling was performed using the mechanical system design program CATIA. Romax, a gear system analysis program, was used to analyze the loads of the planetary gear system and propose an optimal design method based on theoretical data.

This study presents a parametric analysis to investigate the effects of gear design parameters on strength, efficiency, and noise characteristics for an electric drive system. The analysis was conducted under a single operating condition with an input speed of 2,000 rpm and a transmitted torque of 72 Nm, while the center distance was fixed. The module, number of teeth, pressure angle, face width, and helix angle were selected as key design variables. The results indicate that gear strength is mainly influenced by the face width and module, while gear noise, evaluated based on transmission error, shows high sensitivity to the pressure angle and helix angle. In addition, minimized peak-to-peak transmission error was observed when the mesh ratio approached integer values. These findings provide practical guidelines for low-noise gear design in electric drive systems.

This paper analyzes and enhances PPA6-IoV, a six-step privacy-preserving authentication protocol for the Internet of Vehicles. Formal modeling reveals vulnerabilities to replay, desynchronization, key-compromise impersonation, pseudonym–identity linkage, and weak forward secrecy from elliptic-curve secret reuse. We propose a strengthened variant that uses long-term secrets only as seeds for Diffie-Hellman exchanges, generates salted session-specific pseudonyms, and derives session keys via a context-bound key derivation function. A comparative evaluation of security and performance in large-scale IoV deployments is planned.

This paper identifies a critical flaw in a chaotic map–based multi-factor authentication protocol for UWSNs: its session keys depend on static long-term secrets, violating forward and backward secrecy if devices are compromised. We formally prove that an attacker can recover all past and future keys under such compromise. To fix this, we propose an enhanced key exchange using ephemeral chaotic-map–derived secrets, ensuring session keys remain secure even with long-term credential leakage. The improved protocol maintains comparable performance while achieving essential security properties.

This paper identifies a critical flaw in a chaotic map–based multi-factor authentication protocol for UWSNs: its session keys depend on static long-term secrets, violating forward and backward secrecy if devices are compromised. We formally prove that an attacker can recover all past and future keys under such compromise. To fix this, we propose an enhanced key exchange using ephemeral chaotic-map–derived secrets, ensuring session keys remain secure even with long-term credential leakage. The improved protocol maintains comparable performance while achieving essential security properties.

This study aims to evaluate the applicability of composite pouch films containing ionite as heat-suppressing pouch films for secondary batteries by manufacturing them and assessing their structural characteristics and temperature changes during charging and discharging. Film coating was performed using Coretech CT-AF300 to produce pouch films with varying ionite content and particle size. The influence of plasma treatment on the surface condition of PET film, aimed at improving coating adhesion, was also examined to derive optimal manufacturing conditions. Furthermore, the temperature characteristics of the pouch film during charging and discharging were investigated using an infrared thermal imaging camera and a self-developed test apparatus, respectively, to assess the feasibility of developing next-generation high-performance pouch films. Translated with DeepL.com (free version)

This study aims to evaluate the applicability of composite pouch films containing ionite as heat-suppressing pouch films for secondary batteries by manufacturing them and assessing their structural characteristics and temperature changes during charging and discharging. Film coating was performed using Coretech CT-AF300 to produce pouch films with varying ionite content and particle size. The influence of plasma treatment on the surface condition of PET film, aimed at improving coating adhesion, was also examined to derive optimal manufacturing conditions. Furthermore, the temperature characteristics of the pouch film during charging and discharging were investigated using an infrared thermal imaging camera and a self-developed test apparatus, respectively, to assess the feasibility of developing next-generation high-performance pouch films. Translated with DeepL.com (free version)

The accelerator pedal of a KLTV was applied in the form of a carryover utilizing the products of a civilian vehicle. there was case in which it was damaged because it did not reflect the military's specificity, Therefore the material and shape of the accelerator pedal were improved to confirm the strength improvement effect of about 86%, it can prevent accidents and contribute to securing mobility by presenting and applying fracture strength standards suitable for the military operation environment.

This study was conducted to verify the structural stability of the chassis frame of the 7M electric low-floor bus. The chassis frame model was analyzed under its own weight and external loads to determine deformation and stress distribution. A finite element method (FEM)-based structural analysis was performed to verify the strength and durability of the chassis frame assembly components. The analysis results identified the maximum stress values and their locations throughout the system. Furthermore, considering the differences in materials used in each component, the maximum stress values for each component were individually calculated. Comparing the maximum stress values with the yield strength of each material confirmed the structural stability of the designed 7M electric low-floor bus chassis frame.

In the modern logistics industry, the dual challenge of improving sorting efficiency and ensuring worker safety is paramount. This study presents an integrated smart factory solution developed during a first-year capstone design project. The system utilizes dual top-view AI vision cameras to classify items by grade and type in real-time, coupled with an Arduino-based sorting mechanism. A critical feature of the system is its proactive safety protocol, which employs AI algorithms to detect human presence in hazardous zones and triggers an immediate emergency stop. Experimental results from the prototype demonstrate high classification accuracy and robust safety responsiveness, suggesting a viable model for small-scale automated logistics environments.

Despite the rapid proliferation of electric vehicles, charging infrastructure lags behind, with existing wired methods posing safety and convenience challenges. This paper proposes a wireless charging station system to establish a new charging paradigm. By enabling charging through simple vehicle stoppage without cable manipulation, the system significantly enhances user accessibility. A prototype, constructed using Arduino and sensors within a solar-powered station design, validates the concept. The results confirm the feasibility of a sustainable charging ecosystem adaptable to future mobility advancements, such as autonomous driving.

Plastic resin is used to connect barrel to nozzle in injection unit. screw stroke, injection cylinder body pressure and barrel temperature are the most important terms of injection unit, interval linearity and repeatability to each term are analyzed here. Barrel temperature is analyzed according to the repeatability of the thermocouple at 150℃ using precise oven. The result temperature is within ±0.5℃ The standard deviation of barrel temperature shows 0.12~0.15, which being present as accurately during the test. Also measurement uncertainty was calculated regarding temperature, humidity factors in order to verify the test consistency.

As the agricultural population ages and declines, the demand for mechanized equipment to reduce labor intensity has increased. This study presents the design of a lightweight electric transport cart that operates in accordance with the walking speed of elderly workers and evaluates its structural safety and driving feasibility. The target driving speed was set to 0.7 m/s, and the frame was designed using aluminum alloy 6061-T6 for weight reduction. Structural analysis using ANSYS under a payload condition of 20 kg showed that the maximum equivalent stress was 87.547 MPa, which is lower than the yield strength of the material. Subsequently, dynamic analysis considering unpaved road driving conditions was conducted using ADAMS, confirming that the cart reached the target speed of 0.7 m/s within 0.8 s under a driving torque of 3.0 N·m.

Recent trends in tactical vehicle development have focused on achieving a balance between protection and mobility through reinforced hull structures, modular armor systems, and advanced mission equipment. These developments have led to an increase in gross vehicle weight (GVW), consequently requiring higher engine performance to maintain adequate mobility. In Korea, the development of a 12-ton-class tactical vehicle is currently underway, and establishing design criteria suitable for domestic operational environments through the analysis of existing tactical vehicle platforms has emerged as an important task. Accordingly, this study conducts a comprehensive survey of international tactical vehicle development cases and analyzes their operational roles, technical characteristics, and development backgrounds in order to construct a reference database applicable to the development of domestic medium-class tactical vehicles. In addition, the relationships among GVW, engine power, and power-to-weight ratio (P/W) are analyzed for the surveyed vehicles to identify technological trends adopted to compensate for increasing vehicle weight.

The MR fluid jet polishing process operates on the principle that the viscosity of MR fluid changes in response to a magnetic field. By applying a magnetic field during slurry injection, the fluid is consistently sprayed in a laminar, straight flow, with the nozzle diameter nearly matching the size of the injected fluid. This ensures stable, straight-line spraying, even when the injection height changes. The factors influencing material removal and surface roughness, which are indicators of the polishing rate, can be categorized into process parameters occurring during the polishing operation and the material properties of the workpiece. Due to the independent effects of numerous factors and the interactions between them, the polishing characteristics are highly complex, making it essential to understand the underlying polishing phenomena. To analyze the factors influencing the results, design of experiments (DOE) and regression analysis were applied. The results revealed that, in the MR fluid jet polishing process, the most significant factor affecting surface roughness is the feed speed, followed by injection pressure, and finally, the magnetic field.

The use of thin-film materials with micro- or nano-scale thickness has been increasingly adopted in the semiconductor materials field. Sputtering, a physical vapor deposition (PVD) technique, is widely utilized in various industrial applications as it employs plasma under vacuum conditions to transfer target materials onto substrate surfaces, thereby forming thin-film coatings. Owing to their significantly reduced thickness compared to bulk materials, thin films often exhibit mechanical properties that differ markedly from those of conventional materials. Consequently, an accurate evaluation of thin-film mechanical properties requires a thorough understanding of the substrate on which the films are deposited. In this study, aluminum (Al) thin films with thicknesses of up to 1000nm were deposited onto silicon wafer (Si-wafer) substrates using a sputtering system. The mechanical properties of the deposited thin films were evaluated through micro-Vickers hardness testing under various applied load conditions.

Flight training is a high-demand learning environment in which pilot trainees must acquire complex cognitive and psychomotor skills under time pressure. Building on prior evidence that training effectiveness is related to training schedules and perceived stress in naval fixed-wing pilot training, and motivated by recent work assessing student-pilot stress during initial flights using wristwatch-type heart-rate monitoring and heart-rate variability (HRV), this project aims to develop physiological indicators of flight stress based on heart-rate response patterns in pilot trainees during real training flights. We examine (1) phase effects, hypothesizing higher heart rate during takeoff and approach/landing than during cruise; (2) task-difficulty effects, expecting higher heart rate during high-difficulty training (e.g., repeated takeoffs/landings, upset recovery) than during basic maneuvers; (3) associations between post-flight subjective stress ratings and mean heart rate; and (4) experience effects, expecting lower heart rate among trainees with greater total flight time under comparable conditions. A three-year staged plan is adopted: Year 1 establishes wearable measurement and logging procedures; Year 2 expands data collection and tests hypotheses; Year 3 integrates findings into a preliminary evaluation model and a biosignal-based workload/stress assessment framework for training improvement.

With recent advances in autonomous flight, electric propulsion, distributed propulsion systems, and unmanned technologies, future air systems such as Advanced Air Vehicles (AAVs), Unmanned Aerial Vehicles (UAVs), and electric Vertical Take-Off and Landing (eVTOL) aircraft are rapidly emerging. However, existing airworthiness certification standards have been primarily developed for manned fixed-wing aircraft and therefore exhibit structural limitations when applied to these new classes of air systems. Conventional airworthiness criteria are largely based on pilot-centered operational assumptions, hardware-oriented safety verification, and test- and documentation-driven certification processes. As a result, their application to future air systems— characterized by autonomous flight software, electric and distributed propulsion, and hybrid civil–military operational concepts—may lead to excessive certification scope, inefficient verification processes, and extended certification timelines. This study analyzes the key technological characteristics of future air systems and systematically identifies the limitations of existing airworthiness standards from the perspectives of propulsion systems, flight control, software safety, and operational concepts. Based on this analysis, the study highlights the necessity of adopting performance-based and risk-based certification approaches and discusses preliminary directions for improving airworthiness frameworks suitable for future air systems.

By introducing an aptitude test, we can establish a measurement model that can select applicants with excellent flight aptitude, scientifically analyze the correlation with actual flight training, and supplement and develop a tool for evaluating flight aptitude through feedback to improve flight training programs. By selecting resources with excellent flight aptitude, we can lower the mid-course elimination rate in flight training courses, thereby securing the economic feasibility of pilot training, and ultimately, we expect to greatly contribute to aviation safety by training excellent pilots. It is expected to contribute significantly to this. The pilot aptitude assessment model can be utilized by airlines and educational institutions that train pilots as a tool for selecting students through admissions processes. Furthermore, it can help students identify their aptitude for aviation in advance and determine their career paths. Furthermore, pilot training institutions can utilize it to educate students and enhance the effectiveness of their educational investments.