Earticle

The increasing complexity of military aircraft systems has intensified the demand for more efficient and consistent airworthiness certification processes. In response, standardized parts—designed in accordance with international and national specifications—are being increasingly adopted to reduce redundant verification procedures and enhance the transparency and predictability of certification outcomes. This study investigates the role of standardized parts in military airworthiness certification, with an emphasis on their impact on certification processes rather than on component-level performance alone. A comparative analysis of certification frameworks in the United States, Europe, and South Korea is conducted to highlight variations in institutional structures, operational practices, and levels of digital integration. The analysis encompasses three key dimensions: technical factors related to verification reliability, organizational factors associated with documentation and data reuse, and economic factors involving testing and scheduling costs. The findings suggest that the use of standardized parts contributes significantly to minimizing redundant certification activities and facilitates the structured utilization of previously validated data. These characteristics form a practical foundation for transitioning toward digitalized certification ecosystems and for enhancing overall process efficiency in defense aerospace programs.

This study presents a formal attack trace on vulnerabilities such as DID-counter linked anonymity leakage in the baseline protocol through re-analysis of a privacy-preserving DID protocol. We propose improvements including enhanced session-key binding, mandatory multi-party trust establishment, blockchain-level token continuity verification, and event-based audit mechanisms. Simulation results confirm that the proposed protocol maintains throughput equivalent to the original while significantly enhancing privacy, auditability, replay detection, and forward secrecy.

The chain conveyor system is a product for the environment and productivity, allowing users to work efficiently. The existing chain conveyor system is operated by a single drive motor, so all processes are driven at the same time, so if the working hours are different, they are not time-efficient. Due to the nature of the chain conveyor system, a lubricant is used to prevent noise and dust caused by chain driving, and even if only one section of the chain conveyor breaks down, the entire line must be stopped in order to repair it. This study was conducted with a focus on localizing the flexible drive system, securing the reliability of the drive wheel that operates smoothly even in fatigue situations, prototyping and performance evaluation of the flexible drive system.

This study examines how parts standardization policies affect the quality of airworthiness certification. While standardization enhances efficiency and compatibility, it may conflict with safety-based certification criteria. By analyzing domestic and international cases, the study reveals structural misalignments that can lead to certification delays and test inconsistencies. Key findings highlight the need for performance-based certification, standardization frameworks aligned with safety requirements, and a feedback mechanism between policy and certification processes. The proposed improvements aim to ensure both safety assurance and industrial efficiency. This research provides actionable insights for regulators and industry stakeholders in aviation safety policy.

Bitumen produced from Steam-Assisted Gravity Drainage(SAGD) and Expanding Solvent Steam-Assisted Gravity Drainage(ES-SAGD) processes contains highly viscous emulsions with finely dispersed water droplets and suspended solids, resulting in poor oil–water separation performance. Conventional separation technologies, including Free Water Knockout(FWKO) vessels and Electrostatic Oil Treaters, have limitations in removing fine water droplets and suppressing rag-layer formation under high-viscosity conditions. To address these limitations, this study proposes a hybrid oil–water separation system integrating Electric Grid-based electrostatic coalescence with Microbubble-assisted flotation. The proposed system combines emulsion destabilization by microbubbles with electrostatic droplet coalescence to enhance gravitational separation. An engineering design framework, including operating conditions, electric-field configuration, and microbubble injection strategy, was established for application to ES-SAGD production facilities. To provide quantitative engineering validation, a theoretical analysis based on Stokes' law was performed. Under the assumed design conditions, doubling the water-droplet diameter increased the calculated settling velocity by four times, while reducing the microbubble diameter from 300 to 100 decreased the theoretical rising velocity to approximately one-ninth. These results support the engineering feasibility of the proposed hybrid separation mechanism. The proposed system provides a theoretical engineering design basis for pilot-scale implementation and offers a technical foundation for future experimental validation and AI-assisted intelligent bitumen separation systems.

Medical Cyber-Physical Systems (MCPS) integrate IoT and cloud technologies for patient monitoring, requiring lightweight authentication. Nikkhah and Safkhani proposed LAPCHS, claiming formal security validation. This study re-examines LAPCHS, identifying three unresolved weaknesses: anonymity leakage via SID-MT1 dependency, desynchronization attacks by blocking AT4 updates, and tag impersonation risks from weak x'⊕y' masking. Equation-based attack traces explain each vulnerability. To mitigate these, we propose a redesigned MT1 with session randomness, a commit-and-confirm update procedure, and strengthened dual-masking for x'. Simulations confirm the improved protocol preserves lightweight costs while enhancing anonymity, synchronization resilience, and impersonation resistance. Keywords: RFID Authentication; MCPS; Cloud Healthcare; Lightweight Protocol; Vulnerability Analysis.

In this study, we successfully fabricated highly stable and transparent gold (Au) metal mesh electrodes via an electrohydrodynamic (EHD) jet printing process for transparent display applications. To overcome the structural fragility and high sheet resistance of conventional indium tin oxide (ITO) electrodes, a low-cost, solution-processed EHD printing approach was introduced to form ultra-fine Au grid lines under ambient conditions. The geometrical dimensions of the mesh structure, particularly the grid pitch, were systematically optimized to investigate the trade-off relationship between optical transmittance and electrical sheet resistance. The optimized Au metal mesh electrode, featuring a line width of 3 ㎛ and a grid pitch of 200 ㎛, exhibited a low sheet resistance of 5.1 Ω/sq and a high visible-light transmittance of 86.2% at 550 ㎚, yielding an outstanding figure of merit (FoM). Furthermore, by incorporating a 15-degree tilted grid design relative to the underlying pixel display array, the critical optical issue of Moire interference fringes was completely eliminated, securing excellent invisibility. Long-term environmental reliability tests conducted under harsh conditions (85°C and 85% relative humidity) demonstrated that the printed Au mesh maintained its initial resistance with a variation of less than 3% after 200 hours, whereas conventional silver nanowire electrodes suffered severe degradation. These results indicate that the EHD-printed Au metal mesh transparent electrode holds great potential as a robust and high-performance alternative to ITO for next-generation large-area transparent and flexible optoelectronic devices.

The chain conveyor system is a product for the environment and productivity, allowing users to work efficiently. The existing chain conveyor system is operated by a single drive motor, so all processes are driven at the same time, so if the working hours are different, they are not time-efficient. Due to the nature of the chain conveyor system, a lubricant is used to prevent noise and dust caused by chain driving, and even if only one section of the chain conveyor breaks down, the entire line must be stopped in order to repair it. This study was conducted with a focus on localizing the flexible drive system, securing the reliability of the drive wheel that operates smoothly even in fatigue situations, prototyping and performance evaluation of the flexible drive system.

In modern mechanical design environments, frequent design changes make maintaining consistency between CAD data and BOM(Bill of Materials) a significant challenge. In Excel-based BOM management environments, designers often need to manually update 3D assembly models and 2D drawings whenever component information changes, leading to human errors and increased design lead time. This study proposes a reverse data synchronization automation system integrating the CATIA Automation API with Excel macros. When a BOM is modified, the system automatically detects and applies the changes. Using the NewFrom method and a recursive traversal algorithm, the assembly structure can be safely regenerated without reference-link breakage. Experimental results using an assembly model with 72 sub-components showed that the time required for design modification and drawing updates was reduced from approximately 60 minutes to under 2 minutes, achieving about 97% time savings. In addition, the system prevented title block input errors and reference-link failures, ensuring data integrity. The proposed framework provides a practical and cost-effective alternative for implementing a Digital Thread environment without expensive PLM(Product Lifecycle Management) systems.

Finite element analysis is widely used to predict the stress and deformation behavior of structures, but constructing analysis models and assigning boundary conditions require specialized expertise, limiting accessibility for non-experts. Recently, AI agents based on large language models (LLMs) have been actively studied. However, commercial LLMs cannot access confidential corporate data. They also carry the risk of hallucination, where incorrect values may be reflected in the analysis results. In addition, security concerns often prevent their use with proprietary design data. To address these limitations, this study employed open-source LLM that can be operated within a closed network, to automatically extract design conditions from natural language input, and introduced a parsing and validation procedure to prevent hallucination-induced errors. The validated data were reflected in the analysis model by precisely substituting only pre-defined tagged variables within the pre-processing python script, thereby modifying the model without altering the remaining script structure. The proposed system was applied to a case study involving the design modification of robot arms in a multi-joint robot used for ship-building industry; the cross-sectional shape, length, and material of the robot arms specified through natural language input were accurately reflected in the generated script, while unintended parts remained unchanged. These results demonstrate that users without expertise in finite element analysis can modify analysis models and obtain results solely through a conversational interface.

In this paper, to secure the accuracy and real-time performance of the perception stage in autonomous driving, frame alignment was performed using a homography transformation technique. an efficient dataset was constructed based on normalized bounding box formats by applying the YOLOv5 architecture as an object recognition model. The trained PyTorch model was optimized for the EN675 NPU accelerator environment, enabling stable real-time detection and tracking of six major road objects(up to 32 objects per frame) across four channels of full HD camera inputs. This study is expected to provide high computational efficiency and reliability for edge devices in real-time autonomous driving applications.

Suppressing underwater radiated noise (URN) is critical for naval anti-submarine warfare (ASW) survivability. High-heat shipboard cabinets use densely packed cooling fans, but their synchronous operation superimposes harmonic forces, generating a critical structure-borne tonal peak. This study analyzes anechoic chamber data from a 12-fan array, revealing that 2X torque ripples of BLDC motors concentrate within the 125 Hz resonance band of an panel, producing a 50.0 dB peak. To mitigate this, a Differential Speed Dispersion Control (DSDC) is proposed, enforcing a 3% speed deviation among adjacent fans. By inducing phase desynchronization (incoherent addition), an analytical power sum model predicts an 8.5 dB attenuation of the 125 Hz peak. Although accompanied by a minor airborne noise penalty (+0.64 dB), this study analytically validates DSDC as an effective trade-off strategy for maximizing acoustic stealth.

Recently, unmanned aerial vehicles have been widely used in various military operations, such as surveillance, reconnaissance, and communication relay missions, and the reliability of the datalink between the aircraft and ground control equipment is essential for stable mission operation. A ground antenna assembly controls the azimuth and elevation angles of the antenna based on aircraft position data and monitors the status of major components, such as the LNA and encoder, through BIT. However, false alarm cases were identified during operation and inspection, in which BIT errors were reported even though no actual failure had occurred. The main causes were analyzed as the LNA BIT result processing method, the accumulation condition for identical encoder values, and the error counter processing method that did not consider the antenna operating state. In this study, the LNA BIT decision logic was modified so that the BIT result is reflected in the actual status value, and the encoder BIT logic was improved to consider data validity, motor control voltage, and antenna operating state. In the improved logic, identical encoder values received while the antenna is idle are regarded as normal position holding, abnormal encoder data are excluded from identical-value comparison, and the error counter is controlled only under valid operating conditions. The test results showed that the proposed logic suppressed false alarms under normal idle conditions while detecting encoder abnormalities during operation and cable disconnection conditions, thereby improving the reliability of BIT decision-making and the operational stability of the ground antenna assembly.

This study presents an open-source aero-stealth design exploration framework for a low-observable cranked-lambda delta-wing UAV. Inboard and outboard leading-edge sweep angles are used as design variables, while an upper bound on an average radar cross section metric is imposed as a constraint. Aerodynamic performance is evaluated with OpenVSP and VSPAERO by computing lift-to-drag ratio over an angle-of-attack range. Stealth performance is assessed with PyPOFacets electromagnetic scattering analysis to estimate average RCS over multiple observation directions. The analyses are coupled through an automated workflow that shares a single geometry definition and consistently aggregates objectives and constraints, reducing errors from manual file handling and data conversion. A multi-objective optimization loop executed in RCE maps trade-offs and generates candidate designs for conceptual-stage decision making.

It is generally accepted that seawater transmits sound over longer distances than freshwater. However, whether this general explanation applies equally to aircraft noise generated in the air has not been sufficiently examined. In this study, the acoustic transmission characteristics of freshwater and seawater were compared under identical conditions, and the influence of SOFAR (Sound Fixing and Ranging) channels and shallow-water acoustic waveguides in marine environments was investigated. The analysis conditions were set to identical water temperature, pressure, frequency, and sound source; freshwater was set to a salinity of 0.1 PSU, while seawater was set to approximately 34 PSU, which is the average surface salinity of the South Sea of Korea. Additionally, low-frequency and general transmission characteristics were compared by applying 250 Hz and 1,000 Hz, which are representative frequencies of aircraft noise. The analysis results showed that the differences in sound speed and acoustic impedance between freshwater and seawater under identical conditions were not significant. Furthermore, it was found that the long-distance sound transmission characteristics of the ocean are primarily governed by oceanic environmental conditions, including water depth, temperature, pressure, and seabed topography, rather than by the physical properties of seawater itself. Meanwhile, since aircraft noise originates in the air and most of its acoustic energy is reflected at the air-water interface, the amount of acoustic energy entering the water was found to be very limited. Consequently, the influence of SOFAR channels and shallow-water acoustic waveguides on the underwater transmission of aircraft noise was found to be very limited. Consequently, the likelihood that aircraft noise generated in the waters around Gadeokdo will be transmitted over long distances across the Korea Strait and cause widespread impacts on marine life is low. In conclusion, even when considering SOFAR channels and shallow-water acoustic waveguides, the conclusion of previous studies that the underwater impact of aircraft noise is limited remains valid.

This study evaluates the structural integrity of the Control Rod Drive Mechanism (CRDM) housing, a critical pressure boundary component of the innovative Small Modular Reactor (i-SMR). A thermal-structural coupled analysis was performed under operating conditions of 15.5 MPa and 325°C for a 10 mm thick baseline model. The maximum deformation was 2.50 mm at the top, primarily driven by axial thermal expansion (+2.48 mm). Stress linearization confirmed a dominant membrane stress of 112.85 MPa, with a combined stress () of 116.27 MPa. This result ensures a safety factor of 2.42 against the ASME allowable limit ( = 282 MPa), quantitatively verifying the structural stability of the current i-SMR CRDM housing design.

This study evaluates the structural integrity and design optimization of the i-SMR CRDM housing under operating conditions (15.5 MPa, 325°C). Using a thermal-structural coupled FE analysis, a parametric study was conducted by varying the housing thickness from 10 mm to 3 mm. Results showed that while radial deformation remained stable (~0.33 mm) due to thermal expansion, axial displacement increased by 17.1% as thickness decreased. Stress linearization, based on ASME Section III NB-3200, identified 4 mm as the critical minimum thickness, yielding a combined stress () of 275.24 MPa, which satisfies the shakedown limit () of 282 MPa. In contrast, the 3 mm model exceeded the limit at 357.62 MPa. The baseline 10 mm design exhibited a high safety factor of 3.21, confirming its conservative reliability. These findings provide a quantitative basis for the lightweight design of SMR pressure boundaries while ensuring strict nuclear safety standards.

Al5083 aluminum alloy is widely used for ship hull structures owing to its high specific strength and excellent corrosion resistance; however, conventional arc welding involves high heat input, which induces welding distortion and degrades the mechanical performance of the joint. In this study, a parametric case study on laser welding of Al5083 butt joints was conducted with laser power, welding speed, and wire feed rate as key process variables. Bead geometry and back-bead integrity were evaluated for nine conditions, and the optimal condition was determined to be a laser power of 0.5 kW, a welding speed of 40 cm/min, and a wire feed rate of 30 mm/min. Under this condition, the tensile strength and elongation of the welded joint decreased to approximately 63% and 25% of the base-metal values, respectively, and the tensile energy decreased to approximately 39%. High-cycle fatigue tests yielded S–N relationships of =6.59×102·Nf−0.114 for the base metal and =3.67×102·Nf−0.106 for the welded joint, indicating a fatigue-strength ratio of approximately 0.60–0.65. This ratio provides a rationale for applying a reduction factor to the base-metal S–N curve in the fatigue design of laser-welded Al5083 structures.

In this study, the effect of underwater hydrofoil was analyzed on a electric propulsion high speed motor boat by model test at a high speed water tank. The hull floating and resistance performance according to the longitudinal position, area and angle of attack of the foil with the same cross sectional shape were analyzed and the required power was estimated. Through this study, it was confirmed that the longitudinal position of the foil significantly affects hull floating and resistance performance. The reason is that the moment increases as the foil position moves farther away from the hull center. If the hull floats at a relatively low speed, a sudden change in trim may occur. After the hull floating, a rapid reduction in required power occurs because resistance acts only on the foil and strut.

Digital transformation significantly impacts airport operations and operational efficiency; in particular, the implementation of digital identity recognition technologies, including biometrics, has emerged as a core driver of innovation. Reflecting this trend, Incheon International Airport introduced the "Smart Pass" system in 2023, aiming to enhance operational efficiency and service satisfaction by improving passenger flow. Contrary to expectations, however, the current utilization rate of the Smart Pass remains low, and the adoption rate among foreign visitors is particularly critical. Accordingly, to vitalize the utilization of the Smart Pass, this study analyzes users' intentions to accept digital technology. Specifically, a comparative analysis was conducted using 762 valid samples from Chinese and Japanese passengers, the top two nationalities by visitor volume, to examine the effects of passenger characteristics and psychological factors (perceived time) on digital technology acceptance. The empirical results demonstrate that prior digital technology experience, passenger characteristics, and perceived time significantly influence technology acceptance. Furthermore, noticeable differences in technology acceptance were observed based on the passengers' nationalities. These findings suggest that for a successful vitalization of digital identity recognition technology, airport operators need to implement segmented digital transformation strategies tailored to specific passenger characteristics.

The bearing reaction test is the final verification process to confirm whether the shafting system has been correctly installed according to the offset proposed by the designer, where the bearing reaction force must be estimated using the reaction force measured at the position of the hydraulic jack. Therefore, the purpose of this study is to perform shaft analysis for a 50MW class system and present a correction factor to determine the bearing reaction force at the measurement location. Additionally, when calculating bearing reactions by multiplying the correction factor, if any bearing fails to meet the constraints, it is necessary to readjust the bearing height. Another objective of this paper is to provide the reaction influence number, which represents the change in reaction force of a bearing and its adjacent bearings when the height of each bearing is raised or lowered by 0.1 mm, enabling installation workers to perform readjustments effectively. If it consists of twelve 50MW units, it will break the Guinness World Record for the world's largest diesel power plant.

In this study, high heat sealing temperature of cast polypropylene films for packaging secondary battery cathode materials, contamination of cathode materials due to low molecular weight additives, and the adhesion of fine metal foreign matter adsorption due to static electricity generation were improved to 8.5 N/25mm in multi-layer co-extrusion technology and non-migration 3-layer polyethylene PE-based composite film. securing a core layer tensile strength of 22.8 MPa and a Vicat softening point of 132℃ securing 40.5 N/25mm based on metallocene PE of the Skin-2 layer, a surface resistance rate of 5.73×1012Ω/sq, and a friction coefficient of 0.88 and significantly reducing adsorption of magnetic foreign substances to less than 5.3 to prove high-temperature heat sealing and non-migration 3-layer polyethylene PE-based composite film that can confirm strength retention rate of 95% or more even after exposure to high temperature and high humidity environment.

The commercialization of urban air mobility (UAM) requires a pilot certification framework tailored to powered-lift aircraft, which combine the characteristics of airplanes and helicopters. In October 2024, the U.S. Federal Aviation Administration promulgated SFAR 120 (14 CFR Part 194), a ten-year special regulation that establishes a powered-lift category rating combined with aircraft-specific type ratings and permits initial training in aircraft equipped with a single set of functioning flight controls. The European Union Aviation Safety Agency, by contrast, requires a pilot type rating for VTOL-capable aircraft on the basis of existing licenses, with customized syllabi combining helicopter, airplane, and powered-lift elements. In Korea, the Aviation Safety Act does not yet define a certification category for UAM aircraft, and the Act on Promotion and Support of Urban Air Mobility regulates only operator designation requirements. This study compares the finalized U.S. and European frameworks, identifies the regulatory gap in Korea in light of the pilot operation model announced by the Ministry of Land, Infrastructure and Transport in July 2026, and proposes a phased introduction plan consisting of a new certification category with concurrent type ratings, a time-limited special regulation for the initial cadre of pilots, and conversion pathways for existing commercial pilots.

In this paper, the effects of superheat, subcooling, evaporating, condensing temperature, cascade evaporating temperature, compression efficiency, etc. were analyzed for the optimal refrigerant charging of a R744-R717 cascade refrigeration system. Refrigerants used in the cascade refrigeration system are R744 in the low and R717 in high temperature cycle. The main results are summarized as follows : The mass flow rate ratio increases with increasing subcooling, superheating degree, compression efficiency and condensing temperature in the high temperature cycle. And the mass flow rate ratio decreases with increasing temperature difference of cascade heat exchanger and evaporating, cascade evaporating temperature. It was confirmed that the mass flow rate ratio due to superheating, subcooling, condensing, evaporating temperature, temperature difference of cascade heat exchanger, compression efficiency and etc., affects the performance coefficient of the cascade refrigeration cycle of R744 and R717, and it was found that for each of these factors, there exists a mass flow rate ratio for optimal refrigerant charging that maximizes the performance of the cascade refrigeration cycle.

This study designed an in situ XRD jig for lithium-ion battery electrode analysis and evaluated its preliminary XRD applicability under different static sample configurations prior to operando charge–discharge measurements. The developed jig was designed with an X-ray transmission window at the upper part so that X-rays could be directly irradiated onto the electrode surface. It was fabricated by considering electrolyte sealing, electrode fixation, electrical contact stability, and repeated assembly reliability. To verify the XRD applicability of the jig, spinel-structured Li4Ti₅O12, which has excellent structural stability, was used as a reference active material. The XRD results showed that the characteristic diffraction peaks corresponding to the spinel structure were clearly observed in both the Li4Ti₅O12 standard sample and the powdered active material. In the composite electrode, the main peak positions of the active material were maintained, although peak intensity decreased and background signals increased due to the influence of the conductive additive and binder. In the film-attached electrode, X-ray absorption and scattering by the film caused partial peak attenuation and increased background signals. However, the main peak positions remained unchanged, indicating that the crystal structure of the active material was preserved. In the electrode equipped with a beryllium window, strong additional diffraction peaks originating from beryllium were observed together with the diffraction peaks of the active material. The origin of these peaks was confirmed through XRD analysis of the beryllium sheet alone, demonstrating that prior measurement and correction of background signals from the window material are essential for accurate in situ XRD analysis. Overall, the developed in situ XRD jig was able to reliably detect key crystallographic information from lithium-ion battery electrode active materials. The results confirm its potential as an experimental platform for future analysis of peak shifts, phase transitions, and lattice changes during charge and discharge processes.

This study developed a combustion test model intended for eco-friendly marine fuels and evaluated its basic operating characteristics using kerosene as the reference fuel. The model consisted of a 512L combustion chamber, a gun-type burner, a three-compartment fuel tank, a fuel flame demonstrator, and a GL860 data logger. Combustion tests were conducted at fuel supply pressures of 7.4 and 8.4bar and blower motor frequencies of 36–60Hz, corresponding to load settings of 60–100%, for 900s per condition. At 7.4 bar, increasing the blower load from 60% to 100% reduced the RT3 temperature from 317.17℃ to 300.76℃ and the exhaust gas temperature from 228.00℃ to 210.65℃. Similar trends were observed at 8.4bar, although the chamber temperatures were generally higher than those at 7.4bar. High-temperature regions were consistently observed near RT3, RT5, and LT2, while the chamber pressure remained approximately −0.01bar under all operating conditions. The results demonstrated stable model operation and simultaneous temperature and pressure measurement within the tested range, providing baseline data for future comparative combustion tests using MGO and biofuel blends.

Maintaining stable operation of battery swapping stations under time-varying demand is a critical issue in Advanced Air Mobility (AAM). This study proposes a stepwise capacity expansion strategy in which pre-secured standby swapping channels are sequentially activated when either queue length or longest waiting time reaches a predefined threshold. The main comparison was conducted between a two-channel fixed-capacity configuration (Fixed-2) and the stepwise expansion configuration (Stepwise), while a three-channel fixed-capacity configuration (Fixed-3) was additionally used as a benchmark. Using common random numbers, 100 simulation replications were performed under identical demand and operating conditions. Compared with Fixed-2, Stepwise reduced average waiting time by 88.48%, waiting probability by 50.80%, and average queue length by 88.76%, while throughput remained nearly unchanged. In the paired comparison, Stepwise showed a lower average waiting time in 99 of 100 replications and the same value in one replication. Sensitivity analysis showed that lower threshold values activated channels earlier and improved waiting performance, but increased the number of active channels. These findings indicate that stepwise activation can effectively mitigate congestion under model-based time-varying demand, although the threshold values should be interpreted as operating reference conditions rather than universal optima.

A recent residential environment has developed highly dense around at the public roads mainly as the ease of access and convenience of transportation. Due to the development of lifestyle of above reasons, human beings are facing a noise problems caused by road traffic. In this study, investigated a automotive tire noise contribution at the Vehicle Internal and External by actual test using Electric Vehicle(EV) which have been developing and selling actively in recent years. And identified a tires & road noise characteristic and pure tire noise that excludes the Powertrain & Exhuast sytem noise. As a following steps, predicting a Pass-by Noise by using the identified tire noise level that measured on actual test and based on the Pass-by Noise prediction to figured out a noise influence with noise contour map of tire noise on the city environment through the computer simulation.

This study conducted a numerical investigation into how air inlet temperature and relative humidity impact the performance of a polymer electrolyte membrane fuel cell (PEMFC) system specifically designed for compact firefighting special trucks. A PEMFC stack model was created using Simcenter AMESim, analyzing the characteristics of cell voltage, stack power, and heat generation across air inlet temperatures from 50 to 90℃ and relative humidities ranging from 30 to 100%. The results showed that cell voltage and stack power varied nonlinearly with air inlet temperature and relative humidity, exhibiting greater temperature sensitivity under high-humidity conditions. In the high-temperature and high-humidity region, voltage and power tended to decrease, possibly due to reduced oxygen partial pressure and water accumulation. Relatively high stack performance was achieved at 70–80 °C and 50–70% RH, indicating that both parameters should be considered simultaneously when optimizing operating conditions. These results highlight the strong interaction between air inlet temperature and relative humidity as critical operating parameters that influence PEMFC performance, emphasizing the need to consider both factors simultaneously for optimizing operating conditions.

This study presents the design and performance evaluation of a high-efficiency hybrid gearbox for Light Sport Aircraft (LSA) to meet the demand for eco-friendly propulsion. The system optimizes power distribution between the internal combustion engine and electric motor to ensure high operational efficiency and smooth power delivery. By integrating a one-way clutch, the design enables seamless power transitions and prevents mechanical interference between the dual power sources. Operational reliability is further enhanced through an ECU-integrated control algorithm and an AI-based predictive maintenance model for real-time system monitoring. Experimental bench tests demonstrated a stable power output of 120HP, successfully fulfilling the rigorous performance requirements of LSA-class aircraft. This research provides a critical technical foundation for localizing hybrid propulsion systems and advancing the development of next-generation smart aviation technologies.