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Bayesian techniques are vital in mechanical manufacturing for uncertainty quantification and process optimization. This review explores their diverse applications, highlighting advantages in handling small data and incorporating expertise for improved decision-making in quality control, reliability, and machining. It also discusses integration with machine learning and applications in specialized areas. Future research should focus on Industry 4.0 integration and user-friendly tools, emphasizing Bayesian methods' role in intelligent manufacturing.

Most engines for small vessels operating in coastal waters, such as fishing boats, are equipped with a reduction gear to reduce the engine's rotational speed. Small vessels are equipped with engines of fixed output and reduction gears of single reduction ratio only. This paper is a study on the development of a two-stage reducer capable of controlling the reduction ratio according to the light and full load conditions of a ship. Because the torque and rotational speed delivered to the propeller can be flexibly adjusted, the engine load can be maintained appropriately. In addition, because the engine room space is limited, the development of a two-stage reducer with an integrated power take off (PTO) was pursued to minimize the volume. Through this development, we were able to confirm a reduction in fuel consumption rate because we did not have to consume a lot of fuel to maintain maximum output. Reducing fuel consumption can result in reduced harmful exhaust emissions. Additionally, it can be expected that the frequency of failures that may occur due to overload can be reduced.

In this study, static and dynamic analysis verification was performed to apply the fuel cell system to the E-PTO of the Wire aerial vehicle. First, structural analysis was performed to improve the weak points that occurred. Next, vibration analysis was performed on the fuel cell system for which structural safety review was completed according to the wide-band irregular vibration test standard. The analysis results showed that resonance occurred in a specific frequency band and local stress was high, so stiffness reinforcement was performed. After reinforcing the stiffness, stress was reduced through a decrease in transient response characteristics and resonance phenomenon.

Five novel miniature bipolar radiofrequency (RF) electrode tips with distinct tip geometries (spherical, flat, square, and 45° angled) were developed to enable high-precision tissue ablation. Performance was evaluated on saline-soaked tissue, ex vivo bovine liver, and porcine muscle under consistent RF power settings. All designs produced highly localized lesions only a few millimeters across, confirming precise ablation with minimal damage to surrounding tissue. Tip geometry influenced ablation efficiency: a 45° angled tip created ~5 mm lesions at lower power (highest efficiency), whereas an ultra-fine 1.0 mm tip produced ~1 mm lesions but required higher power. These results indicate that the new bipolar RF electrodes achieve precise, localized tissue ablation with minimal surrounding tissue damage and show promise for precise lesion removal in minimally invasive surgery.

This paper reviews ordinal decision tree algorithms for ordinal classification, exploring theoretical foundations, key algorithms (MDT, QMDT), specialized splitting criteria (Ordinal Gini, Weighted Information Gain), and ensemble methods. It discusses applications in healthcare and social sciences, highlighting interpretability and flexibility while acknowledging overfitting and instability. As implications for future research, this study points out advantages such as interpretability and flexibility, and limitations such as overfitting and instability.

This study was served as a foundational investigation about Cook-off phenomenon of a 7.62mm caliber machine gun. In this paper, the Cook-off phenomenon was described and the test precedure developed with reference to TOP 3-2-045 was introduced along with the test firearm. Through live-fire tests conducted according to the test procedure, changes in barrel temperature based on the number of rounds fired, as well as the peak temperature, were observed. The occurrence, time and temperature of cook-off were also identified. Lastly, an analysis of the derived test results was conducted, and the limitations of this study were discussed along with suggestions for future studies.

This study was carried out in a cold storage chamber with a floor space of roughly 3.3 square meters (1 pyeong). The findings revealed that the hybrid cooling system consumed a comparable amount of electricity to that of the conventional vapor compression system. This similarity in power usage can be attributed to the hybrid system’s operational strategy: thermoelectric modules were selectively activated during periods of frost accumulation, effectively minimizing the energy typically used for electric defrosting in vapor compression units. To advance the commercialization of this hybrid system in cold storage applications, several technical improvements must be considered in addition to cost optimization. First, the design should address the bulky nature of the heat exchanger setup. At present, the vapor compression and thermoelectric modules are housed in separate outdoor units; a more efficient approach would involve integrating them into a single, space-saving unit. Second, incorporating a water mist spray mechanism for the outdoor heat exchanger coil could enhance heat dissipation. This method, which leverages latent heat exchange, has demonstrated strong performance in other applications and merits further investigation for use in the proposed system.

Currently, the use of renewable energy is more encouraged because of its eco-friendly energy such as no emission gas and less environmental pollution. Hot water is needed in domestic affairs almost everyday. Solar collector are frequently used to obtain the hot water in case of renewable energy using Sun. This study aims to evaluate the characteristics of hot water acquisition using natural convection of solar collector through numerical analysis. As the results, as the temperature of heat source was increased, the turbulent kinetic energy and buoyancy gradient were also increased in case of no inlet flow. Enthalpy was more influenced by temperature than flow work. Furthermore it was necessary to increase the number of solar collector per module or decrease the inlet flow rate in order to acquire the satisfied hot water.

In the present numerical study, the optimal design of cooling fans for cooling towers was investigated. The key design variables selected were the pitch angle and twist angle of the cooling fan, with the pitch angle ranging from 0° to 20°, and the twist angle from 0° to 10°. The objective was to develop a cooling fan capable of actively responding to varying operating conditions; to this end, the twist angle was implemented as a variable camber at the blade tip. The analysis results showed that, under identical pitch angle conditions, increasing the twist angle tended to reduce the stall phenomenon of the cooling fan. Optimization was performed using the pitch and twist angles as design variables, and lift, pressure drop and torque as response variables. Under the specified operating conditions, a combination of a 5° pitch angle and a 10° twist angle yielded the best performance.

The world's largest diesel power plant listed in the Guinness Book of World Records is Jordan's Amman Asian power plant, which produces a total of 573 MW of electric power. It consists of 38 units of 15MW capacity, and KEPCO achieved high profitability through the power plant. If a large capacity of 50MW clsss is applied, it will be newly listed in the Guinness Book of World Records even if only 12 units are constructed. Therefore, large-scale overseas orders for diesel power plants that require large capacity are expected in the future. The purpose of this study is to derive a installation offset by performing the shaft alignment analysis for large capacity 50MW shaft system. As a result, the offset of shaft system for the 50MW diesel power generation equipment was successfully derived through the bearing influence assessment and introduction of arrangement slope for main engine bearings.

Aircraft Noise is a sound that humans do not want. In this study, based on the Rotax 914 engine used in Korea, the Propeller blade angle was changed by 1 degree for the 3-leaf “K company” Propeller and the 3-leaf “G” wooden Propeller, and the engine RPM was changed to examine the Noise and thrust changes. The purpose of this study is to check whether Noise and thrust loss are the least at the engine's maximum RPM, and to propose an aircraft operation plan in the noisy aerodrome area based on the values. This research further seeks to identify optimal propeller configurations that balance acoustic performance and thrust efficiency. The results are expected to aid in formulating guidelines for quieter flight operations near populated areas.

This study examines the impact of Propeller blade pitch angle mismatch on Noise, thrust, and vibration in light aircraft. Tests were conducted using a simulator with one blade set at increased pitch angles (10°, 12°, 14°) compared to the standard 8°. Results showed that mismatches increased vibration (above 0.26 IPS), Noise levels, and caused operational issues such as fuel leakage and backfire. While thrust initially increased with pitch, it dropped at 14° due to fuel flow instability. These results highlight the need for strict pitch alignment tolerances to ensure optimal performance and safety in aircraft maintenance and operation.

This study explores educational strategies for cultivating skilled professionals in Korea’s Urban Air Mobility (UAM) sector. Based on the national K-UAM roadmap, it identifies training needs across three core domains: operation, maintenance, and infrastructure. A structured survey was conducted with 62 organizations involved in UAM development. Results reveal a strong demand for simulation-based emergency response training, AI-assisted diagnostics, and smart infrastructure operation. Key barriers include the shortage of interdisciplinary professionals and insufficient practice-oriented curricula. Using DACUM and CDIO frameworks, this research proposes a modular, domain-specific education model. The findings serve as a foundation for establishing future UAM workforce policies and academic programs.

Overloaded and improperly loaded trucks cause serious road hazards, such as rollovers and cargo falls. Although automatic enforcement methods are being studied, they face challenges in accuracy and legal application. Thus, a technology for direct tracking and enforcement is needed. This study uses EfficientNet to extract features of vehicles and license plates, and applies cosine similarity to identify the same vehicle. Comparisons were divided into “same vehicle” and “similar vehicle,” with a threshold-based method and five classification types. Results showed that the average similarity of the same vehicle group was 0.11 higher than that of the similar vehicle group. The accuracy of correctly identifying the same vehicle was 84.54%. Integrating OCR or LPR is expected to further improve tracking performance.

This study developed a coupled fluid-thermal analysis method for a liquid hydrogen control valve system. Using ANSYS CFX, a transient CFD analysis was performed for the control valve system, including MLI, and the thermal analysis was linked to evaluate the insulation performance of MLI. The analysis examined the pressure distribution, turbulent viscosity, and heat flux at the inlet and outlet, revealing that the highest heat flux occurred in MLI 2. This research is expected to contribute to improving the thermal shielding performance and efficient insulation design of liquid hydrogen storage systems.

This study investigates the effects of various Throttle Position Sensor (TPS) signal anomalies and throttle body defects on automotive acceleration and safety by experimentally reproducing and analyzing eight distinct fault scenarios. The results demonstrate that the Electronic Control Unit (ECU) consistently detects signal anomalies and activates fail-safe modes, limiting throttle response and engine output to maintain automotive control. In all fault conditions, sudden unintended acceleration was effectively prevented, and braking performance remained unaffected. These findings underscore the robustness of the throttle control system against electrical and mechanical defects and offer valuable insights for the design of safer drive-by-wire systems.

The purpose of this study is to investigate the dynamic behavior of the internal cabinet of a nuclear power plant due to an earthquake and the characteristics of cabinet vibration reduction by TMD(tuned mass damper). For this purpose, the experimental device was constructed and numerical analysis was performed. The experimental device for the dynamic behavior of the cabinet consists of a cabinet, sliding base, mount, actuator, exciter, and measuring system, and the frequency response function of the cabinet was obtained. In addition, the time history of the cabinet was analyzed for acceleration and displacement through TMD design and cabinet 3D modeling. The natural frequency and response of the cabinet were lowered by approximately 26% due to the structural rigidity of the cabinet under the conditions of door opening and sliding base strong excitation. The acceleration and displacement characteristics of the cabinet varied depending on the TMD mass, and the cabinet vibration reduction effect was the best when the TMD mass was 60kg. The reduction in acceleration and displacement of the cabinet was approximately 12.1–16.2% and 10.1–19.1%, respectively.

This study investigated the operation status of major construction machines used in domestic construction sites and analyzed the characteristics of noise generated by these machines. In addition, we tried to understand the impact of construction machine noise on the working environment and the surrounding environment. As a result of the analysis, the noise level of the working breaker was the highest at 101.5 dB(A). This suggests that it can act as a major factor in the spread of noise to the residence around the construction site and the occurrence of civil complaints from residents. Therefore, this study is expected to provide a scientific basis for the noise problem of construction machinery and be used as basic data for effective noise management policies and system improvement.

This study simulated the thermal characteristics of a liquefied hydrogen (LH) tank with varying multi-layer insulation (MLI) thickness and surrounding conditions. A transient heat conduction simulation was conducted using ANSYS Fluent software to predict the temperature distribution of the LH tank. The LH tank is composed of carbon fiber reinforced plastic (CFRP), MLI, and an Air layer for thermal insulation. A large MLI thickness delayed temperature changes inside the MLI due to its low thermal diffusivity. And then, the temperature rapidly increased near the outer wall, resulting in thermal non-uniformity. Therefore, when designing a LH tank with MLI materials, it would be necessary to optimize the design (i.e., MLI thickness) by considering structural stability issues caused by thermal non-uniformity. In addition, as the surrounding temperature increased and the convective heat transfer coefficient became higher, the enhanced heat transfer led to a higher temperature gradient within the LH tank, bringing the outer wall temperature of the LH tank closer to the environmental conditions. The results of this study will significantly contribute to establishing a comprehensive thermal database for predicting the thermal-structural behaviors, considering the thermal stress induced by the thermal distribution of LH tanks, which depends on the installation conditions and environment.

This study evaluates how road profile and speed affect tire loads of a hydrogen tube trailer using MSC Adams/Car multibody dynamics simulation. A tractor and trailer loaded with 64 high-pressure cylinders were modeled, and four representative road profiles flat, pothole, short-wave, and long-wave were applied at 30, 60, and 80 km/h. Vertical tire load time histories were extracted for five wheel positions. Flat roads yielded stable loads matching static distribution. Potholes produced short, high-amplitude impacts (up to 120 kN at 30 km/h) with reduced peaks at higher speeds. Short-wave profiles caused severe asymmetric roll loads (67 kN at 80 km/h), while long-wave inputs generated smoother, moderate increases over longer durations. Load amplification diminished toward trailer axles due to suspension energy dissipation. The results inform structural design of tube trailers and development of speed-control or active load-mitigation strategies for autonomous hydrogen transport vehicles.

This study establishes a transient CFD and coupled CFD-thermal analysis method for evaluating the insulation performance of a liquid hydrogen control valve system incorporating an MLI-VCS-MLI configuration. Parametric analysis was conducted by varying the thickness of MLI 2 (50–200 mm) to assess its impact on the temperature distribution and heat flux within the valve body and insulation layers. The results indicate that increasing the thickness of MLI 2 significantly reduces heat flux and improves insulation effectiveness, with the highest heat flux occurring at the outermost MLI layer exposed to ambient conditions. These findings provide valuable insights for optimizing insulation design in liquid hydrogen storage and transport systems, contributing to enhanced thermal management and energy efficiency.

This study investigates the impact of solar paper panel tilt angles on the flight endurance of solar powered the drone. To address the limited flight time of conventional battery powered drones, photovoltaic solar paper panels were mounted at varying angles 0°, 15°, 30°, and 45° tested under consistent conditions. Experimental results showed that a 30° tilt angle produced the highest power output, leading to about 14% increase in flight duration compared to a flat configuration. These findings demonstrate that optimizing panel orientation significantly improves energy efficiency and drone performance. This work provides practical insight into the design of lightweight solar UAVs and highlights the feasibility of simple tilt adjustments as a low complexity alternative to active solar tracking systems.

This study quantitatively analyzed Buzz, Squeak, and Rattle (BSR) noises occurring during automotive operation and identified their root causes. Abnormal noises were initially detected during a first test drive and were classified into BSR types based on data from a Noise Observer system. Case analysis revealed that in the 2020 G model, a squeak noise was caused by friction between solid components due to durability degradation and damage to the suspension bushing. In contrast, the 2022 G model exhibited a rattle noise resulting from insufficient structural gaps. As modern vehicles continue to pursue higher performance, safety, and cabin quietness, the reduction in component gaps has increased the likelihood of BSR occurrences. This study demonstrates the effectiveness of diagnosing the root causes of BSR and confirms its practical value in reducing maintenance time and minimizing misdiagnoses.

This study proposes a hierarchical optimization methodology for two-stage gear systems using Monte Carlo enhanced Genetic Algorithm (MCeGA). The approach integrates reliability-based design with genetic algorithms to overcome the inherent randomness of traditional GA methods. A two-phase optimization framework was developed. The system incorporates Unity engine for real-time 3D visualization and interactive design evaluation. Key design constraints including contact ratio, gear ratio, and meshing conditions were parameterized according to ISO 6336 and AGMA 2101 standards. The proposed framework enables application-specific optimal gear configurations through Pareto analysis and weighted optimization, providing engineers with practical design solutions for various industrial requirements.

The thermal management of high-density electronics within military shelters is a critical challenge for ensuring operational reliability, particularly under harsh field conditions involving significant solar radiation. This study presents a numerical investigation using three-dimensional Computational Fluid Dynamics (CFD) to optimize an air-cooling system for an electronics rack housed in a military shelter. Four distinct cooling configurations were analyzed and compared: (1) a baseline model relying on natural convection, (2) a fan-assisted forced convection model, (3) a direct cold air supply model using an insulated duct, and (4) a hybrid model integrating both fans and the duct. Boundary conditions were established based on the high temperature and solar radiation criteria of the MIL-STD-810G standard. To quantitatively evaluate the cooling efficiency of each system, a normalized performance index derived from a weighted sum of the average temperature and temperature standard deviation was employed. The results demonstrate that the baseline configuration leads to critical overheating, with component temperatures reaching up to 124℃. In contrast, the hybrid fan-duct system exhibited the most superior performance, effectively reducing the maximum temperature to 59℃. This is attributed to a powerful synergistic effect, where the qualitative supply of low-temperature air via the duct is combined with the quantitative distribution of flow rate throughout the system by the fans. This study elucidates an effective thermal management strategy for electronics in military shelters exposed to severe environments, identifying the integrated fan-duct system as the most robust and optimal air-cooling solution.

In recent years, airport construction projects have been promoted in island regions such as Gadeokdo, Baengnyeongdo, Ulleungdo, and Heuksando. However, a systematic review of the potential impact of aircraft noise transmitted underwater on marine life remains insufficient. This study acoustically analyzes the transmission process of airborne noise generated by aircraft as it passes through the sea surface and enters the underwater environment. The physical mechanisms are examined with a focus on transmission loss, conditions for total internal reflection, and acoustic impedance differences. In particular, the theoretical transmission coefficients of sound pressure and particle velocity at the air–water interface are reviewed and compared to the auditory reception ranges of marine organisms to assess the potential for acoustic impact. The findings of this study can serve as foundational data for establishing coastal and island airport noise management standards and formulating marine ecosystem protection policies.

In this study, structural analysis was performed to select the optimal design shape through failure identification and design changes in turbine housing. Damage in the inlet flange is considered to be high cycle fatigue due to the vibration excitation in the engine full load test. Therefore, the FE analyses were performed natural vibration analysis and frequency response analysis for the initial shape and design change models. The stress magnitudes were obtained as a function of frequency through frequency response analysis according to engine vibration excitation. As a result, the dynamic stiffness of Case (1) increased by approximately 3.6% compared to the initial model, and Case (2) increased by 4.6%. In addition, the stress magnitude was greatly reduced in the design improvement. Therefore, the model with only the flange thickness increased is thought to be optimal design for securing the durability of the turbine housing.

The most basic control algorithm of the electric power steering system in the Korean refrigerating cart CoCo was first commercialized as a prototype in 2022 after the Motor Driven Power Steering (Electric Power Steering) was verified and applied to automobiles. In order to overcome the heavy load of small machines such as refrigerating carts weighing 750Kgf, the driver's great power is required, which can cause muscle skeletal disorders, causing many female drivers to complain of pain, and recently applied electric steering technology because it was urgent. In this study, we study a control algorithm that complements the stability of the existing control algorithm applied to the electric power steering device for electric carts and analyze and verify the steering performance of refrigerated carts through analysis using MATLAB/SIMULINK.

The purpose of this paper is to investigate the vibration phenomenon occurring in the structure such as a ship with the hemispherical substructure and operating at fixed frequency, and to suggest the active vibration control method using the Fx-LMS algorithm to reduce vibration amplification. In order to study the possibility of reducing vibration in the hemispherical structure, the active vibration control model was developed and a vibration control experimental device for the hemispherical structure was constructed. The narrowband Fx-LMS algorithm was developed to enable precise real-time control at a specific frequency, and the secondary path for dynamic control was modeled with two coefficients per frequency. The experimental device is equipped with three exciters, six 3-axis actuators, and six 3-axis error sensors, which can acquire 18 error sensor signals. Real-time secondary path tracking was possible with the secondary path consisting of two coefficients and the control algorithm, and effective vibration control performance was confirmed through this. And the experimental results of active vibration control of the exciter for three frequencies showed that the exciter vibration was reduced by a minimum of 63.7% and a maximum of 97.7%, which shows the possibility of reducing the vibration of the structure in real time using the proposed method.

This study investigates the vibration characteristics of an aluminum subframe for small and high-speed vessels through modal and resonance analysis using the finite element method (FEM). Due to the low stiffness and damping of aluminum, concerns arise over structural resonance and fatigue. A 3D model based on actual design drawings was analyzed to extract six natural frequencies and corresponding mode shapes. Significant deformation was observed in the first and second modes (90.65 Hz, 110.60 Hz), which may overlap with operational frequencies. The fifth mode (263.70 Hz) showed high amplitude with Y-axis concentration, indicating lateral resonance vulnerability. Deformation ratios were used to identify dominant vibrational directions. Based on the findings, design strategies such as structural reinforcement, RPM adjustment, and damping device application were proposed to improve vibration safety in the early design stage.