Earticle

This study evaluates the structural stability of a hydrogen shut-off valve used in fuel cell electric vehicles (FCEVs) under extreme operating conditions, including high pressure and cryogenic temperatures. Using a one-way Fluid-Structure Interaction (FSI) analysis based on ANSYS CFX and Static Structural, the study simulates thermal and pressure loads on key components. The results show that the maximum equivalent stress occurs in the rod (361.22 MPa), while safety factors for all components remain above 2.11, confirming adequate structural integrity. In order to secure higher structural stability and reduce the weight of parts, attention should be paid to the selection of materials and improving the shape. The findings provide a valuable basis for improving the design reliability and optimization of hydrogen shut-off valves for future automotive applications. The leak tightness and durability tests of the hydrogen shut-off valve under cryogenic conditions verified its structural integrity, confirming its safety even after more than 5.2 million repeated operations.

Priority should be considered to encourage businesses to participate by activating the low-noise machine certification system. However, the domestic low-noise machine certification system has not yet been significantly activated. There is a need for a system that only products that meet the environmental sign certification standards for low-noise construction machinery are recognized as "low-noise machines". A compliance evaluation agency (CAB) in the field of low-noise equipment should be introduced in Korea to help facilitate international certification of domestic company products. Therefore, it is believed that it will help expand the supply of low-noise machines through technology development and export improvement.

Proton Exchange Membrane Fuel Cells (PEMFCs) are emerging as reliable energy conversion devices for stationary power generation due to their high efficiency and environmental benefits. However, achieving long-term durability remains a critical challenge for commercialization. This study investigates the performance and degradation behavior of a PEMFC stack under 360 hours of constant current operation at approximately 0.22-0.23 A/cm², delivering a stack output of 1.5 kW. Electrochemical Impedance Spectroscopy (EIS) was employed to diagnose cell degradation, revealing increases in ohmic and charge transfer resistances over time. The results highlight the importance of uniform cell performance within the stack to prevent output limitations. Furthermore, we propose a framework for Remaining Useful Life (RUL) prediction to enhance system reliability. Future work will focus on applying these diagnostic techniques under varied operating conditions and integrating machine learning for advanced predictive models, aiming to support the development of stable, long-life PEMFC systems for stationary energy applications.

The purpose of this study is to fabricate a multi-stage, variable-section and high-speed of the cutting device for recycling carbon fiber from waste hydrogen storage tanks. In this study, a high precision cutting device is fabricated utilizes (i.e., multi-stage, variable-section, high-speed cutting function and a diamond wire tool) to cut various waste hydrogen storage tank carbon fibers into scrap in a short period of time. The fabricated items include the development of diamond wire tools and wheels, cutting feed systems, structural frames, cooling system applications, and hydrogen tank fixing systems. The rotational speed of multi-stage wheel is in range of 0~600 rpm, and feed speed of diamond wire cutting tools is in range of 10–80 mm/min. The results showed that a new precision cutting device is able to cut the waste hydrogen storage tanks more than 400 pieces of performance indicator scrap (200×200 mm) within 8 hours of the cutting time. This confirmed that a new fabricated cutting device is a high speed cutting machine that is feasible for application in waste hydrogen storage tanks recycling in stead of conventional cutting device.

The K2 tank not only has excellent mobility but also has excellent protection performance. Armor steel is used to provide structural protection, and the turret structure is made of rolled homogeneous armor (RHA) plates. Most processes for fabricating structures involve welding, but RHA steel has the problem of being susceptible to thermal deformation. To compensate for this, a plan to apply the bending method was considered. In this study, prior to applying the bending method to an actual vehicle, mechanical property evaluations were performed on materials, welding, and bending specimens. It has been proven that the bending method can achieve performance equivalent to or better than the welding method. The verification tests included hardness tests, tensile tests, fatigue tests, and impact tests. All tests except the impact test confirmed that the bending method was superior to the welding method. In the case of the impact test, the impact value of the bending method was lower, but it satisfied the standard with a value higher than the minimum requirement according to the standard, so it is judged that there will be no problem in applying the bending method.

The center bearing of the propeller shaft in the KM-Sam mounted vehicle is a component that requires high durability due to high-speed rotation and it must exhibit strong resistance to vibration and strees. However some Republic of Korea Air Force (ROKAF) units have experienced failures where the center bearing bracket breaks, leading th the detachment of the propeller shaft assembly. This issue has only occurred with domestically developed center bearings, A root cause analysis confirmed excessive second-order components and stress, Therefore improved results were derived through comparative testing with imported parts, and the effectivenss was verified by applying them to actual vehicles.

This study presents a truck classification method using panoramic side-view images to meet the Ministry of Land, Infrastructure and Transport’s 12-category standard (types 4–12). The system captures a vehicle’s full side profile via a panoramic imaging device, ensuring complete wheel visibility. A YOLOv12-based deep learning model detects wheels, and image processing extracts their center coordinates. Pixel distances between adjacent wheels are calculated and normalized to determine axle spacing patterns, which, together with wheel count, are applied to a rule-based classifier. Tests on 1,200 real-world panoramic truck images (1,000 for training, 200 for testing) achieved a mean average precision of 96.1% for wheel detection and 90.5% overall classification accuracy. The method offers explainable classification through measurable structural features, supporting applications in smart tolling, road usage billing, overloading enforcement, and autonomous vehicle perception.

In this study, the shape of the exterior, not the inside of the product, was modified. Various exterior shape change plans were compared and reviewed through injection molding analysis, and among them, the most effective shape for suppressing warpage deformation was derived. The shape of the product was modified to optimize the bending deformation of the cover located at the top of the automobile battery case. The analysis was conducted under a total of three conditions, each of shape A, which is a rectangular parallelepiped shape at the top of the product, and shape B, which is concave on the side of the product. As a result of the study, both shape A and shape B were reduced compared to the amount of bending deformation of the original shape. Among them, shape B2, which showed the largest reduction, decreased by 82.096% from the amount of bending deformation of the original shape.