Electric kickboards provide personal mobility with a simple structure and easy operation. With these advantages, the number of users is increasing annually. However, as the number of users of electric kickboards increases, related accidents are also increasing. To prevent accidents, this study proposes the topological optimization of an electric kickboard connecting part to improve structural strength during a front collision. The results confirmed that as the volume fraction increased, the structure connecting the board and the bottom of the handle support changed to a toroidal shape, thereby lowering the maximum stress and improving the uniformity of the stress distribution. In addition, the topological optimization was safer than the connecting parts of two typical electric kickboards sold in the Korean market. These findings can contribute to improving the safety and optimizing the design direction of electric kickboards.

Movable weir is a major system used to manage water level in a river to secure drinking water, agricultural water, and industrial water. It is critical to safely construct and operate movable weir, in any environmental circumstances. In this study, we performed an unsteady flow analysis, on the movable weir with overflow water depth. The continuity equation, with constant density and incompressible Navier-Stokes equation, were used for the flow analysis. The CFD results were applied for structural analysis, to evaluate the safety of movable weir. According to the analysis results, the movable weir has secured sufficient safety.

High-strength steel, which has higher strength than ordinary steel, has emerged as a representative lightweight material because of its superior price competitiveness and easy application of manufacturing processes compared to other lightweight materials such as nonferrous metals and sandwich plates. Thus, the purpose of this study was to reduce the thickness and light weight of parts by applying high strength steel more than 600 MPa to various body parts. TR590 and DP590 high tensile steels were applied to the reinforcement seat belt front top and bottom components respectively. To this end, the impact simulation was performed, and the safety of the parts was investigated through FE-Analysis. Prototype molding evaluation confirmed the possibility of mass production of reinforcement seat belt front upper and lower components, using high tensile steel.

A fixing frame applied with Foam Cored CFRP Sandwich Composite (FCCSC) that replaces SAPH440 steel used in the fixing frame for hydrogen storage was designed, and its structural safety was evaluated. In the design of the fixing frame, FCCSC was implemented by PMI foam core, a Bakelite mount, and Carbon Fiber Reinforced Plastics (CFRP) using woven carbon fiber prepreg. Unlike the steel fixing frame, the FCCSC-applied fixing frame had a cross-section of hollow-rectangular, and its validity was confirmed through finite element analysis. Structural analysis of the designed FCCSCapplied fixing frame and steel fixing frame was performed. Under the extreme load condition of 9G acceleration, the steel fixing frame showed the lowest safety factor of 1.14 based on the yield strength in the opposite direction of gravity. On the other hand, the FCCSC-applied fixing frame showed a safety factor of 7.6 at the maximum principal stress and 3.15 at the shear stress. Through this result of structural analysis, it was verified that the FCCSC-applied fixing frame, which was 25.8% lighter than the steel fixing frame, was 1.8 times safer.

Plastic deformation of balls in safety coupling by collision with V-Hole was investigated in the current study. Generally, when the applied torque is greater than the maximum allowable torque, balls in V-Hole get out from the holes and the coupling loses the torque transfer capability. After balls are out from the V-Holes, the balls and V-Hole rotate at a different velocity. When balls meet the next V-Hole, they collide into the wall of the V-Hole. Due to this collision, plastic deformation and wear take place. The plastic deformation and wear may reduce the torque transfer capability of the safety coupling. The reduction in torque transfer capability was observed in the experiment. In this study, plastic deformation of balls and flange was investigated through dynamic analysis of the safety coupling. Also, the effect of relative rotational velocity on the plastic deformation was investigated.

Free fall safety brakes against accidental cable failure such as in elevators may require friction, wedging action, eddy current, and other effects. An ideal safety brake system should be quick in its deployment with sufficient payload capacity in compact dimensions. In this study, a safety braking system with a quick deployment mechanism is proposed. The mechanism housed in a carrier is suspended by the cable and connected to the payload. At the onset of cable failure, a linkage system is driven by a pre-loaded spring to drive terminal cutting tools tips against the sacrificial braking pads on each side of the vertical track. Experiments showed that large braking force may be achieved by a compact mechanism. Several design issues of linkage deployment, braking force control, and drop dynamics are discussed.

Since the fuel consumption of automobiles increases in proportion to the weight of automobiles, and the emission of exhaust increases in proportion to the amount of fuel consumed, to improve fuel efficiency and reduce exhaust emissions, it is necessary either to develop a highly efficient engine or reduce the weight of the vehicle. In this study, we studied weight reduction using lightweight materials such as aluminum alloys to increase fuel economy. For this purpose, we propose a lightweight design process of the shock tower mounting bracket, which is the largest loaded part among the vehicle parts. The change in strength and dynamic strength was investigated by replacing the existing cast iron material with 320 MPa of aluminum A356 casting material. For strength and dynamic stiffness analysis of the shock tower mounting bracket, the load on the peripheral members was calculated. As a result of the dynamic stiffness analysis, we identified the weak part and calculated that the lifetime of the shock tower mounting bracket is safe for the calculated load conditions. Through this study, we provide a guide for lightweight design and suggest optimal design conditions for development of a vehicle shock tower mounting bracket.

The importance of safety and emergency preparedness of nuclear power plants (NPPs) has been increasingly emphasized since the Fukushima accident. Recently, the Nuclear Robot and Diagnosis Team at Korea Atomic Energy Research Institute (KAERI) initiated research on an unmanned emergency response robotics system. The objective of the research was to provide a practical means that countermeasure the initial accident stages of NPPs. Considering that the robotic systems that tried to mitigate the damage caused by the Fukushima accident did not work adequately, the robotic system to be developed should be tested in the testbed simulating the accident site of NPPs. In this paper, the recent domestic works on a robotic system for the safety of NPP were introduced.

Fluid Catalytic Cracking (FCC) Unit is a large-pressure vessel that converts heavy crude oil, which cannot be distilled, into light crude oil. With the growing interest in renewable energy sources due to environmental regulations, various studies investigating FCC Units are ongoing. The catalytic reactor in FCC Unit is a large structure that generates prolonged high pressure, leading to changes in the properties of the material during operation. Therefore, stress analysis must be conducted based on the application of the actual mechanical properties. In cylindrical thin structures such as the FCC reactor, a tensile test is difficult to perform, warranting the need for Shear Punch (SP) test that uses a small specimen. The properties were utilized in finite element analysis. To determine the boundary and load conditions needed for stress analysis, the operational conditions of the reactor and the conditions for internal pressure of ASME Code regulation were used to evaluate the stress.

Seismic load induces a reverse cyclic load that alternately applies a tensile and a compressive load to a structure. For nuclear piping material, safety is assessed in terms of fracture toughness. However, test results using a quasi-static load can’t guarantee safety if there is a seismic load. In this paper, the fracture toughness of SA312 TP304 stainless steel, which is used as the safety injection pipe of a nuclear power plant, was estimated by using reverse cyclic loads with different ratios of tensile load to compressive load. The test results using a load ratio of -1 (compressive load / tensile load) show that fracture toughness decreases to approximately 10% against a load ratio of zero. These test results show that the reverse cyclic load must be considered in planning for the safety of nuclear power plants under seismic loads.

Most of passive implants belong to medical device are consist of metallic and nonmetallic materials. According to the sort of components, it makes more influence into the human body. In this study, we performed induced-RF (Induced-Radio Frequency) heating evaluation which is part of MRI (Magnetic Resonance Imaging) compatibility and safety test and in-vivo pyrogen test with lumbar stand-alone cage. RF from 3T MRI coil was radiated on medical device, and provided heat nearby stand-alone cage. Thermal change detected areas are distinguished by metallic and nonmetallic part. As followed detection areas, febrility was shown and metallic part was slightly higher than control area, nonmetallic part. Furthermore, stand-alone cage was performed in accordance with in-vivo pyrogen test, and solution injected rabbits had no fever for test period. Through physically and biologically evaluated stand-alone cage, exothemic reaction was observed and we predicted the effect when it would be inserted in patient.