• Computational Structural Engineering
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• v.10 no.2
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• pp.161-169
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• 1997

It is known that tire plays an important role to the dynamic performances of a vehicle such as noise, vibration, ride and handling. Therefore, force and moment measurements have been a part of the traditional tire engineering process. In this paper, a computational analysis technique has been explored. A FE model is made to simulate inflation, vertical load due to the vehicle weight, and the slow rolling of a radial tire. A rigid surface with Coulomb friction is included in the model to simulate the slow rolling contact. The tire slip during the in-plane motion of the rigid surface is calculated. Results are presented for both lateral and vertical loads, as well as straight ahead free rolling. The calculated and measured tire slips are in good correlation. A Study on slow Rolling Tire for perdiction of tire Forces and Moments.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.355-362
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• 2021

Since coaxial magnetic gears use non-contact power transmission, friction, wear, noise, and heat generated in the power transmission process of existing mechanical gears can be minimized. Currently, research for application to various industries is being actively conducted, but among the characteristics of coaxial magnetic gears, the problem of rapidly decreasing torque density at a high gear ratio was discussed. This paper proposes a direction for multiple gear combination using low gear ratio coaxial magnetic gears with high torque density. In order to confirm the effectiveness of the method, the torque density was compared with a single high gear ratio model, and the combination and design direction of multiple coaxial magnetic gears were shown.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.6
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• pp.1-7
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• 2022

This work investigated the performance improvement of a medium-pressure fixed-displacement-type SPUR gear pump, which is mainly used in the machine tool industry. The 3D CFX analysis and IS technique were applied using ANSYS (commercial FEM code) and compared with experimental results to ensure the reliability of the analysis. In addition, the performance improvement of the pump was obtained using the theoretical volumetric displacement equation, and the gear tooth width was changed. The pressure flow performance curves were compared, and the results were analyzed according to the width of the gear teeth. This is a factor that can cause irregular flow, vibration, and noise inside the gear pump owing to friction between the housing and gear pump.

• Journal of the Korean Society of Safety
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• v.38 no.2
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• pp.36-43
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• 2023

In this study, a four-point bending test was conducted to assess and detect the damage to reinforced concrete structures using the acoustic emission (AE) technique. Based on the crack investigation results, flexural failure was classified into four stages and compared with the characteristic analysis results of AE parameters. The parametric characterization indicated that the activity of the primary AE signal was high in the early stage, and that of the second signal increased after the flexural cracks stabilized. Because the secondary AE signal included noise generated by friction, parameter-based analysis for damage assessment was performed using the primary signal; the secondary signal was used as complement. The activity analyses of the primary and secondary signals effectively classified crack propagation; however, determining the macrocracks and yielding of reinforcing bars had certain limitations. Nevertheless, applying the damage index with cumulative AE energy is a complementary technique for detecting and assessing structure damage that well detects the occurrence of macrocracks.

• Smart Structures and Systems
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• v.29 no.5
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• pp.729-746
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• 2022

In this paper, a nonlinear structural model updating methodology based on the Deep Belief Network (DBN) is proposed. Firstly, the instantaneous parameters of the vibration responses are obtained by the discrete analytical mode decomposition (DAMD) method and the Hilbert transform (HT). The instantaneous parameters are regarded as the independent variables, and the nonlinear model parameters are considered as the dependent variables. Then the DBN is utilized for approximating the nonlinear mapping relationship between them. At last, the instantaneous parameters of the measured vibration responses are fed into the well-trained DBN. Owing to the strong learning and generalization abilities of the DBN, the updated nonlinear model parameters can be directly estimated. Two nonlinear shear-type structure models under two types of excitation and various noise levels are adopted as numerical simulations to validate the effectiveness of the proposed approach. The nonlinear properties of the structure model are simulated via the hysteretic parameters of a Bouc-Wen model and a Giuffré-Menegotto-Pinto model, respectively. Besides, the proposed approach is verified by a three-story shear-type frame with a piezoelectric friction damper (PFD). Simulated and experimental results suggest that the nonlinear model updating approach has high computational efficiency and precision.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.5
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• pp.827-834
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• 2023

In this paper, a slotless outer rotor BLDC motor for a vehicle blower was designed and manufactured to improve the disadvantages of general motors. The proposed motor solves the noise caused by mechanical friction of DC motor during rotation by removing the brush, Also, slotless air-gap windings are used to improve cogging torque by BLDC motor slots. Then, the motor has a structure in which a magnet is attached to the external rotor and rotates simultaneously with the internal rotor, there is no change in magnetic flux. Therefore, it has high efficiency by fundamentally reducing iron loss.

• Journal of Auto-vehicle Safety Association
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• v.16 no.1
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• pp.12-20
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• 2024

Side impact with MDB (moving deformable barrier) is common in side crash test protocols around the globe, most of which are quite similar to that of US NCAP side impact protocol but IIHS side impact protocol is considered to be the most harsh one due to the MDB's weight and impact speed. In this study US NCAP side impact and IIHS side impact test conditions are compared with respect to delta-V (impulse of the test vehicle), roll speed, and yaw speed as well as survival space (the smallest distance between the front driver seat cushion center to B pillar after the test). Error factors (friction between tire and ground, tolerance of vertical and longitudinal position of the MDB with respect to the test vehicle), which are resident in the test protocol is studied with respect to the global vehicle behavior (delta-V, roll, yaw) as well as survival space.

• Composites Research
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• v.34 no.3
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• pp.192-198
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• 2021

Due to enormous market growing of electric vehicles without combustion engine, reducing unwanted BSR (buzz, squeak, and rattle) noise is highly demanded for vehicle quality and performance. Particularly, innerbelt weatherstrips which not only block wind noise, rain, and dust from outside, but also reduce noise and vibration of door glass and vehicle are required to exhibit high damping properties for improved BSR performance of the vehicle. Thermoplastic elastomers (TPEs), which can be recycled and have lighter weight than thermoset elastomers, are receiving much attention for weatherstrip material, but TPEs exhibit low material damping and compression set causing frictional noise and vibration between the door glass and the weatherstrip. In this study, high damping EPDM (ethylene-propylene-diene monomer)/PP (polypropylene) thermoplastic vulcanizates (TPV) were investigated by varying EPDM/PP ratio and ENB (ethylidene norbornene) fraction in EPDM. Viscoelastic properties of TPV materials were characterized by assuming that the material damping is directly related to the viscoelasticity. The optimum material damping factor (tanδ peak 0.611) was achieved with low PP ratio (14 wt%) and high ENB fraction (8.9 wt%), which was increased by 140% compared to the reference (tanδ 0.254). The improved damping is believed due to high fraction of flexible EPDM chains and higher interfacial slippage area of EPDM particles generated by increasing ENB fraction in EPDM. The stick-slip test was conducted to characterize frictional noise and vibration of the TPV weatherstrip. With improved TPV material damping, the acceleration peak of frictional vibration decreased by about 57.9%. This finding can not only improve BSR performance of electric vehicles by designing material damping of weatherstrips but also contribute to various structural applications such as urban air mobility or aircrafts, which require lightweight and high damping properties.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.1-8
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• 2021

This study developed low-cost and high-efficiency pavement condition monitoring technology to produce the key information required for pavement management. A noise and artificial intelligence-based monitoring system was devised to compensate for the shortcomings of existing high-end equipment that relies on visual information and high-end sensors. From idea establishment to system development, functional definition, information flow, architecture design, and finally, on-site field evaluations were carried out. As a result, confidence in the high level of artificial intelligence evaluation was secured. In addition, hardware and software elements and well-organized guidelines on system utilization were developed. The on-site evaluation process confirmed that non-experts could easily and quickly investigate and visualized the data. The evaluation results could support the management works of road managers. Furthermore, it could improve the completeness of the technologies, such as prior discriminating techniques for external conditions that are not considered in AI learning, system simplification, and variable speed response techniques. This paper presents a new paradigm for pavement monitoring technology that has lasted since the 1960s.

• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.45-54
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• 2015

In the case of railway facilities in cities such as a railway station or a bridge, the significance of design for reducing vibration and noise is getting more significant. The vibration control solution is in need especially for an elevated railway station to block vibration of a train and secondary noise effectively. Even though a vertical vibration isolation device is able to be applied effectively to railway facilities such as elevated railway stations which transfer vibration directly from a train to a structure, the development of the vertical device is much slower than a horizontal vibration isolation device. In this paper, a vibration isolation device using wedge type friction material which is currently developing to reduce train-induced vibration effectively is introduced and test results for verification of dynamic performance is also presented. The vibration test on a concrete structure equipped with the developed vibration isolation device is conducted through which the isolation performance and dynamic properties are verified and needs for improving the performance of the device is identified.