• Journal of Auto-vehicle Safety Association
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• v.14 no.3
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• pp.60-64
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• 2022

In the automotive industry, the development of automobiles to meet safety requirements is becoming increasingly complex. This is because quality evaluation agencies in each country are continually strengthening new safety standards for vehicles. Among these various requirements, collision safety must be satisfied by controlling airbags, seat belts, etc., and can be defined as post-crash safety. Apart from this safety system, the Advanced Driver Assistance Systems (ADAS) use advanced detection sensors, GPS, communication, and video equipment to detect the hazard and notify driver before the collision. However, research to improve passenger safety in case of an accident by using the sensor of active safety represented by ADAS in the existing passive safety is limited to the level that utilizes the sudden braking level of the FCA (Forward Collision-avoidance Assist) system. Therefore, this study aims to develop logic that can improve passenger protection in case of an accident by using ADAS information and driving information secured before a collision. The proposed logic was constructed based on LSTM deep learning techniques and trained using crash test data.

• Journal of Auto-vehicle Safety Association
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• v.4 no.2
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• pp.37-43
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• 2012

The purpose of this research is to obtain and analyze dynamic responses from human volunteers for the development of the human-like mechanical or mathematical model for Korean males in automotive rear collisions. This paper focused on the introduction to a low-speed rear impact sled test involving Korean male subjects, and the accumulation of the motion of head and neck. A total of 50 dynamic rear impact sled tests were performed with 50 human volunteers, who are 30-50 year-old males. Each subject can be involved in only one case to prevent any injury in which he was exposed to the impulse that was equivalent to a low-speed rear-end collision of cars at 5-8 km/h for change of velocity, so called, ${\Delta}V$. All subjects were examined by an orthopedist to qualify for the test through the medical check-up of their necks and low backs prior to the test. The impact device is the pendulum type, tuned to simulate the crash pulse of a real vehicle. All motions and impulses were captured and measured by motion capture systems and pressure sensors on the seat. Dynamic responses of head and T1 were analyzed in two cases(5 km/h, 8 km/h) to compare with the results in the previous studies. After the experiments, human subjects were examined to check up any change in the post medical analysis. As a result, there was no change in MRI and no injury reported. Six subjects experienced a minor stiffness on their back for no more than 2 days and got back to normal without any medical treatment.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.64-64
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• 2009

The use of ultra high strength steels (UTSS) is a natural result with increasing the demands for the lightweight materials and developing an innovative steel technology. Recently it has been used a 1500MPa grade hot stamping steel as automobile bodies, reinforcement parts, and seat frame parts in the automotive industry. It is a quenchenable steel manufactured by hot stamping process. It is well known that UTSS welding has softening in the heat affected zone(HAZ). Because welding is a sort of process applying heat, it should change the heat treated features and degrade the strength. This study was performed to investigate the influence of the heat input on the softening of the HAZ in the GMAW process. Each experiment was compared with that in the conditions having a different current and voltage at a same heat input. In order to analysis characteristics of the HAZ, optical microscope was used to observe microstructure and vickers hardness tests were carried out across the welds. Applying low heat input means a fast cooling rate. It leads to high hardness in the HAZ. It is found that characteristics of the HAZ are determined by microstructure obtained by different cooling rate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1623-1630
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• 2010

In this study, effective forming methods for reducing the roll-over of a sector tooth, which is a main component of an automotive seat recliner, are proposed. Due to the large amount of roll-over, accurate contact between the inner gear of a sector tooth and the outer gear of a pawl tooth cannot be normally achieved; thus sensitivity and safety for the passengers decrease. To overcome the aforementioned drawback, we investigated the effect of flowcontrol forming methods involving local embossing die, coining punch, and VIC (Variable Inverse Clearance) on the roll-over depth by FE-analysis and an experiment. The results of a fine-blanking experiment for verifying the proposed methods showed that VIC type is decidedly superior from the aspects of reduction of roll-over and tool strength of the sector tooth.

• Journal of the Korean Institute of Gas
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• v.25 no.5
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• pp.37-51
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• 2021

The pressure drop phenomenon that occurs when the same flow rate is supplied to the gas regulator was analyzed. The regulator moves the position of the piston through the interaction of the force acting on the upper and lower parts of the piston and the spring tension to release the pressure of a specific range in a specific environment as constant pressure, thereby maintaining the pressure. The flow characteristics and pressure control process of the regulator were investigated through a numerical analysis technique as the volume of the fluid inside the regulator changed. As the gap between the piston and the piston seat decreased, the pressure drop increased and the flow velocity increased. It was verified through numerical analysis that the piston was positioned at 0.12mm under the same conditions as the pressure-flow test (inlet pressure 3MPa, outlet pressure 0.8MPa, flow rate 70kg/h).

• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.396-403
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• 2018

In this paper, a high-performance and low-noise centrifugal fan is developed for cooling automotive seats which provide a driver with pleasant driving environment. First, the flow characteristics of the existing fan unit was analyzed using a fan performance tester and CFD (Computational Fluid Dynamics) simulations. The analysis of the predicted flow field indicated vortex flow near the tip of fan hub and stagnation flow on the top of fan hub. Two design points are devised to reduce the vortex flow and the stagnation flow observed in the existing fan unit. First, the cut-off clearance which is the minimum distance between the fan blade and the fan housing is increased to reduce the vortex strength and, as a result, to reduce the overall sound pressure level. Second, the hub shape is more modified to eliminate the stagnation flow. The validity of proposed design is confirmed through the numerical analysis. Finally, a prototype is manufactured with a basis on the numerical analysis result and its improved flow and noise performances are confirmed through the P-Q curves measured by using the Fan Tester and the SPL (Sound Pressure Level) levels measured in the anechoic chamber.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.36-42
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• 2021

With recent developments in the Fourth Industrial Revolution, the manufacturing industry has changed rapidly. Through key aspects of Fourth Industrial Revolution super-connections and super-intelligence, machine learning will be able to make fault predictions during the foam-making process. Polyol and isocyanate are components in polyurethane foam. There has been a lot of research that could affect the characteristics of the products, depending on the specific mixture ratio and temperature. Based on these characteristics, this study collects data from each factor during the foam-making process and applies them to machine learning in order to predict faults. The algorithms used in machine learning are the decision tree, kNN, and an ensemble algorithm, and these algorithms learn from 5,147 cases. Based on 1,000 pieces of data for validation, the learning results show up to 98.5% accuracy using the ensemble algorithm. Therefore, the results confirm the faults of currently produced parts by collecting real-time data from each factor during the foam-making process. Furthermore, control of each of the factors may improve the fault rate.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.2
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• pp.427-435
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• 2017

Most of the domestic city buses are equipped with the pressure vessels subjected to internal pressure applied by compressed natural gas. Pressure vessels subjected to internal pressure are used in various forms and purposes. Fuel is explosive and has flammable high pressure. The damage of the pressure vessel causes many property damage and loss of life. Safe design for pressure vessel is always necessary. Due to these reasons, many studies using finite element analysis have been conducted. In this paper, the stresses of cylindrical vessel and spherical dome were analyzed using ANSYS, a finite element analysis software. In order to verify the validity of the analysis, a model with a perfectly spherical shape of the dome was designed and observed. Based on the ASME standard in used, stress distribution was also analyzed for models designed with compressed natural gas(CNG). The FEM analysis software agreed with the theory when the dome shape was perfectly spherical. The model designed based on the ASME specification theory, stress concentration occurred in the knuckle part.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.2
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• pp.437-444
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• 2017

Stress concentrations around discontinuities, such as a hole in cross section of a structural member, have great importance because the most materials failure around the region may be occurred. Stress on the point applied by concentrated load reaches much larger value than the average stress in structural member. In this paper, stress analysis was performed for the plate with a partial through-hole to find the difference of the principal stress distribution. The difference between maximum principal stress and minimum principal stress in photoelasticity is equal to the value obtained by multiplying the isochromatic fringe order by the fringe constant of the material divided by the distance through which the light passes, that is, the thickness of the specimen. Since the difference of principal stress is proportional to the photoelastic fringe order, the distribution of the principal stress difference by the finite element analysis can be compared with the photoelasticity experimental result. ANSYS Workbench, that is the finite element software, is used to compute the differences of principal stresses at the specific points on the measured lines. The computation values obtained by ANSYS are compared with the experimental measurements by photoelasticity, and two results are comparable to each other. In addition, the stress concentration factor is obtained using the stress distribution analyzed from the variation of hole depth. Stress concentration factor is increasing, as the depth of hole increase.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.3
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• pp.411-419
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• 2017

Stress concentration is one of the causes of the damage due to the large stress than the mean stress acting on the bar. This paper presents the results for stress of a stepped bar with a hole under torsional loading. The analysis for stress concentration and shearing stress was done by ANSYS Workbench which is a commercial finite element analysis software. The analysis results on fillet and hole are increased as the distance between them are become close. In addition, the distribution of the maximum equivalent stress developed in the fillet and hole in the outside range of the specific distance L (-100 mm ~ 300 mm) was almost constant in the models used in the analysis. On the other hand, the distribution of the maximum equivalent stress developed in the fillet and hole in the inside range of the specific distance L (-100 mm ~ 300 mm) was rapidly increasing and decreasing the change in the models used in the analysis. In addition, it was also possible to identify the location where the differences between equivalent stresses of hole and fillet occurred within a specific distance L (-100 mm ~ 300 mm). The analysis results of paper can used when selecting a hole location in a stepped bar under torsional loading.