• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.98-102
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• 2012

Increasing the fuel economy has been an inevitable issue for the development of new cars, and one of the important measures to improve the fuel economy is to decrease the vehicle weight. In order to obtain this goal, the researches about lighter, stronger and the well impact absorbing bumper impact beam have been studied without sacrificing bumper safety. In this study, the overall weight reduction possibility of rear bumper impact beam could be examined based on the variation of frontal, offset and corner impact crash capability by substituting a ultra high strength steel material (boron steel ) having tensile strength of 1.5 GPa grade instead of conventional steels. In addition, the section variations (open section, closed section, open section with 5 stays) of the bumper impact beam structure were examined carefully. It could be reached that this analysis could be well established and be contributed for design guide and the optimum design conditions of the automotive rear bumper impact beam development.

• Journal of the Korean Applied Science and Technology
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• v.37 no.2
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• pp.296-302
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• 2020

The purpose of this study was to assess knee joint loading in the target knee during a golf swing compared to loading rates of high impact activities such as cutting and drop landings. Nine healthy competitive golfers completed golf swings with the target foot both straight and externally rotated 30 degrees, as well as drop landings and cutting maneuvers. Motion capture data was collected at 240 Hz and ground reaction force data was collected at 2400 Hz. The frontal and transverse knee moments were examined using repeated measures ANOVA through SPSS. The abduction moments were higher in golf swings as compared to the other high impact activities (p=.010), while the external rotation moments were lower (p=.003). There were no significant differences between externally rotated and neutral golf swings. These results suggest moments applied to the knee during a golf swing are similar to those applied during a high impact activity.

• Journal of Power System Engineering
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• v.13 no.5
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• pp.76-81
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• 2009

The fatalities of pedestrian account for about 21.2% of all fatalities at 2007 year in Korea. To reconstruct exactly the accident, it is important to calculate the throw distance of pedestrian in car to pedestrian accident. The frontal shape of SUV vehicle is dissimilar to passenger car and bus, so the trajectory and throw distance of pedestrian by SUV vehicle is not the same of passenger car and bus. The influencing on it can be classified into the factors of vehicle and pedestrian, and road factor. It was analyzed by PC-CRASH for simulation, and SPSS s/w was used for regression analysis. From the simulation results, the maximum impact energy of multi-body of pedestrian was occurred to that of torso body at the same time. And the throw distance increased with the increasing of impact velocity, and decreased with the increasing of impact offset. Also it decreased with the increasing of velocity of pedestrian at accident, and the throw distance of wet road was longer than that of dry road. Finally, the regression analysis model of SUV(Nissan Pathfinder type)vehicle in car to pedestrian accident was as follows; $$disti_i=-0.87-0.11offseti_i+0.69speed_i-4.27height_i+0.004walk_i+0.63wet_i+{\epsilon}_i$$.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.1
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• pp.1-10
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• 2017

Various offshore structures such as FPSO, FSO, Semi-submersible, TLP and Spar are operated to develop offshore oil and gas fields. Most of the offshore structures shall be operated over 20 years under the harsh environments at sites so that the offshore structures should be designed to endure the harsh environments. In this study, the effect of the impact load (so called slapping load) by the steep waves acting on the FPSO bow is investigated through the model test. For measurement of the impact pressures on the frontal area, a bow-shaped panel was fabricated, and installed the pressure sensors on the bow starboard side of the model FPSO. During the model test campaign, the impact load was investigated using the steep waves with $Hs/{\lambda}$ greater than 1/16 of the representative wave condition. Consequently, it is confirmed through the model test that the impact loads acting on the FPSO bow are significantly increased with the steep waves ($Hs/{\lambda}$ > 1/16) than the representative wave conditions of a maximum significant wave height and a pitch forcing period. Therefore, for safe design of North Sea FPSO, it is necessary to consider the steep waves in addition to the representative wave conditions and to be applied as proper structural load. Also, the effect of random seeds in irregular waves should be considered to build the safe FPSO.

• International Journal of Automotive Technology
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• v.1 no.1
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• pp.35-41
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• 2000

The crashworthiness of vehicles with finite element methods depends on the geometry modeling and the material properties. The vehicle body structures are generally composed of various members such as frames, stamped panels and deep-drawn parts from sheet metals. In order to ensure the impact characteristics of auto-body structures, the dynamic behavior of sheet metals must be examined to provide the appropriate constitutive relation. In this paper, high strain-rate tensile tests have been carried out with a tension type split Hopkinson bar apparatus specially designed for sheet metals. Experimental results from both static and dynamic tests with the tension split Hopkinson bar apparatus are interpolated to construct the Johnson-Cook and a modified Johnson-Cook equation as the constitutive relation, that should be applied to simulation of the dynamic behavior of auto-body structures. Simulation of auto-body structures has been carried out with an elasto-plastic finite element method with explicit time integration. The stress integration scheme with the plastic predictor-elastic corrector method is adopted in order to accurately keep track of the stress-strain relation for the rate-dependent model accurately. The crashworthiness of the structure with quasi-static constitutive relation is compared to the one with the rate-dependent constitutive model. Numerical simulation has been carried out for frontal frames and a hood of an automobile. Deformed shapes and the Impact energy absorption of the structure are investigated with the variation of the strain rate.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.214-222
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• 2002

Computer simulations are widely used to analyze passenger safety in simulated traffic accidents. ATB, Articulated Total Body, is a computer simulation model developed to predict gross human body response to such dynamic environments as vehicle crashes and pilot ejections. ATB, whose code is open, has high flexibility and application capability that users can easily insert defined modules and functions. ATB is, however, inconvenient as it was coded in FORTRAN and it needs a formated input file. Moreover, it takes much time to make input files and to modify coding errors. This study aims to increase user friendliness by adding a preprocessor program, WINATB(WINdows ATB), to the conventional ATB. WINATB, programmed in Visual C＋＋ and OpenGL, uses ATB IV as a dynamic solver. The preprocessor helps users prepare input files through graphic interface and dialog box. An additional postprocessor makes the graphical presentation of simulated results. In these case of the frontal crash, the rear impact and the side impact, the simulation results obtained by WINATB and MADYMO(MAthematical Dynamic Model) are compared to validate the effectiveness of WINAIB.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1686-1694
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• 2003

The foam-filled tube beams can be used for the front rail and firewall structures to absorb impact energy during frontal or side collision of vehicles. In the case of side collision where bending is involved in the crushing mechanism, the foam filler would be effective in maintaining progressive crushing of the thin-walled structures so that much impact energy could be absorbed. In this study, bending behaviors of the closed-cell-aluminum-alloy-foam-filled stainless steel tube were investigated. The various foam-filled specimens including piecewise fillers were prepared and tested. The aluminum-alloy-foam filling offered the significant increase of bending resistance. Their suppression of the inward fold formation at the compression flange as well as the multiple propagating folds led to the increase of load carrying capacity of specimens. Moreover, the piecewise foams would provide the easier way to fill the thin-walled shell structures without the drawback of strength.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.108-113
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• 2005

The damageability and repairability of similar platform type vehicles could be very concerned with design optimization. In all the vehicles crash tested, small size passenger vehicles were weakness in aspect of damageability and repairability. The most critical area appears to be repair cost considering that parts cost is the largest portion of total repair cost segments. Besides repair cost, attaching method of front sidemember and subframe are placed special importance for impact energy absorption and damageability and repairability. So in order to improve damageability and repairability of vehicle structure and body component of the monocoque type passenger vehicles, the end of front side member and front back beam should be designed with optimum level and to supply the end of front side member as a partial condition approx 300mm. The effectiveness of design concept on the 40% offset frontal impact characteristics of the passenger vehicle structure is investigated and summarized.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.129-135
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• 2013

There is not enough absorption space in the side of a vehicle so injuries to a passenger are higher compared to frontal impact injuries. For the protection of the passenger in the event of a side impact, vehicle regulations and new car assessment program(NCAP) are implemented all over the world. However, passive safety such as absorption technology of vehicle body itself is limited due to the narrow space of the side part. At the present time, it is well known that a side airbag including a curtain airbag is the most effective system to protect the passenger during a side impact. In this study, optimum design of the curtain airbag is carried out to reduce Head Injury Criterion(HIC) of the passenger. Based on crashworthiness simulation, an orthogonal array is selected based on the defined design variables, the response surfaces are generated from the orthogonal array and optimization is conducted with the surfaces.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.2
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• pp.88-98
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• 1992

Real automobiles have been utilized to study the occupant behaviors and the response of the structures in the crash environment. Since various parameters are involved in the automobile crashworthiness, a number of experiments must be conducted. The experiments have been contributed to increasing the cost due to the fact that the test is quite expensive. Therefore, computer simulation is adopted to reduce the number of experiments. A few computer programs have been developed specifically to solve the occupant responses in the crash environment. In this research, a software is used to study the occupant dynamic analysis. A modeling of occupant analysis is established for a passenger car and the results are verified through comparisons with real experiments. In the modeling, data are tuned very carefully so that simulated results such as HIC(Head Injury Criterion) and acceleration of each body may approximate to the experimental results. The compared experiment is a barrier test which is carried out by frontal impact. A feedback to the design process is suggested from the result of this research.