• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.5 s.98
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• pp.604-611
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• 2005

The relationship between floor impact sound and vibration has been studied by field measurements, and the vibration modal characteristics have been analyzed. Vibration levels impacted by a standard heavy-weight impact source have been predicted according to the main design parameters using finite element method. Experimental results show that the dominant frequencies of the heavy impact sounds range below 100 Hz and that they are coincident with natural frequencies of the concrete slab. In addition, simple 2-dimensional finite element models are proposed to substitute 2 types of 3-dimensional models of complicated floor structural slabs those by The analytical result shows that the natural frequencies from first to fifth mode well correspond to those by experiments with an error of less than $12\%$, and acceleration peak value iscoincident with an error of less than $2\%$. Using the finite element model. vibration levels areestimated according to the design Parameters, slab thickness, compressive strength, and as a result, the thickness is revealed as effective to increase natural frequencies by $20\~30\%$ and to reduce the vibration level by 3$\~$4 dB per 30 mm of extra thickness.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.2
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• pp.77-93
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• 1999

The twin aims of the paper are to investigate the collapse strength characteristics of ship plating subject to impact pressure loads and to develop a simple structural design formula considering impact load effects. The general purpose nonlinear finite element program STARDYNE together with existing experimental results is used to investigate the collapse behavior of plating under impact pressure loads. The rigid plastic theory taking into account large deflection effects is applied to the development of the design formulation. In the theoretical method, the collapse strength formulation for plating subject to hydrostatic pressure is first derived using the rigid plastic theory. By including the strain rate erects in the formulation it can be applied to impact pressure problems. As illustrative examples, the collapse behavior of steel unstiffened plates and aluminum alloy stiffened panels subject to impact pressure loads is analyzed.

• Design & Manufacturing
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• v.10 no.2
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• pp.24-28
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• 2016

In this study, relevant to impact extrusion process of the rectangular batter case for electric vehicles, numerical and experimental analyses were conducted to reduce the earring defects induced in the unevenness of metal flow. Since the earring is caused by the non-uniform metal flow induced in the friction and aspect ratio in the bottom section. As a way to reduce the earring, variable land die concept was applied. In order to analyze numerically the complex metal flow by using commercial finite element package, DEFORM 3D, impact extrusion process was simplified in upsetting mode at bottom section and extrusion mode at land section. The impact extrusion experiments were conducted to verify the assessment of process parameter for impact extrusion. As results, variable land die which has longer longitudinal section makes reduce earring defects. In addition, it was confirmed that the effect that slug shape like dog-bone also can reduce the earring. This study is expected to be able to present the useful design guidelines for manufacturing the battery case.

• The Journal of Information Systems
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• v.30 no.3
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• pp.137-158
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• 2021

Purpose This study aims to investigate which factors have impact on the acceptance intention of new electronic ID. For the empirical analysis, this study utilized PLS-SEM after collecting 385 survey data, and analyzed relations between each factors. Design/methodology/approach This study made a design of the research model by integrating the factors deducted from the Unified Theory of Acceptance and Use of Technology with the factors deducted from the Risk Factors. Findings The results are as follow; First, of the UTAUT factors, Performance Expectancy, Effort Expectancy and Social Influence and has positive impact on Acceptance Intention, but Facilitating Conditions doesn't have meaningful impact on Acceptance Intention. Second, of the Risk factors, Innovation Resistance has negative impact on Acceptance Intention, but Perceived Risk dose not have meaningful impact on Acceptance Intention. Finally, regulatory effect of the Promotion Focus, Prevention Focus and Gender has regulatory impact to Acceptance intention. It is expected that the implications of this study enables government effectively to offer new electronic ID.

• Carbon letters
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• v.16 no.2
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• pp.107-115
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• 2015

Impact damages induced by a low-velocity impact load on carbon fiber reinforced polymer (CFRP) composite plates fabricated with various stacking sequences were studied experimentally. The impact responses of the CFRP composite plates were significantly affected by the laminate stacking sequences. Three types of specimens, specifically quasi-isotropic, unidirectional, and cross-ply, were tested by a constant impact carrying the same impact energy level. An impact load of 3.44 kg, corresponding to 23.62 J, was applied to the center of each plate supported at the boundaries. The unidirectional composite plate showed the worst impact resistance and broke completely into two parts; this was followed by the quasi-isotropic lay-up plate that was perforated by the impact. The cross-ply composite plate exhibited the best resistance to the low-velocity impact load; in this case, the impactor bounced back. Impact parameters such as the peak impact force and absorbed energy were evaluated and compared for the impact resistant characterization of the composites made by different stacking sequences.

• Journal of Mechanical Science and Technology
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• v.19 no.spc1
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• pp.422-428
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• 2005

In this paper, the contact force between two colliding bodies is modeled by using Hertz's force-displacement law and nonlinear damping function. In order to verify the appropriateness of the proposed contact force model, the drop type impact test is carried out for different impact velocities and different materials of the impacting body, such as rubber, plastic and steel. In the drop type impact experiment, six photo interrupters in series close to the collision location are installed to measure the velocity before impact more accurately. The characteristics of contact force model are investigated through experiments. The parameters of the contact force model are estimated using the optimization technique. Finally the estimated parameters are used to predict the impact force between two colliding bodies in opening action of the magnetic contactor, a kind of switch mechanism for switching electric circuits.

• The Journal of the Acoustical Society of Korea
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• v.15 no.1E
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• pp.5-19
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• 1996

This paper proposes a loose part monitoring system (LPMS) design with a signal processing method based on fuzzy logic. Considering fuzzy characteristics of metallic impact waveform due to not only interferences from various types of noises in an operating nuclear power plant but also complex wave propagation paths within a monitored mechanical structure, the proposed LPMS design incorporates the comprehensive relation among impact signal features in the fuzzy rule bases for the purposes of alarm discrimination and impact diagnosis improvement. The impact signal features for the fuzzy rule bases include the rising time, the falling time, and the peak voltage values of the impact signal envelopes. Fuzzy inference results based on the fuzzy membership values of these impact signal features determine the confidence level data for each signal feature. The total integrated confidence level data is used for alarm discrimination and impact diagnosis purposes. Through the perpormance test of the proposed LPMS with mock-up structures and instrumentation facility, test results show that the system is effective in diagnosis of the loose part impact event(i.e., the evaluation of possible impacted area and degree of impact magnitude) as well as in suppressing false alarm generation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.791-794
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• 2002

On this study, the dynamic response of vibration absorber was operated by finite element analysis and this paper proposed the optimum value of spring constant and damping coefficient for three types of impact absorber. Also the reaction farce of piston which is the objective function was proposed by the optimum design and the model which has the optimum value among the reaction forces was shown.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2001.10a
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• pp.242-245
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• 2001

This study is aimed to design a priority setting algorithm necessary for evaluating and selecting interdependent R&D planning system alternatives. In case that the relationship of technology alternatives is interdependent, a relative importance as occurrence or nonoccurrence of the technology alternatives viewed from the future time varies. So, we are subject to design the evaluation process considering a cross- impact of future technology alternatives. Thus, we apply the cross impact analysis (CIA) model to consider the cross-impact among interdependent system alternatives. Also, the analytic hierarchy process(AHP) model is applied to determine the priority of alternatives by taking the pair-wise comparison among factors.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.173-180
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• 2000

European side impact analysis of an electric vehicle was done using robust design. Locations and section properties of some of the vehicle structure components which influence the european side impact characteristics were chosen as the main factors for the robust design. Eight factors were considered for the analysis: one with two level and seven with three level combinations comprising the L18(21$\times$37) orthogonal array. It is shown that the sensitivities of the factors and the best combination of the factors can be obtained, and that the location of the main components were as much sensitive as the section properties of those. Also it is shown that the interactions were existed between some factors.