• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.280-285
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• 2012

The 1st assessment (performance test) was applied to assure the floor impact sound performance for developing the dry double- floor with the change of rubber hardness of the upper panel's support and the ceiling structure of the sub-floor. Depends on the change of the rubber hardness in substructure, the heavy-weight sound impact value is improved up to 3 dB, and the light-weight sound impact value is moved up to 21 dB, comparing with the bare-slab. Also, the improved value for the floor impact sound conjugating with the sub-floor's ceiling was 5dB. Based on this result, the 2nd assessment (performance test) was made the state that the rubber hardness of the sub-floor support was ranged between 50 and 70 for considering the stability of walking patients. In addition to this process, the assessment was carried out with a variety of ceiling structure applied to the dry doublefloor structure with the air flow system on the sub-floor's ceiling. The result for the 2nd assessment proved that TYPE-11 had the better sound reduction performance in the heavy-weight impact sound test than other types, and also for the light-weight impact sound TYPE-11 had the 29 dB sound reduction performance overall. Henceforth, based on the result the research for the sound reduction performance from the floor impact sound shall be ongoing process as well as the development of a double-dry floor and a sound reduction ceiling to suitable on the field.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.8
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• pp.41-46
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• 2006

The capability for reconstructing impact forces of an aircraft wing using impact response functions and regularization methods were examined. The impact response function which expresses the relation between the structure response and the impact force was derived using the information on mass and stiffness data of a finite element model for the wing. Iterative Tikhonov regularization method and generalized singular value decomposition method were used to inverse the impact response function that was generally ill-posed. For the numerical verification, a fighter aircraft wing was used. Strain and deflection histories obtained from finite element analysis were compared with the results calculated using impact response functions. And the impact forces were reconstructed with the strain histories obtained from finite element analysis. The numerical verification results showed that this method can be used to monitor impact forces on aircraft structures.

• Elastomers and Composites
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• v.49 no.4
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• pp.284-292
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• 2014

Polymer has low mechanical strength than metal. In particular, the impact strength is very weak. Impact modifier reinforced polymers are frequently used. Impact strength of reinforced polymer is changed according to content and distribution of impact modifier. In this study, izod impact test has been simulated to analyze the mechanism of impact modifier reinforced Nylon 6. Computational results were compared for numbers and distributions of impact modifier. As the total volume of rubber particles decreased, the stress at the notch increased for the simulation model that the volume decreases as particle number increases. As the surface area of particle sphere increased, the stress and difference of principle stress increased for the simulation model that the total surface increases as particle number increases.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.175-186
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• 2010

When a rigid post is exposed to traffic, it is hazardous not only to head-on impacts but also to side impacts. Clip-type slip base is an effective measure to reduce the severity of head-on impacts and side impacts as well because of its multi-directional release mechanism. Side impact tests were conducted and the results were analysed to demonstrate the hazardousness of a rigid post to a side impact and the crash worthiness of a post having clip-type slip base. For that, side impact test standard was made adapting the NCHRP Report 350, and 820kg-50km/h side impact tests were made for posts of D101.6mm(t=4.2mm) with and without slip base. Additionally, 35km/h side impact to the same post with slip base was conducted to check whether the clip-type slip base release mechanism works properly to the low impact speed. The tests revealed that the rigidly connected post was very hazardous to side impact while the post with the clip-type slip base reduced the impact severity tremendously.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.787-793
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• 2002

In this study, a bar impact test of low velocity was carried out to gain an insight into the damage mechanism and sequence induced in alumina plates(AD 85 and AD 90) under impact conditions. An experimental setup utilizing an instrumented long bar impact was devised, that can measure directly the impact force applied to the specimen and supply a compressive contact pressure to the specimen. During the bar impact testing, the influences of the contact pressure applied along the impact direction to the specimen on the fracture behavior were investigated. The measured impact force profiles explained well the damage behavior induced in alumina plates. The higher contact pressure to the specimen led to the less damage due to the suppression of radial cracks due to the increase in the apparent flexural stiffness of plate. It had produced the change of damage pattern developed in the specimen; from the radial cracks to the local contact stress dominant damage. It would contribute to the improvement of the ballistic property in ceramic plates. The observed results showed the following sequence in damage developed: The development of cone crack at impact region, the formation of radial cracks from the rear surface of plate depending on the plate thickness, the occurrence of crushing within the cone envelope and the fragmentation.

• Architectural research
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• v.21 no.2
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• pp.41-48
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• 2019

The purpose of this study is to research and development of 'Korea B(Benefit)-impact Model' for Sustainable Development. A concept evaluation model is 'B(Benefit)-impact model' in U.S.A. We use the results of surveys that examined the importance of social value issues to stakeholders in Korea to implement the benefit-impact model in Korea. In particular, in this paper, we use the KSI(Korean Sustainability Index) survey data conducted by the Korea Standards Association to evaluate the social value of the construction industry for representative stakeholders in the construction industry. The social value pool and the activity indicator pool used for the survey are created based on relevant International Standards; ISO 26000, ISO 14001, ISO 37001. As a result, Korea B-impact model for construction industry included the following five core social value issues; Strengthen transparency of corporate management, Ensure fair employment and employment relations, Efforts to prevent corruption, Conduct fair competition, Efforts to prevent environmental pollution. In addition, the US B-impact model has three limitations. First, it is unclear whether the key indicators have been derived while considering all issues of social value. Second, US B-impact model indicators are developed by the social responsibility experts, so it is necessary to review by stakeholders in each industry. Finally, it would be more effective for companies to use the B-impact model index as a more detailed activity indicator. When developing a Korea B-impact model, the following methods are used to supplement it. First, we reviewed all social value issues using international standards. Secondly, we used the KSI(Korean Sustainability index) survey results to derive the importance of the social value issue of construction industry in Korea. Finally, we have clearly matched the activity indicators by social value core issues based on the GRI Standard so that companies can actually use the Korea B-impact model for the construction sector. The detailed development stages and results of this study are as follows;.

• Journal of Aerospace System Engineering
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• v.13 no.2
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• pp.19-25
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• 2019

To detect the impact location of a structure, the authors' group conducted a study on piezoelectric paint sensor. The piezoelectric paint sensors are used for impact detection due to their inherent characteristics: sensitivity to high-frequency signal and impact. Additionally, the paint sensor can be applied on curved and complex structures where ceramic sensor would not be applicable. Moreover it is a self-powered sensor therefore no need for an external power source. For impact localization, mosaic pattern electrodes were coated on the specimen and the impact signal obtained from any part of the electrode where the impact occurred. If we more precise impact localization is required, the electrodes should be divided into more parts and impact data acquisition conducted in all the points of the electrode. In this paper, we developed a light, cheap and simple multi-channel data acquisition system to aid in data gathering. In total four channels data acquisition have been tested using the ARM Cortex-M3.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.6
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• pp.563-569
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• 2020

Presenting the impact of meteorological disasters departs from the traditional weather forecasting approach for meteorological phenomena. It is important to provide impact forecasts so that precautions against disruption and damage can be taken. Countries such as the United States, the U.K., and France already conduct impact forecasting for heavy rain, heavy snow, and cold weather. This study improves and applies forecasts of the impact of heavy rain among various weather phenomena in accordance with domestic conditions. A total of 33 impact factors for heavy rain were constructed per 1 km grids, and four impact levels (minimal, minor, significant, and severe) were calculated using standard normal distribution. Estimated criteria were used as indicators to estimate heavy rain risk impacts for 6 categories (residential, commercial, utility, community, agriculture, and transport) centered on people, facilities, and traffic.

• Journal of Aerospace System Engineering
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• v.17 no.4
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• pp.43-57
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• 2023

The hypervelocity impact simulations of space objects and structures are performed using LS-DYNA. Space objects with spherical, conical, and hollow cylindrical shapes are modeled using the Smoothed Particle Hydrodynamics (SPH). The direct and indirect impact zones of a space structure are modeled using the SPH and finite element methods, respectively. The Johnson-Cook material model and Mie-Grüneisen Equation of State are used to represent the nonlinear behavior of metallic materials in hypervelocity impact. In the hypervelocity impact simulations, various impact conditions are considered, such as the shape of the space object, the thickness of the space structure, the impact angle, and the impact velocity. The shapes of debris clouds are quantitatively classified based on the geometric parameters. Conical space objects provide the worst debris clouds for all impact conditions.

• Composites Research
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• v.20 no.4
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• pp.42-50
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• 2007

This paper describes the results of experiments and numerical simulation studies on the low-velocity impact damage of two different sandwich composite panels for application to bodyshell and floor structure of the BIMODAL tram vehicle. Square test samples of 100mm sides were subjected to low-velocity impact loading using an instrumented testing machine at four impact energy levels. Part of this work presented is focused on the finite element analysis of low-velocity impact response onto a sandwich composite panels. It is based on the application of explicit finite element (FE) analysis codes LS-DYNA 3D to study the impact response of sandwich structures under low-velocity impact conditions. Material testing was conducted to determine the input parameters for the metallic and composite material model, and the effective equivalent damage model for the orthotropic honeycomb materials. Numerical and experimental results showed a good agreement for damage area and the depth of indentation of sandwich composite panels created by the impact loading.