• Korean Journal of Soil Science and Fertilizer
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• v.36 no.4
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• pp.193-199
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• 2003

Electrical conductivity (EC) is a major indicator of soil salinity. Measurement of EC in saturation-paste extract of soil (ECe) is a standard way to evaluate soil salinity. However, many of the data on soil salinity have been obtained by measuring the EC of 1:5 soil-water extract (EC1:5) or salt percentage which is calculated from EC1:5 by multiplying a conversion factor. We analyzed 90 soil samples collected from 9 reclaimed tidelands in Korea, and derived relationships between ECe and dilution factors (DF1:5) which can convert EC1:5 to ECe in 2 soil textural groups at 5 salinity levels. Regression equations between ECe and DF1:5 were DF1:5 = 1.3624In(ECe) + 5.1386($r^2=0.37^{***}$) for soils of more than 50% silt content, DF1:5 = 1.9505In(ECe) + 5.3679($r^2=0.66^{***}$) for soils of less than 50% silt content. And the relationship for all soils investigated was DF1:5 = 1.4001In(ECe) + 5.4865($r^2=0.51^{***}$). From the relationships, conversion factors for calculation of ECe from EC1:5 of salt percentage data were estimated for soils of different textures and salinity levels.

• Smart Structures and Systems
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• v.24 no.4
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• pp.427-434
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• 2019

This study investigates the structural integrity of the amphibious tour bus under the rollover condition. The multi-purpose bus called Dual Mode Tour Bus (DMTB) which explores on land and water has been designed on top of a truck platform. Prior to the fabrication of new upper body and sailing equipment of DMTB, computational analysis investigates the rollover protection of the proposed structure including superstructure, wheels, and axles. The Computer-Aided Design (CAD) of the whole vehicle model is meshed and preprocessed under high performance using the Altair HyperMesh to attain the best mesh model suited for finite element analysis (FEA) on the proposed system. Meanwhile, the numerical model is analyzed by employing LS-DYNA to evaluate the superstructure strength. The numerical model includes detail information about the microstructure and considers wheels and axles as rigid bodies but excludes window glasses, seats, and interior parts. Based on the simulation analysis and proper modifications especially on the rear portion of the bus, the local stiffness significantly increased. The vehicle is rotated to the contact point on the ground based on the mathematical method presented in this study to save computational cost. The results show that the proposed method of rollover analysis is highly significant not only in bus rollover tests but in crashworthiness studies for other application. The critical impartments in our suggested dual-purpose bus accepted and passed "Economic Commission for Europe (ECE) R66".

• Composites Research
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• v.21 no.1
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• pp.22-29
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• 2008

This paper presents the evaluation of crashworthiness and rollover characteristics of low-floor bus vehicles made of aluminum honeycomb sandwich composites with glass-fabric epoxy laminate facesheets. Crashworthiness and rollover analysis of low-floor bus was carried out using explicit finite element analysis code LS-DYNA3D with the lapse of time. Material testing was conducted to determine the input parameters for the composite laminate facesheet model, and the effective equivalent damage model for the orthotropic honeycomb core material. The crash conditions of low-floor bus were frontal accident with speed of 60km/h. Rollover analysis were conducted according to the safety rules of European standard (ECE-R66). The results showed that the survival space for driver and passengers was secured against frontal crashworthiness and rollover of low-floor bus. Also, The modified Chang-Chang failure criterion is recommended to predict the failure mode of composite structures for crashworthiness and rollover analysis.

• International Journal of Railway
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• v.6 no.3
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• pp.85-89
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• 2013

The purpose of this paper is investigating the effect and influence rates of utilizing thin walled energy absorption tubes for improving crashworthiness parameter by increasing energy absorption of the body in high speed railcars. In order to find this, a proper profile of available tubes is chosen and added to the structure of selected high speed train in Iranian railway network (Pardis Trainset) and then examined in the scenario of impact with other moving rolling stock. Because of the specific features of LS-DYNA 3D software at collision analysis, the dynamic simulation has been performed in LS-DYNA 3D. The results of the analysis clearly indicate the improvement of train crashworthiness as the energy absorption of structure increases more than 30 percent in comparison with the original body. This strategy delays and reduces the shock to the structure. The verification of the simulation is by using ECE R66 standard.