• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.2
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• pp.61-70
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• 2013

An application of the EQS (Eradi Quake System) bearings to a short period building structure and the structure earthquake responses according to the design parameters of the EQS are studied by the ICT Center case study. The features of the EQS application to seismic isolated building structures are investigated, and the design procedure to determine the yield load and the secondary stiffness of the EQS is also studied. A computational analysis is performed to confirm the applicability of the EQS to the building structure and the earthquake responses according to the design parameters. The ICT Center in Indonesia is adopted as an application case of the EQS. The application of the EQS is found to extend the fundamental period of the ICT Center. Three types of EQS with different yield loads and secondary stiffness are designed and applied in the earthquake response analyses. The analysis results show the response of the structure with respect to the design parameters and which type of EQS is suitable for the ICT Center.

• Structural Engineering and Mechanics
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• v.76 no.3
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• pp.311-324
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• 2020

Until now, a comparative study on fully and partially-connected steel shear walls leading to enhancing strength and stiffness reduction of partially-connected steel plate shear wall structures has not been reported. In this paper a number of 4-story and 8-story steel plate shear walls, are considered with three different connection details of infill plate to surrounding frame. The specimens are modeled using nonlinear finite element method verified excellently with the experimental results and analyzed under monotonic loading. A comparison between initial stiffness and shear strength of models as well as percentage of shear force by model boundary frame and infill plate are performed. Moreover, a comparison between energy dissipation, ductility factor and distribution of Von-Mises stresses of models are presented. According to the results, the initial stiffness, shear resistance, energy dissipation and ductility of the models with beam-only connected infill plates (SSW-BO) is found to be about 53%, 12%, 15% and 48% on average smaller than those of models with fully-connected infill plates (SPSW), respectively. However, performance characteristics of semi-supported steel shear walls (SSSW) containing secondary columns by simultaneously decreasing boundary frame strength and increasing thickness of infill plates are comparable to those of SPSWs. Results show that by using secondary columns as well as increasing thickness of infill plates, the stress demands on boundary frame decreases substantially by as much as 35%. A significant increase in infill plate share on shear capacity by as much as 95% and 72% progress for the 4-story SSW-BO and 8-story SSSW8, respectively, as compared with non-strengthened counterparts. A similar trend is achieved by strengthening secondary columns of 4-story SSSW leading to an increase of 50% in shear force contribution of infill plate.

• Journal of the Korean Society for Railway
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• v.2 no.2
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• pp.6-12
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• 1999

In this study, the most important suspension characteristics of railway vehicle, such as primary and secondary stiffness, are optimized to maximize ride qualify. Critical speed, secondary suspension stroke oil tangent track and derailment coefficient on the maximum curvature, are selected as the performance constraints. Piecewise linear curving model is used to evaluate derailment coefficient where it is assumed that wheel/rail contacts occurs at tread or at idealized flange. The combined design procedure is used to optimize above design variables at the same time.

• 연구논문집
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• s.27
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• pp.35-45
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• 1997

The dynamic design process for the articulated bogie of light rail vehicle(LRV) was studied to design a primary and secondary suspension elements. Suspension stiffness and damping is selected on the basis of the ride quality and suspension stroke trade-off. LRV was modeled as a 2 d.o.f linear system for the design of vertical suspension characteristics and a 4 d.o.f linear system for the design of lateral suspension characteristics. FRA's class-4-track irregularity was used for the exciting disturbance on track. The optimum value of primary and secondary suspension characteristics was determined using this design process.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.1
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• pp.53-65
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• 1992

For improving the performance of maglev systems with a combined lift and guidance, it is suggested that the multivariable control systems and a secondary suspension should be added. The former is required to reject both track irregularities in vertical disturbances and wind gusts in lateral disturbances, and the latter to guarantee passengers against an unsatisfied criteria in ride quality. In this paper, bond graph model for the study of nonlinear dynamics of maglev systems with a combined lift and guidance is presented briefly. And, the secondary suspension is analyzed to understand the role of stiffness and damping factors in passive devices. Finally, LQG/LTR mulitivariable control systems are designed for the overall maglev systems with and without secondary suspension, and then the system performances in these two cases are evaluated.

• 연구논문집
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• s.22
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• pp.39-46
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• 1992

A dynamic design process was proposed for the design of the secondary suspension characteristics of a magnetically levitated vehicle(MAGLEV). It is based on a ride quality-secondary stroke trade-off. For the vertical vibration analysis, a magnetically levitated vehicle was simplified as 2 d.o.f. linear model, and FRA's class-6-track irregularities were considered as exciting disturbances. The optimum value of airspring stiffness and damping coefficient for the secondary suspension of a prototype MAGLEV was determined using this proposed design process.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.202-206
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• 2005

Most of studies on the open section composite beams are confined to the thin composite beams. There are some works focused on the thick composite beams but they are limited only to closed section beams. Therefore, it is required to develop an appropriate model to analyze the thick open section composite beams. In this study, the cantilever beams of two specific lay-up configurations are considered which are the circumferentially asymmetric stiffness (CAS) and circumferentially uniform stiffness (CUS) beams. Under the torsional loading, loading induced deformations are obtained for the thick beams using the suggested model. The model includes coupled stiffness and secondary warping effects. The results are compared with those obtained using thin beam model to observe the thickness effects. Those results are also compared with the finite element analysis results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.89-92
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• 2012

Marine diesel generator(D/G) set which is supported with resilient mounts for vibration isolation has been experienced the resonance problem by the main engine or propeller excitations and rigid body modes. Then the avoidance of resonance is difficult because the several excitations and 6 rigid body modes have to be considered simultaneously. In this paper, stiffness adjustable mounts was developed and proposed to control the natural frequencies of installed D/G set. Operating concept of the mount is that the total stiffness of mount can be changed according to the engagement of secondary rubber element in addition to primary one. The performance of mount was verified with the test rig and actual experiment in D/G set.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.84-90
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• 2018

In constructing the multi-body dynamics model to analyze the behavior of the railway vehicle, it is very important to understand the properties of the suspension elements that constitute the suspension system. Among them, coil springs, which are mainly used in primary and secondary suspension systems, clearly show the axial stiffness in the drawings, but the lateral properties of the coil springs are not specified clearly, making it difficult to construct a dynamic analysis model. Therefore, in this paper, the model for analyzing the lateral stiffness of the coil spring is examined. A finite element method was applied to analyze the lateral stiffness of the coil spring and numerical analysis was performed by applying the coil spring lateral stiffness analysis model proposed by Krettek and Sobczak. And the test to analyze the lateral stiffness of coil spring was conducted. As a result of comparing with the test results, it was found that the results obtained by applying the lateral stiffness analysis model of Krettek and Sobczak and correcting the correction coefficient are similar to those of the test results.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1708-1713
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• 2003

The acceptance test of KTX has been performed in Korea. During the test, lateral vibration of carbody over the accepted value called swat was found. KTX has 20 car trainsed formation whose trailer cars are linked by articulate bogies. So this study is performed to see the effects of long trainsed formation on vehicle dynamics and the train stability by 20 car vehicle model. Firstly the reliable vehicle model which shows well the tendencies appeared in the tests on the high speed test line is required to find the cause of lateral vibration and the countermeasure. Vehicle model was made for the analysis with VAMPIRE. The analysis results show that secondary air spring lateral stiffness is the most significant parameter to cause carbody lateral vibration. Mode analysis results show that he least damped mode shape is similar to the vibration pattern shown in the tests that the amplitude of the motion increases along the train set and decreases in the tail part. For the case of short train formation with 7 or 10cars, sway does not happen. But in the case of longer train formation with 16 or 20 cars, sway was found.