• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.222-227
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• 2004

Korean High Speed Train(KHST) has been tested on the high speed test line in Osung site, since it was developed through the G7 Project Plan in 2002. It was also tested on the conventional line such as KyongBu and Honan Line to know the possibility of increasing the limited speed for the high speed trains. This paper introduces the method to improve the speed on the conventional line with body lateral acceleration among the several considered issues and explains the parameters related to those analysis, such as the cant deficiency, the radius of curve, speed and etc. When a train pass on the curved track, the lateral accelerations of body are divided into the quasi-static and the maximum accelerations according to the UIC 518 which is the international specification for testing and approval of railway vehicles from the point of view of their dynamic behaviour, especially for safety and ride comfort. This paper shows that it is safe and comfort from the results of test when KHST runs on the conventional line with the curves and proposes that the limited speed of conventional curved line could be changed to a little higher speed if the analysises of other fields are completed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.7
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• pp.548-554
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• 2003

This study alms to investigate the dynamic properties of express buses in the very low frequencies which cause motion sickness Incidence. Since passengers often use express buses for long distance traveling. it is a critical point whether the ride give rise to motion sickness or not. In the study accelerations at the three Points on the floor of the six test vehicles were measured during the driving at constant speeds. By applying the frequency weighting corves suggested in ISO 26.31-1, the Physical quantity of accelerations were changed into the perceptual amount used to judge quantitatively the incidence of motion sickness. Motion sickness dose values were calculated from the frequency weighted time history of acceleration signals, and compared between the vehicles, driving conditions. and the seat positions in the bus. During the 50 minutes' driving on the public road and high ways. the vomiting incidence ratios were seen to range from 0.4 to 0.8 ％. which is equivalent to 2.4 to 4.8 ％ for 5 hours' driving. Unlike the very smooth road conditions considered in this work, motion sickness dose values encountered in real situations are expected to increase.

• Advances in Automotive Engineering
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• v.1 no.1
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• pp.1-20
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• 2018

The aim of this study is the optimization of the parameters of interconnected Hydro-Pneumatic (HP) suspension system of a three-axle vehicle for ride comfort and handling. For HP suspension systems of equivalent vertical stiffness and damping characteristics, interconnected HP suspension systems increase roll and pitch stiffness and damping characteristics of the vehicle as compared to unconnected HP suspension systems. Thus, they result in improved handling and braking/acceleration performances of the vehicle. However, increased roll and pitch stiffness and damping characteristics also increase roll and pitch accelerations, which in turn result in degraded ride comfort performance. Therefore, in order to improve both ride comfort and vehicle handling performances simultaneously, an optimum parameter set of an interconnected HP suspension system is obtained through an optimization procedure. The objective function is formed as the sum of the weighted vertical accelerations according to ISO 2631. The roll angle, one of the important measures of vehicle handling and driving safety, is imposed as a constraint in the optimization study. Upper and lower parameter bounds are used in the optimization in order to get a physically realizable parameter set. Optimization procedure is implemented for a three-axle vehicle with unconnected and interconnected suspension systems separately. Optimization results show that interconnected HP suspension system results in improvements in both ride comfort and vehicle handling performance, as compared to the unconnected suspension system. As a result, interconnected HP suspension systems present a solution to the conflict between ride comfort and vehicle handling which is present in unconnected suspension systems.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.4
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• pp.154-162
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• 2004

In this study, a mathematical model for analyzing the shifting transients of the passenger car with an automatic transmission is proposed. The proposed model comprises a power transmission system and a vehicle system, which are coupled. In order to extract the modeling parameters, on-road car test is carried out. The model is composed of a detailed powertrain, an engine/AT housing, a simplified suspension system, tires and a vehicle body model. On the test, the vehicle accelerations and pitch ratio are measured by using accelerometers and a gyro sensor. The speeds, the brake signal, and the throttle position are taken from sensors which already exist in the vehicle. Considering natural ftequencies, which is calculated from the measured accelerations, and the characteristic equation, vehicle model parameters are identified. Dynamic behaviors during upshift or downshift are simulated using the proposed vehicle model. By comparing and analyzing the simulation result and on-road car test data, the vibration of the Engine/AT housing influences the shifting transients. The effect of model parameters are also studied. Among model parameters, the location of engine mountings influences the vibration of the vehicle body.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.8
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• pp.741-748
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• 2004

The vibration and buckling characteristics of the capsule for fuel irradiation test are studied. The natural frequencies of the capsule in air and under water are obtained by modal testing and finite element (FE) analysis using ANSYS program, and accelerations with flow are measured to estimate the compatibility with the operation requirement of the HANARO reactor. The experimental fundamental frequencies of the capsule in the x and z direction are 8.5 Hz and 8.75 Hz in air, and 7.5 Hz and 7.75 Hz under water, respectively. The maximum amplitude of accelerations under the normal operating condition is measured as 11.0 m/s$^2$ that is within the allowable vibrational limit(18.99 m/s$^2$) of the reactor structure. Also, the maximum displacement at 100％ flow is calculated as 0.13 mm which is not interference with other nearby structures. FE analysis results show that the natural frequencies are found to be similar to those of the modal testing when three supporting parts are considered as simply supported conditions. From the buckling analysis, when the loading tool is applied, the critical buckling load of the capsule is 233 N.

• Journal of the Society of Disaster Information
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• v.7 no.3
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• pp.190-197
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• 2011

In this paper, an analytical and experimental study is performed in order to determine the effects of interaction between a vehicle and a structure. For this purpose, a wheel tracking machine and an adequate single span bridge are designed. Results presented in the paper show that the real vehicle tracking accelerations including the interaction between the vehicle and the structure produce additional effects on the dynamic behavior of the structure including reversal and contrary behavior. Also, the interaction between the vehicle and the bridge is reproduced by applying the identified real vehicle tracking accelerations to a general finite element analysis program.

• Journal of Biosystems Engineering
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• v.37 no.6
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• pp.359-364
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• 2012

Purpose: This study was conducted to analyze the vibration absorption effect for the agricultural product transportation-trailer equipped with vibration absorbable connecting hitch, leaf spring suspension, and shock absorber simultaneously (HLS), comparing with the trailer equipped with vibration absorbable connecting hitch only(H), trailer equipped with connecting hitch and leaf spring suspension (HL), and existing trailer with no vibration absorption device (E). Methods: Vertical accelerations were measured at driver seat and front, middle, rear parts of trailer bottom with no load for 4 types of transportation-trailer, and analyzed using FFT analyzer. Results: The magnitude of average vibration accelerations occurred up to 20 Hz, at this low frequencies the severe damage for agricultural products could be represented, was lower (maximum 6 times) for HLS trailer compared with H trailer. And vibration absorption effect for HLS trailer was also higher up to 40-80 Hz and 80-100 Hz, but the difference was less. At driver seat, the vibration absorption effect was high severely for HL and HLS trailer, and the magnitude of vibration acceleration was showed less difference in comparing at trailer bottom. Conclusions: From the test results, it could be recommended that the agricultural products transportation trailer should be equipped with vibration absorption device of HLS.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.7_spc
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• pp.425-434
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• 2016

This study investigates important parameters used to determine an effective peak ground acceleration (EPGA) based on the characteristics of response spectra of historical earthquakes occurred at Korean peninsula. EPGAs are very important since they are implemented in the Korean Building Code for the seismic design of new structures. Recently, the Gyeongju earthquakes with the largest magnitude in earthquakes measured at Korea took place and resulted in non-structural and structural damage, which their EPGAs should need to be evaluated. This paper first describes the basic concepts on EPGAs and the EPGAs of the Gyeongju earthquakes are then evaluated and compared according to epicentral distances, site classes and directions of seismic waves. The EPGAs are dependant on normalizing factors and ranges of period on response spectrum constructed with the Gyeongju earthquake records. Using the normalizing factors and the ranges of period determined based on the characteristics of domestic response spectra, this paper draw a conclusion that the EPGAs are estimated to be about 30 % of the measured peak ground accelerations (PGA).

• Geomechanics and Engineering
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• v.7 no.1
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• pp.87-103
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• 2014

This study investigated the effect of soil-structure interaction (SSI) on the response of base-isolated buildings. Seismic isolation can significantly reduce the induced seismic loads on a relatively stiff building by introducing flexibility at its base and avoiding resonance with the predominant frequencies of common earthquakes. To provide a better understanding of the movement behavior of multi-story structures during earthquakes, this study analyzed the dynamic behavior of multi-story structures with high damping rubber bearing (HDRB) behavior base isolation systems that were built on soft soil. Various models were developed, both with and without consideration of SSI. Both the superstructure and soil were modeled linearly, but HDRB was modeled non-linearly. The behavior of the specified models under dynamic loads was analyzed using SAP2000 computer software. Erzincan, Marmara and Duzce Earthquakes were chosen as the ground motions. Following the analysis, the displacements, base shear forces, top story accelerations, base level accelerations, periods and maximum internal forces were compared in isolated and fixed-base structures with and without SSI. The results indicate that soil-structure interaction is an important factor (in terms of earthquakes) to consider in the selection of an appropriate isolator for base-isolated structures on soft soils.

• Advances in concrete construction
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• v.5 no.4
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• pp.407-422
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• 2017

Evaluating seismic performance of urban structures for future earthquakes is one of the key prerequisites of rehabilitation programs. Irregular structures, as a specific case, are more susceptible to sustain earthquake damage than regular structures. The study here is to identify damage states of vertically irregular structures using the well-recognized Park-Ang damage index. For doing this, a regular 3-story reinforced concrete (RC) structure is first designed based on ACI-318 code, and a peak ground acceleration (PGA) of 0.3 g. Some known vertical irregularities such as setback, short column and soft story are then applied to the regular structure. All the four structures are subjected to seven different earthquakes accelerations and different amplitudes which are then analyzed using nonlinear dynamic procedure. The damage indices of the structures are then accounted for using the pointed out damage index. The results show that the structure with soft story irregularity sustains more damage in all the earthquake records than the other structures. The least damage belongs the regular structure showing that different earthquake with different accelerations and amplitudes have no significant effect on the regular structures.