• Proceedings of the KSME Conference
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• 2003.11a
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• pp.385-389
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• 2003

Three-dimensional experimental analysis was conducted in the pulverizer simplified isothermal model. The experiment model was constructed on a 1/3.5 scale of 500MW pulverizer. The purpose of this study is to investigate the effect of design parameters on the pulverized coal separator efficiency. Where used pulverized coal separator design parameters are guide vane angle, static classifier angle, dynamic classifier rpm. Taguchi method was used to find the effective design parameters related to pulverized coal separator efficiency. The results of the experiment showed that guide vane angle and dynamic classifier rpm were the design key parameters. In addition to the total number of experiment cases were reduced by Taguchi method.

• Structural Engineering and Mechanics
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• v.59 no.2
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• pp.277-290
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• 2016

This paper investigates the ground vibration induced by high-speed trains moving on multi-span continuous bridges. The dynamic impact factor of multi-span continuous bridges under trainloads was first determined in the parametric study, which shows that the dynamic impact factor will be large when the first bridge vertical natural frequency is equal to the trainload dominant frequencies, nV/D, where n is a positive integer, V is the train speed, and D is the train carriage interval. In addition, more continuous spans will produce smaller dynamic impact factors at this resonance condition. Based on the results of three-dimensional finite element analyses using the soil-structure interaction for realistic high-speed railway bridges, we suggest that the bridge span be set at 1.4 to 1.5 times the carriage interval for simply supported bridges. If not, the use of four or more-than-four-span continuous bridges is suggested to reduce the train-induced vibration. This study also indicates that the vibration in the train is major generated from the rail irregularities and that from the bridge deformation is not dominant.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.374-385
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• 2022

In order to investigate the application of 3D base-seismic isolation system in nuclear power plants (NPPs), comprehensive analysis of constitution and design theory for 3-dimensional combined isolation bearing (3D-CIB) was presented and derived. Four different vertical stiffness of 3D-CIB was designed to isolate the nuclear island (NI) building. This paper aimed at investigating the isolation effectiveness of 3D-CIB through modal analysis and dynamic time-history analysis. Numerical results in terms of dynamic response of 3D-CIB, relative displacement response, acceleration and floor response spectra (FRS) of the superstructure were compared to validate the reliability of 3D-CIB in mitigating seismic response. The results showed that 3D-CIB can significantly attenuate the horizontal acceleration response, and a fair amount of the vertical acceleration response reduction of the upper structure was still observed. 3D-CIB plays a significant role in reducing the horizontal and vertical FRS, the vertical FRS basically do not vary with the floor height. The smaller the vertical stiffness of 3D-CIB is, the better the vertical isolation effectiveness is, whereas, it will increase the displacement and the rocking effect of superstructure. Although the advantage of 3D-CIB is that the vertical stiffness can be flexibly adjusted, it should be designed by properly accounting for the balance between the isolation effectiveness and displacement control including rocking effect. The results of this study can provide the technical basis and guidance for the application of 3D-CIB to engineering structure.

• Journal of Applied Reliability
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• v.17 no.1
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• pp.50-57
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• 2017

Purpose : This paper is a comparative analysis results of the fatigue test for dental implants and accelerated life test by using a static type loading device commonly used in Korea and a dynamic type loading device (universal-joint) recommended by FDA. Methods : Fatigue tests of dental implant is based on ISO 14801 and classified into static load test and dynamic load test. The tests were carried out on three test specimens by four load stress steps under each loading device. For analysis on failure mode such as crack, fracture and permanent deformation of test specimens, we used X-ray three-dimensional computed tomography on test specimens before and after the fatigue tests. The design of the accelerated life test was based on the analysis results of the fatigue life data obtained from the dynamic load test and the statistical analysis software (Minitab ver.15) was used to analyze the appropriate life distribution. Results : As a result of the fatigue tests and the accelerated life tests at same acceleration condition under each test method, the fatigue life under the dynamic type loading device (universal-joint) was shorter than when static type loading device was applied. Conclusion : This paper can be used as a reference when the universal-joint type loading device for implants fatigue test is applied as ISO 14801.

• Earthquakes and Structures
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• v.7 no.2
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• pp.233-250
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• 2014

In this paper, a three dimensional soil-structure interaction (SSI) is numerically simulated using finite element method in order to analyse the foundation moments in annular raft of tall slender chimney structures incorporating the effect of openings in the structure and the effect of soil flexibility, when the structure-soil system is subjected to El Centro (1940) ground motion in time domain. The transient dynamic analysis is carried out using LS-DYNA software. The linear ground response analysis program ProShake has been adopted for obtaining the ground level excitation for different soil conditions, given the rock level excitation. The radial and tangential bending moments of annular raft foundation obtained from this SSI analysis have been compared with those obtained from conventional method according to the Indian standard code of practice, IS 11089:1984. It is observed that tangential and radial moments increase with the increase in flexibility of soil. The analysis results show that the natural frequency of chimney decreases with increase in supporting soil flexibility. Structural responses increase when the openings in the structure are also considered. The purpose of this paper is to propose the need for an accurate evaluation of the soilstructure interaction forces which govern the structural response.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.8
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• pp.945-951
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• 2012

In this study, we analyze the static and dynamic characteristics of a bulk-cement trailer with a simpler structure that carries powders. The commercial software ANSYS is used to prepare a detailed three-dimensional model of the chassis frame and tank body that bear most of the load of a bulk-cement trailer for the finite element analysis. Modal analysis is conducted to examine the dynamic characteristics of the trailer body, and static analysis shows weak links in the structure. Finally, we propose a method to increase the strength of vulnerable areas and to reduce the weight of the trailer by applying the Taguchi method.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.162-171
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• 2012

In this study, a new dynamic interaction analysis method for tilting trains and curved track is presented. Three dimensional lumped parameter vehicle elements are used to model tilting train, and the proposed analysis technique can simulate driving direction change of vehicle, the effect of track cant, wheel-rail contact angle, and tilting angle of tilting trains, etc. The proposed method passed several basic verification tests, and it is expected that the suggested method is applicable for practical problems.

• Structural Engineering and Mechanics
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• v.69 no.5
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• pp.567-577
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• 2019

Guyed steel lattice towers (or guyed masts) are widely used for supporting antennas for telecommunications and broadcasting. This paper presents a numerical study on the static and dynamic response of guyed towers. Three-dimensional nonlinear finite-element models are used to simulate the response. Through performing static pushover analyses and free-vibration (modal) analyses, the effect of different bracing configurations is investigated. In addition, seismic analyses are performed on towers of different heights to study the influence of earthquake excitation time-lag (or the earthquake travel distance between tower anchors) and antenna weight on the seismic response of guyed towers. The results show that the inclusion of time lag in the seismic analysis of guyed towers can influence shear and moment distribution along the height of the mast. Moreover, it is found that the lateral response is insensitive to bracing configurations. The results also show that, depending on the mast height, an increased antenna weight can reduce the tower maximum base shear while other response quantities, such as cables tension force are found to be insensitive to variation in the antenna weight.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.718-723
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• 2007

A three dimensional multibody modeling of a launcher system was developed and dynamic characteristics of the system was carried out. All the components were modeled as rigid bodies, All the components of system, ie; chassis, turret, cage and suspension parts, are modeled as rigid. The force interaction between the ground and tire was modeled as a point contact model. The factors were selected as cause and effect diagram of the MINITAB. To see effect of the stiffness, damping, mass at the launcher system, several cases of suspension parameters were compared and optimal values were selected. The stiffness and the damping coefficient were selected as design variables to minimize the required time for the next fire. The dynamic simulation was carried out using the ADAMS, and the MINITAB was employed for data analysis.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.4
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• pp.12-22
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• 2001

Vehicle driving simulators hale been used in the development and modification of models. A simulator can reduce cost and time through a variety of driving simulations in the laboratory. Recently, driving simulators have begun to proliferate in the automotive industry and the associated research community. This paper presents the hardware and software developed fur a driving simulator of construction vehicles. This effect involves the real-time dynamic analysis of wheel-type excavator, the design and manufacturing of the Stewart platform, an integrated control system of the platform, and three-dimensional graphic modeling of the driving environments.