• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.04a
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• pp.75-80
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• 1998

Dynamic measurements are used rather sparingly to determine the elastic moduli of rock cores and modulus values are not much utilized in design practices. The reason seems to result from the general perception that values obtained by dynamic measurement are much higher (about 10 time) than those determined statically. This paper presents results from dynamic and static tests on rock cores. One of the findings is that both moduli determined by statically and dynamically on a solid rock core agrees well at the same-strain. At different strain levels, the ratio between dynamic and static modult widely varies depending upon micro-cracks and discontinuites of rock cores.

• Transactions of the Society of Information Storage Systems
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• v.11 no.2
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• pp.26-30
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• 2015

Recently, military vehicles are driven with a lot of electronic devices such as radar, antenna, and information storage devices. However, the military vehicles can be exposed to impact easily. Therefore, they have to be designed robustly in order to ensure the stability of the vehicle and the electronic devices. To achieve that, the dynamic behaviors of the military vehicle should be exactly identified. Therefore, in this research, dynamic behaviors of the vehicles were identified by carrying out road tests and we constructed finite element model to analyze the dynamic characteristics of the vehicle.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.375-382
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• 2003

This study, Using Pusan clay, examined a relationship between Dynamic and Static Liquid Tests. The Static Liquid Tests wow carried out based on BS and JIS. The results of the study are summarized as follows. (1) The result of the Dynamic Liquid Limit Test showed that the liquid limit values of air-dried soil were greater than those of oven-dried soil by 4%~15% (2) The liquid limit value of the Static Liquid Limit Test was greater than that of the Dynamic Liquid Limit Test by 2%~9%. The following equations show the relationship between the two values WL,Fall(JIS) = 0.961ㆍWL,Cas. + 4.209 WL,Fall(BS) = 0.969ㆍWL,Cas + 5.024 (3) The liquid limit value of BS was greater than that of JIS by 1%~6%. The following equation shows the relationship between the two values.

• Structural Engineering and Mechanics
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• v.11 no.6
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• pp.651-662
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• 2001

In order to investigate the seismic behavior and seismic design methods in the transverse direction of a shield tunnel, a series of model shaking table tests and a two-dimensional finite element dynamic analysis on the tests are carried out. Two kinds of static analytical methods based on ground-tunnel composite finite element model and beam-spring element model are proposed, and the validity of the static analyses is verified by model shaking table tests. The investigation concerns the dynamic response behavior of a tunnel and the ground, the interaction between the tunnel and ground, and an evaluation of different seismic design methods. Results of the investigation indicate that the shield tunnel follows the surrounding ground in displacement and dynamic characteristics in the transverse direction; also, the static analytical methods proposed by the authors can be used directly as the seismic design methods in the transverse direction of a shield tunnel.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.275-283
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• 2002

In this study, the shaking table tests of block systems on the rigid base have been performed to identify the seismic response and the dynamic behavior of the piled multi-block systems. To understand the characteristics of seismic response of piled multi-block systems, it is necessary to understand the dynamic behavior of single block system. Therefore, the skating table test of the single block system has been performed first. Moreover, by performing the shaking table tests of multi-block systems, the characteristics of dynamic behavior of piled multi-block systems have been analyzed. Also in this study, the distinct element method(DEM) has been used to analyze the nonlinear behavior of the piled multi-block systems. The results of the shaking table tests show that the response of the multi-block systems is very complicated. But by using DEM, the behavior of piled multi-block systems has been predicted and described well.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.207-210
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• 2003

This study, using Pyongteak & Tangjin soil, examined a relationship between Dynamic and Static Liquid Limit Tests. The Liquid Limit Tests were carried out based on BS and KS. The results of the study are summarized as follows. The liquid limit value of the Static Liquid Limit Test was greater than that of the Dynamic Liquid Limit Test be 4% - 14%. The following equation shows the relationship between the two values.(Coefficient of Correlation = 0.88) $$BS(LL)=0.7519{\times}KS(LL)+19.174$$

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.249-252
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• 1999

A numerical analysis was perfomed to predict flow curves and dynamic recrystallization behaviors of Al-5%Mg alloy on the basis of results of hot compression tests. The hot compression tests were carried out in the ranges of 350-50$0^{\circ}C$ and 5$\times${{{{ {10 }^{-3 } }}}}~3$\times${{{{ {10 }^{0 } }}}}/sec to obtain the Zener-Hollmon parameter. In the modelling equation the effects os strain hardening and dynamic recrystallization were taken into consideration. A model for predicting the evolution of microstructure in Al-5%Mg alloy during thermomechanical processing was developed in terms of dynamic recrystallization phenomena, The microstructure model was combined with finite element modeling(FEM) to predict microstructure development Model predictions showed good agreement with microstructures obtained in compression tests.

• Structural Engineering and Mechanics
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• v.55 no.2
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• pp.263-280
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• 2015

This paper describes a study of the collision of hard steel spheres against aluminium thin circular plates at speeds up to 140 m/s. The tests were monitored by a high speed camera and a chronoscope, which allowed the determination of the ballistic limit and the plate deformation pattern. Quasi-static material parameters were obtained from tests on a universal testing machine and dynamic mechanical characterization of two aluminium alloys were conducted in a split Hopkinson pressure bar. Using a damage model, the perforation of the plates was simulated by finite element analysis. Axisymmetric, shell and solid elements were employed with various parameters of the numerical analysis being thoroughly discussed, in special, the dynamic model parameters. A good agreement between experiments and the numerical analysis was obtained.

• 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.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.11c
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• pp.129-141
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• 1999

This paper presents the results of plate load test and dynamic load test performed to evaluate the performance of geocell where it is used to reinforce soft subgrade for high-speed railroad. Efficacy of geocell was observed in increase in bearing capacity of subgrade and reduction of thickness of reinforced sub-ballast. Plate load tests were carried out at four different places with varying foundation soil strength as a function of number of geocell layer, type of filler material, thickness of cover soil, and the presence of non-woven geotextile. Dynamic load tests were performed in a laboratory. The test soil chamber consists of, from the bottom, 50 cm thick clayey soil, one layer of geocell filled with crushed stone, 10 cm thick crushed stone cover, reinforced sub-ballast of varying thickness, 35 cm thick ballast. This configuration was determined based on the results of numerical analysis and plate load tests. For each set of the dynamic load tests, loads were applied more than 80,000 times. One layer of geocell underlying a 10 cm thick cover soil led to an increase in bearing capacity three to four times compared to a crushed stone layer of the same thickness substituted for the geocell and cover soil layer. Given the test conditions, the thickness of reinforced sub-ballast can be reduced by approximately 35 cm with the presence of geocell.