• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9C
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• pp.1244-1251
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• 2004

In this paper, we propose an efficient dynamic coding scheme by using multiple code words in H.264/A VC entropy coding. The exponential Golomb (Exp-Golomb) code words used in H 264/A VC do not reflect enough the symbol distributions of the combined syntax element in [7] due to their static probability distribution characteristics However, the multiple codewords in this paper have different statistical characteristics. we propose a dynamic coding scheme by using selectively among multiple codewords to encode the combined syntax clement according to given image sequences. Simulation results show that our proposed scheme outperforms the existing [7] me in compression efficiency without loss of quality.

• Journal of Korean Society of Transportation
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• v.20 no.3
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• pp.129-147
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• 2002

This paper presents a variational equality formulation by Providing new dynamic route choice condition for a link-based dynamic traffic assignment model. The concepts of used paths, used links, used departure times are employed to derive a new link-based dynamic route choice condition. The route choice condition is formulated as a time-dependent variational equality problem and necessity and sufficiency conditions are provided to prove equivalence of the variational equality model. A solution algorithm is proposed based on physical network approach and diagonalization technique. An asymmetric network computational study shows that ideal dynamic-user optimal route condition is satisfied when the length of each time interval is shortened. The I-394 corridor study shows that more than 93% of computational speed improved compared to conventional variational inequality approach, and furthermore as the larger network size, the more computational performance can be expected. This paper concludes that the variational equality could be a promising approach for real-time application of a dynamic traffic assignment model based on fast computational performance.

• Tunnel and Underground Space
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• v.22 no.2
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• pp.77-85
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• 2012

In a material, micro-cracks can be progressively occurred, propagated and finally lead to failure when it is subjected to cyclic or periodic loading less than its ultimate strength. This phenomenon, fatigue, is usually considered in a metal, alloy and structures under repeated loading conditions. In underground structures, a static creep behavior rather than a dynamic fatigue behavior is mostly considered. However, when compressed air is stored in a rock cavern, an inner pressure is periodically changed due to repeated in- and-out process of compressed air. Therefore mechanical properties of surrounding rock mass and an inner lining system under cyclic loading/unloading conditions should be investigated. In this study, considering an underground lined rock cavern for compressed air energy storage (CAES), the mechanical properties of a lining system, that is, concrete lining and plug under periodic loading/unloading conditions were characterized through cyclic bending tests and shear tests. From these tests, the stability of the plug was evaluated and the S-N line of the concrete lining was obtained.

• Journal of the Korean Geotechnical Society
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• v.39 no.12
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• pp.37-46
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• 2023

Dynamic soil properties are essential factors for predicting the detailed behavior of the ground. However, there are limitations to gathering soil samples and performing additional experiments. In this study, we used an artificial neural network (ANN) to predict dynamic soil properties based on static soil properties. The selected static soil properties were soil cohesion, internal friction angle, porosity, specific gravity, and uniaxial compressive strength, whereas the compressional and shear wave velocities were determined for the dynamic soil properties. The Levenberg-Marquardt and Bayesian regularization methods were used to enhance the reliability of the ANN results, and the reliability associated with each optimization method was compared. The accuracy of the ANN model was represented by the coefficient of determination, which was greater than 0.9 in the training and testing phases, indicating that the proposed ANN model exhibits high reliability. Further, the reliability of the output values was verified with new input data, and the results showed high accuracy.

• Journal of the Korean Geotechnical Society
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• v.30 no.6
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• pp.5-21
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• 2014

It has been pointed out that the collapses of unsaturated road embankments caused by earthquake are attributed to high water content caused by the seepage of the underground water and/or the rainfall infiltration. Hence, it is important to study influences of water content on the dynamic stability and deformation mode of unsaturated road embankments for development of a proper design scheme including an effective reinforcement to prevent severe damage. This study demonstrates dynamic centrifugal model tests with different water contents to investigate the effect of water content on deformation and failure behaviors of unsaturated road embankments. Based on the measurement of displacement, the pore water pressure and the acceleration during dynamic loading, dynamic behavior of the unsaturated road embankments with about optimum water content and the higher water content than the optimum one have been examined. In addition, an image analysis has revealed the displacement field and the distributions of strains in the road embankment, by which deformation mode of the road embankment with higher water content has been clarified. It has been confirmed that in the case of higher water content the settlement of the crown is large mainly owing to the volume compression underneath the crown, while the small confining pressure at the toe and near the slope surface induces large shear deformation with volume expansion.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.2
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• pp.23-29
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• 1989

The strain rate-sensitive constitutive models of steel and concrete were incorporated into a refined analytical procedure for loading rate-dependent axial/flexural analysis of reinforced concrete beam-columns. The predictions of the analytical technique compared well with both quasi-static and dynamic test results on reinforced concrete elements.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.49-58
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• 2010

This paper presents experimental results of a series of 1-g shaking table model tests performed on end-bearing single piles and pile groups to investigate the effect of particle size on the dynamic behavior of soil-pile systems. Two soil-pile models were tested twice: first using Jumoonjin sand, and second using Australian Fine sand. In the case of single-pile models, the lateral displacement was almost within 1% of pile diameter which corresponds to the elastic range of the pile. The back-calculated p-y curves show that the subgrade reaction of the Jumoonjin-sand-model ground was larger than that of the Australian Fine-sand-model ground at the same displacement. This phenomenon means that the stress-strain behavior of Jumoonjin sand was initially stiffer than that of Australian Fine sand. This difference was also confirmed by resonant column tests and compression triaxial tests. And the single pile p-y backbone curves of the Australian fine sand were constructed and compared with those of the Jumoonjin sand. As a result, the stiffness of the p-y backbone curves of Jumunjin sand was larger than those of Australian fine sand. Therefore, using the same p-y curves regardless of particle size can lead to inaccurate results when evaluating dynamic behavior of soil-pile system. In the case of the group-pile models, the lateral displacement was much larger than the elastic range of pile movement at the same test conditions in the single-pile models. The back-calculated p-y curves in the case of group pile models were very similar in both sands because the stiffness difference between the Jumoonjin-sand-model ground and the Australian Fine-sand-model ground was not significantly large at a large strain level, where both sands showed non-linear behavior. According to a series of single pile and group pile test results, the evaluation group pile effect using the p-multiplier can lead to inaccurate results on dynamic behavior of soil-pile system.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.4
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• pp.225-243
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• 2014

As the economic matters are involved, applying the WEC, which is used for controlling waves as well as utilizing the wave energy on existing breakwater, is preferred rather than installing exclusive WEC. This study examines the OWC mounted on a pressurized air chamber floating breakwater regarding the functionality of both breakwater and wave-power generation. In order to verify the performance as a WEC, the velocity of air flow from pressurized air chamber to WEC has to be evaluated properly. Therefore, numerical simulation was implemented based on BEM from linear velocity potential theory as well as Boyle's law with the state equation to analyze pressurized air flow. The validity of the obtained values can be determined by comparing the previous results from numerical analysis and empirically obtained values of different shapes. In the actual numerical analysis, properties of wave deformation around OWC system mounted on fixed type and floating type breakwaters, motions of the structure with air flow velocities are investigated. Since, the wind power generating system can be hybridized on the structure, it is expected to be applied on complex power generation system which generates both wind and wave power energy.

• Journal of Broadcast Engineering
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• v.21 no.3
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• pp.349-356
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• 2016

In this paper, we propose an efficient assignment method that assigns quantization parameter (QP) in accordance with group of picture (GOP) structure given in HEVC encoder. Each video frames can have difference QP values based on given GOP configuration for HEVC encoding. Particularly, for important frames we can assign low QP values, and vice versa. However, there has not been thorough investigation on efficient QP assignment method by far. Even in HEVC reference software encoder, only monotonic QP assignment method is employed. Thus, the proposed method assign adaptive QP values to each GOP so that temporal dynamic activity between GOPs can be exploited. Through the experiment, the proposed method showed a 7.3% gain of compression performance in terms of BD-rate compared to HEVC test model (HM) in low-delay configuration, and outperformed the existing QP assignment study on average.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.402-410
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• 2022

The present study introduces a calibration method of the CSC model implemented in the LS-DYNA program for considering the material properties of ultra-high performance concrete(UHPC). Based on previous experimental studies, various parameters, which constitute three shear failure surfaces, pressure-volumetric strain curve, fracture energy, dynamic increase factor(DIF), and so on, are modified. Then, the proposed calibration method is verified by comparing the numerical result with the experimental data through the single element analysis. In addition, based on the established finite element models, the applicability of the calibrated CSC model is examined for UHPC structures subjected to impact and blast loadings.