• Geomechanics and Engineering
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• 제23권1호
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• pp.1-13
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• 2020

To give a solution for seismic stability of tunnel faces subjected to earthquake ground shakings, the pseudo-dynamic approach is originally introduced to analyze tunnel face stability in this study. In the light of the upper-bound theorem of limit analysis, an advanced three-dimensional mechanism combined with pseudo-dynamic approach is proposed. Based on this mechanism, the required support pressure on tunnel face can be obtained by equaling external work rates to the internal energy dissipation and implementing an optimization searching procedure related to time. Both time and space feature of seismic waves are properly accounted for in the proposed mechanism. For this reason, the proposed mechanism can better represent the actual influence of seismic motion and has a remarkable advantage in evaluating the effects of vertical seismic acceleration, soil amplification factor, seismic wave period and initial phase difference on tunnel face stability. Furthermore, the pseudo-dynamic approach is compared with the pseudo-static approach. The difference between them is illustrated from a new but understandable perspective. The comparison demonstrates that the pseudo-static approach is a conservative method but still could provide precise enough results as the pseudo-dynamic approach if the value of seismic wavelengths is large or the height of soil structures is small.

• Structural Engineering and Mechanics
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• 제24권1호
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• pp.91-105
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• 2006

In this paper, post-earthquake capacity evaluation method of reinforced concrete buildings was studied. Substructure pseudo-dynamic test and static loading test of first story column in a four-story R/C building was carried out in order to investigate the validity of the evaluation method proposed in the Damage Assessment Guideline (JBDPA 2001). In pseudo-dynamic test, different levels of damage were induced in the specimens by pre-loading, and input levels of seismic motion, at which the specimens reached to the ultimate stage, were examined. From the experimental result, no significant difference in damage levels such as residual crack width between the specimens under static and pseudo-dynamic loading was found. It is shown that the seismic capacity reduction factors ${\eta}$ can provide a reasonable estimation of post-earthquake seismic capacity of R/C buildings suffered earthquakes.

• 대한토목학회논문집
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• 제12권4_1호
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• pp.77-85
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• 1992

유사동적실험은 시험체에 대한 물리적인 실험에 이론적인 수치해석방법을 접목시킨 실험기법으로서, 특히 규모가 큰 시험체에 대하여 진동대실험 보다 효율적으로 지진응답실험을 수행할 수 있도록 최근에 개발된 방법이다. 본 연구에서는 유사동적실험 수행과정에서 발생하는 실험오차를 분석하여 실험결과를 보정함으로서, 내진성능실험을 위해서 유사동적실험기법을 광범위하게 적용할 수 있는 가능성을 제시하고자 한다.

• Imaging Science in Dentistry
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• 제36권4호
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• pp.199-206
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• 2006

Purpose: The purpose of this study was to evaluate comparison of static MRI and pseudo-dynamic (cine) MRI in temporomandibular joint (TMJ) disorder patients. Materials and Methods: In this investigation, 33 patients with TMJ disorders were examined using both conventional static MRI and pseudo-dynamic MRI. Multiple spoiled gradient recalled acquisition in the steady state (SPGR) images were obtained when mouth opened and closed. Proton density weighted images were obtained at the closed and open mouth position in static MRI. Two oral and maxillofacial radiologists evaluated location of the articular disk, movement of condyle and bony change respectively and the posterior boundary of articular disk was obtained. Results: No statistically significant difference was found in the observation of articular disk position, mandibular condylar movement and posterior boundary of articular disk using static MRI and pseudo-dynamic MRI (P<0.05). Statistically significant difference was noted in bony changes of condyle using static MRI and pseudo-dynamic MRI (P<0.05). Conclusion: This study showed that pseudo-dynamic MRI didn't make a difference in diagnosing internal derangement of TMJ in comparison with static MRI. But it was considered as an additional method to be supplemented in observing bony change.

• Earthquakes and Structures
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• 제23권4호
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• pp.353-361
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• 2022

The dynamic behavior of a single pile was investigated by using analytical and numerical studies. The focus of this study was to develop the dynamic p-y curve of a pile for pseudo-static analysis considering the shear wave velocity of the soil by using three-dimensional numerical analyses. Numerical analyses were conducted for a single pile in dry sand under changing conditions such as the shear wave velocity of the soil and the acceleration amplitudes. The proposed dynamic p-y curve is a shape of hyperbolic function that was developed to take into account the influence of the shear wave velocity of soil. The applicability of pseudo-static analysis using the proposed dynamic p-y curve shows good agreement with the general trends observed by dynamic analysis. Therefore, the proposed dynamic p-y curve represents practical improvements for the seismic design of piles.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.151-158
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• 2000

The use of unconditionally stable implicit time integration techniques for pseudo-dynamic tests has been recently proposed and advanced by several researchers such as Thewalt and Mahin Nakashima and Shing. The developed implicit algorithms are based on a-Method of Hugest et al. In this paper a concise summary and explanation of implicit method for Pseudo dynamic test is presented. Especially The a-C method developed by shing at al. has been in-depth evaluated for this study. Important parameters of the a-C method have been analyzed by the simulation test.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.617-622
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• 2000

The use of unconditionally stable implicit time integration techniques for pseudo-dynamic test has been recently proposed and advanced by several researchers such as Thewalt and Mahin, Nakashima and Shing, etc. The developed implicit algorithms are based on the $\alpha$-Method of Huges et al. In this paper, a concise summary and explanation of implicit method for Pseudo dynamic tese is presented. Especially, The $\alpha$-C method developed by shing et al. has been in-depth evaluated for this study. Important parameters of the $\alpha$-C method have been analyzed by the simulation test.

• Geomechanics and Engineering
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• 제3권4호
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• pp.255-266
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• 2011

Knowledge of seismic earth pressure against rigid retaining wall is very important. Mononobe-Okabe method is commonly used, which considers pseudo-static approach. In this paper, the pseudo-dynamic method is used to compute the distribution of seismic earth pressure on a rigid cantilever retaining wall supporting dry cohesionless backfill. Planar rupture surface is considered in the analysis. Effect of various parameters like wall friction angle, soil friction angle, shear wave velocity, primary wave velocity, horizontal and vertical seismic accelerations on seismic earth pressure have been studied. Results are presented in terms of tabular and graphical non-dimensional form.

• 한국지진공학회논문집
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• 제6권2호
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• pp.21-28
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• 2002

Ductile behavior and strength of concrete-filled steel(CFS) piers was supported by many quasi-static cyclic loading tests. This test method, however, only estimates the member′s deformation capacity under escalating and repetitive displacement and ignores dynamic and random aspects of an earthquake load. Therefore, to understand complete seismic behavior of the structure against an earthquake, dynamic tests such as shaking table test and pseudo-dynamic tests are required as well as quasi-static tests. In this paper, following "Seismic Performance of Concrete-Filled Steel Piers Part I : Quasi-Static Cyclic Loadint Test", the seismic behavior of CFS and steel piers designed for I-Soo overpass in Seoul in investigated by the pseudo-dynamic test. In addition, the residual strength of both piers after an earthquake is estimated by the quasi-static test. The results show that both piers have satisfactory ductility and strength against well-known EI Centro earthquake although the CFS pier has better strength and energy dissipation than the steel pier.

• 전자공학회논문지
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• 제52권1호
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• pp.111-120
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• 2015

HDR(high dynamic range) 영상 생성은 실세계의 고명암비 영상을 재현하는 방법이다. Exposure fusion은 여러 HDR 영상 생성방법 중 한 가지로 true-HDR 영상을 생성하지 않고, 바로 pseudo-HDR 영상을 생성하는 방법이다. 그러나 노출이 다른 여러 입력영상들 중에서 이동하는 물체가 존재하면 잔상 효과가 발생하여 pseudo-HDR 영상의 화질 열화를 가져온다. 이러한 단점을 해결하기 위해 본 논문에서는 시간 영역에서 일치성 평가를 통한 무 잔상 exposure fusion을 제안하였다. 먼저 다중 역치 및 밝기를 이용한 비트맵과 색도 일관성 맵을 이용하여 각 입력 영상들간의 일치성을 평가하였고, 이를 시간 영역 가중치 맵으로 나타내었다. 그리고 기존 exposure fusion에서의 공간 영역 가중치 맵과 결합하여 최종 가중치 맵을 생성하였다. 마지막으로 각각 입력 영상에 최종 가중치 맵을 적용한 후, 합성하여 잔상이 제거된 pseudo-HDR 영상을 생성하였다. 실험을 통해 제안된 방법의 pseudo-HDR이 기존의 방법보다 잔상이 더 많이 제거되어 화질이 개선됨을 확인하였고, 객관적인 평가 방법인 기준 영상 대비 오차도 더 적게 나타남을 확인하였다.