• 대한기계학회논문집A
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• 제30권11호
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• pp.1455-1460
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• 2006

The relationship between fatigue crack growth behavior and cyclic crack tip opening displacement is studied. An elastic-plastic finite element analysis (FEA) is performed to examine the growth behavior of fatigue crack, where the contact elements are used in the mesh of the crack tip area. We investigate the relationship between the reversed plastic zone size and the changes of the cyclic crack tip opening displacement along the crack growth. We investigate the effect of the element size when predict fatigue crack opening behavior using the cyclic crack tip opening displacement obtained from FEA. The cyclic crack tip opening displacement is related to fatigue crack opening behavior.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1273-1276
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• 2005

A displacement magnification mechanism is usually employed in a nano-positioning stage to achieve a large stage motion. A lever mechanism is the most widely used displacement magnifying mechanism. For more large stage motion, double or multiple lever mechanisms can be used. In this case, a more accurate analysis model is needed. This study proposes a more reasonable analysis model for a multiple lever mechanism based on the single lever mechanism model. This paper describes that the high equivalent stiffness of the lever is the most important factor reducing the magnification ratio of the lever mechanism through increasing the deflection of the link and including the axial displacement of the pivot.

• Structural Engineering and Mechanics
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• 제52권6호
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• pp.1225-1256
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• 2014

Calculating the seismic displacement of retaining walls has an important role in the optimum design of these structures. Also, studying the effect of surcharge is important for the calculation of active pressure as well as permanent displacements of the wall. In this regard, some researchers have investigated active pressure; but, unfortunately, there are few investigations on the seismic displacement of retaining walls with surcharge. In this research, using limit analysis and upper bound theorem, permanent seismic displacement of retaining walls with surcharge was analyzed for sliding and overturning failure mechanisms. Thus, a new formulation was presented for calculating yield acceleration, critical angle of failure wedge, and permanent displacement of retaining walls with surcharge. Also, effects of surcharge, its location and other factors such as height of the wall and internal friction angle of soil on the amount of seismic displacements were investigated. Finally, designing charts were presented for calculating yield acceleration coefficient and angle of failure wedge.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.395-402
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• 2000

Recently, the deep excavations have been peformed to utilize the under ground space. As the ground excavation is deeper, the damage of the adjacent structure and the ground occurs frequently. The analysis of the retaining structures is necessary to the safety of the excavation works. There are many methods such as elasto-plastic, FEM, and FDM to analyze the displacement of the retaining structure. The elasto-plastic method is generally used in practice. In this thesis, GEBA-1 program by the Nakamura-Nakajawa elasto-plastic method was developed. The program for Windows was used the Visual Basic 6.0, and the Main of the program consists of three subroutines, SUB1, SUB2, and SUB3. The lateral displacement of the wall was analyzed by the developed program GEBA-1, SUNEX, and EXCAD, and compared with the measured displacement by the Inclinometer(at three excavation work sites). The excavation method of each site is braced retaining wall using H-pile. Each excavation depth is 14m, 14m, or 8.2m. The results of the analyses are the followings ① In the multi-layer soil, the lateral displacement by the GEBA-1 and EXCAD which is considering the distribution of the strut load is equal to the measured displacement. Elasto-plasto programs can't consider the change of the ground water in clay. Therefore, the analysis displacement was expected only 20% of the measured wall displacement. ③ At the final excavation step, the maximum lateral displacement of analysis and field occurred 7∼18m at the 85∼92% of the excavation depth. ④ The maximum lateral displacement in clay, as 50mm, occurred on the ground surface.

• 한국지반환경공학회 논문집
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• 제13권5호
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• pp.25-33
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• 2012

본 연구에서는 흙막이 가시설 공법중 지반의 변위를 억제하고, 토공사 및 구조물 공사의 시공성을 크게 개선한 IPS 흙막이 가시설 공법을 시공한 현장의 계측자료를 바탕으로, 탄소성보법 수치해석 프로그램(EXCAV/W)을 이용하여 수치해석을 실시하였다. 그 결과, 선행하중을 가한 해석치가 평균 13.2% 감소하였으며, 또한 일반적인 해석치보다 현장 계측치는 평균 26.7% 감소하는 것으로 나타났다. 따라서 IPS 흙막이 가시설 공법은 기존 버팀보 공법에 흙막이벽의 수평변위에 대한 안전성을 확보하고 있음을 알 수 있다. 또한 IPS 흙막이 가시설 공법을 이용한 선행하중 효과를 통해 수평변위가 감소하는 것을 확인할 수 있다.

• 한국기계가공학회지
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• 제12권1호
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• pp.97-103
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• 2013

A new precision positioning mechanism for stage was been developed by Displacement Magnification Device(DMD) in this paper. The DMD was composed of the beam and multilayer piezoelectric actuators. The theoretical and experimental analysis of DMD to enlarge displacement more then 50times were discussed. And the 2-axis stage by using displacement amplification apparatus was added in the new DMD, and it was able to do it through finite element analysis and experiment. As the results, the magnification of DMD can be obtained about $100{mu}m$ displacement to the 10V input voltage($1.5{mu}m$). And the about 50nm of linearity error in the $30{mu}m$ measurement range and 20times of the amplification in displacement can be measured. In addition, the experimental results are confirmed the possibility of millimeter displacement characteristics and correspond to finite element analysis results.

• 한국공간구조학회논문집
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• 제24권2호
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• pp.31-41
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• 2024

This study aims to investigate the seismic response of a large span thin shell structures and assess their displacement under seismic loads. The study employs finite element analysis to model a thin shell structure subjected to seismic excitation. The analysis includes eigenvalue analysis and time history analysis to evaluate the natural frequencies and displacement response of the structure under seismic loads. The findings show that the seismic response of the large span thin shell structure is highly dependent on the frequency content of the seismic excitation. The eigenvalue analysis reveals that the tenth mode of vibration of the structure corresponds to a large-span mode. The time history analysis further demonstrates, with 5% damping, that the displacement response of the structure at the critical node number 4920 increases with increasing seismic intensity, reaching a maximum displacement of 49.87mm at 3.615 seconds. Nevertheless, the maximum displacement is well below the allowable limit of the thin shell. The results of this study provide insight into the behaviour of complex large span thin shell structures as elevated foundations for buildings under seismic excitation, based on the displacement contours on different modes of eigenvalues. The findings suggest that the displacement response of the structure is significant for this new application of thin shell, and it is recommended to enhance the critical displacement area in the next design phase to align with the findings of this study to resist the seismic impact.

• 산업경영시스템학회지
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• 제35권4호
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• pp.24-32
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• 2012

Of many approaches to reduce motion analysis errors, the compensation method of anatomical landmarks estimates the position of anatomical landmarks during motion. The method models the position of anatomical landmarks with joint angle or skin marker displacement using the data of the so-called dynamic calibration in which anatomical landmark positions are calibrated in ad hoc motions. Then the anatomical landmark positions are calibrated in target motions using the model. This study applies the compensation methods with joint angle and skin marker displacement to three lower extremity motions (walking, sit-to-stand/stand-to-sit, and step up/down) in ten healthy males and compares their performance. To compare the performance of the methods, two sets of kinematic variables were calculated using different two marker clusters, and the difference was obtained. Results showed that the compensation method with skin marker displacement had less differences by 30~60% compared to without compensation. And, it had significantly less difference in some kinematic variables (7 of 18) by 25~40% compared to the compensation method with joint angle. This study supports that compensation with skin marker displacement reduced the motion analysis STA errors more reliably than with joint angle in lower extremity motion analysis.

• 한국해안·해양공학회논문집
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• 제20권4호
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• pp.413-420
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• 2008

파랑하중은 연약지반을 굴착 치환시킨 후에 축조된 사석경사식 방파제의 안정에 직접적인 영향을 주는 요소이다. 특히 일부 침하를 허용하는 굴착치환 사석경사 방파제에서 침하를 유발하는 주요인으로 지목되었으나, 설계 시 파랑하중에 의한 방파제의 침하에 대한 영향을 검토하여 반영하는 사례가 전무한 상태이다. 따라서 본 연구에서는 파랑하중에 의한 방파제 침하의 영향을 설계에 직접 반영할 수 있도록 수치모형실험을 실시하여 방파제 침하량을 계산한 후 현장계측자료와 비교하였다. 계산값과 실측값은 양호한 일치를 보이는 것으로 나타났다.

• Geomechanics and Engineering
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• 제14권3호
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• pp.241-246
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• 2018

The displacement monitoring data series reconstruction method was developed under equal water level effects based on displacement monitoring data of concrete dams. A dam displacement variation equation was set up under the action of temperature and aging factors by optimized analysis techniques and then the dam displacement hydraulic pressure components can be separated. Through the dynamic adjustment of temperature and aging effect factors, the aging component isolation method of dam displacement was developed. Utilizing the isolated dam displacement aging components, the dam stability model was established. Then, the dam stability criterion was put forward based on convergence and divergence of dam displacement aging components and catastrophe theory. The validity of the proposed method was finally verified combined with the case study.