• The Journal of Engineering Research
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• v.6 no.1
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• pp.53-63
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• 2004

In this paper, influence of shear on the seismic performance and failure mode of reinforced concrete piers subjected to earthquake loading is investigated. Comparative study has been carried out for reinforced concrete column tests to verify the shear-axial interaction model presented in this paper. Comparison shows that predicted shear hysteretic response agrees well with the test results. Also conducted is a nonlinear time-history analysis of a reinforced concrete bridge damaged by the Kobe earthquake using the current development. Displacement response for piers reveals that maximum displacement is considerably increased due to the effect of shear coupled with axial force variation, which leads to overall stiffness degradation and period elongation. It is therefore concluded that the response considering both shear and axial force gives better explanation regarding the seismic damage evaluation of reinforced concrete bridge piers.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.311-312
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• 2022

최근 발생한 경주 및 포항 지진으로 인해 다수의 매립배관 손상이 보고되었다. 벨로우즈 신축관이음은 기하학적 특성으로 인해 진동 및 침하 등으로 인한 손상을 저감시킬 수 있다. 벨로우즈 신축관이음관의 내진 성능평가에 대한 실험적 혹은 해석적 연구는 미미한 상황이다. 본 연구는 벨로우즈 신축이음관의 내진성능을 분석하기 위해 반복하중 기반의 실험적 연구를 수행하였다. 또한 실험결과를 기반으로 3차원 유한요소 모델을 구축하였으며 실험과 해석에서 얻어진 하중-변위 관계를 비교하였다. 해석 모델에서 전체적인 강성이 큰 것으로 나타났으며 최대 변위가 작용할 때 에너지 소산량은 약 10% 가량 큰 것으로 나타났다.

• Composites Research
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• v.22 no.1
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• pp.1-8
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• 2009

In this paper low-velocity impact response and damage of composite laminates is analytically investigated. A modified displacement field of plate considering initially loaded in-plane strain is proposed. From the displacement field a finite element equation on structural behavior of composite laminate is newly induced and a computational program is coded. Numerical results using the FEM code is compared with the numerical ones from reference. Additional numerical analysis is performed on another impact condition and effect of initial in-plane load is reviewed. Potential delamination damage area in the first inter-ply surface from bottom of laminate is approximated and effect of initial in-plane load and impact condition is also reviewed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.707-714
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• 2011

The inter-story drift ratio is used to evaluate the damage of buildings by the earthquake. This is known that as the inter-story drift ratio decreases, the seismic damage decreases. Although to reduce the inter-story drift ratio is the important issue in the seismic design, no practical inter-story drift design method has bean developed. This study presents an optimal inter-story drift design method to improve the seismic performance of the steel moment frames using the resizing algorithm. The objective function of the proposed method is to minimize the differences of the inter-story drift ratios so that the inter-story drift ratios of the building could be distributed evenly and be reduced. Because this method redesigns the sectional properties of structural members base on the displacement participation factor calculated by the unit-load method, this can improve the seismic performance of the structure without the iterative structural analysis. The efficiency of this algorithm was demonstrated by the application to steel moment frames.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.4
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• pp.247-256
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• 2004

The damage curves for the 2-story shear building to the impulsive rectangular loads were established with the peak load and Impulse ratio producing the critical displacement. The convolution integrations with the Impulse response matrix and the loads were used to find the responses of the building. The impulse response matrix required in the calculations of the convolution integration were found with the mode superposition method It is shown from the established damage curves that the responses of the top and bottom floor are sensitive to the magnitude and the impulse of the loads respectively.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.304-310
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• 2002

배 포장용 골판지 상자의 자유낙하 실험을 통하여 완충재로써의 골판지 상자에 대한 충격력을 분석하기 위한 시스템을 구성하고 계측 및 분석용 컴퓨터 프로그램을 작성하여 자유낙하에 의한 배 골판지 포장상자의 충격력을 분석하였으며, 배 골판지 포장상자의 낙하높이에 따른 배의 손상정도는 낙하높이가 높아짐에 따라 손상이 심하고 낙하높이가 낮은 25cm에서도 진동에 의한 손상지수보다는 훨씬 큼을 알 수가 있었다. 이것은 자유낙하에 의한 골판지의 충격력이 배에 전달되어 멍이 발생하는 것으로, 진동에 의한 변위 증폭 및 압상에 의한 손상보다 낙하 충격력에 의한 손상이 더 큰 것을 알 수가 있었으며, 배 골판지 포장상자의 적재 및 하역 작업시에는 낮은 낙하높이에서도 포장상자를 떨어뜨리지 않도록 주의를 하여야 할 것이다.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.11-21
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• 2016

Recently, structure safety management techniques using cutting-edge technology(Displacement senor, sensor of acceleration) has emerged as an important issue owing to the aging of infrastructure such as bridge and building. In general, the structural monitoring system for structure safety management is based on IT technology and it is expensive to install. In this paper developed an image-based structure dynamic characteristic analysis system prototype to assess the damage of structure in a more cost-effective way than traditional structure health monitoring system. The inspector can take a video of buildings or other structures with digital camera or any other devices that is passible to take video, and then using NCC calculation for image processing technique to get natural frequency. This system is analysis of damage of the structure using a compare between the frequency response ratio and functions when problems are occurs send alarm to administrator. This system is easier to install and remove than previous monitoring sensor in economical way.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.2
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• pp.161-173
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• 2013

When the ground is excavated near the pre-existing structures due to the region restricted condition such as urban area, the ground will be released by the excavation and the temporary wall will be deformed depending on the earth pressure. In this case, issues can be created in terms of stability of pre-existing structures. Firstly, the laboratory model tests were carried out to investigate the ground surface settlement due to the ground excavation according to the excavation methods in this study. Using the ground surface settlement results from model tests, numerical analyses were carried out to study the structure deformation due to the ground excavation according to the excavation methods. Finally, using the structure deformation results from numerical analysis, the damage assessment of structures was carried out by using the strain damage estimation criterion.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.9-13
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• 2009

Modal parameters including resonant frequencies and mode shapes are heavily utililized in most damage identification throries for structural health monitoring. However, extracting modal parameters from dynamic responses needs postprocessing which inevitably involves errors in curve-fitting resonants as well as transforming the domain of responses. In this paper, the applicability of a damage identification method based on free vibration responses to the in-sevice responses is experimentally verified. The experiment is performed via applying periodic and nonperiodic moving loads to a simply supported beam and displacement responses are measured. The moving load is simulated using steel balls and a downhill device. The damage identification results show that the in-service response may be applicable to identifying damage in the beam.

• The Journal of Engineering Geology
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• v.26 no.2
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• pp.187-196
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• 2016

We conducted three-dimensional finite element analysis to predict the presence of upcoming fault zones during tunneling. The analysis considered longitudinal displacements measured at tunnel face, and used 28 numerical models with various fault attitudes. The x-MR (moving range) control chart was used to analyze quantitatively the effects of faults distributed ahead of the tunnel face, given the occurrence of a longitudinal displacement. The numerical models with fault were classified as fault gouge, fault breccia, and fault damage zones. The width of fault cores was set to 1 m (fault gouge 0.5 m and fault breccia 0.5 m) and the width of fault damage zones was set to 2 m. The results, suggest that fault centers could be predicted at 2~26 m ahead of the tunnel face and that faults could be predicted earliest in the 45° dip model. In addition, faults could be predicted earliest when the angle between the direction of tunnel advance and the strike of the fault was smallest.