• Computational Structural Engineering
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• v.11 no.2
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• pp.36-39
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• 1998

국내의 피로파괴(fatigue fracture)나 파괴역학(fracture mechanics)과 같은 분야는 많은 발전이 있었으나 손상역학(damage mechanics)분야의 발전은 미흡하여 이 분야에 대한 이해를 돕기 위하여 손상역학의 역사적 배경, 용어의 정의, 현재의 연구동향, 손상역학의 적용 및 한계에 대하여 간략히 소개하고자 한다. 이 글에서는 전문학술적인 내용은 피하였으며 손상역학 분야에 관심이 있는 이들을 위하여 이 글에서 인용된 저자들의 대표적인 문헌들을 중심으로 간략히 소개하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.500-503
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• 2010

본 논문에서는 산업용 용접구조물의 피로성능 평가를 위한 시간 및 비용 절감형 전산피로시험법을 개발한다. 임의의 하중에 놓인 용접구조물의 성능저하 현상(균열발생 및 진전 등)을 손상역학에 기반하여 역학적으로 기술하고 자체개발한 유한요소해석코드에 탑재하여 이를 전산적으로 시뮬레이션한다. 정도 높은 용접구조물 전산피로시험법의 개발을 위해 용접잔류응력과 재료파라미터를 자체개발한 유한요소해석코드를 통해 구현한다. 개발된 전산피로시험법은 용접구조물의 피로시험 결과와 비교함으로서 제안 기법의 적합성 및 유용성을 검증한다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.347-351
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• 2010

판과 같은 구조물의 손상 감지를 위해, 손상 전 구조물의 임피던스 신호를 기저신호(Baseline impedance signal)로 이용하여 직접적으로 비교하지 않는 새로운 개념의 무기저 손상진단 기법(Reference-free impedance method)을 제시한다. 박막 압전소자(이하 PZT)를 판의 상하 표면에 부착시킨 한 쌍의 병치 PZT를 이용하여 손상으로 인해 모드변환을 일으키는 전기역학적 신호(Electro Mechanical Signatures ; 이하 EMS)를 추출한다. 이 연구에서는 스펙트럼 요소법(Spectral Element Method ; 이하 SEM)을 이용하여 주파수 영역에서 병치된 PZT의 EMS를 파악하기 위한 수치해석을 수행한다. 특히, 손상에 의해 발생된 모드변환 EMSMC를 병치된 PZT의 극성에 기인한 신호분해 기법을 적용하여 추출하고, 분해된 모드변환 EMSMC가 손상의 위치와 크기에 따라 받는 영향을 추가로 분석한다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.315-318
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• 2011

본 논문에서는 구조물 연결부의 실시간 손상 검색을 통해 이상이 감지되었을 경우 자가치유까지 가능한 지능형 볼트접합부 시스템에 관한 실험적 연구결과가 제시되었다. 지능형 센서인 PZT센서의 전기-역학적 커플링 특성을 이용한 전기역학적 임피던스 기반의 구조물 건전성 평가 방법이 사용되었다. 전기역학적 임피던스의 측정을 통한 계측값을 베이스라인 값과 비교하는 손상 평가를 통해 구조물 볼트접합부의 볼트풀림 손상을 진단하고, 손상은 손상지수 RMSD를 통하여 정량화되었다. 볼트접합부의 손상이 감지되었을 경우 형상기억합금(SMA) 와셔에 부착되어있는 히팅 필름에 전원을 가함으로써 형상기억합금에 열을 가하고, 가열된 형상기억합금 와셔는 축방향으로 팽창을 함으로써 잃었던 볼트의 토크력을 회복시켜주었다. 실험 결과, 제안된 전기역학적 임피던스 기반의 구조물 건전성 평가기법과 형상기억합금 와셔 기반의 볼트접합부 자가치유 시스템의 성능 평가와 검증이 이루어졌다.

• Tunnel and Underground Space
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• v.16 no.3 s.62
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• pp.209-217
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• 2006

Literatures on the fracture mechanics and damaged zone of rocks were studied to estimate the excavation and blasting damaged zone for rapid tunneling. Fracture mechanics were applied to explain fracture mechanism and to estimate damaged zone and seemed to be applicable for controlling the fractures.

• Economic and Environmental Geology
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• v.27 no.5
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• pp.499-505
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• 1994

Local stress concentrations often cause new micro-damaging induced by a healed pre-existing defects, and the macro-damage is developed by propagation and coalescence of the micro-damage. The micro-damage causes non-linear deformation in rock material. Considerable work has also been applied to describe mathematically the behavior of cracks under stress. Although these mathematical models can usually be made to agree quite well with the measured data, but it is questionable how well the models describe real rock including microcracks in pre-failure state, such as their micro-damage mechanisms. In the present study, micro-damage initiation and propagation in granitic rock under increasing stress were observed directly. Furthermore, a stress analysis considering the bisphere model was carried out using the homogenization theory to analyze the mechanics of the stress-induced micro-damage.

• Clinics in Shoulder and Elbow
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• v.13 no.1
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• pp.141-145
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• 2010

Purpose: Understanding elbow biomechanics is necessary to understand the pathophysiologic mechanism of elbow injury and to provide a scientific basis for clinical practice. This article provides a summary of key concepts that are relevant to understanding common elbow injuries and their management. Materials and Methods: The biomechanics of the elbow joint can be divided into kinematics, stability and force transmission through the elbow joint. Active and passive stabilizers include bony articular geometry; soft tissues provide joint stability, compression force and motion. Results and Conclusion: Knowledge of elbow biomechanics will help (i) advance surgical procedures and trauma management, (ii) develop new elbow prostheses and (iii) stimulate future research.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.751-759
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• 1994

Concrete contains numerous microcracks initially. The growth and propagation of microcracks cause failure of concrete. These processings are termed as "damage". The concepts of the continuum damage mechanics are presented and the damage evolution law and constitutive equation are derived by using the Helmholz free energy and the dissipation potential by means of the thermodynamic principles. The constitutive equation includes the effects of elasticity, damage and plasticity of concrete. The proposed model successfully predicts the nonlinear behavior of concrete subject to monotonic uniaxial and biaxial loadings.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.57-65
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• 2006

This paper presents hybrid structural damage monitoring system which performs both global damage assessment of structure and damage detection of local structural joints. Hybrid damage monitoring system is composed of vibration-based technique and electro/mechanic impedance technique. Vibration-based technique detects global characteristic change ot structure using modal characteristic change of structure, and electro/mechanical impedance technique detects damage existence of local structural joints using impedance change of PZT sensor. For the verification of the proposed hybrid monitoring system, a series of damage scenarios are designed to loosened bolts situations of the structural joints, and acceleration response and impedance response signatures are measured. The proposed hybrid monitoring system is implemented to monitor global damage-state and local damages in structural joints.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.2
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• pp.257-270
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• 2000

The objective of this study is to develop a damage model based on damage mechanics that can be used to analyze the mechanical behavior of structures with defects and the global behavior of damaged structures. A modified second order damage tensor that can be applied to finite element analysis is used to reflect the effect of damage. The damage stress computed from the effective stress is considered as an additional loading term acting on nodes and can represent the effect of crack surface. The accuracy of the proposed algorithm is verified by comparing the analysis results with the experimental data from other studies and the analysis results based on transverse isotropic theory. The developed damage model is applied to the analyses of structures with cracks under linear elastic condition. The comparisons confirmed that the quantitative analysis of the structural behavior due to crack orientation and multiple sets of cracks is possible. Also, the damage caused by rock excavation and fault zone is analyzed. The results also showed that the developed model can effectively analyze the global behavior of damaged structures.