• 대한안전경영과학회지
• /
• 제13권1호
• /
• pp.1-9
• /
• 2011

It is a significant issue for several country including Korea, where the natural and the weather conditions are severe, to keep the safety against disasters which occur frequently every year, especially in urban region crowded with population. In order to implement suitable and effective measures against various disasters in such area, development of method for evaluation of disaster prevention performance based on various disaster risks and effective disaster damage mitigation technologies is independable. In this paper, methods for hazard evaluation, vulnerability evaluation and loss evaluation, and damage technologies are proposed targetting man-made disaster and natural one like flood, earthquake and tsunami and so on. The method proposed in this paper is based on the research of USA and Japan for man-made disaster and natural disaster. The proposed method will be developed in detail in four years during research period funded by government.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2006년도 추계학술대회 논문집
• /
• pp.31-34
• /
• 2006

이 논문에서는 선관통형 균열을 포함하는 정사각형 평판과 선관통형 균열이 연속체 손상이론을 이용에서 구한 유효 직교 이방성 탄성 물성치의 등가 연속체 모델로 대체된 평판의 모드형상과 고유진동수를 비교하여 SEEP에 기반하여 Lee 등이 [5] 제안한 연속체 손상이론을 검증하였다.

• 한국전산구조공학회논문집
• /
• 제27권6호
• /
• pp.565-572
• /
• 2014

체계적으로 구축된 3차원 정보모델은 응용분야에서 효과적으로 활용 가능하다. 본 연구에서는 침수에 따른 피해정보 관리에 적합한 도시정보모델을 생성하여 활용하는 방법을 제시하였다. 정보의 상호운용성과 재사용성을 보장받기 위해 개방형 표준 데이터 스키마인 CityGML이 포함하고 있는 정보 항목을 활용하는 방법 및 추가 필요항목에 대한 확장방안을 제시하였고, 지형과 건물모델을 효과적으로 통합할 수 있는 방안을 제시하여 적용하였다. 실제 침수피해 사례를 대상으로 생성한 통합정보모델이 포함하고 있는 데이터를 활용하여 침수해에 따른 예상 사망자 수, 예상 고립자 수를 산정하였으며, 이를 통해 정보모델이 침수피해 산정과 같은 응용분야에 활용 가능함을 확인하였다.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2003년도 추계 학술발표회논문집
• /
• pp.271-279
• /
• 2003

The objective of this study is to evaluate the damage of the reinforced concrete bridge piers. For the purpose of this research, twelve reinforced concrete specimens were fabricated and experimented with quasi-static test method. The selected test parameters are lap splice, axial load ratio, confinement steel ratio and number of loading cycle. The method of evaluate of damage index is the model proposed by Park and Ang. In accordance with this research, the most effective test parameter is lap splice of longitudinal steel. Therefore, the retrofit scheme of reinforced concrete bridge piers with lap splice of longitudinal steel, which was constructed before 1992, must be settled without delay. Otherwise, the effect of axial force is trivial. The more confinement steel is less damage index and more loading cycle lead to raise damage. The damage statement proposed Park and Ang is the same with experimental results.

• 대한수의학회지
• /
• 제47권1호
• /
• pp.25-32
• /
• 2007

Houttuynia cordata root on non-lipid oxidative damage. The antioxidative efects of methanolic (MeOH) extract of Houttuynia cordata rooton non-lipid, including liposome oxidation, oxidation of deoxyribose, protein oxidation, chelating, scavenging,and 2'-deoxyguanosine (2'dG) oxidation were investigated. Houttuynia cordata root exhibited highantioxidative effect in a liposome model system. The inhibitory effect of MeOH extract on deoxyribosedamage exhibited antioxidative effect and it afforded considerable protection against damage to deoxyribose.In addition, MeOH extract at over 300extracts exhibited metal binding ability for hydrogen peroxide. Furthermore, the oxidation of 2'dG to 8-hydroxy-2-deoxyguanosine was inhibited by MeOH extracts, and scavenging activity for hydroxyl radicalexhibited a remarkable effect. The present results on biological model systems showed that MeOH extractswas effective in the protection of non-lipids against various oxidative model systems.

• 콘크리트학회논문집
• /
• 제17권6호
• /
• pp.1053-1064
• /
• 2005

The mechanical damage of concrete is normally attributed to the formation of microcracks and their propagation and coalescence into macroscopic cracks. This physical degradation is caused from progressive and hierarchical damage of the microstructure due to debonding and slip along bimaterial interfaces at the mesoscale. Their growth and coalescence leads to initiation of hairline discrete cracks at the mesoscale. Eventually, single or multiple major discrete cracks develop at the macroscale. In this paper, from this conceptual model of mechanical damage in concrete, the computational efforts were made in order to characterize physical cracks and how to quantify the damage of concrete materials within the laws of thermodynamics with the aid of interface element in traditional finite element methodology. One dimensional effective traction/jump constitutive interface law is introduced in order to accommodate the normal opening and tangential slips on the interfaces between different materials(adhesion) or similar materials(cohesion) in two and three dimensional problems. Mode I failure and mixed mode failure of various geometries and boundary conditions are discussed in the sense of crack propagation and their spent of fracture energy under monotonic displacement control.

• Steel and Composite Structures
• /
• 제14권4호
• /
• pp.367-377
• /
• 2013

Damage in structures often leads to failure. Thus it is very important to monitor structures for the occurrence of damage. When damage happens in a structure the consequence is a change in its modal parameters such as natural frequencies and mode shapes. Artificial Neural Networks (ANNs) are inspired by human biological neurons and have been applied for damage identification with varied success. Natural frequencies of a structure have a strong effect on damage and are applied as effective input parameters used to train the ANN in this study. The applicability of ANNs as a powerful tool for predicting the severity of damage in a model steel girder bridge is examined in this study. The data required for the ANNs which are in the form of natural frequencies were obtained from numerical modal analysis. By incorporating the training data, ANNs are capable of producing outputs in terms of damage severity using the first five natural frequencies. It has been demonstrated that an ANN trained only with natural frequency data can determine the severity of damage with a 6.8% error. The results shows that ANNs trained with numerically obtained samples have a strong potential for structural damage identification.

• Earthquakes and Structures
• /
• 제7권6호
• /
• pp.1045-1060
• /
• 2014

The 2011 off the Pacific coast of Tohoku Earthquake brought serious damage around the Tohoku district in Japan, and much human life and fortune were lost. Bridges were damaged by this earthquake. It was the most serious damage that the superstructures of bridges were flowed out by tsunami. Earthquakes of the same scale are predicted in other areas of Japan. It is necessary to take measures for bridges near coast. In order to understand the tsunami force acting on the bridge, hydraulic model experiments was conducted. In addition, this paper focused on fairing that is effective in wind resistant stability. Installing fairing to bridges has been verified by experiments whether it is possible to reduce the force of tsunami.

• Earthquakes and Structures
• /
• 제10권2호
• /
• pp.429-450
• /
• 2016

An attempt has been made to incorporate the concept of collapse safety margin into the procedures proposed in the performance-based earthquake engineering (PBEE) framework for direct earthquake loss estimation, in which the collapse probability curve obtained from incremental dynamic analysis (IDA) is mathematically characterized with the S-type fitting model. The regressive collapse probability curve is then used to identify non-collapse cases and collapse cases. With the assumed lognormal probability distribution for non-collapse damage indexes, the expected direct earthquake loss ratio is calculated from the weighted average over several damage states for non-collapse cases. Collapse safety margin is shown to be strongly related with sustained damage endurance of structures. Such endurance exhibits a strong link with expected direct earthquake loss. The results from the case study on three concrete frames indicate that increase in cross section cannot always achieve a more desirable output of collapse safety margin and less direct earthquake loss. It is a more effective way to acquire wider collapse safety margin and less direct earthquake loss through proper enhancement of reinforcement in structural components. Interestingly, total expected direct earthquake loss ratio seems to be insensitive a change in cross section. It has demonstrated a consistent correlation with collapse safety margin. The results also indicates that, if direct economic loss is seriously concerned, it is of much significance to reduce the probability of occurrence of moderate and even severe damage, as well as the probability of structural collapse.

• 복합신소재구조학회 논문집
• /
• 제5권2호
• /
• pp.27-32
• /
• 2014

Since the collapse of historical masonry structures in Europe in the late 1990's, the interests in understanding the long-term effect of masonry under sustained compressive stresses have increased. That requires combining the significance of time-dependent effects of creep with the effect of damage due to overstress to realize the evolution of cracks and then failure in masonry. Meanwhile, composite analysis of masonry columns was proven effective for realizing ultimate strength capacity of masonry column. In this study, a simplified mechanical model with step-by-step in time analysis was proposed to incorporate the interaction of damage and creep to estimate the maximum stress occurred in masonry. It was examined that the interaction of creep and damage in masonry can accelerate the failure of masonry.