• Smart Structures and Systems
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• v.14 no.3
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• pp.469-477
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• 2014

As a kind of intelligent materials, conductive asphalt concrete has a broad application prospect including melting ice and snow on the pavement, closing cracks in asphalt concrete, sensing pavement damage, and so on. Conductive pavement will be suffered from fatigue failure as conventional pavement in the process of service, and this fatigue damage of internal structure can be induced by electrical signal output. The characteristics of electrical signal variation of conductive asphalt concrete in the process of fatigue cracking were researched in this paper. The whole process was clearly divided into three stages according to resistance changes, and the development of fatigue damage wasn't obvious in stage I and stage II, while in stage III, the synchronicity between the resistance and damage began to appear. Thus, fatigue damage variable D and initial damage value $D_0$ represented by the functions of resistance were introduced in stage III. After calculating the initial damage value $D_0$ under different stress levels, it was concluded that the initial damage value $D_0$ had no noticeable change, just ranged between 0.24 and 0.25. This value represented a critical point which could be used to inform the repair time of early fatigue damage in the conductive asphalt pavement.

• Journal of Environmental Science International
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• v.31 no.1
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• pp.87-97
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• 2022

In this study, type analysis was conducted along with the advancement of basic data to calculate the maximum damage caused by strong winds during the typhoon period. The result of the damage by region showed that in 2012, the difference in damage was clearly distinguished as the region was classified in detail. In addition, the result of the annual damage in 2011 was strong on the west coast, and in 2016, the damage to the southeast coast was significant. In 2012, the 3-second gust was relatively stronger on the west and southeast coasts than in 2011, and the winds blew stronger along the southeast coast in 2016. Monthly damage data showed that the damage to the west coast was high in August, and the damage to the southeast coast was high in October from 2002 to 2019. The 3-second gust showed the result of wide expansion throughout the southern coast of the Korean Peninsula in October. As a result, the damage differs for type bacause the intensities and paths of typhoons vary depending on their characteristics, the 3-second gust blows differently by region based on regional characteristics, and the sale price is considered in metropolitan cities.

• Geomechanics and Engineering
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• v.37 no.2
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• pp.149-166
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• 2024

The acoustic emission (AE) technique is utilized to estimate the rock failure status in underground spaces. Understanding the AE characteristics under loading conditions is essential to ensure the reliability of AE monitoring. The AE characteristics depend on the material properties (p-wave velocity, density, UCS, and Young's modulus) and damage stages (stress ratio) of the target rock mass. In this study, two groups of granite specimens (based on the p-wave velocity regime) were prepared to explore the effect of material properties on AE characteristics. Uniaxial compressive loading tests with an AE measurement system were performed to investigate the effect of the rock properties using AE indices (count index, energy index, and amplitude index). The test results were analyzed according to three damage stages classified by the stress ratio of the specimens. Count index was determined to be the most suitable AE index for evaluating rock mass stability.

• Computers and Concrete
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• v.19 no.5
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• pp.501-507
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• 2017

The predictive utility of a damage model depends heavily on its particular choice of a damage variable, which serves as a macroscopic approximation in describing the underlying micromechanical processes of microdefects. In the case of spatially perfectly randomly distributed microcracks or microvoids in all directions, isotropic damage model is an appropriate choice, and scalar damage variables were widely used for isotropic or one-dimensional phenomenological damage models. The simplicity of a scalar damage representation is indeed very attractive. However, a scalar damage model is of somewhat limited use in practice. In order to entirely characterize the isotropic damage behaviors of damaged materials in multidimensional space, a system theory of isotropic double scalar damage variables, including the expressions of specific damage energy release rate, the coupled constitutive equations corresponding to damage, the conditions of admissibility for two scalar damage effective tensors within the framework of the thermodynamics of irreversible processes, was provided and analyzed in this study. Compared with the former studies, the theoretical formulations of double scalar damage variables in this study are given in the form of matrix, which has many features such as simpleness, directness, convenience and programmable characteristics. It is worth mentioning that the above-mentioned theoretical formulations are only logically reasonable. Owing to the limitations of time, conditions, funds, etc. they should be subject to multifaceted experiments before their innovative significance can be fully verified. The current level of research can be regarded as an exploratory attempt in this field.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.352-361
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• 2003

A fatigue damage accumulation model based on the continuum damage mechanics theory was develope(1 where modules decay ratios in tension and shear on used as indicators for damage variables D . In the model, the damage variables are considered to be second-order tensors. Then the maximum principal damage variable, $D^*$ is introduced According to the similarity to the Principal stress, $D^*$ is obtained as the maximum eigen value of damage tensor [D']. Under proportional tension and torsion loadings, fatigue lives were satisfactorily predicted at any combined stress ratios using the present model in which the fatigue characteristics only under uniaxial tension and pure torsion loadings on needed. Fatigue life prediction under uniaxial tension and pure torsion loadings, was performed based on the damage mechanics using boundary element method.

• Geomechanics and Engineering
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• v.12 no.2
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• pp.269-294
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• 2017

This study aimed to realize the creation of fuzzy stochastic damage to describe reliability more essentially with the analysis of harmony of damage conception, probability and fuzzy degree of membership in interval [0,1]. Two kinds of fuzzy behaviors of damage development were deduced. Fuzzy stochastic damage models were established based on the fuzzy memberships functional and equivalent normalization theory. Fuzzy stochastic damage finite element method was developed as the approach to reliability simulation. The three-dimensional fuzzy stochastic damage mechanical behaviors of Jianshan mine slope were analyzed and examined based on this approach. The comprehensive results, including the displacement, stress, damage and their stochastic characteristics, indicate consistently that the failure foci of Jianshan mine slope are the slope-cutting areas where, with the maximal failure probability 40%, the hazardous Domino effects will motivate the neighboring rock bodies' sliding activities.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.805-812
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• 2002

The number of old concrete structure which needs to be strengthened has been increased. The repair and strengthening methods have to be determined based on the current status of the structure. Consequently the estimation method for the damage status of the structure has been desperately needed, but no studies have been tried to use the crack and deflection characteristics to estimate the damage status. In this study, the crack characteristics depending on load level were measured and analysed. The crack characteristics observed from 11 samples were compared with damage status, and load level, The crack characteristics examined in this study include crack number, crack length, crack range, crack interval, maximum crack length, crack area, and average crack length. The deflections were normalized based on yield deflection, and the relationship between the relative deflection and the standardized crack characteristics were compared. Among the crack characteristics, crack interval, crack area, crack range, and maximum crack length, have been showed a close relationship to the relative deflection. Therefore, if such crack characteristics are evaluated, the maximum load applied to the structure is believed to be estimated. if additional parameters such as size of specimen, strength of concrete and steel, and steel ratio are studied, the damage status of structure can be estimated more accurately.

• Journal of Digital Convergence
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• v.22 no.1
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• pp.23-32
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• 2024

This study selected in-depth discharge damage survey data and analyzed 92,364 patients whose main diagnosis was S00-T98 (damage, addiction, and specific other results due to external factors) based on the Korean Standard Classification of Diseases and Deaths (KCD-7th) among patients discharged from the hospital after inpatient treatment from January 2016 to December 2018. As a result of analyzing the general characteristics of injured and traumatic patients, the incidence rate of men was higher in gender, and the incidence rate of women increased as the year increased. As a result of analyzing the characteristics of injury and trauma patients other than injury, the injury intention had a high rate of unintentional damage, the damage place was the highest on the road/road, and it showed a decreasing trend as the year increased, and it showed an increasing trend in the residential area. It can be used as basic data for the establishment of a related system to prevent damage as a result of subsang.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.87-92
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• 2009

It has been considered only with the concerned regional damage costs whenever the restoration and flood control measures were established in Korea. If the relationship between regional flood frequency and damages is quantitatively analyzed, more resonable and reliable countermeasure for flood protection and restoration can be proposed. Historical data ('70~'07) about flood damage in Korea were utilized and analyzed to present such relationship using the point frequency analysis. Also, the quadrant analysis was employed to divide into 4 categories: high frequency-high damage, high frequency-low damage, low frequency-high damage, and low frequency-low damage. If the results from this study were utilized well in specific cities and counties in Korea, it would be helpful to establish the countermeasures and action plans for flood protection because it was possible to compare with the relationship between flood frequency and damage of each region. And it would be the fundamental data for estimating the effect of future flood protection plan.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.99-99
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• 2020

The frequency and scale of domestic flood damage continues to increase, but the criteria for responding to flood damage have not been established. To this end, research is underway to estimate the amount of rainfall in each region so that it can be used to respond to flood damage. The limit rainfall is defined as the cumulative maximum rainfall for each duration that causes flooding, and this research purpose to improve the threshold rainfall by estimating the damage based on the damage history in units of 5 years and analyzing changes over time. The limit rainfall based on the damage history was estimated by using the NDMS past damage history of the Ministry of the Interior and Safety and the rainfall minutes data of AWS and ASOS. The period for estimating the limit rainfall is 2013 ~ 2017, 2015 ~ 2019, and the limit rainfall is estimated by analyzing the relationship between the flood damage history and the rainfall event in each period. Considering changes in watershed characteristics and disaster prevention performance, the data were compared using 5-year data. As a result of the analysis, the limit rainfall based on the damage history could be estimated for less than about 10.0% of the administrative dongs nationwide. As a result of comparing the limit rainfall by period, it was confirmed that the area where the limit rainfall has increased or decreased This was analyzed as a change due to rainfall events or urbanization, and it is judged that it will be possible to improve the risk criteria of flooding.