• Structural Engineering and Mechanics
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• v.9 no.2
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• pp.195-208
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• 2000

To confirm the theory and static defect energy (SDE) equations proposed in the first part, extensive numerical simulation studies are performed in this portion. Stiffness method is applied to calculate the components of the stresses and strains from which the energy components and finally, the SDE are obtained. Examples are designed to cover almost all kinds of possibilities. Variables include structural type, material, cross-section, support constraint, loading type, magnitude and position. The SDE diagram is unique in the way of presenting damage information: two different energy constants are separated by a sharp vertical drop right at the damage location. Simulation results are successfully implemented for both methods in all the cases.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.4
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• pp.71-80
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• 2007

The purpose of this study is to suggest the criteria for the damaged mountainous landscape based on the shape, location and ratio of damaged landscape. For the study, the preference and landscape adjectives were analyzed on visual images and simulations. The variables for analysis were the amount of the damaged ratio(10%, 30%, 50%), the location of the damage (upper, middle, lower) and the various forms of the damage(spot, line, area). According to the results of this study, in accordance with the amount of damage, the visual preference recorded its lowest with the a rate of 50%. As for the location of the damage, the lower-ridge of the mountain showed the highest preference, and the upper-ridge was recorded as the lowest. The linear damage type showed the highest preference. On the other hand, the spotted damage type showed lowest. The results indicate that the visual preference increases when there is a lower ratio of damage, as the damage locates at the lower-ridge, and also when there is a presence of linear formation development. The group of linear formation-the lower ridge-10% showed the highest preference, and the group of linear formation-the mid ridge-50% was the lowest with the results of 3-way ANOVA. The group of linear formation-lower ridge-10% in particular had virtually no differences of visual preference when it was compared with the original scene. The damage with the spotted formation, on the mid-upper location and the high ratio of damage were analyzed as factors that give negative influence on the mountainous landscape. The main features of mountainous landscape were reduced into two factors, 'total estimation' and 'spatial scale' by the factor analysis with total variance of 65.96%.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.1
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• pp.95-111
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• 1998

In this study, the concepts and procedures of the seismic damage analysis methods are examined for both the element-level and the system-level. The seismic damage analysis at the element-level is performed for several example structures using existing method for structural elements or single-degree-of-freedom (SDOF) systems such as the Park and Ang method. In order to analyze seismic damage at the system-level, two types of procedures are used. In the first type of procedure, the system-level seismic responses can be estimated by using the system representative response method(SRRM), or the equivalent SDOF system response method (ESDOF-SRM). Then, the system-level seismic damage is analyzed from the system-level seismic responses using existing method for structural elements or SDOF systems. IN the second type of procedure, the system-level seismic damages are analyzed using the element damage combination method (EDCM) combing the element-level damage indices determined by existing method. To compare tendency of the seismic damage analysis using each methods, example analysis is accomplished for several cases of different structures and different earthquake excitation.

• Structural Engineering and Mechanics
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• v.40 no.5
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• pp.719-743
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• 2011

A hybrid damage monitoring scheme using parallel acceleration-impedance approaches is proposed to detect girder damage and support damage in steel plate-girder bridges which are under ambient train-induced excitations. The hybrid scheme consists of three phases: global and local damage monitoring in parallel manner, damage occurrence alarming and local damage identification, and detailed damage estimation. In the first phase, damage occurrence in a structure is globally monitored by changes in vibration features and, at the same moment, damage occurrence in local critical members is monitored by changes in impedance features. In the second phase, the occurrence of damage is alarmed and the type of damage is locally identified by recognizing patterns of vibration and impedance features. In the final phase, the location and severity of the locally identified damage are estimated by using modal strain energy-based damage index methods. The feasibility of the proposed scheme is evaluated on a steel plate-girder bridge model which was experimentally tested under model train-induced excitations. Acceleration responses and electro-mechanical impedance signatures were measured for several damage scenarios of girder damage and support damage.

• Journal of the Korean Geosynthetics Society
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• v.23 no.2
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• pp.29-42
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• 2024

The 2017 Pohang earthquake caused damage to quay structures due to liquefaction. Liquefaction occurs when effective stress is lost due to an increase in excess pore water pressure during an earthquake. As a result, the damage caused to the pier-type quay wall was identified and the damage caused by liquefaction was analyzed. In addition, in the case of improved ground, damage occurred due to liquefaction of the lower sand layer due to the difference in stiffness from the soft rock layer, so additional numerical analysis was performed assuming non-liquefaction ground. There are several factors that affect the increase in excess pore water pressure ratio, such as the relative density of the ground and the magnitude of the input seismic acceleration. Therefore, this study performed numerical analysis for Cases 1 to 3 by increasing the magnitude of the input acceleration, and in the case of improved ground, damage occurred due to liquefaction of the lower sand layer, so the analysis was performed assuming non-liquefaction ground. As a result, the improved ground requires additional reinforcement when there is liquefied ground below, and the horizontal displacement of the pier-type quay piles was reduced by about two times.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.99-102
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• 2023

In this paper, the system is proposed and implemented to share the part number, the part name, and the vehicle type through the improvement sharing bulletin board for automobile repair and maintenance. And when photos of damage parts are uploaded to the system, the system analyzes it using a deep learning model to analyze whether it is damaged and automatically classify the type of damage. By providing repair and maintenance quotes for a significant part, the system provides economically repaired by providing comparative adjustment information on repair costs to drivers who are particularly concerned about the market prices of parts and maintenance services. Through the existing bulletin board, you can exchange and share information about parts by sharing various information on repair and maintenance. This paper provides in detail the average market price per type of damage during automobile repair and maintenance, helping drivers who do not know the details of parts and maintenance services to receive reasonable quotes by providing price information.

• Molecules and Cells
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• v.19 no.2
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• pp.167-179
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• 2005

The cells of metazoans respond to DNA damage by either arresting their cell cycle in order to repair the DNA, or by undergoing apoptosis. This response is highly conserved across species, and many of the genes involved in this DNA damage response have been shown to be inactivated in human cancers. This suggests the importance of DNA damage response with regard to the prevention of cancer. The DNA damage checkpoint responses vary greatly depending on the developmental context, cell type, gene expression profile, and the degree and nature of the DNA lesions. More valuable information can be obtained from studies utilizing whole organisms in which the molecular basis of development has been well established, such as Drosophila. Since the discovery of the Drosophila p53 orthologue, various aspects of DNA damage responses have been studied in Drosophila. In this review, I will summarize the current knowledge on the DNA damage checkpoint response in Drosophila. With the ease of genetic, cellular, and cytological approaches, Drosophila will become an increasingly valuable model organism for the study of mechanisms inherent to cancer formation associated with defects in the DNA damage pathway.

• Structural Engineering and Mechanics
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• v.38 no.1
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• pp.81-97
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• 2011

In this research, the wavelet transform is used to analyze time response of a cracked beam carrying moving mass for damage detection. In this respect, a new damage detection method based on the combined use of continuous and discrete wavelet transforms is proposed. It is shown that this method is more capable in making damage signature evident than the traditional two approaches based on direct investigation of the wavelet coefficients of structural response. By the proposed method, it is concluded that strain data outperforms displacement data at the same point in revealing damage signature. In addition, influence of moving mass-induced terms such as gravitational, Coriolis, centrifuge forces, and pure inertia force along the deflection direction to damage detection is investigated on a sample case. From this analysis it is concluded that centrifuge force has the most influence on making both displacement and strain data damage-sensitive. The Coriolis effect is the second to improve the damage-sensitivity of data. However, its impact is considerably less than the former. The rest, on the other hand, are observed to be insufficient alone.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.3
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• pp.272-278
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• 2010

A method for damage detection in a plate structure is presented based on strain waves that are generated by impact or damage in the structure. Strain responses from continuous sensors, which are long ribbon-like sensors made from piezoceramic fibers or other materials, were used with a neural network technique to estimate the damage location. The continuous sensor uses only a small number of channels of data acquisition and can cover large areas of the structure. A grid type structural neural system composed of the continuous sensors was developed for effective damage localization in a plate structure. The ratios of maximum strains and arrival times of the maximum strains obtained from the continuous sensors were used as input data to a neural network. Simulated damage localizations on a plate were carried out and the identified damage locations agreed reasonably well with the exact damage locations.

• Geomechanics and Engineering
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• v.38 no.1
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• pp.57-68
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• 2024

Tunnels offer myriad benefits for modern countries, and understanding their behavior under loads is critical. This paper analyzes and evaluates the damage to buried horseshoe tunnels under soil pressure and traffic loading. To achieve this, a numerical model of this type of tunnel is first created using ABAQUS software. Then, fracture mechanics theory is applied to investigate the fracture and damage of the horseshoe tunnel. The numerical analysis is based on the damage plasticity model of concrete, which describes the inelastic behavior of concrete in tension and compression. In addition, the reinforcing steel is modeled using the bilinear plasticity model. Damage contours, stress contours, and maximum displacements illustrate how and where traffic loading alters the response of the horseshoe tunnel. Based on the results, the fracture mechanism proceeded as follows: initially, damage started at the center of the tunnel bottom, followed by the formation of damage and micro-cracks at the corners of the tunnel. Eventually, the damage reached the top of the concrete arch with increasing loading. Therefore, in the design of this tunnel, these critical areas should be reinforced more to prevent cracking.