• Smart Structures and Systems
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• v.24 no.2
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• pp.233-242
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• 2019

In this paper, an inverse approach based on uniform load surface (ULS) is presented for structural damage localization and quantification. The ULS is excellent approximation for deformed configuration of a structure under distributed unit force applied on all degrees of freedom. The ULS make use of natural frequencies and mode shapes of structure and in mathematical point of view is a weighted average of mode shapes. An objective function presented to damage detection is discrepancy between the ULS of monitored structure and numerical model of structure. Solving this objective function to find minimum value yields damage's parameters detection. The teaching-learning based optimization algorithm has been employed to solve inverse problem. The efficiency of present damage detection method is demonstrated through three numerical examples. By comparison between proposed objective function and another objective function which make use of natural frequencies and mode shapes, it is revealed present objective function have faster convergence and is more sensitive to damage. The method has good robustness against measurement noise and could detect damage by using the first few mode shapes. The results indicate that the proposed method is reliable technique to damage detection in structures.

• Journal of Korea Water Resources Association
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• v.42 no.1
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• pp.51-60
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• 2009

2/3 of the Imjin River Basin area is located in North Korea, so it was hard to acquire reliable rainfall and hydrological information. This point is one of the factors that has added to flood damage. In this study, flood runoff for the river basin was simulated using hydrological radar, which is installed in an effort to reduce flood damage in the Imjin River Basin, which habitually suffers from flood damage. The feasibility of the distributed flood model was reviewed for the river basin, which is lacking in hydrological data such as rainfall and recent soil data. Based on the hydrograph, observed value was not consistent partially because of insufficient data, but peak discharge and the overall pattern showed relatively precise runoff results which can be applied in actual work.

• Smart Structures and Systems
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• v.1 no.1
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• pp.29-46
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• 2005

In this study, a wavelet packet based method is proposed for identifying damage occurrence and damage location for beam-like structures. This method assumes that the displacement or the acceleration response time histories at various locations along a beam-like structure both before and after damage are available for damage assessment. These responses are processed through a proper level of wavelet packet decomposition. The wavelet packet signature (WPS) that consists of wavelet packet component signal energies is calculated. The change of the WPS curvature between the baseline state and the current state is then used to identify the locations of possible damage in the structure. Two numerical studies, one on a 15-storey shear-beam building frame and another on a simply-supported steel beam, and an experimental study on a simply-supported reinforced concrete beam are performed to validate the proposed method. Results show the WPS curvature change can be used to locate both single and sparsely-distributed multiple damages that exist in the structure. Also the accuracy of assessment does not seem to be affected by the presence of 20-15dB measurement noise. One advantage of the proposed method is that it does not require any mathematical model for the structure being monitored and hence can potentially be used for practical application.

• Smart Structures and Systems
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• v.3 no.4
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• pp.475-494
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• 2007

This paper deals with the development of an innovative distributed construction system based on smart prefabricated concrete elements for the real-time condition assessment of civil infrastructure. So far, two reduced-scale prototypes have been produced, each consisting of a $0.2{\times}0.3{\times}5.6$ m RC beam specifically designed for permanent instrumentation with 8 long-gauge Fiber Optic Sensors (FOS) at the lower edge. The sensing system is Fiber Bragg Grating (FBG)-based and can measure finite displacements both static and dynamic with a sample frequency of 625 Hz per channel. The performance of the system underwent validation in the laboratory. The scope of the experiment was to correlate changes in the dynamic response of the beams with different damage scenarios, using a direct modal strain approach. Each specimen was dynamically characterized in the undamaged state and in various damage conditions, simulating different cracking levels and recurrent deterioration scenarios, including cover spalling and corrosion of the reinforcement. The location and the extent of damage are evaluated by calculating damage indices which take account of changes in frequency and in strain-mode-shapes. The outcomes of the experiment demonstrate how the damage distribution detected by the system is fully compatible with the damage extent appraised by inspection.

• The Journal of Fisheries Business Administration
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• v.49 no.4
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• pp.83-97
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• 2018

The ocean is very important to mankind for its infinite value in resource storage and utilization. In shallow coastal waters, landfill as well as pollution damage occurs frequently for the promotion of important public and private projects that are the driving forces of national development. In this case, compensation paid for the loss or damage of fishing rights acquired by the fishing community shall be distributed to each individual of the fishing community in accordance with the appropriate balance. In reality, as fishing communities in different sectors coexist, the voting rights of the general meeting of fishing communities are ignored as a minority, and the demand for the rights is ignored by the majority. Many other industries receive fish compensation, even though they have not suffered much damage. As a result serious conflicts between the individuals of the fishing community have caused social problems. Therefore, similar cases are investigated and analyzed to provide a reasonable solution.

• Journal of Sasang Constitutional Medicine
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• v.12 no.2
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• pp.171-183
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• 2000

1. Back ground and purpose An experimental study has done to examine the effect of defense and cure gastric mucasal damage of Mokdan-pijihwang-tang. 2. Methods Mice had intragastric injected with MJ extract before indomethacin treatment which induces homorrhage infarct and erosion artificially. Degree of lipid peroxidation, general morphology, change of mucous cell, the distribution of PNA, ICAM and distribution of apoptotic cell were objected. (Abbreviation) MJ : Mokdanpijihwang-tang, PNA : Peanut Agglutinin, ICAM : Intercellular Adhesion Molecule 3 Results 1) The degree of lipid peroxidation in INDO-group had increased conspicuously than control group. But the degree of lipid peroxidation in MJ-group had decreased than INDO-group and these decline had probability. 2) After indomethacin treatment, hemorrhage infarct and erosion had increased in stomach body. But in MJ-group, the configuration is normal, except the group intragastric injected with MJ extract at hour 24 before indomethacin treatment. 3) Surface mucous cell and neck mucous had disappeared in INDO-group. But in MJ-group tormal distribution had shown like control group except the group intragastric injected with MJ extract at hour 24 before indomethacin treatment. 4) PNA positive reaction had not shown in INDO-group. But medium PNA positive reaction had shown In Mj-group. 5) ICAM positive reacted cell had shown in INDO-group. The decrease of ICAM positive cell were shown than INDO-group. 6) A number of apoptotic cell was distributed in hemorrhagic erosion. A few number of apoptotic cell was distributed in MJ-group except some surface mucous. 4. Conclusion These results suggest that MJ has an effect on cure of gastric mucosal damage.

• Smart Structures and Systems
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• v.16 no.1
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• pp.223-242
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• 2015

Wireless sensor networks (WSNs) have emerged as a novel solution to many of the challenges of structural health monitoring (SHM) in civil engineering structures. While research projects using WSNs are ongoing worldwide, implementations of WSNs on full-scale structures are limited. In this study, a WSN is deployed on a full-scale 17.3m-long, 11-bay highway sign support structure to investigate the ability to use vibration response data to detect damage induced in the structure. A multi-level damage detection strategy is employed for this structure: the Angle-between-String-and-Horizon (ASH) flexibility-based algorithm as the Level I and the Axial Strain (AS) flexibility-based algorithm as the Level II. For the proposed multi-level damage detection strategy, a coarse resolution Level I damage detection will be conducted first to detect the damaged region(s). Subsequently, a fine resolution Level II damage detection will be conducted in the damaged region(s) to locate the damaged element(s). Several damage cases are created on the full-scale highway sign support structure to validate the multi-level detection strategy. The multi-level damage detection strategy is shown to be successful in detecting damage in the structure in these cases.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.2
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• pp.355-370
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• 2014

Cooperative spectrum sensing has been considered as a promising approach to improve the sensing performance in distributed cognitive radio networks. However, there may exist some selfish secondary users (SUs) who are unwilling to cooperate. The presence of selfish SUs could cause catastrophic damage to the performance of cooperative spectrum sensing. Following the social perspective, we propose a Social Tie-based Incentive Scheme (STIS) to deal with the selfish problem for cooperative spectrum sensing in distributed cognitive radio networks. This scheme inspires SUs to contribute sensing information for the SUs who have social tie but not others, and such willingness varies with the strength of social tie value. The evaluation of each SU's social tie derives from its contribution for others. Finally, simulation results validate the effectiveness of the proposed scheme.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.898-904
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• 2013

In order to minimize the damage from power outage, power system should be restored quickly. In this paper, a procedure for the restoration of microgrid is proposed. After elimination of the causes of power outage, a black start algorithm is executed by considering the characteristics of distributed generation control. After all resources have been recovered to the normal state, a grid reconnecting algorithm for stable operation in grid-connected mode is performed. In order to verify the proposed algorithm, low voltage microgrid is simulated using PSCAD/EMTDC.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.997-999
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• 1998

An operationally secure power system is one low probability of blackout or equipment damage. The power system is needed to maintain a designated security level at minimum operating cost. The inclusions of security make power system problem complex. But, because security and optimality are normally conflicting requirement, the separate treatments of both are inappropriate. So, a unified hierarchical formulation is needed. In this paper, the overview of security constrained optimal power flow (SCOPF) is presented and an introduction of parallel distributed formulation to SCOPF is also presented.