• Computers and Concrete
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• v.2 no.4
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• pp.325-343
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• 2005

Chloride ingress is a common cause of deterioration of reinforced concrete located in coastal zone. Modeling the chloride ingress is an important basis for designing reinforced concrete structures and for assessing the reliability of an existing structure. The modeling is also needed for predicting the deterioration of a reinforced structure. The existing deterministic solution for prediction model of corrosion initiation cannot reflect uncertainties which input variables have. This paper presents an approach to the fuzzy arithmetic based modeling of the chloride-induced corrosion of reinforcement in concrete structures that takes into account the uncertainties in the physical models of chloride penetration into concrete and corrosion of steel reinforcement, as well as the uncertainties in the governing parameters, including concrete diffusivity, concrete cover depth, surface chloride concentration and critical chloride level for corrosion initiation. There are a lot of prediction model for predicting the time of reinforcement corrosion of structures exposed to chloride-induced corrosion environment. In this work, RILEM model formula and Crank's solution of Fick's second law of diffusion is used. The parameters of the models are regarded as fuzzy numbers with proper membership function adapted to statistical data of the governing parameters instead of random variables of probabilistic modeling of Monte Carlo Simulation and the fuzziness of the time to corrosion initiation is determined by the fuzzy arithmetic of interval arithmetic and extension principle. An analysis is implemented by comparing deterministic calculation with fuzzy arithmetic for above two prediction models.

• Structural Engineering and Mechanics
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• v.26 no.5
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• pp.569-589
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• 2007

This paper presents an analytical model for RC beam-column connections that takes into account bond deterioration between reinforcing steel and concrete. The model is based on the Lumped Damage Mechanics (LDM) theory which allows for the characterization of cracking, degradation and yielding, and is extended in this paper by the inclusion of the slip effect as observed in those connections. Slip is assumed to be lumped at inelastic hinges. Thus, the concept of "slip hinge", based on the Coulomb friction plasticity theory, is formulated. The influence of cracking on the slip behavior is taken into account by using two concepts of LDM: the effective moment on an inelastic hinge and the strain equivalence hypothesis. The model is particularly suitable for wide beam-column connections for which bond deterioration dominates the hysteretic response. The model was evaluated by the numerical simulation of five tests reported in the literature. It is found that the model reproduces closely the observed behavior.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.244-249
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• 2014

In this research, it have developed a sensor that could diagnose inner deterioration of covered wires. With this sensor it observed results from simulation, and the attribute required for realization. For simulation it have used FLUX, it have considered all of geometric and electromagnetic information from coil and base metal that influences eddy current sensor's property in order to predict the final result. It assumed there is no mutual inductance in the coil with N number of turns, because equivalent current flows in coil that is continuously connected in eddy current sensor. It assumed circular coil loop draws a circle, always have self inductance, and they are connected in series and overlapped according number of turns (N) in coil, and bobbin configuration. Actual sensor was produced with consideration of inductance and number of turns (N). In conclusion, it were able to test the dependency through results from simulation, actual measurement, and modeling of simulation. It is considered that attributes of respective base metal and structure can be predicted by simulating in advance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.159-167
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• 2003

Cracks in reinforced concrete structures reduce overall durability by allowing the penetration of water and aggressive agents, thereby accelerating the deterioration of the reinforcing steel. Highway pavement and bridge decks are especially susceptible to this type of deterioration since these structures exhibit high rates of shrinkage and are frequently exposed to aggressive environmental conditions. The objectives of this investigation included the development of experimental procedures for assessing shrinkage cracking potential of recycled aggregate concrete, the evaluation of mix composition on shrinkage cracking potential, and the development of theoretical models to simulate early-age cracking behavior. Specifically, the influences of shrinkage-reducing admixture(SRA) and recycled aggregate concrete were investigated. The shrinkage-reducing admixture substantially reduces free shrinkage and restrains shrinkage cracking while providing similar mechanical properties. A fracture mechanics modeling approach was developed to predict the behavior of a variety of restrained concrete specimens. This modeling approach was used to successfully explain experimental results from a variety of mixture compositions. The model was used to demonstrate the influence of material and structural properties on the potential for cracking.

• Earthquakes and Structures
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• v.3 no.5
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• pp.649-673
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• 2012

Recent studies have highlighted the importance of accounting for aging and deterioration of bridges when estimating their seismic vulnerability. Effects of structural degradation of multiple bridge components, variations in bridge geometry, and comparison of different environmental exposure conditions have traditionally been ignored in the development of seismic fragility curves for aging concrete highway bridges. This study focuses on the degradation of multiple bridge components of a geometrically varying bridge class, as opposed to a single bridge sample, to arrive at time-dependent seismic bridge fragility curves. The effects of different exposure conditions are also explored to assess the impact of severity of the environment on bridge seismic vulnerability. The proposed methodology is demonstrated on a representative class of aging multi-span reinforced concrete girder bridges typical of the Central and Southeastern United States. The results reveal the importance of considering multiple deterioration mechanisms, including the significance of degrading elastomeric bearings along with the corroding reinforced concrete columns, in fragility modeling of aging bridge classes. Additionally, assessment of the relative severity of exposure to marine atmospheric, marine sea-splash and deicing salts, and shows 5%, 9% and 44% reduction, respectively, in the median value bridge fragility for the complete damage state relative to the as-built pristine structure.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1710-1712
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• 1996

This paper was practiced insulation failure test forcing to accelerate on frequency of 420 HZ. There was manufactured generator stator windings for 500MVA thermal plants and selected accelerating deterioration voltage of 5.5kV/mm for electrical aging. Moreover, so as to verification of this experiments, we carried out modeling analysis due to finite element method using to ANSYS5.0 program for common package and imitated multi-stress aging for analyzing electrical and mechanical stress distribution.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.285-286
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• 2021

These days, interior construction is performed to prevent the deterioration of old building finishings or to make distinctive designs. In case of interior construction, a construction cost is estimated through basic 2D drawings in the design step. Accordingly, an efficient construction plan and direction is established according to budget. In such a case, construction is dependent on 2D drawings. At that time, a risk can occur easily. This study is aimed at reducing the cost and risk of interior construction by implementing 3D drawings with the use of the visual data of 2D drawings. For accurate analysis, 2D drawings were completed, and then 3D interior construction modeling for various buildings was conducted with the 3D modeling software 3D Max. According to the 3D modeling, it reduced the cost and risk more than 2D drawings based design, and influenced the improvement in the understanding of orderers and workers.

• Earthquakes and Structures
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• v.3 no.1
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• pp.83-95
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• 2012

Seismic damage and vulnerability of five historical masonry structures surveyed after the 1999 Kocaeli and Duzce, Turkey earthquakes are discussed in this paper. The structures are located in two neighboring cities that have been struck by five very large ($M_s{\geq}7.0$) earthquakes during the $20^{th}$ century alone. Older masonry mosques with arches and domes and their masonry minarets (slender towers) were among the most affected structures in this highly seismic region. While some of the religious and historical structures had virtually no damage, most structures suffered significant damage or collapsed. In the city of Bolu, for example, approximately 600-year-old Imaret, 500-year-old Kadi, 250-year-old Sarachane, and 100-year-old Yildirim Bayezid mosques suffered substantial structural damage after the 1999 earthquakes. Another historical mosque surveyed in Duzce partially collapsed. Most common factors contributing to deterioration of historical structures are also presented. Furthermore, a brief overview of issues associated with analysis and modeling of historical masonry structures is provided.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.481-484
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• 2001

High voltage induction motors are widely used in industrial factory because have many benefits. But the insulated materials of induction motor are aged by using time, electrical, thermal, circumstantial stresses and so on. Motor failures are occurred by these deterioration phenomena and give rise economic problems to user. In many motor failures, insulated material problems of stator winding happen frequently and occupy high percentages in the failure source. In this paper, the testing specimen(motorette) is manufactured by modeling of stator winding of high voltage induction motor and accelerating test is carried out. Partial discharge signals detected by RF sensor are used to analyze deterioration condition of stator windings. According to aging time, the 3D ( ${\Phi}$-Q-N) distribution and skewness of partial discharge signals are changed.

• The KSFM Journal of Fluid Machinery
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• v.10 no.3 s.42
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• pp.9-16
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• 2007

Deterioration of surface of turbomachinery blades occurs in course of time due to many factors and hence reduces the performance of the machine. In this paper, the effects of surface roughness of transonic axial compressor blade on performance are studied considering a reference blade and a shape distorted (optimized) blade. Optimal blade is designed considering sweep and lean. Baldwin-Lomax turbulence model is used for flow field analysis and Cebeci-Smith roughness model is formulated for roughness modeling. It is found that, as the surface roughness increases, adiabatic efficiency, total temperature ratio and total pressure ratio decrease while Mach number increases. Performance deterioration is more severe in case of distorted blade as compared to reference blade.