• Journal of Korean Society of Steel Construction
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• v.22 no.1
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• pp.13-20
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• 2010

Seismic risk assessment of railway bridges is an important issue for a transportation network, because loss of functionality of railway bridges could result in severe disruption of the railway line, as no redundant routing systems generally exist. Although many studies have been conducted by numerous researchers regarding fragility analyses of bridge structure, little or no studies have been done for fragility analyses of a class of bridge structures considering their geometric variability. This study performs a fragility analysis for Track-on Steel-Plate-Girder (TOSPG) railway bridges in Korea considering their span variability. Seismic fragility curves are developed for a series of bridges with different spans varying from 2 to 15. At last, the fragility curves for the whole TOSPG bridges in Korea are also developed using the total probability theorem. This study is expected to effectively contribute to the seismic risk assessment of railway lines, where a number of bridges are present.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2D
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• pp.243-248
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• 2008

Moisture damage of asphalt pavements can usually occur because of the loss of adhesion and cohesion between the asphalt binder and aggregate in the asphalt mixture due to presence of water. And this is one of the causes that is effect on the main distress of asphalt pavement. The objective of this study is to find out moisture damage characteristics of asphalt pavement. Effects of this study changes of the material properties and resistance characteristics of moisture damage on the asphalt mixtures under various temperatures and repeated immersion using indirect tensile test and modify Lottman test were evaluated during this study. The asphalt mixtures were produced using straight asphalt binder, SBS modified asphalt binder and aggregates. The material properties (resilient modulus, indirect tensile strength, failure energy and $DCSE_f$) of the asphalt mixtures were generally decreased with increasing to moisture damage caused by the number of repeated immersion. The decrease ratios of material properties by repeated immersion on SBS modified asphalt mixtures were lower than those of straight asphalt mixtures at all three test temperatures. As a conclusion, current criterion for evaluation moisture damage of asphalt mixtures is difficult for using distinction standard because of the limited evaluation criterion with one time immersion and single material property. Based on this research, to evaluate long term moisture damage on asphalt mixtures, material property tests of various kinds with repeated immersion test are considered.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.523-528
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• 2015

In this study, we evaluated the heating characteristics of single sonication and superposed two low-intensity ultrasonic sonication. Compare the results, the superposed sonication was showed a superior thermal effect than single sonication. And the maximum temperature was increased as 120-150%. The starting time of temperature rising has been shortened in superposed sonication. In addition, the time up to the maximum temperature has been shortened, too. In generally, as the ultrasonic intensity is higher, the more surface damage is occurred. However, in the case of superposed sonication, the same thermal effect had be confirmed without surface damage. Through the results of the study, we thought that the superposed sonication will be able to reduce the intensity of the ultrasonic treatment. And, by using the low-intensity, the more safe and more effect therapy will be possible in therapeutic ultrasound application.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.3
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• pp.269-273
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• 2015

The study investigated the effect of the distance between two collinear circumferential surface cracks on the primary stress corrosion crack (PWSCC) growth in alloy 600TT steam generator tubes using a finite element damage analysis based on the PWSCC initiation model and macroscopic phenomenological damage mechanics approach. The damage analysis method was verified by comparing the results to the previous study results. The verified method was applied to collinear circumferential surface PWSCCs. As a result, it was found that the collinear cracks showed earlier coalescence and penetration times than the a single crack, and the times increased with the distance. In addition, it is expected that penetration may occur before coalescence of two cracks if they are more than a specific distance apart.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.1
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• pp.75-82
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• 2015

Recently, many public auditing schemes have been proposed to support public auditability that enables a third party auditor to verify the integrity of data stored in the remote cloud server. To improve the performance of the auditor, several public auditing schemes support batch auditing which allows the auditor to handle simultaneously multiple auditing delegations from different users. However, when even one data is corrupted, the batch auditing will fail and individual and repeated auditing processes will be required. It is difficult to identify the corrupted data from the proof in which distinct data blocks and authenticators of distinct users are intricately aggregated. In this paper, we extend a public auditing scheme of Wang et al. to support batch auditing for multi-cloud and multi-user. We propose an identification scheme of the corrupted cloud when the data of a single cloud is corrupted in the batch auditing of multi-cloud and multi-user.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1D
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• pp.45-55
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• 2008

The objective of this research was to develop a VEPCD (ViscoElastoPlastic Continuum Damage) Model which is used to predict the behavior of asphalt concrete under various loading and temperature conditions. This paper presents the VEPCD model formulated in a tension mode and its validation using four hot mix asphalt (HMA) mixtures: dense-graded HMA, SBS, CR-TB, and Terpolymer. Modelling approaches consist of two components: the ViscoElastic Continuum Damage (VECD) mechanics and the ViscoPlastic (VP) theory. The VECD model was to describe the time-dependent behavior of HMA with growing damage. The irrecoverable (whether time-dependent or independent) strain has been described by the VP model. Based on the strain decomposition principle, these two models are integrated to form the VEPCD model. For validating the VEPCD model, two types of laboratory tests were performed: 1) a constant crosshead strain rate tension test, 2) a fatigue test with randomly selected load levels and frequencies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.112-118
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• 2013

The selection of appropriate ground motions and reasonable modification are becoming increasingly critical in reliable prediction on seismic performance of structures. A widely used amplitude scaling approach is not sufficient for robust structural evaluation considering a site specific seismic hazard because only one spectral value is matched to the design spectrum typically at the structural fundamental period. Hence alternative approaches for ground motion selection and modifications have been suggested. However, there is no means to evaluate such methodologies yet. In this study, it is focused to describe the main questions resided in the amplitude scaling approach and to propose a regression model for structural damage as point of comparison. Spectrum compatible approach whose resulting spectrum matches the design spectrum at the entire range of the structural period is considered as alternative to be compared to the amplitude scaling approach. The design spectrum is generated according to ASCE7-05.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.3
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• pp.328-337
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• 2010

The purpose of this study was to research the traumatized primary teeth and investigate following factors: sex, age, cause, place and time(of the year) of injury, elapsed time, area and type of injury, dental treatment and prognosis. The analysis includes total of 1533 traumatized primary teeth from 758 children aging from 6 months to 6 years(mean age: 2.8) from 2003 to 2007. The result follows : 1. The children of age between 1-2 and 2-3 were involved in the largest number of injuries in both sexes with boy/girl ratio of 1.77:1(p<0.001). 2. Fall and collision were the main causes of traumatic dental injury, especially in younger children(p<0.05). Places of injury occurrence varied: home, outdoors, and kindergarten. Warm climate accounts for frequent outdoor injuries in May, September and October(p<0.001). 3. Most of the children visited dental clinic within 24 hours of the injury(77.6%). From March to September, dental trauma occurrences were distributed evenly, except for Winter period(p<0.001). 4. Upper central incisors were the most commonly affected teeth, and the injuries usually involved 1 tooth or 2 teeth. 5. Periodontal tissue injuries dominated and subluxation was the most common type. Lateral luxation, enamel fracture, intrusion and root fracture followed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.148-156
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• 2022

Although most domestic concrete structures are simultaneously exposed to freeze-thaw and chloride environments, concrete durability in the field is evaluated by each single action, and the evaluation of chloride-caused damage of concrete requires additional indoor experimental analysis of chloride contents by coring samples from structures in the field. However, in Korea, policies to strengthen facility maintenance, such as 「Special Act on the Safety Control and Maintenance of Establishments」 and 「Framework Act on Sustainable Infrastructure Management」, have been established and implemented since 2018 and facilities subject to safety inspection management by the government and local governments increases, the effective simplification technology for the inspection and diagnosis of concrete structure is needed. Therefore, this study attempted to evaluate the possibility of determining the acceleration chloride penetration of freeze-thaw damaged concrete by using the surface rebound value. For this purpose, concrete specimens already having freeze-thaw damage by exposure to the freeze-thaw acceleration environment were immersed in chloride water. After that, the acceleration relationship of chloride penetration according to freeze-thaw damage was analyzed using the amount of chloride contents in concrete.

• Clinical and Experimental Pediatrics
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• v.48 no.5
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• pp.545-550
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• 2005

Purpose : Newborn brain tissue has to be dissociated into a single cell suspension for flow cytometric analysis of cell death during hypoxia-ischemia. Thus the development of a method to dissociate cells from the brain tissue with least damage and maintenance of membrane and antigen integrity remains the challenge for the in vivo application of this technique. We evaluated the efficacy of mechanical or enzymatic (collagenase or tryspin) methods of brain tissue disaggregation. Methods : The extent of the damage to the plasma membrane and loss of the characteristics of the membrane induced with each dissociation method was determined by comparing the flow cytometric results labeled with both fluorescent annexin V and propidium iodide of the newborn rat pup brain tissue in the control group (n=10) and in the 48-hour after hypoxia-ischemia group (n=10). Results : In the control group, the cell percentage of damaged, apoptotic and necrotic cells of both hemispheres with the mechanical dissociation method was significantly increased compared to the trypsin or collagenase method. In the 48-hour after hypoxia-ischemia group, the cell percentage of apoptotic and necrotic cells of the right hemisphere with the collagenase method significantly increased, and live cells significantly decreased compared to the left hemisphere, control group. Although the same trend was observed, the extent of alterations made with the trypsin method was significantly less compared to the collagenase method. Conclusion : The dissociation of neonatal brain tissue for flow cytometric analysis with collagenase was most efficacious with the least cell damage and preservation of the plasma membrane characteristics.