• Journal of the Korea Safety Management & Science
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• v.16 no.1
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• pp.79-88
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• 2014

The rapid growth of complexity and scale can be witnessed in the design and development of modern systems. As such, the severity of damages in the occasional accidents has attracted great deal of attention lately. Although a variety of methods have so far been studied to overcome or reduce the disastrous results of hazards, the issues seem still persistent and even complicated due to the situation mentioned above. The concept of functional safety has been regarded as one approach to handling the matters by shifting up to the functions level from the consideration of each physical component itself. The outcomes of those efforts would be the international standards on functional safety such as IEC 61508 and its relatives including IEC 62278, EN 50128, ISO26262, and so on. In this paper, a method of how hazards can be analyzed to be coped with those standards has been studied. In the method proposed, the systems modeling language (SysML) is playing a key role to model and analyze the hazards from the viewpoint of functional safety. The approach taken has been applied in the analysis of the hazards in railroad systems. In spite of focusing on the individual components hazards, the method based on functional safety has analyzed them collectively with the added effect of identifying the cause originated from the interface between the functions.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.6
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• pp.7-15
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• 2002

In this paper, the nonlinear parameter estimation method using the estimated hysteresis of each structural members was studied for the purpose of efficient seismic damage prediction and estimation of MDOF nonlinear structural model in the shaking table test. The hysteresis of each structural members can be obtained by the conversion of measured response histories into relative motions of each structural members and member forces. These hysteresis can be used to evaluate various kinds of damage indices of each structural members. The MDOF nonlinear structural model for further analysis(re-analysis) can be easily reconstructed using estimated nonlinear structural parameters of each structural members. To demonstrate the proposed techniques, several numerical and experimental example analyses are carried out. The results indicate that the proposed method can be very useful to assess local seismic damages of structures.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.638-645
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• 2007

Computers are increasingly being introduced into safety and reliability critical systems. The safe and reliable operation of these systems cannot be taken for granted. Malfunctions of these systems can have potentially catastrophic consequences and they have already been involved in serious accidents. Software fault prevention, fault tolerance, fault removal and fault forecasting are the techniques to be used, implemented and verified for embedded software in critical systems as the contributors to safety and reliability of the software. To use them when developing a software product, a relationship must be established between them and the development processes, the methods and techniques to be used to develop software, as well as with the different product architectures. Railroad signaling system software is a safety-critical embedded software with realtime and high reliability requirements. The primary purpose of the safety management is to prevent the loss of lives or physical damages arising from potential hazards in the railroad signaling system. This study provides a systematic approach to analysis of potential hazards for their management during the system life cycle to assure the identification and definition of the most appropriate hazards.

• Journal of the Society of Disaster Information
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• v.10 no.1
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• pp.98-104
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• 2014

A new prototype software package has been developed by integrating two existing programs designed to predict and maneuver chemical and nuclear disasters in order to set up a response system for dealing with the combined two disasters. The protype is designed to be mainly used by civil defence officers, together with an identification of 625 scenarios of chemical and nuclear disasters. The package is expected to contribute to upgrade a more systematic regional public protection plan for chemical and nuclear disasters. In addition, it enables all relevant local divisions to share disaster information in real time, resulting in a minimization of possible fatal damages.

• Journal of the Korea Safety Management & Science
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• v.11 no.1
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• pp.1-6
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• 2009

The specific feature of trains as a means of transportation is that, on one side, at once they can carry big loads but, at the same time, if an accident occurs, it potentially leads to many human casualties or big material losses. Especially, train accidents caused by bad weather conditions result in many fatal losses of human lives and property. In Korea many railways run either in mountainous areas or along rivers thus making them especially susceptible to natural hazards. The types of damages inflicted by heavy rains resulting from rapidly changing meteorological conditions are diverse; and not only their scope is big but also they repeat regularly. Consequently, this study analyses the reasons why such effects of heavy rains on the railway conditions, damage to the railways caused by heavy rains or cases of stone fall as well as other types of accidents are not avoided. Study also, on the basis of laws related to movement in poor weather conditions and specifics of train braking, identifies systematic and technical problems and suggests and emphasizes new complex measures on their prevention.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.38-38
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• 2018

The genus Carduus (Asteraceae), containing ca. 90 species, is mainly distributed in Eurasia and Africa. Carduus species are one of the most hazardous invasive species, which causes serious environmental threats and biodiversity damages in North America. Thus, the member of Carduus are targeted for classical biological control in this region. Here, we provide the complete cp genome of Carduus crispus using next-generation sequencing technology. The size of cp genomes of C. crispus is 152,342 bp. It shows a typical quadripartite structure, consisting of the large single copy (LSC; 83,254 bp), small single copy (SSC; 18,706 bp), separated by a pair of inverted repeats (IRs; 25,191 bp). It contains 115 unique genes of which 21 genes duplicated in the IR regions. The cpSSR regions of Carduus species were searched through the complete chloroplast genome sequence using a tandem repeat search tool in Geneious with the parameters set to ${\geq}7$ mononucleotide repeats, ${\geq}4$ di- and trinucleotide repeats, and ${\geq}3$ tetra-, penta-, and hexanucleotide repeats. A total of 22 repeat motifs were identified, which may be useful for molecular identification of Korean Carduus species (C. cripus), and providing a guideline for its conservation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.103-114
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• 2003

This paper aims to propose a method that helps maintenance engineers to evaluate the damage states of bridge structure systems by using a Fuzzy Fault Tree Analysis. It may be stated that Fuzzy Fault Tree Analysis may be very useful for the systematic and rational fuzzy reliability assessment for real bridge structure systems problems because the approach is able to effectively deal with all the related bridge structural element damages in terms of the linguistic variables that incorporate systematically experts experiences and subjective judgement. This paper considers these uncertainties by providing a fuzzy reliability-based framework and shows that the identification of the optimum maintenance scenario is a straightforward process. This is achieved by using a computer program for LIFETIME. This program can consider the effects of various types of actions on the fuzzy reliability index profile of a deteriorating structures. Only the effect of maintenance interventions is considered in this study. However. any environmental or mechanical action affecting the fuzzy reliability index profile can be considered in LIFETIME. Numerical examples of deteriorating bridges are presented to illustrate the capability of the proposed approach. Further development and implementation of this approach are recommended for future research.

• Structural Engineering and Mechanics
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• v.56 no.5
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• pp.871-897
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• 2015

This paper presents a novel method based on sensitivity of structural response for identifying both the system parameters and input excitation force of a bridge. This method, referred to as "Adjoint Variable Method", is a sensitivity-based finite element model updating method. The computational cost of sensitivity analyses is the main concern associated with damage detection by these methods. The main advantage of proposed method is inclusion of an analytical method to augment the accuracy and speed of the solution. The reliable performance of the method to precisely indentify the location and intensity of all types of predetermined single, multiple and random damages over the whole domain of moving vehicle speed is shown. A comparison study is also carried out to demonstrate the relative effectiveness and upgraded performance of the proposed method in comparison to the similar ordinary sensitivity analysis methods. Moreover, various sources of error including the effects of noise and primary errors on the numerical stability of the proposed method are discussed.

• Smart Structures and Systems
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• v.25 no.6
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• pp.733-749
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• 2020

This study presents a computer vision-based approach for representing time evolution of structural damages leveraging a database of inspection images. Spatially incoherent but temporally sorted archival images captured by robotic cameras are exploited to represent the damage evolution over a long period of time. An access to a sequence of time-stamped inspection data recording the damage growth dynamics is premised to this end. Identification of a structural defect in the most recent inspection data set triggers an exhaustive search into the images collected during the previous inspections looking for correspondences based on spatial proximity. This is followed by a view synthesis from multiple candidate images resulting in a single reconstruction for each inspection round. Cracks on concrete surface are used as a case study to demonstrate the feasibility of this approach. Once the chronology is established, the damage severity is quantified at various levels of time scale documenting its progression through time. The proposed scheme enables the prediction of damage severity at a future point in time providing a scope for preemptive measures against imminent structural failure. On the whole, it is believed that the present study will immensely benefit the structural inspectors by introducing the time dimension into the autonomous condition assessment pipeline.

• Computers and Concrete
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• v.13 no.2
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• pp.209-220
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• 2014

Vibration based damage detection is very popular in the civil engineering area. Especially, special structures like dams, long-span bridges and high-rise buildings, need continues monitoring in terms of mechanical properties of material, static and dynamic behavior. It has been stated in the International Commission on Large Dams that more than half of the large concrete dams were constructed more than 50 years ago and the old dams have subjected to repeating loads such as earthquake, overflow, blast, etc.,. So, some unexpected failures may occur and catastrophic damages may be taken place because of theloss of strength, stiffness and other physical properties of concrete. Therefore, these dams need repairs provided with global damage evaluation in order to preserve structural integrity. The paper aims to show the effectiveness of the model updating method for global damage detection on a laboratory arch dam model. Ambient vibration test is used in order to determine the experimental dynamic characteristics. The initial finite element model is updated according to the experimentally determined natural frequencies and mode shapes. The web thickness is selected as updating parameter in the damage evaluation. It is observed from the study that the damage case is revealed with high accuracy and a good match is attained between the estimated and the real damage cases by model updating method.