• Smart Structures and Systems
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• v.17 no.6
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• pp.1087-1105
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• 2016

Traffic load and volume is one of the most important physical quantities for bridge safety evaluation and maintenance strategies formulation. This paper aims to conduct the statistical analysis of traffic volume information and the multimodal modeling of gross vehicle weight (GVW) based on the monitoring data obtained from the weigh-in-motion (WIM) system instrumented on the arch Jiubao Bridge located in Hangzhou, China. A genetic algorithm (GA)-based mixture parameter estimation approach is developed for derivation of the unknown mixture parameters in mixed distribution models. The statistical analysis of one-year WIM data is firstly performed according to the vehicle type, single axle weight, and GVW. The probability density function (PDF) and cumulative distribution function (CDF) of the GVW data of selected vehicle types are then formulated by use of three kinds of finite mixed distributions (normal, lognormal and Weibull). The mixture parameters are determined by use of the proposed GA-based method. The results indicate that the stochastic properties of the GVW data acquired from the field-instrumented WIM sensors are effectively characterized by the method of finite mixture distributions in conjunction with the proposed GA-based mixture parameter identification algorithm. Moreover, it is revealed that the Weibull mixture distribution is relatively superior in modeling of the WIM data on the basis of the calculated Akaike's information criterion (AIC) values.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.10
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• pp.1248-1253
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• 2019

Using current evacuation methods, a crew describes the physical location of an accident and guides evacuation using alarms and emergency guide lights. However, in case of an accident on a large and complex building, an intelligent and effective emergency evacuation system is required to ensure the safety of evacuees. Therefore, several studies have been performed on intelligent path finding and emergency evacuation algorithms which are centralized guidance methods using gathered data from distributed sensor nodes. However, another important aspect is effective rescue guidance in an emergency situation. So far, there has been no consideration on the efficient rescue guidance scheme. Therefore, this paper proposes the genetic algorithm based emergency rescue guidance method using distributed wireless sensor networks. Performance evaluation using a computer simulation shows that the proposed scheme guarantees efficient path finding. The fitness converges to the minimum value in reasonable time. The density of each exit node is remarkably decreased as well.

• Smart Structures and Systems
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• v.30 no.4
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• pp.339-351
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• 2022

Evaluating the current condition of existing structures is of primary importance for economic and safety reasons. This can be addressed by Structural System Identification (SSI). A reliable static SSI depends on well-designed sensor configuration and loading cases, as well as efficient parameter estimation algorithms. Static SSI by the Measurement Error-Minimizing Observability Method (MEMOM) is a model-based deterministic static SSI method that could estimate structural parameters from static responses. In the current state of the art, this method is only applicable when structures are subjected to one loading case. This might lead to lack of information in some local regions of the structure (such as the null curvatures zones). To address this issue, the SSI by MEMOM using multiple loading cases is proposed in this work. Observability equations obtained from different loading cases are concatenated simultaneously and an optimization procedure is introduced to obtain the estimations by minimizing the discrepancy between the predicted response and the measured one. In addition, a Genetic-Algorithm (GA)-based Optimal Sensor Placement (OSP) method is proposed to tackle the OSP problem under multiple static loading cases for the very first time. In this approach, the Fisher Information Matrix (FIM)'s determinant is used as the metric of the goodness of sensor configurations. The numerical examples of a 3-span continuous bridge and a 13-story frame, are analyzed to validate the applicability of the extended SSI by MEMOM and the GA-based OSP method.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.968-980
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• 2023

The dynamic structural responses are sensitive to the time-frequency content of seismic waves, and seismic input motions in time-history analysis are usually required to be compatible with design response spectra according to nuclear codes. In order to generate spectra-compatible input motions while maintaining the intrinsic non-stationarity of seismic waves, an improved time-domain approach is proposed in this paper. To maintain the nonstationary characteristics of the given seismic waves, a new time-frequency envelope function is constructed using the Hilbert amplitude spectrum. Based on the intrinsic mode functions (IMFs) obtained from given seismic waves through variational mode decomposition, a new corrective time history is constructed to locally modify the given seismic waves. The proposed corrective time history and time-frequency envelope function are unique for each earthquake records as they are extracted from the given seismic waves. In addition, a dimension reduction iterative technique is presented herein to simultaneously superimpose corrective time histories of all the damping ratios at a specific frequency in the time domain according to optimal weights, which are found by the genetic algorithm (GA). Examples are presented to show the capability of the proposed approach in generating spectra-compatible time histories, especially in maintaining the nonstationary characteristics of seismic records. And numerical results reveal that the modified time histories generated by the proposed method can obtain similar dynamic behaviors of AP1000 nuclear power plant with the natural seismic records. Thus, the proposed method can be efficiently used in the design practices.

• Toxicological Research
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• v.29 no.4
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• pp.263-278
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• 2013

The silkworm extract powder contain 1-deoxynojirimycin (DNJ), a potent ${\alpha}$-glycosidase inhibitor, has therapeutic potency against diabetes mellitus. Therefore, natural products containing DNJ from mulberry leaves and silkworm are consumed as health functional food. The present study was performed to evaluate the safety of the silkworm extract powder, a health food which containing the DNJ. The repeated toxicity studies and gentic toxicity studies of the silkworm extract powder were performed to obtain the data for new functional food approval in MFDS. The safety was evaluated by a single-dose oral toxicity study and a 90 day repeated-dose oral toxicity study in Sprague-Dawley rats. The silkworm extract powder was also evaluated for its mutagenic potential in a battery of genetic toxicity test: in vitro bacterial reverse mutation assay, in vitro chromosomal aberration test, and in vivo mouse bone marrow micronucleus assay. The results of the genetic toxicology assays were negative in all of the assays. The approximate lethal dose in single oral dose toxicity study was considered to be higher than 5000 mg/kg in rats. In the 90 day study, the dose levels were wet at 0, 500, 1000, 2000 mg/kg/day, and 10 animals/sex/dose were treated with oral gavage. The parameters that were monitored were clinical signs, body weights, food and water consumptions, ophthalmic examination, urinalysis, hematology, serum biochemistry, necropsy findings, organ weights, and histopathological examination. No adverse effects were observed after the 90 day administration of the silkworm extract powder. The No-Observed-Adverse-Effect-Level (NOAEL) of silkworm extract powder in the 90 day study was 2000 mg/kg/day in both sexes, and no target organ was identified.

• The Korean Society of Law and Medicine
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• v.23 no.1
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• pp.121-148
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• 2022

CRISPR-Cas9 is one of the gene-editing technologies that infinite potential. It may provide human beings with many benefits or cause unanticipated challenges. The governance as standards setting or regulation of gene-editing technologies can contribute to keeping a balance between scientific value and ethical commitments. Guaranteeing public participation provides an additional opportunity to think about ethical and moral considerations: For whose benefit the internationally discussed governance of gene-editing technologies is directed at? There is a doubt regarding whether the governance justifies scientific researchers' gene-editing research. Suppose that governance promotes the advancement of CRISPR-Cas9, it should also encourage greater research responsibility. If not, there may be tragedies brought about by the misconduct of researchers. Thus, the essential matter on the governance for the research of CRISPR-Cas9 is the researchers' responsibility.

• Journal of Food Hygiene and Safety
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• v.38 no.4
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• pp.246-254
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• 2023

V. parahaemolyticus causes waterborne and foodborne disease such as acute diarrhea. In this study, V. parahaemolyticus isolates from seawater, fish tanks, and distributed fishery products in Jeju were investigated for potential toxin or species-specific genes (tdh, trh, tlh, and toxR) using RT-PCR and their genetic characteristics were analyzed using Pulsed-field gel electrophoresis (PFGE). Overall, V. parahaemolyticus of 90 strains (36.7%), including 33 strains from seawater, 8 strains from fish tanks, and 50 strains from fishery products, were isolated from 245 samples. All V. parahaemolyticus strains did not detect the tdh gene, whereas all strains detected tlh or toxR genes. In addition, trh genes were detected in 3 strains from seawater and 1 strain from fishery products. Monthly quantitative testing of seawater revealed that V. parahaemolyticus was positively correlated with water temperature. The 90 strains of V. parahemolyticus obtained in this study showed by gene homology between types, ranging from 64.0-97.3%. Among these, thirteen types showed 100% homology between genes. These results indicate that continuous monitoring is needed to facilitate food poisoning epidemiological investigations because some isolated V. parahaemolyticus strains harbored toxin genes and V. parahaemolyticus strains isolated from seawater, fish tanks, and distributed fishery products showed genetic similarity.

• Journal of Food Hygiene and Safety
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• v.39 no.3
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• pp.181-190
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• 2024

Bovine mastitis-associated Escherichia coli (BMEC) is considered the main causative agent of significant financial losses in the dairy industry worldwide, as it alters both the quantity and quality of milk produced and increases the rate of culling. This creates a variety of challenges for researchers, veterinarians, and farmers in understanding and determining the most effective therapies and diagnostic techniques. Subclinical mastitis is particularly concerning, as infected bovines exhibit no obvious symptoms and continue to secrete apparently normal milk over an extended period, allowing the causative pathogen, E. coli, to spread within the herd. For effective prevention, understanding the pathogenesis of mastitis through three stages invasion, infection, and inflammation is essential. To date, no clear correlation has been found between virulence factors and pathogenicity contributing to the clinical severity of BMEC. Multidrug-resistant E. coli and the evolution of novel resistance mechanisms have become concerns owing to the extensive use of antibiotics to treat mastitis. Therefore, it is vital to explore alternative controls to enhance the efficacy of BMEC treatment. Over the past 30 years, various genetic typing techniques have been used to examine the subspecies-level epidemiology of bovine mastitis. These studies have advanced our understanding of the origin, transmission pathway, population structure, and evolutionary relatedness of BMEC strains. In this review we provide an overview of BMEC, including insights into its etiology, genetic relationship, pathogenesis, and management of the disease, as well as new therapy options.

• Journal of Veterinary Science
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• v.22 no.5
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• pp.68.1-68.15
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• 2021

Background: Colistin and carbapenem-resistant bacteria have emerged and become a serious public health concern, but their epidemiological data is still limited. Objectives: This study examined colistin and carbapenem resistance in Escherichia coli and Salmonella from pigs, pig carcasses, and pork in Thailand, Lao PDR, and Cambodia border provinces. Methods: The phenotypic and genotypic resistance to colistin and meropenem was determined in E. coli and Salmonella obtained from pigs, pig carcasses, and pork (n = 1,619). A conjugative experiment was performed in all isolates carrying the mcr gene (s) (n = 68). The plasmid replicon type was determined in the isolates carrying a conjugative plasmid with mcr by PCR-based replicon typing (n = 7). The genetic relatedness of mcr-positive Salmonella (n = 11) was investigated by multi-locus sequence typing. Results: Colistin resistance was more common in E. coli (8%) than Salmonella (1%). The highest resistance rate was found in E. coli (17.8%) and Salmonella (1.7%) from Cambodia. Colistin-resistance genes, mcr-1, mcr-3, and mcr-5, were identified, of which mcr-1 and mcr-3 were predominant in E. coli (5.8%) and Salmonella (1.7%), respectively. The mcr-5 gene was observed in E. coli from pork in Cambodia. Two colistin-susceptible pig isolates from Thailand carried both mcr-1 and mcr-3. Seven E. coli and Salmonella isolates contained mcr-1 or mcr-3 associated with the IncF and IncI plasmids. The mcr-positive Salmonella from Thailand and Cambodia were categorized into two clusters with 94%-97% similarity. None of these clusters was meropenem resistant. Conclusions: Colistin-resistant E. coli and Salmonella were distributed in pigs, pig carcasses, and pork in the border areas. Undivided-One Health collaboration is needed to address the issue.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.415-422
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• 2021

Cotton is an important fiber crop, and its seeds are used as feed for dairy cattle. Crop biotechnology has been used to improve agronomic traits and quality in the agricultural industry. The frequent unintentional release of LM cotton into the environment in South Korea is attributed to the increased application of living modified (LM) cotton in food, feed, and processing industries. To identify and monitor the LM cotton, a method for detecting the approved LM cotton in South Korea is required. In this study, we developed a method for the simultaneous detection of four LM cotton varieties, MON757, MON88702, COT67B, and GHB811. The genetic information of each LM event was obtained from the European Commission-Joint Research Centre and Animal and Plant Quarantine Agency. We designed event-specific primers to develop a multiplex PCR method for LM cotton and confirmed the specific amplification. Using specificity assay, random reference material(RM) mixture analysis and limit of detection(LOD), we verified the accuracy and specificity of the multiplex PCR method. Our results demonstrate that the method enabled the detection of each event and validation of the specificity using other LM RMs. The efficiency of multiplex PCR was further verified using a random RM mixture. Based on the LOD, the method identified 25 ng of template DNA in a single reaction. In summary, we developed a multiplex PCR method for simultaneous detection of four LM cotton varieties, for possible application in LM volunteer analysis.