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Improved criteria for the material properties and mix proportions of concrete slabs to enhance the performance of concrete pavements at Incheon international airport (IA) in the Republic of Korea are suggested. Gimpo IA and Gimhae IA were selected for comparison with Incheon IA based on their facility status and annual flight processing capability. After Incheon IA, Gimpo IA and Gimhae IA have the second and third largest annual numbers of flights per unit area of runway, respectively. Criteria for aggregate and mix proportions were chosen for improvement because of durability cracks (the major form of pavement distress at Incheon IA) due to the poor quality of aggregates used and repeated freeze–thaw cycles. Compared with the other airports, the mix specifications of the concrete slab at Incheon IA showed lower contents of cement and liquid admixture, a higher abrasion rate of coarse aggregate and a larger content of fines in the aggregate. Improved criteria were established based on a comparison of results. Concrete specimens were fabricated using the improved criteria and the performance of the concrete pavement was evaluated by testing the air content and freeze–thaw resistance of 12 mixes with different contents of cement, liquid admixture and fines in the aggregate.

The five cases of לֹא כִי in the Hebrew Bible (1Kgs 3:22–23 [3 times]; 2Kgs 20:10; Isa 30:16), which are contrasted with the more usual cases of לֹא כִּי, should not posit an additional meaning for כִי (i. e., »so« or »thus«) but be considered to have resulted from Mishnaic Hebrew interference to Biblical Hebrew. Two factors are discussed: that interference occurred between Biblical Hebrew and Mishnaic Hebrew and that לֹא כִי in Mishnaic Hebrew means »Not so«.

Objective: The objective of this study was to estimate standardized ileal digestibility (SID) of amino acids (AA) in growing pigs fed diets containing increasing levels of copra meal (CM) with β-mannanase supplementation.Methods: Twenty barrows (initial body weight: 34.43±0.11 kg) surgically fitted with T-cannulas at the distal ileum were individually housed in metabolism crates. Pigs were allotted to 5 dietary treatments in a completely randomized design with 4 replicates per treatment. The dietary treatments were: i) NC, negative control, corn-soybean meal (SBM) based diet, ii) PC, positive control, basal diet + 0.10% β-mannanase supplementation (800 IU/kg), iii) CM6, PC diet with 6% CM supplementation, iv) CM12, PC diet with 12% CM supplementation, and v) CM18, PC diet with 18% CM supplementation. A nitrogen-free diet was used to estimate basal endogenous losses of AA for SID calculation. All experimental diets contained 0.5% chromic oxide as an indigestible marker. Each period consisted of a 4-d diet adaptation period and a 3-d ileal digesta collection period.Results: There were no differences in apparent ileal digestibility (AID) and SID of all AA between the NC and PC treatments except that the PC treatment had lower AID and SID of glycine than the NC treatment (p

The pavement condition index (PCI) is a tool for evaluating pavement performance and is based on the type and severity of surface distress. It is used to determine maintenance times, methods and location priorities. Most previous PCI prediction models have considered only pavement age or traffic volume as a variable, without consideration of other factors that affect pavement distress. In this study, data from 12 airports were analysed using reports published from 1994 to 2013. The airport pavements were divided into homogeneous zones according to their function and structure. For improved management of concrete airport pavements, a non-linear PCI model was developed for the homogeneous zones and tornado diagrams were used to analyse the sensitivity of the PCI according to the independent variables of the model. The results showed that the developed model can predict the PCI of homogeneous zones of concrete airport pavements more reasonably by considering various factors that affect pavement distress.

When spalling occurs at a concrete pavement joint, partial depth repair (PDR) is implemented by removing the damaged part of a slab and filling the space with repair materials. However, re-repair is frequently also required because additional distress develops at the boundary of the repaired area due to improper PDR size in addition to poor quality of materials and construction methods. For the sustainability of pavement structures, it is necessary to study the PDR size based on the mechanical theory. Therefore, in this study, the PDR size for spalling was suggested based on the results of laboratory and field tests conducted using the impact echo (IE) method. The dynamic modulus estimated in the laboratory using the IE and forced resonance methods were compared for concrete specimens subjected to repetitive freeze–thaw cycles. In addition, the correlations of the dynamic modulus estimated by the methods with the compressive strength and absorption coefficient were analyzed. As a result, the IE method, for which vibration could be estimated on the same side of the specimen where impaction was applied, was selected for use on the pavement surface. Furthermore, the short-time Fourier transform technique was used instead of the fast Fourier transform, which has been commonly used for nondestructive methods, to minimize the noise in the field and, consequently, to estimate the dynamic modulus more accurately. The dynamic modulus was estimated according to the distance from the spalling end using the IE method at the Korea Expressway Corporation test road to identify the damaged range in the slab based on the severity of spalling. The dynamic modulus, compressive strength, and absorption coefficient tests were conducted in the laboratory for specimens cored from the concrete slab where the field test was performed. Finally, the PDR size was suggested according to the severity of spalling based on the damaged range in the slab, as determined by the field test and laboratory test results.

This study investigated the distress conditions of test sections of concrete pavement that have been used for more than the design life of 20 years. The study was performed using data from a highwa...

The repair method for pavements should be selected considering the structural capacity of sublayers, in addition to the conditions observed at the pavement surface, to reduce the recurrence of distress in the repaired area. However, it is practically impossible to include the structural capacity of sublayers in the database of the pavement management system (PMS) because this would require additional tests in all expressway sections. Therefore, an artificial neural network model for predicting the indirect tensile strength (ITS) of the intermediate layer of all asphalt pavement sections in an expressway was developed in this study, taking the international roughness index, rut depth, surface distress, and equivalent single axle load as independent variables. The ITS of specimens cored from target sections was measured in the laboratory, and the PMS data for the target sections were collected. The ITS was predicted by conducting a feedforward process prior to the training step. When the error between the predicted and measured ITSs exceeded the allowable error, the model was repetitively trained using the resilient backpropagation method until the error fell within the acceptable boundary. The model was validated by analyzing the correlations between the ITSs predicted from the data of the training and test sets. Finally, the model was complemented by the corresponding minimum and maximum values of the ITS measured at the target section.

Using reclaimed asphalt pavement (RAP) in road infrastructures is crucial for mitigating the environmental impact while controlling the construction costs. However, poorer low temperature performance may be experienced for mixtures containing RAP. In this paper, the effect of RAP on the material response at low temperature is investigated through mixture creep testing with the bending beam rheometer. Three different mathematical approaches are selected for further evaluation in combination with simple statistical analysis. Based on the experimental data, creep stiffness, m-value, relaxation modulus, thermal stress, and critical cracking temperature are computed and compared. As a result, no differences are found between the virgin mixture and that designed with 15% of RAP. Poorer performance is observed when more than 25% of RAP is incorporated; however, no significant variation was observed for a further increase up to 40% suggesting that higher amount RAP could be used depending on traffic level and climate.

In this study, strain gages were installed at the centre, edge, and corner of concrete pavement slabs of Incheon International Airport based on the slab depth, whereas thermometers were positioned ...

We propose an empirical method to analyze data from first-price procurements where bidders are asymmetric in their risk-aversion (CRRA) coefficients and distributions of private costs. Our Bayesian approach evaluates the likelihood by solving type-symmetric equilibria using the boundary-value method and integrates out unobserved heterogeneity through data augmentation. We study a new dataset from Russian government procurements focusing on the category of printing papers. We find that there is no unobserved heterogeneity (presumably because the job is routine), but bidders are highly asymmetric in their cost and risk-aversion. Our counterfactual study shows that choosing a type-specific cost-minimizing reserve price marginally reduces the procurement cost; however, inviting one more bidder substantially reduces the cost, by at least 5.5%. Furthermore, incorrectly imposing risk-neutrality would severely mislead inference and policy recommendations, but the bias from imposing homogeneity in risk-aversion is small.

Background Respiratory infection in children is a major disease that ranks high in outpatient and inpatient cases. In particular, the causes of community acquired pneumonia (CAP) vary depending on the individual susceptibility, epidemiological characteristics of the community, and season, and it is difficult to obtain samples for microbiological diagnosis. This study analysis that laboratory surveillance network of pathogen for pediatric CAP by linking the national community-based hospital and clinics and the Centers for Disease Control and Prevention (KCDC) to identify the distribution trend and prevalence of causative pathogens and to prevent antibiotic resistance of bacterial pathogens. Method The monitoring network was composed of the 28 secondary and tertiary medical institutions based on the national community, and the 24-month prospective study operated a community monitoring network for CAP in children. Results A total of 1023 cases were registered for nasopharyngeal aspirate or sputum in patients with CAP, and 711 cases (69.5%) were isolated by culture, S. aureus 131 cases (12.8%), S. pneumonia 92 cases (9%), H. influenzae 20 cases (2%). PCR of atypical pneumonia revealed 422 cases of M. pneumoniae (41.3%), 5 cases of C. pneumonia (0.5%), and 5 case (0.5%) of B. pertussis. Respiratory virus multiplex PCR test showed positive rates in 65.7%, human rhinovirus 312 (30.5%), RSV(A+B) 212 (20.7%), Adenovirus 123 (12%), Influenza (A+B) 53 (7.8%), CoV (OC43+NL63+229E) 69 (6.7%), HMPV 81 (7.9%), HBoV 51 (5%), PIV (1+2+3+4) 65 (6.4%) and HEV 30 (2.9%) Conclusion It will identify the pathogens that cause respiratory infections, and analyze the current status of antibiotic resistance to provide scientific evidence for management policies of domestic respiratory infection. Also, in preparation for the new epidemic, including COVID19, monitoring of respiratory infections in children and adolescents, especially community pneumonia, has become more important, and research should be continuously conducted in the future. The location and extent of involvement in the medulla were the most important factors associated with the severity of dysphagia after LMI.

The one-word negative response lō’ means “no” in Zech 4:5 and “yes” in Gen 18:15. This ambiguity is syntactic in nature and is handled and removed also by BH syntax.

In this study, a remodeling index (RMI) prediction model was developed to determine and prioritize target sections for large-scale repair works of deteriorated expressway concrete pavements in Korea. The unit sections that represent the distribution of the structural condition of entire analyzed sections were selected for jointed concrete pavement (JCP) and continuously reinforced concrete pavement (CRCP), and the RMI of the representative sections was rated by a panel of members. The model that predicts the RMI of aging JCP and CRCP after a few years hereafter was developed using the RMI obtained by the panel rating as a dependent variable, and the pavement conditions, pavement age, traffic volume, and weather conditions of the corresponding sections were considered as independent variables. The RMI sensitivity was analyzed according to each independent variable, and the appropriateness of the RMI prediction model was verified by comparing the RMIs in 2016 predicted in 2014 (future RMI in two years) with those in 2016 predicted in 2016 (present RMI). The entire aging expressway concrete-pavement sections were divided into homogeneous sections of suitable lengths for remodeling works by applying the RMI prediction model to each unit section. The priority for remodeling works was determined among the highly ranked homogeneous sections using the predicted RMI. The actual pavement conditions of a target section in which the remodeling priority had the highest rank were verified.

In this study, the surface segregation of Mg and Ca in Cu-Mg alloys containing a trace amount of Ca under an oxidative atmosphere and its effects on oxidation resistance were examined. The use of a Mg+Mg₂Ca master alloy as an alloying element for Mg rendered significant surface protection during melting and casting. During solid-state oxidation, the oxidation resistance was increased by the addition of Mg. Ca containing alloys with the same Mg exhibited a relatively higher oxidation resistance. From the phase diagram with the oxygen partial pressure as a function of the Mg content, the Ca containing alloy led to the formation of CaO as the primary oxide. The improved oxidation resistance of Ca containing alloys can be attributed to a mixed surface layer of CaO and MgO.

In this study, effect of Ca on phase stability and oxidation of Al₃Mg₂ at elevated temperature was investigated. From thermogravimetric analysis (TGA) at 420 °C, rapid weight gains in the initial stage and incubation were observed for Al₃Mg₂ and Ca-added Al₃Mg₂. After incubation for some time, Al₃Mg₂ sample exhibited the second weight growth, while Ca added sample exhibited continuous incubation during the testing time. The phase diagrams calculated by Factsage 7.1 revealed that Ca exists as Laves_C36 in Al₃Mg₂ and also forms Ca₃MgAl₄O10, following formation of MgO and MgAl₂O₄-spinel as primary and secondary oxides, respectively, on the surface during oxidation at 420 °C.

Dual-phase Al0.5CoCrFeMnNi high-entropy alloy consisted of face-centered cubic (FCC) and body-centered cubic (BCC) phases exhibited enhancement of both strength and strain hardening ability at 77 K. It resulted from back stress hardening in high work hardening due to large strength difference of two constituent phases with decreasing temperature.

In this study, a method to identify the representative section (RS) which can represent the pavement conditions of entire aged concrete expressway pavement (CEP) sections for the large-scale remodeling project, was developed based on pavement management system (PMS) data and an optimized approach. To fulfill this objective, various PMS data sets on the target section (TS) of concrete expressway pavement that exceeded 20 years of design life were collected with 100m intervals. Then, the first version of the optimized 100 RSs, which was a reasonable amount of data for analysis of aged CEP condition, was selected based on the different severity levels of surface damage and international roughness index (IRI) data. Secondly, another crucial PMS factor: the alkali-silica reaction (ASR) severity level, was considered and substituted partially in the previously selected 100 RSs to provide additional and reasonable representative characteristics. Finally, the characteristics of the RS were evaluated and verified by considering whether the various distress size rankings of the RS were uniformly distributed within the entire distress size ranking of the total jointed concrete pavement (JCP) and continuously reinforced concrete pavement (CRCP) TS. It was found that the RS selection approach and corresponding criteria proposed in this study, based on the optimization approach, could be successfully used to determine the future large-scale remodeling priority of the old concrete expressway pavements.

For the sustainable management of pavements, predicting the condition of the pavement structure using a consistent and accurate method is necessary. The intermediate layer situated immediately below the surface layer has the greatest effect on the condition of the pavement structure. As a result, to accurately predict the condition of a pavement structure, the mechanistic properties of the intermediate layer are very important. Fracture toughness (FT)—a mechanistic property of the intermediate layer—is an important factor in predicting the distress that develops on the pavement surface. However, measuring FT consistently is practically impossible by coring asphalt pavement over the entire pavement section. Therefore, an artificial neural network (ANN) model—developed by using pavement surface conditions and traffic volume—can predict the FT of the intermediate layer of expressway asphalt pavements. Several ANN models have been developed by applying various optimizers, ANN structures, and preprocessing methods. The optimal model was selected by analyzing the predictive performance, error stability, and distribution of the developed models. The final selected model showed small stable errors, and the distributions of the predicted and measured FTs were similar. Furthermore, FT limits were set with outliers. Future asphalt pavement conditions can be predicted throughout the expressway network by using the proposed model without coring samples.