A review of recent results on transition metal doping of electronic oxides such as ZnO, TiO 2 , SnO 2 , BaTiO 3 , Cu 2 O, SrTiO 3 and KTaO 3 is presented. There is interest in achieving ferromagnetism with Curie temperatures above room temperature in such materials for applications in the field of spintronic devices, in which the spin of the carriers is exploited. The incorporation of several atomic per cent of the transition metals without creation of second phases appears possible under optimized synthesis conditions, leading to ferromagnetism. Pulsed laser deposition, reactive sputtering, molecular beam epitaxy and ion implantation have all been used to produce the oxide-based dilute magnetic materials. The mechanism is still under debate, with carrier-induced, double-exchange and bound magnetic polaron formation all potentially playing a role depending on the conductivity type and level in the material.

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This paper presents the natural frequency of a composite girder with corrugated steel web (CGCSW). A corrugated steel web has negligible in-plane axial stiffness, due to the unique characteristic of corrugated steel webs, which is called the accordion effect. Thus, the corrugated steel web only resists shear force. Further, the shear buckling resistance and out-of-plane stiffness of the web can be enhanced by using a corrugated steel web, since the inclined panels serve as transverse stiffeners. To take these advantages, the corrugated steel web has been used as an alternative to the conventional pre-stressed concrete girder. However, studies about the dynamic characteristics, such as the natural frequency of a CGCSW, have not been sufficiently reported, and it is expected that the natural frequency of a CGCSW is different from that of a composite girder with flat web due to the unique characteristic of the corrugated steel web. In this study, the natural frequency of a CGCSW was investigated through a series of experimental studies and finite element analysis. An experimental study was conducted to evaluate the natural frequency of CGCSW, and the results were compared with those from finite element analysis for verification purpose. A parametric study was then performed to investigate the effect of the geometric characteristics of the corrugated steel web on the natural frequency of the CGCSW. Finally, a simplified beam model to predict the natural frequency of a CGCSW was suggested.

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This paper presents a method for evaluating the reliability of an in-service highway bridge that considers the resistance capacity loss due to various corrosive environments. To demonstrate the application of the suggested method, a pre-stressed concrete-I (PSC-I) type girder was selected as a sample bridge. An analytical procedure was developed to quantitatively evaluate the performance degradation of a PSC-I girder bridge considering the traffic conditions, corrosive environment, and crack damage. The bridge performance was evaluated by considering traffic conditions, including the annual average daily traffic volume, heavy vehicle volume, and corrosive environment (mild, normal, and severe). To calculate the resistance capacity, all variables regarding the materials and sections were considered through probabilistic variances, Monte Carlo simulation, and the statistical characteristics of the resistance. The results showed that the performance degradation is sensitive to the important parameters of the traffic conditions and corrosive environment, which may decrease the structural reliability and lead to bridge failure. Cracks in a PSC-I girder may accelerate the performance degradation and affect the reliability level of the bridge. Therefore, a maintenance plan should be rationally considered depending on the site environment.

Abstract:The effects of traffic loads on existing bridges are quite different from those of design live loads because of the various traffic environments. However, the bridge maintenance and safety assessment of in-service bridges maintain the design load capacity without considering the current traffic environment. The real traffic conditions on existing bridges may require a load capacity that is considerably different from the design. Therefore, the required load capacity of an existing highway bridge should be determined according to the extreme load effects that the bridge will experience from the actual traffic environment during its remaining service life for more rational maintenance of the infrastructure. A simulation process was developed to determine evaluation vehicle loads for bridge safety assessment based on the extreme load effects that may occur during the remaining service life. Realistic probabilistic traffic models were used to reflect the actual traffic environment. The presented model was used to analyze the extreme load effect on pre-stressed concrete (PSC) and steel box girder bridges, which are typical bridge types. The traffic environmental conditions included the traffic volume (2000-40,000), the proportion of heavy vehicles (15-45%), and the consecutive vehicle traveling patterns. The spans of the sample bridges were 30 m (PSC bridge) and 45 or 60 m (steel box girder bridge). In the results, the extreme load effects tended to increase with either the traffic volume or proportion of heavy vehicles. The evaluation vehicle loads for bridge safety assessment may be adjusted with the traffic conditions, such as the traffic volume, the proportion of heavy vehicles, and the consecutive vehicle traveling patterns.

The Ministry of the Interior and Safety is a backbone of the disaster-management system in Korea and operates a prior consultation system for the management of the disaster and safety budget. This study analyzed problems and proposed improvement strategies for the pre-consultation system for the disaster and safety management budget, which has been implemented since 2015. The issues that were found in the budget plans for the fiscal years of 2016-2018 are that, first, the investment strategy of the disaster safety project is insufficient to reflect the characteristics of recent disaster safety accidents; second, the classification system of disaster and safety budget is indefinite; and third, investment priority criteria have redundancies. To firmly solidify the pre-consultation system, several possible solutions to these three main issues are suggested. First, disaster damages and losses should be compiled to find implications; second, the current classification system should be reviewed; and third, investment priority criteria in 2018 should be reviewed. Therefore, an improvement of the classification system and investment priority criteria is desired for more efficient management of the disaster and safety budget.

This paper proposes a gait phase classifier using a Recurrent Neural Network (RNN). Walking is a type of dynamic system, and as such it seems that the classifier made by using a general feed forward neural network structure is not appropriate. It is known that an RNN is suitable to model a dynamic system. Because the proposed RNN is simple, we use a back propagation algorithm to train the weights of the network. The input data of the RNN is the lower body's joint angles and angular velocities which are acquired by using the lower limb exoskeleton robot, ROBIN-H1. The classifier categorizes a gait cycle as two phases, swing and stance. In the experiment for performance verification, we compared the proposed method and general feed forward neural network based method and showed that the proposed method is superior.