• Structural Engineering and Mechanics
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• v.55 no.6
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• pp.1139-1155
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• 2015

In this study, a new retrofitting method for improving the seismic performance of reinforced concrete column was presented, in which prestressed steel strips were utilized as retrofitting stuff to confine the reinforced concrete column transversely. In order to figure out the seismic performance of concrete column specimen retrofitted by such prestressed steel strips methods, a series of quasi-static tests of five retrofitted specimens and two unconfined column specimen which acted as control specimens were conducted. Based on the test results, the seismic performance including the failure modes, hysteresis performance, ductility performance, energy dissipation and stiffness degradation of all these specimens were fully investigated and analyzed. And furthermore the influences of some key parameters such as the axial force ratios, shear span ratios and steel strips spacing on seismic performance of those retrofitted reinforced concrete column specimens were also studied. It was shown that the prestressed steel strips provided large transverse confining effect on reinforced concrete column specimens, which resulted in improving the shearing bearing capacity, ductility performance, deformation capacity and energy dissipation performance of retrofitted specimens effectively. In comparison to the specimen which was retrofitted by the carbon fiber reinforced plastics (CFRP) strips method, the seismic performance of the specimens retrofitted by the prestressed steel strips was a bit better, and with much less cost both in material and labor. From this research results, it can be concluded that this new retrofitting method is really useful and has significant advantages both in saving money and time over some other retrofitting methods.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.4
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• pp.247-254
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• 2015

Ride comfort is one of the major factors in evaluating the performance of the vehicle. Tire is closely related to the ride comfort of the vehicle as the only parts in contact with the road surface directly. Vertical stiffness which is one of the parameters to evaluate the tire performance is great influence on the ride comfort. In general, the lower the vertical stiffness, the ride comfort is improved. Research for improving the ride comfort has been mainly carried out by optimizing the shape of the pneumatic tire. However, demand for safety of the vehicle has been increased recently such as a run-flat tire which is effective in safety improvement. But a run-flat tire have trouble in practical use because of poor ride comfort than general tire. Therefore, In this paper, the research was carried out for improving the ride comfort through the optimization of the SIR shape inside a run-flat tire. Meta-model was generated by using the design of experiment and it was able to reduce the time for the finite element analysis of optimization. In addition, Shape optimization for improving the ride comfort was performed by using the genetic algorithm which is one of the global optimization techniques.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1116-1124
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• 2004

In these days, a vehicle simulator has been developed with a VR(Virtual Reality) system. A VR system must provide a vehicle simulator with natural interaction, sufficient immersion and realistic images. In addition, a VR system must present a driver with the realistic driving situation. To achieve these, it is important to obtain a fast and uniform rendering performance regardless of the complexity of virtual worlds. In this paper, the factors to improve the reality for the VR based vehicle simulator have been investigated. For the purpose, the modeling and the rendering methods which offer an improved performance for complex VR applications as the 3D road model have been implemented and verified. Then, we experiment on the influence of graphic and sound factors to the driver, and analyze each result for improving the reality such as the driver's viewport, the form of texture, the lateral distance of the side object, and the sound effect. These factors are evaluated on the driving system which is constructed for qualitative analysis. The research results could be used for improving the reality of the VR based vehicle simulator.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.4
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• pp.145-154
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• 1994

This paper proposes an efficient method for improving the training performance of the neural network by using a hybrid of a stochastic approximation and a backpropagation algorithm. The proposed method improves the performance of the training by appliying a global optimization method which is a hybrid of a stochastic approximation and a backpropagation algorithm. The approximate initial point for a stochastic approximation and a backpropagation algorihtm. The approximate initial point for fast global optimization is estimated first by applying the stochastic approximation, and then the backpropagation algorithm, which is the fast gradient descent method, is applied for a high speed global optimization. And further speed-up of training is made possible by adjusting the training parameters of each of the output and the hidden layer adaptively to the standard deviation of the neuron output of each layer. The proposed method has been applied to the parity checking and the pattern classification, and the simulation results show that the performance of the proposed method is superior to that of the backpropagation, the Baba's MROM, and the Sun's method with randomized initial point settings. The results of adaptive adjusting of the training parameters show that the proposed method further improves the convergence speed about 20% in training.

• Structural Engineering and Mechanics
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• v.74 no.4
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• pp.481-494
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• 2020

In this paper, a probability-based procedure to evaluate the performance of existing RC structures exposed to seismic and fire actions is presented. The procedure is demonstrated with reference to an existing old school building, located in Italy. The vulnerability assessment of the building highlights deficiencies under both static and seismic loads. Retrofit operations are designed to achieve the seismic safety. The idea of the work consists in assessing the performance of the existing and retrofitted building in terms of both the seismic and fire resistance. The seismic retrofit and fire resistance upgrading follow different paths, depending on the specific configuration of the building. A good seismic retrofit does not entail an improving of the fire resistance and vice versa. The goal of the current work is to study the variation of response due to the uncertainties considered in records/fire curves selection and to carry out the assessment of the studied RC structure by obtaining fragility curves under the effect of different records/temperature. The results show the fragility curves before and after retrofit operations and both in terms of seismic performance and fire resistance performance, measuring the percent improving for the different limit states.

• Journal of Construction Engineering and Project Management
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• v.10 no.1
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• pp.1-15
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• 2020

With the increased dependence on subcontracting in the construction industry, the operational relationship between main contractors and subcontractor plays an imperative role in successful project delivery. Consequently, improving this relationship increases the probability of project success and enhancing project performance. A wide range of research has confirmed that partnering improves the main contractor-subcontractor relationship. Though the positive impact of partnering on project performance is supported by a plethora of evidence, the guiding theory on practical partnering process steps is limited. The study aimed at improving subcontracting in the construction industry through a partnering process relevant to Zambia guided by factors obtained from industry expects. Questionnaire surveys and Semi-structured interview were adopted to investigate the perception of construction industry professionals and academics towards the main contractor-subcontractor relationship along with improvement factors. The findings showed that the relationship between main contractors and subcontractors on most projects in Zambia is unsatisfactory therefore justifying attention. Top factors that can enhance the main contractor-subcontractor relationship were identified. From the factors deduced and guidelines on partnering best practices, a project partnering model was developed.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.1167-1174
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• 2020

This study aims to evaluate the effect of computerized tax services in improving tax performance by moderating governance principles in Jordanian tax income departments. The study is based on a questionnaire distributed to income tax auditors, who were chosen by the simple random sampling method, so that 170 questionnaires were subjected to statistical analysis. The study models were formulated in the form of simple and multiple regression equations to test the hypotheses of the study, in addition to relying on One Sample T-test to calculate the mean of questionnaire answers. The most prominent research results is that the application of tax governance principles through the provision of computerized tax services is reflected in the increase in confidence between taxpayers and income tax departments, the efficiency of tax performance, and tax proceeds. Also, the study pointed out the importance of the income tax departments to prepare strategic plans regarding the development and the follow-up of modern technologies related to computerized tax services. It especially regards linking and collecting tax from taxpayers such as via electronic tax payment and collection system, in order to ensure the speed of completion, accuracy of calculation, and raising the efficiency of tax performance.

• Journal of Internet Computing and Services
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• v.22 no.6
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• pp.1-8
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• 2021

With the rapid growth of intelligent devices and communication technologies, 5G network environment has become more heterogeneous and complex in terms of service management and orchestration. 5G architecture requires supportive technologies to handle the existing challenges for improving the Quality of Service (QoS) and the Quality of Experience (QoE) performances. Among many challenges, traffic steering is one of the key elements which requires critically developing an optimal solution for smart guidance, control, and reliable system. Mobile edge computing (MEC), software-defined networking (SDN), network functions virtualization (NFV), and deep learning (DL) play essential roles to complementary develop a flexible computation and extensible flow rules management in this potential aspect. In this proposed system, an accurate flow recommendation, a centralized control, and a reliable distributed connectivity based on the inspection of packet condition are provided. With the system deployment, the packet is classified separately and recommended to request from the optimal destination with matched preferences and conditions. To evaluate the proposed scheme outperformance, a network simulator software was used to conduct and capture the end-to-end QoS performance metrics. SDN flow rules installation was experimented to illustrate the post control function corresponding to DL-based output. The intelligent steering for network communication traffic is cooperatively configured in SDN controller and NFV-orchestrator to lead a variety of beneficial factors for improving massive real-time Internet of Things (IoT) performance.

• Industrial Engineering and Management Systems
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• v.3 no.1
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• pp.52-58
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• 2004

This report examines the issue of designing an efficient production system by increasing several types of flexibility. Increasing manufacturing flexibility is a key strategy for efficiently improving market responsiveness in the face of uncertain market demand for final products. The manufacturing system comprises multiple plants, of which individual plants have multiple manufacturing lines that are designed to produce limited types of products in accordance with their size and materials. Imbalance in the workload occurs among plants as well as among manufacturing lines because of fluctuations in market demand for final products. Thereby, idleness of some manufacturing lines and longer lead times in some manufacturing lines occur as a result of the high workload. We clarify how these types of flexibility affect manufacturing performance by improving only one type of flexibility or by improving multiple types of flexibility simultaneously. The average lead time and the imbalance in workload are adopted as measures of manufacturing performance. Three types of manufacturing flexibility are interrelated: machine flexibility, routing flexibility, and process flexibility. Machine flexibility refers to the various types of operations that a machine can perform without requiring the prohibitive effort of switching from one order to another. Routing flexibility is the capability of processing a given set of part types using more than one line (alternative line) in the plant. Process flexibility results from being able to build different types of final products at the same plant.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.799-806
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• 2004

This paper presents a scheme for finding an optimal combination of design parameters affecting on the handling performance of a large truck using design of experiments. The average of the sum of peak-to-peak roll angles at the first and second part of the double lane is used as an objective function for design of experiments. Six design parameters are selected from all possible parameters affecting on the handling performance. The table of orthogonal arrays is made by 27 times simulations. A computational model of a large truck is developed by MSC/NASTRAN and MSC/ADAMS, and verified the reliability of it with the results of vehicle tests performed in a double lane change course. It is used for the simulations. Analyses of variance and factor effect of the table of orthogonal arrays are performed. This paper proposes an optimal combination of those six design parameters for improving the handling performance of the large truck.