• Steel and Composite Structures
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• v.15 no.6
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• pp.659-677
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• 2013

This paper introduces new specimens of Steel-Carbon Fibre Reinforced Polymer composite developed in accordance with standard test method and definition for mechanical testing of steel (ASTM-A370). The main purpose of this research is to study the behaviour of steel-CFRP composite specimen under uniaxial tension to use it in beams in lieu of traditional steel bar reinforcement. Eighteen specimens were prepared and divided into six groups, depending upon the number of the layers of CFRP. Uniaxial tensile tests were conducted to determine yield strength and ultimate strength of specimens. Test results showed that the stress-strain curve of the composite specimen was bilinear prior to the fracture of CFRP laminate. The tested composite specimens displayed a large difference in strength with remarkable ductility. The ultimate load for Steel-Carbon Fibre Reinforced Polymer composite specimens was found using the model proposed by Wu et al. (2010) and nonlinear FE analysis. The ultimate loads obtained from FE analysis are found to be in good agreement with experimental ones. However, ultimate loads obtained applying Wu model are significantly different from experimental/FE ones. This suggested modification of Wu model. Modified Wu's model which gives a better estimate for the ultimate load of Steel-Carbon Fibre Reinforced Polymer (SCFRP) composite specimen is presented in this paper.

• Earthquakes and Structures
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• v.10 no.1
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• pp.1-23
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• 2016

Steel plate shear walls (SPSWs) have been shown to be efficient lateral force-resisting systems, which are increasingly used in new and retrofit construction. These structural systems are designed with either stiffened and stocky or unstiffened and slender web plates based on disparate structural and economical considerations. Based on some limited reported studies, on the other hand, employment of low yield point (LYP) steel infill plates with extremely low yield strength, and high ductility as well as elongation properties is found to facilitate the design and improve the structural behavior and seismic performance of the SPSW systems. On this basis, this paper reports system-level investigations on the seismic response assessment of multi-story SPSW frames under the action of earthquake ground motions. The effectiveness of the strip model in representing the behaviors of SPSWs with different buckling and yielding properties is primarily verified. Subsequently, the structural and seismic performances of several code-designed and retrofitted SPSW frames with conventional and LYP steel infill plates are investigated through detailed modal and nonlinear time-history analyses. Evaluation of various seismic response parameters including drift, acceleration, base shear and moment, column axial load, and web-plate ductility demands, demonstrates the capabilities of SPSW systems in improving the seismic performance of structures and reveals various advantages of use of LYP steel material in seismic design and retrofit of SPSW systems, in particular, application of LYP steel infill plates of double thickness in seismic retrofit of conventional steel and code-designed SPSW frames.

• Corrosion Science and Technology
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• v.23 no.3
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• pp.228-234
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• 2024

Zinc wiping is a phenomenon used to control zinc-coating thickness on steel substrate during hot dip galvanizing by equipment called air knife. Uniformity of zinc coating weight in length and width profile along with surface quality are most critical quality parameters of galvanized steel. Deviation from tolerance level of coating thickness causes issues like overcoating (excess consumption of costly zinc) or undercoating leading to rejections due to non-compliance of customer requirement. Main contributor of deviation from target coating weight is dynamic change in air knives equipment setup when thickness, width, and type of substrate changes. Additionally, cold coating measurement gauge measure coating weight after solidification but are installed down the line from air knife resulting in delayed feedback. This study presents a coating weight control model (Galvantage) predicting critical air knife parameters air pressure, knife distance from strip and line speed for coating control. A reverse engineering approach is adopted to design a predictive, prescriptive, and descriptive model recommending air knife setups that estimate air knife distance and expected coating weight in real time. Implementation of this model eliminates feedback lag experienced due to location of coating gauge and achieving setup without trial-error by operator.

• Structural Engineering and Mechanics
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• v.84 no.1
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• pp.113-127
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• 2022

Steel plate shear walls (SPSWs) are commonly utilized to provide lateral stiffness in high-rise structures. The simplified model is frequently used instead of the fine-scale model in the design of buildings with SPSWs. To predict the lateral strength of steel plate shear walls with diagonal stiffeners (DS-SPSWs), a simplified model is presented, namely the cross brace-strip model (CBSM). The bearing capacity and internal forces of columns for DS-SPSWs are calculated. In addition, a modification coefficient is introduced to account for the shear action of the thin plate. The feasibility of the CBSM is validated by comparing the numerical results with theoretical and experimental results. The numerical results from the CBSM and fine-scale model, which represent the bearing capacity of the DS-SPSW with varied stiffened plate dimensions, are in good accord with the theoretical values. The difference in bearing capacity between the CBSM and the fine-scale model is less than 1.35%. The errors of the bearing capacity from the CBSM are less than 5.67% when compared to the test results of the DS-SPSW. Furthermore, the shear and axial forces of CBSM agree with the results of the fine-scale model and theoretical analysis. As a result, the CBSM, which reflects the contribution of diagonal stiffeners to the lateral resistance of the SPSW as well as the effects on the shear and axial forces of the columns, can significantly improve the design accuracy and efficiency of buildings with DS-SPSWs.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.4 s.193
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• pp.76-83
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• 2007

A new neural network classifier is proposed for the automatic real-time surface inspection of high-speed cold steel strips having 11 different types of defects. 46 geometrical and gray-level features are extracted for the defect classification. 3241 samples of Posco's Kwangyang steel factory are used for training and testing the neural network classifier. The developed classifier produces plausible 15% error rate which is much better than 20-30% error rate of human vision inspection adopted in most of domestic steel factories.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.4
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• pp.247-252
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• 2016

In this paper, we propose a new defect detection technology for micro-defect on the surface of steel products. Due to depth and size of microscopic defect, slop of surface and vibration of strip, the conventional optical method cannot guarantee the detection performance. To solve the above-mentioned problems and increase signal to noise ratio, a novel retro-schlieren method that consists of retro reflector and knife edge is proposed. Moreover dual switching lighting method is also applied to distinguish uneven micro defects and surface noise. In proposed method, defective regions are represented by a black and white pattern. This pattern is detected by a defect detection algorithm with Gabor filter. Experimental results by simulator for sample defects of cold rolled steel show that the proposed method is effective.

• Steel and Composite Structures
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• v.18 no.3
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• pp.711-737
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• 2015

Steel Plate Shear Walls (SPSWs) have been accepted widely as an effective lateral load resisting system. For seismic performance evaluation of a multi-story building with SPSWs, detailed finite element models or a strip model can be used to represent the SPSW components. However, such models often require significant effort for tall or medium height buildings. In order to simplify the analysis process, discrete elements for the framing members can be used. This paper presents development of a simplified equivalent braced model to study the behavior of the SPSWs. The proposed model is expected to facilitate a simplification to the structural modeling of large buildings with SPSWs in order to evaluate the seismic performance using regular structural analysis tools. It is observed that the proposed model can capture the global behavior of the structures quite accurately and potentially aid in the performance-based seismic design of SPSW buildings.

• Journal of Korea Foundry Society
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• v.24 no.1
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• pp.26-33
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• 2004

The pressure of the mold flux acting on the meniscus shell was investigated through the coupling analysis of heat transfer in the mold and fluid flow in the flux caused by the mold oscillation. Finite element method was employed to solve the conservation equation associated with appropriate boundary conditions. As reported by previous workers, the axial pressure is positive on the negative strip time and negative on the positive strip time. A maximum pressure is predicted toward the top of the meniscus shell which has the thin shell arid a maximum value is in proportion to the relative mold oscillation velocity. The relative mold oscillation velocity was changed by the effect of meniscus level fluctuation. Therefore the pressure of the mold flux acting on the meniscus shell was different each cycle of the mold oscillation due to the irregularity of relative mold oscillation velocity.

• Transactions of Materials Processing
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• v.8 no.1
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• pp.65-77
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• 1999

In recent years, the quality requirements from the customers of hot rolled steel strip have been steadily increasing in diversity and strictness. To meet these quality requirements as well as to improve productivity, steel mills have been doing their efforts for developing high performance Automatic Gauge Control (AGC) system. However, it is very time consuming and also needs a lot of money to develop the new technologies of AGC in actual mill. So, there has been a demand for developing the Dynamic Hot Rolling Simulator since late 80's. It is a kind of software packages and can analyze the dynamic behaviors of hot finishing rolling process without laborious experiments in actual mill. It can also be used as a designing tool of Automatic Gauge Controller. In this work, the Dynamic Hot Rolling Simulator which is applicable to 6 sands hot strip mill rolling was developed. The MATLAB with SIMLINK was used as a software developer for making the main part of simulator because it is very powerful tool for modeling, integrating, controller design, and simulation. In this paper, the structures and the mathematical models of the simulator were briefly described and the results of simulation on the transient phenomena of hot rolling process with actual mill data were also presented.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.229-232
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• 2003

In the roll forming process, a sheet or strip of metal is continuously and progressively formed into a desired cross-sectional profile by feeding it through a series of forming roll. Accordingly, it is important to maintain the material properties of the initial sheet and deform uniformly during the roll forming. The roll forming process was estimated in consideration of some factors such as material properties, strip thickness, roll diameter, roll velocity, and the deformation of the material that influence the forming length. The hydroforming technology has been recognized as a new technique in manufacturing industry, especially in automotive industry. The formed pipe in used in hydroforming process is manufactured by the roll forming. The formability during hydroforming is very sensitive to the state of pipes which are made by roll forming. Particularly the amount of hardening during roll forming affects the formability. Therefore, it is necessary to design the optimum roll flower to reduce the local hardening. In this paper, optimum roll flower which has uniform strain distribution through sheet width was obtained by comparing strain distribution in various roll flower. Finite element analysis(FEA) is performed to estimate the strain distribution related to hardening by roll forming. A numerical analysis is carried out by SHAPE-RF.