• Computers and Concrete
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• v.3 no.5
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• pp.313-334
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• 2006

A novel formulation aiming to achieve optimal design of reinforced concrete (RC) structures is presented here. Optimal sizing and reinforcing for beam and column members in multi-bay and multistory RC structures incorporates optimal stiffness correlation among all structural members and results in cost savings over typical-practice design solutions. A Nonlinear Programming algorithm searches for a minimum cost solution that satisfies ACI 2005 code requirements for axial and flexural loads. Material and labor costs for forming and placing concrete and steel are incorporated as a function of member size using RS Means 2005 cost data. Successful implementation demonstrates the abilities and performance of MATLAB's (The Mathworks, Inc.) Sequential Quadratic Programming algorithm for the design optimization of RC structures. A number of examples are presented that demonstrate the ability of this formulation to achieve optimal designs.

• Journal of the Earthquake Engineering Society of Korea
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• v.23 no.2
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• pp.109-117
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• 2019

In this study, a design procedure for the practical application of the dampers to building structures under earthquake loads was presented by using earthquake response spectrum. Nonlinear time history results using a 10 story building structure installed with damper verified the effectiveness of the proposed procedure by showing that the structural response could be reduced to the target performance level for seismic loads. Since the proposed design procedures are based on response spectrum seismic analysis result of the original structure, the capacity, location and the number of damper and the consequent response reduction effects can be preliminarily determined without performing the nonlinear time history analysis.

• Smart Structures and Systems
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• v.30 no.6
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• pp.627-637
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• 2022

Recent years, direct displacement-based design (DDBD) procedure is proposed for the design of un-bonded posttensioned (UPT) concrete wall systems. In the DDBD procedure, the determination of the equivalent viscous damping (EVD) ratio is critical since it would influence the strength demand of the UPT wall systems. Nevertheless, the influence of EVD ratio determination of the UPT wall systems were not thoroughly evaluated. This study was aimed to investigate the influence of different EVD ratio determinations on the DDBD procedure of UPT wall systems. Case study structures with four, twelve and twenty storeys have been designed with DDBD procedure considering different EVD ratio determinations. Nonlinear time history analysis was performed to validate the design results of those UPT wall systems. And the simulation results showed that the global responses of the case study structures were influenced by the EVD ratio determination.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.408-413
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• 2004

High speed planning boats also have been required more and more the rational strength analysis and evaluation for the optimal structural design in respect of the structural lightness according to the high speed trend. Even though the suggestion of the simple type equation for the equivalent dynamic pressure is reasonable to design the scantling of ship structure conveniently, many research activities for more reasonable improvement of the simple design pressure, have been continued to suggest the more accurate equivalent static description of tire structural response such as the deflection and stress of hull structure. In this research, we focus on the aluminum bottom stiffened plate structure in which structural scantling is mainly depend on the local loads such as dynamic or impact pressure without other load effects and structural response for the simple dynamic equivalent pressure was investigated through the structural analysis. In order to investigate the structural response of the bottom stiffened plate structure subjected to the dynamic equivalent design pressure, linear and nonlinear structural analysis of the bottom stiffened plate structure of 4.3 ton aluminum planning boat was performed based on the equivalent static applied loads which were derived from the KR regulation and representative one among various dynamic equivalent pressure equations. From above analysis results, we found that the response such as deflection and stress of plate member was similar with the response results of one plate member model with fixed boundary, which was published previous paper and in case of KR design loading, all response of stiffened plate structure were within elastic limit. Through the nonlinear analysis, nearly elastic behavior including the slight geometrical nonlinear response was dominant but plastic local zone was appeared at $85\%$ limit load. Therefore, we can say that through tire linear and nonlinear analysis, this stiffened plate member has no structural strength problem based on the yield criteria in case within $60\%$ limit load except the other strength point of view such as the fatigue and buckling problem.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.2
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• pp.185-189
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• 2007

This paper deals with a fault detection system design for nonlinear systems with uncertain time varying parameters modelled as a T-S fuzzy system. A coprime factorization for T-S fuzzy systems is defined and a residual generator is designed using a left coprime factor. A fault detection criteria derived from the residual generator is also suggested. In order to demonstrate the efficacy of the suggested method, the fault defection method is applied to an inverted pendulum system and computer simulations are performed.

• Journal of Power Electronics
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• v.15 no.3
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• pp.763-774
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• 2015

This study investigates the inherent influence of a DC-link voltage controller on both DC-link voltage control and the compensation performance of a three-phase, four-wire shunt active power filter (APF). A nonlinear variable-parameter DC-link voltage controller is proposed to satisfy both the dynamic characteristic of DC-link voltage control and steady-state compensation performance. Unlike in the conventional fixed-parameter controller, the parameters in the proposed controller vary according to the difference between the actual and the reference DC-link voltages. The design procedures for the nonlinear voltage controller with variable parameters are determined and analyzed so that the proposed voltage controller can be designed accordingly. Representative simulation and experimental results for the three-phase, four-wire, center-spilt shunt APF verify the analysis findings, as well as the feasibility and effectiveness of the proposed DC-link voltage controller.

• International Journal of Control, Automation, and Systems
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• v.2 no.1
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• pp.76-82
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• 2004

A robust fuzzy controller is designed to stabilize a class of solvable nonlinear descriptor systems with time-varying delay. First, a new modeling and control method for nonlinear descriptor systems is presented with a fuzzy descriptor model. A sufficient condition for the existence of the fuzzy controller is given in terms of a series of LMIs. Then, a less conservative fuzzy controller design approach is obtained based on the fuzzy rules and weights. This method includes the interactions of the different subsystems into one matrix. The effectiveness of the presented approach and the design procedure of the fuzzy controller are illustrated by way of an example.

• International Journal of Control, Automation, and Systems
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• v.4 no.2
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• pp.146-154
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• 2006

In this paper, we propose direct and indirect adaptive fuzzy sliding mode control approaches for a class of nonaffine nonlinear systems. In the direct case, we use the implicit function theory to prove the existence of an ideal implicit feedback linearization controller, and hence approximate it to attain the desired performances. In the indirect case, we exploit the linear structure of a Takagi-Sugeno fuzzy system with constant conclusion to establish an affine-in-control model, and therefore design an indirect adaptive fuzzy controller. In both cases, the adaptation laws of the adjustable parameters are deduced from the stability analysis, in the sense of Lyapunov, to get a more accurate approximation level. In addition to their robustness, the design of the proposed approaches does not require the upper bounds of both external disturbances and approximation errors. To show the efficiency of the proposed controllers, a simulation example is presented.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.12-19
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• 2005

The single layer latticed dome is very sensitive on the slenderness ratio and half open angle of the elements, load condition and the connection type because it is organized by a lot of thin elements, so we have to use the geometrically nonlinear buckling load when the buckling behavior of the structures is analyzed But, it is very difficult to design the single layer latticed domes considered all conditions. Therefore the purpose of this paper is to propose the appropriate design method of the single layer latticed dome considered the geometrically nonlinear buckling load in base on the linear buckling load by the eigen-value analysis.

• Journal of the Korean Society of Industry Convergence
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• v.18 no.2
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• pp.67-74
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• 2015

Two-wheeled driying mobild robots are precise controlled in terms of linear contol methods without considering the nonlinear dynamical characteristics. However, in the high maneuvering situations such as fast turn and abrupt start and stop, such neglected terms become dominant and heavy influence the overall driving performance. This study describes the nonlinear optimal control method to take advantage of the exact nonlinear dynamics of the balancing robot. Simulation results indicate that the optimal control outperforms in the respect of transient performance and required wheel torques. A design example is suggested for the state matrix that provides design flexibility in the control. It is shown that a well-planned state matrix by reflecting the physics of a balancing robot greatly conrtibutes to the driving performance and stability.