• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 1993.06a
• /
• pp.1094-1097
• /
• 1993

In this paper, the absolute stability criterion of nonlinear plants with sector bounded nonlinear feedback is derived. The result obtained is useful for applications, in particular, stability analysis and design of fuzzy logic controllers.

• Structural Engineering and Mechanics
• /
• v.62 no.2
• /
• pp.209-224
• /
• 2017

Elevated water tanks are considered as important structures due to its post-earthquake requirements. Elevated water tank on reinforced concrete frame staging is widely used in India. Different response reduction factors depending on ductility of frame members are used in seismic design of frame staging. The study on appropriateness of response reduction factor for reinforced concrete tank staging is sparse in literature. In the present paper a systematic study on estimation of key components of response reduction factors is presented. By considering the various combinations of tank capacity, height of staging, seismic design level and design response reduction factors, forty-eight analytical models are developed and designed using relevant Indian codes. The minimum specified design cross section of column as per Indian code is found to be sufficient to accommodate the design steel. The strength factor and ductility factor are estimated using results of nonlinear static pushover analysis. It was observed that for seismic design category 'high' the strength factor has lesser contribution than ductility factor, whereas, opposite trend is observed for seismic design category 'low'. Further, the effects of staging height and tank capacity on strength and ductility factors for two different seismic design categories are studied. For both seismic design categories, the response reduction factors obtained from the nonlinear static analysis is higher than the code specified response reduction factors. The minimum dimension restriction of column is observed as key parameter in achieving the desired performance of the elevated water tank on frame staging.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.15 no.2
• /
• pp.126-131
• /
• 2015

Studies on the control of inverted pendulum type systems have been widely reported. This is because this type of system is a typical complex nonlinear system and may be a good model to verify the performance of a proposed control system. In this paper, we propose the design of two fuzzy logic control systems for the control of a Segway mobile robot which is an inverted pendulum type system. We first introduce a dynamic model of the Segway mobile robot and then analyze the system. We then propose the design of the fuzzy logic control system, which shows good performance for the control of any nonlinear system. In this paper, we here design two fuzzy logic control systems for the position and balance control of the Segway mobile robot. We demonstrate their usefulness through simulation examples. We also note the possibility of simplifying the design process and reducing the computational complexity. This possibility is the result of the skew symmetric property of the fuzzy rule tables of the system.

• Proceedings of the KSME Conference
• /
• 2001.06c
• /
• pp.420-425
• /
• 2001

The information content is determined by establishing the system range for each of the FRs and by determing the overlap between system range and the design range (i.e the designer-specified range). However, conventional information content doesn't include designer's intention sufficiently. In this paper, the satisfaction function is presented to embody designer's intention by calculating information contents. The satisfaction function is created in order to deal with the uncertanties involved in determining the design range and the system range in terms of a given physical parameter. So, the satisfaction function help designer to choose the optimal design among many proposed design.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.12 no.6
• /
• pp.71-76
• /
• 2003

Optimal design of panel with trapezoidal type stiffeners was studied using linear and nonlinear deformation theories. Also analysis method was using closed-form analysis and finite difference energy methods, respectively. Various bucking load factors are obatined for stiffened laminated composite panel with trapezoidal type stiffeners and various aspect ratios, which are made from Carbon/Epoxy USN 125 prepreg and are simply-supported on four edges under uniaxial compression. Optimal design analyses are carried out by the nonlinear search optimizer, ADS.

• Journal of Mechanical Science and Technology
• /
• v.17 no.12
• /
• pp.1938-1948
• /
• 2003

This paper represents that an enhanced genetic algorithm (EGA) is applied to optimal design of a squeeze film damper (SFD) to minimize the maximum transmitted load between the bearing and foundation in the operational speed range. A general genetic algorithm (GA) is well known as a useful global optimization technique for complex and nonlinear optimization problems. The EGA consists of the GA to optimize multi-modal functions and the simplex method to search intensively the candidate solutions by the GA for optimal solutions. The performance of the EGA with a benchmark function is compared to them by the IGA (Immune-Genetic Algorithm) and SQP (Sequential Quadratic Programming). The radius, length and radial clearance of the SFD are defined as the design parameters. The objective function is the minimization of a maximum transmitted load of a flexible rotor system with the nonlinear SFDs in the operating speed range. The effectiveness of the EGA for the optimal design of the SFD is discussed from a numerical example.

• Journal of Sensor Science and Technology
• /
• v.5 no.4
• /
• pp.81-87
• /
• 1996

This paper presents the optimal design method of SAW filters with arbitrary frequency characteristics. The design program using the unconstrained nonlinear optimization method and FFT algorithm is developed for optimal design of SAW filters with arbitrary frequency characteristics. As a design example, a SAW TV IF filter with asymmetric-amplitude and nonlinear-phase frequency characteristics is designed.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.501-506
• /
• 2000

An iterative numerical computational algorithm is presented to design a plate or shell element subjected to membrane and flexural forces. Based on equilibrium consideration, equations for capacities of top and bottom reinforcements in two orthogonal directions have been derived. The amount of reinforcement is determined locally, i.e., for each sampling point, from the equilibrium between applied and internal forces. Based on nonlinear analyses performed in a hyperbolic cooling tower, the analytically calculated ultimate load exceeded the design ultimate load from 50% to 55% for an analysis with relatively low to high tension stiffening, cases $\gamma$=10 and 15. For these cases, the design method gives a lower bound on the ultimate load with respect to Lower bound theorem, This shows the adequacy of th current practice at least for this cooling tower shell case studied. To generalize the conclusion more designs - analyses should be reformed with different shell configurations.

• Journal of Ocean Engineering and Technology
• /
• v.34 no.2
• /
• pp.97-109
• /
• 2020

In this study, ultimate strength characteristics of clamped sandwich panels with metal faces and an elastic isotropic core under combined in-plane compression and lateral pressure loads are investigated to verify the applicability of the ultimate strength design formula for ship structures. Alternative elastomer-cored steel sandwich panels are selected instead of the conventional bottom stiffened panels for a Suezmax-class tanker and then the ultimate strength characteristics of the selected sandwich panels are examined by using nonlinear finite element analysis. The change in the ultimate strength characteristics due to the change in the thickness of the face plate and core as well as the amplitude of lateral pressure are summarized and compared with the results obtained by using the ultimate strength design formula and nonlinear finite element analysis. The insights and conclusions developed in the present study will be useful for the design and development of applications for sandwich panels in double hull tanker structures.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.15 no.2
• /
• pp.10-15
• /
• 2006

The optimal design for stiffened laminated composite cylindrical panels under axial compression was studied using linear and nonlinear deformation theories by finite difference energy methods. Various panel structures was made from Carbon/Epoxy USN125 prepreg and considered 3 types stiffeners. Optimal design analyses of panel structure are carried out by the nonlinear search optimizer, ADS. This optimal design results are compared to the FEM result using ANSYS.