• Smart Structures and Systems
• /
• v.19 no.6
• /
• pp.695-703
• /
• 2017

In this paper, based on first-order shear deformation theory, the governing equations of motion for a sandwich curved beam including an elastic core and two piezo-magnetic face-sheets are presented. The curved beam model is resting on Pasternak's foundation and subjected to applied electric and magnetic potentials on the piezo-magnetic face-sheets and transverse loading. The five equations of motion are analytically solved and the bending and vibration results are obtained. The influence of important parameters of the model such as direct and shear parameters of foundation and applied electric and magnetic potentials are studied on the electro-mechanical responses of the problem. A comparison with literatures was performed to validate our formulation and results.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.794-799
• /
• 2005

Robust DC-DC converter which can cover extensive load changes and also input voltage changes with one controller is needed. In this paper, we propose a method for determining the parameters of 2DOF digital controller which makes the control bandwidth wider, and at the same time makes a variation of the output voltage very small at sudden changes of resistive load and the input voltage. The 2DOF digital controller whose parameters are determined by the proposed method is actually implemented on a DSP and is connected to a DC-DC converter. Experimental studies demonstrate that this type of digital controller can satisfy given specifications.

• Journal of Industrial Technology
• /
• v.24 no.A
• /
• pp.205-214
• /
• 2004

Static reliability models are introduced to analyze the armor stability of rubble-mound breakwaters. Contrasted to the deterministic model, reliability models can estimate the probability of failure directly and calculate the influence of each design variables quantitatively. Thus, it can be possible to design armor units of the rubble-mound breakwaters rationally. In this study FMA(First-order Mean-value Approach), FDA(First-order Design-value Approach) and AFDA(Approximate Full Distribution Approach) of Level II approach of static reliability methods are used to analyze the armor stability of rubble mound breakwaters. The limitations and applications of each approach are studied straight-forwardly.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1992.04a
• /
• pp.134-139
• /
• 1992

This study introduces simple derivation of optimum load factors based on both cornell's MFOSM (Mean First Order End Moment) methods and Lind - Hasofers AFOSM (Advanced First Order 2nd Moment) methods and demonstrates the relationship between the optimum reliability, the load factors, the probability distributions selected to model the load, and a measure of relative failure cost. Although some of the cost parameters cannot be evaluated accurately and the upper tail characteristics of the distributions of the random loads remain uncertainty, this optimum reliability formulation provides insight on which Parameters are most significant in selecting appropriate load criteria for structure design.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.16 no.2
• /
• pp.169-180
• /
• 1992

The purpose of this study is to investigate the effects of type of clothing microclimate and exercise condition on ventilation. The experimental system employed a trace gas technique of the previous research. Clothing microclimate volume measurement was based on the substitution water technique for inter-clothing air volume. The experimental variables were tested at four levels of clothing microclimate spacing, microclimate shape of the previous research and two levels of exercise conditions. 2, 4, 6 cm ease were added to B/2+4 of basic blouse pattern for the microclimate spacing variable. Each combination of three variables were tested in triplicate. Analysis of variance of experimental variables on vetilation, such as oxygen exchange rate, half time of first order model was conducted. Oxygen exchange rate and half time of first order model are affected by the shape of microclimate air and exercise condition.

• Advances in nano research
• /
• v.4 no.4
• /
• pp.309-326
• /
• 2016

The buckling response of a single-layered graphene sheet (SLGS) embedded in visco-Pasternak's medium is presented. The nonlocal first-order shear deformation elasticity theory is used for this purpose. The visco-Pasternak's medium is considered by adding the damping effect to the usual foundation model which characterized by the linear Winkler's modulus and Pasternak's (shear) foundation modulus. The SLGS be subjected to distributive compressive in-plane edge forces per unit length. The governing equilibrium equations are obtained and solved for getting the critical buckling loads of simply-supported SLGSs. The effects of many parameters like nonlocal parameter, aspect ratio, Winkler-Pasternak's foundation, damping coefficient, and mode numbers on the buckling analysis of the SLGSs are investigated in detail. The present results are compared with the corresponding available in the literature. Additional results are tabulated and plotted for sensing the effect of all used parameters and to investigate the visco-Pasternak's parameters for future comparisons.

• Journal of Korean Institute of Industrial Engineers
• /
• v.14 no.2
• /
• pp.53-61
• /
• 1988

Games such as baseball, soccer are scheduled by a given game type such as tournament, league or their mixed form. The objective of this paper is to find an efficient game-scheduling method with respect to traveling distance, break-time and other conditions. In this paper we first present two models which minimize traveling distance. The first model that a match is played once each other is solved by a heuristic method. In the second model that a match is played more than once, teams are paired by a modified 0 - 1 programming, and the pairs are rearranged in order to generate a number of workable schedules. Then Expert Systems is applied to solve breake-time and other conditions. In order to represent expertise's knowledge effectively, we present a new design of knowledge-base and data-base, inference engine including many rules and meta-rules which controls the global system. In knowledge-base, binary relation among various attributes is used to ease not only knowledge acquisition but also system execution.

• Geomechanics and Engineering
• /
• v.2 no.1
• /
• pp.57-69
• /
• 2010

A major consideration in the design of tunnels in urban areas is the prediction of the ground movements and surface settlements associated with the tunneling operations. Excessive ground movements can damage adjacent building and utilities. In this paper, a neural network model is used to predict the maximum surface settlement, based on instrumented results from three separate EPB tunneling projects in Singapore. This paper demonstrates that by coupling the trained neural network model to a spreadsheet optimization technique, the reliability assessment of the settlement serviceability limit state can be carried out using the first-order reliability method. With this method, it is possible to carry out sensitivity studies to examine the effect of the level of uncertainty of each parameter uncertainty on the probability that the serviceability limit state has been exceeded.

• International Journal of Computer Science & Network Security
• /
• v.21 no.6
• /
• pp.200-206
• /
• 2021

Fraud in e-commerce transaction increased in the last decade especially with the increasing number of online stores and the lockdown that forced more people to pay for services and groceries online using their credit card. Several machine learning methods were proposed to detect fraudulent transaction. Neural networks showed promising results, but it has some few drawbacks that can be overcome using optimization methods. There are two categories of learning optimization methods, first-order methods which utilizes gradient information to construct the next training iteration whereas, and second-order methods which derivatives use Hessian to calculate the iteration based on the optimization trajectory. There also some training refinements procedures that aims to potentially enhance the original accuracy while possibly reduce the model size. This paper investigate the performance of several NN models in detecting fraud in e-commerce transaction. The backpropagation model which is classified as first learning algorithm achieved the best accuracy 96% among all the models.

• Progress in Superconductivity and Cryogenics
• /
• v.8 no.3
• /
• pp.63-69
• /
• 2006

This paper describes the effect of rotating frequency on the pulse tube of Stirling type pulse tube refrigerator. Various conditions were analyzed by two-dimensional analysis with several dominant non-dimensional parameters. With the additional pressure term influenced by centrifugal force in rotating condition, the linearized conservation equations of mass, momentum, energy of the gas were solved to obtain the first order variables and calculate the enthalpy flow in rectangular coordinates. The rotational effect in pulse tube for the refrigerator's performance were quantitatively evaluated. According to the first order analysis, the enthalpy flow decreases with the rotating speed.