• Smart Structures and Systems
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• v.15 no.3
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• pp.897-911
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• 2015

This study presents a novel approach based on advancements in Evolutionary Computation for data-driven modeling of complex multi-dimensional memory-dependent systems. The investigated example is a benchmark coupled three-dimensional system that incorporates 6 Bouc-Wen elements, and is subjected to external excitations at three points. The proposed technique of this research adapts Genetic Programming for discovering the optimum structure of the differential equation of an auxiliary variable associated with every specific degree-of-freedom of this system that integrates the imposed effect of vibrations at all other degrees-of-freedom. After the termination of the first phase of the optimization process, a system of differential equations is formed that represent the multi-dimensional hysteretic system. Then, the parameters of this system of differential equations are optimized in the second phase using Genetic Algorithms to yield accurate response estimates globally, because the separately obtained differential equations are coupled essentially, and their true performance can be assessed only when the entire system of coupled differential equations is solved. The resultant model after the second phase of optimization is a low-order low-complexity surrogate computational model that represents the investigated three-dimensional memory-dependent system. Hence, this research presents a promising data-driven modeling technique for obtaining optimized representative models for multi-dimensional hysteretic systems that yield reasonably accurate results, and can be generalized to many problems, in various fields, ranging from engineering to economics as well as biology.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.58
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• pp.287-311
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• 2013

In this study, the scope of previous logistics security were focused only on port and ship. Because of it now extends to the overall (export and import) supply chain areas and in regards with supply security programs in the international level, it reviewed supply chain security programs categorized them into 'ships and port security system', 'container screening system', 'logistics chain authorization system' which are expanded to be adopted in the international level. The major features of those programs are summarized as in building risk management system, providing information ahead, selectivity test and benefits to AEO authorized companies in the customs administration level. The government and companies which are to ensure supply chain security and trade facilitation in order to cope actively with international customs administrative atmosphere need to do the followings : First, they need to build an intra-government integrated supply chain security and make efforts to conclude AEO MRA in order to increase trade competitiveness among major trading countries. Second, they need to build supply chain risk management system in order to enhance management performance through overseas market and company level strategy to obtain and maintain AEO authorization in the company level.

• International Journal of Automotive Technology
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• v.7 no.5
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• pp.535-545
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• 2006

A nonlinear analysis of torsional self-excited vibration in the driveline system for wheeled towing tractors was presented, with a 2-DOF mathematical model. The vibration system was described as a second-order ordinary differential equation. An analytical approach was proposed to the solution of the second-order ODE. The mathematical neighborhood concept was used to construct the interior boundary and the exterior boundary. The ODE was proved to have a limit cycle by using $Poincar\'{e}-Bendixson$ Annulus Theorem when two inequalities were satisfied. Because the two inequalities are easily satisfied, the self-excited vibration is inevitable and even the initial slip rate is little. However, the amplitude will be almost zero when the third inequality is satisfied. Only in a few working modes of the towing tractor the third inequality is not satisfied. It is shown by experiments that the torsional self-excited vibration in the driveline of the vehicle is obvious.

• Steel and Composite Structures
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• v.2 no.3
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• pp.209-222
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• 2002

This paper describes the buckling phenomenon of a tubular truss with unsupported length through a full-scale test and presents a practical computational method for the design of the trusses allowing for the contribution of torsional stiffness against buckling, of which the effect has never been considered previously by others. The current practice for the design of a planar truss has largely been based on the linear elastic approach which cannot allow for the contribution of torsional stiffness and tension members in a structural system against buckling. The over-simplified analytical technique is unable to provide a realistic and an economical design to a structure. In this paper the stability theory is applied to the second-order analysis and design of the structural form, with detailed allowance for the instability and second-order effects in compliance with design code requirements. Finally, the paper demonstrates the application of the proposed method to the stability design of a commonly adopted truss system used in support of glass panels in which lateral bracing members are highly undesirable for economical and aesthetic reasons.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.2
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• pp.49-55
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• 2000

In this paper, we show that our previously proposed second-order iterative learning control method with feedback is more effective and has better convergence performance than the second-order iterative learning control method without feedback, particularly in the case of the existence of initial condition errors. Also the convergence proof of the proposed method is given. And through the simulation result of applying the proposed method to the linear time-varying system, we show that our proposed method has enhanced robustness and stability in case of the existence of initial condition errors.

• Journal of computational fluids engineering
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• v.2 no.1
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• pp.46-53
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• 1997

The flow field around a three dimensional minivan-like body has been simulated. This study solves 3-D unsteady incompressible Navier-Stokes equations on a non-orthogonal curvilinear coordinate system using second-order accurate schemes for the time derivatives, and third/second-order scheme for the spatial derivatives. The Marker-and-Cell concept is applied to efficiently solve continuity equation. A H-H type of multi-block grid system is generated around a three dimensional minivan-like body. Turbulent flows have been modeled by the Baldwin-Lomax turbulent model. To validate present procedure, the flows around the Ahmed body with 12.5° of slant angle are simulated. A good agreement with other numerical results is achived. After code validation, the flows around a mimivan-like body are simulated. The simulation shows three dimensional vortex-pair just behind body. The flow separation is also observed on the rear of the body. It has concluded that the results of present study properly agreed with physical flow phenomena.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2000.05a
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• pp.322-328
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• 2000

This study discusses cognition as a computable mapping in cognitive system and relates G del's Incompleteness Theorems to the computability of cognition from a metamathematical perspective. Understanding cognition as a from of computation requires not only Turing machine models but also neural network models. In previous studies of computation by cognitive systems, it is remarkable to note how little serious attention has been given to the issue of computation by neural networks with respect to G del's Incompleteness Theorems. To address this problem, first, we introduce a definition of cognition and cognitive science. Second, we deal with G del's view of computability, incompleteness and speed-up theorems, and then we interpret G del's disjunction on the mind and the machine. Third, we discuss cognition as a Turing computable function and its relation to G del's incompleteness. Finally, we investigate cognition as a neural computable function and its relation to G del's incompleteness. The results show that a second-order representing system can be implemented by a finite recurrent neural network. Hence one cannot prove the consistency of such neural networks in terms of first-order theories. Neural computability, theoretically, is beyond the computational incompleteness of Turing machines. If cognition is a neural computable function, then G del's incompleteness result does not limit the compytational capability of cognition in humans or in artifacts.

• Nuclear Engineering and Technology
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• v.41 no.7
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• pp.885-892
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• 2009

This manuscript will discuss a numerical method where the six equations of two-phase flow, the solid heat conduction equations, and the two equations that describe neutron diffusion and precursor concentration are solved together in a tightly coupled, nonlinear fashion for a simplified model of a nuclear reactor core. This approach has two important advantages. The first advantage is a higher level of accuracy. Because the equations are solved together in a single nonlinear system, the solution is more accurate than the traditional "operator split" approach where the two-phase flow equations are solved first, the heat conduction is solved second and the neutron diffusion is solved third, limiting the temporal accuracy to $1^{st}$ order because the nonlinear coupling between the physics is handled explicitly. The second advantage of the method described in this manuscript is that the time step control in the fully implicit system can be based on the timescale of the solution rather than a stability-based time step restriction like the material Courant limit required of operator-split methods. In this work, a pilot code was used which employs this tightly coupled, fully implicit method to simulate a reactor core. Results are presented from a simulated control rod movement which show $2^{nd}$ order accuracy in time. Also described in this paper is a simulated rod ejection demonstrating how the fastest timescale of the problem can change between the state variables of neutronics, conduction and two-phase flow during the course of a transient.

• Asia pacific journal of information systems
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• v.13 no.3
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• pp.173-193
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• 2003

As the interest in the business-to-business(B2B) electronic commerce is increasing, some companies are participating in the B2B eMarketplaces(electronic marketplaces). The eMarketplace has an effect on the method of B2B transactions or the purchasing performance. The academy and the industry are focused on the cause and the result of this effect. The purpose of this research is to analyze the effects of the relational exchange with eMarketplace on the purchasing performance, considering the supply externality and system integration as intervening variables. This study investigates the second-order effect of eMarketplace in which the degree of improvements in two aspects of purchasing activity(price reduction, purchasing efficiency) depends on the degree of the relational exchange with eMarketplace, namely, the governance of eMarketplace. Our hypotheses on this second order effect were supported. We found that the higher the relational governance, the lower in price reduction, and the better in purchasing efficiency. In more details, the high relational governance lowers the supply externality, and in turn deteriorates the improvement in price reduction. Meanwhile, the high relational governance accelerates the information system integration, and brings the better purchasing efficiency. Our findings suggest that organizations can improve their purchasing activities better if they choose the appropriate eMarketplace governance.

• Journal of the Korean Chemical Society
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• v.17 no.4
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• pp.298-305
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• 1973

Following results were obtained for the mechanical degradation of polystyrene (for polystyrene itself and when blended with rubber) by roll mastication. 1) The rate of mechanical degradation for polystyrene itself can be represented by the second-order rate equation proposed by Goto. $-\frac{dP_t}{dt} = k_s(P_t-P_{\infty})^2$ Where Pt is the degree of polymerization of the degraded polymer at t minutes and $P{\infty}$ is the final degree of polymerization. 2) The mechanical degradation of polystyrene component in the polystyrene-rubber (SBR, BR) blend system occurred similarly as that of polystyrene itself. 3) Under the experimental conditions the mechanical degradation rate of the polystyrene component of the polystyrene-rubber, (SBR, BR) blend system followed approximately the same second-order equation as that for polystyrene itself.