• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.3
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• pp.553-561
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• 2001

Chua's oscillator is a simple electronic circuit which exhibits a variety of bifurcation phenomena and attractors, It consist of two capacitors, an inductor, two linear resistors, and a nonlinear resistor. When the circuit exhibits chaotic signals, the nonlinear resistor of Chua's oscillator may have six different voltage - current characteristics. In this paper, the design methodology for practical implementation of the nonlinear resistors which have all these characteristics is described. In addition, the effectivness of result is shown by not only the computer simulation but also the experimental test.

• Journal of Ocean Engineering and Technology
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• v.19 no.4 s.65
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• pp.1-8
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• 2005

A nonlinear time-domain strip theory for vertical wave loads and ship responses is to be investigated. The hydrodynamic memory effect is approximated by a higher order differential equation without convolution. The ship is modeled as a non-uniform Timoshenko beam. Numerical calculations are presented for the S175 Containership translating with the forward speed in regular waves. The approach described in this paper can be used in evaluating ship motions and wave loads in extreme wave conditions and validating nonlinear phenomena in ship design.

• Journal of applied mathematics & informatics
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• v.5 no.3
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• pp.615-632
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• 1998

Soliton solutions of a class of generalized nonlinear evo-lution equations are discussed analytically and numerically which is achieved using a travelling wave method to formulate one-soliton solution and the finite difference method to the numerical dolutions and the interactions between the solitons for the generalized nonlinear Schrodinger equations. The characteristic behavior of the nonlinear-ity admitted in the system has been investigated and the soliton state of the system in the limit of $\alpha\;\longrightarrow\;0$ and $\alpha\;\longrightarrow\;\infty$ has been studied. The results presented show that soliton phenomena are character-istics associated with the nonlinearities of the dynamical systems.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.3
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• pp.57-64
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• 2001

For the dynamic nonlinear analysis of stiffened plate and shell structures, total Lagrangian formulation is presented based upon the degenerated shell element considering finite rotation effects. Assumed strain concept is adopted in order to overcome shear locking phenomena and to eliminate spurious zero energy mode. In the elasto-plastic analysis, the return mapping algorithm based on the consistent elasto-plastic tangent modulus is applied to collapse analysis of shell structures. Newmark integration method is used for dynamic nonlinear analysis of shell structures under dynamic forces.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1455-1460
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• 2000

When a tube is oscillated at a resonant frequency, acoustic variables such as density, velocity, and pressure undergo very large perturbation, often described as nonlinear oscillation. In order to analyze these phenomena, nonlinear governing equation has been drived and solved numerically. Numerical simulations were accomplished to study the effect of the tube shape on the maximum pressure we can obtain. The tubes of cylindrical, conical, and cosine-shape, which have same volume and length, were investigated. Results show that the resonant frequency and patterns of pressure waves strongly depend on not only the tube shape but also the amplitude of driving acceleration. The degree of non-linearity of wave patterns was also measured by the newly defined nonlinear energy ratio of the pressure signals. It was found that the 1/2 cosine-shape tube is more suitable to induce high compression ratio than other shapes.

• Journal of Ocean Engineering and Technology
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• v.11 no.4
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• pp.1-6
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• 1997

When structures are constructed by welding, heat conduction brings welding deformation. This is accompanied by complicated mechanical phenomenon such as material nonlinear and geometric nonlinear behavior. Hitherto, the research of welding deformation has been accomplished by an analytical method and experimental data in Korea. In this paper, the computer program by F.E.M.(finite element method) which could analyze the deformation of thin plate considering phenomena(both material and geometric nonlinear behavior) has been developed and verified. The production mechanism and characteristics in the welding deformation of plate are studied by the results.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.382-385
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• 2006

A high-order spectral/boundary-element method is newly adapted as an efficient numerical tool. In this method, the velocity potential is expressed as the sum of surface potential and body potential. Then, surface potential is solved fly using the high-order spectral method and body potential is solved fly using the high-order boundary element method. Through the combination of these two methods, the wave-making problems fly a submerged sphere moving with the large amplitude oscillation are solved in time-domain. With the example calculations, nonlinear effects on free-surface profiles and hydrodynamic forces are shown and discussed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1342-1350
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• 1993

One of the undesirable nonlinear phenomena in feedback control systems is called 'wind up', which is characterized by large overshoot, slow response, and even instability. It is caused by interaction between the integrator in the controller and the saturating actuator. Limit cycle and jump resonance are another nonlinear characteristrics of systems with saturating actuators. Several 'anti-windup' compensators have been developed to prevent some of the aforementioned nonlinear characteristics such as instability and limit cycle, but none has studied the effect of anti-windup compensator on the jump resonance. In this paper, we developed an analytical method to design the compensator to prevent not only limit cycle but also jump resonance. An illustrative example is included to show the compensator eliminates jump resonance effectively.

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.624-626
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• 1997

Canonical Chua's circuit is a simple electronic circuit which exhibits a variety of bifurcation phenomena and attractors. It consists of two capacitors, an inductor, two linear resistors, and a nonlinear resistor. When the circuit exhibits chaotic signals, the nonlinear resistor of canonical Chua's circuit may have three different voltage - current characteristics. In this paper, the design methodology for practical implementation of the nonlinear resistors which have all these characteristics is described. In addition, the effectiveness of result is shown by not only the MATLAB simulation but also the PSPICE simulation.

• International Journal of Automotive Technology
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• v.7 no.1
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• pp.91-99
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• 2006

The diesel Auxiliary Power Unit (APU) for vehicle applications is a complex nonlinear system. For the purpose of this paper presents a dynamic average model of the whole system in an entirely physical way, which accounts for the non-ideal behavior of the diode rectifier, the nonlinear phenomena of generator-rectifier set in an elegant way, and also the dynamics of the dc load and diesel engine. Simulation results show the accuracy of the model. Based on the average model, a simple PI control scheme is proposed for the multivariable system, which includes the steps of model linearization, separate PI controller design with robust tuning rules, stability verification of the overall system by considering it as an uncertain one. Finally it is tested on a detailed switching model and good performances are shown for both set-point following and disturbance rejection.