• Journal of the Korean Society of Safety
• /
• v.14 no.4
• /
• pp.148-157
• /
• 1999

Dynamic structural behavior in long span bridges, especially cable structures, is very sophisticated due to their flexibility and structural members are sequentially erected in each construction step. In this study, the consistent mass matrix for dynamic analysis is formulated and computational program considering construction sequences is developed where structural members can be builded or removed by command language and automatically reanalyzed in the moment when structural system is changed. The dynamic analysis, i.e. eigenvalue and time series analysis and the geometrically nonlinear analysis considering construction sequence are conducted to the Namhae Bridge. The analytical results are satisfactory compared with measuring values and the developed computational program can successfully be applied to design and safety check.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.11 no.1
• /
• pp.87-92
• /
• 2016

Van der Pol's oscillators is non-conservative oscillator that having nonlinear damping phenomena. The energy of its system is dissipative at a high amplitude whereas its system creates the energy at low amplitude. In order to identify another behaviors in the Van der Pol oscillator, the periodic external force applied in the Van der Pol oscillator. This paper confirms the pattern of variation for the limit cycle according to parameter variation in order to identify another behaviors in the Van der Pol oscillator.

• International Journal of Control, Automation, and Systems
• /
• v.6 no.4
• /
• pp.495-505
• /
• 2008

This paper describes modeling Voltage Sourced Inverter (VSI) type Flexible AC Transmission System (FACTS) controllers and control methods for power system dynamic stability studies. The considered FACTS controllers are the Static Compensator (STATCOM), the Static Synchronous Series Compensator (SSSC), and the Unified Power Flow Controller (UPFC). In this paper, these FACTS controllers are derived in the current injection model, and it is applied to the linear and nonlinear analysis algorithm for power system dynamics studies. The parameters of the FACTS controllers are set to damp the inter-area oscillations, and the supplementary damping controllers and its control schemes are proposed to increase damping abilities of the FACTS controllers. For these works, the linear analysis for each FACTS controller with or without damping controller is executed, and the dynamic characteristics of each FACTS controller are analyzed. The results are verified by the nonlinear analysis using the time-domain simulation.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05a
• /
• pp.79-86
• /
• 1998

The nonlinear analytic function expansion nodal (AFEN) method is applied to the solution of the time-dependent neutron diffusion equation. Since the AFEN method requires both the particular solution and the homogeneous solution to the transient fixed source problem, the derivation solution method is focused on finding the particular solution efficiently. To avoid complicated particular solutions, the source distribution is approximated by quadratic polynomials and the transient source is constructed such that the error due to the quadratic approximation is minimized. In addition, this paper presents a new two-node solution scheme that is derived by imposing the constraint of current continuity at the interface corner points. The method is verified through a series of applications to the NEACRP PWR rod ejection benchmark problem.

• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.2624-2626
• /
• 2000

The stabilization controls of coupled tank system and ball-beam system are difficult control tasks because of their high order time delay, nonlinearity and structural unstability. Fuhermore, a series of classical methods such as a conventional PID and a full state feedback controller(FSFC) based on the local linearizations have narrow stabilizable regions. Therefore, in this paper, in order to stabilize two representative nonlinear system mentioned above, a Sliding Mode Controller based on a Real Variable Elitist Genetic Algorithm(RVEGA SMC) was proposed.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2010.05a
• /
• pp.1620-1624
• /
• 2010

The NLCCA has been applied to analyze the East Asia sea surface temperature (SST) and Korea monthly precipitation, where the eight leading PCs of the SST and the eight PCs of the precipitation during 1973-2007 were inputs to an NLCCA model. The first NLCCA mode is plotted in the PC spaces of the Korea precipitation and the world SST present a curve linking the nonlinear relationship between the first three leading PCs of Korea precipitation and world SST forthright. The correlation coefficient between canonical variate time series u and v is 0.8538 for the first NLCCA mode. And there are some areas' climate variability have higher relationship with Korea precipitation, especially focus on the north of East Sea' climate variability have represented the higher canonical correlation with Korea precipitation, with the correlation coefficient is 0.871 and 0.838. Likewise in Korea, most stations display similarly uniform distributing characteristic and less difference, in particular the inshore stations have display identical distributing characteristic. In correlation variables' scores, the fluctuation and variation trend are also seasonal oscillation with high frequency.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.8 no.11
• /
• pp.1691-1696
• /
• 2013

In this paper, an analysis of behavior is performed in the circular hybrid energy harvesting device. This analysis of behavior is to confirm with or without an existence of nonlinear system because its system is required to produce the more energy. To do this, first of all the phase portrait is reconstructed through Taken's embedding method, and then Poincare map is organized by using phase portrait and finally Lyapunov exponent is analyzed.

• Proceedings of the KIEE Conference
• /
• 1999.07g
• /
• pp.2911-2913
• /
• 1999

This paper suggest an optimal identification method to complex and nonlinear system modeling that is based on Fuzzy-Neural Network(FNN). The FNN modeling implements parameter identification using HCM algorithm and optimal identification algorithm structure combined with two types of optimization theories for nonlinear systems, we use a HCM Clustering Algorithm to find initial parameters of membership function. The parameters such as parameters of membership functions, learning rates and momentum coefficients are adjusted using optimal identification algorithm. The proposed optimal identification algorithm is carried out using both a genetic algorithm and the improved complex method. Also, an aggregate objective function(performance index) with weighted value is proposed to achieve a sound balance between approximation and generalization abilities of the model. To evaluate the performance of the proposed model, we use the time series data for gas furnace, the data of sewage treatment process and traffic route choice process.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1996.10a
• /
• pp.6-10
• /
• 1996

This paper presents an overview of research results obtained by the authors in a series of publications. Methods are developed both for time-varying and time-invariant for linear and nonlinear. for time domain and frequency domain . and for discrete-time and continuous-time systems. Among the topics presented are: 1. Learning control based on integral control concepts applied in the repetition domain. 2. New algorithms that give improved transient response of the indirect adaptive control ideas. 4. Direct model reference learning control. 5 . Learning control based frequency domain. 6. Use of neural networks in learning control. 7. Decentralized learning controllers. These learning algorithms apply to robot control. The decentralized learning control laws are important in such applications becaused of the usual robot decentralized controller structured.

• Proceedings of the KIEE Conference
• /
• 1999.07c
• /
• pp.1029-1031
• /
• 1999

This paper presents an $H_{\infty}$ based robust STATCOM supplementary controller design to suppress the SSR in series-compensated line. This controller is designed to have the robust stability against the plant model uncertainty. Time domain simulations using a nonlinear system model show that the proposed STATCOM supplementary controller can suppress the SSR efficiently against the plant model uncertainty