• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1135-1137
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• 2005

단위 무게당 추력특성이 다른 전동기에 비해 우수한 것으로 나타나 있는 횡축형 선형전동기에 대한 연구가 많이 진행되고 있다. 본 논문에서는 횡축형 선형 전동기의 동적 시뮬레이션을 수행할 수 있는 시뮬레이션 모델을 개발하였다. 전동기의 설계단계에서는 주로 정적인 특성만을 고려하여 설계가 진행되지만, 이렇게 설계된 전동기는 실제 실험 결과와 설계 명세간의 차이가 많이 발생하는 경우가 있다. 본 논문에서 개발된 동적 시뮬레이션 모델을 이용한 결과를 설계 단계에서 적용한다면 좀 더 실제적인 전동기 설계를 할 수 있을것으로 기대된다. 또한 제작된 전동기의 성능 평가를 하는 경우 성능의 기준으로 활용할 수 있을 것으로 생각된다.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.4
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• pp.257-263
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• 1996

본 논문에서는 기계적 위치 제어계에서 다단계 뱅-뱅 액츄에이터의 비선형성에 의한 목표 위치에서의 리미트 사이클을 방지하는 제어방법을 제안한다. 다단계 뱅-뱅 액츄에이터의 선형화된 모델인 기술함수를 이용하여 비선형성을 보상한다. 강인성을 확보하기 위해 루프 형성 기법에 의한 H/sub .inf./ 제어기가 설계된다. 제안된 제어방법은 기존의 선형제어기보다 비선형성이 보상되어 사역대가 작아지므로 최소 제어 가능 구간을 줄일 수 있다. 1축 위치 제어계의 실험을 하여 제안된 제어방법이 리미트 사이클을 줄이고 제어정도를 향상 시키는데 유효함을 입증하였다.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.511-517
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• 2010

The purpose of this study is to investigate the shear behavior of prestressed concrete deep beams and to provide the data for development of improved design criteria. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated nonlinear finite element analysis program. Hence, in this study, the computer program, named RCAHEST (reinforced concrete analysis in higher evaluation system technology), was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. A bonded or unbonded tendon element based on the finite element method, that can represent the interaction between tendon and concrete of prestressed concrete member, is used. The proposed numerical method for the shear behavior of prestressed concrete deep beams is verified by comparing the analytical results with test data by others.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.5
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• pp.537-543
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• 2006

There have been many recent studies on the nonlinear rainfall-runoff modeling, where the use of neural networks is shown to be quite successful. Due to fundamental limitation of linear structures, employing linear models has often been considered inferior to the neural network approaches in this area. However, we believe that with an appropriate extension, the concept of linear impulse responses can be a viable tool since it enables us to understand underlying dynamics principles better. In this paper, we propose the use of multiple impulse responses for the problem of rainfall-runoff analysis. The proposed method is based on a simple and fixed strategy for switching among multiple linear impulse-response models, each of which satisfies the constraints of non-negativity and uni-modality. The computational analysis performed for a certain Korean hydrometeorologic data set showed that the proposed method can yield very meaningful results.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.641-648
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• 1997

Mutual information is useful for analyzing nonlinear dependence in time series in much the same way as correlation is used to characterize linear dependence. We use multivariate kernel density estimators for the estimation of mutual information at different time lags for single and multiple time series. This approach is tested on a variety of hydrologic data sets, and suggested an appropriate delay time $ au$ at which the mutual information is almost zerothen multi-dimensional phase portraits could be constructed from measurements of a single scalar time series.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.6
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• pp.45-56
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• 1999

This paper presents a method for designing an autopilot of the BTT missile using 2DOF Wiener-Hopf control technique to improve tracking performance. Linear controllers are designed based on the linearized models which are obtained from the nonlinear missile dynamic equations at various operating points. The gain scheduling technique is used to implement the final autopilot. A simulation on the flight of missiles is carried out through the use of 6DOF equation program including exact nonlinear equations of the missile and the variations of aerodynamic variables in order to check applicability of the suggested method in real situation.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1781-1782
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• 2008

본 논문은 시간 지연을 가지는 이산 시간 비선형 상호 결합 시스템의 분산 퍼지 출력 궤환 제어기의 설계에 대해 연구한다. T-S(Takagi-Sugeno) 퍼지 모델 기법을 이용하여 퍼지 상호 결합 시스템을 구한다. 이를 바탕으로 분산 퍼지 출력 궤환 제어기를 설계하고, 폐루프 시스템의 안정도 충분 조건을 선형 행렬 부등식 (LMI)의 형태로 나타낸다. 설계된 이득값을 통하여 상호 결합 시스템이 안정화됨을 모의실험을 통하여 보인다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.6
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• pp.651-659
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• 2011

With the increase in the thermal power output of recently developed nuclear power plants, the applied forces and moments are increased in some piping systems, so that the leak-before-break (LBB) application criteria would not be satisfied in those pipes. In this paper, we present a method for obtaining the additive LBB margin in the pipes by considering the nonlinearity of the crack and material properties. Finite element analysis and the moment-rotation equation of beam theory were used to calculate the nonlinearity of the crack and material properties. Moreover crack stability analysis was performed using the method proposed in this study. The LBB margin was increased effectively through consideration of the nonlinearity of the crack and material properties in the pipe.

• Korean Journal of Optics and Photonics
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• v.6 no.2
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• pp.135-141
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• 1995

Phenomenological nonlinear gain saturation effect on the noise characteristics of a multi-electrode DBR laser, when the lasing wavelength changes continuously, is presented theoretically. Using the optical transmission line theory, noise characteristics reliant on output power are analyzed by taking into account both the spontaneous enhancement factor K due to the distribution of the spontaneous emission along the active cavity and the nonlinear gain saturation effect. Spontaneous emission rate was increased due to an increase in injected current into the passive section, which in turn lead to increase in relative intensity noise (RIN) and frequency noise. Phenomenological nonlinear gain saturation was found to have significant effect on RIN and frequency noise characteristics. However. Iinewidth was found to decrease due to a phenomenological nonlinear gain saturation effect. ffect.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.12
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• pp.24-30
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• 2010

The super-resolution near-field structure (super-RENS) disc system is the most promising one for next-generation optical data storage systems to succeed the Blu-ray disc (BD). In this paper, we apply the simplicial canonical piecewise-linear (SCPWL) model to modeling super-RENS read-out signals since reliable and accurate channel modeling is essential for performance analysis and development of equalizers for super-RENS systems. The validity of this model is verified using radio frequency (RF) signal samples obtained from a super-RENS disc, The experiment results on modeling indicate that the SCPWL model can be efficiently utilized for the nonlinear modeling of the super-RENS systems.