• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2008.04a
• /
• pp.392-395
• /
• 2008

본 논문은 퍼지 제어기를 이용하여 이산 비선형 뉴트럴 시스템을 안정화 시킨다. 시간 지연을 가지는 이산 비선형 모델에 퍼지 제어기를 연결하여 폐회로를 구성하고, 이에 대한 안정도 분석 및 성능 평가에 대해 연구한다. 이산 비선형 시스템을 먼저 T-S 퍼지모델로 모델링 하고, 모델링된 시스템을 안정화 시키기 위한 제어기를 설계한다. 퍼지 모델과 퍼지 제어기 모두 같은 멤버쉽 함수를 가진다고 가정하며, 제어기 이득값 설계를 위한 선형 행렬 부등식 조건을 유도한다. 모의 실험을 통하여 제안된 제어기의 안정도를 입증한다.

• Composites Research
• /
• v.18 no.2
• /
• pp.30-37
• /
• 2005

In this paper, geometrically non-linear finite element analyses were performed to study the mechanical behavior of the material system of the envelope of stratospheric airships. The microstructure of the load-bearing plain weave layer was identified and modeled. The Updated Lagrangian formulation was employed to consider the geometric non-linearity as well as the induced structural non-linearity for the fiber tows. The stress-strain behavior was predicted and the effective elastic modulus was calculated by numerical experiments. It was found the non-linear stress-strain curves were largely different from those by linear analysis. And non-linear elastic moduli were much higher than linear elastic moduli. The difference was more distinguishable when the tow waviness ratio was smaller.

• Computational Structural Engineering
• /
• v.11 no.4
• /
• pp.295-307
• /
• 1998

철근콘크리트 보에 대해서 인장강화효과의 소성힌지길이를 고려한 재료비선형 해석을 수행하였다. 비선형 해석에서 자유도가 많은 대형구조물에 적용시키기에는 많은 제약이 따르는 복잡한 층상해석기법을 사용하는 대신 단면해석을 통해 미리 구성된 모멘트-곡률 관계를 이용하였으며, 유한요소해석에서 사용요소의 크기에 따른 수치해석상의 오차를 줄이기 위해 인장강화효과와 소성힌지길이 개념을 도입하였다. 마지막으로 제안된 해석 알고리즘의 타당성을 검증하기 위하여 해석결과와 실험결과간의 상호 관계를 비교, 분석하였다.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.7 no.4
• /
• pp.81-90
• /
• 1997

키 수열 발생기는 함수 조합 형태에 따라 여러 가지로 분류될 수 있으며, 비도 기본 요소(랜덤 특성, 주기, 선형 복잡도, 상관 면역도, 키 수열의 수 등)는 비선형 함수에 따라 달라진다. 모든 기본 요소를 잘 만족하는 키 수열 발생기는 설계가 어렵지만, 각 요소별로 특성이 뛰어난 발생기를 잘 조합하면 고비도 시스템을 설계할 수 있다. 본 논문에서는 선형 복잡도와 상관 면역도 측면에서 강한 개선된 합산 수열 발생기와 키 수열 수사 많은 일반화된 메모리 다수열 발생기를 조합하여 혼합형 수열 발생기를 제안하고, 비도 수준을 분석하였다.

• Journal of the Institute of Convergence Signal Processing
• /
• v.2 no.1
• /
• pp.95-100
• /
• 2001

In this paper, we proposed the robust control scheme for a class of nonlinear dynamical systems using output feedback linearization method. The presented control scheme is based on the VSS. We assume that the nonlinear dynamical system is minimum phase, the relative degree of the system is r＜n and zero dynamics is stable. It is also shown that the global asymtotically stability is guaranted. And we verified that the proposed control scheme Is the feasible through a computer simulation.

• Proceedings of the Korean Statistical Society Conference
• /
• 2002.05a
• /
• pp.25-28
• /
• 2002

비선형모형분석의 초기 단계에서 초기값(starting value, initial parameter value)를 결정하는 문제는 비선형모형의 모수추정을 위한 반복기법의 수렴속도나 국소값(local minimum)문제에 영향을 주게 된다. 본 논문을 통하여 탐색적 자료분석이 초기값를 결정하는 데 도움을 줄 수 있음을 보이고자 한다.

• 한국도로학회:학술대회논문집
• /
• 2002.10a
• /
• pp.255-262
• /
• 2002

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.4
• /
• pp.669-678
• /
• 1994

This paper presents a new data predistortion technique with memory to compensate for the nonlinearities of high-power amplifiers (HPA`s) in digital radio systems employing QAM signal formats. In contrast with the conventional data predistortion technique which is designed to reduce nonlinearity of memoryless HPA`s, the proposed technique in this paper compensates not only for nonlinear warping of the signal constellation but also for clustering of the signal points caused by transmitter pulse sharping filter with memory. A practical implementation method which can reduce the size of memory at the predistortion stage is described by utilizing symmetry of QAM constellation format and Modulo-4 operation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.7C
• /
• pp.627-634
• /
• 2007

When a higher-order modulation scheme (16QAM or 64QAM) is applied to the communications system using the nonlinear high power amplifier (HPA), the performance can be degraded by the nonlinear distortion of the HPA. The nonlinear distortion can be compensated by the adaptive nonlinear Volterra equalizer using the low-complexity LMS algorithm at the receiver. However, the LMS algorithm shows very slow convergence performance. So, in this paper, the parallel M-band discrete wavelet transformed LMS algorithm is proposed in order to improve the convergence speed. Throughout the computer simulations, it is shown that the convergence performance of the proposed method is superior to that of the conventional time-domain and transform-domain LMS algorithms.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.20 no.2
• /
• pp.194-202
• /
• 2008

In general, forecast tsunami heights announced for tsunami warning are computed by using a linear tsunami model with coarse grids which leads the underestimation of inundation area. Thus, an accurate tsunami inundation map corresponding the forecast tsunami height is needed for an emergency evacuation plan. A practical way to construct a relatively accurate tsunami inundation map was proposed in this study for the quantitative forecast of inundation area. This procedure can be introduced as in the followings: The fault dislocations of potential tsunami sources generating a specific tsunami height near an interested area are found by using a linear tsunami model. Based on these fault dislocations, maximum inundation envelops of the interested area are computed and illustrated by using nonlinear inundation numerical model. In this study, the tsunami inundation map for Imwon area was constructed according to 11 potential tsunami sources, and the validity of this process was examined.