• 한국콘텐츠학회논문지
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• 제2권2호
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• pp.27-35
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• 2002

본 연구는 얼굴 성형을 시뮬레이션하거나 성형 상담 자료로 활용할 목적으로 한 쌍의 제어점을 이용한 쌍선형 워핑 및 쌍선형 보간에 의한 성형 시스템에 관한 것이다. 우선, 주어진 영상을 대상으로 제어점을 설정하고, 이 제어점을 이용하여 워핑 영역을 결정한다. 그리고, 이 워핑 영역은 제어 점을 한 꼭지점으로 하는 4개의 부분 영역으로 나눈다. 그런 후, 4개의 부분 영역 각각에 대한 역방향 사상의 워핑 계수를 구한다. 결과 영상의 부분 영역에 있는 모든 화소 위치에 대하여 대응하는 워핑 계수를 적용하여 원 영상에서 대응되는 화소 위치를 구한다. 이 위치에 최인접하는 네 화소값을 이용하여 쌍선형 보간에 의해 결과 영상의 화소에 대한 화소값을 구한다. 이와 같은 방식으로 4개의 부분 영역에 대하여 동일하게 처리함으로써 성형 효과를 얻게 된다. 실험 결과, 워핑 영역의 경계에서 끊김이 없는 자연스런 성형 효과를 얻을 수 있었다.

• Structural Engineering and Mechanics
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• 제39권4호
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• pp.465-498
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• 2011

Concrete structures are generally cracked in flexural tension at working loads. Concrete beams with asymmetric section details and crack patterns exhibit different flexural rigidity depending upon the sense of the applied flexural moment. In this paper, three different models, having the same natural period, of such SDOF bilinear dynamical systems have been proposed. The Model-I and Model-II have constant damping coefficient, but the latter is characterized by two stiffness coefficients depending upon the sense of vibration amplitude. The Model-III, additionally, has two damping coefficients as well. In this paper, the dynamical response of Model-III to sinusoidal loading has been investigated and compared with that of Model-II studied earlier. It has been found that Model-III exhibits regular and irregular sub-harmonics, jump phenomena and strong sensitivity to initial conditions, forcing frequency, system period as well as the sense of peak sinusoidal force. The constant sustained load has been found to affect the natural period of the dynamical system. The predictions of Model-I have been compared with those of the approximate linear model adopted in present practice. The behaviour exhibited by different models of the SDOF cracked elastic concrete structures under working loads and the theoretical and practical implications of the approach followed have been critically evaluated.

• Earthquakes and Structures
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• 제7권6호
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• pp.1223-1240
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• 2014

Seismic isolation has been established as an effective earthquake-resistant design method and the lead rubber bearings (LRBs) are among the most commonly used seismic isolation systems. In the scientific literature, a sharp bilinear model is often used for capturing the hysteretic behaviour of the LRBs in the analysis of seismically isolated structures, although the actual behaviour of the LRBs can be more accurately represented utilizing smoothed plasticity, as captured by the Bouc-Wen model. Discrepancies between these two models are quantified in terms of the computed peak relative displacements at the isolation level, as well as the peak inter-storey deflections and the absolute top-floor accelerations, for the case of base-isolated buildings modelled as multi degree-of-freedom systems. Numerical simulations under pulse-like ground motions have been performed to assess the effect of non-linear parameters of the seismic isolation system and characteristics of both the superstructure and the earthquake excitation, on the accuracy of the computed peak structural responses. Through parametric analyses, this paper assesses potential inaccuracies of the computed peak seismic response when the sharp bilinear model is employed for modelling the LRBs instead of the more accurate and smoother Bouc-Wen model.

• 청정기술
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• 제8권1호
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• pp.27-37
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• 2002

본 연구에서는 오존 예측 시스템의 개발에 있어서 쌍일차 모델의 성능 및 효용성을 확인하기 위하여 쌍일차 모델 및 선형 모델을 이용한 오존 형성의 모델인식 모사실험을 하였으며 또한 쌍일차 모델을 이용한 오존 형성의 예측결과를 서울시의 측정자료 및 선형모델의 예측결과와 비교하였다. 모델인식에 있어서는 ARMA 모델을 사용하였으며 모델의 파라미터를 평가하기 위하여 방정식 오차법에 근거한 연속 파라미터 평가 알고리즘을 적용하였다. 모델인식 실험결과로부터 쌍일차 모델을 이용한 오존 형성량과 모사기로부터 얻은 오존 형성량이 거의 일치함을 알 수 있었으며 또한 예측결과와 서울시 측정자료와의 비교로부터 오존예보시스템을 위한 실시간 및 단시간 오존 형성량의 예측방법 개발에 있어서 본 연구에서 제안한 방법의 타당성을 확인할 수 있었다.

• 대한전기학회논문지
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• 제40권3호
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• pp.290-298
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• 1991

In the paper, the bilinear transformation method is applied to the design of servo system adopting the use of the internal model principle and the pole assignment method in a specified region. The pole assignment problem for the augmented system has been solved by using Tustin's function. The properties of Tustin's function have been shown in relation to the s-plane and z-planes, and the feedback law relationship between the original system and the transformed system has been cleared. The effectiveness of the proposed approach is proved via application for the cart system and the designed cart system is implemented by digital control with microcomputer and A-D/D-A converter.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.386-391
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• 2003

This paper focuses on robust $H_{\infty}$ control for bilinear systems with time-varying parameter uncertainties and exogenous disturbance via output feedback. $H_{\infty}$ control is achieved via separation into a $H_{\infty}$ state feedback control problem and a $H_{\infty}$ state estimation problem. The suitable robust stabilizing output feedback control law can be constructed in term of approximated solution to x-dependent Riccati equation using successive approximation technique. Also, the $H_{\infty}$ filter gain can be constructed in term of solution to algebraic Riccati equation. The output feedback control robustly stabilizes the plant and guarantees a robust $H_{\infty}$ performance for the closed-loop systems in the face of parameter uncertainties and exogenous disturbance.

• Earthquakes and Structures
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• 제8권5호
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• pp.1055-1067
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• 2015

A theoretical procedure to estimate spectral displacement of a hysteretic oscillator with bilinear stiffness excited by band-limited excitation is presented. The stochastic method of ground-motion simulation is combined with the random vibration theory to compute linear and nonlinear structural response. The response is obtained by computing the root-mean-square oscillator response using dissipation energy balancing by integrating over all energy levels of system weighting with the stationary probability density of the energy. The results are presented in a convenient form, and the accuracy of the procedure is assessed by comparison with results obtained with the time-domain method using the recorded data. The model shows little or no bias at the structural period of engineering interest.

• 제어로봇시스템학회논문지
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• 제19권9호
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• pp.827-833
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• 2013

In this paper, an efficient computational method is presented for state space analysis of bilinear systems via Legendre wavelets. The differential matrix equation is converted to a generalized Sylvester matrix equation by using Legendre wavelets as a basis. First, an explicit expression for the inverse of the integral operational matrix of the Legendre wavelets is presented. Then using it, we propose a preorder traversal algorithm to solve the generalized Sylvester matrix equation, which greatly reduces the computation time. Finally the efficiency of the proposed method is discussed using numerical examples.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권12호
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• pp.5553-5571
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• 2016

In this paper, we introduce a new concept called generalized ring signcryption (GRSC), which can achieve ring signature and ring signcryption functions with only one key pair and one algorithm. It is very useful for a system which has a large number of users, or has limited storage space, or whose function requirements may be changed later. We give a formal definition and a security model of GRSC and propose a concrete scheme based on bilinear pairings. In the random oracle model, the scheme's confidentiality can be proved under the GBDH assumption, and its unforgeability can be proved under GDH' assumption, and what is more, this scheme also allows unconditional anonymity. Compared with other identity-based ring signcryption schemes that use bilinear pairings as well, our scheme is a highly efficient one.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2037-2039
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• 2002

This paper focuses on robust $H_{\infty}$ control for bilinear systems with time-varying parameter uncertainties via state feedback. The suitable robustly stabilizing feedback control law can be constructed in term of solution to a state variable x-dependent quadratic Riccati equation using successive approximation technique. Also, the state feedback control law robustly stabilizes the plant and guarantees a robust $H_{\infty}$ performance for the closed-loop bilinear system with parameter uncertainties and exogenous disturbance.