• 제어로봇시스템학회논문지
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• 제4권2호
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• pp.170-177
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• 1998

In this paper, a unified solution of Hankel norm approximation problem is proposed by $\delta$-operator. To derive the main result, all-pass property is derived from the inner and co-inner property in the $\delta$-domain. The solution of all-pass becomes an optimal Hankel norm approximation problem in .delta.-domain through LLFT(Low Linear Fractional Transformation) inserting feedback term $\phi(\gamma)$, which is a free design parameter, to hold the error bound desired against the variance between the original model and the solution of Hankel norm approximation problem. The proposed solution does not only cover continuous and discrete ones depending on sampling interval but also plays a key role in robust control and model reduction problem. The verification of the proposed solution is exemplified via simulation for the zero-order Hankel norm approximation problem and the model reduction problem applied to a 16th order MIMO system.

• International Journal of Ocean System Engineering
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• 제1권1호
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• pp.28-31
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• 2011

An attempt was made to compute the free surface deformation due to the impact of a water droplet. The Cauchy Poisson, i.e. the initial value problem, was solved with the kinematic and dynamic free surface boundary conditions linearized. The zero order Hankel transformation and Laplace transform were applied to the related equations. The initial condition for the free surface profile was derived from a captured video image. The effect of the surface tension was not significant with the water mass used in this investigation. The computed and observed free surface deformations were compared.

• Structural Engineering and Mechanics
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• 제82권2호
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• pp.225-232
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• 2022

In this paper, the physical neutral surface concept is applied to study the wave propagation of functionally graded (FG) circular plate, the wave equation is derived by Hamiltonian variational principle and the first-order shear deformation plate model. Then, we convert the equations to dimensionless equations. The exact solution of wave propagation problem is obtained by Laplace integral transformation, the first order Hankel integral transformation and the zero order Hankel integral transformation. The results obtained by the current model are very close to those obtained in the existing literature, which indicates the correctness and reliability of this study. Moreover, the effects of the functionally graded index parameters and pore volume fraction on the wave propagation are also discussed in detail.

• Coupled systems mechanics
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• 제8권1호
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• pp.55-70
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• 2019

This investigation is focused on the variations in transversely isotropic thick circular plate due to time harmonic thermomechanical sources. The homogeneous thick circular plate in presence and absence of energy dissipation and two temperatures has been considered. Hankel transform is used for solving field equations. The analytical expressions of conductive temperature, displacement components, and stress components are computed in the transformed domain. The effects of frequency at different values are represented graphically. Some specific cases are also figured out from the current research.

• 한국전산구조공학회논문집
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• 제26권2호
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• pp.99-112
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• 2013

이 논문은 부분공간 시스템 확인기법을 이용하여 전단빌딩의 강성행렬과 부재의 강성을 추정하는 기법을 소개한다. 시스템 행렬은 입력-출력 데이터로 구성된 행켈행렬을 LQ 분해와 특이치 분해를 통해 추정한다. 추정된 시스템 행렬은 닮음 변환을 통해 실제 좌표축으로 변환하고, 변환된 시스템 행렬로부터 강성행렬을 계산한다. 추정된 강성행렬의 정확성과 안정성은 행켈행렬의 크기에 따라 변한다. 전단빌딩의 기저 유한요소 모델을 이용하여 행켈행렬의 크기에 따른 강성행렬의 추정 오차 곡선을 구한다. 오차 곡선을 이용하여 목표 정확도 수준에 부합하는 행켈행렬의 크기들을 결정한다. 이렇게 선택된 행렬의 크기들 중에서 부분공간 시스템 확인의 계산비용을 고려하여 보다 적절한 행렬의 크기를 결정할 수 있다. 결정된 크기의 행켈행렬을 이용하여 강성행렬을 추정하고 추정된 강성행렬로부터 부재의 강성을 추정한다. 제안된 방법을 손상 전후의 5층 전단빌딩 수치 예제에 적용하여 타당성을 검증한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.1018-1023
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• 1992

In this paper we proposed the systematic method of reducing the order of controller with robustness. State space formulae for all controllers is found by solving two coupled J-lossless coprime factorizations and model reduction problem. To reduce the order of controller, balanced truncation and Hankel approximation are used.

• 전자공학회논문지
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• 제50권4호
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• pp.26-32
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• 2013

전력선에 의한 전자유도 환경에서 가장 보편적 영향 요인이라 할 수 있는 대지의 유도전압 감쇠 효과에 대하여 분석하였다. 전력선은 원통좌표계의 라인소스로 표현되고 계의 분석은 베셀함수와 웨이브 트랜스포메이션에 의한 이의 변형 적용을 통하여 해석된다. 라인소스로부터 방사된 전자계는 지표면에서 반사되어 관측점의 피유도원 매체에 합성되는데 이것의 영향을 알기 위하여 본 논문에서는 베셀함수에 의한 지면 반사계수를 직접 구하여 산출하도록 적용하였다. 본 논문에서 설계된 통상의 유도 환경의 배치 관계에 따르면 지면반사에 의한 원천 유도원 전압과의 합성 효율은 유도전압을 감쇠시키는 차폐효과로서 60~70%정도의 범위를 나타내었다.

• 자원환경지질
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• 제18권1호
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• pp.41-47
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• 1985

Hankel변환적분의 계산에 사용되는 $J_0$ 및 $J_1$ 디지탈 선형필터의 성능을 adaptive 필터를 사용함으로써 비교 하였다. $J_0$ 영역의 어떠한 Hankel 변환적분도 수학적으로 이에 대응하는 $J_1$ 영역으로 바꿀 수 있으며, 비저항 탐사에서 이용되는 모든 전극배치에 대한 겉보기비저항은 $J_1$ 필터만으로 계산이 가능하다. 보통 $J_1$ 필터는 이와 대응하는 $J_0$필터에 비하여 정확성은 비슷하지만, 계산효율은 좀 더 높다. 또한 $J_0$에서 $J_1$영역으로 변환시키면, Schlumberger배치 뿐만 아니라 쌍극자배치 사용시에도 $J_1$함수만을 포함하는 효율적인 겉보기비저항 계산식을 이용할 수 있다.

• International Journal of Internet, Broadcasting and Communication
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• 제4권2호
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• pp.1-6
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• 2012

Control Theory for continuous-time system has been well developed. Due to the development of computer technology, digital control scheme are employed in many areas. When delays are in control systems, it is hard to control the system efficiently. Delays by controller-to-actuator and sensor-to-controller deteriorate control performance and could possibly destabilize the overall system. In this paper, a new approximated discretization method and digital design for control systems with multiple state, input and output delays and a generalized bilinear transformation method with a tunable parameter are also provided, which can re-transform the integer time-delayed discrete-time model to its continuous-time model. Illustrative examples are given to demonstrate the effectiveness of the developed method.

• Structural Engineering and Mechanics
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• 제85권5호
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• pp.645-654
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• 2023

Based on first-order shear deformation theory, a wave propagation model of graphene platelets reinforced metal foams (GPLRMFs) circular plates is built in this paper. The expressions of phase-/group- velocities and wave number are obtained by using Laplace integral transformation and Hankel integral transformation. The effects of GPLs pattern, foams distribution, GPLs weight fraction and foam coefficient on the phase and group velocity of GPLRMFs circular plates are discussed in detail. It can be inferred that GPLs distribution have great impacts on the wave propagation problems, and Porosity-I type distribution has the largest phase velocity and group velocity, followed by Porosity-III, and finally Porosity-II; With the increase of the GPLs weight fraction, the phase- and group- velocities for the GPLRMFs circular plate will be increased; With the increase of the foam coefficient, the phase- and group- velocities for the GPLRMFs circular plate will be decreased.