• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.777-780
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• 1991

The practical implementation of model reference adaptive systems(MRAS) using digital computer requires the derivation of discrete-time adaptation laws. This is specially important in the case of direct driver robot and light weight manipulator where inertia changes ang gravity effects are significant. We develope a discrete-time model reference adaptive control scheme for trajectory tracking of robot manipulator. Instead of the conventional Lyapunov approach hyperstabillty theory is more appealing than the Lyapunov approach. It is better suited to discrete time systems and offers more flexibility in design by providing additional free design parameters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.69-72
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• 1987

General schemes for the adaptive control and identification of multivariable systems by model reference approach are developed. Lyapunov's direct method and LaSalle's theorem are employed to ensure the stability of these schemes. An added feature is the simplicity of the stable adaptive laws, which depend explicitly on the state variables of plant and model, and on the plant input. Computer simulation results of several examples illustrate the the effectiveness of the proposed schemes.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권1호
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• pp.31-37
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• 2001

A robust adaptive technique for the longitudinal control of a platoon of automated vehicles is presented. A nonlinear model is used to represent the dynamics of each vehicle within the platoon. The external disturbances such as wind gust and a disturbance term due to engine transmission variations and so on are considered. The state observer is used to avoid direct measurement of the relative velocity or acceleration between the controlled and leading vehicles or the controlled vehicles's acceleration. The proposed controller guarantees to recover platoon stability in operation even if a speed dependent spacing policy is adopted, which incorporates a constant time headway in addition to the constant distance. It is shown that the proposed observer is exponentially stable, and the at the robust adaptive controller is stable. The simulation results demonstrate excellent tracking even in the presence of disturbances.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1996년도 창립기념 전력전자학술발표회 논문집
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• pp.13-16
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• 1996

A new instantaneous torque control technique is presented for a high performance control of a permanent magnet synchronous motor. Using the model reference adaptive system technique, the linkage flux of the motor is estimated and the torque is instantaneously controlled by the proposed torque controller combining with a variable structure control and space vector PWM. The proposed torque control provides the advantage of reducing the torque pulsation caused by the flux harmonics. This control strategy is applied to the high torque PM synchronous motor drives for direct drive systems and is implemented by using a software of the DSP TMS320C30. The experiments are carried out for this system and the results well demonstrate the effectiveness of the proposed control.

• 한국심리학회지 : 문화 및 사회문제
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• 제28권3호
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• pp.331-352
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• 2022

본 연구는 청소년의 게임이용시간과 자기통제의 시간에 따른 변화와 적응적 게임활용이 지니는 종단적 매개효과를 검증하기 위하여 잠재성장모형을 활용하였다. 적응적 게임활용의 종단매개효과 검증을 위하여 한국콘텐츠진흥원에서 주최한 2019 게임이용자패널연구 학술대회 참여를 통해 제공받은 청소년 863명의 게임이용자패널조사 4개년 응답자료를 활용하였다. 본 연구모형을 분석하기 위하여 SPSS 21.0과 Mplus 6.12를 활용하여, 각 변인의 시점별 정규성을 확인 후 상관분석, 종단적 매개분석을 순차적으로 실시하였다. 연구결과를 요약하면 다음과 같다. 첫째, 잠재성장모형을 분석한 결과, 게임이용시간과 적응적 게임활용, 자기통제는 모두 시간에 따라 선형적으로 성장하였다. 둘째, 측정된 변인들의 초기치와 변화율 간 관계를 분석한 결과 게임이용시간이 자기통제에 미치는 직접적인 영향은 유의하지 않았으나 적응적 게임활용을 통해 자기통제에 정적으로 유의한 영향을 미치는 것으로 나타났다. 지속적인 적응적 게임활용은 자기통제수준을 높이는 것으로 확인되었다. 셋째, Sobel 검증 결과, 적응적 게임활용의 초기치와 변화율 모두 완전 매개효과를 갖는 것으로 나타나 종단매개효과가 유의함을 확인하였다. 본 연구는 청소년의 자기통제 수준이 게임이용시간과 적응적 게임활용의 변화양상에 따라 변화를 보이는 종단적 과정을 통해 적응적 게임활용의 중요성을 확인하였다.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.139-148
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• 2006

Catmull-Clark subdivision scheme provides a powerful method for building smooth and complex surfaces. But the number of faces in the uniformly refined meshes increases exponentially with respect to subdivision depth. Adaptive tessellation reduces the number of faces needed to yield a smooth approximation to the limit surface and, consequently, makes the rendering process more efficient. In this paper, we present a new adaptive tessellation method for general Catmull-Clark subdivision surfaces. Different from previous control mesh refinement based approaches, which generate approximate meshes that usually do not interpolate the limit surface, the new method is based on direct evaluation of the limit surface to generate an inscribed polyhedron of the limit surface. With explicit evaluation of general Catmull-Clark subdivision surfaces becoming available, the new adaptive tessellation method can precisely measure error for every point of the limit surface. Hence, it has complete control of the accuracy of the tessellation result. Cracks are avoided by using a recursive color marking process to ensure that adjacent patches or subpatches use the same limit surface points in the construction of the shared boundary. The new method performs limit surface evaluation only at points that are needed for the final rendering process. Therefore it is very fast and memory efficient. The new method is presented for the general Catmull-Clark subdivision scheme. But it can be used for any subdivision scheme that has an explicit evaluation method for its limit surface.

• Structural Engineering and Mechanics
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• 제65권6호
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• pp.721-730
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• 2018

This paper aims to inspect the effectiveness of the Simple Adaptive Control Method (SACM) to control the response of asymmetric buildings with rotationally non-linear behavior under seismic loads. SACM is a direct control method and was previously used to improve the performance of linear and non-linear structures. In most of these studies, the modeled structures were two-dimensional shear buildings. In reality, the building plans might be asymmetric, which cause the buildings to experience torsional motions under earthquake excitation. In this study, SACM is used to improve the performance of asymmetric buildings, and unlike conventional linear models, the non-linear inertial coupling terms are considered in the equations of motion. SACM performance is compared with the Linear Quadratic Regulator (LQR) algorithm. Moreover, the LQR algorithm is modified, so that it is appropriate for rotationally non-linear buildings. Active tuned mass dampers are used to improve the performance of the modeled buildings. The results show that SACM is successful in reducing the response of asymmetric buildings with rotationally non-linear behavior under earthquake excitation. Furthermore, the results of the SACM were very close to those of the LQR algorithm.

• 한국항공우주학회지
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• 제33권3호
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• pp.39-46
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• 2005

본 논문에서는 광범위한 함수 근사성질을 갖고 있는 신경회로망을 이용하여, 시스템의 입출력 조화성분의 선형관계를 표현하기 위해 추정된 전달행렬의 적용범위를 확장할 수 있는 적응 고차조화제어(Higher Harmonic Control, HHC) 기법을 제안하고 있다. 신경회로망의 학습신호는 추정된 전달행렬을 기반으로 계산된 최적제어 이득 값 행렬을 이용하여 구성된다. 내부 안정성을 보장하기 위하여 신경회로망의 가중치 학습방법은 Lyapunov 직접 방법을 이용하여 유도하였다. 6개의 입력과 2개의 출력을 갖는 비선형 시스템에 대한 시뮬레이션 결과를 통해 적응 고차조화제어 기법이 불확실한 전달행렬에 적용 가능함을 보였다.

• 전자공학회논문지SC
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• 제41권4호
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• pp.21-28
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• 2004

본 논문에서는 다변수 비선형 시스템에 적응할 수 있는 신경회로망을 이용한 직접 다변수 자기동조 제어기를 제안한다. 제어기에 적용되는 플랜트는 고차이고 잡음, 시간지연과 상호결합 항이 존재하며 파라미터가 변하는 다변수 비선형 비최소위상 시스템이다. 비선형성은 전체적인 유계라 가정하며, 시스템은 선형부분과 비선형부분으로 분리한 형태로 구성한다. 다변수 비선형 자기동조 제어기의 제어 출력은 신경회로망으로 직접 추정된 제어기 파라미터로부터 얻어진다. 제어 알고리듬의 타당성을 확인하기 위해 시간지연이 있고 일정한 시간이 경과한 후 시스템의 파라미터가 변하는 고차 다변수 비선형 비최소위상 시스템에 대해 컴퓨터 시뮬레이션을 하였다. 그리고 신경회로망을 이용한 직접 다변수 적응 제어기와 비교하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.2992-2994
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• 1999

This paper investigates the direct adaptive control of nonlinear systems using RBFN(radial basis function networks). The structure of the controller consists of a fixed PD controller and a RBFN controller in parallel. An adaptation law for the weight adjustment is developed based on the Lyapunov stability theory to guarantee the stability of the overall control scheme. Also, the tracking errors between the system outputs and the desired outputs converge to zero asymptotically. To evaluate the performance of the controller, the proposed method is applied to the trajectory control of the two-link manipulator.