• 대한전기학회논문지
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• 제39권1호
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• pp.36-48
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• 1990

브러쉬없는 직류전동기의 위치제어시 새로운 제어방법을 제시하였다. 일반적으로 브러쉬없는 직류전동기의 모델식은 비선형특성을 갖는다. 이 비선형특성을 벡터제어에 근거한 filed orientation방법으로 선형화시켰고, 선형화된 시스템에 새로운 상태변수를 첨가한 상태변수 궤환(augmented state variable feedback)방법이 적용될 수 있음을 보였다. 또한 부하외란을 미지의 입력으로 본 0-관측기(0-observer)로 부터 관측하고 여기서 얻은값을 이용하여 응답이 빠른 feedforward로 보상하였다. 이로써 전체시스템의 응답특성을 변화시키지 않고도 외란에 안정한(robust)특성이 얻어짐을 보였다. 전체 시스템은 마이크로 프로세어 MC68000을 이용한 디지탈 제어기로 구현하였고, 각 제어 알고리즘에 대한 시뮬레이션 및 실험결과로 제안된 제어알고리즘의 효과를 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.492-492
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• 2000

This paper proposes LQ optimal controller design method based on the modal decomposition. Here, the design problem of linear time-invariant systems is considered by using pencil model. The mathematical model based on matrix pencil is one of the most general representation of the system. By adding some conditions the model can be reduced to traditional system models. In pencil model, the state feedback is considered as an algebraic constraint between the state variable and the control input variable. The algebraic constraint on pencil model is called purely static mode, and is included in infinite mode. Therefore, the information of the constant gain controller is included in the purely static mode of the augmented system which consists of the plant and the control conditions. We pay attention to the coordinate transformation matrix, and LQ optimal controller is derived from the algebraic constraint of the internal variable. The proposed method is applied to the numerical examples, and the results are verified.

• 오토저널
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• 제15권1호
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• pp.81-88
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• 1993

A direct treatment of the min-max type objective function of the dynamic response optimization problem is proposed. Previously, the min-max type objective function was transformed to an artificial design variable and an additional point-wise state variable constraint function was imposed, which increased the complexity of the optimization problem. Especially, the design sensitivity analysis for the augmented Lagrangian functional with the suggested treatment is established by using the adjoint variable method and a computer program to implement the proposed algorithm is developed. The optimization result of the proposed treatment are obtained for three typical problems and compared with those of the previous treatment. It is concluded that the suggested treatment in much more efficient in the computational effort than the previous treatment with giving the similar optimal solutions.

• International Journal of Control, Automation, and Systems
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• 제4권1호
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• pp.1-9
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• 2006

This paper presents the modeling and multivariable feedback control of a novel high-precision multi-dimensional positioning stage. This integrated 6-degree-of-freedom. (DOF) motion stage is levitated by three aerostatic bearings and actuated by 3 three-phase synchronous permanent-magnet planar motors (SPMPMs). It can generate all 6-DOF motions with only a single moving part. With the DQ decomposition theory, this positioning stage is modeled as a multi-input multi-output (MIMO) electromechanical system with six inputs (currents) and six outputs (displacements). To achieve high-precision positioning capability, discrete-time integrator-augmented linear-quadratic-regulator (LQR) and reduced-order linearquadratic-Gaussian (LQG) control methodologies are applied. Digital multivariable controllers are designed and implemented on the positioning system, and experimental results are also presented in this paper to demonstrate the stage's dynamic performance.

• Smart Structures and Systems
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• 제24권3호
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• pp.361-377
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• 2019

The stiffness of shape memory alloy (SMA) spring while in actuation is represented by an empirical model that is derived from the logistic differential equation. This model correlates the stiffness to the alloy temperature and the functionality of SMA spring as active variable stiffness actuator (VSA) is analyzed based on factors that are the input conditions (activation current, duty cycle and excitation frequency) and operating conditions (pre-stress and mechanical connection). The model parameters are estimated by adopting the nonlinear least square method, henceforth, the model is validated experimentally. The average correlation factor of 0.95 between the model response and experimental results validates the proposed model. In furtherance, the justification is augmented from the comparison with existing stiffness models (logistic curve model and polynomial model). The important distinction from several observations regarding the comparison of the model prediction with the experimental states that it is more superior, flexible and adaptable than the existing. The nature of stiffness variation in the SMA spring is assessed also from the Dynamic Mechanical Thermal Analysis (DMTA), which as well proves the proposal. This model advances the ability to use SMA integrated mechanism for enhanced variable stiffness actuation. The investigation proves that the stiffness of SMA spring may be altered under controlled conditions.

• Journal of information and communication convergence engineering
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• 제2권3호
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• pp.198-201
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• 2004

In this paper, the discrete optimal control is made to have the robust property of Sliding mode controller. A augmented system with a virtual state is constructed for this objective and noble sliding surface is constructed based on this system. The sliding surface is the same as the optimal control trajectory in the original system. The states follow the optimal trajectory even if there exist uncertainties. The reaching phase problem of sliding mode control is disappear in this method.

• 대한화학회지
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• 제68권2호
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• pp.93-106
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• 2024

이 연구에서는 증강현실을 활용한 소집단 학습에서 도구 공유 정도에 따른 학생들의 현존감, 몰입, 상황흥미의 차이를 조사하였다. 중학교 2학년 학생 84명이 각각 4명씩 소집단을 구성하여 연구에 참여하였다. 각 소집단을 마커와 스마트폰의 공유 여부에 따라 공유 환경(마커와 스마트폰 공유 사용), 혼합 환경(마커 공유 및 스마트폰 개별 사용), 개별 환경(마커와 스마트폰 개별 사용)으로 무선 배치하였다. '물질의 특성' 단원에서 증강현실을 활용한 소집단 학습을 3차시 동안 실시하였다. 종속 변인에 대한 일원 분산 분석 결과, 공유 환경 대비 혼합 환경에서는 현존감과 상황흥미가, 개별 환경에서는 몰입과 상황흥미가 각각 통계적으로 유의하게 더 높았다. 각 종속 변인의 하위요소에 대한 다변량 분산 분석 결과, 현존감에서는 실제성, 몰입에서는 선행요소와 경험요소, 상황흥미에서는 순간적 즐거움, 새로움, 전체 흥미에서 각각 통계적으로 유의한 차이가 있었다. 면담 및 수업 관찰 결과, 공유 환경과 개별 환경의 학생들은 증강현실을 활용할 때 개별적으로 스마트폰을 사용하는 경향이 있었지만 혼합 환경의 학생들은 스마트폰을 협력적으로 사용하며 더 활발하게 상호작용하는 경향이 나타났다. 연구 결과를 바탕으로 도구 사용 환경의 측면에서 증강현실을 활용한 소집단 학습의 효과를 높이기 위한 방안을 제안하였다.

• Communications for Statistical Applications and Methods
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• 제11권2호
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• pp.345-353
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• 2004

Graphical methods for the specification of the curvature as a function of two predictors are animated to see the effect of an added variable to the model. Through a 3D animated plot it might be difficult to find a sequence of interpretable plots. But examples demonstrate that useful information can be obtained by using rotation technique in 3D plot. Besides 3D plots, an example of 2D animated plot applied to the case of high correlation between predictors and an added predictor is also given. It implies that speed of the convergence to a certain image in a dynamic plot may be understood as an influence of collinearity.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 추계학술대회
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• pp.77-79
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• 2022

형태가 가변적인 영상을 감지하기 위해서는 많은 양의 관련 영상이 필요하다. 따라서 본 논문에서는 형태가 가변적인 영상 중 화재 영상을 GAN 알고리즘을 통해 증식시키고 이 영상을 이용해 AI 학습을 수행할 때의 검출률을 비교하여 GAN 알고리즘을 사용하여 증식된 이미지가 학습 데이터에 적합한지 분석하였다.

• International Journal of Aeronautical and Space Sciences
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• 제9권1호
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• pp.162-168
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• 2008

A design objective for variable stability flight control system is to develop a controller of in-flight simulation capability that forces the aircraft being flown to follow the dynamics of other aircraft. This paper presents a model-following variable stability control system (VSS) for in-flight simulation which consists of feedforward and feedback control laws, the aircraft dynamic model to be simulated, and switching and fader logics to reduce the transient effect between two aircraft dynamics. The separate design techniques for feedforward and feedback control law proposals are based on model matching and augmented linear quadratic (LQ) techniques. The system allows pilots to select and engage VSS mode, and when deselected, the aircraft reverts to the baseline flight control system. Both the baseline flight control laws and VSS control laws are computed continuously during flight. Initialization of the state values are necessary to prevent instability, since VSS control laws have integrators and filters in longitudinal, and lateral/directional axes. This paper demonstrates and validates the effectiveness and quality of VSS with F-16 models embedded in T-50 in-flight simulation aircraft.