• 대한기계학회논문집
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• 제19권1호
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• pp.150-160
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• 1995

The practical design and construction of a Stewart Platform-based unilateral universal hand-controller is presented. It is also presented that such a design concept could be implemented by developing a technical method of determining the forward kinematics of a Stewart Platform in real time. In this work, the forward kinematics of a Stewart Platform has been determined in real time using three additional displacement sensors which eliminate the computational burden of solving the forward kinematics described in nonlinear simultaneous equations. The workspace of the Stewart Platform via inverse kinematics has been analyzed numerically and used as a design guide for the determination of the mechanism dimensions such as the sizes of the upper and base platforms and the minimum and maximum lengths of the legs. The hardware of the hand-controller has been constructed and tested to demonstrate the feasibility of the design concept.

• 한국유체기계학회 논문집
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• 제12권4호
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• pp.7-13
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• 2009

The purposes of present work are to analyze the convective heat transfer with three-dimensional Reynolds-averaged Navier-Stokes analysis, and to optimize shape of the mixing vane using the analysis results. Response surface method is employed as an optimization technique. The objective function is defined as a combination of inverse of heat transfer rate and friction loss. Two bend angles of mixing vane are selected as design variables. Thermal-hydraulic performances have been discussed and optimum shape has been obtained as a function of weighting factor in the objective function. The results show that the optimized geometry improves the heat transfer performance far downstream of the mixing vane.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1997년도 추계학술대회논문집
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• pp.443-450
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• 1997

본 연구에서는 safework 소프트웨어를 이용하여 쾌적한 운전좌석에 대한 3차원 모델링을 하였다. 자동차 시트와 운전대의 조절 범위 및 레이아웃(layout), 그리고 운전자의 눈의 위치 등을 결정하기 위하여, 한국인과 미국인 체형의 95th percentile의 성인 남자와 5th percentile의 성인 여자, 그리고 50th percentile의 성인 남자에 대한 최적 운전상태에서의 엉덩이 점(hip point), 운전대 중심(steering wheel center), 눈의 위치(eye point) 등의 3차원상의 위치를 측정하였다. 인간의 모든 치수와 형태학적 윤곽 뿐만 아니라. 신체의 유동성, 기능적 제한 등이 충실히 반영된 safework 마네킹(mannequin)을 이용하 였으며, 여러 신체 부위의 복합적 움직임을 결정하는 역기구학(inverse kinematics)에 근거하여운전좌석을 모델링 하였다. Safework을 이용함으로써 기존의 마네킹이나 실물모형(mockup)의 제작에필요한 시간과 비용을 절약할 수 있을 뿐만 아니라, 인간의 신체 특성과 유사한 마네킹을 이용하여 인간과 환경사이의 인터페이스를 보다 효율적으로 모델링 할 수 있을 것이다.

• 제어로봇시스템학회논문지
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• 제7권7호
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• pp.589-596
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• 2001

In this paper, a new design methodology for the optimal control of nonlinear systems described by the TS(Takagi-Sugeno) fuzzy model is proposed. First, a new theorem concerning the optimal stabilizing control of a general nonlinear dynamic system is proposed. Next, based on the proposed theorem and the inverse optimal approach, an optimal controller synthesis procedure for a TS fuzzy system is given, Also, it is shown that the optimal controller can be found by solving a linear matrix inequality problem. Finally, the proposed method is applied to the attitude control of a rigid spacecraft to demonstrate its validity.

• 제어로봇시스템학회논문지
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• 제12권5호
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• pp.464-472
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• 2006

This paper presents the two degree-of-freedom (DOF) planar parallel mechanism, called the $2{\underline{R}}RR-RP$ manipulator, whose degree-of-freedom is dependent on an additional passive constraining leg connecting the base and the platform. First, the kinematic analysis of the mechanism is performed: the inverse and forward kinematic problems are analytically solved, the workspace is systematically derived, and all of the singular configurations are examined. Then, in order to determine the geometric parameters the optimization of the mechanism is performed considering its dexterity, stiffness, and space utilization. Finally, the kinematic performances of the optimized mechanism are evaluated through the comparison study to the conventional 5-bar parallel manipulator.

• 제어로봇시스템학회논문지
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• 제20권10호
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• pp.1023-1029
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• 2014

In this paper, we propose an SPDR (Smith Predictor for Disturbance Reduction) scheme to improve the temperature control by reduction of the disturbance in ROT process with measurement delay. The proposed controller is a combination of Astrom's modified Smith predictor with a disturbance reduction controller and a grey predictor. The grey prediction is used to calculate the inverse of the measurement delay and to predict future variations and tendencies of system output. The simulation results demonstrate the successful performance of the proposed disturbance reduction controller and enhance the robustness of the proposed control scheme.

• 한국군사과학기술학회지
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• 제6권3호
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• pp.122-130
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• 2003

This paper is concerned with a control allocation strategy using the dynamic inversion and the pseudo inverse control which generates the nominal control input trajectories, and autopilot design using time-varying control technique which is time-varying version of pole placement of linear time-invariant system for an agile missile with aerodynamic fin and thrust vectoring control. Control allocation of this paper is capable of extracting the maximum performance from each control effector, aerodynamic fin and thrust vectoring control, by combining the action of them. Time-varying control technique for autopilot design enhance the robustness of the tracking performance for a reference command. The main results are validated through the nonlinear simulation.

• 대한산업공학회지
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• 제22권3호
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• pp.459-471
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• 1996

This paper considers ramp tests for exponential lifetime distribution when there are limitations on test stress and test time. The inverse power law and a cumulative exposure model are assumed. Maximum likelihood (ML) estimators of model parameters and their asymptotic covariance matrix are obtained. The optimum ramp test plans are also found which minimize the asymptotic variance of the ML estimator of the log mean life at design constant stress. For selected values of the design parameters, tables useful for finding optimal test plans are given. The effect of the pre-estimates of design parameters is studied.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.254-256
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• 2005

This paper describes a design of a vector control module for AC motor using high density FPGA. In the proposed vector controller, the vector control blocks including inverse dq transform, space vector PWM and quadrature encoder pulse module are implemented in a FPGA using a VHDL. The simulation results are provided to show the validity of the proposed vector control module.

• 전력전자학회논문지
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• 제21권1호
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• pp.49-57
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• 2016

A modular multilevel converter is widely adapted for a high-voltage direct current power transmission system. This study proposes a design methodology for a novel digital control that mitigates the negative effects caused by time delay, including communication transport delay for a modular multilevel converter. The modeling and negative effect of time delay are analyzed theoretically in a frequency domain, and its compensation methodology based on an inverse model is described fully with practical considerations. The proposed methodology is verified through several simulation results using a modular 21-level converter system.