• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권2호
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• pp.77-82
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• 2002

This Paper describes the dynamic load simulator for high-speed elevator system, which can emulate 3-mass system as well as equivalent 1-mass system. In order to implement the equivalent inertia of entire elevator system the conventional simulators have generally utilized the mechanical inertia(flywheel) with large radius, which makes the entire system large and heavy. In addition, the mechanical inertia should be replaced each time in order to est another elevator system. In this paper, the dynamic load simulation methods using electrical inertia are Presented so hat the volume and weight of simulator system are greatly reduced and the adjustment of inertia value can be achieved easily by software. Experimental results show the feasibility of this simulator system.

• 융합신호처리학회논문지
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• 제2권3호
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• pp.65-72
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• 2001

일반적으로 관성시스템의 제어 문제는 결국, 시스템 자체에서 발생하는 진동을 최대한 억제하면서 빠른 시간에 출력이 기준입력을 추종하는데 있다. 이 경우 문제로 되는 것은 시스템의 모델링 과정에서 발생하는 플랜트의 불확실성과 parameter 변동이다. 여기서는 일반적인 강인한 제어기 설계 이론의 하나인 H$_{*}$ 이론이 가지는 단점인 제어기의 보수성을 극복하면서, 동시에 출력의 과도응답특성을 개선하기 위한 방법으로 H$_2$이론을 병용하고 이를 LMI 이론으로 해석하였다. 이 과정에서 3 관성시스템에 LMI 이론을 적용하기 위한 일반화플랜트의 모형을 제시하고 이것의 유효성을, 모델의 불화실성과 parameter변동을 동시에 고려한 simulation을 통하여 확인하였다.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2001년도 하계 학술대회 논문집(KISPS SUMMER CONFERENCE 2001
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• pp.129-132
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• 2001

본 논문은 3 관성시스템의 진동억제를 위한 강인한(robust) 제어기의 설계법을 제안하고 이를 simulation 을 통하여 확인하는데 있다. 일반적으로 관성 시스템의 제어 문제는 결국. 시스템 자체에서 발생하는 진동을 최대한 억제하면서 빠른 시간에 원하는 위치에 출력을 가져가는 데 있다. 이 경우 문제로 되는 것은 시스템의 모델링 과정에서 발생하는 플랜트의 불확실성과 parameter 변동이다. 여기서는 일반적인 강인한 제어기 설계 이론의 하나인 $H_{\infty}$ 이론이 가지는 단점인 제어기의 보수성을 극복하면서, 동시에 출력의 과도응답특성을 개선하기 위한 방법으로 $H_2$ 이론을 병용하고 이를 LMI 이론으로 해석하였다. 이 과정에서 3 관성시스템에 LMI 이론을 적용하기 위한 일반화플랜트의 모형을 제시하고 이것의 유효성을, 모델의 불확실성과 parameter변동을 동시에 고려한 simulation을 통하여 확인하였다.

• Nuclear Engineering and Technology
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• 제31권2호
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• pp.202-213
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• 1999

Effects of the rotary inertia of concentrated masses on the natural vibrations of fluid conveying pipes have been studied by theoretical modeling and computer simulation. For analysis, two boundary conditions for pipe ends, simply supported and clamped-clamped, are assumed and Galerkin's method is used for transformation of the governing equation to the eigenvalues problem and the natural frequencies and mode shapes for the system have been calculated by using the newly developed computer code. Moreover, the critical velocities related to a system instability have been investigated. The main conclusions for the present study are (1) Rotary inertia gives much change on the higher natural frequencies and mode shapes and its effect is visible when it has small value, (2) The number and location of nodes can be changed by rotary inertia, (3) By introducing rotary inertia, the second natural frequency approaches to the first as the location of the concentrated mass approaches to the midspan of the pipe, and (4) The critical fluid velocities to initiate the system unstable are unchanged by introduction of rotary inertia and the first three velocities are $\pi$, 2$\pi$, and 3$\pi$ for the simply supported pipe and 2$\pi$, 8.99, and 12.57 for the clamped-clamped pipe.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.332-334
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• 2001

This paper presents the simulator system of high-speed elevator system, which can be implemented as 3-mass system as well as equivalent 1-mass system. In order to implement the equivalent inertia of total elevator system, conventional simulator has generally utilized mechanical inertia (flywheel) with large radius, which makes the size and weight of total simulator system large. In addition, the mechanical inertia should be replaced each time in order to test the another elevator system. In this paper, the simulation method using electrical inertia is presented so that the volume and weight of simulator system are greatly reduced and the adjustment of value of the inertia can be achieved easily by software. Experimental results show the feasibility of this simulator system.

• Structural Engineering and Mechanics
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• 제40권5호
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• pp.637-654
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• 2011

The present paper studies the variation of the natural frequencies and mode shapes of rectangular plates carrying a three degree-of-freedom spring-mass system (subsystem), when the subsystem changes (stiffness, mass, moment of inertia, location). An analytical approach based on Lagrange multipliers as well as a finite element formulation are employed and compared. Numerically reliable results are presented for the first time, illustrating the convenience of using the present analytical method which requires only the solution of a linear eigenvalue problem. Results obtained through the variation of the mass, stiffness and moment of inertia of the 3-DOF system can be understood under the effective mass concept or Rayleigh's statement. The analysis of frequency values of the whole system, when the 3-DOF system approaches or moves away from the center, shows that the variations depend on each particular mode of vibration. When the 3-DOF system is placed in the center of the plate, "new" modes are found to be a combination of the subsystem's modes (two rotations, traslation) and the bare plate's modes that possess the same symmetry. This situation no longer exists as the 3-DOF system moves away from the center of the plate, since different bare plate's modes enable distinct motions of the 3-DOF system contributing differently to the "new' modes as its location is modified. Also the natural frequencies of the compound system are nearly uncoupled have been calculated by means of a first order eigenvalue perturbation analysis.

• 로봇학회논문지
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• 제17권3호
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• pp.347-352
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• 2022

The paper presents how to update impedance control parameters for dual-arm manipulators using EMG signals and motions of the operator. Since the hand motions of the dual-arm are modeled to be the mass-spring-damper system in this paper, the impedance parameter update method is an important issue to reflect the operator's force. However, task space inertia to be used as the mass parameter goes to infinity if the manipulator approaches a kinematic singularity. To alleviate this issue, the impedance (stiffness and damping) parameters are divided with a diagonal element of the task space inertia. Also, the stiffness and damping matrices are updated using the normalized EMG signals captured from the operator's forearm. Through this process, the motion of the dual-arm manipulator is more stabilized even though it approaches the kinematic singularity.

• 한국안전학회지
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• 제13권1호
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• pp.3-12
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• 1998

On the stability of the cantilever beam subjected to a follower force at the free end, the influences of the translational spring and the moment of inertia of a tip mass at the free end have been studied by numerical methods. The centroid of a tip mass is offset from the free end of a Beam and is located along its extended axis to vary the value of moment of inertia of a tip mass. It is proved that as the constants of a spring supporting the free end are augmented, the critical flutter loads of the above system decrease, whereas they increase without a tip mass.

• 한국정밀공학회지
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• 제8권4호
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• pp.107-117
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• 1991

The dynamic stability problem of nonconservative system is one of the important problems. In this study, flexible missile with mass variation is regarded as a free Timoshenko beam subjected to a controlled follower force. The stability was studied numerically through the finite element method. Through the study, the obtained results are as follows: [1] Without force direction control (1) In the case of no mass reduction, the existence of concentrated mass increases critical follower force. (2) Mass reduction rate of the beam slightly effects on the change of critical follower force. [2] With force direction control (1) Shear deformation parameter S contributes insignificantly to the force at instability when $S{\geq}10^4$. (2) With mass variation, increase of concentrated mass increases critical follower force at instbility. (3) The type of promary instability is determined by the sensor location.

• 전자공학회논문지T
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• 제35T권3호
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• pp.76-86
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• 1998

2관성 공진(TMS: Two-Mass Spring) 시스템은 비틀림 진동을 다루기 위하여 고려할 수 있는 가장 간단한 모델이다. 이러한 시스템은 비틀림 진동을 억제하며, 원하는 특성을 달성하기 위한 제어기 설계가 요구된다. 본 논문에서는 2관성 공진 시스템에 대하여 상태 피드백을 고려하고, 각 상태가 응답성능에 미치는 영향을 살펴본다. 이 결과와 상태 피드백의 이득을 이용하여 제어기의 설계 매개변수와 LQ 및 H/sub ∞/ 제어의 하중함수 결정에 대한 기본 지침을 제시한다.