• 한국소음진동공학회논문집
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• 제13권4호
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• pp.274-280
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• 2003

If a sinusoidal excitation force moves back and forth along a structure with a certain frequency, the structure will be excited with the difference frequency of these two frequencies. A low frequency vibration shaker has been developed using this force frequency shifting without actually moving a shaker The shaker consists of an ordinary eccentric mass shaker, a plate, constant springs, and time varying dampers. The dampers are turned on and off in a sequential manner to simulate a traveling slide of an excitation force. The operation of the shaker is simulated by solving the equations of motion of the shaker. Characteristics of the shaker have been found and they can be utilized to design efficient low frequency shakers.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.182-186
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• 2002

If a sinusoidal excitation force moves back and forth along a structure with a certain frequency, the structure will be excited with the difference frequency of these two frequencies. A low frequency vibration shaker has been developed using this force frequency shifting without actually moving a shaker. The shaker consists of an ordinary eccentric mass shaker, a plate, constant springs, and time varying dampers. The dampers are turned on and off in a sequential manner to simulate a traveling slide of an excitation force. The operation of the shaker is simulated by solving the equations of motion of the shaker. Characteristics of the shaker have been found and they will be utilized to design efficient low frequency shakers.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.324.2-324
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• 2002

If a sinusoidal excitation force moves back and forth along a structure with a certain frequency, the structure will be excited with the difference frequency of these two frequencies. A low frequency vibration shaker has been developed using this force frequency shifting without actually moving a shaker. The shaker consists of an ordinary eccentric mass shaker, a plate, constant springs, and time varying dampers. The dampers are fumed on and off in a sequential manner to simulate a traveling slide of an excitation force. (omitted)

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.174.3-174
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• 2001

Electric power collection is one of the most important factors for the high-speed trains' operation. For the stable current collection, the contact wire of a catenary and the panhead of a pantograph should maintain a constant contact each other. In this paper, the catenary was modeled as a spring with time-varying stiffness from the point of a pantograph moving along the catenary, and the pantograph was modeled as a 3-D.O.F. mass-spring-damper system. Using the adaptive control method, the desired control performance could be obtained with the modeling errors and the time varying parameters. Also the state estimator was used considering the difficulty of applying the sensors obtaining feedback signals. Simulations were accomplished in various ...

• 한국구조물진단유지관리공학회 논문집
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• 제16권3호
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• pp.60-66
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• 2012

본 논문에서는 무선 센서 네트워크를 이용한 피드백 진동제어 시스템을 구성하고, 모형 구조물을 대상으로 구성된 시스템의 진동제어효과를 실험적으로 검증하고자 하였다. 이를 위하여 본 논문에서는 블루투스 기반의 무선 I/O 센서 시스템과 스마트 재료를 사용한 전단형 MR 댐퍼를 개발하고, 또한 일정한 크기의 정현파형을 발생시키는 가진기 및 모형 단순보 구조물을 이용하여 피드백 진동제어 시스템의 실험�V을 구성하였다. 진동제어 실험은 가진기를 이용해 보의 1/4 등분점에서 일정하게 가진한 상태에서, 보 중앙점에 수직방향으로 설치된 MR 댐퍼를 이용해 진동을 제어하였으며, 보의 2/4 등분점에서의 가속도 응답을 획득하여 제어효과를 평가하였다. 이때, 제어명령은 보 중앙점에 무선 I/O 센서 노드를 설치하고, 여기서 획득된 가속도 응답이 일정 크기 이상일 경우에 설정된 범위의 전압신호를 MR 댐퍼로 출력하도록 설정하였다. 최종적으로 본 논문에서 구성된 무선 센서 네트워크 기반의 실시간 피드백 진동제어 시스템은 비록 제한적인 명령 체계에서 검증되었지만, 실시간적으로 목적된 제어명령의 발생시킴으로써 구조물의 진동을 효과적으로 감소시키는 것을 확인하였고, 추후 다양한 준능동 제어 알고리즘을 적용한 구조적 응답제어시스템으로의 활용 가능성을 제시하였다.

• 한국해양공학회지
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• 제29권4호
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• pp.283-290
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• 2015

This paper presents the results of a numerical study on the towing characteristics of a barge under various wind conditions. First, stability criteria, including the wind force, were derived based on the linear motion equations of a towed vessel. The effect of the wind force on the towing stability was investigated using stability criteria. Next, towing simulations were carried out using a nonlinear time-domain simulation method. In this case, the towline was modeled as a simple spring-damper, and the wind force was computed using the wind coefficient from CFD calculations. Simulations were conducted for a barge under a constant towing speed and constant wind speed conditions. The effect of the wind direction on the slewing motion was also observed. In addition, a series of numerical simulations using variable wind speeds were performed for the present barge with and without a skeg.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.5-7
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• 2007

This paper deals with design and analysis of thrust magnetic bearing for 300HP class high speed motor. Using the solutions obtained from equivalent magnetic circuits, we predicts the electromagnetic characteristics such as thrust, time constant and power loss according to design parameters. And then, using non-linear finite element analysis, a detailed design is performed considering saturation in order to meet requirements.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.689-693
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• 1997

This paper deals wth the impact and the transient analysis of the impact absorbing system consist of double damping. piston and sprlng system in spreader to increaas efficlcncy of it. It shows the optimum damping coefficient and spring constant under the limited stroku of Impact absorbing system using for crane spreader and the optimum condition of impact absorbing system causing certain reaction force as time. which is characteristic of dashpot and rubber. This system absorbed 11.5 and 88.5 % impact energq at the spring and the damper respectively.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.85.3-85
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• 2002

In this study, we tried to investigate the impedance characteristic of human arm in a cooperative task. Human arm was moved in a desired trajectory. The motion was actuated by a 1 degree-of-freedom robot system. As the muscle is mechanically analogous to a spring-damper system, a second-order equation was considered as the model for arm dynamics. In the model, inertia, stiffness and damping factor were considered. The impedance parameter was estimated from the position and torque data obtained from the experiment and based on the "Estimation of Parametric Model". It was found that the inertia is almost constant over the operational time. The damping factor and stiffness were high...

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
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• pp.251-258
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• 1999

The vibration control of bridge is studied considering the vibration characteristics of the Korean-type high-speed railway bridge. Fast nonlinear analysis is adopted as time integration method and the bridge and the train are modeled by FEM and sequentially moving constant forces respectively. Additional damping mechanism is indispensable to the Korean-type high-speed railway bridge because resonance vibration is excited under the maximum design speed. The optimal position and capacity of the damper is studied through the parametric studies, Transient vibration of the bridge is effectively controlled by such additional dampers which means that dampers play a role as structural damping. And also the maximum response of the bridge is reduced. Therefore it is verified that the increase of expected service life and the improvement of serviceability can be obtained through dampers.