• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.1269-1272
• /
• 1996

Several input shaping techniques are suggested to reduce the vibration of a flexible manipulator. The theories of typical 4 methods(Singer, Tuttle, Feddema, Zuo) are explained and are tested by the experiment of one link flexible manipulator. Zuo's method is the best of all with respect to its robustness.

• Proceedings of the KIPE Conference
• /
• 1998.07a
• /
• pp.342-346
• /
• 1998

The brushless DC motor with trapezoidal back emfs has torque ripple due to phase commutation. The torque ripple generates noise and vibration and cause errors in position control so this makes the brushless DC motor less suitable for high performance servo applications. In this paper, we propose a new current control method to reduce the torque ripple due to commutation, when the unipolar PWM method is applied for the phase current control of brushless DC motor.

• Smart Structures and Systems
• /
• v.19 no.6
• /
• pp.665-678
• /
• 2017

In this paper the tuned mass-damper-inerter (TMDI) is considered for passive vibration control and energy harvesting in harmonically excited structures. The TMDI couples the classical tuned mass-damper (TMD) with a grounded inerter: a two-terminal linear device resisting the relative acceleration of its terminals by a constant of proportionality termed inertance. In this manner, the TMD is endowed with additional inertia, beyond the one offered by the attached mass, without any substantial increase to the overall weight. Closed-form analytical expressions for optimal TMDI parameters, stiffness and damping, given attached mass and inertance are derived by application of Den Hartog's tuning approach to suppress the response amplitude of force and base-acceleration excited single-degree-of-freedom structures. It is analytically shown that the TMDI is more effective from a same mass/weight TMD to suppress vibrations close to the natural frequency of the uncontrolled structure, while it is more robust to detuning effects. Moreover, it is shown that the mass amplification effect of the inerter achieves significant weight reduction for a target/predefined level of vibration suppression in a performance-based oriented design approach compared to the classical TMD. Lastly, the potential of using the TMDI for energy harvesting is explored by substituting the dissipative damper with an electromagnetic motor and assuming that the inertance can vary through the use of a flywheel-based inerter device. It is analytically shown that by reducing the inertance, treated as a mass/inertia-related design parameter not considered in conventional TMD-based energy harvesters, the available power for electric generation increases for fixed attached mass/weight, electromechanical damping, and stiffness properties.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.10 no.6 s.52
• /
• pp.67-77
• /
• 2006

Seismic activity of Korea is not so high as that of Japan or California and most of the structures were designed without considering the influence of earthquakes until the first seismic design code was enforced in 1988. Therefore, it was very hard to find seismically isolated structures in Korea until 1980's. Korean engineers assumed that the seismic isolation or vibration control would be useful only in a high seismicity region while such technologies can be quite useful in a low seismicity region for the efficient reduction of earthquake damages. Recently, Korean engineers began to have interest in the seismic isolation or vibration control and applied it to some important structures such as LNG storage tanks, many bridges and several buildings. However, design codes are not defining such useful advanced technologies for the design of building structures and several projects employing seismic isolation or vibration control in the design of structures had difficulties in obtaining construction permit from the local government. Therefore, it is an urgent requirement to introduce these advanced technologies in the seismic design code.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2010.10a
• /
• pp.421-426
• /
• 2010

With hydraulic noise test facility, a variety of tests were performed to investigate the pulsation pressure generation mechanism and its transmission characteristics and to derive the noise control methodology. Many experiments were carried out by changing average pressure, flow rate, pump speed, hose length and MCV spool condition. From the test results, the correlations between pulsation pressure and other design parameters, such as static pressure, flow rate and MCV spool opening area and length of hose, were found out. And also each contribution factors were evaluated from the regression analysis. By changing hose length, the pulsation pressure resonance phenomenon was investigated. In order to find out the pulsation pressure reduction measures pulsation pressure analysis, such as pulsation pressure of hydraulic pump itself and pulsation pressure of hydraulic system, by using AMESim were studied. In addition hydraulic silencer was developed based on the Helmholtz resonator. And its performance was evaluated by installing the silencer at the excavator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.1313-1316
• /
• 2001

Generally, container carrier has larger engine than other commercial vessels and the engine casing is located in accommodation space. Therefore, the noise levels of cabins and engine room could be exceeded the specified noise limits and might be an annoyance to crews, and which can result in poor ship quality. Main subject of this study is to predict noise levels of the 4,500 TED container carrier by statistical energy analysis method in order to comply with contracted noise limits and to compare with the measured values. Additionally, through the contribution analysis of noise sources to each cabins, and appropriate countermeasures are proposed and the reduction effect of each noise control measure is studied by the analysis method. This study will contribute to reduce the noise levels of similar vessel.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.11b
• /
• pp.204-209
• /
• 2002

A PDP(Plasma Display Panel) module consists of a discharge panel, a SMPS(Switched Mode Power Supply) for power supply, driving boards for panel control, and a logic board. Driving boards supply high voltage pulses to induce glow discharge in the PDP panel. The electrical pulses excite the circuit elements and subsequently generate acoustic noises. The main sources of the noise in the circuit are the transformer of SMPS and the power MOSFET(Metal Oxide Semiconductor Field Effect Transistor) of driving boards, and the heat sinks often amplify the noise level. The reduction of the acoustic noises was achieved by modifying both the structural and circuit elements. The structural method was executed by the improvement of heat sinks. The optimization of SMPS and condensers was carried out for the circuit elements.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.45 no.1
• /
• pp.123-130
• /
• 1996

Due to high payload capacity and high length-to -cross-section ratio requirements, long-reach manipulator systems are expected to exhibit significant structural flexibility. To avoid structural vibrations during operations, various types of input shaping filtering methods have been investigated. A robust notch filtering method and an impulse shaping filtering method were investigated and implemented. In addition, two very different approaches have been developed and compared. One new approach, referred to as a

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.738-741
• /
• 2003

In general, the essential requirement for cruisers or car ferries is the reduction in noise to ensure high quality and comfort. Recently, the Ro-Ro Passengers Ferry (ROPAX) was built in Hyundai Heavy Industries. In order to minimize the noise levels, careful attention have to De paid by the special committee of experts from the initial design stage to the sea trial. Proper countermeasures, considering the characteristics of sources and receiver spaces, were applied from the noise prediction and various experiment results. Finally, this ship was successfully delivered with excellent noise properties. This paper describes the procedure of noise analysis, the countermeasures of noise control, and the measurement results of the sea trial. Onboard noise analysis had been carried out by statistical energy analysis program and outdoor noise prediction program based on ISO9614. The prediction results are in good agreements with the measurement results. The technology to minimize the noise levels for cruisers or car ferries has been established throughout the construction of this ship.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.1
• /
• pp.83-91
• /
• 2010

In this paper, the feasibility of the cost function having two control factors were discussed in compared to two others which has one different control factor respectively. As of the control factors, the dynamic response of a discrete system and the vibrational intensity at the reference point which is the connecting point of a discrete system to a flexible beam were controlled actively by the control force obtained from the minimization of the cost function. The method of feedforward control was employed for the control strategy. The reduction levels of the dynamic response of a discrete system and the vibrational intensity at a reference point, and also the input power induced by the control force were evaluated numerically in cases of the three different cost functions. In comparison with the results obtained from the cost functions of one control factor, which is the dynamic response or the vibrational intensity, in most cases of the cost function of two control factors the better or similar results were obtained. As a conclusion, it is surely noted that both the dynamic response and the vibrational intensity of the vibrating system be controlled up to the expected level by using the single cost function having two control factors.