• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.615-616
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• 2013

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1993.10a
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• pp.117-124
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• 1993

본 연구에서는 공기스프링을 능동요소로 사용한 방진대를 1자유도 및 2자유도로 모델링하여 이론해석을 수행하였고, 이에 따른 컴퓨터시뮬레이션과 실험을 통하여 이론의 타당성을 검증하였다. 다음으로 공기스프링 방진대의 방진성능 향상을 위하여 비례제어밸브, 컴퓨터, 측정센서 등을 이용하여 공기 스프링내의 공기압력을 능동적으로 조절할 수 있는 제어계를 구성한 후, 최적제어 및 퍼지제어 알고리즘을 적용하여 상태귀환 제어를 실시하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.132-137
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• 2000

Recently, a severe noise problem was encountered during a shop test of large scale vertical motor. In order to identify the noise characteristics and propose the countermeasure, a variety of experiments such as sound excitation test and contribution analysis was earned out in addition to ordinary noise and vibration measurements. The results showed that the severe noise level was dominated by an acoustic resonance phenonmenon in the cooler housing and higher sound power of outer fan. Through proper treatments, the noise level could be acceptable.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.629-635
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• 2000

Vibrational characteristics and tension fluctuation of a translating wire in WEDM are the main problems to deteriorate the cutting accuracy and processing performance. In this paper, we analyze natural frequencies of the wire used in WEDM, both theoretically and experimentally. To reduce the tension variation of the wire. which directly affects cutting performance. we have designed a simply tension reduction device using springs and rollers. It is shown that tension fluctuation is reduced about 25% using the passive tension controller.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.12
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• pp.1330-1337
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• 2004

In this study, the equations of motion of a rigid rotor supported by magnetic bearings are derived via Hamilton's principle, and transformed to a state-space form for control purpose. The optimal motion control of rotor magnetic bearing system based on the LQR(linear quadratic regulator) theory is addressed. New schemes related to the selection of the state weighting matrix Q and the control weighting matrix R involved in the quadratic functional to be minimized are proposed. And the robust control of the system with an LMI(linear matrix inequality) based H$_{\infty}$ theory is dealt with in this paper. Loop shapings of TFM (transfer function matrix) are used to increase the performance of control capability of the system. The control abilities of LQR and H$_{\infty}$ controller are compared by simulation and experimental tests and show that the capability of H$_{\infty}$ controller is superior to that of LQR.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.734-739
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• 2003

Many types of smart materials and control laws are available to actively adjust the structure from various external disturbances. Usually, a certain type of control laws to activate a specific smart material is well established, but the effectiveness of the control scheme is limited by the choice of the smart materials and the responses of the structure. ER fluid is adequate to provide relatively large control force, on the other hand, the PZT patches are suitable to provide small but arbitrary control forces at any point along the structure. It was found that active vibration control mechanism using ER fluid failed to suppress the excitation off the resonant frequency with changed structural characteristics along the frequency response function of the closed loop of the control system. To compensate this additional peak of the closed loop system, PPF control using PZT as an actuator is added to construct a hybrid controller.

• Smart Structures and Systems
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• v.10 no.1
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• pp.33-46
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• 2012

To reduce the vibration of cable-stayed bridges, conventional magnetorheological (MR) damper control system (CMRDS), with separate power supply, sensors and controllers, is widely investigated. In this paper, to improve the reliability and performance of the control system, one adaptive MR damper control system (AMRDS) consisting of MR damper and piezoelectric energy harvester (PEH) is proposed. According to piezoelectric effect, PEH can produce energy for powering MR damper. The energy is proportional to the product of the cable displacement and velocity. Due to the damping force changing with the energy, the new system can be adjustable to reduce the cable vibration. Compared with CMRDS, the new system is structurally simplified, replacing external sensor, power supply and controller with PEH. In the paper, taking the N26 cable of Shandong Binzhou Yellow River Bridge as example, the design method for the whole AMRDS is given, and simple formulas for PEH are derived. To verify the effectiveness of the proposed adaptive control system, the performance is compared with active control case and simple Bang-Bang semi-active control case. It is shown that AMRDS is better than simple Bang-Bang semi-active control case, and still needed to be improved in comparison with active control case.

• Tunnel and Underground Space
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• v.2 no.1
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• pp.102-115
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• 1992

Blasting operations associated with rock excavation work may have an environmental impact in nearby structures or human beings. With the increase of construction work in urban areas, vibration problems and complaints have also increased. In order to determine the optimum design parameters for safe blast, it is essential to understand blast mechanism, design variables involved in blast-induced damage, and their effects on the blasting results. This paper deals with the characteristics of ground vibrations, air blast and fly rock caused by blast, including the general method of establishing the vibration predictors, and damage criteria suggested by various investigators. The results of field measurements from open pit mine and tunnel construction work are discussed. Basic concepts of how to design blast parameters to control the generation of ground vibrations, air blast and fly rock are presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.280-281
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• 2008

In pursuit of decreasing noise and vibration, the electromagnetic active control mount(ACM) is developed which is corresponding with the tendency of greater fuel efficiency, higher engine power and lower lightweight vehicle. In process of developing the ACM, making patent searches and benchmarking are performed first, and then robust mount design which is reflected on the users' demand through Design For Six Sigma(DFSS) is carried out. The manufactured prototype of ACM is tested in various environmental conditions for the purpose of ensuring the performance quantitatively.

• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.753-758
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• 2012

This paper deals with the analysis of vibration and noise sources in a modular-type SPM fractional-slot motor. To reduce cogging torque, torque ripple and unequal radial force, which are the main causes of the electromagnetic vibration, the optimal shape of notch and magnet are designed.