• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.83-90
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• 2013

This paper describes advanced brushless DC motor drive without position sensor for home appliances with compressor to reduce the pulsating currents and vibration. The proposed method limits the motor currents during starting period and reduces commutation torque ripple during sensorless operating period. Experimental results show that the proposed method implemented in an inverter for a BLDC motor driven compressor considerably reduces not only the pulsating currents but also vibration of the home appliances.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.45-50
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• 1995

본 연구에서는 기존에 널리 사용되고 있는 스카이훅 제어 알고리즘(skyhook control algorithm)[3]을 바탕으로 확장 개발된 모드 스카이훅 제어(mode skyhook control) 개념 및 주파수 감응식 제어(frequency dependent control)개념[4][5]을 실용화하기 위하여 응답속도가 20msec이하의 비교적 빠른 응답 속도를 갖는 전자기식 작동기 (electro-magnetic actuator)에 의해 가변되는 4단 반능동형 가변 댐퍼 시스템을 개발한 후, 다음과 같은 성능의 향상을 시험결과를 통하여 보이고자 한다. -저속에서의 승차감 향상과 고속에서의 주행 안정성 향상 -커브 주행 또는 급격한 핸들 작동시의 롤안정성 (rolling stability) 향상 -제동 및 급발진시의 차체 피칭 운동 방지 (anti-dive, anti-squat)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.278-281
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• 2004

Multiple sound sources are controlled to enhance sound power within a zone of interest. The problem of enhancing acoustic variable can be regarded as an optimization problem, which seeks an optimal control input that maximizes the acoustic variable. It should be noted that enhancing sound power of a selected region requires both the magnitude and direction to be controlled. For this reason, two kinds of cost functions that can represent the spatially distributed intensity are defined. Theoretical formulation shows the possibility of sound power control in a zone, and the detailed procedures of the proposed method are validated by numerical simulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.269-273
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• 2000

This paper describes Active Noise Control (ANC) using Discrete Wavelet Transform (DWT) Domain Least Mean Square (LMS) Method. DWT-LMS is one of the transform domain input decorrelation LMS and improves the convergence speed of adaptive filter especially when the input signal is highly correlated. Conventional transform domain LMS's use Discrete Cosine Transform (DCT) because it offers linear band signal decomposition and fast transform algorithm. Wavelet transform can project the input signal into the several octave band subspace and offers more efficient sliding fast transform algorithm. In this paper, we propose Wavelet transform domain LMS algorithm and shows its performance is similar to DCT LMS in some cases using ANC simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.614-619
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• 2012

A LQG/LTR(Linear Quadratic Gaussian/Loop Transfer Recovery) controller with an integrator is designed to control the electro-hydraulic positioning system. Without considering the nonlinearity in the dead-zone, computer simulations are performed and show good performances and tracking abilities with the feedback controller based on the linear system model. However, the performance of the closed loop hydraulic positioning system shows big steady-state error in real system because of the dead-zone. In this paper, the feedback controller with a nonlinear compensator is introduced to overcome the dead-zone phenomenon in hydraulic systems. The inverse dead-zone as a nonlinear compensator is used to cancel out the dead-zone phenomenon. Experimental tests are performed to verify the performance of the controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.388-393
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• 2012

Acoustic brightness and contrast control are promising techniques for manipulating acoustic energy over selected zones of interest using loudspeaker arrays. In this paper, the fundamental theory and concept of the brightness and contrast control is reviewed. The similarity and difference of two different strategies are explained in terms of the constraint required to determine a unique solution among many possible candidates. The application examples and recent progresses of the brightness and contrast control are presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.483-484
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• 2010

Unit cabin means room, which is installed in the high value ship such as drill ship and FPSO, after pre-assembled. In order to develop the noise control design for a unit cabin, a variety of acoustic tests such as sound absorption, transmission, and radiated noise measurements were carried out by using the mock-up of living quarter. From the tests, it was found out that the combined noise level of a unit cabin could be dominated by the radiated noise from wall panel in low frequency range and the design guidelines for the noise control of unit cabin were fully established, such as the improvement of sound transmission loss between the cabin and corridor, and radiated cabin noise reduction.

• Smart Structures and Systems
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• v.19 no.5
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• pp.567-576
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• 2017

Design of piezoelectric energy harvester for a wide operating frequency range is a challenging problem and is currently being investigated by many researchers. Widening the operating frequency is required, as the energy is harvested from ambient source of vibration which consists of spectrum of frequency. This paper presents a new technique to increase the operating frequency range which is achieved by designing a harvester featured by a propped cantilever beam with variable over hang length. The proposed piezoelectric energy harvester is modeled analytically using Euler Bernoulli beam theory and the effectiveness of the harvester is demonstrated through experimentation. The results from analytical model and from experimentation reveal that the proposed energy harvester generates an open circuit output voltage ranging from 36.43 V to 11.94 V for the frequency range of 27.24 Hz to 48.47 Hz. The proposed harvester produces continuously varying output voltage and power in the broadened operating frequency range.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.212-217
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• 2011

A scheduling technique for the improvement of yaw motion stability in in-wheel motor vehicle is proposed. Normally vehicle velocity is controlled via conventional PID method. When vehicle is encountered with different road conditions on left and right hand sides, unstable yaw motion is induced due to the driving force difference in both wheels. In this paper a scheduling formular for control gain is derived in terms of experimental results to generate proper counter control action. Simulation result reveals its effective performance in yaw control of in-wheel vehicle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.115-119
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• 2011

Instead of very expensive sound record and professional measurement microphones the low cost Surface Mounted Device (SMD) microphones are proposed for practical barrier ANC system. FRF of the microphones and theirs sensitivity to the wind interferences are evaluated in semi anechoic chamber. The improvement of feedforward algorithm noise reduction index was evaluated based on measured coherence function between tested SMD and reference microphone. Test was performed at various wind speed from 1 m/s to 5 m/s.