• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.2
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• pp.122-128
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• 2010

This paper presents vibration control performance of active engine mount system installed with the magneto-rheological(MR) mount and the piezostack mount. The performance is evaluated via hardware-in-the-loop-simulation(HILS) method. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three point mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. As a second step, sliding mode controller(SMC) is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds(wide frequency range) using HILS method and presented in time and frequency domain.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.237-242
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• 2008

This paper presents vibration control of an active hybrid engine mount featuring magneto-rheological (MR) fluid and a piezostack actuator. On the basis of the conventional passive rubber mount, MR fluid is adopted to improve isolation performance at resonant frequencies, whereas the piezostack actuator is adopted for performance improvement at non-resonant frequencies, especially at high frequencies. Based on some particular practical requirements of engine mounts, the proposed mount is designed and manufactured. The characteristics of rubber element, piezostack actuator and MR fluid are verified for system analysis and controller synthesis. The model of the proposed mount with a supported mass (engine) is established. In this work, a sliding mode controller is synthesized for the mount system to reduce vibrations transmitted from the engine in a wide frequency range. Computer simulations are performed to evaluate the performances of the proposed active engine mount in time and frequency domains.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.444-449
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• 2009

An engine is one of the most dominant noise and vibration sources in vehicle systems. Therefore, in order to resolve noise and vibration problems due to engine, various types of engine mounts have been proposed. This work presents a new type of active engine mount system featuring a magneto-rheological (MR) fluid and a piezostack actuator. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three points mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. In the configuration of engine mount system, two MR mounts are installed for vibration control of roll mode motion whose energy is very high in low frequency range, while one piezostack mount is installed for vibration control of bounce and pitch mode motion whose energy is relatively high in high frequency range. As a second step, linear quadratic regulator (LQR) controller is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds (wide frequency range) and presented in time domain.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.6
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• pp.583-590
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• 2009

An engine is one of the most dominant noise and vibration sources in vehicle systems. Therefore, in order to resolve noise and vibration problems due to engine, various types of engine mounts have been proposed. This work presents a new type of active engine mount system featuring a magneto-rheological (MR) fluid and a piezostack actuator. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three points mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. In the configuration of engine mount system, two MR mounts are installed for vibration control of roll mode motion whose energy is very high in low frequency range, while one piezostack mount is installed for vibration control of bounce and pitch mode motion whose energy is relatively high in high frequency range. As a second step, linear quadratic regulator (LQR) controller is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds(wide frequency range) and presented in time domain.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.11
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• pp.1150-1156
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• 2008

This paper presents vibration control of an active hybrid engine mount featuring a magneto-rheological(MR) fluid and a piezostack actuator. The MR fluid is adopted to improve isolation performance at resonant frequencies, while the piezostack actuator is adopted for performance improvement at non-resonant frequencies, especially at high frequencies. Based on some particular practical requirements of engine mounts, the proposed mount is designed and manufactured. The characteristics of rubber element, piezostack actuator and MR fluid are verified for system analysis and controller synthesis. The dynamic model of the proposed mount with a supported mass (engine) is established. In this work, a sliding mode controller is synthesized for the mount system to reduce vibrations transmitted from the engine in a wide frequency range. Computer simulations are performed to evaluate control performances of the proposed active engine mount in time and frequency domains.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.321-322
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• 2011

차세대 저장매체로 각광받고 있는 BPRAM을 이용해, NAND Flash memory의 결점을 보완하고자 하는 많은 연구들이 진행되고 있다. 본 논문에서는 BPRAM과 NAND Flash를 이용하여, 계층적 스토리지에 사용하는 하이브리드 파일 시스템인 Compressing Metadata File System(CMFS)을 개발하였다. CMFS는 Mount time에 필요한 메타데이터를 BPRAM에 저장하여 마운트 시간을 줄이고, 메타데이터를 Update하기 위한 Overhead를 줄이기 위해 부분 갱신 기법을 개발하였다. 또한 메타데이터의 저장을 위해 필요한 BPRAM의 용량를 줄이기 위해 메타데이터를 경량화 및 압축하고, 압축률을 높이기 위해 Hybrid Coding 압축기법을 개발하여 적용한다. Marvel PXA320(806MHz) 보드를 이용하여 CMFS의 성능을 측정하였으며, 타 압축 기법보다 높은 메타데이터의 압축률을 보였다.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.12
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• pp.107-116
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• 2008

The excitation force of a powertrain is one of major sources for the interior noise of a vehicle. This paper presents a novel approach to predict the interior noise caused by the vibration of the power rain by using the hybrid TPA (transfer path analysis) method. Although the traditional transfer path analysis (TPA) is useful for the identification of powertrain noise sources, it is difficult to modify the structure of a powertrain by using the experimental method for the reduction of vibration and noise. In order to solve this problem, the vibration of the power rain in a vehicle is numerically analyzed by using the finite element method (FEM). The vibration of the other parts in a vehicle is investigated by using the experimental method based on vibrato-acoustic transfer function (VATF) analysis. These two methods are combined for the prediction of interior noise caused by a power rain. Throughout this research, two papers are presented. This paper presents a simulation of the excitation force of the power rain exciting the vehicle body based on numerical simulation. The other paper presents a prediction of interior noise based on the hybrid TPA, which uses the VATF of the car body and the excitation force predicted in this paper.