• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.276-277
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• 2008

Recently active engine mounting system is developed for improvement of vehicle NVH performance which follow the development of high efficient powertrain and lightweight vehicle body. The most important part in the development of active engine mounting system is implementation of optimal engine mounting system to apply active engine mount. In this paper engine mounting systems including active engine mount are considered and their performance is predicted using engine mounting system analysis tool. Then optimal mounting system for active engine mount is proposed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.2 s.173
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• pp.370-377
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• 2000

This paper presents a mixed-mode type ER(electro-rheological) engine mount, and its vibration control performance for a passenger vehicle is presented. The field-dependent yield stress of a transfo rmer oil-based ER fluid is empirically distilled in both shear and flow modes. This is then incorporated with the governing equation of motion of the proposed mixed-mode(shear mode plus flow mode) type engine mount. The damping force is analyzed with respect to the intensity of the electric field and design parameters such as electrode gap. Subsequently, the ER engine mount which is equivalent to the conventional hydraulic engine mount in terms of the damping level is designed and manufactured. Both computer simulation and experimental test are undertaken in order to evaluate vibration isolation performance. In addition, this performance is compared with that of the conventional hydraulic engine mount.

• Journal of Biosystems Engineering
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• v.29 no.5 s.106
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• pp.385-394
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• 2004

The objectives of this study were to investigate the effectiveness of rubber as an engine mount of walking-type cultivators and to determine its optimal spring constant and damping coefficient using a dynamic simulation of the engine mount system. Four different types of rubber mounts were tested to determine their spring constants and damping coefficients, and the best type was selected for the isolation of the engine vibrations transmitted to the handle. The total vibration levels transmitted to the handle when the rubber mounts weren't installed were 17.52 $m/s^2$. The total vibration levels transmitted to the handle when the rubber mounts were installed were 10.69 $m/s^2$ for Stripe 1, 11.33$m/s^2$ for Stripe 2, 10.92$m/s^2$ for Stripe 3 and 14.19$m/s^2$ for Hive, respectively, resulting in an average of $30\%$ reduction when compared with that without the engine mount. A dynamic model of the cultivator's engine-mount system and its simulation program were developed and verified. A method was proposed to determine the optimal spring constant and damping coefficient of the engine-mount system. It was found from the simulation that a spring constant of 4,100 kN/m and the largest damping coefficient were the most effective for the vibration isolation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.7
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• pp.654-661
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• 2013

The dynamic characteristics of a free-piston stirling engine(FPSE) with regard to the working frequency is investigated from theoretical and experimental studies. The FPSE is modeled as a two degree-of-freedom linear vibration system. A theoretical expression on the working frequency is derived from the instability condition for self-excitation based on the linear vibration model. A ${\gamma}$-type free-piston stirling engine is fabricated for experimental studies, and its working frequency is measured on various heater temperatures. Comparisons between the theoretical and experimental results reveal that the working frequency of the test FPSE depends on both the temperature of the compression space and the temperature difference between the expansion and compression spaces.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.243-246
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• 2012

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.44-50
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• 2002

Theoretical analysis on the transient torsional vibration was started from early 1960's for high power synchronous motor application. As for marine engineering, simulation and measuring techniques of transient torsional vibration have been steadily studied by manufacturer of flexible coupling and designer of four stroke marine diesel engine. In this paper, the simulation method of transient torsional vibration for four stroke marine diesel engine application using Newmark method is introduced.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.876-880
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• 2000

Vibration problem of deckhouse structure in a container vessel was investigated through the analysis and measurement. The natural frequency of deckhouse structure was found to be resonant with main engine 4th order excitations in the operating range, major sources of which were main engine inertial moment and axial thrust of the propulsion shafting system. To investigate and solve the problem, exciter test was performed to identify the vibration chracteristics of the ship structure and mechanical balancer was installed to compensate the 4th order inertial moment. Measurement results under the conditions with and without balancer operating were compared and analyzed to confirm the balancer effect. Good coincidence was found between the measurement and analysis results, which made it possible to predict the vibration problem in the earlier design stage.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.2
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• pp.102-111
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• 1995

The non-periodic fluctuation of the engine torque appears to be the major source of the torsional vibration of the automotive driveline. The reduction of this torsional vibration has become a significant problem along with the requirements of higher performance. The torsional vibration of the automotive driveline can be reduced by smoothing the fluctuation by adjusting the torsional characteristics of the clutch-disc. Computer simulation of the driveline is a useful investigative tool on studying the torsional characteristics of the clutch-disc. In this paper, a dynamic model for the automotive driveline was developed, and the engine torque of the model were evaluated with experimental data. By executing a simulation using the model, it has become possible to obtain the clutch-disc torsional characteristics for reducting the torsional vibration at creeping.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.742-748
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• 2003

As for marine propulsion shafting system using 4 stroke diesel engine, it is common to apply reduction gear box between diesel engine and shafting with a view of increasing mechanical efficiency, which inevitably require elastic coupling due to avoid chattering and hammering inside of gear box. In this study, optimum method of rectifying propulsion shafting system in case of 750ton fishing vessel specially in a view of torsional vibration, is theoretically studied. After exchange of diesel engine and gear box, analysis result of torsional vibration get worse and so some countermeasure are needed. The elastic coupling is modified from present block type rubber coupling showing relatively high torsional stiffness to rubber coupling with two series elements directly connected. The vibration measurement using two laser torsion meters was done during sea trial, whose results are compared to those of calculation and verified.

• Journal of Biosystems Engineering
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• v.27 no.4
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• pp.273-282
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• 2002

This study was intended to measure and analyze hand-transmitted vibrations from cultivator in idle and operation modes for three different types of field works. Based on this analysis a time for the white finger syndrome to appear on 10% of the operators was estimated assuming that their daily exposure is 3 hours. The 4 methods to reduce the hand vibration were also proposed and compared with each other. The results of the study were summarized as follows : The highest vibration level was recorded during trenching operation, resulting in a total average vibration of 11.5 m/s$^2$. Followings were 7.6 m/s$^2$ during rotary tillage and 7.0 m/s$^2$ for weeding. When exposed to these levels of vibrations three hours a day, the white finger syndrome is likely to appear in 4 years for trenching, 6.2 years for rotary tillage and 6.8 years for weeding operations. Isolation of hand vibration performed by a rubber pad, anti-vibration gloves, a handle anti-vibration device and engine mounts were respectively 15.7%, 16.5%. 26.1% and 27.0%, resulting in most effective methods of the handle anti-vibration device and engine mounts. A better performance of about 33.9% was achieved when both the handle anti-vibration device and engine mounts were used.