• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.169-176
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• 1998

This paper presents the vibration characteristics of a motorcycle body frame. In order to study the excitation mechanism. for example, of handle vibration, discrete models and finite element model are developed for the calculation of natural frequencies and mode shapes of the driveline and body. which can lead to the resonances. Experiments are also conducted to compare with the analytical results From the various kinds of vibration reduction methods, the technical realizable one is presented to reduce the handle vibration responses at the start of driving.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.796-799
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• 2005

In 2005, a regulation on the heavy-weight impact sound was released, which restricted concrete slab thickness of standard floor to 210mm. To reduce heavy-weight impact sound, damping materials and structural reinforcement system have been proposed. In this study, the effect of compressive strength on the heavy-weight impact vibration and sound were investigated. FEM analysis was conducted for the 34PY apartment with different concrete strength (210, 350, 420kg/cm$^2$). In addition, apartment floors with different concrete strength were constructed and the floor impact vibration and sound were measured. Results of FEM analysis and measurement show that the resonance frequency of concrete slab was increased by the increment of concrete strength. However, floor impact sound pressure level did not decrease because the nor impact vibration and sound pressure level in 63Hz band increased.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.385.2-385
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• 2002

Hermetic rotary compressor is one of the most important components for air conditioning system since it has a great effect on both the performance and the noise and vibration of the system. Noise and vibration of rotary compressor is occurred due to gas pulsation during compression process and unbalanced dynamic force. In order to reduce noise and vibration, it is necessary to identify sources of noise and vibration and effectively control them. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.381-386
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• 2002

This paper presents a piezoelectric shunt methodology to reduce unwanted vibration of optical disk drive(O.D.D.). After briefly investigating a second-order mechanical vibration absorber model, the O.D.D. structure is incorporated with the piezoelectric shunt circuit. In order to evaluate feasibility of multi-mode passive damping of the structure, admittance measurement of piezoceramic is undertaken. The parameters are optimally tuned by admittance measurement results on the basis of the circuit model and displacement transmissibility is evaluated. To verify validity of admittance measurement result, experiment is performed and vibration reduction is achieved at two different modes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.483-488
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• 2008

The exhaust system, including a muffler, is one of the major sources to generate the radiated noise of construction equipment. In general, the muffler is applied to construction equipment in order to reduce the exhaust noise. Sometimes, however, the higher exhaust noise can be experienced due to the flow effect inside a muffler. So, it is required to consider the flow effect to reduce the exhaust noise level of construction equipment. In this paper, various tests were performed to calculate the flow noise effect inside a muffler. Through a series of tests with respect to a variety of design parameters, a new design program for low noise muffler was developed and applied to reduce the exhaust noise of the construction equipments. These results make it possible to understand the dynamic characteristics of the flow noise and to design the low noise muffler for the construction equipments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.560-564
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• 2007

In order to reduce the level of recoil force, new recoil technology must be employed. The present study discusses a soft-recoil mechanism that can reduce dramatically the recoil force. The dynamics of the soft-recoil system with hydraulic dampers are described and simulated. The results of the simulation show that FOOB system can reduce the recoil force and the recoil stroke compared to conventional systems. However, the FOOB system is not able to perform well when the fault modes happen. Hence, this study uses the MR damper to achieving FOOB under fault modes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.862-867
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• 2000

The auxiliary engine exhaust noise in ships are directly transmitted to bridge wing with the only distance attenuation. It is not so practical that no special treatment can be applied between exhaust pipe and bridge wing in order to reduce the transmission of the exhaust noise. In general, a silencer is fitted to reduce the exhaust noise and also noise of bridge wing. The silencer should be properly designed under the consideration of the frequency component of the exhaust noise and the required insertion loss. In this paper, the frequency component of exhaust noise of various engines are compared and a design and a design and installation of silencer to reduce low frequency is introduced.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.177-182
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• 2000

This study aims to provide an effective method to reduce construction noise generated by breakers. To reduce the breaker's noise level, a sound encloser was developed; the sound insulation's performance was tested in the field. From the field test, the following results were obtained. The sound insertion loss was about 6.5dB(A), even though part of the sound encloser for the breaker was left unclosed. This is equal to the reduction value which can be obtained by using more expensive low noise breakers, proving that there are more effective measures for sound insulation at lower cost. The characteristic of frequency was evaluated to show an even reduction through all frequency bands, except 630Hz.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.911-916
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• 2002

One of important roles of concrete track is to reduce vibration transmitting to subgrade. In this paper, a numerical method for evaluating the effects of vibration reduction of concrete track is presented. Using the method, high frequency dynamic analyses and track-tunnel-soil interaction analyses are carried out for three types of concrete track in order to investigate the vibration reduction effects compared with normal ballast track.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.107-117
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• 2002

The blast works for open cuts and underground constructions near urban areas have recently increased complaint of ground vibration, air blast and fly rock. In order to reduce these problems, it is necessary to develop more cautious blasting, or non-blast excavation methods by mechanical power. For these breaker workings instead of blast are sometimes adopted. To compare the characteristics of blast vibration with breaker vibration, the level, range of frequency and spectrum amplifications of each vibration were studied.