Search | Korea Science

Lee, D.H.;Chung, T.Y.;Kim, Y.C.;Shin, Y.H.
- Transactions of the Korean Society for Noise and Vibration Engineering
- /
- v.20 no.12
- /
- pp.1168-1175
- /
- 2010
Excessive torsional vibrations from marine engine shafting systems can be reduced by using torsional vibration dampers. But in order to be tuned effectively, the dampers should be designed through the optimum design procedure. In this paper, the procedure to get the optimum values of system parameters of spring-viscous dampers using effective modal mass of inertia and stiffness is suggested and the damping is determined by the exact algebra optimization method. The validity of the suggested method is confirmed through the application to a 1800 kW four cycle diesel engine and generator system.
https://doi.org/10.5050/KSNVE.2010.20.12.1168 인용 PDF KSCI

Lee, D.C.
- Transactions of the Korean Society for Noise and Vibration Engineering
- /
- v.13 no.12
- /
- pp.923-929
- /
- 2003
As for the marine propulsion shafting system using 4 stroke diesel engine, it is common to apply a reduction gear box between diesel engine and shafting to increase propulsion efficiency, which requires inevitably a certain elastic coupling to avoid chattering and hammering inside of gear box. In this study, the optimum method of rectifying propulsion shafting system in case of 750 ton fishing vessel is theoretically studied in a view of dynamic characteristics of torsion. After the replacement of diesel engine and gear box, the torsional vibration get worse and so some countermeasures are needed. The elastic coupling is modified from a present rubber coupling of block type having relatively high torsional stiffness to a rubber coupling haying two serially connected elements. Torsional vibration damper was installed at crankshaft free end additionally and moment of inertia of flywheel was adjusted. The dynamic characteristics of shafting system was improved by these modification. The theoretical analysis of torsional vibration are compared to measurement results using two laser torsion meters during the sea trial.
https://doi.org/10.5050/KSNVN.2003.13.12.923 인용 PDF KSCI

Park, Yong-Koo;Kim, Hyun-Su;Lee, Dong-Guen
- Journal of Korean Association for Spatial Structures
- /
- v.12 no.2
- /
- pp.65-72
- /
- 2012
In this stury, control performance of tuned mass damper (TMD) with torsional rigidity for an eccentric structure showing torsional responses is investigated. To this end, an eccentric structure subjected to earthquake excitation is used to evaluate the control performance of torsional TMD by varying installed location and torsional rigidity of TMD, To reduce computational time required for repetitive time history analysis of an example structure having non-proportional damping system due to TMD, an equivalent analytical model is used in this study. Torsional properties of TMD usually neglected in typical TMD are verified to be effective in reduction of torsional responses of the eccentric structure. In the case of eccentric structures, it has been seen that the center of a plane of a structure may not be optimal location of TMD.
https://doi.org/10.9712/KASS.2012.12.2.065 인용 PDF KSCI

Hong, D.P.;Chung, T.J.;Tae, S.H.
- Transactions of the Korean Society of Automotive Engineers
- /
- v.3 no.2
- /
- pp.30-41
- /
- 1995
Gear rattle is a source of vibration and noise in automotive gearbox casing and generally occurs at or near system resonant frequencies. The neutral gear rattle of the gearbox. is affected by the stiffness and hysteresis torque in the clutch disk and drag torque determining balancing point of the clutch disk operating range. The experiment is carried out in the pre-damper type clutch and a manual transmission of a automobile equipped for inline four-sylinder four-cycle 1.5L MPI engine and the computer simulation is executed by 5th order Runge-Kutta method. The results of the simulation analysis and experimental studies show the dynamic behavior of clutch and a phenomenon of the neutral gear rattle with respect to drag torque and torsional characteristics of the clutch.
PDF