• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.10a
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• pp.167-172
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• 1996

A Dual Mass Flywheel system is a evolution to the reduction of torsional vibration and impact noise occuring in powertrain when a vehicle is eit-her moving or idling. The name already explains what it is : The mass of the conventional single mass flywheel is divided. One section continues to belong to the mass moment of inertia of the engine-side. The ot-her section increass the mass moment of inertia of the transmission-side. The two masses are connected via a spring /damping system. This reduces the speed at which the dreaded resonance occurs to below idle speed. Since 1984 Dual Mass Flywheel has been de-veloped again and again. But the prosidures of de-velopment of D.M.F system didn't have had differe-nce from conventional clutch system's trial and err-or This paper presents the method for systematical design of D.M.F system with demensionless design variables of D.M.F system mass ratio between two flywheels λ. natual frequency rate of two flywheel s, ${\gamma}$and viscosity coefficient ζ. And experimental re-sults are used to prove these theoretical results.

• Journal of KSNVE
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• v.6 no.6
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• pp.851-856
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• 1996

The active noise cancellation system showing the effective convergence and stability has been studied by simplifying the controller structures using the weighting factors of control error path to the multi-channel filtered-x LMS algorithm which needs a lot of calculations and the performance has been verified experimentally. Besides, to implement the system performance in a vehicle cabin, experimental work for selecting the suitable numbers and positions of the microphones and speakers was accomplished. Effectively combining a TMS 320C 31 main processor conducting real number calculations and having various functions with other components, the purpose-built system board for active noise cancellation has been designed and with this board, car active noise cancellation system showing maximum stable 10dB noise reduction has been obtained at the car idling conditions above 3000rpm range.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.171-176
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• 2003

A Test Facility was established to carry out the integrated propulsion performance tests(IPPT). To perform IPPT's with maximum safety, an emergency blockage system was investigated. An emergency blockage system using combustion chamber pressure and acceleration signals was set up to monitor ignition delay and fail, flame out, propellant feeding status, unstable combustion and excessive structural vibration. With such system, the maximum safety could be secured by rapid judgement and follow-up measures, which made IPPT's be safely completed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.17-23
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• 2017

This study is about the development and revision of a blower design for a ventilation system. In this study, to describe the flow in the 4000CMM grade blower, 3-dimensional steady-state turbulence was assumed to govern the flow equation. The flow field with velocity distribution according to the elbow duct of the ventilation system is also compared. Finally, vibration was observed in the blower at the installation to ventilation system. The cause was due to a problem in the manufacturing process of the airfoil type impeller.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1151-1156
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• 2003

The dynamic properties of short-fiber reinforced Chloroprene rubber for vibration isolators have been studied as functions of interphase conditions and fiber content. The loss factor showed the maximum at strain amplitude 2%, and increased 0.09 for matrix, 0.05 for reinforced rubber with increasing frequency respectively. The dynamic ratio rapidly decreased with increasing strain amplitude, and some increased with increasing frequency. The better interphase condition showed the lower dynamic ratio. Therefore, the short-fiber reinforced rubber could have the better isolation in frequency ratio(${\sqrt{2}}min$.) compared to frequency ratio(${\sqrt{2}}max$.). And we have investigate the possibility of applying short-fiber reinforced rubber to automotive engine mount.

• International Journal of Fluid Machinery and Systems
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• v.10 no.3
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• pp.307-317
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• 2017

In liquid-propellant rockets, POGO instability can occur, in which a fluctuation of propellant supply to the engine, a thrust fluctuation, and a structural vibration are coupled. For the prediction of this instability, it is required to provide dynamic characteristics of the pump represented as the transfer matrix correlating the upstream and downstream pressure and flow rate fluctuations. In the present study, the flow rate fluctuation is evaluated from the fluctuation of pressure difference at the different locations assuming that the fluctuation is caused by the inertia of the flow rate fluctuation. The experiments were performed in some flow conditions, and it was shown that the tendencies of dynamic characteristics are related to excitation frequencies, cavitation numbers and flow rate coefficients.

• Journal of Biosystems Engineering
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• v.22 no.4
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• pp.421-432
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• 1997

This study was conducted to investigate dynamic characteristics of agricultural tractor with a particular interest in ride vibrations when it is subjected to various excitation forces. As the first part of it this paper describes development of dynamic model of a tractor-trailer system and its equations of motions. An 3 dimensional 16-degree-of-freedom dynamic model for a tractor-trailer system was developed and its equations of motions were derived, which will be used to investigate the effects of irregular ground surface and excitation forces due to the engine mounted on the tractor. And the excitation forces were also formulated analytically. The transition matrix method and QR algorithm were proposed for numerical solution of the equation of motions fur the developed model. The later parts of the study will include a proof of the model and optimization from which tractors can be designed to minimize the ride vibrations. This will be presented in the second and third papers to be followed shortly.

• Tribology and Lubricants
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• v.25 no.4
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• pp.265-269
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• 2009

The wear of the contact in the tappet accounts for the greatest portion of entire friction loss of an engine, leading to the occurrence of abnormal wear. The coated specimens for earn-tappet wear test were producted by using PVD-Sputtering coating method. It examined the friction characteristics occurring between the earn and the tappet by using the dedicated wear tester and found that the friction torque value was reduced through comparison testing with the existing part when the low friction coating was applied. So application of the low friction coating to actual vehicles will reduce the fuel economy and occurrence of noise-vibration.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.3
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• pp.40-49
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• 1996

With the advance of the standard of living, the demand on automobile goes beyond the simple transportion equipment, therefore the interior noise reduction has been the important factor for improvement of the ride quality. Idling noise is a major vehicle characteristic determining occupant comfort. In the present research two approaches for noise source identification based on theory for multi-input system have been investigated. The concept of the frequency response function and the multi-dimensional spectral analysis were used to estimated the spectra of the noise source.

• Tribology and Lubricants
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• v.18 no.2
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• pp.117-126
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• 2002

Abstract - An integrated condition monitoring algorithm based on an expert system was implemented in this work in order to monitor effectively the machine conditions. The knowledge base was consisted of numeric data which meant the posterior probability of each measurement parameter for the representative machine failures. Also the inference engine was constructed as a series of statistical process, where the probable machine fault was inferred by a mapping technology of pattern recognition. The proposed algorithm was, through the user interface, applied for an air compressor system where the temperature, vibration and wear properties were measured simultaneously. The result of the case study was found fairly satisfactory in the diagnosis of the machine condition since the predicted result was well correlated to the machine fault occurred.