• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.5
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• pp.363-369
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• 2004

Vibration/noise analysis as well as strength of gear teeth, roller bearing life. joural bearing design are considered in order to develop the high-speed machine centrifugal pump which had a speed increaser. A Campbell diagram, in which the excitation sources caused by the mass unbalance of the rotors and the transmitted errors of the gearing are considered. shows that. at the operating speed. there are not the critical speed. A high-speed machine centrifugal pump was made in order to evaluate developed speed increaser. Also, strict API standard were introduced for reliability evaluation of developed speed increaser, and performance evaluation were carried out. The result that evaluation items about bearing vibration, shaft vibration, noise, and lubrication temperature were selected, and were tested. a high-speed machine centrifugal pump were able to know what were satisfied with API standard all.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.561-566
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• 2008

Recently, because of development of the high speed train technology, the vibration loads by train is significantly increased ever than before. This buried gas pipelines are exposed to both repeated impact loads, and, moreover, they have been influencing by vibration loads than pipeline which is not located under vehicle loads. The vibration characteristic of pipeline is examined by dynamic analysis, and variable is only train speed. Since an effect of magnitude of vibration loads is more critical than cover depth, as increasing the train speed, the vibration speed of buried pipelines is also increased. The slope of vibration velocity is changed by attenuation of wave, at train speed, 300 km/h. From the analysis results, the vibration velocity of pipelines is satisfied with the vibration velocity criteria which are established by Korea Gas Corporation. The results present operation condition of pipelines under rail loads has fully sound integrity based on KOGAS specification.

• Journal of KSNVE
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• v.11 no.2
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• pp.354-364
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• 2001

The vibration induced by high speed train running on rail is dealt with as an environmental problem. The train induced vibration is characterized by moving loads at specific frequencies and soil conditions. In fact, it is predicted that the vibration sources are involved the wheel distance, number of cars, speed of operation, drift of rails, structural born vibration, etc. In this paper the characteristics of transferring vibration induced by the high-speed train in operation is discussed. Field measurements was conducted at region from Chungnam Yungj So-jung-myan to Chungbuk Chungwon hyun-do-myun. In the near future. these data will be used as the fundamental data for establishment of the countermeasure for vibrational reduction of high speed train using the results of the field measurements and quantitative prediction of the vibration level

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.1056-1061
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• 2004

The vibration of rotor systems is caused by various factors, such as misalignment, unbalance, gear meshing, error of assembly, etc. Modal test and TDA/ODS analysis were done. The dynamic analysis of the armature was done with SAMCEF which is a commercial software for finite element and kinematic analysis. The transient response of the armature is calculated by the SAMCEF with the consideration of magnetic force and bearing stiffness, which are the essential elements for the design of high speed cutter. Main frequency of the vibration is due to the unbalance of the armature. The FEM analysis model considering unbalance and the high speed cutter have same vibration properties. The vibration sources of the high speed cutter is proved to be unbalance.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.2
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• pp.113-121
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• 1994

Since two oil shocks in 1970s, all of engine makers have persevered in their efforts to reduce specific fuel consumption and to increase engine power rate as much as possible in marine diesel engines. As a result, the maximum pressure in cylinders of these engines has been continuously increased. It causes direct axial vibration. The axial stiffness of crank shaft is low compared to old types of engine models by increasing the stroke/bore ratio and its major critical speed might occur within engine operation range. An axial damper, therefore, needs to be installed in order to reduce the axial vibration amplitude of the crankshaft. Usually the main critical speed of axial vibration for the propulsion shafting system with a 4-8 cylinder engine exists near the maximum continuous revolution(MCR). In this case, when the damping coefficient of the damper is increased within the allowance of the structural strength, its stiffness coefficient is also increased. Therefore, the main critical speed of axial vibration can be moved beyond the MCR. It has the same function as a conventional detuner. However, in the case of a 9-12 cylinder engine, the main critical speed of axial vibration for the propulsion shafting system exists below the MCR and thus the critical speed cannot be moved beyond the MCR by using an axial damper. In this case, the damping coefficient of an axial damper should be adjusted by considering the range of engine revolution, the location and vibration amplitude of the critical speed, the fore and aft vibration of the hull super structure. It needs to clarify the dynamic characteristics of the axial vibration damper to control the axial vibration appropriately. Therefore authors suggest the calculation method to analyse the dynamic characteristics of axial vibration damper. To confirm the calculation method proposed in this paper, it is applied to the propulsion shafting system of the actual ships and satisfactory results are obtained.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.694-699
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• 2005

This paper deals with a control technique of eliminating the transient vibration of a geared mechanical system. This technique is based on a model-based control with a rotational speed sensor in order to establish the damping effect at the driven machine part. A rotational speed sensor is installed in a driven gear, namely a bull gear. A control model is composed of a reduced-order mechanical part expressed as a transfer function between the rotational speed of the motor and that of the bull gear. This control model estimates a load speed after the rotational speed of the bull gear is acted on the transfer function. The difference between the estimated load speed and the motor speed is calculated dynamically and it is added to the velocity command to suppress the transient vibration generated at the load. This control technique is applied to a dies driving spindle of a form rolling machine. In this paper, the performance of this control method is examined by simulations. The settling time of the residual vibration generated at the loading inertia can be shortened down to about 1/2 of the uncompensated vibration level.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.657-662
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• 2004

This paper presented is a case study of a real compressor rotor of a refinery plant for high speed balancing of flexible rotor. The rotor was tested in the expert high-speed balancing facility established by KIMM at early 2004. The capability of the facility can reach 40000rpm in rotation speed and 8 ton in rotor weight for high-speed balancing. The facility performs multi-plane at-speed balancing using influence coefficient from the vibration data measured at two pedestals. The test rotor had exceeded permissible criteria of vibration at initial run. But by processing a low-speed balancing at 1000 rpm and six trial run trying to calculate influence coefficient of rotor to the range of operating speed, the final result of high-speed balancing revealed a remarkable reduce of vibration at pedestal of the rotor.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.477-485
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• 2007

When Korean High Speed Train (KTX) runs over a high-speed railway bridge, the high-speed railway bridge gives quite large acceleration response. Local vibration at the large cross section, the impact from equally spaced sleepers, the vibration due to elastomeric bearings, and the vibration from the train itself are the causes of this acceleration response. Maximum peaks of the accelerations measured at the bridges are sometimes going over the limit value. Although it is smaller than 0.35G, the limit from the Korean Bridge Design Manual(BRDM), this acceleration response should be reduced for the safety of running trains with high speed. In this paper, to reduce the acceleration response by controlling excessive local vibration at the large cross section, vibration reduction method is studied. The result shows that the effect of elastomeric bearings on the vibration of the bridge is very large and that the vibration reduction device is effective against wing mode local vibration PSC box girder bridge for the high-speed railway, which usually has very large cross section, although it has little effect on global vibration modes such as flexural and twisting modes. The test of the vibration reduction device on the bridge in service has been performed in this study.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.1227-1231
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• 2001

To provide faster service and to relief the road traffic jam, the increase of service speed of conventional railway has been intensively considered. In this study, we measured and analyzed the vibration ride comfort of Saemaeul Train to evaluate the feasibility of 5km/h speed-up in curves and l0km/h speed-up on straight tracks. Four main lines, such as Honam, Kyungboo, ]anghang, Kyungjeon were chosen as representative lines for speed-up feasibility study. The increase of mean ride comfort index in case of speed-up is 0.5-2㏈. The mean ride comfort index of vertical direction in case of speed-up is 107 ∼110 ㏈ for Honam line, 104 ∼112 ㏈ for Kyungboo line, 108∼112 ㏈ for Janghang line and 105∼108 ㏈ for Kyungjeon line. Through this study, we found that the Saemaul Express has slight margin to increase the service speed from the view point of vibration ride comfort.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1435-1440
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• 2008

High-speed train under development is a type of EMU(electric multiple units). Since power sources like motors and gears are distributed in the high-speed EMU, the high-speed EMU generates vibration and sound more than the articulated high-speed train. Vibration of vehicle, vibration between rails and wheels, hunting of bogie and snake motion reduce ride comfort. In this paper, to decrease the vibration of the articulated high-speed train, improvements were presented using an analytical model and a simulation model. The simulation model of the high-speed EMU was designed on the basis of the korean high-speed train and the design parameters for ride comfort were showed and the dynamic characteristics of the vehicle was understood. To consider the characteristics of the vehicle suspension, the analytical model was designed and the simulation model was verified with it.