• 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.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.3
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• pp.1-7
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• 2011

The analysis shows that the vibration is one of the main reasons of turbine failure. Especially, the problems caused by vibration occur right after retrofit of the turbine-generator and restarting the turbine. Through the case study of high vibration caused by after the turbine trip and restart, turbine vibration was identified to be influenced by startup condition. Turbine startup at high casing temperature right after unscheduled turbine trip cause radial expansion in rotor by contraction in axial direction, while casing continues to contract by steam flowing into casing. Consequently, gap between rotor and casing decrease until to metal contact to cause high vibration. Through the case study of high vibration of turbine-generator system after generator retrofit, it was identified that generator replacement could cause high vibration in turbine-generator system if the influence of generator replacement on entire system was not considered properly. To prevent startup delay caused by high vibration, it is important to keep the gaps at the design standard and start the turbine after thermal equilibrium.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1376-1383
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• 2001

Modem technology depends on the reliability of extremely high technology equipments. In the production of semiconductor wafer, optical and electron microscopes, ion-beam, laser device must maintain their alignments within a sub-micrometer. This equipment requires a vibration free environment to provide its proper function. Especially, lithography and inspection devices, which have sub-nanometer class high accuracy and resolution, have come to necessity for producing more improved giga and tera class semiconductor wafers. This high technology equipments require very strict environmental vibration standard, vibration criteria, in proportion to the accuracy of the manufacturing, inspecting devices. The vibration criteria of high sensitive equipment should be represented in the form of 'exactness' and 'accuracy', because this is used as basic data for the design of building structure and structural dynamics of equipment. This paper deals with the properties of time and frequency domain in order to obtain more improved vibration criteria for high sensitive equipment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.776-779
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• 2005

Liquefied Natural Gas takes up six hundredths of the volume of natural gas, which makes storage and transportation much easier. To send out natural gas via a pipeline network across the nation, high pressure LNG pumps supply highly compressed LNG to high-pressure vaporization facilities. The Number of high Pressure LNG pumps determined the send out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high beat vibration at cryogenic pumps, vibration and motor current analysis have been performed. And high beat vibration of cryogenic pumps could be reduced due to the modification of motor rotor.

• Design & Manufacturing
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• v.17 no.4
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• pp.14-23
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• 2023

The electric vehicle market is developing rapidly around the world. Also, parts of electric vehicles require precision.In order to produce high-precision motor cores,Press equipment must also have good precision. Drive motor cores are an important technology for electric vehicles. It uses a large high-speed press to mass-produce drive motor cores. Because it's a large high-speed press, there are many reasons why the precision is not good. One of the causes is vibration and noise. Recently, as environmental demands have become stricter, regulations on noise and vibration have been strengthened. It is important for press machines to reduce vibration first for sound insulation and dust proofing. This is because the "breakthrough" phenomenon occurs in the press. Dynamic precision is the precision under the load of the press, Design considering strain and stiffness shall be made. Vibration and noise may occur due to SPM of high-speed press,And vibration and noise can cause structural deformation of the press. Structural deformation of the press can affect the precision of the product.Noise and vibration also cause problems for workers and work environments. Problems with vibration and noise occur during press processing, and vibration and noise lead to damage to the mold or defects in the product. Reliability in high-quality technology must be secured with low noise and low vibration during press processing. Modular shape and deformation energy effects were analyzed through finite element analysis. In this study, a study on vibration and noise countermeasures was conducted through finite element analysis of a large high-speed press.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.302-307
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• 1998

In the production of semiconductor wafer, optical and electron microscopes, ion-beam, laser device must maintain their alignments within a sub-micrometer. This equipment requires a vibration free environment to provide its proper function. Especially, lithography and inspection devices, which have sub-nanometer class high accuracy and resolution, have come to necessity for producing more improved giga and tera class semiconductor wafers. This high technology equipments require very strict environmental vibration standard, vibration criteria, in proportion to the accuracy of the manufacturing, inspecting devices. The vibration criteria of high sensitive equipment should be represented in the form of exactness and accuracy, because this is used as basic data for the design of building structure and structural dynamics of equipment. The study on the evaluation of the factors affecting the permissible vibration criteria is required to design the efficient isolation system of the semiconductor manufacturing of equipment. This paper deals with the properties of the effected factor for vibration criteria of high sensitive equipment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1290-1295
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• 2006

The 120 meters high pressure feedwater heater drain piping in nuclear power plant had been suffered by excessive vibration from the beginning of power generation. As time goes by, the piping vibration was beyond the allowable limit and an appropriate countermeasure was required to prevent the fatigue failure of the pipeline from the abnormal vibration. In this study, the vibrational characteristics of high pressure feedwater heater drain piping and the countermeasure for abnormal vibration were investigated. Among the several vibration reduction methods, the piping layout changed by making the smooth pipeline was applied to the high Pressure feedwater heater drain piping in nuclear Power plant. Applying the countermeasure, the vibration level was found to reduce over 54 percents and was satisfied under the allowable velocity at the full-power operation condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.109-112
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• 1995

This paper analyzes high efficiency anti-vibration boring bars which increase stability against chatter vibration in boring operations. Structural analysis and mathematical modeling with considering dynamic properties for three types of existing boring bars are performed to search for optimal design parameters. The purpose of this paper is to find out design parameters for high efficiency anti-vibration boring bar.

• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.366-370
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• 2014

Considering a countermeasure against vibration along the existing line, in many cases, it may be the most efficient method to replace existing fasteners with high resilient fasteners because of the restriction of the construction of a new track type. There are many types of high resilient fasteners which are different in price and performance. Therefore it is important to choose the high resilient fastener which has best vibration-proof performance per price. In this study, a prediction method which can exactly evaluate the performance of a fastener in the reduction the ground borne noise in the existing line is presented, which is constructed based on the combination of the measurement and the simulation. A numerical example using the presented method is introduced to evaluate the vibration-proof performance for the solution of the vibration problem in the existing line.