• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1710-1715
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• 2000

Estimation of damping ratio for vibration signals measured on the passenger car's seat is useful for the objective evaluation of impact harshness in car. The vibration signal is a transient signal represented by many coupled modes of suspension system. Wavelet transform automatically decouples these modes in the time-frequency domain. Damping ratios for decoupled modes are obtained by logarithmic treatment for the Wavelet transformed signal. The objective evaluation using Wavelet transform has been well corresponded with subjective evaluation done by skilled engineers.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.560-564
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• 2009

This paper introduces measurement and evaluation of vibration of the ship propulsion machinery (ISO 20283-4). ISO 20283-2 for measurement of structural vibration on ships was finalized last year and ISO 20283-4 was drafted and reviewed by particulate ISO members now. As the importance and core field in ISO 20283-4, the torsional vibration of propulsion system for sea going vessels should be analysed in design stage and it should be confirmed by the its measurement during the sea trial. Criteria for evaluation of torsional loadings are defined by IACS (International Association of Classification Societies) UR M68. In this paper, the author introduced the important and controversial matters during the review of ISO 20283-4.

• 한국소음진동공학회논문집
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• 제11권7호
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• pp.267-274
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• 2001

This paper introduces experimental results related to the vibration ride conditions that a korean male subject experienced in the nationwide railway trains and the express bus. Two types of railway train's Saemaulho and Mugunghwaho. and the express bus were chosen to measure how much the whole-body vibrations on the contact area of the back , hip and feet are exposed to the subject. Measured vibration signals were analysed to assess the rife conditions quantitatively and qualitatively. Analysed results are illustrated to unveil how much typical public transportation system in Korea expose whole-body vibration to passengers. Futhermore, the performance evaluation of their seats were carried out to examine their effectiveness in reducing vibration exposure to passengers.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.1038-1042
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• 2003

In order to evaluate dynamic impedance of a hand-arm system it is necessary to measure the hand-transmitted vibration and the reaction force at the same time while gripping the vibrating handle. In the study a device was developed to measure both the vibration and the force. The device consists of a measurement handle with four strain gauge and two accelerometers and a PC based control system with a program for the signal processing and evaluation of the hand-transmitted vibration and reaction force. The handle was installed on the vibration shaker so that it can move by the generated signal from the control system. As an application of the system dynamic reaction force and the frequency weighted acceleration at the handle attached to the shaker were measured at various grip force and feed force. This system will be very useful in the area of impedance measurement and the evaluation of performance of anti-vibration gloves.

• 한국소음진동공학회논문집
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• 제12권8호
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• pp.626-631
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• 2002

A modified equation for the evaluation of discomfort of a seated human body exposed to differential vibration at the seat and the floor was proposed in this paper. Through the review and analysis of the preceding studies, effect of phase difference between the seat and the floor vibration on discomfort were quantitatively identified. The phase effect was shown to be governed by not only phase difference between the two vibrations but both their frequency and the magnitude, which means the present equation for the evaluation of perceptual amount of vibration provided by ISO 2631-1 should be modified. The proposed equation was developed such that the correction function was multiplied to the present equation. The correction function consisted of three parts, each of them represented the effect by phase difference, frequency and vibration magnitude on discomfort respectively.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1990년도 추계학술대회논문집; 한양대학교, 서울; 24 Nov. 1990
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• pp.107-112
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• 1990

In the vibration analysis of structure in fluid such as ships and offshore structures, the hydrodynamic added mass considerably affects the result of analysis. Therefore correct evaluation of the hydrodynamic added mass effect is required for an accurate analysis. But the correct evaluation of the effect is not simple because the added mass varies with the mode shape of vibration as well as the configuration of the structure. The universal method employed to evaluate added mass in ship hull vibration is Lewis's method via the introduction of 3 dimensional correction factor. But this conventional method is valid only for beam-like vibration.

• 한국소음진동공학회논문집
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• 제21권8호
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• pp.761-767
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• 2011

Free and forced vibration analysis of the global ship structure using the 3-dimensional finite element(FE) method requires not only the specialized knowledge such as ship structure interacted with fluid, damping and various excitations due to propulsion system but also time-consuming manual tasks in FE modeling, analysis and response evaluation. As a result, the quality of the vibration analysis highly depends on engineer's expertise and experience. In this study, a framework system to improve the efficiency of global ship vibration analysis is introduced. The system promising the utilization of MSC/Patran and MSC/Nastran consists of various modules to support data management, FE modeling of ship structure and loading, input deck generation for free and forced vibration analysis, data extraction and evaluation of analysis results, and databases for FE models of marine diesel engines and vibration criteria. The system may be useful for pursuing standardization of uncertain analysis factors as well as reducing time, cost and human dependency in ship vibration analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.779-784
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• 2011

Free and forced vibration analysis of the global ship structure using the 3-dimensional finite element(FE) method requires not only the specialized knowledge such as ship structure interacted with fluid, damping and various excitations due to propulsion system but also time-consuming manual tasks in FE modeling, analysis and response evaluation. As a result, the quality of the vibration analysis highly depends on engineer's expertise and experience. In this study, a framework system to improve the efficiency of global ship vibration analysis is introduced. The system promising the utilization of MSC/Patran and MSC/Nastran consists of various modules to support data management, FE modeling of ship structure and loading, input deck generation for free and forced vibration analysis, data extraction and evaluation of analysis results, and databases for FE models of marine diesel engines and vibration criteria. The system may be useful for pursuing standardization of uncertain analysis factors as well as reducing time, cost and human dependency in ship vibration analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1285-1289
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• 2006

In a large diameter piping system, high frequency energy can produce excessive noise, high vibration, and failures of thermo-well, instrumentation, and attached small-bore piping. High frequency energy is generated by flow induced vibration like vortex shedding in orifices and valves. Once this energy is generated, amplification may occur from acoustical and/or structural resonances, resulting in high amplitude vibration and noise. At low frequencies, pipe vibration occurs laterally along the pipe's length, but at higher frequencies, the pipe shell wall vibrates radially across its cross-section. The simple beam analogy which is based on the beam mode vibration can not be applied to evaluate shell mode vibration. ASME OM3 recommends that the stress be measured directly by strain gauge and be evaluated according to the fatigue curves of the piping material. This Paper discusses the excitation and amplification mechanism relevant to high frequency energy generation in piping system, the monitoring method of the shell mode vibration in ASME OM3, the evaluation method generally used in the industry. Finally this paper presents the stress evaluation of the cavitating venturi down stream piping, where high frequency shell mode vibrations were observed during the operation.

• 한국소음진동공학회논문집
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• 제14권5호
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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.