• Journal of KSNVE
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• v.3 no.3
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• pp.253-257
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• 1993

In this study, vibration analysis of a refrigerator was carried out to reduce vibration induced noise. When the components of a machine are assembled together, the natural frequencies of each component are changed since they have influences on one another. To avoid the problem of resonance, the vibration characteristics of each component must be checked systematically after they are designed. For this purpose, vibration analysis of a refrigerator was done using a component synthesis method. The experimental and analytical results showed good agreement and are presented here.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.945-948
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• 2004

A free vibration analysis of air-operated valve(AOV) is investigated. The vibration characteristics of AOV with size variations are studied. The effects of inner pressure on the natural frequencies are also studied. The analytical results are compared with expermental results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.7
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• pp.619-625
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• 2012

Since the fuel is always exposed to turbulent flow, the grid strap shows flow induced vibration characteristics that impact on the nuclear fuel soundness. The dynamic behavior of grids in nuclear fuels is quite complex, since two pairs of spring and dimple support are contacted with rods by friction in the limited space. This paper focuses on investigation of the grid strap(test fuel strap, TFS) vibration in one cell. TFS consists of a single spring and double dimples. To identify the grid strap vibration, modal analysis of the strap is performed using finite element method(FEM). Modal testing on a $5{\times}5$ grid structure without rods is performed. The modal testing results are compared to analytic results. In addition, random test considering rod effect is performed about a $5{\times}5$ grid with rods under real contact condition in the air. Finally, the strap vibration of a $5{\times}5$ fuel bundle in investigation of flow induced vibration(INFINIT) facility is measured in real fluid velocity condition without heating. It is shown that modal frequencies from the test are almost equal to those peak frequencies in the INFINIT test.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.148-159
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• 2004

This paper discusses vibration mode of the drivesystem considered the vehicle body's dynamic characteristics to study the influence of the vehicle body's dynamic characteristics on the vibration mode of the engine mount system and the ride quality of a vehicle. The simulation model consists of the engine mount system, the powertrain and the rigid or elastic vehicle body. Variables used in this study are the stiffnesses of an engine mount system and the excitation forces. The Goals of the study are analyzing both the vibration transmitted to the vehicle body including the drivesystem and the influence of the vehicle body's dynamic characteristics on the engine mount system. The mode of drivesystems with a rigid and a elastic vehicle body was compared. From the result of the forced vibration analysis for the drivesystem with a elastic vehicle body, it is shown that the vehicle body's dynamic characteristics influence on the engine mount system reciprocally.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.543-548
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• 2006

This paper presents the vibration characteristics of scaffolding structures with a hoist according to payloads. In order to analyze the vibrational and structural characteristics for 20-step scaffolding structure, structural and vibrational characteristics for 2-step scaffolding structure were compared with some experimental results. The numerical results for natural frequencies of scaffolding structures have a good agreement with experimental ones. Through the numerical analysis, firstly, it is shown that the maximum stress of scaffolding structures is lower than von-mises yield criteria when four persons with total weight of 280kgf are working at the top of the scaffolding structures. Secondly vibration characteristics including natural frequencies and modes for scaffolding structures are shown in case of various kinds of moving masses.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.922-924
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• 2014

This paper is concerned with the analysis of natural vibration characteristics of an accelerometer used in power plant. The malfunction of the accelerometer in high-temperature environment may produce erroneous sensor signal and the erroneous signal may cause unpredicted accidents in power plants. Hence, the accelerometer which endures high temperature needs to be developed. In this study, the natural vibration characteristics of the accelerometer were investigated prior to the development of the high-temperature accelerometer. The main mechanical part of the accelerometer is a spiral spring. In this study, the dynamic characteristics of the spiral spring were investigated first by using a commercial finite element code. Numerical results show that the thickness of the spiral spring affects the dynamic characteristics. Numerical investigation on the effect of temperature on the performance of the accelerometer will follow.

• Nuclear Engineering and Technology
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• v.47 no.2
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• pp.165-175
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• 2015

The application of neutron noise analysis (NNA) to the ex-core neutron detector signal for monitoring the vibration characteristics of a reactor core support barrel (CSB) was investigated. Ex-core flux data were generated by using a nonanalog Monte Carlo neutron transport method in a simulated CSB model where the implicit capture and Russian roulette technique were utilized. First and third order beam and shell modes of CSB vibration were modeled based on parallel processing simulation. A NNA module was developed to analyze the ex-core flux data based on its time variation, normalized power spectral density, normalized cross-power spectral density, coherence, and phase differences. The data were then analyzed with a fuzzy logic module to determine the vibration characteristics. The ex-core neutron signal fluctuation was directly proportional to the CSB's vibration observed at 8Hz and15Hzin the beam mode vibration, and at 8Hz in the shell mode vibration. The coherence result between flux pairs was unity at the vibration peak frequencies. A distinct pattern of phase differences was observed for each of the vibration models. The developed fuzzy logic module demonstrated successful recognition of the vibration frequencies, modes, orders, directions, and phase differences within 0.4 ms for the beam and shell mode vibrations.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.857-864
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• 2016

In the present work, vibration analysis of high speed rotary bell cup model for paint atomizer application is carried out through numerical simulation. At first, eight bell cup models, considering four different cup shapes and two different cup diameters, are proposed and corresponding dynamic characteristics are investigated. To evaluate the operating stability, critical speed analysis is conducted using Campbell diagram and separation margin between operating speed and critical speed is identified. Unbalance vibration responses are also studied according to operating speed and balancing quality grade of G. Finally, the stability and adequacy of the proposed bell cup models are discussed for field application.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.8
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• pp.661-667
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• 2004

The characteristics of noise and vibration by a heavy impact source was studied. The triggering method was used for increasing the reliability and stability to measure the level of sound pressure. sound intensity and vibration acceleration. A simple finite element model and a rigid body analysis method were suggested to calculate the natural frequencies of the multi-layer floor system. The results show that the resilient materials decrease the natural frequency of the reinforced concrete slab, make a resonance with dominant driving frequency in the low frequency region, and increase the vibration and noise level. A simple finite element model and rigid body models was suggested to calculate the natural frequencies of the floor systems.

• Special Issue of the Society of Naval Architects of Korea
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• 2013.12a
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• pp.85-89
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• 2013

In the engine room and the aft body, there are so many fluid tanks such as fresh water tank and oil tank. The vibration analysis for the fluid tank structures has to consider the added mass effect due to the fluid. However, it is known that the result of the fluid tank has the difference according to the boundary condition of the fluid field such as infinite fluid and finite fluid. In this paper, a numerical case study is carried out for the research about the vibration characteristics of the fluid tank with various fluid field. In addition, an experimental study is carried out to verify the validity of the vibration analysis for the fluid tank structure.