• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.1
• /
• pp.45-50
• /
• 2010

In the refrigerator, the two-phase refrigerant-induced noise of the capillary tube in an evaporator-inlet pipe has been a great concern. The capillary tube is usually covered with insulation-foam packed in the space between inner and outer cabinets without any vibration isolation. Therefore, the refrigerant-induced vibration of the capillary tube can be easily transferred to the outer cabinet, which may increase the radiated noise. In this paper, the characteristics of transferred vibration through the insulation-foam are investigated experimentally by using the refrigerantsupplying equipment. The frequency characteristics, such as dynamic Young's modulus and loss factor, of the insulation-foam are also discussed.

• Journal of KSNVE
• /
• v.9 no.4
• /
• pp.693-702
• /
• 1999

We study the characteristics of airflow and sound noise induced by disk rotation in optical disk drives. The characteristics of airflow around a rotating disk surrounded by various tray structures are numerically investigated using a commercial CFD program and then compared with experimental results. Sound pressure and intensity caused by the fluid-structure interactions in the CD/DVD-ROM drive are measured, and the effect of the ariflow on the sound noise and disk vibration is discussed. In order to reduce airflow-induced noise and vibration around the rotating disk, tray geometry is modified. Both numerical and experimental studies implemented with different tray models show that the improved tray model alters the characteristics of the disk-induced airflow, causing the reduction of the airflow-induced sound level.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.27 no.1
• /
• pp.5-13
• /
• 2017

Noise complaints among neighbors in apartment building are mainly caused by floor impact noise that is structure born noise due to occupant induced floor vibration. To control this noise problems many researchers have investigated floor systems and finishing materials. Light-weight impact noise affects by finishing materials, but heavy-weight impact noise induced by heel impacts during normal walking or jumping of children is concerned with structural system and floor vibration. To figure out the characteristics of floor impact noise and transmission of floor vibration due to human activities, vibration tests were conducted in apartment buildings. Impact hammer, heel drop and walking activities were loaded at center of upstairs living room, and accelerations of slabs for both upstairs and downstairs and sound pressure levels for downstairs were measured. The acceleration ratio of transmitted floor vibration to downstairs and human induced vibration in upstairs was between 0.5 and 1.0 according to slab size, wall, and load type. And floor impact noise occurred in the range of natural frequency of slab.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.10
• /
• pp.763-769
• /
• 2014

This study is on the experiment and prediction of the pipe noise due to the internal fluid. The vibration of pipe external surface and noise in air were measured according to the internal fluid velocity and pipe type. In the experiment, the vibration and noise level of the straight pipe and rounded pipes show that the vibration and noise level are almost same. The 900 mitred pipe shows the high vibration and noise level. In the prediction of noise due to the internal flow, the method using the pipe surface vibration and radiation efficiency shows good agreement with experimental result.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.04a
• /
• pp.609-614
• /
• 2014

This study is on the experiment of the pipe noise due to the internal fluid. The straight pipe, the $90^{\circ}$ mitred pipe, rounded $90^{\circ}$ and $1350^{\circ}$ pipe were tested and measured the vibration and noise. In the experiment, the vibration and noise level of the straight pipe and rounded pipes show that the vibration and noise level are almost same. The $90^{\circ}$ mitred pipe shows the high vibration and noise level. In the prediction of noise due to the internal flow, the use of pipe surface vibration and radiation efficiency shows good agreement with experiment result.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.421-426
• /
• 2005

For the air-conditioner, refrigerant induced noise and vibration should be the problem when it reduced airflow rate in order to reduce the noise at low mode. With the test, it could be verified that one of the main reason for refrigerant induced noise were the velocity and flowing induced force of the refrigerant at the inlet of evaporator. So in order to reduce this velocity with same mass flow rate of refrigerant, quality at the evaporator inlet should be minimized. And in order to reduce flowing induced force of the refrigerant, flowing direction change should be eliminated. So in this paper, it would like to review the characteristics of refrigerating cycle at first and find how the quality and flowing induced force can be minimized.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.1287-1292
• /
• 2001

Subway train-induced ground-borne vibration is studied. Previously used vibration level prediction equations are reviewed. Measured vibration levels are compared with the predicted results and numerically computed results. The results show that vibration level does not decrease proportionally with the distance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.04a
• /
• pp.201-204
• /
• 2014

Recent year, the vibration induced fatigue and noise of piping work become critical in offshore hydrocarbon production facilities with increasing requests by major oil company. In this paper, the risk base piping vibration induced fatigue assessment of NORSOK L-002 standard and UK Energy Institute guideline have been introduced with real project application practice. Also the piping breakout noise evaluation by flow restriction devices of compressible and in-compressible flow are reviewed with its practical application on real project.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11a
• /
• pp.79-84
• /
• 2001

The motivation behind this work is to understand the phenomenon of friction-induced vibration and squeal due to misalignment. In present paper, it is studied on effect of misalignment between friction-induced vibration and squeal by an experiment using a pin-on-disk type experimental apparatus. In order to build an analytical model of the friction-induced vibration system with misalignment, the system is modeled as a single-DOF and 3-DOF system. The results show that the single DOF system can only show stick／slip phenomenon, but the 3-DOF system can show squeal due to misalignment. Consequently, it can be said that the misalignment in a friction-induced vibration system is a source of squeal noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.56-59
• /
• 2003

As the slab is longer and lighter, it is more sensitive to the external force so that the vibration of slab and noise induced by the slab vibration is bigger than expected in normal slab. The purpose of this study is to investigate how the dynamic characteristic of slab is different from the normal slab through the system identification and tn evaluate the vibration control performance when the damper system is installed. Finally, we was trying to understand by what mechanism the slab noise is induced from the slab vibration. The relationship between the vibration and the noise of slab is shown by the numerical simulation.