• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.351-356
• /
• 1997

With the aid of advanced structural engineering, the construction of infrastructures has been recently accelerating to keep up with rapid economic growth. Construction activities and operation of transportation facilities cause civil petitions associated with vibration-induced damages or nuisances. As part of the decrease of vibration induced damage, the objective of this study is to develop vibration-controlled concrete with vibration-reduced materials, which can be recycled from obsolete materials, such as aged tires, plastics and etc. Appropriate mix proportion has been used for making 10 reinforced concrete panels with vibration-reduced materials, which have been tested to investigate on vibration reduction capability, based on the time and frequency domain analysis, and vibration velocity level analysis. Vibration-reduced mixtures are latex, styrofoam, rubber powder and plastic resin, which have been determined to by reduce vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.449-452
• /
• 2005

This paper introduces a study for the noise reduction of a range hood for household. Generally, range hoods have a built-in sirocco fan from which squawky noises are generated. Though the squawky noises have low noise level, these kinds of noises make most of the users nervous. For the purpose of noise reduction, in this study, a perforated plate system is installed in the fan housing of range hood. From the experimental results, it is confirmed that the noise level omitted front the range hood is decreased above 2dB(A) in all frequency regions due to the effect of noise reduction by perforated panel system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.1205-1208
• /
• 2006

This paper introduces a study for the noise reduction of a range hood for household. Generally, range hoods have a built-in sirocco fan from which rumbling noise is generated. Though the rumbling noise has low noise level. this noise makes most of the users nervous due to the its low frequency characteristics. For the purpose of noise reduction, in this study, a micro-perforated panel system is installed in the fan housing of range hood. From the experimental results, it is confirmed that the noise level emitted from the range hood is decreased over 2dB(A) in all frequency regions due to the effect of noise reduction by micro-perforated panel system.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.8
• /
• pp.886-895
• /
• 2008

Resilient materials are generally used for the floating floors to reduce the floor impact sound. Dynamic stiffness of resilient material have a close relation with the floor impact sound reduction. In this study, to examine the relationship between dynamic stiffness and lightweight impact sound level, the dynamic stiffness and floor impact sound level of 51 resilient materials were measured. The impact sound level of each of these resilient materials, whose dynamic stiffness was measured, was measured before and after installation, and the level difference (${\Delta}L$) was analyzed. The result of test showed that the dynamic stiffness of resilient materials decreased, the lightweight impact sound level also decreased, and there was a correlation between the dynamic stiffness and the lightweight impact sound, especially in the low frequency domain.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.1020-1023
• /
• 2004

Recently, Cooling tower are used the necessary element in a residential area and living space on the viewpoint of indoor temperature control. The purpose of this study is to assistance the comfortable environment and economical measures of noise transmission mechanism on tile cooling tower. The results show that noise evaluation interact the main factor of distance reduction and diffraction reduction. Noise criterion apply to the NC level and equivalent transmission loss about already the design of noise reduction.

• Journal of the Society of Naval Architects of Korea
• /
• v.42 no.3
• /
• pp.249-258
• /
• 2005

Recently, the vibration reduction at a local structure such as compass deck has been continuously requested by ship owner and shipbuilder. Because crews are afflicted with vibration, severe vibration problems even bring about a damage of structure. This study conducted to get an optimized stiffener size of compass deck to reduce the vibration level and decrease the weight of structure in ship. NASTRAN external call type optimization software (OptShip) which makes use of NASTRAN as a solver is used as an optimization tool. The results indicate that the optimum design is promising for real applications.

• Journal of Ocean Engineering and Technology
• /
• v.33 no.2
• /
• pp.196-202
• /
• 2019

In this study, the excessive noise and vibration phenomena of a high-speed Ro/Ro passenger ship were analyzed, and a countermeasure was taken based on them. This ship was granted a comfort class notation by the classification society, which was COMFORT-VIBRATION-II and COMFORT-NOISE-CREW-II. However, unfortunately, excessive noise and vibration in the aft part of the ship were delivered from the twin shaft propellers, and therefore the Class Requirement was not satisfied before delivery. In order to obtain the class notation, all of the concerned parties came to an agreement to reduce the noise and vibration level during operation after delivery because a seasonal ferry service was already scheduled and the cabin was fully booked. The root cause of the massive amount of noise and vibration was mainly the propeller-induced excitation pulse and beating that occurred from the mismatch of the rotating speeds of the two shaft lines. A 1st order vibrating force and beating phenomena existed in the propeller. Thus, a reduction of the excitation force, elimination of the beating phenomena, and decrease of the noise level at the aft area cabins and public spaces were required. In addition, structural reinforcements were conducted using pillars and additional girders at the aft part of the decks.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.05a
• /
• pp.1157-1161
• /
• 2007

A construction noise is the main reason for people's petition among the pollution. The purpose of this study is to develop the noise prediction program to see the level of the noise on the construction site more accurately. For this purpose, the database of the power level on the various equipments was made. The noise reduction by distance and the noise reduction by diffraction of barrier were mainly considered and calculated. The simple noise prediction program will provide the information about proper height and length of the potable barrier which satisfies noise criteria of the construction sites from a construction planning stage. To investigate the reliability of this program, the predicted data was compared with the measured data. An average of difference between measured data and predicted data is 1.3 dB(A) and a coefficient of correlation is about 0.95.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.949-954
• /
• 2000

In terms of vibration damage and the serviceability for occupants in buildings, the purpose of vibration study lies in the reduction of vibration damage. However, only when vibration level of buildings is available, measures of vibration control and base isolation can be taken. The purpose of this paper is to provide a fundamental analysis method to estimate structural vibration. After analysing by using two methods, infinite model, combination method, a comparison between analysed results and the results of previous studies was performed to prove the validity of the prediction on the vibration of building structure. Thus, if the material property of soil and quantity of load sources are known before construction being started, the vibration level could be predicted by using these methods.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.738-742
• /
• 2005

Ground vibration at Gil-dong in Seoul induced by the 5th ling of Seoul Subway is predicted using various prediction methods and compared with measured vibration. Also, several issues on the improvement of prediction methods are discussed. Furthermore, as an alternative vibration source, measured vibration acceleration level(VAL) on the tunnel wall of the Bundang line of Seoul Subway is applied to the prediction of the VAL at the location mentioned previously. Then requirements accompanied to the suggestion of the new vibration source appropriate to the condition of Seoul Subway.