• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1132-1137
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• 2001

The smart foam that is first proposed by Fuller(2) is not applicable to active noise control in a duct having flow. Thus. this paper presents the ring-type smart foam as an alternative. The ring-type smart foam consists of polyurethane acoustic foam of lining shape and PVDF film embedded along the mid-surface of the foam lining. A feedforward adaptive filtered-x LMS controller is used to minimize the signal from the error microphone. To enlarge quiet sound region. two error microphones are used to update system modeling filter (SIMO method). Sound intensity control using the ring-type smart foam is also discussed

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.5
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• pp.414-422
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• 2013

As structure-borne sound, the floor impact sound is one of the serious noises in residential building. Most of heating system applied to the typical Korean residential building is floor heating system which is called ondol. The ondol usually consists of finishing material, mortar with heating coil, light-weight aerated concrete and reinforced concrete. This study focused on the isolation of heavy-weight impact sound and modification of mortar and light-weight aerated concrete. Specifically the glass foam aggregate was added on light-weight aerated concrete. Also, water-cement ratio and amount of cement on mortar were revised. The sound pressure level of heavy-weight impact was measured in reverberation chamber using both bang-machine and impact ball. The size of specimen was 1 m by 1 m. Substitution ratio of glass foam aggregate on light-weight aerated concrete shows relationship with heavy-weight impact sound pressure level. In addition, heavy-weight impact sound pressure level was decreased with increment of water-cement ratio and amount of cement on mortar.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.582-585
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• 2012

The aluminum extruded panel used for a high speed train shows the largest contribution to sound insulation performance of the train body. However, comparing with the flat panel having the same weight, the transmission loss falls sharply in the local resonance frequency band. Such fall of transmission loss can be improved by increasing the damping of local resonance. This study examines the charging effect of an urethane foam on the aluminum extruded panel of a high speed train. We charged the urethane foam with different mass density and in different way in the core part of the extruded panel. We measure the transmission loss and compare the sound insulation performance according to the density and charging method. Finally, Improvement effect of the transmission loss is compared and analysed in aspect of weight increment.

• Macromolecular Research
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• v.15 no.5
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• pp.443-448
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• 2007

To improve the sound damping effect of flexible polyurethane foam, with an open-cell structure, various plate-like fillers, such as bentonite, organophilic clay and sodium montmorillonite intercalated with poly(ethylene glycol), were incorporated for the creation of nanocomposites. The plate-like fillers effectively improved the sound damping within the high frequency range. The structures of the nanocomposites and foam were examined using X-ray diffraction and scanning electron microscopy. The mechanical properties and flammability of the foams were also examined.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1145-1148
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• 2007

Resilient materials are generally used for the floating floors to reduce the floor impact sound. Dynamic stiffness of resilient material, which has the most to do with the floor impact sound reduction. The resilient materials available in Korea include EPS (Styrofoam), recycled urethane types, EVA (Ethylene Vinylacetate) foam rubber, foam PE (Polyethylene), glass fiber & rock wool, recycled tire, foam polypropylene, compressed polyester, and other synthetic materials. In this study, we tested floor impact sound reduction characteristic to a lot of kinds of resilient material. The result of test showed that the amount of the heavy-weight impact sound reduction appeared by being influenced from this dynamic stiffness of resilient material. The dynamic stiffness looked like between other resilient materials, a similar to the amount of the heavy-weight impact sound reduction was shown.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.830-834
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• 2008

Resilient materials are generally used for the floating floors to reduce the floor impact sound. Dynamic stiffness of resilient material, which has the most to do with the floor impact sound reduction. The resilient materials available in Korea include EPS (Styrofoam), recycled urethane types, EVA (Ethylene Vinylacetate) foam rubber, foam PE (Polyethylene), glass fiber & rock wool, recycled tire, foam polypropylene, compressed polyester, and other synthetic materials. In this study, we tested floor impact sound reduction characteristic to a lot of kinds of resilient material. The result of test showed that the amount of the Light-weight impact sound reduction appeared by being influenced from this dynamic stiffness of resilient material. As the decreasing dynamic stiffness of resilient material, the impact sound reduction amount is increased, especially in the low frequency domain.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1262-1269
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• 2008

Though multilayered foam-panel structures have been widely used to reduce sound transmission in various fields, most of the previous works to design them were conducted by repeated analyses or experiments based on initially given configurations or sequences. Therefore, it was difficult to obtain an optimal sequence of multilayered foam-panel structure yielding superior sound isolation capability. In this work, we propose a new design method to sequence a multi-panel structure lined with a poroelastic material having maximized sound transmission loss. Being formulated as a one-dimensional topology optimization problem fur a given target frequency, the optimal sequencing of panel-poroelastic layers is systematically carried out in an iterative manner. In this method, a panel layer is expressed as a limiting case of a poroelastic layer to facilitate the optimization process. This means that main material properties of a poroelastic material are treated as interpolated functions of design variable. The designed sequences of panel-poroelastic multilayer were shown to be significantly affected by the target frequencies; more panels were obtained at higher target frequency. The sound transmission loss of the system was calculated by the transfer matrix derived from Biot's theory.

• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.60-65
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• 2015

This study is to explore floor impact sound and sound insulation of reinforced concrete structure with void-deck slab system which combines polystyrene void foam and T-shaped steel deck plate. A void-deck slab system can effectively reduce the amount of concrete used and hence the mass of a reinforced concrete slab. Also void slab system has dynamically favorable for bending. Three-bay 2-story building was constructed as a mock up test specimen using void-deck slab system and floor impact sound was measured to valuate sound insulation performance. Light weight floor impact and heavy weight floor impact were investigated. Light weight floor impact pressure levels were 32dB, 28dB, and 29db at representative locations which are $1^{st}$ level in the floor impact sound insulation performance grading system. The heavy-weight floor impact pressure levels were 44dB, 45dB, and 43dB at representative locations which are $2^{nd}$ level in the floor impact sound insulation performance grading system. Therefore void-deck slab system can be used in public housing apartment building in terms of not only effectively reduced construction materials but also floor impact sound insulation.

• Journal of the Korean Society of Safety
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• v.26 no.3
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• pp.23-28
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• 2011

This paper studied combustion characteristics of the building materials such as polyurethane-foam, sponge type sound-absorbing materials and styrofoam. To estimate of the combustion characteristics, we carried out combustion experiment of the building materials. And then to evaluate the suitability of the building materials, we measured heat release rate(HRR) and smoke density(Ds) of polyurethane-foam, sponge type sound-absorbing materials and styrofoam using by a cone-calorimeter. From the combustion experimental results, the general type sound-absorbing materials (GSAM) and styrofoam were rapid burned simultaneously with ignition and the incombustibility type sound-absorbing materials(ISAM) and polyurethane-foam had all gone out simultaneously with ignition. Measured results of HRR and Ds were not satisfied KS F ISO 5660-1 and IMO FTP Code, from the results, the polyurethane-foam, the sponge type sound-absorbing material and the styrofoam were ill-suited for using building interior materials.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.309-314
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• 2007

Optimal layer sequencing of a multi-layered acoustical foam is solved to maximize its sound transmission loss. A foam consisting of air and poroelastic layers can be optimized when a limited amount of a poroelastic material is allowed. By formulating the sound transmission loss maximization problem as a one dimensional topology optimization problem, optimal layer sequencing and thickness were systematically found for several frequencies. For optimization, the transmission losses of air and poroelastic layers were calculated by the transfer matrix derived from Biot's theory. By interpolating five intrinsic parameters among several poroelastic material parameters, dear air-poroelastic layer distributions were obtained; no filtering or post-processing was necessary. The optimized foam layouts by the proposed method were shown to differ depending on the frequency of interest.