• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.377-380
• /
• 2005

Damping materials encompass a broad range of materials, including, but not limits to, pressure sensitive adhesives, epoxies, rubbers, foams, thermoplastics, enamels and mastics. Their common characteristic is that their modulus is represented by a complex quantity, possessing both a stored and dissipative energy component. Loss factor of damping material analyzed more than 2 times than rubber to 1.5 $\sim$ 2.3, could know that Damping layer has excellent attenuation performance in side of vibration reduction. Measurements of vibration using accelerometers by adhesion of Damping layer, square Plate by Separation of Damping layer is less binding of Damping layer, analyzed low loss factor and Natural Frequency by free Vibration of Square Plate.

• The Journal of the Acoustical Society of Korea
• /
• v.42 no.6
• /
• pp.565-571
• /
• 2023

With the introduction of the post-verification system, the measurement of floor impact noise performance on-site has become mandatory, and the evaluation method has changed. To track the performance changes since the policy implementation, research is needed on how the characteristics of heavyweight impact sound change according to the varied evaluation method. In this study, we analyzed the contribution rate of the frequency band-specific sound pressure level on the single-number quantity for a multi-family housing unit with the same floor plan and floor structure, comprising 59 households, based on the changed impact sources and evaluation indicators. It is difficult to compare simply because the method of calculating contributions by frequency band according to the single-day evaluation is different, but the average contribution rate of 63 Hz was 80.8 % in the evaluation method before the introduction of the post-confirmation system (Tire measurement and evaluated as L'_i,Fmax,AW), and the average contribution rate of 125 Hz was 19.2 %. The current evaluation method (rubber ball measurement and evaluation as L'_iA,Fmax) shows that the contribution rate has decreased to 33.1 % on average at 50 Hz ~ 80 Hz, 58.7 % on average at 100 Hz ~ 160 Hz, 6.9 % on average at 200 Hz ~ 315 Hz, and 1.3 % on average at 400 Hz ~ 630 Hz. This result is a case analysis for the target apartment house, and it is necessary to analyze measurement data for more diverse apartment houses.

• The Journal of the Acoustical Society of Korea
• /
• v.42 no.6
• /
• pp.594-602
• /
• 2023

To date, research on heavy floor impact noise has mainly been conducted. The reason is that in the case of lightweight floor impact noise, sufficient performance could be secured with only the floating floor structure and floor finishing materials. In the case of heavy floor impact noise in a floating floor structure, the reduction performance can be predicted to some extent by measuring the dynamic elasticity of the floor cushioning material. However, with the recent introduction of the post-measurement system, various floor structures are being developed. In particular, many non-floating floor structures that do not use cushioning materials are being developed. In floor structures where cushioning materials are not used, the finishing material will have a significant impact on lightweight floor impact noise. However, research on floor finishing materials is currently lacking. In this study, as a basic research on the development of various floor finishing materials for effective reduction of lightweight floor impact noise, various materials used as floor finishing materials for apartment complexes were selected, the sound insulation performance of lightweight floor impact noise was measured in an actual laboratory, and vibration characteristics were identified through simple experiments. The purpose was to confirm the predictability of light floor impact noise.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.10
• /
• pp.1006-1013
• /
• 2008

In this study, it is outlined that heavy weight floor impact noise induced by the vibration of slab can be reduced using multi tuned mass damper(MTMD) effectively. Substructure synthesis is utilized to develope analytical model of the slab coupled with MTMD and acoustic power is introduced to evaluate the performance of noise control for simplicity. Numerical analysis is carried out to investigate the effect of the properties of MTMD on the vibration and noise control of the simply supported slab. Numerical analysis shows that mass ratio of MTMD is critical on the vibration and noise control of the slab and it is also essential to reduce the vibration in higher modes of slab in the light of its great effect on the radiation of sound.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.04a
• /
• pp.659-664
• /
• 2008

In this study, it is outlined that heavy weight floor impact noise induced by the vibration of slab can be reduced by multi tuned mass damper(MTMD) effectively. Substructure synthesis is utilized to develope analytical model of slab coupled with MTMD and acoustic power is introduced to evaluate the performance of noise control for simplicity. Numerical analysis is carried out to investigate the effect of the properties of MTMD on the vibration and noise control. Numerical analysis shows that mass ratio of MTMD is critical on the vibration and noise control of the slab and it is essential to reduce the vibration in higher modes of slab because it has a great effect on the radiation of sound.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.12 no.6
• /
• pp.437-444
• /
• 2002

This paper is to provide the basic way of a acoustical evaluation and efficient control noise by investigating the limits of perceptual loudness of living environment and by finding out any correlation between Physical characteristics of noise and psychoacoustic parameters. The limits of perceptual loudness were selected by the subjects in a chamber for residential and working environment. And the noise sources were analyzed to find out whether there is any correlation with Zwicker parameters and ACF factors. In this study especially, to set up the domestic evaluation grade about floor impact noise. we'd like to suggest the loudness Perception research result as fundamental resource for setting up the evaluation grade through the result that is based on annoyance. In the result of this research, upper limit of heavy-weight impact noise was L-60, and lower limit of it was L-50. On the other hand, upper limit of light-weight impact noise was L-70, and lower limit of it was L-55. It seemed that the loudness of noise from vacuum cleaner noise does not affect its perceived noisiness. Noises implicated In human such as floor walking noise and talking sound, are the most irritating noise in office environment.

• Advanced Composite Materials
• /
• v.17 no.1
• /
• pp.25-40
• /
• 2008

The research and development in soundproof materials for preventing noise have attracted great attention due to their social impact. Noise insulation materials are especially important in the field of soundproofing. Since the insulation ability of most materials follows a mass rule, the heavy weight materials like concrete, lead and steel board are mainly used in the current noise insulation materials. To overcome some weak points in these materials, fiber reinforced composite materials with lightweight and other high performance characteristics are now being used. In this paper, innovative insulation sheet materials with carbon and/or glass fabrics and nano-silica hybrid PU resin are developed. The parameters related to sound performance, such as materials and fabric texture in base fabric, hybrid method of resin, size of silica particle and so on, are investigated. At the same time, the wave analysis code (PZFlex) is used to simulate some of experimental results. As a result, it is found that both bundle density and fabric texture in the base fabrics play an important role on the soundproof performance. Compared with the effect of base fabrics, the transmission loss in sheet materials increased more than 10 dB even though the thickness of the sample was only about 0.7 mm. The results show different values of transmission loss factor when the diameters of silica particles in coating materials changed. It is understood that the effect of the soundproof performance is different due to the change of hybrid method and the size of silica particles. Fillers occupying appropriate positions and with optimum size may achieve a better effect in soundproof performance. The effect of the particle content on the soundproof performance is confirmed, but there is a limit for the addition of the fillers. The optimization of silica content for the improvement of the sound insulation effect is important. It is observed that nano-particles will have better effect on the high soundproof performance. The sound insulation effect has been understood through a comparison between the experimental and analytical results. It is confirmed that the time-domain finite wave analysis (PZFlex) is effective for the prediction and design of soundproof performance materials. Both experimental and analytical results indicate that the developed materials have advantages in lightweight, flexibility, other mechanical properties and excellent soundproof performance.

• Journal of the Korean Wood Science and Technology
• /
• v.33 no.6 s.134
• /
• pp.8-16
• /
• 2005

Fire-killed trees of Korean red pine are valuable resources for industrial uses. It is common only believed that fire-killed trees are too weak and brittle to use in construction purposes. The misunderstandings of fire-killed trees lead these valuable resources abandonment. The purposes of this research are focused on scrutinization of material properties of fire-killed trees to facilitate industrial uses of these resources. The sample logs were collected from the forest fire site of the eastern coast area in which the most catastrophic wild fire had taken place in 2000. Fire-killed Korean red pines were classified into 3 levels by the degree of fire damage so called light, medium and heavy, then their physical, mechanical and chemical properties were compared with sound trees. No significant difference in physical appearances were found in the cross sections by degree of damage compared to sound tree but bark char. Investigation on mechanical and chemical properties indicates that forest fire did not impact significantly in lowering the strength of damaged trees. It was concluded that there was any limitation of forest fire-killed trees of Korean red pine in industrial utilization.

• Journal of Soil and Groundwater Environment
• /
• v.13 no.2
• /
• pp.12-20
• /
• 2008

This study was conducted to investigate the spatial distributions of chromated copper arsenate (CCA) metals in soils around three log structures and a sound barrier, all built with CCA-treated wood. Sixty-six surface and 35 profile soil samples were collected around the wood structures in addition to 13 background soil samples. The concentrations of chromium, copper, and arsenic in the soil samples collected in the vicinity of the structures were higher than those in the background samples, except in the case of one structure. The concentrations in the surface soils adjacent to the 3-year-old structures seemed to be higher than those in the soils adjacent to the 8-year-old ones. Although the lateral distributions of the metals varied with the structures, chromium and arsenic appeared to show concentration gradients within 20-60 cm and 40-100 cm, respectively. Copper seemed to be the least mobile, displaying concentration gradients only within 20 cm. Even though there were no explicit vertical concentration gradients for any of the metals according to the profile soil sample analysis, chromium and copper seemed to show concentration gradients only up to 5 and 10 cm, respectively, whereas arsenic showed gradients up to 35 cm. At study sites, it was evident that heavy metals leached into soil from CCA-treated wood were confined to neighboring areas both laterally and vertically, and that any plausible ecological impact may occur only within a small range.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.7
• /
• pp.677-685
• /
• 2005

Life Cycle Assessment(LCA) and Design for Environment(DfE) method were applied to design the environmentally sound manufacturing process of f31k lift in this study. Not only external movement of LCA and DfE method in the legal and systemic phase, but also active researches of those in the development phase of case study and application to the industrial field, have been going on. In concretely, the manufacturing processes of the folk lift generating the most environmental impact were examined by applying LCA method, and the environmentally sound manufacturing process was designed by applying, DfE method to the processes. As the results of LCA, environmental impacts for the eco-toxicity and human toxicity of seven major environmental categories were in high value, and so be in the cutting & welding process and painting process among the manufacturing processes. High solid paints, increasing the solid content of the existing solvent paints used in painting process, were developed to reduce the environmental impacts generated in the painting process. By utilizing the high solid paints, about 20% of environmental impacts (as environmental index of LCA) could be reduced.