• 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.

• 한국도로학회지:도로
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• v.11 no.2
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• pp.26-33
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• 2009

본 특집기사는 미국 NCAT(National Center for Asphalt Technology)에서 실험한 보고서(Hurley 및 Prowell, Evaluation of Sasobit for Use in Warm Asphalt, 2005)를 정리한 것으로 아스팔트 중온포장에 대해 연구하는 사람들에게 어느 정도 도움을 주고자 일부 내용을 번역하였다. 특히, 골재와 바인더 믹싱 및 현장다짐시 온도를 낮추어 궁극적으로 $CO_2$를 저감하고자 하는 노력이 많은 아스팔트 포장관련 종사자 및 연구자들에 의해 활발히 수행되고 있다. 본 기사에서는 중온에서도 작업성을 원활하게 하기 위해 사용되는 많은 첨가제 중 Fischer-Tropsch 왁스인 Sasobit에 대해 살펴보고자 한다. 여기서 관심을 두고자 하는 점은 중온 아스팔트를 실제로 활용할 시 과연 일반 아스팔트 포장과 비교했을 때 어느 정도의 공용성(Performance)을 확보할 수 있느냐 하는 점이다. NCAT의 실내실험을 통해 알아낸 결과로는 진동다짐기를 이용하는 것이 보다 현실적이라는 것과 중온다짐에 따른 아스팔트의 동탄성 계수의 변화가 적다는 것이다. 또한 APA(Asphalt Pavement Analyzer)를 통해 소형변형의 가능성이 높지 않음을 알 수 있었으며, 중온 아스팔트를 사용함에 따른 일반적인 문제점인 수분민감성이 커지는 현상에 대해서 실험을 통해 검증한 결과, 박리방지제를 쓰는 것이 좋다는 결론을 얻었다. 전반적으로 Sasobit의 실내공용성 평가는 우수하다고 보고되고 있다.

• International Journal of Highway Engineering
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• v.15 no.3
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• pp.65-74
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• 2013

PURPOSES: This study is to evaluate the dynamic modulus changes of permeable asphalt mixtures by using non-destructive impact testing method and to compare the dynamic moduli of permeable asphalt mixtures through repeated freezing and thawing conditions. METHODS: For the study, non-destructive impact testing method is used in order to obtain dynamic modulus of asphalt specimen and to confirm the change of dynamic modulus before and after freezing and thawing conditions. RESULTS : This study has shown that the dynamic moduli of asphalt concrete specimens consisting of 10%, 15% and 20% porosity are reduced by 11.851%, 1.9564%, 24.593% after freezing and thawing cycles. CONCLUSIONS : Non-destructive impact testing method is very useful and has repeatability. Specimen with 15% porosity has high durability than others.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.4
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• pp.75-81
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• 1997

This study was performed to evaluate the engineering properties of surlightweight polymer concrete using synthetic lightweight aggregate. The following conclusions were drawn; 1. The unit weight was in the range of 0.849~0.969t/$m^3$, the unit weights of those concrete were decreased by 58 ~ 63% than that of the normal cement concrete. 2. The highest strength was achieved by $P_1$, and compressive strength was increased by 93% and bending strength by 364% than that of the normal cement concrete, respectively. 3. The ultrasonic pulse velocity was in the range of 2, 346~2, 702m/s, which was low compared to that of the normal cement concrete. 4. The dynamic modulus of elasticity was in the range of $1.561{\times} 10{^5}~1.916{\times} 10{^5}kgf/cm^2$, which was approximately 52~98% of that of the normal cement concrete. 5. The compressive and bending strength were increased with the increase of unit weight. But, the dynamic modulus of elasticity and ultrasonic pulse velocity were decreased with the increase of unit weight.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.211-212
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• 2010

This study is aimed to investigate effects of water-cement ratio on the freeze thaw resistance of fly ash concrete. Assess the effects of physical properties of fly ash concrete by measure the length change, weight change, dynamic modulus of elasticity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1393-1400
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• 2002

A double cantilever sandwich-beam method has been applied to the evaluation of the frequency dependence of dynamic elastic modulus and material loss factor of EPDM rubbers. The flexural vibration of a double cantilever sandwich-beam specimen with an inserted rubber layer was studied using a finite element simulation in combination with the sine-sweep test. Effects of the rubber layer length on the dynamic characteristics were also investigated: reliable values were measured when the length of the inserted rubber layer was larger than and equal to 50% of the effective specimen length. The values were compared with those obtained by the dynamic mechanical analysis and the simple resonant test. Relationships of the dynamic characteristics of rubbers with frequency could be determined using the least square error method.

• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.499-504
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• 2004

The purpose of this study is to investigate a investigating of a floor-impact isolation system using damping materials in apartment buildings. The stiffness elastic modulus(k) by puls impact forces were calculated loss factor by Hilbert transforms. It is absolved that natural frequency was moved floor shock-absorbing materials and the impact force was reduced by floor panel. The slab was constructed by damping materials. As towards a result, the system showed inverse A 45dB by heavy weight-impact noise and inverse A 52dB by light-impact noise. High frequencies impact-noise can be reduced by upgrading naturial frequency of vibration and noise in the system.

• Journal of the Korean Society of Industry Convergence
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• v.12 no.3
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• pp.149-155
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• 2009

A new finite element equation is derived by applying quadratic and cubic time integration scheme to the variational formulation in time-integral for the analysis of the transient elastodynamic problems to increase the numerical accuracy and stability. Emphasis is focused on methodology for cubic time integration scheme procedure which are never presented before. In this semidiscrete approximations of the field variables, the time axis is divided equally and quadratic and cubic time variation is assumed in those intervals, and space is approximated by the usual finite element discretization technique. It is found that unconditionally stable numerical results are obtained in case of the cubic time variation. Some numerical examples are given to show the versatility of the presented formulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1425-1431
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• 2006

In this study, An analysis of correlation between the vibration transmissions and the dynamic characteristics for floor impact sound insulation materials through model test was carried out. As the results, the correlation coefficients between the vibration transmissions and the dynamic characteristics for floor impact sound insulation materials were over 0.8 at the heavy and light floor impact source and less dynamic stiffness was more effective in reducing the vibration transmission.