• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.7
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• pp.253-260
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• 2001

A Study of interior noise reduction in the magelv train is presented. Tarin speed of interest is low such that aero-dynamic noise is negligible and power supply system is a dominant noise source. Based on the measurements of interior noise and acceleration levels during running and zero speed conditions, dominant noise sources are identified. After spectra characteristics of noise sources are investigated several noise reducing methods are studied such as STL increasement of floor panels. sealing. and absorption treatment It is found that the most important noise sources are VVVF inverter and SLM in running condition, whereas air conditioner and DC/DC converter are dominant in zero speed. Sine the major noise sources are under the floor complete sealing and high STL of the floor panel are shown to be the most crucial factors in noise reduction After sound absorbing material, which is polyurethan foam of 50 mm thickness, is thickness, is attached to the downward side of the floor in addition to sealing treatment, the interior noise is reduced by 3~4 dB.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.141-142
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• 2015

This literature study is focused on the improvement of lightweight concrete in perspective of foaming agent. Lightweight concrete is the cured concrete as putting required amount of foaming agent to slurry which is a mixture of a certain amount of cement, sand, and water. It has lower density than general concrete, because foaming agent disintegrates numerous bubbles evenly and independently. Thus, it is capable of lightening the weight and great for sound absorption and insulation, In foreign countries, studies for structural lightweight concrete mainly of tunnel grouting and weight lightening of heavy structures are going along actively. Domestically, exterior panel and ALC blocks are alternatively used for flooring. Therefore, this research consider improvement of lightweight concrete in perspective of foaming agent with foundation study.

• Magazine of the Korea Concrete Institute
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• v.10 no.1
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• pp.171-178
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• 1998

본 연구는 폴리우레탄 콘크리트 패널의 바닥재로서의 이용 가능성을 검토하기 위하여 수행되었다. 따라서 각종 요구되는 성능에 부합되는 배합을 달리한 폴리우레탄 콘크리트를 제작하여 각종 물성 실험을 실시하였다. 또한 폴리우레탄 콘크리트 패널을 제작하여 직접 현장에서의 시공한 수 바닥충격음 실험을 실시, 그 효과를 평가하였다. 실험결과, 폴리우레탄 콘크리트의 성능과 코스트의 밸런스가 적절하게 확보된 최적배합비를 도출할 수 있었으며, 특히 기존 바닥구조에 비해 공동주택의 층간소음을 어느 정도 줄일 수 있고 동시에 시공공정의 단축과 단열효과로 보다 더 우수한 바닥난방구조를 제안할 수 있다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.98-101
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• 1997

Membrane panels for LNG(Liquid Natural Gas) tank are formed to corrugared ones by press forming. The environment of LNG tank is so severe that the service temperature is -162$^{\circ}C$ and the room temperature is 20$^{\circ}C$. The thermal deformation derived by the severe temperature change is absorbed by the corrugations of the membrane panels. In this paper the formability of stainless steel membrane panel is examined by the finite element analysis. Two corrugated shapes are suggested, and analyzed to obtain a sound absorption performance of the thermal distortion. Also the design considers forming characteristics and economy of production.

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

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.666-671
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• 2018

A honeycomb panel is a plate made by attaching two surface plateson eitherside of a honeycomb core. The honeycomb plate hasexcellent specific strength and energy absorption and is suitable for use in regions where good impact resistance is required. Recently, with the increasing the need for a lightweight design to facilitate transportation, numerous studies have been conducted using aluminum honeycomb plates as body materials for vehicles such as automobiles and high-speed trains. In addition, honeycomb plates have excellent sound deadening properties, as well as excellent heat insulation and durability. Savings in weight using lightweight materials such as aluminum alloy for honeycomb panel's skin can lead to increase fuel economy and reduction in air pollution. In this study, in order to improve the design technology of the honeycomb plate material, the manufacturing technology of the aluminum honeycomb core and honeycomb plate material and various mechanical properties of the honeycomb plate were evaluated. From the results, it was found that the design of the manufacturing process of the aluminum honeycomb plate, as well as itsproduction and characteristics, were improved. The resulting excellent energy absorption capability of the honeycomb plate was due to the repetitive core buckling, indicating that the higher the compressive strength, the higher the strength per bonded area.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.645-657
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• 2015

In this study floor impact noise and structure acceleration response of bare concrete slabs were predicted by using Finite Element Analysis(FEA). Prediction results were compared with experimental results to prove the accuracy of numerical model. Acoustic absorption were addressed by using panel impedance coefficients with frequency characteristics and structural modal damping of numerical model were applied by modal testing results and analysis of prediction and test results. By using frequency response function, the floor acceleration and acoustic pressure responses for various impact sources were calculated at the same time. In the FEA, the natural frequencies and the shapes of vibration and acoustic modes can be estimated through the eigen-value analysis, and it can be visually seen the vibration and sound pressure field and the contribution of major modes.

• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.371-379
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• 2016

In this article, the foamed body of glass was manufactured from the waste borosilicate glass produced by wet pulverization process without additional pretreatment which can be used as a recycling method for waste LCD panel glass. Each 100 g of pulverized waste borosilicate glass with the size of less than 270 mesh were mixed with 0.3 weight fraction of carbon and 1.5 weight fraction of $Na_2CO_3$, $Na_2SO_4$ and $CaCO_3$ and let them foamed for 20 minutes at $950^{\circ}C$ to manufacture the foamed body having the density of less than $0.3g/cm^3$. Additionally, adding $SiO_2$ or $H_3BO_3$ to the mixture enabled the foamed body to have efficient formation of open pores which showed the possibility for producing the foamed body with new functionalities such as sound absorption.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.198-201
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• 2001

Porous structures of aluminum foam have been studied by using return aluminum scrap. The apparent foam shape, foam height, density, pore size and their distributions in various section areas of the experimental samples have been investigated. The sample have been cast into metallic mold, using aluminum foam prepared from a precursor based on pure Al ingot and return aluminum scrap mixed with various amounts of 1-2wt% increasing viscosity and foam agent materials. The process provides for flexibility in design of foam structures via relatively easy control over the amount of hydrogen evolution and the drainage processes which occur during foam formation. This is facilitated by manipulating parameters such as the foaming agent, thermal histories during solidification and mix melt viscosities. A metal for producing the foamed are decomposing a foaming agent in a molten metal such that there is an initial and a subsequent expansion due to foaming agent. It has been found that the Al porous foaming with variation amount of 1∼2wt% foam agent and at 2min holding time, which melting temperature has appeared homogeneous pore size at 650∼700$^{\circ}C$. The compression strength were 10-13 kg/min at 125ppi, and increased by higher pore density. The acoustical performance of the panel made with the foamed aluminum is considerably improved; its absorption coefficient shows NRC 0.6-0.8. It has been found that the Al foam is very preferable for the compactness of the thermal system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.35-41
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• 2008

Qualitative enhancement of dwelling life has changing the recognition for the environment friendly wood which is being highlighted for its usage as an interior materials. This trend may prove the excellent performance of wood whose inherent characteristics has its comfortable, mild feeling of material, sound resistance and stabilities and the market of interior woods including floor, moulding and wooden panel as finishing interior materials is growing sustainably. However, since this materials is vulnerable to humidity and flame, waterproofing and flame retarding stability, an essential condition for interior materials, together with maintenance, are the main topics to be resolved. From the above-mentioned results, as a result of waterdrop contact angle, wood absorption volume and water content percentage test and the performance test of the processed materials after flame retardant, though there was some submerging time changes among types of woods for ensuring waterproofing performance improvement but as time passes, similar tendency was noticed to be formulated. As the submerging time is increased, so does the absorption volume and accordingly optimal level of range is judged to be drawn in order to ensure excellent performance, taking optimal economy into consideration. Therefore, it is considered that above-mentioned woods could be utilized for waterproof and flame retardant processed interior materials using uniform microwave and in order to put this technology into practical application, a research by way of diversified performance proving is required to be carried out.