• Title/Summary/Keyword: Absorbing Ratio

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Mechanical Characteristics for Pulp Molds Made of ONP and OCC with Different Mixing Ratio (고지배합비율에 따른 펄프몰드 물성 변화 연구)

  • Park, In-Sik;Kim, Jae-Nung;Kim, Dae-Yong
    • Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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    • 2007.04a
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    • pp.285-297
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    • 2007
  • As the demands of environment protection increase, the pulp mold container is developed to substitute for the plastic cushion materials like EPS(expanded poly styrene). The water-absorbing ratio, tensile strength and compressive strength of pulp mold are important factors to evaluate its shock absorbing characteristics. The study was performed to investigate the effects of the mechanical property changes on the various conditions of temperature and relative humidity for pulp mold containers made of mixed materials on ONP(old newspaper) and OCC(old corrugated container). This study also is evaluated the optimized mixing ratio of materials for making pulp mold by analyzing the changes of physical properties according to a various procured temperature and relative humidity conditions. The results show that the water absorption ratio of sample increased significantly, and tensile strength decreased $20{\sim}30%$, compressive strength decreased $10{\sim}20%$ by increasing relative humidity condition. And the results show that the ONP 50% and OCC 50% was optimized mixing ratio according to the samples.

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An Experimental Study on the Properties of Lightweight Aggregate Concrete Using Waste PET Bottles (폐 PET병을 이용한 경량골재콘크리트의 특성에 관한 실험적 연구)

  • 최연왕;정지승;문대중;신화철;황윤태
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.211-216
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    • 2002
  • Recently, the more the PET bottles are needed, the more waste PET bottles were produced. So, if there was no suitable recycling, that was contaminate our environment and use up the natural resources. This paper deals with the artificial lightweight aggregate(ALA), made of waste PET bottles, and the properties of concrete replaced with ALA. As a result of experiment, it is shown that the specific gravity of PBLA is 1.39, the unit volume weight is 844 kg/$cm^3$, and absorbing rate is 0. In absorbing rate test, the rate is 10 % increased by replacing of 20 % PBLA and the mixture rate for water and cement is 44.6 % and 51.2 %, in case target strength for 240kgf/$cm^2$, and 270kg/$cm^2$, by added PBLA 75 % and 50 % respectively. So, to obtain a certain target strength, appropriate W/C ratio is required the replacement ratio of PBLA.

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The Collapse Characteristics of Vehicle Thin-walled Members Coated Damping Material (댐핑재가 도포된 차체 박육부재의 압궤특성)

  • 송상기;박상규;송찬일
    • Journal of Advanced Marine Engineering and Technology
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    • v.27 no.1
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    • pp.76-81
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    • 2003
  • The purpose of this study is to analyze the collapse characteristics of widely used spot welded section members coated damping material Y1000 and to develop an analysis method for acquiring exact collapse loads and energy absorption ratio. Hat-shaped thin-walled members have the biggest energy absorbing capacity in a front-end collision. The sections were tested on quasi-static and impact loads. Specimens with two type thickness, width ratio and spot weld pitch on the flange have been tested in impact velocities(6.73n0sec and 7.54n1sec) which imitate a real-life car collision. As a result, it was developed the system for acquiring impact energy absorbing characteristics of structure united thin-walled member and damping materials.

The Estimation of Firing Temperature of Clay Brick used in Modern Architecture (근대 조적건축물에 이용된 점토벽돌의 소성온도 추정)

  • Kwon, Eun-Hee;Ahn, Jae-Cheol;Kang, Byeung-Hee;Kim, Ki-Soo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2011.05a
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    • pp.103-105
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    • 2011
  • The purpose of this study is to suggest basic data which is firing technique at manufacturing time for preservation and rehabilitation of masonry modern architecture by assumed firing-temperature. It could be possible to estimate firing-temperature at manufacturing time through the result of the experiments, XRD and changed absorbing ratio from re-firing.

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Engineering Properties of Sound Absorbing Foamed Concrete Using Bottom Ash Depending on Mix Factors (배합요인에 따른 바텀애시 미분말을 사용한 흡음형 기포콘크리트의 공학적 특성)

  • Kim, Jin-Man;Kang, Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.9 no.5
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    • pp.63-70
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    • 2009
  • This study is part of an ongoing research project on the development of a sound-absorbing lightweight foamed concrete manufactured by a hydro-thermal reaction between silica and calcium. As the silica source, pulverized bottom ash was used, and as several cementitious powders of ordinary portland cement, alumina cement and calcium hydroxide were used. Manufacture of foamed concrete was accomplished using the pre-foaming method to make a continuous pore system, which is the method of making the foam by using a foaming agent, then making the slurry by mixing the foam, water, and powders. The experiment factors are W/B, foam agent dilution ratio, and foam ratio, and test items are compressive strength, dry density, void ratio, and absorption rate, as evaluated by NRC. The experiment results showed that the sound absorption of lightweight foamed concrete satisfied NRC requirements for the absorbing materials in most of the experiments. It is thus concluded that foam ratio was the most dominant factor, and significantly affected all properties of lightweight foamed concrete in this study. W/B rarely affected total void ratio and continuous void ratio as well as compressive strength, and dry density and foam agent dilution ratio also had little effect onalmost all properties. The analysis of the correlation between NRC, absorption time, continuous void ratio, and absorption time showed that the interrelationship of the continuous void ratio was high.

Developments of monitoring system to measure sound absorbing coefficient and structural stability of sound absorbing panel on the concrete track in the urban train tunnel (도시철도 터널 내부 콘크리트 도상 국소공명흡음판의 흡음계수 및 구조안정성 평가를 위한 계측시스템 개발)

  • Oh, Soon-Taek;Lee, Dong-Jun;Lee, Dong-Hoon
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.19 no.1
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    • pp.1-9
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    • 2017
  • In this study, a test-bed system simulated a tunnel and concrete track is tested on cite and invested an allowed limit of multi-layered sound absorbing panel for reducing noise reflected on the concrete track in train tunnel considering the criteria and limitation on the theoretical back ground. The studied results are an effective evaluating system of the sound absorbing coefficient influenced fluid effects depending on the vehicle speed in the urban train tunnel and measuring not only structural behaviors of maximum displacement and acceleration of the panel but also dynamic characteristics of damping ratio and natural frequency.

Experimental Study on the Properties of Solid Material Made by Autoclave Curing according to CaO/SiO2 Ratio and W/B (CaO/SiO2비 및 W/B 변화에 따른 오토클레이브 양생 경화체의 특성에 관한 실험적 연구)

  • Kang, Cheol;Kang, Ki-Woong;Kim, Jin-Man
    • Journal of the Korea Concrete Institute
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    • v.21 no.5
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    • pp.557-563
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    • 2009
  • This study is on the properties of inorganic porous calcium silicate material made from silica powder through the autoclaving curing, the results of this study should be utilized fundamental data for the development of noise reduction porous solid material using siliceous byproduct generated by various manufacture process. For the manufacture of autoclave curing specimen, various calcareous materials used and siliceous materials used silica powder. In this study, properties in density and compressive strength according to the change of W/B and C/S ratio, microscopy for the shape of pore, SEM and XRD for the examination of hydrate after autoclave curing are carried out respectively. The test results shown that the more slurry density decrease, the more W/B increase at the fresh state, this tendency shown similar to in hardened state. Among the specimens of C/S ratio, the compressive strength of C/S ratio of 0.85 gave the highest the compressive strength. In the results of XRD, tobermorite generated by autoclaving curing was created all of specimens regardless of C/S ratio. To ascertain pore structure, we compared with existing porous calcium silicate product(ALC, organic sound absorbing porous material). The results of microscope observation, pore structure of specimen of this study was similar to that of existing inorganic sound absorbing foam concrete. therefore, we could conformed a possibility of sound absorbing porous solid material on the basis of the results.

Microwave Absorbing Properties of Rubber Composites Containing Soft Magnetic Fe-Alloy Particles (철계 연자성 합금 분말을 함유한 고무 복합재의 전파흡수특성)

  • Cho, Han-Shin;Kim, Sung-Soo
    • Journal of Powder Materials
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    • v.20 no.2
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    • pp.125-128
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    • 2013
  • Magnetic and dielectric properties of rubber composites are controlled by using two kinds of high-permeability metal particles with different electrical conductivity (Sendust, Permalloy), and their effect on microwave absorbance has been investigated, focusing on the quasi-microwave frequency band (0.8-2 GHz). Noise absorbing sheets are composite materials of magnetic flake particles of high aspect ratio dispersed in polymer matrix with various filler amount of 80-90 wt.%. The frequency dispersion and magnitude of complex permeability is almost the same for Sendust and Permalloy composite specimens. However, the complex permittivity of the Permalloy composite (${{\varepsilon}_r}^{\prime}{\simeq}250$, ${{\varepsilon}_r}^{{\prime}{\prime}}{\simeq}50$) is much greater than that of Sendust composite (${{\varepsilon}_r}^{\prime}{\simeq}70$, ${{\varepsilon}_r}^{{\prime}{\prime}}{\simeq}0$). Due to the large dielectric permittivity of Permalloy composite, the absorbing band is shifted to lower frequency region. However, the investigation of impedance matching reveals that the magnetic permeability is still small to satisfy the zero-reflected condition at the quasi-microwave frequency band, resulting in a small microwave absorbance lower than 10 dB.

Numerical Study On Combined Natural Convection-Radiation In Partially Open Square Compartments with A Heater (발열체가 있는 열린 공간내에서의 자연대류-복사열전달 현상에 관한 수치적 연구)

  • 손봉세;한규익;서석호;이재효;김태국
    • Fire Science and Engineering
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    • v.9 no.1
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    • pp.10-19
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    • 1995
  • Study on combined natural convection-radiation In partially open square enclosures filled with absorbing-anisotropic scattering media is performed. A heater block located in the enclosure causes the natural circulation of the fluid in the enclosure which results In significant in-flow of the cold fluid through the partially open wall. Four different locations of the heater are considered to observe the effect of the heater locations on the resulting heat transfer. Results obtained from the combined convection-radiation analyses show much stronger circulation of t he fluid inside the enclosure as compared to those obtained from the pure convection analyses. As the ratio of the open area is Increased, the inflow of the cold fluid and the circulation of the fluid inside the enclosure is increased causing lower fluid temperature Inside the enclosure. It is shown that the location of the heater influences the circulation and heat transfer significantly by showing stronger circulations and more uniform temperature distributions for the cases where the heater is located on the bottom wall as compared to those for the cases where the heater is located on the upper part wall of the enclosure. For pure absorbing medium, the expected circulation in the fluid is relatively week as compared to those with absorbing-scattering medium due to the smaller wall heating as the radiant heat is used to heat the fluid instead. The forward anisotropic scattering phase function is shown to increase the fluid circulation further as compared to the isotropic scattering medium.

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The Material Constants and Microwave Absorbing Characteristics of ferroxplana Composite Microwave Absorber (복합 ferroxplana 전파흡수체의 재료정수와 전파흡수 특성)

  • 신재영;오재희
    • Journal of the Korean Magnetics Society
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    • v.1 no.2
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    • pp.49-54
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    • 1991
  • In this study the correlation between material constants and microwave absorbing characteristics of ferroxplana composite microwave absorber used in X-band was investigated. The real part of permeability(${\mu}_{r}'$) was decreased and the imaginary part of permeability(${\mu}_{r}"$) of ferroxplana composite was increased with increaing ferroxplana loading ratio(F/R). The frequency showing maximum attenuation was shifted to lower frequency with increasing absorber thickness. The absorber 2.6 mm thick showed good band width property and 3.2 mm thick showed good attenuation property. From the apphcation of ferroxplana composite's material constants to the region of material constants which satisfy broad band width, it is found that the absorbing characteristics were estimated quantitatively. Estabhshment of material constants' region which satisfies broad band width can make practical application to design of high performance ferrite microwave absorber.

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