• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.32-33
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• 2019

This study evaluated the effect of amorphous steel fibers on the spalling characteristics of high-strength concrete. with mix proportions of polypropylene (PP) fibers of 0.15% by concrete volume, and proportions of amorphous steel fibers of 0.3% and 0.5% by concrete volume. In the range of 0.3 vol% of amorphous steel fiber, the effect of suppression of the spalling and the prevention of degradation of strength was shown, but it was evaluated to be ineffective in the suppression of the spalling due to interferences in formation of pore network in the range of 0.5 vol.%.

• 한국토양비료학회지
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• 제13권2호
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• pp.57-63
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• 1980

시판(市販)되고 있는 광재규산질비료를 사별(篩別)하여 10목이하(目以下) 20-35목(目) 및 100목이상(目以上)의 3개입자군(個粒子群)으로 분리(分離)하고 그들을 토양(土壤)에 처리했을 때 토양용액(土壤溶液)의 규산함량변화(珪酸含量變化), 토양(土壤)에서의 이동성(移動性) 등을 조사(調査)한바 다음과 같은 결과(結果)를 얻었다. 1. 규산질비료(珪酸質肥料) 20mg을 증류수50ml로 침출(浸出) 했을 때 용액(溶液)의 규산농도(珪酸濃度)는 10목이하(目以下), 20-35목(目), 100목이상(目以上) 입자(粒子)에 처하여 각각 0.3, 1.0, 3.2ppm 이었으며 1N-Na-acetate용액(溶液)으로 침출(浸出)했을 때의 농도(濃度)는 각각 24.5, 126.2, 225.5ppm 이었다. 2. 규산질비료(珪酸質肥料) 20mg을 첨가(添加)한 상양(上壤)20g을 증류수 50ml로 침출(浸出)했을 때 10목이하(目以下), 20-35목(目), 100목이상(目以上) 입자(粒子)의 규산질비료(珪酸質肥料)를 처리한 토양용액중(土壤溶液中)의 규산농도(珪酸濃度)는 규산(珪酸)을 첨가(添加)하지 않았을 때 보다 각각 0.25, 0.97, 3.28ppm 증가하였다. 3. 토양용액(土壤溶液)의 pH는 규산질비료(珪酸質肥料)의 첨가(添加) 여부와 관계(關係)없이 담수일수(湛水日數)와 함께 2~4주(週)까지는 상승(上昇)하고 그 후(後) 6~10주(週)까지 하강(下降)하였다. 이때 수용액중(水溶液中)의 규산농도(珪酸濃度)는 pH와 역상관(逆相關)을 냐타내었으나 담수(湛水) 6~10주이후(週以後)에는 pH와 관계(關係)없이 수용액중(水溶液中)의 규산농도(珪酸濃度)는 증가하였다. 4. 토양투하수(土壤透下水)의 분액별(分液別) 규산농도(珪酸濃度)는 규산질비료(珪酸質肥料)를 첨가(添加)하지 않았을 경우 투과수(透過水)의 양(量)이 0.88 pore volume에 달(達)했을 때 최고치(最高値)를 나타내었으며 20-35목(目), 100목이상(目以上)의 규산질비료(珪酸質肥料)를 첨가(添加)하였을 때에는 각 각 0.94, 1.03pore volume에서 최고농도(最高濃度)를 나타내었다. 5. 1.5pore volume의 증류수를 투하(透下)시킨 후(後) 토양(土壤) column의 부위별(部位別) 규산함량(珪酸含量)을 분석(分析)한 바 수용성(水溶性) 규산(珪酸) 함량(含量)은 6~9cm이하에서는 깊이에 관계없이 일정(一定)하나 그 위 부위(部位)에서는 위로 갈수록 낮은 함량(含量)을 나타내었다. 그러나 1N-Na-acetate 가용규산(可溶珪酸)은 이동(移動)되지 않고 규산(珪酸) 처리부위에 집적(集積)되어 있었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.405-408
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• 2007

Semi-solid Al-Zn-Mg alloys were produced using a cooling plate method in order to investigate the extrudability. Al melt was poured on cooling plate which was adjusted at $60^{\circ}$ with respect to the horizontal plane, and the melt was cooled by water circulation underneath. Obtained Semi-solid feedstock has globular microstructure but also contains considerable amount of gas pore. Due to the pore, tensile elongation of the semi-solid feedstock was very low and it doesn't show yield point phenomenon. Isothermal hot extrusion was carried out using at $400^{\circ}C$ with a ram speed of 1mm/sec and an extrusion ratio of 25:1. The extruded bar show noticeably improved tensile ductility and strength because pore volume fraction decreased from 5% to 0.8% after extrusion. Mechanical properties of the semi-solid extruded bar were compared with that of commercial casting alloy..

• 한국세라믹학회지
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• 제46권3호
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• pp.288-294
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• 2009

The platelet AlO(OH) nano colloids were prepared by hydrothermal reaction of the $\gamma-Al_2O_3$ obtained with dehydration of $\gamma$-AlO(OH) and dilute $CH_3COOH$ solution. In hydrothermal reaction process, reversible reaction was accompanied between $\gamma-Al_2O_3$ and AlO(OH), and hydrothermal reaction temperature, hydrothermal reaction time and $CH_3COOH$ concentration had an effect on the crystal structure, surface chemical property, surface area, pore characteristics and crystal morphology of the AlO(OH) nano colloid particles. In this study, it was investigated to the hydrothermal reaction condition of the AlO(OH) nano colloid for using catalyst support, heat resisting agent, adsorbents, binder, polishing agent and coating agent. The crystal structure, surface area, pore volume and pore size of the platelet AlO(OH) nano colloids were investigated by XRD, TEM, TG/DTA, FT-IR and $N_2$ BET method in liquid nitrogen temperature.

• 한국세라믹학회지
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• 제53권1호
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• pp.13-17
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• 2016

It is highlighted that increasing the adsorbent surface area on volumetric basis is very important in providing an easy access for gas molecules. Fine particles around $3{\mu}m$ of soft-burned dolomite kiln dust (SB-DKD) were hydrated to wet slurry samples by ball mill process and then placed in a chamber to use spray dryer method. Spherical granules with particle size distribution of $50{\sim}60{\mu}m$ were prepared under the experimental condition with or without addition of a pore-forming agent. The relationship between bead size of the pore-forming agent and size of SB-DKD particles is the most significant factor in preparation of spherical granules with a high porosity. Whereas addition of smaller beads than SB-DKD resulted in almost no change in the surface porosity of spherical granules, addition of larger beads than SB-DKD contributed to obtaining of the particles with both 15 times larger average pore volume and 1 order of magnitude larger porosity. It is considered that spherical granules with improved $N_2$ gas adsorption ability may also be utilized for other atmospheric gas adsorption.

• Carbon letters
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• 제12권3호
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• pp.171-176
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• 2011

Polyacrylonitrile-based carbon nanofibers (CNFs) containing Ti and Mn were prepared by electrospinning. The effect of metal content on the hydrogen storage capacity of the nanofibers was evaluated. The nanofibers containing Ti and Mn exhibited maximum hydrogen adsorption capacities of 1.6 and 1.1 wt%, respectively, at 303 K and 9 MPa. Toward the development of an improved hydrogen storage system, the optimum conditions for the production of metalized CNFs were investigated by characterizing the specific surface areas, pore volumes, sizes, and shapes of the fibers. According to the results of Brunauer-Emmett-Teller analysis, the activation of the CNFs using potassium hydroxide resulted in a large pore volume and specific surface area in the samples. This is attributable to the optimized pore structure of the metal-containing polyacrylonitrile-based electrospun CNFs, which may provide better sites for hydrogen adsorption than do current adsorbates.

• 한국세라믹학회지
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• 제32권3호
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• pp.385-393
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• 1995

Akali-resistant porous glass was prepared by phase separation in Na2O-B2O3-SiO2 system containing ZrO2 and MgO. ZrO2 was added for alkali-resistance and MgO for anti-cracking during leaching. Optimal content of ZrO2 for alkali-resistance was 7wt% and devitrification by heat treatment resulted from further addition. Pore size and pore volume were decreased and specific surface area was increased with ZrO2 addition due to depression in phase separation. Addition of 3mol% MgO to mother glass containing 7wt% ZrO2 was effective for anti-crack during leaching. In this case, with phase separation at 55$0^{\circ}C$ and 5$25^{\circ}C$ for 20 hrs. crack-free porous glasses could be prepared. The relation between pore size r and heat treatment time t at 55$0^{\circ}C$ was D=25.58＋18.16t. According to measurement of gas permeability, the mechanism of gas permeation was Knudsen flow. N2 and He permeability of porous glass which was prepared by heat treatment at 55$0^{\circ}C$ for 20 hrs. were 0.843$\times$10-7mol/$m^2$.s.Pa and 2.161$\times$10-7mol/$m^2$.s.Pa respectively.

• 한국환경농학회지
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• 제21권4호
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• pp.291-296
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• 2002

In this investigation we tried to investigate the effect of oxalic acid on the fate of native sulfate in Bt soil that contained a high kaolinitic clay by observing the distribution of two anions using soil column under the given competitive adsorption between displaced and displacing anions. To do this, the soil columns uniformly packed to a bulk density of 1.25 $g/cm^3$ with Cecil Bt soil were disected and analyzed the amounts of sulfate and oxalic acid both in solution and solid phases after flowing the designated pore volumes of oxalic acid The results showed that two sets of curves-nonlinear (> $10^3M$) and linear (> $10^3M$) curves where the solution of oxalic acid was not adiustet while the approaches to the plateau were slow when pH of oxalic acid was adjusted to 5. The cumulative amount of sulfate desorbed by successive addition of oxalic acid was nonlinearly approached to the plateau at the concentration of $10^3M$ or greater, indicating that the number of addition of oxalic acid increased with decreasing order of oxalic acid. However, the plateau did not obtain where the concentration of oxalic acid were less than $10^4M$, showing a linear increase. Therefore, we may conclude that the rate-limited desorption was involved as the concentration of oxalic acid decreased.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권5호
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• pp.45-52
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• 2014

Torrefaction and hydrothermal carbonization (HTC) are productive methods to reclaim energy from lignocellulosic biomass. The hydrophobic, homogenized, energy dense and carbon rich solid fuel can be obtain from torrefaction and hydrothermal carbonization. Dead leaves were carbonized in a stainless steel reactor of volume 200 ml with torrefaction ($250-270^{\circ}C$) for 120 minutes and hydrothermal carbonization ($200-250^{\circ}C$) for 30 minutes, with mass yield solid fuel ranging from 57-70% and energy content from 16.81MJ/kg to 22.01 MJ/kg compare to the biomass. The char produced from torrefaction process possess high energy content than hydrothermal carbonization. The highest energy yield of 89.96% was obtained by torrefaction at $250^{\circ}C$. The energy densification ratio fluctuated in between 1.15 to 1.30. On the basis of pore size distribution of the chars, the definition of the International Union of Pure and Applied Chemistry (IUPAC) was used as a classification standard. The pore diameter was ranging within 11.09-19 nm which play important role in water holding capacity in soil. Larger pores can hold water and provide passage for small pores. Therefore, it can be concluded that high pore size char can be obtained my HTC process and high energy content char of 22.01 MJ/Kg with 34.04% increase in energy can be obtain by torrefaction process.

• 한국재료학회지
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• 제9권4호
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• pp.362-367
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• 1999

We intended to make the activated carbon fibers which could separate, remove and recover the volatile organic compounds of benzene, toluene, acetone and methanol. Changing activation temperature and time, large specific surface area and narrow pore distribution could be obtained. The activated carbon fibers have large adsorption capacity and selectivility for those organic compounds. We characterized the adsorption capability of the activated carbon fibers for benzene, toluene, acetone and methanol by BET specific surface area and pore size and micropore volume measurements. In the result of activation, the maximum value of BET specific surface area of the fibers was $1100\m^2$/g at $800^{\circ}C$ for 60 minutes and $K_2$O was reduced actively in this condition. Their average pore size was 5.8~5.9$\AA$. The activated carbon fibers prepared in this work had high adsorption rate to saturation and the selectibility for the above organic compounds. The adsorbed amount of acetone and methanol(diameter of$ 4.3\AA$ and $4.4\AA$ respectively) which are smaller than micropore diameter in size was 43~49%, which was larger value than benzene and toluene(in the same diameter as $5.9\AA$).