• Title/Summary/Keyword: 비표면적

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The Influence of Grain Size of Sandy Soil on the Strength and Stiffness of Silicate-Grouted Soil. (사질토의 입경이 물유리계 약액주입권결토에 강도 및 강성에 미치는 영향)

  • Jeong, Hyeong-Sik;Cheon, Byeong-Sik;Ryu, Jae-Il
    • Geotechnical Engineering
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    • v.4 no.4
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    • pp.29-38
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    • 1988
  • One of the main objectives of researches for the chemical grouting is to assess the changes in soil properties caused by injection of chemical grout. Especially the changes in the strength properties of soils, such as elastic modulus, shear modulus of ground due to injection of chemical grout has drawn our attention. Since the specific surface changes with variation in the grain size of sandy soil, the influence of grain size of sandy toil on the strength and stiffness of silicate-grouted soil was investicated in this study by earring out uniaxial and triaxial compression tests. It was found that the strength and stiffness of grouted soil increased as the grain size of sandy soil decreases, the possibility of estimating the strength of grouted soil was confirmed through the study of relationship between specific surface of sandy soil and the strength of chemical gel.

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Poly(vinylidene fluoride)-based Porous Carbon Nanofibers (폴리비닐리덴 풀루오라이드로부터 제조된 다공성 탄소나노섬유)

  • Chung, H.J.;Jo, S.M.;Kim, D.Y.;Chin, B.D.;Lee, D.W.
    • Journal of Hydrogen and New Energy
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    • v.16 no.4
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    • pp.334-342
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    • 2005
  • 200-300 nm 직경을 지닌 폴리비닐리덴 플루오라이드 초극세 섬유를 전기방사법으로 제조하였다. 이들을 불응화시킨 후, $800-1800^{\circ}C$ 온도에서 탄화시켜 PVdF 계 탄소나노 섬유를 제조하여 구조 및 기공분석을 하였다. 이들은 20-30 nm 크기의 탄소입자로 이루어져 있으며 탄소나노입자는 1 nm이하의 슬릿형 나노기공을 지니고 있었다. 탄화온도가 증가함에 따라 비표면적은 $1500^{\circ}C$에서 $414\;m^2/g$로 감소하였으나, $1800^{\circ}C$에서는 $1300\;m^2/g$로 급격히 다시 증가하였으며 1 nm 이하의 나노기공만을 지닌 탄소섬유가 얻어졌다. 비표면적 및 기공특성과 수소저장특성을 관계를 조사하기 위하여 Magnetic Syspension Balance(MSB)를 사용한 중량법으로 평가한 이들의 수소저장능은 0.04-0.4wt%이었다.

A Study of Mixing Characteristics for Cosmetic Pine Powder (화장품용 미분체 혼합공정에서의 분산특성 연구)

  • 이종옥;송건응
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.19 no.1
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    • pp.85-107
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    • 1993
  • The cosmetic fine powders were mixed with variation of mixing time(5) in the mixers (ribbon mixer, powder mixer, micropulverizer and fine impact mill). The powders were nixed with small amount of ferric oxide. as tracer. The mixed powders ere measured the particle size distribution, specific surface area and surface color with mixing time (s). The color variation, particle size distribution and specific surface area of the mixed powder exist a relationship with mining time(s) that can be expressed as mathematical equations to show the degree of the mixing of the powder mixture. The linear velocity of the impellar tip is the main factor contributing to he mixing efficiency of the mixers un this study. According to the linear velocity, he mixers used are devieded as convection mixing (ribbon mixer), sclera mixing powder mixer) and diffusion mixing (micropulverizer/fine impact mill).

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Photocatalytic Properties of TiO2 According to Manufacturing Method (제조방법에 따른 TiO2의 광촉매 특성 분석)

  • Lee, Hong Joo;Park, Yu Gang;Lee, Seung Hwan;Park, Jung Hoon
    • Korean Chemical Engineering Research
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    • v.56 no.2
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    • pp.156-161
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    • 2018
  • $TiO_2$ photocatalyst powders were prepared by chlorination method and sol-gel method. Specific surface area and crystalline (i.e., anatase and rutile) of the catalyst varied depending on manufacture conditions and method. TTIP-sol photocatalyst had higher methylene blue (MB) decomposition characteristics than photocatalyst from chlorination method and TBOT-sol. MB removal efficiency from aqueous solution with TTIP-sol photocatalyst was over 90%. Experimental results showed that the $TiO_2$ photocatalyst with a single anatase phase and a large specific surface area had high decomposition characteristics of organic materials.

Manufacture of Activated Carbon based on Solid Residue after Lignin Pyrolysis (리그닌 열분해 잔류고형물을 원료로 한 활성탄의 제조)

  • Lee, Jong-Jib;Yoon, Sung-Wook;Lee, Byung-Hak
    • Journal of Korean Society of Environmental Engineers
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    • v.22 no.1
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    • pp.133-139
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    • 2000
  • In this study, activated carbon was prepared from solid residue after lignin pyrolysis by using zinc chloride as an activation agent. The steam activation method was adopted to manufacture activated carbon from solid residue after lignin pyrolysis. The effect of process operation variables such as activation temperature, activation time and mass of activation agent added to char on the pore structure and specific surface area of the activated carbon was investigated. Activated carbon with high surface area and well-developed pore structure could be prepared, when solid residue after lignin pyrolysis was mixed with zinc chloride of 300 wt% and then the mixture was activated for 1 hour at $1000^{\circ}C$ in a stream of nitrogen.

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Geophysical Implications for Configurational Entropy and Cube Counting Fractal Dimension of Porous Networks of Geological Medium: Insights from Random Packing Simulations (지질매체 공극 구조에 대한 구성 엔트로피와 상자집계 프랙탈 차원의 지구물리학적 의미 및 응용: 무작위 패킹 시뮬레이션 연구)

  • Lee, Bum-Han;Lee, Sung-Keun
    • Journal of the Mineralogical Society of Korea
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    • v.23 no.4
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    • pp.367-375
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    • 2010
  • Understanding the interactions between earth materials and fluids is essential for studying the diverse geological processes in the Earth's surface and interior. In order to better understand the interactions between earth materials and fluids, we explore the effect of specific surface area and porosity on structural parameters of pore structures. We obtained 3D pore structures, using random packing simulations of porous media composed of single sized spheres with varying the particle size and porosity, and then we analyzed configurational entropy for 2D cross sections of porous media and cube counting fractal dimension for 3D porous networks. The results of the configurational entropy analysis show that the entropy length decreases from 0.8 to 0.2 with increasing specific surface area from 2.4 to $8.3mm^2/mm^3$, and the maximum configurational entropy increases from 0.94 to 0.99 with increasing porosity from 0.33 to 0.46. On the basis of the strong correlation between the liquid volume fraction (i.e., porosity) and configurational entropy, we suggest that elastic properties and viscosity of mantle melts can be expressed using configurational entropy. The results of the cube counting fractal dimension analysis show that cube counting fractal dimension increases with increasing porosity at constant specific surface area, and increases from 2.65 to 2.98 with increasing specific surface area from 2.4 to $8.3mm^2/mm^3$. On the basis of the strong correlation among cube counting fractal dimension, specific surface area, and porosity, we suggest that seismic wave attenuation and structural disorder in fluid-rock-melt composites can be described using cube counting fractal dimension.

Strategy for the improvement of the crop monitoring using remote sensing techniques (원격탐사기법을 활용한 작물재배면적 파악의 개선 전략)

  • Seo, Dong-Jo
    • Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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    • 2009.04a
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    • pp.271-272
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    • 2009
  • 우리나라의 농업통계조사방법은 과거의 조사방법을 그대로 사용하고 있어 비표본오차발생 가능성이 높은 상황이다. 따라서 작물재배면적의 통계조사에 위성영상을 활용함으로써 조사 및 통계자료의 제공에 효율성 및 정확성을 높이는 것이 필요하다. 이를 위해서 UN, 미국, 캐나다, 유럽 등을 중심으로 위성영상을 사용한 경지면적조사, 재배면적조사, 작황예측분석 등 농업통계의 생산 사례를 살펴보았다. 이후 국내 활용동향을 분석하여 원격탐사기법을 활용한 작물재배면적 파악의 개선전략을 제시하였다.

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Effect of Specific Surface Area of Activated Carbon Fiber on Harmful Gas Adsorption and Electrochemical Responses (활성탄소섬유의 비표면적에 따른 유해가스 흡착 및 전기화학적 감응 특성)

  • Kang, Jin Kyun;Chung, Yong Sik;Bai, Byong Chol;Ryu, Ji Hyun
    • Journal of Adhesion and Interface
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    • v.21 no.2
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    • pp.51-57
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    • 2020
  • Recently, there has been growing interest in the study of removal of harmful and hazardous pollutants emitted by industrial activities. In this study, we have developed porous activated carbon fibers prepared by a water vapor activation method and analyzed the adsorptions of the harmful gases with electrochemical responses of activated carbon fibers. To control the uniformity of pore structures, active reaction areas, and active sites, the reaction conditions of activation temperatures were varied from 750 to 850 ℃ with the predetermined reaction time intervals (30 to 240 min). The SO2 and NO gas adsorptions of activated carbon fibers prepared by various reaction conditions were analyzed and monitored by electrochemical sensor responses. In particular, the activated carbon fibers prepared at the reaction temperature of 850 ℃ and time of 45 min showed the highest specific surface area (1,041.9 ㎡/g) and pore characteristics (0.42 ㎤/g), and excellent adsorption capabilities of SO2 (1.061 mg/g) and NO (1.210 mg/g) gases, respectively.

Preparation of Nano-Sized Tin Oxide Powder by Spray Pyrolysis Process (분무열분해(噴霧熱分解) 공정(工程)에 의한 주석(朱錫) 산화물(酸化物) 나노 분말(粉末) 제조(製造))

  • Yu, Jae-Keun;Cha, Kwang-Yong;Kim, Myung-Choun;Han, Joung-Su;Jang, Jae-Bum;Lee, Yong-Hwa;Kim, Dong-Hee
    • Resources Recycling
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    • v.17 no.6
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    • pp.79-88
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    • 2008
  • This study is the previous stage for the mass production technology development of the nano-sized tin oxide powder by the recycling of the wasted tin metal, and nano-sized tin oxide powder with the average particle size below 50 nm is prepared from the tin chloride solution by the spray pyrolysis process. As the reaction temperature increases from 800 to 850, the average particle size of the generated powder increases from 20 to 30 nm. As the reaction temperature increases to 900, the droplet type is composed of the particles with the average size of the 30 nm. while the average size of the independent particles increases up to $80{\sim}100$ nm and the surface microstructure becomes more solid. Until $900^{\circ}C$, as the reaction temperature increases, the XRD peak intensity increases, while the specific surface area decreases. When the reaction temperature increases to 950, most of the powder appears with the independent type and the average particle size decrease down to 70 nm. The XRD peak intensity greatly decreases and the specific surface area increases almost twice.

Formation of Porous Boehmite for Supporting Enzyme Catalyst (효소촉매 담지체용 다공성 베마이트 제조)

  • Yem, Hye Suk;Kim, Ki Do;Jun, Chang Lim;Kim, Hee Taik
    • Applied Chemistry for Engineering
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    • v.17 no.2
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    • pp.188-193
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    • 2006
  • Synthesis of Boehmite particles were performed through the precipitation of aluminium nitrate ($Al_{3}(NO_{3})_3{\cdot}9H_{2}O$) with ammonia water ($NH_{4}OH$) by changing solution pH, mixing procedure, temperature, and feeding flux. The influence of the synthesis condition, which affected on the pH range of the Boehmite formation, particle morphology and pore property, was investigated. The Boehmite particles were formed in the reaction solution of pH 7.5~9. The particles prepared by P2jet type which maintained the pH uniformly during the precipitation resulted in homogeneous particles and pores because of the constant concentration of the reacted ion in the solution. It was resulted in the improvement of the specific surface area and pore volume of the particle at the same time. With the increasing of temperature and the decreasing of the feeding flux, it was occurred the large specific surface area and pore volume. Also it was presented the fibrillar shaped particles upper $60^{\circ}C$ of the reaction temperature. In this study, the optimal condition of the porous Boehmite was in P2jet type with $90^{\circ}C$ of reaction temperature and 2.5 mL/min of the feeding flux. At this time, the specific surface area, pore volume, and average pore size was $385.46m^2/g$, 1.0252 mL/g, 10 nm, respectively.