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Stability of O/W Emulsions Prepared from Winsor Systems-1 (Winsor계에서 제조된 O/W 에멀젼의 안정성 연구-1)

  • Cho, Wan-Goo
    • Applied Chemistry for Engineering
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    • v.9 no.2
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    • pp.261-267
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    • 1998
  • We have investigated the stability of macroemulsions of AOT prepared from Winsor systems. The emulsion system was prepared from heptane+aqueous NaCl+AOT. As the concentration of NaCl increases, the stability of the emulsion increases, reaches a maximum, and then decreases. At low salt concentration the creaming occurred due to density difference of oil and aqueous phases. We developed a model for the creaming. Behavior of the emulsions containing low salt could be described very well by the model, however, at high salt concentration the electrostatic repulsion decreased due to screening and droplets started to attract each other and the stability of the emulsion decreased.

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Influence of Water on Compression Characteristic of Decomposed Granite Soil Based on Single Particle Crushing Strength (단입자파쇄강도에 기초한 화강풍화토의 압축특성에 미치는 수분의 영향)

  • Ham, Tae-Gew;Kim, Uk-Gie
    • Journal of the Korean Geotechnical Society
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    • v.24 no.11
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    • pp.101-109
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    • 2008
  • In order to investigate the influence of the water on compression characteristic of decomposed granite soils, a single particle crushing test and one-dimensional compression tests were carried out on three decomposed granite soils and Silica sand. The initial fracture strength for single particle reduced and variability of the strength increases due to weakening by existing water. Moreover, it was recognized that one-dimensional compression characteristic was related to the initial fracture strength characteristic, and the initial fracture strength also has the effect of weathering.

The Late Cretaceous Emplacement Age of Masan Hornblende-Biotite Granite (마산 각섬석-흑운모 화강암의 연령: 후기 백악기 정치연령)

  • Lee, Tae-Ho;Park, Kye-Hun;Kim, Jeongmin;Kim, Myoung Jung
    • The Journal of the Petrological Society of Korea
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    • v.26 no.1
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    • pp.1-11
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    • 2017
  • We have dated the K-Ar, Ar-Ar and U-Pb ages of the Masan hornblende-biotite granite in the southern Cretaceous Gyeongsang basin to constrain its emplacement age. The ~108 Ma hornblende K-Ar age obtained in the study is similar to the previously reported Rb-Sr age. However, the single grain total fusion $^{40}Ar/^{39}Ar$ dating on hornblende failed to yield statistically meaningful ages because the isotopic system was open during its alteration. Thus the hornblende K-Ar age in the study is also unlikely to be reliable. The single grain total fusion $^{40}Ar/^{39}Ar$ dating on biotite yielded an average age of $75.8{\pm}3.0Ma$. Apart from scattered data in the range of ~45-75 Ma, the average age increased to ~80 Ma. The SHRIMP and LA-MC-ICPMS U-Pb isotopic compositions of zircon from the Masan hornblende-biotite granite yielded its emplacement age as $87.6{\pm}2.7Ma$ and $86.8{\pm}0.4Ma$, respectively. It is thus likely that the ~80 Ma $^{40}Ar/^{39}Ar$ age of biotite might reflect the cooling age of Masan hornblende-biotite granite or the thermal influences from later intense igneous activities in the Gyeongsang basin.

A Study on the Compression Characteristics of Decomposed Granite Soil Based on Single Particle Crushing Property (단입자파쇄특성에 기초한 화강풍화토의 압축특성에 관한 연구)

  • 함태규;조용성;김유성
    • Journal of the Korean Geotechnical Society
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    • v.20 no.8
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    • pp.103-111
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    • 2004
  • There are some problems in evaluating the bearing capacity of decomposed granite soils by general equations on account of their inherent compressibility and crushability. In order to investigate this kind of the engineering characteristics on decomposed granite soils in detail, it is necessary to how the micro property of the single particle composing the granite soils, and then the relevance to the macro characteristics of the soils has to be cleared. The reason why the single particle properties are not studied is first the difficulty to find out some regulating parameters, and secondly little understanding of its significance. Furthermore, the water in the decomposed granite soils accelerates the particle crushing. Consequently, increasing of compressibility and decreasing of shear strength would occur. Actually, when the ground settlement is a big issue in the embanked ground using the decomposed granite soils, the sensitive change of compressibility due to the change of water content in the ground becomes conspicuous. In this study, the single particle strength characteristics are studied and microscopic particle shape analyses are performed. In addition the compressibility of the decomposed granite soils and water content effect on the compressibility are analysed based on the test results.

연소중 미분탄입자의 발광 스펙트럼 분석에 의한 온도와 겉보기 방사율 측정

  • 최상민
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.4
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    • pp.892-898
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    • 1990
  • 본 연구에서는 소형 연소로에서 단입자 석탄화염을 형성하고 스펙트럼 분석기 를 통하여 순간적으로 입자 발광스펙트럼을 획득하고 이를 컴퓨터에서 분석하는 장치 를 구성하였다. 입자로부터의 발광신호(luminous signature)를 측정하여 연소과정에 서의 복사거동을 파악하여 이로부터 광학적 온도측정을 하는 방법을 보고하다. 본 논문에서는 미분탄 입자 화염의 in-situ측정에 의한 스펙트로스코피 방법을 보고하는 데에 중점이 있으므로 전형적인 화염의 스펙트럼에 의한 자료분석 방법을 제시하였고 화염조건에 따른 결과치의 변화상황은 별도로 보고한다.

A numerical model for combustion process of single coal particle in hot gas (고온 유동장 내 석탄 단입자 연소과정의 특성화를 위한 수치적 연구)

  • Niu, Xiaoyang;Lee, Hookyung;Choi, Sangmin
    • 한국연소학회:학술대회논문집
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    • pp.301-304
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    • 2015
  • With the experiment observation of single particle combustion, this model is built for the numerical analysis of the process. It's about the single coal particle combustion process under different conditions with reasonable assumptions. The model can express the mass, radius, density, temperature changing with different particle sizes, oxygen concentration and gas temperature. It also includes the flame sizes change in different condition and the diffusion of each species. The result shows the characters of the combustion.

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A Study on the Nuclear Structure through the Multipurpose Coincidence Measurement System Development ( I ) - The Electromagnetic Properties of the Gamma Transitions in $^{75}As$- (다목적 동시측정 장치 개발에 의한 원자핵 구조 연구(I) - $^{75}As$의 감마 전이에 대한 전자기적 특성 -)

  • Chung, Won-Mo;Chung, Kap-Soo;Joo, Koan-Sik;Na, Sang-Kyun;Hwang, Han-Yull
    • Journal of Radiation Protection and Research
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    • v.18 no.1
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    • pp.53-61
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    • 1993
  • The gamma-gamma coincidence measurements and angular correlation measurement associated with the electron capture of $^{75}Se$ have been carried to understand the structure for the odd nuclei $^{75}As$ with two HPGe detectors. As a result, we could determined the band structure of 5/2 state to be of 1/2 [310] band which is based on $f_{5/2}$ proton state. Also we obtained the multipole admixture in the state of 279.5keV by using the mixing ratios of $121.1{\sim}279.5keV$ cascade. Subsequently, it is determined that 25.56% electric quadrupole transition is involved in the state of 279.5keV.

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Preparation Of Composite particles with planarized $SiO_2$ Particles (평탄면을 갖는 $SiO_2$미립자의 제조와 이를 이용한 $SiO_2/TiO_2$복합입자의 제조)

  • 신달식;김광수;이옥섭;이성호
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.25 no.1
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    • pp.37-54
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    • 1999
  • Planarized SiO$_2$ particles were prepared by two-step reduction method of making much smaller particles, micron-sized ones, to improve spreadability, adherence, and smoothness. Various pigments known as flaky extender usually have terrace layers on their surfaces, but SiO$_2$ Particles in this study exhibit a smooth surface structure. These single SiO$_2$ particles were used for core particles to prepare the composite particles coated with ultra fine TiO$_2$ particles by a homogeneous precipitation method. The thickness and the morphology of the deposited TiO$_2$ layer could be altered by adjusting the reactant concentrations, reaction time and temperature. The characteristics of SiO$_2$/TiO$_2$composite in the field of color cosmetics is to give a UV-cut effect and to enhance the chroma of human skin color, one of optical properties.

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