• 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.

• Analytical Science and Technology
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• v.28 no.1
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• pp.33-39
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• 2015

CdS-QD particles are a nano-sized semiconducting crystal that emits light. Their optical properties show great potential in many areas of applications such as disease-diagnostic reagents, optical technologies, media industries and solar cells. The wavelength of emitting light depends on the particle size and thus the quality control of CdS-QD particle requires accurate determination of the size distribution. In this study, CdS-QD particles were synthesized by a simple ${\gamma}$-ray irradiation method. As a particle stabilizer polyvinyl pyrrolidone (PVP) were added. In order to determine the size and size distribution of the CdS-QD particles, sedimentation field-flow fractionation (SdFFF) was employed. Effects of carious parameters including the the flow rate, external field strength, and field programming conditions were investigated to optimize SdFFF for analysis of CdS-QD particles. The Transmission electron microscopy (TEM) analysis show the primary single particle size was ~4 nm, TEM images indicate that the primarty particles were aggregated to form secondary particles having the mean size of about 159 nm. As the concentration of the stabilizer increases, the particle size tends to decrease. Mean size determined by SdFFF, TEM, and dynamic light scattering (DLS) were 126, 159, and 152 nm, respectively. Results showed SdFFF may become a useful tool for determination of the size and its distribution of various types of inorganic particles.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.104-109
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• 2001

The time to measure the size distribution using Condensation Nuclei Counter(CNC) and Differential Mobility Analyzer(DMA) can be shortened by classifying particles ramping the DMA voltage exponentially and continuously. In measurement, particles sampled at different time are mixed together going through sampling tube and CNC. Because the size distribution is inversed by using detector responses to sampling time intervals in this accelerated method, the mixing effects give inversion errors to the size distribution. The mixing effects can be considered by appling the transfer function with mixing effects to the data inversion. The inversion considering this effects gives birth to the size distribution shifted to the opposite direction of the size scanning.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.981-987
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• 2002

Monodispersed colloidal silica was prepared by Stober process. We have synthesized monodispersed colloidal silica of carious sizes (100 nm, 200 nm, 300 nm) by controlling volume ratios of TEOS(Tetraethylorthosilicate), $NH_4OH$, Ethanol and D. I. water. Shape and monodispersity of the synthesized colloidal particles were observed by Scanning Electron Microscopy(SEM) and laser light scattering particle analyzer. Self-assembled monolayer of monodispersed colloids was achieved by dipping Si substrate into a well-dispersed silica suspension. It was determined that uniformity and spatial extent of the self-assemble monolayer of monodispersed colloids are significantly influenced by the experimental parameters such as concentration, pH and surface tension of the colloidal suspension. We have observed a hexagonally well-ordered packing colloidal monolayer in a relatively large area (1.5 mm ${\times}$ 1.5 mm) as confirmed by SEM.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.2
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• pp.45-49
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• 2006

Electrochemical hydrogenation/dehydrogenation properties were studied for a single particle of a Mm-based(Mm : minh metal) hydrogen storage alloy($MmNi_{3.55}Co_{0.75}Mn_{0.4}Al_{0.3}$) for fuel cell and Ni-MH batteries. A carbon fiber microelectrode was manipulated to make electrical contact with an alloy particle, and the potential-step experiment was carried out to determine the apparent chemical diffusion coefficient of hydrogen atom($D_{app}$) in the alloy. Since the alloy particle we used here was a dense, conductive sphere, the spherical diffusion model was employed for data analysis. $D_{app}$ was found to vary the order between $10^{-9}\;and\;10^{-10}[cm^2/s]$ over the course of hydrogenation and dehydrogenation process. Compared with the conventional composite film electrodes, the single particle measurements using the microelectrode gave more detailed, true information about the hydrogen storage alloy.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.238.1-238.1
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• 2011

본 연구에서는 non-contact deposition method의 일환인 ESD (electroctatic deposition)의 박막공정을 이용하여 Conductive layer 위에 Gold nanoparticles 및 Silver nanoparticles 등 organic/inorganic nano particle conductive ink system의 단분산 2D 박막을 제조를 연구하였다. ESD head를 통해 여러가지 organic / inorganic nano particle conductive ink system을 Deposition하였으며 분산도가 높고 균일한 단분산의 2차원 박막 구조를 얻을 수 있었으며, 전도성 PEDOT과의 Hybridization을 통해 균일상의 표면 Morphology를 갖는 고 전도성 투명 필름을 제작하였다. ESD technique를 이용하는 박막공정 기술은 나노입자 및 나노구조물의 박막화 패턴화를 포함하는 새로운 Deposition 기술로써 이를 응용하여 금속 나노입자의 2차원의 패턴화된 박막 구현을 통해 유기반도체 및 전자소자에의 응용성을 증거할 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.3
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• pp.194-200
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• 2009

Suspension of a single solid particle in a channel flow with a constant pressure gradient is studied numerically. The interaction of a circular particle with a surrounding Newtonian fluid is formulated using a combined formulation. Numerical results are presented using two dimensionless variables: the sedimentation Reynolds number and the generalized Froude number. From the present results, it has been shown that a solid particle is suspended at a smaller generalized Froude number as the viscosity of the surrounding fluid increases. The time taken for equilibrium position is found to be smaller as fluid viscosity increases when both : the sedimentation Reynolds number and the generalized Froude number are the same while, at the same situation, the dimensionless time taken for equilibrium position is to be nearly the same regardless of fluid viscosity when a dimensionless time variable is introduced

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2003.08a
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• pp.222-226
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• 2003

대부분의 경우에 하구의 미세-점착성 퇴적물은 보통 무기성 광물과 유기물 및 생화학물의 혼합체이며, 광물 입자들은 주로 점토와 실트로 구성되어 있다. 이러한 혼합체의 침식특성은 사질성 퇴적물과는 달리 입자간의 응집현상에 의한 의해 크게 영향을 받으며, 응집강도는 광물질 구성, 입경분포, 유기물 함량 등으로 묘사되는 퇴적물 자체의 물리ㆍ화학적 기본특성에 따라 크게 변화하고 (Mea, 1986), 특히 저면 퇴적물의 침식 여부는 흐름 전단응력에 의한 저면퇴적물의 저항력 즉, 저면전단강도의 상대적 크기의 차이에 좌우되므로, 그 침식 특성은 저면전단강도 흑은 저면밀도로 묘사되는 저면특성에 따라 크게 변화한다(황규남 등, 2003). 또한 각 해역마다 저면 퇴적물은 퇴적물 공급원, 수동학적 조건, 생태학적 조건 등이 모두 다른 상태에서 형성된 퇴적층이므로, 저면 퇴적물의 기본특성 및 저면특성은 "site- specific" 한 성격을 갖는다. (중략)

• Journal of the Korean Society of Radiology
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• v.10 no.3
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• pp.153-159
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• 2016

This study investigated relationship between secondary electrons produced from single gold nanoparticle as a result of its interaction with radiation and particle size and incidence energy, provided basic data related to the dose enhancement effect based on gold nanoparticles. Monte Carlo simulation was applied by using MCNPX MC code, 50, 100, 150 kV and 6, 15 MV x-ray energy was used. In a water phantom, single gold nanoparticles that are 30, 50, 70, 90, and 110 nm in diameter were placed and the tally volume was designated at every 10 nm. Difference in electrons produced from gold nanoparticles was normalized based on absence of nanoparticle. When the X ray energy decreased and the diameter of gold particles increased, more electrons were produced. When the energy was lower, in the linear formula related to nanoparticle size and electron production, the gradient was higher. And, in comparison to the MV X-ray, at kV X-ray, significantly more electrons were produced. This study can be used as data to understand the dose enhancement effect based on gold nanoparticles, and further research related to various materials that dose enhancement including gold nanoparticles needs to be conducted.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.9-10
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• 2014