• 한국식품과학회지
• /
• 제23권6호
• /
• pp.759-763
• /
• 1991

게살과 구조적으로 유사한 대두단백 섬유는 dope를 방사하여 얻은 것으로, 대두단백의 dispersion이나 dope의 성질에 의존한다. 대두단백섬유의 출발물질인 대두단백의 dispersion과 dope의 동적 물성을 측정함으로서 그들의 점탄성을 조사하였다. 단백질 농도가 증가할때 dispersion이나 dope모두 단백질간의 상호반응이 일어났다. Dispersion에 알칼리 용액을 넣은 dope는 고분자 중합물질에 상호연결된 특성을 나타내었다. 반면에 dispersion에서는 무정형 중합물질의 특성이 나타났다. Dispersion에 대한 화학변형이 동적물성에 미치는 영향도 관찰하였다.

• 한국재료학회지
• /
• 제29권4호
• /
• pp.221-227
• /
• 2019

This study examines the role of the nano- and micro-particle ratio in dispersion stability and mechanical properties of composite resins for SLA(stereolithography) 3D printing technology. VTES(vinyltriethoxysilane)-coated $ZrO_2$ ceramic particles with different nano- and micro-particle ratios are prepared by a hydrolysis and condensation reaction and then dispersed in commercial photopolymer (High-temp) based on interpenetrating networks(IPNs). The coating characteristics of VTES-coated $ZrO_2$ particles are observed by FE-TEM and FT-IR. The rheological properties of VTES-coated $ZrO_2/High-temp$ composite solution with different particle ratios are investigated by rheometer, and the dispersion properties of the composite solution are confirmed by relaxation NMR and Turbiscan. The mechanical properties of 3D-printed objects are measured by a tensile test and nanoindenter. To investigate the aggregation and dispersion properties of VTES-coated $ZrO_2$ ceramic particles with different particle ratios, we observe the cross-sectional images of 3D printed objects using FE-SEM. The 3D printed objects of the composite solution with nano-particles of 80 % demonstrate improved mechanical characteristics.

• 한국환경과학회지
• /
• 제11권9호
• /
• pp.907-914
• /
• 2002

Various Eulerian-Lagrangian models for the one-dimensional longitudinal dispersion equation in nonuniform flow were studied comparatively. In the models studied, the transport equation was decoupled into two component parts by the operator-splitting approach; one part is governing advection and the other is governing dispersion. The advection equation has been solved by using the method of characteristics following fluid particles along the characteristic line and the results were interpolated onto an Eulerian grid on which the dispersion equation was solved by Crank-Nicholson type finite difference method. In the solution of the advection equation, Lagrange fifth, cubic spline, Hermite third and fifth interpolating polynomials were tested by numerical experiment and theoretical error analysis. Among these, Hermite interpolating polynomials are generally superior to Lagrange and cubic spline interpolating polynomials in reducing both dissipation and dispersion errors.

• 대한기계학회논문집A
• /
• 제31권4호
• /
• pp.483-489
• /
• 2007

We have investigated quantitative measurement techniques of the degree of dispersion of single-walled carbon nanotubes (SWNTs). SWNTs were suspended in aqueous media using a sodium dodecyl sulfate (SDS) surfactant. SWNTs with different dispersion states were prepared by controlling the intensity and time of sonication and centrifugation. The laser spectroscopic techniques were employed to characterize the dispersion state; i.e., raman fluorescence and absorption spectroscopic techniques. Raman spectroscopy has been used to probe the dispersion and aggregation state of SWNTs in solution. Individually suspended SWNTs show increased fluorescence peaks and decreased roping peaks at a raman shift 267 $cm^{-1}$ compared with the samples containing bundles of SWNTs. The ultraviolet-visible-near infrared (UV-vis-NIR) absorption spectrum of decanted supernatant samples show sharp van Hove singularity peaks

• 대한수학회보
• /
• 제47권6호
• /
• pp.1225-1234
• /
• 2010

Numerical solutions for the fractional differential dispersion equations with nonlinear forcing terms are considered. The backward Euler finite difference scheme is applied in order to obtain numerical solutions for the equation. Existence and stability of the approximate solutions are carried out by using the right shifted Grunwald formula for the fractional derivative term in the spatial direction. Error estimate of order $O({\Delta}x+{\Delta}t)$ is obtained in the discrete $L_2$ norm. The method is applied to a linear fractional dispersion equations in order to see the theoretical order of convergence. Numerical results for a nonlinear problem show that the numerical solution approach the solution of classical diffusion equation as fractional order approaches 2.

• 한국환경과학회지
• /
• 제8권5호
• /
• pp.555-558
• /
• 1999

A sea/land breeze circulation system and a regional scale circulation system are formed at a region which has complex terrain around coastal area and affect to the dispersion and advection of air pollutants. Therefore, it is important that atmospheric circulation model should be well designed for the simulation of regional dispersion of air pollutants. For this, Local Circulation Model, LCM which has an ability of high resolution is used. To verify the propriety of a LCM, we compared the simulation result of LCM with an exact solution of a linear theory over a simple topography. Since they presented almost the same value and pattern of a vertical velocity at the level of 1 km, we had a reliance of a LCM. For the prediction of dispersion and advection of air pollutants, the wind filed should be calculated with high accuracy. A numerical simulation using LCM will provide more accurate results over a complex terrain around coastal area.

• Korean Journal of Hydrosciences
• /
• 제5권
• /
• pp.85-97
• /
• 1994

A hybrid finite difference method for the longitudinal dispersion equation, which is based on combining the Holly-Preissmann scheme with fifth-degree Hermite interpolating polynomial and the generalized Crank-Nicholson scheme, is described and comparatively evaluated with other characteristics-based numerical methods. Longitudinal dispersion of an instantaneously-loaded pollutant source is simulated, and computational results are compared with the exact solution. The present method is free from wiggles regardless of the Courant number, and exactly reproduces the location of the peak concentration. Overall accuracy of the computation increases for smaller value of the weighting factor, $\theta$of the model. Larger values of $\theta$ overestimates the peak concentration. Smaller Courant number yields better accuracy, in general, but the sensitivity is very low, especially when the value of $\theta$ is small. From comparisons with the hybrid method using cubic interpolating polynomial and with splitoperator methods, the present method shows the best performance in reproducing the exact solution as the advection becomes more dominant.

• 대한수학회지
• /
• 제58권4호
• /
• pp.835-847
• /
• 2021

We study behavior of numerical solutions for a nonlinear eigenvalue problem on ℝⁿ that is reduced from a dispersion managed nonlinear Schrödinger equation. The solution operator of the free Schrödinger equation in the eigenvalue problem is implemented via the finite difference scheme, and the primary nonlinear eigenvalue problem is numerically solved via Picard iteration. Through numerical simulations, the results known only theoretically, for example the number of eigenpairs for one dimensional problem, are verified. Furthermore several new characteristics of the eigenpairs, including the existence of eigenpairs inherent in zero average dispersion two dimensional problem, are observed and analyzed.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2021년도 봄 학술논문 발표대회
• /
• pp.201-202
• /
• 2021

Currently, the domestic construction industry is trying to expand the range of building materials due to overload of growth. In particular, several studies are being conducted to make up for the weakness of building materials by solving problems such as reduction of tensile strength and brittle behavior of concrete. Among them, efforts to maximize the use of carbon nanotubes (CNT) that has excellent mechanical and electrical conductivity properties are continuing. However, CNT is hydrophobic and have a strong Van der Waals force between particles, making it difficult to obtain an effective dispersion state. Therefore, in this study, various kinds of surfactants like DOC (Sodium Deoxycholate), PVP (Polyvinylpyrrolidone), and PCE (Polycarboxylate ester) were added to improve the dispersibility of CNT, and analyzed the changes in the properties of the cement paste mixed with them.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.1851-1856
• /
• 2003

A new Lagrangian stochastic dispersion model is developed by combining the GLM(generalized Langevin model) and the elliptic relaxation method. Under the physically plausible assumptions a simple analytical solution of elliptic relaxation is obtained. To compare the performance of our model with other model, the statistics of particle velocity as well as concentration are investigated. Numerical simulation results show good agreement with available experimental data.