• Food Science and Biotechnology
• /
• 제16권2호
• /
• pp.183-186
• /
• 2007

The type of mixed gel network of $\kappa$-carrageenan/agar was determined by applying rheological principles. Apparent Young's modulus of the mixed gels was mathematically analyzed with (a) simply adding the moduli of two component gels, (b) phase-separated type's upper and lower bound models, (c) interpenetrating type's logarithmic model. The experimental data fitted the estimates from the operation (a). Whereas, as for the models (b), the experimental values in the agar-rich region fitted the estimates of the upper bound model, but in the $\kappa$-carrageenan-rich region slightly deviated from those of the lower bound model. It reflected an evidence of a phase-separated type, although it was not typical, that there must be data good-fit in the agar-rich and $\kappa$-carrageenan-rich regions with the upper and lower bound models, respectively. Experimental values disagreed with estimates of the model (c). Gel time was analyzed to evince the phase-separated type. As agar concentrations increased at a fixed amount of $\kappa$-carrageenan, gel time gradually decreased and then sharply increased and decreased again. The pattern of such change in gel time also represented a typical behavior of phase-separated type's mixed gels.

• 산업기술연구
• /
• 제27권A호
• /
• pp.149-155
• /
• 2007

The counter emf(electromotive forces) of a permanent magnet multi-phase brushless motor is generally a non-sinusoidal wave or a non-ideal trapezoid. So, conventional modeling using a sinusoidal wave or an ideal trapezoid counter emf can result in errors. In order to reduce modeling errors for simulation and analysis the properties of a multi-phase brushless AC motor, this paper proposes a phase variable model that is a mixed modeling technique using both Finite Element Analysis(FEA) based circuits and motor voltage equations. The phase model parameters including the counter emf voltage waveform are obtained by using of FEA, and the mixed modeling technique based on circuits and equations is used to implement a simulation model for multi-phase brushless AC motors with any counter emf voltage waveforms. Adequacy of the proposed model is established from the simulation and experimental results for a seven-phase brushless motor.

• Journal of applied mathematics & informatics
• /
• 제11권1_2호
• /
• pp.357-364
• /
• 2003

A fully discrete $H^1-mixed$ finite element approximation for the single-phase Stefan problem is introduced and the unique existence of the approximation is established. And some numerical experiments are given.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2008년도 추계학술대회 논문집
• /
• pp.230-233
• /
• 2008

The vanadium rich ash of petroleum coke can give a slagging problem during because of the high melting point of $V_2O_3$. For continuous removal of the slag, petroleum coke is often mixed with coal, and the viscosity of the mixed slag is an important property, determining the gasification temperature. The viscosities of the mixed slag from various mixing ratios of petroleum coke and a bituminous coal were investigated. When mixed with a crystalline coal slag, $T_{cv}$ was increased at a higher the coke content in the mixed feed. When the $V_2O_3$ concentration was greater than 4.5%, it was difficult to get accurate measurements of $T_{cv}$. The SEM/EDX analyses of the cooled slag revealed that the major crystalline phase was anorthite, and $T_{cv}$ should be related to the formation temperature of anorthite. The SEM/EDX analyses also showed that, at low concentrations of vanadium, part vanadium formed a crystalline phase with Al-Si-Ca-Fe, and the rest remained in the glassy phase, suggesting that vanadium existed as a slag component at the low viscosity region. At a high concentration, vanadium forms a phase with Ca, and the Ca-V phase was separated from the slag phase, and formed a layer above the slag. FeO in petroleum coke also played an important role determining viscosity: at high temperatures, increased FeO lowered the viscosity, but as it formed a spinel phase, the depletion of FeO in the slag resulted in a higher viscosity.

• 대한전자공학회논문지SD
• /
• 제39권8호
• /
• pp.24-33
• /
• 2002

혼성 신호 회로의 설계에 있어 저비용의 고효율 테스트 효율을 보장하기 위해 테스트의 노력은 계속되어 왔다. 특히 테스트를 고려한 BIST(built-in-self-test)설계 방법으로 발전해가고 있는 추세인데, 회로상에서 전체적인 테스트 용이도와 분석에 있어 보다 향상된 방법으로 접근할 수 있고 이러한 시스템에 대해 분석하는데 수월하게 할 수도 있다. 이 논문에서는 효과적인 테스트를 위한 방법을 위해 DC전압과 전압 위상에 대한 BIST를 구현하는 것을 제안하였다. 즉 정상적인 회로와 고장회로에서의 동작에서 전압과 위상의 차이를 검출하는 회로를 하드웨어상으로 구성함으로써 비용과 시간 등을 효과적으로 줄이는 방법을 제안하였다. 실험 결과에서는 기존의 BIST와 비교하여 향상된 것을 나타낸다.

• Food Science and Biotechnology
• /
• 제16권6호
• /
• pp.1069-1071
• /
• 2007

The frequency independent critical concentration (Cc) of xanthan and carob (X/C) mixed gel was determined based on the Winter-Chambon's theory. X/C mixed (X/C=1:1 ratio) gels were prepared from 0.1 to 1% of concentration. The linear viscoelastic properties, i.e., storage and loss modulus, of X/C mixed gel at $20^{\circ}C$ were measured by frequency sweep tests. The frequency independence of tangent function of phase angle (tan ${\delta}$) of X/C mixed gels was graphically determined from the intersection of the plot of phase angle against concentration at varied frequencies. The intersection (C=0.43%) was considered to be Cc of X/C mixed gel.

• Journal of applied mathematics & informatics
• /
• 제15권1_2호
• /
• pp.251-264
• /
• 2004

We introduce a semidiscrete mixed finite element approximation for the single-phase linear Stefan problem and show the unique existence of the approximation. And the optimal rate of convergence in $L^2$ and $H^1$ norms are derived.

• 한국전기전자재료학회논문지
• /
• 제31권1호
• /
• pp.29-33
• /
• 2018

Using a vanadium dioxide ($VO_2$) source, highly pure and amorphous vanadium oxide (VO) thin films were deposited using an e-beam evaporator at room temperature and high vacuum (<$10^{-7}$ Torr). Then, by controlling the post-annealing conditions such as $N_2:O_2$ pressure ratio and annealing time, we could easily synthesize a homogeneous $VO_2$ thin film and also mixed-phase VO thin films, including $VO_2$, $V_2O_5$, $V_3O_7$, $V_5O_9$, and $V_6O_{13}$. The crystallinity and phase of these were characterized by X-ray diffraction, and the surface morphology by FE-SEM. Moreover, the electrical properties and ethanol sensing measurements of the VO thin films were analyzed as a function of temperature. In general, mixed-phases as a self-doping effect have enhanced electrical properties, with a high carrier density and an enhanced response to ethanol. In summary, we developed an easy, scalable, and reproducible fabrication process for VO thin films that is a promising candidate for many potential electrical and optical applications.

• Elastomers and Composites
• /
• 제50권4호
• /
• pp.265-273
• /
• 2015

In this work, the emulsified asphalt with high phase stability and storage stability was prepared by using phase inversion emulsification and the surfactant mixed with cationic and nonionic surfactants. It was found that the asphalt together with Span 20, nonionic surfactant and DDA (Dimethyl Dodecyl Amine), cationic surfactant showed the most stable phase. The phase stability of the emulsified asphalt, therefore, was investigated through the particle size with mixed surfactant content, rheology behavior and Zeta potential value; the particle size decreased with the increase of the mixed surfactant content but the viscosity increased. The shear thinning behaviors and the Zeta potential value with 50 mV~60 mV were shown, which was found to be considered stable. In addition, SBR latex(Styrene-butadiene-rubber) and water dispersed Epoxy (EPD) were used to enhance the physical properties of the emulsified asphalt. The swelling and adhesion features of the emulsified asphalt were also studied with $CaCO_3$, Silica, and Montmorillonite (MMT). It was shown that the addition of SBR latex and MMT can be another way to improve the physical properties of the emulsified asphalt in that the lowest swelling feature was found.

• 한국광물학회지
• /
• 제10권2호
• /
• pp.97-104
• /
• 1997

Based on the method of determination for relative stability of each phase from the difference among the interaction parameters of the phases consisting the mixed layer, the types of interactions between layers were specified and interaction parameter between layers in ordered domain was analytically derived as a function parameter between layers in ordered domain was analytically derived as a function of not only temperature and mole fraction of layers but also ordering parameter. Interaction parameter between the different layers in ordered phase, L is as follows:{{{{ {L }_{1 } (X,Q,T)= { C} over { Q} -4(1-2Q) { L}^{2 } - { RT} over {2} ln { 1} over {2 } - { 2RT} over { { X}_{ s} } ln { { 4QX}`_{s } ^{2 } } over {(1- { X}_{s }- { QX}_{s })( { X}_{s }- {QX }_{s } ) } }}}}L2 is the interaction parameter between ordered and disordered phase in domain and is the mole fraction of the domain which represent the infinite length of mixed layer mineral and Q and C are the reaction progress parameter and arbitrary constant, respectively. This equation was used for the I/S mixed layer clay minerals to infer the relative stability of R1 type I/S mixed layer in the temperature range from 373K to 450K. The result of calculation suggest that, owing to the decrease in interaction parameter with increasing temperature. The interaction parameter decreases more rapidly with decreasing mole fraction of smectite in domain, which is consistent with the fact that the probability of finding the series smectite layer is lo in the domain with small mole fraction of smectite layers in natural system.