• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1142-1146
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• 2004

The synthetic route and physical properties for three-ring derivatives, trans-2,3,2',3'-tetrafluoro-4-alkyl-4'-(4-alkyl-cyclohexyl)-biphenyl and 4-alkyl-cyclohexane carboxylic acid 2,3,2',3',4'-pentafluoro-biphenyl-4-yl ester are presented. They exhibit broad range nematic phases exceeding 30K and low viscosity of nematic liquid crystal mixtures containing these materials. Their viscosity is compared with that of homologues with a lateral isothiocyanate group and show large negative dielectric anisotropies. The threshold voltage $V_{th}$ was low enough to be operated at a driving voltage of 5V. Our novel LC compounds are suitable materials for the improvement of dielectric anisotropy of vertical align liquid crystal displays (VA-LDCs).

• Nuclear Engineering and Technology
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• v.41 no.7
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• pp.979-988
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• 2009

Tensioned metastable fluids provide a powerful means for low-cost, efficient detection of a wide range of nuclear particles with spectroscopic capabilities. Past work in this field has relied on one-component liquids. Pure liquids may provide very good detection capability in some aspects, such as low thresholds or large radiation interaction cross sections, but it is rare to find a liquid that is a perfect candidate on both counts. It was hypothesized that liquid mixtures could offer optimal benefits and present more options for advancement. However, not much is known about radiation-induced thermal-hydraulics involving destabilization of mixtures of tensioned metastable fluids. This paper presents results of experiments that assess key thermophysical properties of liquid mixtures governing fast neutron radiation-induced cavitation in liquid mixtures. Experiments were conducted by placing liquid mixtures of various proportions in tension metastable states using Purdue's centrifugally-tensioned metastable fluid detector (CTMFD) apparatus. Liquids chosen for this study covered a good representation of both thermal and fast neutron interaction cross sections, a range of cavitation onset thresholds and a range of thermophysical properties. Experiments were devised to measure the effective liquid mixture viscosity and surface tension. Neutron-induced tension metastability thresholds were found to vary non-linearly with mixture concentration; these thresholds varied linearly with surface tension and inversely with mixture vapor pressure (on a semi-log scale), and no visible trend with mixture viscosity nor with latent heat of vaporization.

• Journal of the Korean Magnetic Resonance Society
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• v.16 no.2
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• pp.122-132
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• 2012

The effects of the sample viscosity and volume on the convective flows induced by temperature gradient in PGSE-NMR self-diffusion measurements at high temperature have been investigated. The experimental results showed that the viscosity of the liquid sample strongly affects the magnitude of the convective flows as well as the diffusion coefficient itself. It was also found that the convective flows increase as the sample volume increase.

• Macromolecular Research
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• v.17 no.5
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• pp.313-318
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• 2009

The side chain liquid crystal triblock copolymers (TBCs), which underwent phase transitions below their decomposition temperature, were prepared by copolymerization of poly(n-butyl acrylate) and a comonomer containing the mesogenic azobenzene group. The physical properties of TBCs in the distinctive transition temperature ranges were investigated in terms of the liquid crystal (LC) content in the copolymers. The phase transition temperatures traced optically, thermally and rheologically were well coincided one another and clearly exhibited the phase transition of smectic-nematic-isotropic with increasing temperature. In the smectic phase, increasing temperature made the liquid crystal system more elastic, but viscosity (${\eta}'$) remained almost constant. In the nematic phase, increasing temperature abruptly decreased ${\eta}'$ and G', ultimately leading to isotropic phase. Both smectic and nematic phases exhibited Bingham viscosity behavior but the former gave much greater yield stress at the same LC content.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.6
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• pp.868-874
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• 2002

A high-impulse, low-power, digital microthruster has been developed using low-boiling-temperature liquid propellant with high-viscosity fluid plug. The viscous fiction force of the fluid plug increases the blast pressure and the low-boiling-temperature liquid propellant is intended to reduce input power consumption. The three-layer microthruster has been fabricated by surface micromachining as well as bulk micromachining in the size of 7$\times$13$\times$1.5㎣. A digital output impulse bit of 6.4$\times$10$^{-8}$ Nsec has been obtained from the fabricated microthruster using perfluoro normal hexane (FC72) propellant and oil plug, resulting in about ten times increase of the impulse bit using one hundredth electrical input energy compared to the conventional multiple-shot microthruster.

• Journal of ILASS-Korea
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• v.6 no.2
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• pp.29-36
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• 2001

Vortices terminating at free surface have been investigated extensively. however. are focused on surface parallel vortices and little has been known about surface normal vortex or columnar vortex. Visualized experimental results utilizing LlF technique are discussed for the purpose of characterization of columnar vortex interacting with a clean and a contaminated free surfaces and a solid body interface in the present investigation. The results reveal that surface tension changes due to surface contamination although bulk viscosity remains constant and eventually the behavior of a columnar vortex interacting with a contaminated free surface and a solid body interface are totally different from the clean free surface case.

• Nuclear Engineering and Technology
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• v.47 no.1
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• pp.126-134
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• 2015

A simple Couette flow velocity profile with an appropriate correlation for the free terminal rise velocity of a single bubble in a quiescent liquid can produce reliable results for the trajectories of small spherical air bubbles in a low-viscosity liquid (water) provided the liquid remains under uniform shear flow. Comparison of the model adopted in this paper with published results has been accomplished. Based on this study it has also been found that the lift coefficient in water is higher than its typical value in a high-viscosity liquid and therefore a modified correlation for the lift coefficient in a uniform shear flow of water within the regime of the $E\ddot{o}tv\ddot{o}s$ number $0.305{\leq}Eo{\leq}1.22$ is also presented.

• Journal of the Semiconductor & Display Technology
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• v.12 no.3
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• pp.1-6
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• 2013

In many technical fields including electronics and display manufacturing processes, properties of coating liquids could be greatly enhanced by adding nanopowders and it requires efficient mixing techniques to achieve uniform dispersion of nanoparticles in liquids. This paper presents the three-dimensional CFD simulations on the flowfields of a highly viscous liquid in the large scale industrial mixer of impeller type. The effects of several important design and operation parameters such as impeller geometry, rotational speed, and degree of liquid viscosity are investigated to appreciate the mixing performance by examining the computational results for flow pattern of rotationally stirred liquid of high viscosity in the mixer.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.156-169
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• 1997

This study was designed to evaluate the influences of evaporation of liquid of dental cements by drying during long term using. Zinc phosphate cement, polycarboxylate cement, and glass ionomer cement were used, and evaluated the properties as follows; consistency, setting time, film thickness, solubility, and compressive strength according to the ADA specification. The specimens of control group were made by mixing the newly opened liquid using the powder-liquid ratio recommended by the manufacturer, and the specimens of ES groups were made by mixing the 10% evaporated liquid by drying with the powder-liquid ratio recommeded by the manufacturer, and the specimens of EM group were made by mixing the 10% evaporated liquid with the powder-liquid ratio modified for standard consistency. The following conclusions were drawn ; 1. The viscosity of mixture of all kinds of cements were increased by the evaporation of liquid, especially the viscosity of glass ionomer cement were influenced significantly. 2. The amount of liquid should be increased to get a standard consistency at the using of evaporated liquid of cement, the most significant increase of liquid amount was required on Ketac-Cem. 3. The setting times were increased at both cases of mixing of evaporated liquid with powder - liquid ratio recommended by manufacturer or modifided through consistency test. 4. At an experimental group of mixing of the evaporated liquid with powder-liquid ratio recommended by manufacturer, solubility was decreased and film thickness was increased. 5. By the result of evaporation of cement liquid, the compressive strength of polycarboxylate cement was increased slightly and it of glass ionomer cement was increased, however, by the increase of amount of liquid to be possible to manipulate the compressive strength were decreased.

• Cement
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• s.32
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• pp.33-38
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• 1969