• Coupled systems mechanics
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• v.8 no.1
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• pp.19-38
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• 2019

The influence of torsional rigidity of hinged flexible appendage on the linear dynamics of flexible spacecrafts with liquid on board was analyzed by considering the spacecraft's main body as a rigid tank, its flexible appendages as two elastically supported elastic beams, and the onboard liquid as an ideal liquid. The meniscus of the liquid free surface due to surface tension was considered. Using the Lagrangian of the spacecraft's main body (rigid tank), onboard liquid, and two beams (flexible appendages) in addition to assuming the system moved symmetrically, the coupled system frequency equations were obtained by applying the Rayleigh-Ritz method. The influence of the torsional rigidity of the flexible appendages on the spacecraft's coupled vibration characteristics was primary focus of investigation. It was found that coupled vibration modes especially that of appendage considerably changed with torsion spring parameter ${\kappa}_t$ of the flexible appendage. In addition, variation of the main body displacement with system parameters was investigated.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1167-1168
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• 2004

Polarized ultraviolet irradiation techniques have been developed recently to produce alignment of liquid crystals (LC). Because of the excellent thermal stability and the alignment ablility of polyimides, polyimides has attracted considerable research interest for the photoinduced alignment layer. Hasegawa and Taira confirmed homogeneous alignment of LC by the decompostion of a polyimide induced by lineraly ultra-violet polarized light. It was reported that ultraviolet visible absorption spectra of a polyimide alignment film showed a remarkable change upon irradiation. In this study, we synthesized phthalic polyimide and a naphthalenic polyimide in order to investigate the effect of the polyimide structure. Some difference in terms of the photo-induced molecular orientaion of liquid crystals were observed with the polyimide structure.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.777-782
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• 2014

This paper proposes an RGB to RGBY color conversion algorithm for liquid crystal display (LCD) using RGW pixel structure with two-field (yellow and blue) sequential driving method. The proposed algorithm preserves the hue and saturation of the original color by maintaining the RGB ratio, and it increases the luminance. The performance of the proposed RGBY conversion algorithm is verified using the MATLAB simulation with 24 images of Kodak lossless true color image suite. The simulation results of average color difference CIEDE2000 (${\delta}E^*_{00}$) and scaling factor are 0.99 and 1.89, respectively. These results indicate that the average brightness is increased 1.89 times compared to LCD using conventional RGB pixel structure, without increasing the power consumption and degrading the image quality.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.486-488
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• 2003

Some important properties of the liquid crystal molecules containing fluoro-isothiocyanated molecules have been studied using quantum chemical calculations and the results were correlated with respect to the structure of the molecules. Dielectric anisotropy, birefringence have been predicted for several unknown structures. The Maier-Meier, Vuks equation were used for the dielectric anisotropy and birefringence calculation. The results obtained by empirical approximation showed a good agreement with experiment ones.

• Journal of the Korean Chemical Society
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• v.16 no.5
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• pp.265-270
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• 1972

The aqueous solutions of aliphatic and aromatic hydrocarbons have been studied on the basis of the significant structure theory of liquid water proposed by Jhon, et al. The thermodynamic properties such as Helmholtz free energy, internal energy entropy, and heat capacity have been calculated. The results show good agreements with the experiments in the literature.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.395-400
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• 2014

We proposed a method for fast turn-off switching of a vertically-aligned liquid crystal cell by low-temperature curing of the polymer structure. We confirmed that the turn-off times of the fabricated cells were reduced significantly as the curing temperature was lowered to $-20^{\circ}C$. We accounted for the effect of low-temperature curing on the turn-off time by using a mathematical model and by observing images obtained via scanning electron microscopy. We also confirmed that low-temperature curing is more effective in reducing the response time when the device is operated at a low temperature.

• Journal of the Korean Wood Science and Technology
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• v.24 no.2
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• pp.81-93
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• 1996

To elucidate the structure of procyanidin in Korean red pine (Pinus densiflora S. et Z.), bark, the extractives were extracted with acetone-water mixture(7:3, v/v) from inner bark of Korean red pine. The extracts separated three fractions which were extracted by liquid-liquid extraction. The extracting solvents were chloroform and ethyl acetate and water. The part of ethylacetate soluble was chromatographed by liquid chromatography. The ethylacetate soluble portion yielded four natural procyanidin dimers, two known epicatechin-($4{\beta}{\rightarrow}6$)-catechin, catechin-($4{\alpha}{\rightarrow}8$)-catechin and two unknown catechin-($4{\beta}{\rightarrow}6$)-catechin and conformational isomer of epicatechin-($4{\alpha}{\rightarrow}6$)-catechin. The additional catechins was also isolated. The structures of these procyanidins were elucidated by their $^{13}C$-NMR spectra.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.125-128
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• 2007

The problem of water leakage due to damaging waterproof in concrete structure, causes the impediment in a long term and shortened the life span of durability. There are a lot of techniques for repair and reinforcement to improve using environment. However, the improper construction which is unconsidered various environmental conditions, could effect to increase the maintenance expenses. Therefore, this study will be compared and estimated the adhesion liquid and sheet integrate waterproofing material, as analyzing the existing problem. For those result, we would like to arrange the alterative plan for the long durability and user needs of concrete structure.

• Journal of the Korean Chemical Society
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• v.8 no.3
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• pp.125-127
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• 1964

Upon melting, a part of ethylene-chloride molecules in trans-form in the solid state changes into gauche-form. The partition function for the material was developed according to the significant structure theory of liquid proposed by H. Eyring and his co-workers, and the parameters $E_s$, ${\theta}$, $V_s$, and a, therein, are determined by the manner developed by Chang, et al. The molar volume, vapor pressure, vaporization entropy, critical point properties and surface tension of the liquid were calculated. The results are in good agreement with experimental values.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.140-146
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• 2016

Using density functional Theory, we studied local structure of liquid ethylene glycol and 1,3-propanediol. For both liquid, making intramolecular hydrogen bonding is not preferred, because relative energy between with and without intramolecular hydrogen bond is only -1.95kcal/mol, which is far less than intermolecular hydrogen bonding energy, about -7.5kcal/mol. Also, hydrogen bond induce polarization of hydroxyl group and make $2^{nd}$ hydrogen bond more stronger. This effect was small in intramolecular hydrogen bond of ethylene glycol. When considering energy per hydrogen bond, making only one intermolecular hydrogen bond for ethylene glycol pair is energetically favored, while two intermolecular hydrogen bond can be formed in 1,3-propanediol pair.