• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.203-204
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• 2008

Using various surfactants, multi-walled carbon nanotube (MWNT) was dispersed in organic solvent, isopropylalcohol(IPA). To refine the MWNT and give the functional group, MWNT was treated with sulfuric acid/nitric acid(v/v=3/1). The cationic, nonionic and anionic surfactants were used as MWNT dispersion agents in the organic solvent. Dispersion effect of various surfactants was observed by optical microscope and HR-TEM. Surface resistivities of MWNT dispersions were measured after coating on PET film. MWNT was dispersed well by poly vinyl pyrrolidone(PVP), nonionic surfactant.

• Journal of Advanced Navigation Technology
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• v.22 no.3
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• pp.240-245
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• 2018

A flexible dispersion-managed link configuration is proposed by using single-mode fibers (SMFs) and dispersion-compensating fibers (DCFs) with irregular dispersion coefficients and lengths over all fiber spans for compensating of WDM channels distortion due to the group velocity dispersion and nonlinear effects of optical fibers. The flexibility of link is enabled by artificially distributing of these fibers based on the dispersion coefficients of DCFs in each half transmission section. The simultaneous ascending and descending (AD) distribution of the DCF's coefficients before and after the optical phase conjugator, respectively, best compensates the distorted wavelength division multiplexed signals in the optical link. Therefore, to improve the compensation effect of the distorted WDM channels, AD distribution is needed to choice regardless of fiber lengths and the residual dispersion per span and fiber's dispersion coefficients.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.6
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• pp.767-777
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• 1999

In the coastal region air flow changes due to the abrupt change of surface temperature between land and sea. So a numerical simulation for atmospheric flow fields must be considered the correct fields of sea surface temperature(SST). In this study, we used variables such as latent heat flux, sensible heat flux, short and long wave radiation of ocean and atmosphere which exchanged across the sea surface between atmosphere and ocean model. We found that this consideration simulated the more precise SST fields by comparing with those of the observated results. Simulated horizontal SST differences in season were 2.5~4$^{\circ}C$. Therefore we simulated the more precise atmospheric flow fields and the movement and dispersion of the pollutants with the Lagrangian particle dispersion model. In the daytime dispersion pattern of the pollutants emitted from ship sources moved toward inland, in the night time moved toward sea by land/sea breeze criculation. But air pollutants dispersion can be affected by inland topography, especially Yangsan and coastal area because of nocturnal wind speed decrease.

• Journal of the Optical Society of Korea
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• v.12 no.4
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• pp.244-248
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• 2008

We have evaluated the performance of strain-chirped fiber Bragg grating (FBG) based tunable dispersion compensator in a 40 Gb/s transmission link. In our proposed compensator, the value of dispersion could be changed from -353 ps/nm to -962 ps/nm by adjusting the rotation angle of the metal beam on which the FBG was mounted. In order to evaluate the effect of ripples in reflectivity and variations in passband of the FBG based dispersion compensator, transmission performance has been measured with our tunable dispersion compensator. Error-free transmission of a 40 Gb/s non-return-to-zero (NRZ) signal over conventional single-mode fiber (SMF) was achieved.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.2
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• pp.230-237
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• 2024

Dispersion munitions are often equipped with dispersive submunitions used to scatter bombs over a wide area, and one of the types of dispersive submunitions is the Magnus rotor, commonly referred to as a self-rotating flying body. The Magnus rotor is designed to be dispered over a wide area by utilizing the principle of the Magnus effect through self-rotation, and has various trajectories depending on the initial conditions from the mother dispersion munition. In this paper, an index to evaluate the dispersion uniformity of footprint of the dispersive submunition is presented and the dispersion uniformity according to various initial release conditions is evaluated, and it is getting larger with high incidence angle and get max value at certain initial angular velocity.

• Proceedings of the Materials Research Society of Korea Conference
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• 1993.05a
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• pp.141-142
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• 1993

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.1
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• pp.195-201
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• 2019

Long caisson breakwaters can improve the structural safety of a caisson due to the wave dispersion effect which reduces the average wave force acting on one caisson. However, in order to make long caissons, there are many manufacturing and construction limitations. Recently, interlocking caisson systems, which are to form a long caisson by interlocking individual caissons with adjacent caissons, have been much attention. In the present study, a interlocking caisson system with shear-keys was proposed and the wave dispersion effect according to the shear-key was evaluated analytically. As a result, (1) Because of the asymmetric shape of the interlocking caisson, the structure behavior and the wave dispersion effect of one are also asymmetric. (2) The wave dispersion effect is more influenced by the distribution and characteristics of wave acting on each caisson rather than the shape of the shear-key such as shear angle, height, shear length ratio. (3) The interlocking caisson breakwater is almost the same behavior and wave dispersion effect as a fully integrated breakwater.

• Asia Marketing Journal
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• v.15 no.3
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• pp.53-77
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• 2013

As advertising and promotions are categorized as operating expenses, managers tend to reduce marketing budget to improve their short term profitability. Gauging the value and accountability of marketing spending is therefore considered as a major research priority in marketing. To respond this call, recent studies have documented that financial market reacts positively to a firm's marketing activity or marketing related outcomes such as brand equity and customer satisfaction. However, prior studies focus on the relation of marketing variable and financial market variables. This study suggests a channel about how marketing activity increases firm valuation. Specifically, we propose that a firm's marketing activity increases the level of the firm's product market information and thereby the dispersion in financial analysts' earnings forecasts decreases. With less uncertainty about the firm's future prospect, the firm's managers and shareholders have less information asymmetry, which reduces the firm's cost of capital and thereby increases the valuation of the firm. To our knowledge, this is the first paper to examine how informational benefits can mediate the effect of marketing activity on firm value. To test whether marketing activity contributes to increase in firm value by mitigating information asymmetry, this study employs a longitudinal data which contains 12,824 firm-year observations with 2,337 distinct firms from 1981 to 2006. Firm value is measured by Tobin's Q and one-year-ahead buy-and-hold abnormal return (BHAR). Following prior literature, dispersion in analysts' earnings forecasts is used as a proxy for the information gap between management and shareholders. For model specification, to identify mediating effect, the three-step regression approach is adopted. All models are estimated using Markov chain Monte Carlo (MCMC) methods to test the statistical significance of the mediating effect. The analysis shows that marketing intensity has a significant negative relationship with dispersion in analysts' earnings forecasts. After including the mediator variable about analyst dispersion, the effect of marketing intensity on firm value drops from 1.199 (p < .01) to 1.130 (p < .01) in Tobin's Q model and the same effect drops from .192 (p < .01) to .188 (p < .01) in BHAR model. The results suggest that analysts' forecast dispersion partially accounts for the positive effect of marketing on firm valuation. Additionally, the same analysis was conducted with an alternative dependent variable (forecast accuracy) and a marketing metric (advertising intensity). The analysis supports the robustness of the main results. In sum, the results provide empirical evidence that marketing activity can increase shareholder value by mitigating problem of information asymmetry in the capital market. The findings have important implications for managers. First, managers should be cognizant of the role of marketing activity in providing information to the financial market as well as to the consumer market. Thus, managers should take into account investors' reaction when they design marketing communication messages for reducing the cost of capital. Second, this study shows a channel on how marketing creates shareholder value and highlights the accountability of marketing. In addition to the direct impact of marketing on firm value, an indirect channel by reducing information asymmetry should be considered. Potentially, marketing managers can justify their spending from the perspective of increasing long-term shareholder value.

• Textile Coloration and Finishing
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• v.26 no.4
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• pp.339-346
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• 2014

To give a positive effect on dispersion behavior of high performance fibers $Vectran^{(R)}$ in water with reference to wet-laid nonwoven technology, 9 kinds of sulfonate type anionic surfactants were chosen to study. After dispersion experiment, the number and the area occupied by fibers in each sample were counted and figured to calculate the index of dispersion in conjunction with quadrat analysis. Similar tendency was observed in the results of two experiments. The sample without addition of any surfactant resulted in the most aggregated dispersion behavior. As the length of alkyl group attached to sulfonate increases, the sample shows more dispersed behavior. The sample with the surfactant having the aryl group and the longer alkyl group shows the most dispersed behavior and it can be seen with the naked eye as well.

• Journal of Powder Materials
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• v.25 no.5
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• pp.395-401
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• 2018

The improvement of dispersion stability for the primary polishing slurry in a CMP process is achieved to prevent defects produced by agglomeration of the slurry. The dispersion properties are analyzed according to the physical characteristics of each silica sol sample. Further, the difference in the dispersion stability is confirmed as the surfactant content. The dispersibility results measured by Zeta potential suggest that the dispersion properties depend on the content and size of the abrasive in the primary polishing slurry. Moreover, the optimum ratio for high dispersion stability is confirmed as the addition content of the surfactant. Based on the aforementioned results, the long-term stability of each slurry is analyzed. Turbiscan analysis demonstrates that the agglomeration occurs depending on the increasing amount of surfactant. As a result, we demonstrate that the increased particle size and the decreased content of silica improve the dispersion stability and long-term stability.