• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.654-659
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• 1996

Amorphous $TiO_2$ thin films were deposited on silicon substrates by the RF magnetron sputtering under various conditions, and studied by the spectroscopic ellipsometry (SE). To determine the optical constants as a function of photon energy and also to depth-profile the as-deposited $TiO_2$ thin films, we analyzed the ellipsometric spectra using the effective medium approximation and the dispersion equations. Especially, we improved the modeling accuracy by selectively using either the Sellmeier or the Forouhi and Bloomer dispersion equation in different energy regions.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.555-559
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• 2015

Coherence length (time) is a key parameter in many classical and quantum optical applications. Two interferometers – Michelson and Young’s double-slit – are used to characterize the temporal coherence of single photons emitted from single terrylene molecules. For quantitative analysis, a dispersion-related distortion in the interference pattern of a Michelson interferometer is carefully corrected by a simple dispersion compensation. Additionally, it has been demonstrated that Young’s interferometer can be used in temporal coherence studies at the single photon level with high accuracy. The pros and cons of the two systems are discussed. The measured coherence lengths in the two systems are consistent with one another under the self-interference interpretations.

• 연구논문집
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• s.28
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• pp.39-47
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• 1998

Industrial electrostatic precipitation is a very complex process, which involves multiple-way interaction between the electric field, the fluid flow, and the particulate motion. This paper describes a strongly coupled calculation procedure for the rigorous computation of particle dynamics during electrostatic precipitation. The turbulent gas flow and the particle motion under electrostatic forces are calculated by using the commercial computational fluid dynamics (CFD) package FLUENT linked to a finite-volume solver for the electric field and ion charge. Particle charge is determined from both local electrical conditions and the cell residence time which the particle has experienced through its path. Particle charge density and the particle velocity are averaged in a control volume to use Lagrangian information of the particle motion in calculating the gas and electric fields. The turbulent particulate transport and the effects of particulate space charge on the electrical current flow are investigated. The calculated results for poly-dispersed particles are compared with those for mono-dispersed particles, and significant differences are demonstrated.

• Journal of the Optical Society of Korea
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• v.19 no.2
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• pp.130-135
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• 2015

Based on the extended nonlinear Schr$\ddot{o}$dinger equation, the influences of the filter effect on pulse splitting in a passively mode-locked erbium-doped fiber laser with positive dispersion cavity are investigated theoretically. Numerical results show that, as the bandwidth of the spectral filter decreases, the nonlinear chirp appended to the pulse increases under the combined action of the filter effect of the super-Gaussian spectral filter and the self-phase modulation effect. On further decreasing the bandwidth, the wave breaking of the pulse takes place. In addition, by varying the pump power of the laser or the profile of the spectral filter, the influences of the filter effect on pulse splitting also change accordingly.

• The Korean Journal of Ceramics
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• v.5 no.2
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• pp.115-118
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• 1999

Carbon composites with $MoSi_2$ dispersion were prepared by hot-pressing at $1700^{\circ}C$ under 30 MPa for 1 h using polysilazance as binding material. The composites consisted of C, $Mo_{4.8}Si_3C_{0.6}$ and SiC. Bulk density and porosity of the carbon composites with 10 vol% $MoSi_2$ was 1.8g.$\textrm{cm}^{-3}$ and 34%, respectively. This composite was oxidized about 0.05mm from the surface of the carbon composite after oxidation test at $1500^{\circ}C$ for 10h in air. Formation of the $SiO_2$ glass layer was observed by SEM. When this composite suffered damage in the coating layer, it had hardly farther oxidation because of its self-repairing property. The composite prepared in this study indicated good oxidation resistance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.81-82
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• 2006

The purposes of the present study are to produce a high thermal efficient of oil-based nanofluids which can be used as ultra-high voltage transformer oil, and to investigate their thermal and physical properties under static and dynamic conditions. Three kinds of nanofluids are prepared by dispersing $Al_2O_3$ or AlN nanoparticles in transformer oil. The thermal conductivities of the nanoparticles-oil mixtures increase with temperature, particle volume concentration and thermal conductivity of solid particle itself. It was quite important to eliminate $H_2O$ as byproducts of esterification and excess oleic acid which did not form stable chemical bonds with powder surface to get high dispersion stability.

• Journal of Integrative Natural Science
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• v.12 no.3
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• pp.78-84
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• 2019

In many cases, the quality of a product is determined by several correlated quality variables. Control charts have been used for a long time widely to control the production process and to quickly detect the assignable causes that may produce any deterioration in the quality of a product. Numerical switching performances of multivariate cumulative sum control chart for simultaneous monitoring all components in the dispersion matrix ${\Sigma}$ under multivariate normal process $N_p({\underline{\mu}},{\Sigma})$ are considered. Numerical performances were evaluated for various shifts of the values of variances and/or correlation coefficients in ${\Sigma}$. Our computational results show that if one wants to quick detect the small shifts in a process, CUSUM control chart with small reference value k is more efficient than large k in terms of average run length (ARL), average time to signal (ATS), average number of switches (ANSW).

• Coupled systems mechanics
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• v.10 no.2
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• pp.185-198
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• 2021

An analytical model is consider to scrutinize axisymmetric wave propagation in multiferroic hollow cylinder with rotating and initial stressed forces, where a piezomagnetic (PM) material layer is bonded to a piezoelectric (PE) cylinder together by Linear elastic materials with voids. Both distinct material combos are taken into account. Three displacement potential functions are introduced to uncouple the equations of motion, electric and magnetic induction. The numerical calculations are carried out for the non-dimensional frequency by fixing wave number and thickness. The arrived outputs are plotted as the dispersion curves for different layers. The results obtained in this paper can offer significance to the application of PE/PM composite hollow cylinder via LEMV and CFRP layers for the acoustic wave and microwave technologies.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.275-282
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• 2010

The laboratory column experiments were used to transport of metal elements by infiltration-related dispersion and/or diffusion in mine tailing of the Guryong gold mine. The mine tailing shows the neutral pH (for a pore water) and contains quartz, chlorite, pyrite and calcite. Both a non-reactive solute ($Cl^-$ of 100 mg $L^{-1}$) and a reactive solute (1N HCl), were injected continuously through columns. The breakthrough curve in the non-reactive experiment reached at a maximum under 1.5 pore volumes (PV). The longitudinal dispersion (0.607 cm) and hydrodynamic dispersion coefficient ($1.96{\times}10^{-7}cm^{2}sec^{-1}$) were calculated by the slope. In the reactive experiment, the plateau curve was appeared in the pH values of 5.3, 4.5 and 1.7. The releases of metal elements such as Fe, Mn, Al, Cu, Zn, Pb, and Cd were observed to be related to the pH buffering. High concentrations of Mn, Cd and Zn were observed at the first pH plateau (4 PV and pH 5.3), whereas Fe, Cu, Al and Pb were released as the pH decreased to 4.0 or less. The resulting order of metals mobility, based on the effluent water, is Mn=Cd>Zn>Cu>Fe>Al>Pb.

• Journal of Information Technology Applications and Management
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• v.21 no.4_spc
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• pp.381-401
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• 2014

This study proposes the accurate economic effect (employment inducement coefficient, hiring inducement coefficient, index of the sensitivity of dispersion, index of the power of dispersion, and ratio of value added) of Korea software industry by analyzing the inter-industry relation using the modified inter-industry table. Some previous studies related to the inter-industry analysis were reviewed and the key problems were identified. First, in the current inter-industry table publishedby the Bank of Korea, the output of software industry includes not only the output of pure software industry (package software and IT services) but also the output of non-software industry due to the misclassification of the industry. This causes the output to become bigger than the actual output of the software industry. Second, during rewriting the inter-industry table, the output is changing. The inter-industry table is the table in the form of rows and columns, which records the transactions of goods and services among industries which are required to continue the activities of each industry. Accordingly, if only an output of a specific industry is changed, the reliability of the table would be degraded because the table is prepared based on the relations with other industries. This possibly causes the economic effect coefficient to degrade reliability, over or under estimated. This study tries to correct these problems to get the more accurate economic effect of the software industry. First, to get the output of the pure software section only, the data from the Korea Electronics Association(KEA) was used in the inter-industry table. Second, to prevent the difference in the outputs during rewriting the inter-industry table, the difference between the output in the current inter-industry table and the output from KEA data was identified and then it was defined as the non-software section output for the analysis. The following results were obtained: The pure software section's economic effect coefficient was lower than the coefficient of non-software section. It comes from differenceof data to Bank of Korea and KEA. This study hasa signification from accurate economic effect of Korea software industry.