• Korean Journal of Optics and Photonics
• /
• v.22 no.2
• /
• pp.108-113
• /
• 2011

In this paper, we propose the complex differential diagram to classify surface plasmon waveguide modes with single interface. To date, surface plasmon waveguide modes are classified using the sign change of the group velocity in the dispersion relation that describes the interrelations between the real wavenumber of the propagation direction and the photon energy. The surface plasmon waveguide modes have the wavenumbers of the direction perpendicular to that in which the wave propagates as well as of the propagation direction, so it is necessary to classify the modes using all of these wavenumbers. The complex differential diagram is a graphical representation with variables of the difference between the real component and the imaginary component of the wavenumber. Using this diagram, the specific mode classification is possible, and it is easy to comprehensively analyze the wavenumber as the function of the photon energy.

• Journal of Welding and Joining
• /
• v.15 no.5
• /
• pp.134-143
• /
• 1997

The formation of thick alloyed layer with high Si content have been investigated on the surface of Al alloy (A5083) plate by PTA process with Si powder. Hardening characteristics and wear resistance of alloyed layer was examined in relation to the microstructure of alloyed layer. Thick hardened layer in mm-order thickness on the surface of A5083 plate can be formed by PTA process with wide range of process condition by using Si powder as alloying element because of eutectic reaction of Al-Si binary alloy. High temperature and rapid solidification rate of molten pool, which are features of PTA process, enable the formation of high Si content alloyed layer with uniform distribution of fine primary Si paticle. High plasma arc current was beneficial to make the alloyed layer with smooth surface appearance in wide range of powder feeding rate, because enough volume of molten pool was necessary make alloyed layer. Uniform dispersion of fine primary Si particle with about 30${\mu}{\textrm}{m}$ in particle size can be obtained in layer with Si content ranging from 30 to 50 mass %. Hardness of alloyed layer increased with increasing Si content, but increasing rate of hardness differed with macrostructure of alloyed layer. Wear resistance of alloyed layer depended on $V_{si}$(volume fraction of primary Si) and was remarkably improved to two times of base metal at 20-30% $V_{si}$ without cracking, but no more improvement was obtained at larger $V_{si}$.

• Journal of Family Resource Management and Policy Review
• /
• v.12 no.3
• /
• pp.119-145
• /
• 2008

This study was designed to verify the influence of mothers on their young adults in pro-environmental consuming consciousness and behavior. The compiled data are based on the responses of questionnaires from 278 young adults who reside in Seoul, Korea. The data were analyzed by frequency, standard deviation, mean, unitary dispersion, rank revolution analysis, analysis of variance (ANOVA), and multiple regression analysis by SPSS 14.0K for Windows. This study has discovered the following: First. A mother's pro-environmental consuming behavior is one of the most important factors significantly influencing a young adult's consciousness and behavior. Second. A friendly and positive consciousness about the environment enhances pro-environmental consuming behavior. A close inter-relationship exists between consciousness and behavior. However, some significant discrepancy was found between pro-environmental consuming consciousness and pro-environmental consuming behavior; that is, the level of pro-environmental consciousness was higher than the level of pro-environmental behavior. Third. Sensitivity to environmental information influenced pro-environmental consumption consciousness and behavior. Female students are more concerned about and sensitive to environmental matters than are male students. Fourth. Among the subordinate dependent variables, recycling behavior is most influenced by independent variables. Among the pro-environmental consuming behavior sector, a mother's disposal behavior exerts the most influence on the young adult's behavior. In the results of this study, it is pointed out that it is absolutely necessary fur young adults to bring up their practice level of pro-environmental purchase and consuming behaviors, and it is advised that appropriate and relevant education programs should be developed.

• Bulletin of the Korean Space Science Society
• /
• 2009.10a
• /
• pp.36.2-36.2
• /
• 2009

We present GALEX (Galaxy Evolution Explorer) far (FUV) and near (NUV) ultraviolet imaging of 34 nearby early-type galaxies from the SAURON representative sample of 48 E/S0 galaxies, all of which have ground-based optical imaging from the MDM Observatory. The surface brightness profiles of nine galaxies (~26 per cent) show regions with blue UV-optical colours suggesting recent star formation. Five of these (~15 per cent) show blue integrated UV-optical colours that set them aside in the NUV integrated colour-magnitude relation. These are objects with either exceptionally intense and localised NUV fluxes or blue UV-optical colours throughout. They also have other properties confirming they have had recent star formation, in particular Hbeta absorption higher than expected for a quiescent population and a higher CO detection rate. This suggests that residual star formation is more common in early-type galaxies than we are used to believe. NUV-blue galaxies are generally drawn from the lower stellar velocity dispersion (sigma_e <200 km/s) and thus lower dynamical mass part of the sample. We have also constructed the first UV Fundamental Planes and show that NUV blue galaxies bias the slopes and increase the scatters. If they are eliminated the fits get closer to expectations from the virial theorem. Although our analysis is based on a limited sample, it seems that a dominant fraction of the tilt and scatter of the UV Fundamental Planes is due to the presence of young stars in preferentially low-mass early-type galaxies.

• Composites Research
• /
• v.18 no.3
• /
• pp.14-20
• /
• 2005

This paper presents a study on the permittivities of the carbon black/epoxy composite at microwave frequency. The measurements were performed at the frequency band of $1\;GHz\~18\;GHz$. The experimental data show that the complex permittivities of composites depend strongly on the natures and concentrations of the carbon black dispersion. The frequency characteristics of dielectric constants and ac conductivities of composites show the good conformity with descriptions of the percolation theory, satisfying the general scaling relation. The measuring frequency band is over the critical frequency, below that the ac conductivities of composites are constant to the frequency. The values of dielectric constants and ac conductivities have consistent relationships with the carbon black concentration. The A new scheme, that is a branch of Lichtenecker-Rother formula, is proposed to obtain a mixing law to describe the complex permittivities of the composites as function frequency and concentration of carbon black.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.44 no.7 s.361
• /
• pp.1-6
• /
• 2007

In this paper, the spiral zeroth-order resonance (ZOR) antenna using composite right- and left-handed (CRLH) transmission line is proposed. The zeroth-order resonant characteristics of the antenna are described by dispersion relation of a periodic structure. The size of the $2{\times}2$ spiral ZOR antenna is $0.155{\lambda}_{0}{\times}0.155{\lambda}_{0}$. By increasing shunt inductance of CRLH transmission line, the size of this antenna is reduced by 65% compared with that of a mushroom ZOR antenna. The radiation pattern of this antenna have omnidirectional pattern which is similar to that of mushroom ZOR antenna.

• Korean Chemical Engineering Research
• /
• v.46 no.1
• /
• pp.23-36
• /
• 2008

Polymer-clay nanocomposites, a novel organic-inorganic hybrid, attract much attention from both scientific fields and engineering fields due to their balanced improvements in mechanical properties as well as diffusion behaviors, including flame-retarding and barrier properties, with small amounts of clay. Preparation of polymer-clay nanocomposites, summarized as a process for uniform dispersion of hydrophilic layered clays in hydrophobic polymer matrixes, includes several technologies and scientific phenomena, such as surface-modifications of clay layers, physical properties of clays in liquids and dried states, polymer synthesis, polymer rheology, behaviors of polymer solutions/or monomers in the confined geometry, mechanical properties of polymers and clays. To comprehend complicated physical/chemical phenomena involved in the fabrication of nanocomposites, we reviewed physical properties of clays, structures of clays in nanocomposites, characterization of nanocomposites, the relation between morphology and physical property of nanocomposites, surveyed recent research trends, and then suggested a few strategies or methods for fabrication of nanocomposites reflecting future research directions.

• Structural Engineering and Mechanics
• /
• v.57 no.5
• /
• pp.837-859
• /
• 2016

An efficient shear deformation theory is developed for wave propagation analysis of an infinite functionally graded plate in the presence of thermal environments. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations of the present theory is reduced, and hence, makes it simple to use. The thermal effects and temperature-dependent material properties are both taken into account. The temperature field is assumed to be a uniform distribution over the plate surface and varied in the thickness direction only. Material properties are assumed to be temperature-dependent, and graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The governing equations of the wave propagation in the functionally graded plate are derived by employing the Hamilton's principle and the physical neutral surface concept. There is no stretching.bending coupling effect in the neutral surface-based formulation, and consequently, the governing equations and boundary conditions of functionally graded plates based on neutral surface have the simple forms as those of isotropic plates. The analytic dispersion relation of the functionally graded plate is obtained by solving an eigenvalue problem. The effects of the volume fraction distributions and temperature on wave propagation of functionally graded plate are discussed in detail. It can be concluded that the present theory is not only accurate but also simple in predicting the wave propagation characteristics in the functionally graded plate. The results carried out can be used in the ultrasonic inspection techniques and structural health monitoring.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.1
• /
• pp.36.3-36.3
• /
• 2019

Feedback process is one of the most important topics in the study of AGNs since it plays a key role in linking the SMBHs and their host galaxies. In order to further understand the co-evolution of SMBHs and their host galaxies, we probe the feedback process in local type-2 AGNs with a series of integral-field-spectroscopy observations. In the first part of my talk, I will introduce our GMOS observations of luminous type-2 AGNs at z < 0.1, which are selected using the integrated [O III] kinematics. Based on the dedicated emission-line diagnostics and kinematic studies, we identify the signatures of AGN-driven outflows and quantify the outflow size in the targets with extreme [O III] kinematics. For the targets without extreme [O III] kinematics, we find the presence of weak AGN-driven outflows, which are indicated by the significant differences between the kinematics of gas and stars. Then, I will present our recent study of 40 type-2 AGNs based on the SNIFS IFU. By comparing the radial profile of velocity dispersion of gas and stars, we measure the size of AGN-driven outflows in these targets and extend the outflow size-AGN luminosity relation in our previous GMOS studies. We also discuss the feedback effect of AGN-driven outflows by connecting the outflow velocity and host galaxy properties. These results highlight the importance of spatially-resolved observation in investigating gas kinematics and identifying the signatures of AGN-driven outflows.

• Applied Chemistry for Engineering
• /
• v.10 no.7
• /
• pp.1086-1091
• /
• 1999

$K^+-{\beta}/{\beta}"-Al_2O_3$ in the ternary system $K_2O-MgO-Al_2O_3$ was directly synthesized by solid state reaction. The phase formation and phase relation were carefully investigated in relation to starting composition, calcining temperature and time, and dispersion medium. The optimal synthetic condition was also examined for the formation of ${\beta}"-Al_2O_3$ phase with a maximum fraction. As a composition range, the mole ratio of $K_2O$ to $Al_2O_3$ was changed from 1:5 to 1:6.2 and the amount of MgO used as a stabilizer was varied from 4.2 wt % to 6.3 wt %. The calcining temperature was selected between $1000^{\circ}C$ and $1500^{\circ}C$. At $1000^{\circ}C$, the ${\beta}/{\beta}"-Al_2O_3$ phases began to form resulted from the combining of ${\alpha}-Al_2O_3$ and $KAlO_2$ and increased with temperature rising. All of ${\alpha}-Al_2O_3$ phase disappeared to be homogenized to the ${\beta}/{\beta}"-Al_2O_3$ phase at $1200^{\circ}C$. Near the temperature at $1300^{\circ}C$, the fraction of ${\beta}"-Al_2O_3$ phase showed a maximum value with the composition of $K_{1.67}Mg_{0.67}Al_{10.33}O_{17}$. At temperatures above $1300^{\circ}C$, the fraction of ${\beta}"-Al_2O_3$ phase decreased gradually owing to $K_2O$ loss caused by a high potassium vapor pressure, and the appropriate calcining time was about 5 hours. Acetone was more effective than distilled water as a dispersion medium for milling and mixing.