• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.6
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• pp.481-485
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• 1998

We investigated the generation of high pretilt angle for nematic liquid crystal (NLC) in a cell with obilique non-polarized ultraviolet (UV) light irradiation on mixtured polyimide surface. It was found that the monodomain alignment of NLC is obtained with an angle of incidence of 75∼85 degrees on PI surface. We consider that the monodomain alignment of NLC is attributed to anisotropic dispersion force effect to photo-depolymerization of polymer. We successfully observed that the pretilt angle of NLC is generated above 5 degree with an angle of incidence of 75∼85 degrees. It is considered that the pretilt angle generation NLC is attributed to interaction between the LC molecules and the polymer surfaces.

• Electrical & Electronic Materials
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• v.9 no.3
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• pp.259-264
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• 1996

In this study, we performed a modeling for $K^{+}$ ion-exchanged diffused channel waveguide and waveguide-type optical coupler by Wentzel-Kramer-Brillouin(WKB) dispersion equation, normalized field distribution equation for mode and coupled mode theory, and examined the optical-power-dividing of the optical coupler fabricated by using the modeling condition. The optical-power-dividing was observed at the waveguide-type optical coupler with 3[.mu.m] line-width, 6[.mu.m] space between channel waveguides, and 3[mm] interaction length.h.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.194-197
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• 1995

In this study, we performed a modeling for $K^{+}$ ion-exchanged diffused channel waveguide and waveguide-type optical coupler by WKB(Wentzel-Kramer-Brillouim) dispersion equation, field distribution equation of mode and coupled mode theory, and examined the optical-power-dividing of the optical coupler fabricated by using the modeling condition. The optical-power-dividing was observed at the waveguide-type optical coupler with 3[$\mu\textrm{m}$] line-width, 6[$\mu\textrm{m}$] space between channel waveguides, and 3[mm] interaction length.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.316-316
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• 2006

The preparation of an organic/inorganic polymer hybrid from a novolac derivatives is described. The hybrid was prepared by the acid-catalyzed solgel reaction of phenyl-trimethoxysilane (PhTMOS) in the presence of anisole novolac. The resulting film was transparent and showed a high heat stability. The dispersion of two components might be due to the utilization of the p-p interaction between the phenyl ring of the silica matrix and that of novolac. This makes it possible to prepare a hybrid glass having a highly content of novolac derivatives.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3767-3770
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• 2013

Potassium methylselenite ($KSeO_2(OCH_3)$) was reduced to elemental selenium, Se(0), and then doped onto montmorillonite K 10 (MK10) clay to examine the interaction between elemental mercury (Hg(0)) vapor and Se(0) in an effort to understand the possible heterogeneous reaction of Hg(0) vapor and Se(0) solid. The clay was used as a cost-effective support material for uniform dispersion of Se(0). The Se(0)-doped MK10 showed an excellent reaction performance with Hg(0) under an inert nitrogen gas at 70 and $140^{\circ}C$ in our lab-scale fixed-bed system. However, the precursor, $KSeO_2(OCH_3)$-doped MK10 showed a negligible reaction performance with Hg(0), suggesting that the oxidation state of selenium plays a key role in the reaction of Hg(0) vapor and selenium compounds.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.43-46
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• 2004

Multi-walled carbon nanotubes (MWNTs) produced by chemical vapor deposition were treated with acidic solution for purification and oxidization of CNTs. The surface modification of the oxidized CNTs was achieved by amine treatment and oxygen plasma treatment. The functionalized CNTs were embedded in the epoxy resin by sonication method and the resulting composite was investigated by FESEM. Rheological and mechanical properties of nanocomposites were measured by AR2000 and Instron. The rheological properties and dispersion of modified CNTs/epoxy composites were improved as CNTs were modified, because the modification of CNTs led to a improvement interaction between the CNTs and the epoxy resin. In addition to this, mechanical properties are also improved because of the effective stress transfer between the CNTs and the polymer.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.373-379
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• 2009

Presented in this paper is a new experimental technique to measure material properties of lock plate of gas turbine plants by using ultrasonic guided wave. In comparison with the mechanical destructive testings, material characterization of the Inconel x-750 was nondestructively carried out in a more efficient manner to discriminate the change in elastic moduli and the poisson's ratio attributed to the variation of heat treatment condition. The proposed technique shows a satisfactory feasibility via the comparative experiments with the imported lock plate specimens. It is also expected that the guided wave technique can cover a longer and wider range as a new cost-&-time-saving inspection tool due to the interaction with a greater part of specimen, compared to a conventional local point-by-point scheme.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.755-760
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• 2012

In this study, three dimensional cutting force components and surface roughness appeared in high speed cutting by using tungsten carbide endmill tools implanted ion or not found mutual relations through several analysis of statistical dispersion. It is showed that cutting force(Fx) is affect with spindle speed and feed rate, cutting force(Fy) is affect with spindle speed and ion implantation time and cutting force(Fz) is affect with feed rate in interaction through the statistical method of ANOVA of cutting force and surface roughness, it is analyzed that it is affected of spindle speed and feed rate in surface roughness.

• Structural Engineering and Mechanics
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• v.22 no.6
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• pp.719-739
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• 2006

An analytical method for the free vibration of two circular plates coupled with an inviscid and compressible fluid is developed by the Rayleigh-Ritz method. The fluid is bounded by a rigid cylindrical vessel and two circular plates with an unequal thickness and diameter. It was found that the theoretical results could predict well the fluid-coupled natural frequencies with an excellent accuracy when compared with the finite element analysis results. As the fluid thickness increases or the plate thickness difference increases, an abrupt curve veering in the natural frequency loci of the neighboring modes and drastic changes in the corresponding mode shapes are observed. The mode localization frequently appears in the higher modes and in the wide gap between the plates because of a decrease in the fluid coupling owing to the fluid dispersion effect.

• Journal of the Korean Chemical Society
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• v.16 no.3
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• pp.135-141
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• 1972

In the past years, a number of theories have been published to elucidate the structure of liquid water. common to most of these theories is that water mainly consist of several different kinds of clusters and also hydrogen bonds in water may be bent to some degree. Recentrly, in a series of paper, Jhon and Eyring successfully explained thermodynamic, dielectric, surface and transport properites of water, assuming that it contains small domains of about 46 molecules. According to the theory, the cluster size does not change with temperature, but the cluster concentration changes. In this paper, the potential function for the hydrogen bond, the dispersion energy and dipole-dipole interaction terms. The calculated results show that the domain of nearly 46 molecules is energetically most probable, and its size is independent of temperature. And also, we evaluated the effect of angel variation of the bent hydrogen bond. In addition, the relaxation energy different for ice and water is also explained by this method.