• Macromolecular Research
• /
• v.13 no.2
• /
• pp.156-161
• /
• 2005

The thermal transitions of a nylon 6/layered silicate nanocomposite were studied by differential scanning calorimetry and in-situ synchrotron X-ray diffraction. The drawn film of the nylon 6/layered silicate nanocomposite typically showed three endotherms in the DSC thermogram; a very broad endotherm at $\sim120^{\circ}C(T_{1})$, a double-melting endotherm at $\sim215^{\circ}C(T_{2})$, and a high temperature endotherm at $\sim240^{\circ}C(T_{3})$. The drawn film of the nylon 6/ layered silicate nanocomposite was comprised of a mixture of the $\alpha and \gamma$ forms, with $the \alpha form$ being generated by drawing the pressed film having $the \gamma form$. The melting and crystallization of the crystals were observed at the above thermal transitions during the heating experiment performed at the Pohang X-ray synchrotron radiation source (4C2). The newly generated form was meta-stable and melted $at {\sim}T_{1}$. The double-melting $at {\sim}T_{2}$ was due to the exothermic crystallization of $the \alpha form$ during the main endothermic melting of $the \gamma form$. $The \alpha form$ crystallized $at {\sim}T_{2}$ and melted $at {\sim}T_{3}$.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.2
• /
• pp.43-51
• /
• 2014

Multi-view video including depth image is necessary to develop a new compression encoding technique for storage and transmission, because of a huge amount of data. Layered depth image is an efficient representation method of multi-view video data. This method makes a data structure that is synthesis of multi-view color and depth image. This efficient method to compress new contents is suggested to use layered depth image representation and to apply for video compression encoding by using 3D warping. This paper proposed enhanced compression method using layered depth image representation and H.264/AVC video coding technology. In experimental results, we confirmed high compression performance and good quality of reconstructed image.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.2
• /
• pp.122-127
• /
• 2013

Layered-type dielectric waveguide filters were designed. As the order of layers increased the fabrication process for dielectric waveguide filters which the resonator parts were connected by the lateral direction has many difficulties. The proposed structure in this report was designed based on the layered-type for the some parts of resonators. The size of layered-type dielectric waveguide filters installed on the PCB surface were reduced at 25% as compared with the usual waveguide filters by using a relative dielectric constant 22.

• Biomaterials and Biomechanics in Bioengineering
• /
• v.2 no.2
• /
• pp.85-96
• /
• 2015

This study developed biodegradable bi-layered drug-eluting beads and investigated the in-vitro release of fluorouracil and cisplatin from the beads. To manufacture the drug-eluting beads, poly[(d,l)-lactide-co-glycolide] (PLGA) with lactide:glycolide ratios of 50:50 and 75:25 were mixed with fluorouracil or cisplatin. The mixture was compressed and sintered at $55^{\circ}C$ to form bi-layered beads. An elution method was employed to characterize the release characteristic of the pharmaceuticals over a 30-day period at $37^{\circ}C$. The influence of polymer type (i.e., 50:50 or 75:25 PLGA) and layer layout on the release characteristics was investigated. The experiment suggested that biodegradable beads released high concentrations of fluorouracil and cisplatin for more than 30 days. The 75:25 PLGA released the pharmaceuticals at a slower rate than the 50:50 PLGA. In addition, the bi-layered structure reduced the release rate of drugs from the core layer of the beads. By adopting the compression sintering technique, we will be able to manufacture biodegradable beads for long-term drug delivery of various anti-cancer pharmaceuticals.

• BioChip Journal
• /
• v.12 no.4
• /
• pp.280-286
• /
• 2018

Hydrogel scaffolds composed of multiple components are promising platform in tissue engineering as a transplantation materials or artificial organs. Here, we present a new fabrication method for implementing multi-layered macroscopic hydrogel scaffold composed of multiple components by controlling height of hydrogel layer through precise control of ultraviolet (UV) energy density. Through the repetition of the photolithography process with energy control, we can form several layers of hydrogel with different height. We characterized UV energy-dependent profiles with single-layered PEGDA posts photocrosslinked by the modular methodology and examined the optical effect on the fabrication of multi-layered, macroscopic hydrogel structure. Finally, we successfully demonstrated the potential applicability of our approach by fabricating various macroscopic hydrogel constructs composed of multiple hydrogel layers.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1999.10a
• /
• pp.257-266
• /
• 1999

This paper presents a method of seismic analysis for a cylindrical liquid storage structure on/in horizontally layered half.space considering the effects of the interior fluid and exterior soil medium in the frequency domain. To capture the essence of fluid-structure-soil interaction effects effectively, a mixed finite element with two-field (u, p) approximation is employed to model the compressive inviscid fluid, while the structure and soil medium are presented by the 3-D axisymmetric finite elements and dynamic infinite elements. The present FE-based method can be applied to the system with complex geometry of fluid region as well as with inhomogeneous near-field soil medium, since it can directly model both the fluid and the soil. For the purpose of verification, dominant peak frequencies in transfer functions for horizontal motions of cylindrical fluid storage tanks with rigid massless foundation on a homogeneous viscoelastic half.space are compared with those by two different added mass approaches for the fluid motion. The comparison indicates that the Present FE-based methodology gives accurate solution for the fluid-structure-soil interaction problem. Finally, as a demonstration of versatility of the present study, a seismic analysis for a real-scale LNG storage tank embedded in layered half.space is carried out, and its member forces along the height of the structure are compared with those by an added mass approach developed by the present writers.

• Journal of the Korean Ceramic Society
• /
• v.42 no.4
• /
• pp.292-297
• /
• 2005

$LiMO_{2}(M=Co,Ni)$ samples were synthesized with $Li_{2}CO_{3},\;Co_{3}O_{4}$, and NiO by the solid-state reaction method. In the case of $LiCoO_{2}$, at low temperature$(T=400^{\circ}C)$ spinel structure was synthesized and the obtained spinel phase was transformed to layered phase at high temperature$(T\ge600^{\circ}C)$. The phase transition behaviors of $LiCoO_{2}$ were investigated with various heating temperature and time. The rate of transition was directly proportional to the concentrations of reactant, and activation energy of reaction was around 6.76 kcal/mol. When CoO(rock salt structure) was used as a starting material instead of $Co_{3}O_{4}$(spinel structure), layered structure of $LiCoO_{2}$ was obtained at low temperature. In the case of $LiNiO_{2}$ the transition from layered structure to rock salt structure occurred easily by disordering/ordering reaction, but did not occur in $LiCoO_{2}$. The difference in metal ion radii in $LiCoO_{2}$ and $LiNiO_{2}$ results in different behaviors of phase transitions.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1998.08a
• /
• pp.40.3-40
• /
• 1998

• Polymer(Korea)
• /
• v.30 no.1
• /
• pp.56-63
• /
• 2006

We have synthesized two types of diamine monomers containing various chain length to prepare polyimides with layered structure. By using these diamines, homo-polyimides and co-polyimides having hydrophobic and hydrophilic segment of flexible side chain were synthesized. The segregated layered structures were formed by repulsive force with main chain as the side chains reach a critical length because the rigid main chains are packed into layered structure with the flexible side chains occupying the space between layers. As a result, the gallery space of each homo-polyimide was increased at spacing of $32.7\~48{\AA}\;or\;7\~10.5{\AA}$ as the increased hydrophobic or hydrophilic side chain length through X-ray diffraction. The gallery space of co-polyimides was also showed similar phenomenon by repulsive force of side chains with different properties. We have also confirmed that gallery space and molar volume were significantly depended on length of flexible side chain via molecular modeling.

• The Journal of the Petrological Society of Korea
• /
• v.16 no.3
• /
• pp.162-179
• /
• 2007

Macheon Layered Intrusion (MLI) which intruded into Precambrian gneiss complex of the northern Jirisan area, southeastern part of Youngnam (or Sobaeksan) Massif, is a layered mafic-ultramafic complex of Triassic age (ca. 223 Ma). The MLI is divided into Layered Series and Laminated Series. Layered Series is subdivided into Central Zone (Lower Zone) consisting of olivine gabbros and Peripheral Zone (Middle or Upper Zone) consisting of hornblende gabbros based on the type of cumulus texture and the main mafic phase. The Central Zone of Layered Series comprises thinly laminated olivine gabbros and uniform or thickly laminated coarse olivine gabbros which consist of mela-gabbro, troctolite, leuco-troctolite, and anorthositic rocks. Laminated Series is also subdivided into quartz-bearing biotite-pyroxene gabbros and homblende diorite and both have variable amount of interstitial quartz and microcline. Laminated series display moderately to slightly developed igneous lamination which is defined by the planar alignment of lath-shape plagioclases. Chilled margin of quartz-bearing biotite-pyroxene gabbro with surrounding Precambrian gneisses insists shallower intrusion of more felsic cognate magma evolved in the deep a little later. Rocks of Layered Series have orthocumulus to adcumulus olivine, adcumulus to intercumulus plagioclase, and intercumulus to heteradcumulus pyroxene and hornblende. Magmatic modally grading, folding, and cross-lamination are not rarely occurred in thinly layered rocks. These textural characteristics define main mechanisms of the formation of layered and laminated structure in mafic-ultramafic rocks of Macheon Layered Intrusion are gravity settling and in-situ crystallization associated with slumping and density current.