• Transactions on Electrical and Electronic Materials
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• v.15 no.6
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• pp.305-308
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• 2014

Organosilyl-modified and star-shaped poly (${\varepsilon}$-caprolactone) (m-PCL) was prepared, and added to polymethylsilsesquioxane (PMSSQ), to make composites. The end groups of m-PCL are chemically similar to PMSSQ, and m-PCL mixed well with PMSSQ in the composite. Porous PMSSQ film was made by further calcination of the composite film at elevated temperature. m-PCL-templated PMSSQ and the as-prepared porous PMSSQ were structurally, optically, and thermally characterized in thin films. The chemical binding of m-PCL and PMSSQ effectively suppressed the phase separation of PMSSQ and m-PCL during the curing process. After calcination at elevated temperature, there remained many pores in the PMSSQ matrix. The refractive indices of the resulting porous PMSSQ thin films decreased with increase of the film porosities, depending on the initial m-PCL loadings.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3345-3356
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• 1994

A general purpose program, TURBO-3D, for the analysis of 3-D fluid flow in complex geometry has been developed, which employs a standard $k-\varepsilon$ turbulence model and a general nonorthogonal grid system. For the purpose of verification of the program and testing the applicability, turbulent flows in an S-shaped diffuser and turbulent flows over an backward facing step are solved and compared with the earlier results. Comparison with the results by the STAR-CD program has been also made for the same flow configuration and grid structure. The agreements are excellent and hence the program has been verified. Since the present program is applicable only on limited flow phenomena and lacks the pre-and post processor, further improvements toward these directions are being made.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.48-49
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• 2006

The incorporation of heparin to biomaterials has been widely studied to improve the biocompatibility (blood and cell) of biomaterials surfaces. In our laboratory, various kinds of heparinized polymers including heparinized thermosensitive polymers ($Tetronic^{(R)}$-PLA(PCL)-heparin copolymers) and star-shaped PLA-heparin copolymers have been developed as a novel blood/cell compatible material. These heparinized polymers have demonstrated their unique properties due to bound heparin, resulting in improved biocompatibility. These heparinized bioactive polymers can be applied as blood and tissue compatible biodegradable materials in variable medical application such as tissue engineering and drug delivery system.

• Elastomers and Composites
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• v.45 no.2
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• pp.74-79
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• 2010

In this review, the properties of buckminsterfullerene and its organic and polymeric reactions were focused. In addition, polymer blending with $C_{60}$ will be briefly introduced. As soon as $C_{60}$ was discovered, chemists put their efforts to explore its reactivity with other compounds. The knowledge of the organic reactions with $C_{60}$ was extended to construct different types of fullerene polymers such as side chain fullerene polymers, main chain fullerene polymers, star shaped fullerene polymers, and dendritic fullerene polymers.

• Animal Systematics, Evolution and Diversity
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• v.34 no.2
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• pp.110-113
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• 2018

Aphelenchoides nonveilleri $Andr{\acute{a}}ssy$, 1959, belonging to the family Aphelenchoididae Skarbilovich, 1947, is first reported from South Korea. The genus Aphelenchoides Fischer, 1894 includes about 200 species worldwide, but to date only nine Aphelnechoides species have been reported from South Korea. Specimens of A. nonveilleri were collected from the roots and shoot tips of chrysanthemum (Chrysanthemum morifolium Ramat, 1792) from a greenhouse. This species is distinguished from other Aphelenchoides species by its star-shaped mucro on the female tail tip, three lateral incisures, and the length of the post-vulvar uterine sac. Here we provide details of the morphological characters and morpometrics of A. nonveilleri based on optical microscopy.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.25 no.3
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• pp.66-81
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• 2021

In this paper, we review the lowest order staggered discontinuous Galerkin methods on polygonal meshes in 2D. The proposed method offers many desirable features including easy implementation, geometrical flexibility, robustness with respect to mesh distortion and low degrees of freedom. Discrete function spaces for locally H¹ and H(div) spaces are considered. We introduce special properties of a sub-mesh from a given star-shaped polygonal mesh which can be utilized in the construction of discrete spaces and implementation of the staggered discontinuous Galerkin method. For demonstration purposes, we consider the lowest case for the Poisson equation. We emphasize its efficient computational implementation using only geometrical properties of the underlying mesh.

• Bulletin of the Korean Chemical Society
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• v.12 no.2
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• pp.189-193
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• 1991

A series of compounds that contain varying numbers of the same mesogenic structure, biphenyl p-oxybenzoate unit, attached through a pentamethylene spacer to the central benzene ring were prepared and their liquid crystallinity was studied. The mesophase-forming ability of a dimesogenic compound was found to be greatly dependent on whether or not its geometric shape is linear and also on the existence of the pentamethylene spacer between the mesogen and the central core. The presence of the spacer enhanced the capacity of a compound to form a mesophase. In the trimesogenic compound the mesogens were linked to the 1,3,5-positions of the core benzene ring through the spacer. The compound was found to be enantiotropically nematic.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.61.1-61.1
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• 2019

We report about the constellations discovered in Ara-Gaya Malisan tomb 13 of late 5th century. In December 2018, constellation-shaped grooves were newly found on the ceiling of the tomb 13 of the Ara-Gaya (42-532 CE.) polity in Haman(咸安). The tomb 13 is located at the top/center of the Malisan and is one of the largest burial mounds. Grooves were found in one of the slabs of the grave cover-stone (160 ∗ 80~60cm). The total number of grooves are 134 and each groove has a diameter of 1.5~4.0 cm. The grooves were made by pecking or grinding. From the preliminary study, we identified these grooves with traditional constellations such as 房, 心, 尾, 箕, 斗, which correspond to Scorpius and Sagittarius of modern constellations near the Milky Way. It shows that advanced astronomy also existed in Ara-Gaya tomb while star charts were painted in Goguryeo tombs. This carries great importance in studying the development and exchange of astronomy in the Korean Peninsula.

• Polymer(Korea)
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• v.30 no.2
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• pp.146-151
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• 2006

Linear and branched copolymers consisting of poly(ethylene glycol) (PEG) and $Poly({\varepsilon}-caprolactone)$ (PCL) were prepared to compare the characterization of star-shaped copolymers with various molecular architecture. Linear and branched PEG-PCL (1-arm, 2-arm, 4-arm, and 8-arm) copolymers were synthesized by the ring-opening polymerization of ${\varepsilon}-caprolactone$ in the presence of HCl $Et_2O$ as a monomer activator at room temperature. The synthesized copolymers were characterized with $^1H-NMR$, GPC, DSC, and XRD. As a result of the DSC and XRD, each copolymers showed different thermal properties and crystallinity according to the number of ms. The micellar characterization of linear and branched copolymers in an aqueous phase was carried out by using NMR, dynamic light scattering, AM, and fluorescence techniques. The critical micelle concentration (CMC) and diameters of micelles depended on the number of arms. Most micelles exhibited a spherical shape in AFM. In this study, we characterized star-shaped PEG-PCL copolymers and investigated their molecular architecture effect on the various properties. Furthermore, we confirmed that the micelles termed with linear and branched PEG-PCL copolymers have possibility as a potential hydrophobic drug delivery vehicle.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.311-316
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• 2012

Lyman break Galaxies are galaxies selected in the rest-frame ultraviolet. But, one important and missing information for these Lyman break galaxies is the amount of dust attenuation. This is crucial to estimate the total star formation rate of this class of objects and, ultimately, the cosmic star formation density. AKARI, Spitzer and Herschel are therefore the major facilities that could provide us with this information. As part of the Herschel Multi-tiered Extragalactic Survey, we have began investigating the rest-frame far-infrared properties of a sample of more than 4,800 Lyman Break Galaxies in the GOODS-North fiels. Most LBGs are not detected individually, but we do detect a sub-sample of 12 objects at 0.7 < z <1.6 and one object at z = 2.0. The ones detected by Herschel SPIRE have redder observed NUV-U and U-R colors than the others, while the undetected ones have colors consistent with average LBGs at z > 2.5. We have analysed their UV-to-FIR spectral energy distributions using the code cigale to estimate their physical parameters. We find that LBGs detected by SPIRE are high mass, luminous infrared galaxies. They also appear to be located in a triangle-shaped region in the $A_{FUV}$ vs. $logL_{FUV}$ diagram limited by $A_{FUV}$ = 0 at the bottom and by a diagonal following the temporal evolution of the most massive galaxies from the bottom-right to the top-left of the diagram. In a second step, we move to the larger COSMOS field where we have been able to detect 80 Lyman break galaxies (out of ~ 15,600) in the far infrared. They form the largest sample of Lyman break galaxies at z > 2.5 detected in the far-infrared. We tentatively name them Submillimeter Lyman break galaxies (S-LBGs).