• Advances in materials Research
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• v.4 no.4
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• pp.207-214
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• 2015

It has been reported in the technical literature that orotic acid can be used in order to induce improved crystallization of biodegradable and biocompatible polymers like poly(L-lactic acid), polyhydroxybutyrate and poly(hydroxybutyrate-co-hydroxyhexaonat). The expected advantage of the changed crystalline structure is a reinforcing effect of the polymers. A lot of papers reported about the application of inorganic and organic agents for acceleration of heterogeneous nucleation. This study reports on an attempt to use orotic acid as appropriate non-toxic nucleating agent for improving mechanical properties of isotactic polypropylene. Special attention is given to demonstrate the effect of nucleation in a typical melt spinning process in order to improve the mechanical properties. The effects were demonstrated using rheology, thermal analysis and tensile testing.

• Korean Journal of Mathematics
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• v.27 no.3
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• pp.613-627
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• 2019

Consider a connected molecular graph G = (V, E) where V is the set of vertices and E is the set of edges. In G, vertices represent the atoms and edges represent the covalent bonds between atoms. In graph G, every edge (say) e = uv will be connected by two atoms u and v. The edge Szeged index is a topological index which has been introduced by Ivan Gutman. In this paper, we have computed edge Szeged indices of a hydrocarbon family called Benzene ring and is denoted by $(BR)_{n{\times}n}$.

• Korean Journal of Materials Research
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• v.13 no.3
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• pp.195-199
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• 2003

The $p-CdIn_2$$Te_4$single crystal was grown in the three-stage vertical electric furnace by using Bridgman method. The quality of the grown crystal has been investigated by the x-ray diffraction and the photoluminescence measurements. From the photoluminescence spectra of the as-grown $CdIn_2$$Te_4$crystal and the various heat-treated crystals, the ($D^{\circ}$, X) emission was found to be the dominant intensity in the photoluminescence spectrum of the $CdIn_2$T $e_4$:Cd, while the ($A^{\circ}$, X) emission completely disappeared in the $CdIn_2$T $e_4$:Cd. However, the ($A^{\circ}$, X) emission in the photoluminescence spectrum of the $CdIn_2$T $e_4$:Te was the dominant intensity like an as-grown $CdIn_2$T $e_4$crystal. These results indicated that the ($D^{\circ}$, X) is associated with $V_{Te}$ acted as donor and that the ($A^{\circ}$, X) emission is related to $V_{cd}$ acted as acceptor, respectively. The $p-CdIn_2$T $e_4$crystal was found to be obviously converted into the n-type after annealing in the Cd atmosphere. The origin of ( $D^{\circ}$, $A^{\circ}$) emission and its TO phonon replicas is related to the interaction between donors such as $V_{Te}$ or $Cd_{int}$, and accepters such as $V_{cd}$ or T $e_{int}$. Also, the In in the $CdIn_2$X$CdIn_4$was confirmed not to form the native defects because it existed in the stable form of bonds.

• Restorative Dentistry and Endodontics
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• v.25 no.1
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• pp.56-62
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• 2000

The purpose of this study was to assess the effects of restorative materials on the marginal leakage of wedge-shaped class V cavity. The study was performed in vitro in 25 defect-free permanent, extracted teeth. Wedge-shaped class V cavities were prepared and then the teeth were randomly selected and restored according to the following. Group A : restoration with Tetric Ceram(composite resin) Group B : restoration with Tetric flow(flowable resin) Group C : restoration with Compoglass after acid etching(compomer) Group D : restoration with Compoglass(compomer) Group E : restoration with Fuji II LC improved(resin-modified GIC) After thermocycling, the specimens were immersed in 5% basic fuchsin solution for 6 hours and sectioned longitudinally through the center of the restoration. The degree of marginal leakage was measured as the extent of dye penetration under the stereomicroscope. The data were analysed using one-way ANOVA. When significant differences found, multiple comparisons were made using Duncan's Multiple Range Test. The results were as follows: 1. The occlusal margins of all groups except for Fuji II LC improved showed lesser leakage than gingival margins and there was statistically significant difference(p<0.05). 2. At the occlusal margins, group A, B showed same marginal leakage scores, and others were decreased as group C, D, E in that order. There were statistically significant difference between group A, Band group D, E, group C and group E(p<0.05). 3. At the gingival margins, group B, C showed same marginal leakage scores, and others were decreased as group A, D, E in that order. But there was statistically significant difference between group B, C and group E(p<0.05). 4. In the Compoglass restoration, acid-etching technique was beneficial for marginal sealing ability at all of margins. But there was no statistically significant difference (p>0.05). In the restorations for wedge-shaped class V cavities, resin restoration with acid etching technique is recommended.

• The KIPS Transactions:PartA
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• v.18A no.6
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• pp.225-232
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• 2011

Restricted Hypercube-Like (RHL) graphs are a graph class that widely includes useful interconnection networks such as crossed cube, Mobius cube, Mcube, twisted cube, locally twisted cube, multiply twisted cube, and generalized twisted cube. In this paper, we show that for an m-dimensional RHL graph G, $m{\geq}4$, with an arbitrary faulty edge set $F{\subset}E(G)$, ${\mid}F{\mid}{\leq}m-2$, graph $G{\setminus}F$ has a hamiltonian path between any distinct two nodes s and t if dist(s, V(F))${\neq}1$ or dist(t, V(F))${\neq}1$. Graph $G{\setminus}F$ is the graph G whose faulty edges are removed. Set V(F) is the end vertex set of the edges in F and dist(v, V(F)) is the minimum distance between vertex v and the vertices in V(F).

• Proceedings of the KIEE Conference
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• 1985.07a
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• pp.215-218
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• 1985

In this paper, The electron drift velocity was measured from an experimental study of the open end heat pipe system by induced current method as alkali metal vapour was generated in ordinary region of a drift tube. The test condition was alkali metal vapour range from 3.6 to 20.1(Torr), temperature of 667 to 755(K), and E/N of $1{\times}10^{-16}$ to $1{\times}10^{-15}(v.cm^2)$. The results of this study were obtained essentially the same as the extrapolated prediction curve for electron drift velocity in the alkali metal Vapour of J. Lucas et 31 with range of E/N: $1{\times}10^{-17}$ to $1{\times}10^{-16}(v.cm^2)$, and the electron drift velocity was obtained the result an increase in alkali to E/N range from E/N $2.8{\times}10^{-17}$ to $5.6{\times}10^{-16}(v.cm^2)$ (E/N From 2.8 to 50 Td).

• Bulletin of the Korean Mathematical Society
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• v.59 no.1
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• pp.167-177
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• 2022

A vertex v of a graph G = (V, E) is said to ve-dominate every edge incident to v, as well as every edge adjacent to these incident edges. A set S ⊆ V is called a double vertex-edge dominating set if every edge of E is ve-dominated by at least two vertices of S. The minimum cardinality of a double vertex-edge dominating set of G is the double vertex-edge domination number γ_dve(G). In this paper, we provide an upper bound on the double vertex-edge domination number of trees in terms of the order n, the number of leaves and support vertices, and we characterize the trees attaining the upper bound. Finally, we design a polynomial time algorithm for computing the value of γ_dve(T) for any trees. This gives an answer of an open problem posed in [4].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.282-285
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• 2003

Single crystal $CuAlSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $410\;^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$ source at $680\;^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $CuAlSe_2$ thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}\;and\;295\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;2.8382\;eV\;-\;(8.68\;{\times}\;10^{-4}eV/K)T^2/(T\;+\;155\;K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $CuAlSe_2$ have been estimated to be 0.2026 eV and 0.2165 eV at 10 K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the $\Delta$so definitely exists in the ${\Gamma}_5$ states of the valence band of the $CuAlSe_2$. The three photocurrent peaks observed at 10 K are ascribed to the $A_1-$, $B_1-$, and $C_1$-exciton peaks for n = 1.

• Journal of the Korea Society of Computer and Information
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• v.20 no.1
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• pp.227-235
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• 2015

In this paper, I propose a linear time algorithm devised to produce exact solution to NP-complete maximum clique problem. The proposed algorithm firstly, from a given graph G=(V,E), sets vertex $v_i$ of the maximum degree ${\Delta}(G)$ as clique's major vertex. It then selects vertex $v_j$ of ${\Delta}(G)$ among vertices $N_G(v_i)$ that are adjacent to $v_i$, only to determine $N_G(v_i){\cap}N_G(v_j)$ as candidate cliques w and $v_k$. Next it obtains $w=w{\cap}N_G(v_k)$ by sorting $d_G(v_k)$ in the descending order. Lastly, the algorithm executes the same procedure on $G{\backslash}w$ graph to compare newly attained cliques to previously attained cliques so as to choose the lower. With this simple method, multiple independent cliques would also be attainable. When applied to various regular and irregular graphs, the algorithm proposed in this paper has obtained exact solutions to all the given graphs linear time O(n).

• Journal of the Korean Vacuum Society
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• v.15 no.5
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• pp.527-533
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• 2006

Spinel $LiNi_xMn_{2-x}O_4$ thin films were synthesized up to x = 0.9 by a sol-gel method employing spin-coating. The Ni-substituted films were found to maintain cubic structure at low x but to exhibit tetragonal structure for $x{\geq}0.6$. Such cubic-tetragonal phase transition indicates that $Ni^{3+}(d7)$ ions with low-spin $(t_{2g}^6,e_g^1)$ state occupy the octahedral sites of the compound, thus being subject to the Jahn-Teller distortion. By x-ray photoelectron spectroscopy both $Ni^{2+}$ and $Ni^{3+}$ ions were detected. Optical properties of the $LiNi_xMn_{2-x}O_4$ films were investigated by spectroscopic ellipsometry (SE) in the visible?ultraviolet range. The measured dielectric function spectra by SE mainly consist of broad absorption structures attributed to charge-transfer (CT) transitions, $O^{2-}(2p){\rightarrow}Mn^{4+}(3d)$ for 1.9 $(t_{2g})$ and $2.8{\sim}3.0$ eV $(e_g)$ structures and $O^{2-}(2p){\rightarrow}Mn^{3+}(3d)$ for 2.3 $(t_{2g})$ and $3.4{\sim}3.6$ eV $(e_g)$ structures. Also, sharp absorption structures were observed at about 1.6, 1.7, and 1.9 eV, interpreted as due to d-d crystal-field transitions within the octahedral $Mn^{3+}$ ion. The strengths of these absorption structures are reduced by the Ni substitution. Rapid reduction of the CT transition strength involving the eg states for x = 0.6 is attributed to the reduced wavefunction overlap between the $e_g$ and the $O^{2-}(2p)$ states due to the tetragonal extension of the lattice constant by the Jahn-Teller effect.