• Electrical & Electronic Materials
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• v.8 no.3
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• pp.272-277
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• 1995

We report the properties of optically pumped stimulated emission at room temperature (RT) from column-III nitride semiconductors of GaN, AlGaN/GaN double heterostructure (DH) and AlGaN/GaInN DH which prepared on a sapphire substrate using an AIN buffer-layer by the nietalorganic vapor phase epitaxy (MOVPE) method. The peak wavelength of the stimulated emission at RT from AIGaN/GaN DH is 369nm and the threshold of excitation pumping power density (P$\_$th/) is about 84kW/cm$\^$2/, and they from AlGaN/GaInN DH are 402nm and 130kW/cm$\^$2/ at the pumping power density of 200kW/cm$\^$2/, respectively. The P$\_$th/ of AIGaN/GaN and AlGaN/GaInN DHs are lower than the single layers of GaN and GaInN due to optical confinement within the active layers of GaN and GaInN, respectively.

• Communications of the Korean Mathematical Society
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• v.19 no.2
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• pp.321-328
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• 2004

In this paper, we will prove the following: Let D be a nonempty of a normed linear space X and T : D -> X be a nonexpansive mapping. Let ${x_n}$ be a sequence in D and ${t_n}$, ${s_n}$ be real sequences such that (i) $0\;{\leq}\;t_n\;{\leq}\;t\;<\;1\;and\;{\sum_{n=1}}^{\infty}\;t_n\;=\;{\infty},\;(ii)\;(a)\;0\;{\leq}\;s_n\;{\leq}\;1,\;s_n\;->\;0\;as\;n\;->\;{\infty}\;and\;{\sum_{n=1}}^{\infty}\;t_ns_n\;<\;{\infty}\;or\;(b)\;s_n\;=\;s\;for\;all\;n\;{\geq}\;1\;and\;s\;{\in}\;[0,1),\;(iii)\;x_{n+1}\;=\;(1-t_n)x_n+t_nT(s_nTx_n+(1-s_n)x_n)\;for\;all\;n\;{\geq}\;1.$ Then, if the sequence {x_n} is bounded, then $lim_{n->\infty}\;$\mid$$\mid$x_n-Tx_n$\mid$$\mid$\;=\;0$. This result improves and complements a result of Deng [2]. Furthermore, we will show that certain conditions on D, X and T guarantee the weak and strong convergence of the Ishikawa iterative sequence to a fixed point of T.

• The KIPS Transactions:PartA
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• v.17A no.1
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• pp.1-8
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• 2010

The fault diameter is one of the important measures for transmission rate and reliability of interconnection network. H.-O. Lee et al.[Parallel paths in folded hyper-star graph, Journal of KIPS, Vol.6, No.7, pp.1756-1769, 1999] suggested the node-disjoint paths of FHS (2n,n), and proved that the fault diameter of FHS(2n,n) is less than 2n-1. In this paper, we suggest an advanced node-disjoint paths of FHS(2n,n). We also prove that the wide diameter of FHS(2n,n) is dist(U,V)+4, and the fault diameter of FHS(2n,n) is less than n+2.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.1054-1057
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• 1997

Four kinds of N,N'-bisacrylamide derivatives were synthesized by Scotten-Baumann reaction from acryloyl chloride and several diamines in the presence of triethylamine, and their chemical structures were identified by IR, $^1H-NMR$, and elemental analysis. The yields of the synthesized N,N'- hexamethylenebisacrylamide and N,N'-dodecamethylenebisacrylamide were 56.0% and 70.4%, respectively, and were increased with the increased number of methylene group in the dimines. The yields of the synthesized N,N'-1,4-phenylenebisacrylamide and N,N'-2,6-pyridinebisacrylamide were 80.3% and 83.1%, respectively, which were higher than those of the alkylenebisacrylamide derivatives. The synthesized N,N'-bisacrylamide derivatives can be used to prepare various crosslinked polymers.

• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.163-170
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• 1988

The MNDO calculations were performed on the various rotamers of N-methyl formamide, N,N-dimethyl formamide, N-methyl acetamide, and N,N-dimethylacetamide in order to investigate the contribution of the one-electron and the steric effect on their rotational barriers about the C-N bond. Results show that while the conformational stabilities of formamides depend mainly on the one-electron factor, those of acetamides depend mainly on the steric factor. According to results obtained by calculations on the rotational barriers about C-N bond, for N-monosubstituted amides the steric effect is larger in the rotational ground state than in the transition state and for N,N-disubstituted amides the steric effect is larger in the rotational transition state.

• Kyungpook Mathematical Journal
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• v.49 no.2
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• pp.283-288
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• 2009

Let N be a zero-symmetric near-ring with identity and let ${\Gamma}(N)$ be a graph with vertices as elements of N, where two different vertices a and b are adjacent if and only if + = N, where is the ideal of N generated by x. Let ${\Gamma}_1(N)$ be the subgraph of ${\Gamma}(N)$ generated by the set {n ${\in}$ N : = N} and ${\Gamma}_2(N)$ be the subgraph of ${\Gamma}(N)$ generated by the set $N{\backslash}{\upsilon}({\Gamma}_1(N))$, where ${\upsilon}(G)$ is the set of all vertices of a graph G. In this paper, we completely characterize the diameter of the subgraph ${\Gamma}_2(N)$ of ${\Gamma}(N)$. In addition, it is shown that for any near-ring, ${\Gamma}_2(N){\backslash}M(N)$ is a complete bipartite graph if and only if the number of maximal ideals of N is 2, where M(N) is the intersection of all maximal ideals of N and ${\Gamma}_2(N){\backslash}M(N)$ is the graph obtained by removing the elements of the set M(N) from the vertices set of the graph ${\Gamma}_2(N)$.