• Kyungpook Mathematical Journal
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• v.59 no.2
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• pp.315-324
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• 2019

In this note we introduce a local-cubically hyponormal weighted shift of order ${\theta}$ with $0{\leq}{\theta}{\leq}{\frac{\pi}{2}}$, which is a new notion between cubic hyponormality and quadratic hyponormality of operators. We discuss the property of flatness for local-cubically hyponormal weighted shifts.

• Journal of the Chungcheong Mathematical Society
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• v.4 no.1
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• pp.103-113
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• 1991

Some properties of a path space and the fundamental group ${\sigma}(X,x_0,G)$ of a topological transformation group (X, G, ${\pi}$) are described. It is shown that ${\sigma}(X,x_0,H)$ is a normal subgroup of ${\sigma}(X,x_0,G)$ if H is a normal subgroup of G ; Let (X, G, ${\pi}$) be a transformation group with the open action property. If every identification map $p:{\Sigma}(X,x,G)\;{\longrightarrow}\;{\sigma}(X,x,G)$ is open for each $x{\in}X$, then ${\lambda}$ induces a homeomorphism between the fundamental groups ${\sigma}(X,x_0,G)$ and ${\sigma}(X,y_0,G)$ where ${\lambda}$ is a path from $x_0$ to $y_0$ in X ; The space ${\sigma}(X,x_0,G)$ is an H-space if the identification map $p:{\Sigma}(X,x_0,G)\;{\longrightarrow}\;{\sigma}(X,x_0,G)$ is open in a topological transformation group (X, G, ${\pi}$).

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.9
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• pp.1446-1451
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• 2013

The quality characteristics of pork patty prepared with chitosan containing preservatives during storage at $4^{\circ}C$ were investigated to improve its functional property and shelf life using food preservatives of natural origin (PI; 0.1% chitosan, 2.5% citric acid, 100 ppm grapefruit seed extract, 0.2% adipic acid, 0.1% Cinnamomum extract, D.W. 97.09% and PII; 0.1% chitosan, 2.5% citric acid, 100 ppm grapefruit seed extract, 0.2% adipic acid, 0.1% Lysimachia christinae Hance extract, D.W. 97.09%). The sensory qualities (taste, appearance, texture and overall acceptability) of patties preserved with PI (1, 3 and 5%) and PII (1, 3 and 5%) were also investigated. The taste and overall acceptability of patties prepared with 1% PI and 1% PII were higher than those of the control. The DPPH radical scavenging activities of the control, 1% PI and 1% PII treated patties were 13.54%, 21.78% and 14.07%, respectively. The total aerobes and coliform count of patties preserved with 1% PI were $10^4$ CFU/g and $10^2$ CFU/g, respectively, after 10 days storage at $4^{\circ}C$. Cooking loss from 1% PI and 1% PII treated patties was lower than that of from the control. Water holding capacity was the highest for 1% PI (65.84%), followed by 1% PII and then the control. The shelf life of patties prepared with 1% PI and 1% PII was extended by about 5 days relative to the control at $4^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1021-1025
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• 2009

A novel supramolecular network containing binuclear copper unit $[Cu(phen)_{2}({\mu}-ID\;A)Cu(phen){\cdot}(NO_{3})](NO_{3}){\cdot}4(H_{2}O)$ (1) was synthesized through the self-assembly of iminodiacetic acid ($H_2IDA$) and 1,10-phenanthroline (phen) in the condition of pH = 6. It has been characterized by the infrared (IR) spectroscopy, elemental analysis, single crystal X-ray diffraction, and thermogravimetric analysis (TGA). 1 shows a 2-D supramolecular structure assembled through strong and unique $\pi-\pi$ packing interactions. Density functional theory (DFT) calculations show that theoretical optimized structures can well reproduce the experimental structure. The TGA and powder X-ray diffraction (PXRD) curves indicate that the complex 1 can maintain the structural integrity even at the loss of free water molecules. The magnetic property is also reported in this paper.

• Journal of the Korean Chemical Society
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• v.45 no.5
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• pp.436-441
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• 2001

The emission and excitation spectra of mer-[Cr(dien)(glygly)]ClO$_4$(glygly=glycylglycinate;dien=N-(2-aminoethyl)-1,2-ethanediamine) taken at 77 K are reported. The infrared and visible spectra at 298 K are also measured. The twelve electronic bands due to spin-allowed and spin-forbidden transitions are assigned. Using the observed transitions, a ligand field analysis has been performed to determine the bonding property of coordinated atoms in the chromium(III) complex. It is confirmed that the amine nitrogen atoms of the dien and glygly have strong $\sigma$-donor characters, but the peptide nitrogen of glygly has weak $\pi$-donor property toward chromium(III) ion.

• Macromolecular Research
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• v.17 no.9
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• pp.672-681
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• 2009

A series of inert and photo-stable Er(III)-encapsulated complexes based on ${\pi}$-extended dendritic anthracene ligands bearing G3-aryl-ether dendron ([G3-AnX]-$CO_2H$), which retain different ${\pi}$-bridging systems, such as single (X= S), double (X= D) and triple (X= T) bonds was designed and synthesized to establish the structure-property relationship. The near infrared emission intensities of Er(III)-encapsulated complexes were enhanced dramatically by increasing the ${\pi}$-conjugated extension of anthracene ligands. The time-resolved luminescence spectra show monoexponential decays with a lifetime of $2.0{\sim}2.4ms$ for $Er^{3+}$ ions in thin films, and calculated intrinsic quantum yields of $Er^{3+}$ ions are in the range of $0.025{\sim}0.03%$. As a result, all Er(III)-encapsulated dendrimer complexes exhibit the near IR emission with the following order: $Er^{3+}-[G3-AnD]_3$(terpy) > $Er^{3+}-[G3-AnS]_3$(terpy) ${\approx}$ $Er^{3+}-[G3-AnT]_3$(terpy), because $Er^{3+}-[G3-AnD]_3$(terpy) has a higher relatively spectral overlap J value and energy transfer efficiency. In addition, the lack of detectable phosphorescence and no significant spectral dependence of the ${\pi}$-extended anthracene moieties on the solvent polarity support energy transfer from their singlet state to the central $Er^{3+}$ ion taking place in $Er^{3+}-[G3-AnX]_3$(terpy).

• Polymer(Korea)
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• v.34 no.5
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• pp.480-484
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• 2010

A series of poly(amic acid)s(PAAs) was prepared by reacting 4,4'-(4,4'-isopropylidenediphenoxy) bis(phthalic anhydride)(BPADA) as the anhydride monomer and 2,2'-bis(trifluoromethyl) benzidine (TFB), bis(3-aminophenyl)sulfone (APS), 4,4'-methylenebis-(2-methylcyclohexylamine) (MMCA), or bis[4-(3-aminophenoxy) phenyl] sulfone (BAPS) as the amine monomer with 5 mol% melamine in N,N-dimethylacetamide (DMAc). Colorless and transparent polyimide (PI) films were obtained by casting the PAAs at various heat treatment temperatures. The thermo-mechanical properties and optical transparency of the PI films were investigated. The thermal properties of the PI films were examined using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and thermomechanical analysis (TMA), and their optical transparency were measured by spectrophotometry. The coefficient of thermal expansion (CTE) and yellow index (YI) values of all samples were in the range of $48.53-64.24ppm/^{\circ}C$ and < 3.0, respectively.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.88-94
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• 1999

Recently, PTFE-polyimide composites are being used self-lubricating parts for industrial field. Thus, this study is mainly concerned with friction and wear properties for the piston ring of non-lubricating air compressor which made of PTFE-polyimide composites. The friction and wear test was carried out for the different composition ratio under the atmosphere room temperature and constant load of 7.69N and their friction and wear properties were compared with each other at various sliding speed. Notable results are summarized as follows. PTFE 100% showed that friction coefficient was almost same values at 0.94 and 1.88m/s but the value was decreased at 2.83m/s because the friction temperature is higher than low speed. PTFE 80%-PI 20% showed the lowest mean friction coefficient at 2.83m/s. PTFE 20%-PI 80% showed the highest friction coefficient at 0.94m/s and the value was decreased at high speed but the value is higher than other materials except PTFE 100 %. PI 100% showed the highest friction coefficient at 0.94 and 1.88m/s because adhesive wear mainly occurred that speed. PTFE 100% showed highest specific wear rate on the whole. Specific wear rate of PTFE 80%-PI 20% was almost the same value with PTFE 20%-PI 80%. PI 100% showed the lowest value at high sliding speed because the friction surface was thicken and carbonated by high friction temperature.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.74-80
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• 2000

In this paper, we proposed the MAC protocol and analyzed the performance for CATV/LAN network which was based upon HFC(hybrid optic coaxial) increased abruptly as alternative method of high speed network. Upstream channel which analyzed very deeply for CATV/LAN network have the preferential access property depending upon that position and unidirectional property. To solve this fairness problem, we propose the CSMA-CD/U/P protocol that transm it as $P_i$ probability although data packets is immediately transmitted when it was occurred. As the analytic result and simulation, we obtained $P_i$ value and its average delay time. Also, we get its variance value and queue length distribution. The mean delay time and queue length increase as the load and number of stations increase in the CATV/LAN network.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.2
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• pp.169-172
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• 2002

The voltage holding ratio(VHR) and the residual DC property in the in-plane switching (IPS) cells on a polyimide surface was studied. Several IPS cells which have different concentrations of cyano liquid crystals (LCs) were fabricated. We found that the VHR of the IPS cell was decreased with increasing concentration of cyano LCs. Also, the VHR of the IPS cell was increased with increasing specific resistivity of fluorine LCs. The residual DC voltage of the IPS cell by capacitance-voltage (C-V) hysteresis method was decreased with increasing concentration of cyano LCs. The residual DC property of the IPS cell on the rubbed PI surface can be improved by high polarity of cyano LC.