• Korean Journal of Crystallography
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• v.6 no.1
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• pp.1-13
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• 1995

Cr:A12O3 and Ti:A12O3 single crystals were grown by Czochralski method, and the effects of crystal growth parameters such as pulling rate, rotation rate, dopant and growth atmosphere on crystal quality were investigated. And spectroscopic properties including lasing efficiency were also measured. Single crystals, sized of 20mm in diameter and 100-135mm in length, were successfully grown from the seed of <001> direction. With the doping level of 0.5w/o Cr2O3, pulling rate 2.0mm/hr, rotation rate of 30rpm and inert atmosphere by nitrogen gas, high quality crystals of Cr:A12O3 were grown. While in case of Ti:A12O3 crystals, high quality crystals were grown under the conditions of the doping level of 0.25w/o TiO2, pulling rate of 1.5mm/hr, rotation rate of 30rpm and reducing atmosphere by hydrogen - nitrogen mixed gas. It was confirmed that Cr3+ ion which maintains its ionoc valence during growth easily de-bubbled than Ti4+ ion which changes its valence, Fe3+ ion also has do-bubbling effect to Ti:A12O3 crystal and the reducing atmosphere by 90% N2 - 10% H2 mixed gas gave effective result on the changing of Ti4+ to Ti3+ and de-bubbling. As a result of spectroscopic measurements of Cr:A12O3 crystal, 4A2 →4F2 and 4F1 absorption transitions and E →4A2(R1) and 2A →4A2(R2) fluorenscence transitions were confirmed. And it was measured that wavelengths of laser R1 and R2 transitions were 696±5nm and 692±5nm respectively, line width of these transitions were 12A, and life-time of fluorenscence was 152μsec. In case of Ti:A12O3 crystals, it was confirmed that absortion transition of 4T2→4E and fluorescence transition of 4E→4T2 with wide range of 650-1050nm was occured. And 147μsec of life-time of fluorescence, 125.4 of figure of merit and 9% of laser efficience were also measured.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.6
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• pp.41-50
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• 1995

A state-of-the-arts GaAs power metal semiconductor field effect transistor (MESFET) for 3.3V operation digital hand-held phone at 900 MHz has been developed for the first time, The FET was fabricated using a low-high doped structures grown by molecular beam epitaxy (MBE). The fabricated MESFETs with a gate width of 16 mm and a gate length of 0.8 .mu.m shows a saturated drain current (Idss) of 4.2A and a transconductance (Gm) of around 1700mS at a gate bias of -2.1V, corresponding to 10% Idss. The gate-to-drain breakdown voltage is measured to be 28 V. The rf characteristics of the MESFET tested at a drain bias of 3.3 V and a frequencyof 900 MHz are the output power of 32.3 dBm, the power added efficiency of 68%, and the third-ordr intercept point of 49.5 dBm. The power MESFET developed in this work is expected to be useful as a power amplifying device for digital hand-held phone because the high linear gain can deliver a high power added efficiency in the linear operation region of output power and the high third-order intercept point can reduce the third-order inter modulation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.399-404
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• 2001

In CNC machining, a 3D(3-dimension) linear segment and a 2D(2-dimension) circular arc are general forms given by CAD/CAM system. Generally, the 2D circular arc machining is processed using dividing into some linear segments. A 3D circular arc also don't exist in the standard form of NC data. This paper present a algorithm and method for real-time machining of a circular arc(not only the 2D one, but also the 3D one). The 3D circular arc machining is based on the 2D circular arc machining. It only needs making a new coordinate system, converting given 3D points(a start point, a end point, and a center point of a 3D circular arc) into points of the new coordinate system, and processing a inverse transformation about a interpolated point. The proposed algorithm was implemented and simulated on PC system. It was confirmed to give a gcod result.

• Honam Mathematical Journal
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• v.38 no.4
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• pp.753-782
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• 2016

In this paper we deduce the number of representations of a positive integer n by each of the six triangular forms as $${\frac{1}{2}}x_1(x_1+1)+{\frac{3}{2}}x_2(x_2+1)+{\frac{3}{2}}x_3(x_3+1)+{\frac{3}{2}}x_4(x_4+1),\\{\frac{1}{2}}x_1(x_1+1)+{\frac{1}{2}}x_2(x_2+1)+{\frac{3}{2}}x_3(x_3+1)+{\frac{3}{2}}x_4(x_4+1),\\{\frac{1}{2}}x_1(x_1+1)+{\frac{1}{2}}x_2(x_2+1)+{\frac{1}{2}}x_3(x_3+1)+{\frac{3}{2}}x_4(x_4+1),\\x_1(x_1+1)+x_2(x_2+1)+{\frac{3}{2}}x_3(x_3+1)+{\frac{3}{2}}x_4(x_4+1),\\x_1(x_1+1)+{\frac{3}{2}}x_2(x_2+1)+{\frac{3}{2}}x_3(x_3+1)+3x_4(x_4+1),\\{\frac{1}{2}}x_1(x_1+1)+{\frac{1}{2}}x_2(x_2+1)+3x_3(x_3+1)+3x_4(x_4+1).$$

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.656-661
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• 2011

5-(3,4,5-Triethoxyphenyl)-1,3,4-oxadiazole-2-thiol 6 on treatment with substituted 3-(bromomethyl)-2-chloroquinoline or 2-(p-tolyloxy)-3-(bromomethyl)quinoline 4a-j afforded the corresponding 3-((5-(3,4,5-triethoxyphenyl)-1,3,4-oxadiazol-2-ylthio)methyl)-2-chloroquinoline or 3-((5-(3,4,5-triethoxyphenyl)-1,3,4-oxadiazol-2-ylthio)methyl)-2-(p-tolyloxy)quinoline 7a-j, in the presence of $K_2CO_3$ and DMF under stirring at ambient temperature. All the synthesized compounds were further screened for their antibacterial activities. Some of our compounds showed excellent antibacterial activities against test organisms and reference standard.

• Journal of Life Science
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• v.29 no.3
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• pp.369-375
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• 2019

Microtubules form through the polymerization of ${\alpha}-$ and ${\beta}-tubulin$, and tubulin transport plays an important role in defining the rate of microtubule growth inside cellular appendages, such as the cilia and flagella. Heterotrimeric kinesin 2 is a molecular motor member of the kinesin superfamily (KIF) that moves along the microtubules to transport multiple cargoes. It consists of two motor subunits (KIF3A and KIF3B) and a kinesin-associated protein 3 (KAP3), forming a heterotrimeric complex. Heterotrimeric kinesin 2 interacts with many different binding proteins through the cargo-binding domains of the KIF3s, but these binding proteins have not yet been specified. To identify these proteins for KIF3A, we performed yeast two-hybrid (Y2H) screening and found a specific interaction with ${\beta}2-tubulin$ (Tubb2), a microtubule component. Tubb2 was found to bind to the cargo-binding domain of KIF3A but did not interact with KIF3B, KIF5B, or kinesin light chain 1 in the Y2H assay. The carboxyl-terminal region of Tubb2 is essential for interaction with KIF3A. Other Tubb isoforms, including Tubb1, Tubb3, Tubb4, and Tubb5, also interacted with KIF3A in the Y2H screening. However, ${\alpha}1-tubulin$ (Tuba1) did not interact with KIF3A. In addition, an antibody to KIF3A specifically co-immunoprecipitated the KIF3B and KAP3 associated with Tubb2 from mouse brain extracts. In combination, these results suggest that a heterotrimeric kinesin 2 motor protein is capable of binding to tubulin and may transport it in cells.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.2985-2990
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• 2012

New thiazoline derivatives 7a-c, and thiophenes 9a-c linked to indole moiety were easily prepared via the reaction of the acrylamide derivative 3 with phenacyl bromides 4a-c, depending on the reaction conditions. In addition, the reaction of compound 3 with hydrazonoyl chlorides 11a-f afforded a series of 1,3,4-thiadiazole derivatives 13a-f. Moreover, coupling of 3-(3-methyl-1H-indol-2-yl)-3-oxopropanenitrile (2) with the diazonium salts of 3-phenyl-5-aminopyrazole 16 or 3-amino-1,2,4-triazole 17 gave the corresponding hydrazones 18 and 19, respectively. Cyclization of the latter hydrazones yielded the corresponding pyrazolo[5,1-c]-1,2,4-triazine and 1,2,4-triazolo[5,1-c]-1,2,4-triazine derivatives 20 and 21, respectively. The structures of the synthesized compounds were assigned on the basis of elemental analysis, IR, $^1H$ NMR and mass spectral data. All the synthesized compounds were tested for in vitro activities against certain strains of fungi such as Aspergillus niger, Aspergillus nodulans, Alternaria alternate. Compounds showed marked inhibition of fungal growth nearly equal to the standards.

• KSBB Journal
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• v.26 no.5
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• pp.439-442
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• 2011

1,2-propanediol (1,2-PD) is a commodity chemical that is currently produced from petrochemical derivatives. Saccharomyces cerevisiae is well characterized and a successful industrial microorganism to enable the improvement of the 1,2-propanediol production by metabolic engineering. A recombinant S. cerevisiae M3G3 was used to produce 1,2-propanediol. S. cerevisiae M3G3 is the diploid strain that contains 3 copies of mgs (methylglyoxal synthase) and gldA (glycerol dehydrogenase). S. cerevisiae M3G3 was cultivated at various culture conditions by changing culture temperature, glucose concentration, and inducer concentration. Also the effect of induction time was studied to optimize the production of 1,2-propanediol. Batch and fed-batch cultivation of S. cerevisiae M3G3 was performed by using a 5 L jar fermenter. The highest concentration of 1,2-propanediol in batch cultivation was 0.86 g/L and it was further improved to 1.33 g/L in fed-batch cultivation.

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.399-403
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• 2002

The complex of iron(II) tris(3-Br-phen) (3-Br-phen; 3-bromo-1,10-phenanthroline) was prepared as a precursor of electropolymerization and the crystal structure of [Fe(3-Br-phen)3]($PF_6$)2${\cdot}$CH3CN with a distorted octahedral geometry has been investigated. The reductive electropolymerization of $>[Fe(3-Br-phen)3]^{2+}$ complex onto the surface of a glassy carbon electrode and indium tin oxide (ITO) optically transparent electrode were performed in acetonitrile at room temperature. Thin film of poly-$>[Fe(3-Br-phen)3]^{2+}$ formed was adherent, electroactive and stably deposited on a glassy carbon disk electrode. The thin metallopolymeric film formed was also confirmed by absorption spectroscopy.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.2
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• pp.3-14
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• 2013

In this paper, key design issues and considerations for Signal Integrity(SI) and Power Integrity(PI) of a TSV-based 3D IC are introduced. For the signal integrity and power integrity of a TSV-based 3-D IC channel, analytical modeling and analysis results of a TSV-based 3-D channel and power delivery network (PDN) are presented. In addition, various design techniques and solutions which are to improve the electrical performance of a 3-D IC are investigated.