• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.3
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• pp.270-277
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• 2012

This paper presents a new DAC design strategy to achieve a wideband dynamic linearity by increasing the bandwidth of the output impedance. In order to reduce the dominant parasitic capacitance of the conventional matrix structure, all the cells associated with a unit current source and its control are stacked in a single column very closely (stacked unit cell structure). To further reduce the parasitic capacitance, the size of the unit current source is considerably reduced at the sacrifice of matching yield. The degraded matching of the current sources is compensated for by a self-calibration. A prototype 6-bit 3.3-GS/s current-steering full binary DAC was fabricated in a 1P9M 90 nm CMOS process. The DAC shows an SFDR of 36.4 dB at 3.3 GS/s Nyquist input signal. The active area of the DAC occupies only $0.0546mm^2$ (0.21 mm ${\times}$ 0.26 mm).

• Archives of Pharmacal Research
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• v.20 no.4
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• pp.330-337
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• 1997

Thiocarboxamidocinnamonitrile derivatives 2 under bar a-f reacted with 3-aminopyrazole derivative 3 under bar a-c to give the pyrazole[3, 2-b]pyrimidine derivatives 6 under bar a-p. Compounds 6 under bar a-p were used as starting material for syntheses of several heterocylic coompounds. Dehydrogenation of 6 under bar gave pyrazole[3, 2-b]pyrimidines 10 under bar a-d while its reaction with diethyl oxalate gave 11 under bar. Reactions of 6 under bar with formic acid gave pyrazolopyrimidines 17 under bar a-j, and pyrazolopyrimidopyrimidines 18 under bar a-j.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.238-239
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• 2012

ZnO disk는 Ar 가스의 ON/OFF 사이클을 사용한 기상 이동법으로 성장하였다. 온도 의존성 photoluminescence (PL)은 PL 스펙트럼의 quenching 동작을 관장하는 메커니즘을 연구하기 위해 조사하였다. ZnO disk의 12 K PL 스펙트럼에서 3.364, 3.315, 3.244, 3.212, 3.170, 3.139, 3.100 eV의 피크를 관측되었고, 그것은 각각 excitons bound to neutral donors ($D^{\circ}X$), A-line, first-order longitudinal optical (1LO) phonon replica of A-line (A-1LO), donor-to acceptor pair (DAP), A-2LO, DAP-1LO, A-3LO 이다. $D^{\circ}X$와 A-line 피크는 Varshni 공식에 의해서 피팅을 하였고, 도너 이온화 에너지는 40 meV 이었다. Free excitons, $D^{\circ}X$, A-line의 lifetime은 이론적으로 계산하였고, 온도가 증가함에 따라 lifetime이 증가하였다.

• Archives of Pharmacal Research
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• v.27 no.1
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• pp.19-24
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• 2004

The facile synthesis of a series of 2-(4-hydroxyphenyl)benzofurans (4a-e) is described. The one-pot reaction of 4-substituted phenols with the chloride 1 in the presence of zinc chloride afforded 3-methylthio-2-(4-acetoxyphenyl)benzofurans (2a-e). The compounds 4a-e were obtained from the hydrolysis of 2a-e followed by the desulfurization of the resulting 3-methylthio-2-(4-hydroxyphenyl)benzofurans (3a-e). 5-Methyl-3-p-toluoyl-2 -[4-(3-diethylaminopropoxy)phenyl]benzofuran (7), a $\beta$-amyloid aggregation inhibitor, was synthesized by three steps starting from 4a.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.3
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• pp.233-239
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• 1995

$La_{1/3}NbO_3$ and $La_{1/3}TaO_3$ large single crystal was prepared by the infrared floating zone method and their crystal structure and dielectric properties were investigated from the viewpoint of A - site vacancy. In $La_{1/3}TaO_3$ crystal, the crystal symmetry and approximate lattice constants was tetragonal and a $\approx$ 0.397, b $\approx$ 0.397 and c $\approx$ 0.775 from the nonextinction and the reciprocal lattice point length seen on Weissenberg and Precession photographs. The jump of some $2/3La^{3+}$ ions leads to increase the moving paths due to the generation of new vacancies at middle empty sites and thus this result is confirmed to provoke the dielectric anomaly.

• Electrical & Electronic Materials
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• v.10 no.2
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• pp.141-149
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• 1997

L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ powders were prepared by both GNP(Glycine-Nitrate Process) and solid state reaction method in various of calcination temperature(800-1000.deg. C) and time in air. Also, L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ cathode contacts on YSZ(Yttria-Stabilized Zirconia) substrate were prepared by screen printing and sintering method as a function of sintering temperature(1100-1450.deg. C) in air. Sintering behaviors have been investigated by SEM(Scanning Electron Microscope) and porosity measurement. Compositional and structural characterization were carried out by X-ray diffractometer and ICP AES(Inductively Coupled Plasma-Atomic Emission Spectrometry) analysis. Electrical characterization was carried out by the electrical conductivity with linear 4 point probe method. As the calcination period increased in solid state reaction method, L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ phase increased. Although L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ single phase was obtained only for 48hrs at 1000.deg. C, in GNP method it was easy to get single and ultra-fine L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ powders with submicron particle size at 650.deg. C for 30min. The particle size and thickness of L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ cathode contact by solid state reaction method did not change during the heat treatment, while those by GNP method showed good sintering characteristics because initial powder size fabricated from GNP method is smaller than that fabricated from solid state reaction method. Based on enthalpy change from thermodynamic data and ICP-AES analysis, it was suggested to make cathode contact in composition of (L $a_{0.7}$S $r_{0.3}$)$_{0.91}$ Mn $O_{3}$ which have little second phase (L $a_{2}$Z $r_{2}$ $O_{7}$) for high efficient solid oxide fuel cells applications. As (L $a_{0.7}$S $r_{0.3}$)$_{0.91}$Mn $O_{3}$ cathode contact on YSZ substrate was sintering at 1250.deg. C the temperature that liquid phase sintering did not occur. It was possible to obtain proper cathode contacts with electrical conductivity of 150(S/cm) and porosity content of 30-40%.m) and porosity content of 30-40%.

• Development and Reproduction
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• v.22 no.3
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• pp.263-273
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• 2018

Aquaporin (AQP) 3, a facilitated transporter of water and glycerol, expresses in placenta and fetal membranes, but the detailed localization and function of AQP3 in placenta remain unclear. To elucidate a role of AQP3 in placenta, we defined the expression and cellular localization of AQP3 in placenta and fetal membranes, and investigated the structural and functional differences between wild-type and AQP3 null mice. Gestational sacs were removed during mid-gestational period and amniotic fluid was aspirated for measurements of volume and composition. Fetuses with attached placenta and fetal membranes were weighed and processed for histological assessment. AQP3 strongly expressed in basolateral membrane of visceral yolk sac cells of fetal membrane, the syncytiotrophoblasts of the labyrinthine placenta and fetal nucleated red blood cell membrane. Mice lacking AQP3 did not exhibit a significant defect in differentiation of trophoblast stem cells and normal placentation. However, AQP3 null fetuses were smaller than their control litter mates in spite of a decrease in litter size. The total amniotic fluid volume per gestational sac was reduced, but the amniotic fluid-to-fetal weight ratio was increased in AQP3 null mice compared with wild-type mice. Glycerol, free fatty acid and triglyceride levels in amniotic fluid of AQP3 null mice were significantly reduced, whereas lactate level increased when compared to those of wild-type mice. These results suggest a role for AQP3 in supplying nutrients from yolk sac and maternal blood to developing fetus by facilitating transport of glycerol in addition to water, and its implication for the fetal growth in utero.

• Journal of Periodontal and Implant Science
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• v.24 no.3
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• pp.513-528
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• 1994

배양한 치은섬유아세포와 3T3 세포에서, glycyrrhetinic acid가 cyclosporin A를 처리 세포의 활성에 미치는 영향을 알아보기 위해서 MTT 방법을 이용하여 측정하였다. Cyclosporin A는 $1{\sim}10ng/ml$의 농도에서 인체 치은 섬유아세포와 마우스 3T3 세포 활성을 증가시켰으며, glycyrrhetinic acid는 농도와 비례하게 마우스 3T3 세포의 성장을 억제시켰다. 특히 $25{\mu}g/ml$ 이상의 농도에서는 현저하게 억제시킴을 관찰할 수 있었다. 반면, 인체 치은 섬유아세포에서는 $50{\mu}g/ml$ 이상의 농도에서 조차도 성장을 억제 시키지 않았다. 또한, 마우스 3T3와 인체 치은 섬유아세포에서 일정한 cyclosporin A 농도에 $1-100{\mu}g/ml$의 다양한 농도로 glycyrrhetinic acid를 첨가하였을 때, cyclosporin A 단독으로 처리한 세포에 비하여 유의성 있게 세포의 활성을 억제시켰으며, 특히, $100{\mu}g/ml$의 glycyrrhetinic acid를 첨가하였을 경우 세포활성을 현저하게 억제시켰다. 3T3 세포에 cyclosporin A와 $50{\mu}g/ml$의 glycyrrhetinic acid를 함께 처리한 경우 glycyrrhetinic acid단독처리한 군에 비하여 세포활성에 첨가 효과를 보였으며, 인체 치은 섬유아세포 에서는 같이 처리한 경우 glycyrrhetinic acid단독 처리에 비하여 뚜렷한 억제 효과를 나타내었다. 이러한 상승효과는 1ng/ml 의 cyclosporin A와 $50{\mu}g/ml$ glycyrrhetinic acid를 같이 처리한 군에서 가장 뚜렷하게 관찰되었다. 이러한 결과로, 인체 치은 섬유아세포에 cyclosporin A와 glycyrrhetinic acid를 동에 처리하였을 경우 세포의 활성에 상승 효과가 있음을 알 수 있다.

• International Journal of Molecular Medicine
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• v.43 no.2
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• pp.1105-1113
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• 2019

Epigenetic modifier lysine demethylase 3a (Kdm3a) specifically demethylates mono- and di-methylated ninth lysine of histone 3 and belongs to the Jumonji domain-containing group of demethylases. Kdm3a serves roles during various biological and pathophysiological processes, including spermatogenesis and metabolism, determination of sex, androgen receptor-mediated transcription and embryonic carcinoma cell differentiation. In the present study, physiological functions of Kdm3a were evaluated during embryogenesis of Xenopus laevis. Spatiotemporal expression pattern indicated that kdm3a exhibited its expression from early embryonic stages until tadpole stage, however considerable increase of kdm3a expression was observed during the neurula stage of Xenopus development. Depleting kdm3a using kdm3a antisense morpholino oligonucleotides induced anomalies, including head deformities, small-sized eyes and abnormal pigmentation. Whole-mount in situ hybridization results demonstrated that kdm3a knockdown was associated with defects in neural crest migration. Further, quantitative polymerase chain reaction revealed abnormal expression of neural markers in kdm3a morphants. RNA sequencing of kdm3a morphants indicated that kdm3a was implicated in mesoderm formation, cell adhesion and metabolic processes of embryonic development. In conclusion, the results of the present study indicated that Kdm3a may serve a role in neural development during Xenopus embryogenesis and may be targeted for treatment of developmental disorders. Further investigation is required to elucidate the molecular mechanism underlying the regulation of neural development by Kdm3a.

• Archives of Pharmacal Research
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• v.22 no.2
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• pp.194-201
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• 1999

The reaction of thiocyanoacetamide (1) with ${\alpha},{\beta}$-unsaturated ketones 2a,b resulted in the formation of the corresponding newly synthesized 1(H)-pyridinethione derivatives 3a,b. Compounds 3a,b were used as synthons for the preparation of 2-S-alkyl-, 2-S-acetamidopyridine, thieno[2,3-b]pyridine and pyrazolo[3,4-b]pyridine derivatives via a wide range of reactions with different reagents. The antimicrobial activity of some of the newly synthesized compounds was tested. Compounds 3a, 11a, 15a, and 19a,b were found to be the most active ones.