• 한국정보디스플레이학회:학술대회논문집
• /
• 2002.08a
• /
• pp.819-821
• /
• 2002

Photoluminescenc (PL) and low-voltage cathodoluminescence (CL) characteristics of $[xSrTiO_3+(1-x)Li_2TiO_3]:Pr^{3+}$ and $[xSrTiO_3+(1-x)Na_2TiO_3]:Pr^{3+}$ systems were investigated. The red luminescence intensities of these compounds are enhanced remarkably by the incorporation of $Li^+$ or $Na^+$ ion as compared to that of $SrTiO_3:Pr^{3+}$. The enhanced luminescence is speculated to result from both the charge compensation of $Pr^{3+}$ site and oxygen vacancies generated in the lattices by $Li^+$ or $Na^+$ ion.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.1664-1666
• /
• 2000

The structural and microwave properties of Ba($Mg_{1/3}Ta_{2/3})O_3$-Ba($Co_{1/3}Nb_{2/3})O_3$ ceramics were investigated with composition ratio. The specimens were sintered at 1525$^{\circ}C$ for 5 hours in air. All specimens exhibited superlattice reflection planes of (100), (111), (200), (201), and (112). Increasing mole ratio of BCN ceramics, the peak intensity of superstructure reflection plane were decreased, while dielectric constant was slightly increased. The dielectric constant and quality factor of the 0.8BMT-0.2BCN ceramics were 27.51, 103,681 [at 1GHz], respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.318-319
• /
• 2005

본 연구에서는 $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ 혼합 정극활물질로 사용하여 전극을 제작하고 성능을 평가하였다. $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$와 $LiCoO_2$의 혼합비에 따른 충방전 거동 및 임피던스 변화를 측정하였다. 각 조성에서의 초기용량은 160 ~ 170 mAh/g 정도였으며, $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$의 첨가 비율이 증가함에 따라 비용량이 증가하였으나 고율에서의 방전용량은 낮았다.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.11
• /
• pp.1158-1161
• /
• 1997

The potentiometric methods have been used to determined the protonation constants (logKiH) for the synthesized 1,7,13-trioxa-4,10,16-triazacyclooctadecane-N,N',N''-tri(methylacetic acid) [N3O3-tri(methylacetic acid)] and the stability constants (logKML) of the complexes of divalent and trivalent metal ions with the ligand N3O3-tri(methylacetic acid). The protonation constants of N3O3-tri(methylacetic acid) were 9.70 for logK1H, 9.18 for logK2H, 7.27 for logK3H, 3.38 for logK4H, and 2.94 for logK5H. The stability constants for the complexes of divalent metal ions with N3O3-tri(methylacetic acid) were 10.39 for Co2+, 10.68 for Ni2+, 13.45 for Cu2+, and 13.00 for Zn2+. The order of the stability constants for the complexes of the divalent metal ions with N3O3-tri(methylacetic acid) was Co2+ < Ni2+ < Zn2+ < Cu2+. The stability constants for the complexes of trivalent metal ions with N3O3-tri(methylacetic acid) were 16.20 for Ce3+, 16.40 for Eu3+, 16.27 for Gd3+, and 15.80 for Yb3+. The results obtained in this study were compared to those obtained for similar ligands, 1,7-dioxa-4,10,13-triazacyclopentadecane-N,N',N"-tri(methylacetic acid) and 1,7,13-trioxa-4,10,16-triazacyclooctadecane-N,N',N"-triacetic acid, which have been previously reported.

• Applied Biological Chemistry
• /
• v.51 no.2
• /
• pp.136-141
• /
• 2008

The chromatographic separation of organic solvent extracts of liverwort led to the isolation of six compounds. 2-Chromenone (1), 3, 4-dihydroxy-cinnamic acid (2), 3, 3', 4', 5, 7-pentahydroxy-2-phenylchromen-4-one (3), kaemperol-3-O-${\beta}$-D-glucopyranoside (4), 3-[[3-(3,4-Dihydroxyphenyl)-1-oxo-2-propenyl]oxy]-1, 4, 5-trihydroxycyclohexane carboxylic acid (5) and quercetin-3-O-rutinoside (6) were isolated from the methanolic extracts of the all part of Climacium dendroides. Their structure were established by chemical and spectroscopic methods. All compounds were isolated for the first time from this plant Climacium dendroides.

• Restorative Dentistry and Endodontics
• /
• v.31 no.1
• /
• pp.1-10
• /
• 2006

The purpose of this study was to compare the shaping ability of three Ni-Ti file systems used by dental students or the experts and consequently to aid in choosing a proper systems for educational courses of dental students and beginners. Fifty students and ten dentists who have clinical experience over two years prepared 180 simulated root canals in resin blocks with three Ni-Ti systems; $ProFile^{(R)}\;(PF),\;HeroShaper^{(R)}\;(HS),\;K3^{TM}\;(K3)$. After preparation, the Ni-Ti files were evaluated for distortion and canal preparation time was recorded. The images of pre- and post-instrumented canals were scanned and superimposed. Amounts of increased canal widths, deviation, and centering ratio were calculated at apical 1, 3 and 5 mm levels and statistical analysis was performed The results were as follows : 1. HS showed the shortest preparation time and instrumented canal width in K3 was significantly larger than other groups (P<0.05). 2. At 1 and 3mm levels, all groups had outward deviation. In student group, at the 1mm level, PF had the least deviation (P<0.05). 3. In the centering ratio, the PF had the best centering ability compared to the others at 5mm level. At 1 and 3mm levels, HS and PF had better abilities than K3. Student group had better ratio than the expert at 3mm level with PF (P<0.05). Based on the results, it is surmised that the $ProFile^{(R)}$ is the safest and most ideal instrument for students and beginners.

• Bulletin of the Korean Chemical Society
• /
• v.9 no.6
• /
• pp.338-341
• /
• 1988

Two crystal structures of fully dehydrated silver and potassium exchanged zeolite A, stoichiometries of $Ag_{9.3}K_{{2.7}^-}A$ (${\alpha}$ = 12.282(2) ${\AA}$) and $Ag_{10.7}K_{{1.3}^-}{\AA}$ (${\alpha}$ = 12.287(2) A) per unit cell, have been determined from 3-dimensional x-ray diffraction data gathered by counter methods. All structures were solved and refined in the cubic space group Pm3m at 21(1)$^{\circ}C$ . The crystals of $Ag_{9.3}K_{{2.7}^-}A$ and $Ag_{10.7}K_{{1.3}^-}A$ were prepared by flow method using exchange solutions in which mole ratios of $AgNO_3$ and $KNO_3$ were 1:10 and 1:5, respectively, with total concentration of 0.05M. The structures of the dehydrated $Ag_{9.3}K_{{2.7}^-}A$ and $Ag_{10.7}K_{{1.3}^-}A$ were refined to yield the final error indices $R_1$ = 0.037 and $R_2$ = 0.040 with 321 reflections, and $R_1$ = 0.042 and $R_2$ = 0.043 with 371 reflections, repectively, for which I > 3${\sigma}$(I). In both structures, eight $Ag^+$ ions are found nearly at 6-ring centers and each $Ag^+$ ion is nearly in the (1 1 1) plane at its O(3) ligands. The 8-ring sites are preferentially occupied by $K^+$ ions in both structures. 1.3 and 1.7 reduced silver atoms per unit cell were found inside of sodalite units of $Ag_{9.3}K_{{2.7}^-}A$ and that of $Ag_{10.7}K_{{1.3}^-}A$, respectively. These reduced silver species were presumably formed from the reduction of $Ag^+$ ions by oxide ions of residual water molecule or of the zeolite framework. These two crystals may be presented as hexasilver cluster in 21.7% and 28.3% of sodalite unit cells for $Ag_{9.3}K_{{2.7}^-}A$ and $Ag_{10.7}K_{{1.3}^-}A$, repectively.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1561-1564
• /
• 2006

SDI has been developing mobile 3D display for years. For mobile applications, we adapted parallax barrier method. We have developed auto stereoscopic swing 3D display in which people can 3D image in both portrait and landscape mode. Furthermore to increase 3D resolution, we have developed a high resolution 3D display using time division multiplexing parallax barrier method

• Bulletin of the Korean Chemical Society
• /
• v.32 no.3
• /
• pp.1059-1062
• /
• 2011

• Journal of the Korean Chemical Society
• /
• v.37 no.7
• /
• pp.683-686
• /
• 1993