• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.302-308
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• 2009

This study investigated the production of hydrogen over Ga (1.0, 2.0, and 5.0 mol%)-$TiO_2$ photocatalysts prepared by a solvothermal method. The absorption band was slightly blue-shifted upon the incorporation of the gallium ions, but the intensity of the photoluminescence (PL) curves of Ga-incorporated $TiO_2$s was distinguishably smaller, with the smallest case being the 2.0 mol% Ga-$TiO_2$, which was related to the recombination between the excited electrons and holes. $H_2$ evolution from photo splitting of water over Ga-incorporated $TiO_2$ in the liquid system was enhanced, compared to that over pure $TiO_2$; particularly, the production of 5.6 mL of $H_2$ gas after 8 h when 1.5 g of the 2.0 mol% Ga-incorporated $TiO_2$ was used.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.461-462
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• 2008

$BaMgAl_{10}O_{17}$:Mn, $Eu^{2+}$ green phosphors has been synthesized by the solid state reaction. Green phosphors of nano-size were manufactured in short time by shake method. which were easily manufactured respectively general method. Green phosphors of nano size were control additive, size of $ZrO_3$ ball, shake time and weight of ball in toluene. In result that green phosphors were obtained particle size of 140nm~150nm. The characteristics of fired samples were obtained by 365nm and 380nm excitation source under ultraviolet. In result that the highest PL intensity were observed in wavelength of 365nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.172-172
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• 2008

By thermal evaporation method, well-aligned ZnO nanowires were synthesized on sapphire substrate at $1000^{\circ}C$ with different oxygen flow rate by using pure ZnO powder (99.999 %). The as-synthesized ZnO nanowires were characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The well-aligned nanowires are single crystalline in nature and perpendicularly grown along the c-axis. Also the growth rate of nanowires, such as diameter and length, had a tendency to increase as oxygen flow rate increased. Based on the PL measurement of ZnO nanowires, we found that the near band edge of emission redshifted with the increasing intensity of the defect-related green emission in proportion to the increase of oxygen flow rate. "This research was supported by the Korea Research Foundation Grant funded by the Korean Government(MOEHRD)" (The Regional Research Universities Program/Chungbuk BIT Research-Oriented University Consortium).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.91-95
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• 1999

PED용 형광체로 사용되는 ZnCa$_2$O$_4$를 Clycine Nitrate Process로 합성하여 고상 반응법으로 합성한 ZnCa$_2$O$_4$ 분말과 비교 분석하였다. 또한 Glycine Nitrate Process로 제조시 Mn의 doping 농도를 변화시키면서 각각의 조성비에 따른 발광특성을 알아보았다. TGA 측정 결과 GNP법으로 합성된 ZnCa$_2$O$_4$ 의 경우 약 40$0^{\circ}C$ 이상에서 무게감량의 변화가 없었으며, XRD 상분석 결과 연소반응 후 이미 상형성이 이루어짐을 알 수 있었다. PL측정을 결과 GNP(GIycine Nitrate Process)로 제조된 ZnCa$_2$O$_4$분말의 발광효율이 고상 반응법으로 제조된 분말보다 우수하였으며, 균일하고 비표면적이 큰 단일상임이 관찰되었고, 더 작은 에너지와 시간으로 제조할 수 있는 장점이 있었다

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.7
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• pp.317-326
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• 2002

In this paper, a methodology for optimal PI supplementary controller using the modified genetic algorithm has been proposed to the oscillation damping in HDVC transmission system. These study processes are summarized as the formulation for load flow calculation in HVDC transmission system with SVC, the investigations on the basic control in HVDC system, the mathematical modeling for dynamic characteristics analyses, and the optimal design of MGA based PI controller generation the supplementary control signal of SVC. Its properties were verified through a series of computer simulations including dynamic stability. It means that the application of MGA-PI controller in HVDC transmission system can contribute the propriety to the improvement of the stability in HVDC transmission system and the design of MGA-OI controller has been proved indispensible when applied to HVDC transmission system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.601-604
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• 1999

Electroluminescence(EL) devices based on organic thin films have attracted lots of interests in large-area light-emitting display. Recently, many EL researcher have interested a new emissive organic material. In this study, light-emitting organic electroluminescent devices were fabricated using Langmuir-Blodgett(LB) technique with new emissive organic material. This new emissive organic material were synthesis by our teams and we called PECCP [poly(3,6-N-2ethylhexyl carbazoly cyanoterephthalidene)] which has strong electron donor group and electron acceptor group in main chain repeat unit. This material has good solubility in common organic solvent such as chloroform. THF, etc. and has a good stability in air. In here, the new emissive material is applied to Langmuir-Blodgett(LB) method because our new material has a good stability in air. Optimum conditions of film deposition were examined by a surface pressure-area( $\pi$ -A) isotherms with various factors. The LB film were deposited on a indium Tin Oxide(ITO) glass. We were investigated by measuring current-voltage(I-V) characteristics. Also we were measured the UV/visible absorption at about 410nm and PL spectrum at about 530nm. We are attempt to the electroluminescence device properties of the new emissive material by Langmuir-Blodgett(LB) technique.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.5
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• pp.419-424
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• 2009

ZnO films doped with different contents of indium ($0.1{\sim}10$ at.%) were deposited on Si (111) substrate by Pulsed Laser Deposition (PLD). The structural, electrical and optical properties of the films were investigated using XRD, AFM, Hall and PL measurement. Results showed that un-doped ZnO film had (002) plane as the c-axis orientated growth, whereas indium doped ZnO films exhibited the peak of (002) and the weak (101) plane. In addition, in the indium doped ZnO films, the electron concentration is ten times higher than that of un-doped ZnO film, while the resistivity is ten times lower than that of un-doped ZnO film. The indium doped ZnO films have UV emission about 380 nm and show a red shift with increasing contents of indium. The I-V curve of the fabricated diode show the typical diode characteristics and have the turn on voltage of about 2 V.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1077-1081
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• 2014

Polyacrylamide (PAM) -HgS nanocomposites were successfully prepared in polyacrylamide (PAM) matrix. From TEM and XRD characterizations, the synthesized HgS nanocrystals were chain-like spherical in shape with a diameter of about 40-60 nm and high crystalline quality. The quantum-confined effect of HgS nanocrystals was confirmed by UV-vis diffuse reflection spectra. The optical properties of products were investigated by using photoluminescence (PL) spectra, which showed that HgS nanocrystals exhibited good optical properties with maximum emission peak at about 640 and 650 nm at different reaction temperatures. The interaction of HgS nanocrystals with PAM was studied through FT-IR spectroscopy and TG analysis, which suggested that $Hg^{2+}$ could interact with functional groups of PAM. The experimental results indicated that PAM not only induced nucleation, but also inhibited further growth of HgS crystals and play an important role in the formation of PAM/HgS nanocomposites. In addition, the possible mechanism of HgS nanoparticles growth in PAM solution was also discussed.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.22 no.4
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• pp.307-313
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• 2011

Objectives : This study explored the clinical differences in attention-deficit hyperactivity disorder (ADHD) patients with and without developmental coordination disorder (DCD). Methods : Participants were 49 children and adolescents with ages between 6 and 18 years. These subjects were placed into 2 groups: ADHD without DCD (24) and ADHD with DCD (25). We used several evaluation tools on both groups: the Affective Disorders and Schizophrenia-Present and Lifetime Version- Korean Version (K-SADS-PL), Wechsler Intelligence Scale for Children-III (WISC-IIII), Child Behavior Check List (CBCL), Korean Personality Rating Scale for Children (K-PRC), and Bruininks-Osretsky Test of Motor (BOT-2). Results : Patients with both ADHD and DCD had a lower performance intelligence quotient and more internal and external behavioral symptoms than patients with ADHD but not DCD. It is possible that patients with ADHD and motor coordination problems should be noticed earlier and given intensive treatment.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.5
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• pp.188-192
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• 2015

Gemological and spectroscopic properties of HPHT synthetic diamonds from New Diamond Technology (NDT) company in St. Petersburg (Russia) were examined. Their color (colorless, near-colorless with some boron and Fancy blue with high boron content) and clarity ($VVS-SI_1$) grades were comparable to those of top natural diamonds. NDT synthetic diamonds fluoresced and phosphoresced blue or orange under SWUV light. Photoluminescence spectra revealed H3 center with very small intensity and NV centers. The intensity of H3 in NDT synthetic diamond has very weak in comparison with natural one. Using a combination of gemological and spectroscopic tests, gem-quality synthetic diamonds from NDT can be distinguished from natural diamonds of similar quality.