• Journal of the Korean Vacuum Society
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• v.22 no.2
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• pp.79-85
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• 2013

Rare earth ions, either $Eu^{3+}$ or $Dy^{3+}$-doped $CaMoO_4$ phosphors were synthesized by using the solid-state reaction method. The crystalline structure of all the phosphor powders, irrespective of the type and concentration of activator ions, was found to be a tetragonal system with the main diffraction peak at (112) plane. For $Eu^{3+}$-doped $CaMoO_4$ phosphors, the grain particles showed an increasing tendency and the pebble-like patterns with a very homogeneous size distribution in the range of 0.01~0.10 mol of $Eu^{3+}$ ions concentration, and the excitation spectra were composed of a broad band centered at 311 nm and weak multiline peaked in the range of 360~470 nm. The dominant emission spectrum was the strong red emission centered at 618 nm due to the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ ions. For $Dy^{3+}$-doped $CaMoO_4$ powders, excitation spectra showed a charge transfer band centered at 303 nm and relatively weak bands resulting from the transitions of $Dy^{3+}$ ions and the main yellow emission spectrum was observed at 578 nm, which was assigned to the $^4F_{9/2}{\rightarrow}^7H_{13/2}$ transition of $Dy^{3+}$ ions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.4
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• pp.264-270
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• 2013

$CaMoO_4:Tb^{3+}$ green phosphor powders and thin films were successfully prepared by using the solid-state reaction method and the radio-frequency magnetron sputtering technique, respectively. The crystalline structure of all phosphor powders with different $Tb^{3+}$ ion concentrations was found to be a tetragonal system with the maximum diffraction intensity at $28.58^{\circ}$, while that of the phosphor thin films, irrespective of the type of substrate, was amorphous. As for the phosphor powders, the grain particles showed the chain-like patterns with inhomogeneous size distribution, the excitation spectra were composed of a broad band peaked at 307 nm and two small narrow bands centered at 381 and 492 nm, and the highest green emission spectrum was observed at 0.01 mol of $Tb^{3+}$ ions. As for the phosphor thin films, the average transmittance exceeding 85% was measured in the 400~1,100 nm range and the optical band gap showed a significant dependence on the type of substrate.

• Korean Journal of Materials Research
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• v.7 no.1
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• pp.57-61
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• 1997

Formation of fluorite structure and other related crystal structures in the $Y_{0.8}Ta_{0.2}O_{1.7}$-MO(M=Ba, Sr, Ca and Mg) system has been studied $Ba_2YTaO_6,\;Sr_2YTaO_6$ of cubic perovskite type ordered structure anti $Y_2O_3$ of cubic structure were produced besides the defect fluorite structure when 4 moIob of BaO or SrO was added to $Y_{0.8}Ta_{0.2}O_{1.7}$ When CaO more than 8 nlol"/o was added to $Y_{0.8}Ta_{0.2}O_{1.7}$, monoclinic: $Ca_2YTaO$, and cubic $Y_2O_3$ were pri~tlucecl ;IS this sec:onci phases hesides the main fluorite truc,ture. Smglc phase of fluorite structure \vas 1)roduc:ciI when MgO was added up to 12 mol%, however, MgO appeared as the second phase besides the main fluorire structure when MgO was added more than lti moI0'. Consquently, it is considered rh;it the formation of tluorite structure is related with the formation of the cubic perovskite type ordered structure of $A_2(B'B")O_6$ as well as the cation radii of the additives.additives.

• Korean Journal of Psychosomatic Medicine
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• v.26 no.1
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• pp.59-67
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• 2018

Objectives : The aims of this study were to know the frequency and the nature of cognitive dysfunction in type 2 diabetics, and to reveal influencing variables on it. Methods : From eighty type 2 diabetics (42 males and 38 females), demographic and clinical data were obtained by structured interviews. Cognitive functions were measured using the MMSE-K (Korean Version of the Mini-Mental State Examination) and the Korean Version of the Montreal Cognitive Assessment (MoCA-K) tests. Severity of depression was evaluated by the Korean Version of the Hamilton Depression Rating Scale (K-HDRS). Results : 1) Among eighty type 2 diabetics, 13.75% were below 24 on the MMSE-K, while 38.8% were below 22 on the MoCA-K. 2) The total scores and subtest scores of the MoCA-K including visuospatial/ executive, attention, language, delayed recall and orientation were significantly lower in type 2 diabetics with cognitive dysfunction (N=31) than those without cognitive dysfunction (N=49) (p<0.001, respectively). 3) There were significant difference between type 2 diabetics with and those without cognitive dysfunction in age, education, economic status, body mass index, duration of diabetes, total scores of the K-HDRS, the MMSE-K and the MoCA-K (p<0.05, respectively). 4) The total scores of the MoCA-K had significant correlation with age, education, body mass index, family history of diabetes, duration of diabetes, total scores of the K-HDRS (p<0.05, respectively). 5) The risks of cognitive dysfunction in type 2 diabetics were significantly influenced by sex, education, fasting plasma glucose and depression. Conclusions : The cognitive dysfunction in type 2 diabetics seemed to be related to multiple factors. Therefore, more comprehensive biopsychosocial approaches needed for diagnosis and management of type 2 diabetes.

• 한국ITS학회:학술대회논문집
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• v.2006 no.10
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• pp.236-241
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• 2006

• Bulletin of the Korean Chemical Society
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• v.11 no.1
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• pp.25-28
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• 1990

The superconducting properties have been studied for high-Tc superconductors of the $Bi_{2-x}Mo_xSr_2Ca_2Cu_3O_y$ system (x = 0.03-0.30). The crystal structure is pseudo tetragonal with the average lattice parameters a = 5.38 ${\AA}$, b = 5.44 ${\AA}$ and c = 30.6 ${\AA}$. All samples exhibit superconductivity with Tc offset at 79 K and Tc onset at 90-115 K. The Tc onset point decreases with increasing x, but the Tc offset points are nearly the same for all samples. Scanning electron micrographs show a special growth behavior of the grains with a plate shape. It is suggested that the decrease in Tc onset points with substitution of Mo for Bi is due to the decrease in lattice parameters and to the p-orbital of Mo. It is concluded that Mo does not play a crucial role in the superconducting transition of the $Bi_2Sr_2Ca_2Cu_3O_y$ system.

• Bulletin of the Korean Chemical Society
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• v.27 no.6
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• pp.853-856
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• 2006

Dion-Jacobson phases $CsCa_2Nb_2FeO_9$ and $CsCa_2Nb_2AlO_9$ were reinvestigated by the Rietveld analysis of powder X-ray diffraction (XRD) method, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). These nominal compounds, previously known as the oxygen-deficient layered perovskites with the sequences of $NbO_6-MO_4-NbO_6$ in tripled slab, in fact, were mixed phases of n = 3 Dion-Jacobson phases and impurities such as $Ca_2NbFeO_6$ and $Ca_3Al_2O_6$. The difference of morphology and chemical in-homogeneity between Dion-Jacobson phases and impurities could be clearly identified by scanning electron microscopy with energy-dispersive X-ray spectroscopy. The chemical composition of $CsCa_2Nb_2FeO_9$ was calculated into $Cs_{0.59}Ca_{2.64}Nb_{2.92}Fe_{0.81}$ in small agglomerate crystals and $Cs_{0.95}Ca_{1.97}Nb_{3.08}Fe_{0.15}$ in long plate-like crystals.

• Resources Recycling
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• v.24 no.1
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• pp.21-27
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• 2015

The present study describes the process of producing low oxygen content alloy powder from Ti-6Al-4V and Ti-8Al-1Mo-1V (AMS 4972) alloy scraps using hydrogenation-dehydrogenation (HDH) and deoxidation in solid state (DOSS) processes. Each prepared powder was deoxidized with Ca contact and non-contact method to compare the deoxidation capability. It is known that the non-contact deoxidation method, using Ca vapor above the melting temperature $T_m$ of Ca, has greater deoxidation capability. However, Oxygen contents in Ti-6Al-4V and Ti-8Al-1Mo-1V powder after non-contact deoxidation method were higher than those after contact deoxidation method. Therefore, we investigate the effect of Al - the richest alloy element in theses Ti based metals - on the deoxidation processes.

• Membrane and Water Treatment
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• v.14 no.3
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• pp.121-128
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• 2023

This study introduces a NaOH/Zn-assisted hydrothermal method for the synthesis of zeolites derived from coal ash (CA). A zeolite/Zn adsorbent is successfully prepared by the activation of CA with NaOH and Zn; it is characterized by a high surface area and a negative surface charge.Methylene blue (MB) and methyl orange (MO) are selected as dye pollutants, and their adsorption onto the zeolite/Zn adsorbent is investigated. Results show the high adsorption capacities of MB and MO and that the negative surface charge facilitates electrostatic interactions between the adsorbates and adsorbents. The zeolite/Zn adsorbents shows the selective adsorption of positively charged dye MB via electrostatic interactions between the =NH+ group (positive dipole) and the oxygen functional group of the adsorbents (negative dipole). The selectivity for the positively charged dye is sufficiently high, with the removal efficiency reaching 99.41% within 10 min. By contrast, the negatively charged dye MO exhibits negligible absorption. These findings confirm the role of electrostatic interactions in the adsorption of MB, in addition to the effect of a large surface area. The results of this study are expected to facilitate the development of simple, eco-friendly, and cost-effective zeolite-based adsorptive composites from CA residuals for the selective removal of dye pollutants from CA waste.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3344-3352
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• 2015

The purpose of this study is to investigate the effects of Korean computer-based cognitive rehabilitation program (CoTras) on frontal-executive functions in patients with traumatic brain injury (TBI). This study was performed at C hospital in Changwon, Gyeongsangnam-do, Korea from August 2013 to March 2014. Ten patients with TBI were randomly divided into two groups. The experimental group had been given CoTras once a day, five times a week for four weeks, whereas the control group had performed self-cognitive training under the same conditions. To verify the effect of intervention, the following executive function measures were used: Korean Montreal Cognitive Assessment (K-MoCA), Executive Clock Drawing Test (ECDT), Trail Making Test (TMT), Rey-Complex Figure Test (RCFT). Intervention group showed significant increase in K-MoCA, TMT, RCFT-delayed recall (p<.05). However, control group showed no significant change in any test. There was significant difference of changed scores (post test-pre test) between two groups in K-MoCA, TMT and RCFT-delayed recall (p<.05). This study showed that CoTras is effective to improve frontal-executive functions in patients with traumatic brain injury.