• Current Photovoltaic Research
• /
• v.2 no.2
• /
• pp.53-58
• /
• 2014

$Tb^{3+}$ - or $Ce^{3+}$-doped $LaBO_3$ phosphors were synthesized by a solid-state reaction process with different concentrations of activator ions. The XRD spectra showed the monoclinic $LaBO_3$ pattern with the main peak occurring at (014) plane, irrespective of the kind of activator ions. The crystallite size was determined by using the Scherrer formula, and the maximum was obtained with an activator concentration of 0.05 mol for both phosphors. The emission spectra of $LaBO_3$ phosphors doped with $Tb^{3+}$ ions under excitation at 269 nm exhibited three major emission bands at 488, 544, and 587 nm. The strongest emission was green at 544 nm owing to the $^5D_4-^7F_5$ transition at a $Tb^{3+}$ ion concentration of 0.05 mol. For the $Ce^{3+}$-doped $LaBO_3$ phosphors, one strong blue band centered at 469 nm and weak multipeaks were observed. These results suggest that the optimum green and blue emission can be realized by controlling the concentration and type of activator ions incorporated in the host crystal.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.14 no.5
• /
• pp.22-28
• /
• 1977

This is a design and analysis of the D.C. highly stabilized power source. This appratus has 10**-7 order of the voltage regulation and 40V, 1.5A, continuosly variable D.C. output. Authors inspected the effect of the OP Amp, FET and the load circuit to the stationary and transient characteristics of the apparatus. Authors found that it is a useful method for high performance of the stabilized power source to utilize IC OP Amp and FET as the elements of it.

• Journal of the Korean Vacuum Society
• /
• v.7 no.2
• /
• pp.112-117
• /
• 1998

TiN has been investigated as a good candidate for a diffusion barrier of Cu. Therefore, in this study, the grain boundary diffusion of Cu in TiN film was investigated by X-ray photoelectron spectroscopy(XPS). In general, TiN has a columnar grain structure. In the relatively lower temperature, less than 1/3 of the melting point, it was observed that Cu diffused into TiN mainly along the grain boundaries of TiN. The grain size of TiN was measured by atomic force microscope (AFM). In order to estimate the grain boundary diffusion constants, we used the modified surface accumulation method. The activation energy, $Q_b$ was 0.23 eV, and the diffusivity, $D_{bo}$ was $5.5\times10^{-12{\textrm{cm}^2$/sec.

• Journal of Powder Materials
• /
• v.23 no.2
• /
• pp.108-111
• /
• 2016

$Y_2O_3-H_3BO_3:Eu^{3+}$ powders are synthesized using a mechanical alloying method, and their photoluminescence (PL) properties are investigated through luminescence spectrophotometry. For samples milled for 300 min, some $Y_2O_3$ peaks ([222], [440], and [622]) and amorphous formations are observed. The 300-min-milled mixture annealed at $800^{\circ}C$ for 1 h with Eu = 8 mol% has the strongest PL intensity at every temperature increase of $100^{\circ}C$ (increasing from 700 to $1200^{\circ}C$ in $100^{\circ}C$ increments). PL peaks of the powder mixture, as excited by a xenon discharge lamp (20 kW) at 240 nm, are detected at approximately 592 nm (orange light, $^5D_o{\rightarrow}^7F_1$), 613 nm, 628 nm (red light, $^5D_o{\rightarrow}^7F_2$), and 650 nm. The PL intensity of powder mixtures milled for 120 min is generally lower than that of powder mixtures milled for 300 min under the same conditions. PL peaks due to $YBO_3$ and $Y_2O_3$ are observed for 300-min-milled $Y_2O_3-H_3BO_3$ with Eu = 8 mol% after annealing at $800^{\circ}C$ for 1 h.

• Korean Journal of Poultry Science
• /
• v.37 no.4
• /
• pp.347-354
• /
• 2010

The current work was carried out to investigate the effect of crossbred Korean native chickens (KNC) on performance and carcass ratio. Seven hundred twenty 1-d-old chicks were divided into groups by strain (A, B, C and D) and sex (male and female). Strains were A) (KNC egg-meat type C strains $\times$ KNC meat type S strains) $\times$ KNC meat type H strains, B) (KNC egg-meat type C strains $\times$ KNC meat type H strains) $\times$ KNC meat type S strains, C) (KNC native R strains $\times$ KNC meat type S strains) $\times$ KNC meat type H strains and D) (KNC native L strains $\times$ KNC meat type H strains $\times$ Ross broiler. Experimental diets consisted of 3 phases such as starter(0~5 weeks; CP 20.0%, ME 3,050 kcal/kg), earlier (5~8 weeks; CP 18.0%, ME 3,100 kcal/kg) and finisher (8~12 weeks; CP 16.0%, ME 3,150 kcal/kg). Body weight (BW) and feed intake (FI) was measured every week and carcass ratio(CR) was calculated at 5 and 10 week after starting experiment. There was no difference in BW among strains until 5 weeks (P>0.05), however D strain resulted in a higher BW after 5 weeks (P<0.05). Body weight gain (BWG) and FI in D strain were also significant higher compared to the other strains for all periods. However, D strains showed the lowest (P<0.05) fee conversion ratio (FCR). The other strains except D showed a similar BW, BWG, FI and FCR among strains. In addition, there were no differences in carcass weight (CW) and carcass ratio (CR) among strains at 5 weeks, however D strain showed higher CW and CR at 10 weeks. These results suggested the basic data that needed to develope the new strains.

• Archives of Pharmacal Research
• /
• v.29 no.1
• /
• pp.40-45
• /
• 2006

Several diacetoxy acetal analogues have been synthesized from santonin and assessed for their ability of inducing or enhancing the differentiation of human HL-60 leukemia cells. The compounds themselves had little effect on HL-60 cell differentiation. However, three analogues, 2a, 3a, and 5b, synergistically enhanced 1,25-dihydroxyvitamin $D_3[1,25-(OH)_2D_3]-induced$ HL-60 cell differentiation when combined with 5 nM of dihydroxyvitamin $D_3[1,25(OH)_2O_3]$, a well-known differentiation inducer. Especially, the compound 5b profoundly enhanced the $1,25-(OH)2O_3]-induced$ HL-60 cell differentiation.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07b
• /
• pp.1514-1517
• /
• 2005

The $(Y,Gd)BO_3:Eu^{3+}$ phosphor was made by coprecipitation method. The precipitated powders were amorphous. The value of pH in the process of coprecipitation was critical for the luminescence of phosphors. The particle size and morphology were influenced by pH value. The lower calcination temperature and hydrothermal synthesis leads to the distortion of lattices. The distorted lattices changed the symmetry of $Eu^{3+}$ site. The broken inversion symmetry in the distorted lattice caused the increased emission of $^5D_0{\rightarrow}^7D_2$ transition.

• Journal of the KSME
• /
• v.16 no.2
• /
• pp.84-91
• /
• 1976

An experimental investigation of the natural circulating boiling flow characteristic in three cases of annulus with different outer diameter, and the effect of annular gap size on the burnout behavior is presented. The experimental work was conducted for each case of test section at system pressure of $1kg/cm^2$ and inlet subcooling $0-20^{\circ}C$ in the full range of throttling ratio. As the result, the following facts were found. 1) With the increase of ${\Delta}T_{sub}$, $D_{2}$ and A/A_{o}$, $q_{BO}$ increases on the whole, and with the decrease of ${\Delta}T_{sub}$ and $D_{2}$, hydrodynamic instability is accelerated to happen prematually. 2)With the increase of ${\Delta}T_{sub}$, $D_{2}$ and A/A_{o}$ burnout characteristic shows the high velocitylow quality burnout, and with the decrease, low-velocity-high quality burnout. 3)With the decrease of A/A_{o}$, hyddrodynamic instability is singnificantly restrained and the difference of $q_{BO}$ in each $D_2$ under same condition is gradually reduced, finally converging into $1.9{\times}10^{5}kcal/m^{2}-hr$.

• Journal of the Korean Society of Radiology
• /
• v.8 no.7
• /
• pp.455-459
• /
• 2014

We grew the $Li_6Gd(BO_3)_3:Ce^{3+}$ scintillator and determined the scintillation and thermoluminescence properties for X-rays. The emission spectrum of $Li_6Gd(BO_3)_3:Ce^{3+}$ is located in the range of 370~500 nm, peaking at 423 nm an 455 nm, due to the $4f{\rightarrow}5d$ transition of $Ce^{3+}$ ions. The fluorescence decay time of the crystal is composed three components. The fast component is 60 ns (25%), the intermediate component is 787 ns (29%) and the slow component is $5.9{\mu}s$ (46%) of the crystal. The after-glow is caused by the electron and hole traps in the crystal lattice. We determined physical parameters of the traps in the crystal. The thermoluminescence trap are composed two traps. The determined activation energy (E), kinetic order (m) and frequency factor (s) of the first trap are 0.65 eV, 1.01 and $6.9{\times}10^8s^{-1}$. And, the determined activation energy, kinetic order and frequency factor of the second trap are 0.96 eV, 1.79 and $3.1{\times}10^{12 }s^{-1}$, respectively.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2007.05a
• /
• pp.149.2-149.2
• /
• 2007