• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1499-1502
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• 2005

Dense $BaMgAl_{10}O_{17}:Eu^{2+}$ phosphor particles with a spherical shape have been synthesized through spray pyrolysis method using basic aluminum nitrate precursor as a spray solution. This $BaMgAl_{10}O_{17}:Eu^{2+}$ particles prepared by the spray pyrolysis have shown the stronger emission intensity compared to the commercially-available $BaMgAl_{10}O_{17}:Eu^{2+}$. However, thermal stability of the BAM:Eu b lue phosphor is very poor due to changing from $Eu^{2+}$ to $Eu^{3+}$ at the thermal process, so brightness of the phosphor decreases. To improve the thermal stability of the dense BAM:Eu phosphor, the spherical BAM:Eu particles were coated with pure $BaMgAl_{10}O_{17}$ layer using the hydrolysis reaction in a solution system. The synthesized powders were characterized by XRD, SEM and PL. On the other hand, the emission properties of the BAM:Eu phosphors coated with $BaMgAl_{10}O_{17}$ layer before and after thermal treatment at $500^{\circ}C$ for 30 min were estimated under VUV excitation. The brightness of the coated phosphor was higher than that of the uncoated phosphor. Also, the coating thickness of BAM layer in the BAM:Eu particles was optimized.

• The Korean Journal of Ceramics
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• v.5 no.4
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• pp.375-378
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• 1999

In tho XRD study of $56ZrF_4 \cdot34BaF_2 \cdot4AIF_3 \cdot(6-x)LaF_3 \cdotxLnF_3$ glassdLn=Ce, Nd, Gd, Th), halo pattern charactarktic fo an amorphous sample appeared. When the halo peak angle ($\theta_p$) was converted into a wavenumber with $Qp=4\pi sinG\pi/\lambda(\lambda$ is the wavolongth of the radialion used), it was found that the Qp values varied almost liuearly with the concentration 01 $LnF_3$. The emissiou spect1.a of $Ce^{3-}$-containing fluoride glasses nnder 273 nm excitation had a peak maximum at ea. 300 nm $(Ce^{3+}$ 5d-4f- transition). The maximal intensity of the fluorescence was observed when the $CeF_3$, content was extremely low (ca. 1 mol%j. DTA measurement revealed tbat these fluoride glasses had two crystallization temperatures. In $56ZrF_4. 34BaF_2. 4NF_3. (6-x)LaF_3 .xNdF_3$ glasses, the actmation energies of crystallization obtained from a Kssinger plot were 1.7 and 5.0 eV for the glass with x=2, and 1.9 and 5.6 eV for the glass with x=4.

• Transactions on Electrical and Electronic Materials
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• v.18 no.6
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• pp.364-369
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• 2017

Double molybdate $NaGd_{1-x}(MoO_4)_2:Ho^{3+}/Yb^{3+}$ phosphors with proper doping concentrations of $Ho^{3+}$ and $Yb^{3+}$ ($x=Ho^{3+}+Yb^{3+}$, $Ho^{3+}=0$ and 0.05, and $Yb^{3+}=0$, 0.35, 0.40, 0.45, and 0.50) were successfully synthesized using the microwave sol-gel method. Well-crystallized particles formed after heat-treatment at $800^{\circ}C$ for 16 h showed fine and homogeneous morphologies with particle sizes of $1{\sim}3{\mu}m$. The spectroscopic properties were examined using photoluminescence emission and Raman spectroscopy. Under excitation at 980 nm, the upconversion doped samples exhibited strong yellow emissions, from the combination of strong emission bands at 545 nm and 655 nm in the green and red spectral regions, respectively. The strong 545 nm emission band in the green region corresponded to the $^5S_2/^5F_4{\rightarrow}^5I_8$ transition in the $Ho^{3+}$ ions, while the strong 655 nm band in the red region appeared because of the $^5F_5{\rightarrow}^5I_8$ transition in the $Ho^{3+}$ ions. The pump power dependence and the Commission Internationale de L'Eclairage chromaticity of the upconversion emission intensity were evaluated in detail.

• Korean Journal of Materials Research
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• v.13 no.12
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• pp.785-790
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• 2003

We have synthesized some phosphors in the system $CaO-Y_2$$O_3$-$Al_2$$O_3$by combinatorial polymerized-complex method. Composition and synthetic temperature of phosphors in the library was screened from the emission intensities of individual samples under VUV excitation. In $Tb^{ 3＋}$-activated $CaO-Y_2$$O_3$-$Al_2$$O_3$, green phosphors showing good intensity were found to be X$O_3$$O_{7}$, CaYA1O$_4$, YA1O$_3$, $Y_3$$Al_{5}$$O_{12}$, $Y_4$$A1_2$$O_{9}$ .

• Korean Journal of Materials Research
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• v.26 no.1
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• pp.29-34
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• 2016

$NaLa_{1-x}{(MoO_4)}_2$:$Ho^{3+}/Yb^{3+}$ phosphors with the correct doping concentrations of $Ho^{3+}$ and $Yb^{3+}$ ($x=Ho^{3+}+Yb^{3+}$, $Ho^{3+}=0.05$ and $Yb^{3+}=0.35$, 0.40, 0.45 and 0.50) were successfully synthesized by the microwave-modified sol-gel method. Well-crystallized particles formed after heat-treatment at $900^{\circ}C$ for 16 h showed a fine and homogeneous morphology with particle sizes of $3-5{\mu}m$. The optical properties were examined using photoluminescence emission and Raman spectroscopy. Under excitation at 980 nm, the UC intensities of the doped samples exhibited strong yellow emissions based on the combination of strong emission bands at 545-nm and 655-nm emission bands in green and red spectral regions, respectively. The strong 545-nm emission band in the green region corresponds to the $^5S_2/^5F_4{\rightarrow}^5I_8$ transition in $Ho^{3+}$ ions, while the strong emission 655-nm band in the red region appears due to the $^5F_5{\rightarrow}^5I_8$ transition in $Ho^{3+}$ ions. Pump power dependence and Commission Internationale de L'Eclairage chromaticity of the upconversion emission intensity were evaluated in detail.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.383-391
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• 2009

Vibrations at different frequencies with a different intensity as well as a pressure pulsation with different parameters are two phenomena which can be observed at different water turbines. Due to the vibration and the pressure pulsation some restrictions of water turbine operation range are applied. Similar problems with the efficiency level in a wide water turbine operation range are the basic problems which are solved for ages. A theoretical and practical solution of the above mentioned problems is very much time and money consuming. The paper describes a new theoretical solution of the excitation and pressure pulsation decrease as well as extension of the operational range with high efficiency level. The new concept to decrease the vibrations and pressure pulsations is based on a heterogeneous runner blade geometry generation. The new concept of the runner geometry design was numerically tested at a low specific speed pump turbine, see Fig. 1, and basic points of the concept are presented in this paper.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.195-198
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• 1990

In order to investigate the radiation effects induced to electrical properties of Biaxially-Oriented Polypropylen film, several observations were carried out to the sample irradiated to various dose by $Co^{60}-{\gamma}$ ray, on the characteristics of TSC spectra measuered as a function of electric field applied to a sample of 15[ ${\mu}m$] thick. The TSC spectra observed in the temperature range of $153{\sim}403[K]$ with the electric field of intensity $10{\sim}60$ [MV/m], have shown two of the distinguished peak such as ${\beta}$, ${\alpha}$, each of which appeared at $-5{\sim}20$ [ $^{\circ}C$] and 90 [ $^{\circ}C$] respectively. As the conclusions, obtained from the studies, the origin of ${\alpha}$ peak in TSC seems to be attributed by thermal excitation of ions trapped with $0.4{\sim}0.8[eV]$ deep, at the defects formed by $Co^{60}-{\gamma}$ irradiation in a crystaline region. The origin of ${\beta}$ peak was regarded as the depolarization process of "OH" or "CO" dipole with the activation energy of $0.4{\sim}0.6[eV]$ in an amorphous region.

• Korean Journal of Animal Reproduction
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• v.17 no.4
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• pp.279-285
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• 1994

The objective of the present study was to characterize the cell cycles of granulosa cell populations during follicular maturation in cattle by using flow cytometer. Granulosa cells were isolated from bovine preovulatory antral follicles of F1(>10mm), F2(5~20mm), F3(3~4mm) and F4(1~2mm) diameter and fixed and stained with fluorochromes that selectively bine to DNA. Flow cytometer equipped with a laser excitation system was used to analyze the intensity of fluorescence from stained cells. Forward angle light-scatter(FSC) and 90$^{\circ}$light-scatter(SSC) signals were adopted to measure the size and the granularity of granulosa cells. As a results of FSC/SSC analysis, granulosa cell populations(G1 phase of cell cycle) from each follicle were relatively regular in size and granularity, regardless of follicular size. However, their distribution in granularity was greater than that in size. Most of granulosa cell populations collected from each follicle were distributed in G0/G1, S and G2/M phases. As the follicles approached to ovulation the percentage of cells in the proliferative phases of cell cycle (S and G2/M) decreased significantly, but there was a concomitant increase in the percentage of granulosa cells in G1 phase. Therefore, these data indicate the proportion of main populations to cell cycle of granulosa cells may be changed from proliferative phase to G1 phase during follicular maturation in cattle.

• Analytical Science and Technology
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• v.8 no.3
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• pp.359-364
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• 1995

Urinary dipeptidase(Udpase) was assayed by fluorometric analysis of NADH which was produced from an indicator enzyme, L-alanine dehydrogenase. The reaction mixture was consisted of a dipeptide(L-ala-L-ala), ${\beta}-NAD^+$, L-alanine dehydrogenase in 12.5 mM sodium carbonate buffer, pH 9.0, and urinary dipeptidase which initiated the reaction. The fluorescence intensity of NADH was measured as a function of time with the excitation wavelength at 340nm and emission at 460nm. Comparison of this fluorometric method with the conventional spectrophotometric method utilizing glycyldehydrophenylalanine(Gdp) as substrate provided the correlation coefficient of 0.996 and increased the sensitivity more than ten times.

• Archives of Pharmacal Research
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• v.27 no.5
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• pp.562-569
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• 2004

Self-assembling nanospheres of hydrophobized pullulan have been developed. Pullulan acetate (PA), as hydrophobized pullulan, was synthesized by acetylation. Carboxymethylated poly(ethylene-glycol) (CMPEG) was introduced into pullulan acetate (PA) through a coupling reaction using N, N'-dicyclohexyl carbodiimide (DCC). A synthesized PA-PEG-PA (abbreviated as PEP) conjugate was confirmed by Fourier transform-infrared (FT-IR) spectroscopy. Since PEP conjugates have amphiphilic characteristics in aqueous solution, polymeric nanoparticles of PEP conjugates were prepared using a simple dialysis method in water. From the analysis of fluorescence excitation spectra primarily, the critical association concentration (CAC) of this conjugate was found to be 0.0063 g/L. Observations by scanning electron microscopy (SEM) showed the spherical morphologies of the PEP nanoparticles. The particle size distribution of the PEP conjugates was determined using photon correlation spectroscopy (PCS) and the intensity-average particle size was 193.3 ${\pm}$ 13.53 nm with a unimodal distribution. Clonazepam (CNZ), as a model drug, was easy to entrap into polymeric nanoparticles of the PEP conjugates. The drug release behavior was mainly diffusion controlled from the core portion.