• Journal of the Korean Graphic Arts Communication Society
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• v.29 no.2
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• pp.33-44
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• 2011

The inorganic powder EL lamp was made by screen printing technique with a phosphor ink and a dielectric ink. The thickness of a phosphor ink layer and a dielectric ink layer is $35{\mu}m$ and $54{\mu}m$ respectively. A increasing ratio of the luminance of inorganic powder EL lamp to be a 1P1PD-phosphor ink layer in which increased voltage at constant frequency is higher 12% than when increased frequency at constant voltage. It is higher 57% than when increased frequency at constant voltage that the rate of increase of the luminance of inorganic powder EL lamp to be a 2PD-phosphor ink layer in which increased voltage at constant frequency. Finally, when increased voltage at constant frequency, a increasing ratio of the luminance of inorganic powder EL lamp to be a 2PD-phosphor ink layer is higher about 40% than that to be a 1P1PD-phosphor ink layer.

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.1
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• pp.38-41
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• 2010

Compared to conventional molding technology, the color uniformity of light direction emitted from LED is improved with PCB type lead frame technology in which metal thin film is used and transfer molding technology which makes the density of phosphor uniform by manufacturing high density LED lamp. The light efficiency and the color uniformity of the LED are improved by molding the phosphor layer outside of chip and controlling the thickness of the phosphor layer. CIE x,y difference of LED in major axis is also improved uniformly from 0 to 90 degrees.

• Journal of radiological science and technology
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• v.16 no.1
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• pp.41-55
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• 1993

Recently, various screen film system have been introduced in diagnostic radiology. There are two kinds of screen film system : blue emitting $CaWO_4$ screen has been largely used in these days. However, it tends to be changed to use green emitting $Gd_2O_2S$ : Tb screen. In this study, photographic characteristics of $CaWO_4$ and $Gd_2O_2S$ : Tb screen were investigated with luminescence, spectroscopy. The morphology of $CaWO_4$ and $Gd_2O_2S$ : Tb were also observed by using scanning electron microscope. The result obtained were as follows : 1. There was small difference in the thickness of phosphor layers for the front and back screen of blue emitting system, but little difference in those of green emitting system. 2. There was no difference in the size of phosphor particles between the front and back screen for each screen. However, the particle size was different for the various kinds of screens. 3. The shape of phosphor particle was round with many faces for all the screens. 4. In the exposure of X-ray with the same intensity, luminescent intensity of a green emitting system was $6{\sim}7$ times larger than that of a blue emitting system. 5. The thickness of phosphor layers does not affect on the sensitivity of the screens exposed by X-ray.

• Journal of Powder Materials
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• v.25 no.1
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• pp.12-18
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• 2018

Cost-effective functional phosphor nanoparticles are prepared by introducing low-cost $SiO_2$ spheres to rare-earth phosphor ($YVO_4:Eu^{3+}$, $YVO_4:Er^{3+}$, and $YVO_4:Nd^{3+}$) shells using a sol-gel synthetic method. These functional nanoparticles are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and general photoluminescence spectra. The $SiO_2$ sphere occupying the interior of the conventional phosphor is advantageous in significantly reducing the cost of expensive rare-earth phosphor nanoparticles. The sol-gel process facilitates the core-shell structure formation; the rare-earth shell phosphor has strong interactions with chelating agents on the surfaces of $SiO_2$ nanoparticles and thus forms layers of several nanometers in thickness. The photoluminescence wavelength is simply tuned by replacing the active materials of $Eu^{3+}$, $Er^{3+}$, and $Nd^{3+}$. Moreover, the photoluminescent properties of the core-shell nanoparticles can be optimized by manipulating the specific contents of active materials in the phosphors. Our simple approach substitutes low-cost $SiO_2$ for expensive rare-earth-based phosphor materials to realize cost-effective phosphor nanoparticles for various applications.

• Journal of the Korean Ceramic Society
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• v.51 no.6
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• pp.533-538
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• 2014

Today, silicon and epoxy resin are used as materials of conversion lenses for white LEDs on the basis of their good bonding and transparency in LED packages. But these materials give rise to long-term performance problems such as reaction with water, yellowing transition, and shrinkage by heat. These problems are major factors underlying performance deterioration of LEDs. In this study, in order to address these problems, we fabricated a conversion lenses using glass, which has good chemical durability and is stable to heat. The fabricated conversion lenses were applied to a remote phosphor type. In this experiment, the conversion lens for white LED was coated on a glass substrate by a screen printing method using paste. The thickness of the coated conversion lens was controlled during 2 or 3 iterations of coating. The conversion lens fabricated under high heat treatment temperature and with a thin coating showed higher luminance efficiency and CCT closer to white light than fabricated lenses under low heat treatment temperature or a thick coating. The conversion lens with $32{\mu}m$ coating thickness showed the best optical properties: the measured values of the CCT, CRI, and luminance efficiency were 4468 K, 68, and 142.22 lm/w in 20 wt% glass frit, 80 wt% phosphor with sintering at $800^{\circ}C$.

• Journal of the Korean Graphic Arts Communication Society
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• v.30 no.1
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• pp.47-58
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• 2012

The inorganic powder EL lamp was made by screen printing technique with a phosphor ink and a dielectric ink. Value of color coordinates X and Y increased under the condition of supplying driving power to the inorganic powder EL lamp and changing voltage with constant frequency. When frequency was changed under the constant voltage, value of color coordinates X and Y were decreased with increasing frequency. However, level of change of color coordinates X was different from color coordinates Y. When voltage was increased under constant frequency, changing degree of color coordinates X and Y shows similarity. But under the constant voltage with changing frequency, color coordinates X and Y were differently changed that degree of change of color coordinates Y showed five times more than that of color coordinates X. As increasing thickness of phosphor ink and dielectric ink, level of voltage and frequency, color coordinates X and Y were slightly changed. According to the thickness of phosphor ink and dielectric ink, and level of voltage and frequency, color coordinate of color light was changed. Frequency was most important element influencing on the change of color coordinate.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1783-1785
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• 1999

In this paper, we apply V-Q Lissajoucs' figure for observation of a V-Q (Voltage-Charge) hysteresis loop at interface between phosphor and insulation layer in P-ELDz which are a simple structure and the back lighting of LCDs (Liquid Crystal Display). In V-Q Lissajous' figure, we measured a change of hysteresis loop according to the thickness of Insulation and phosphor layer. From experiment result, we will be obtained a optimum thickness of insulation with comparing the correlation of a V-L (Voltage-Luminance) and V-Q hysteresis loop.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2001.11a
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• pp.147-147
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• 2001

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.79-82
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• 2009

This work presents a novel lighting technology based on a YAG:$Ce^{3+}$ phosphor converter with micro line lenticular structure, to accompany an array of bare LED chips on a board. This technology is especially effective in TFT-LCD backlight applications as it offers the advantages of high light radiation efficiency, low color deviation, uniform luminance distribution and compact backlight thickness. Additionally, the proposed configuration is low-cost, can be manufactured quickly, and can be mass-produced economically.