• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2512-2518
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• 2014

The praseodymium-doped $TiO_2$ photocatalyst samples, which could degrade methyl orange under UV irradiation, were prepared by sol-microwave method for improving the photocatalytic activity of $TiO_2$. The resulting materials were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectra, Fourier transform infrared spectra (FTIR) and Ultraviolet-visible diffuse reflectance spectra (UV-vis DRS). It was found Pr doping retarded the growth of crystalline size and the phase transformation from anatase to rutile, and narrowed the band gap energy. Praseodymium doping brought about remarkable improvement in the photoactivity. The optimal dopant amount of Pr was 2% by molar of cement and the calcination temperature was $500^{\circ}C$ for the best photocatalytic activity. The improvement of photocatalytic activity was ascribed to the occurrence of lattice distortion and the effective containment of the recombination of the electron-hole by $Pr^{3+}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.312-316
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• 1999

I-V characteristics of Praseodymium-based ZnO varistor doped with $Nd_2O_3$ in the range 0.0-2.0mol% sintered at 130$0^{\circ}C$ and 135$0^{\circ}C$ were investigated. In the all sides, ZnO varistors sintered at $1300^{\circ}C$ exhibited much better varistor characteristics than that at 135$0^{\circ}C$. All ZnO varistors doped with $Nd_2O_3$ sintered at $1300^{\circ}C$ exhibited good varistor characteristics but particularly ZnO varistor doped with l.Omol% $Nd_2O_3$ exhibited the best characteristics, which the nonlinear is 65.2 and the leakage current is 4.5pA. It is estimated that ZnO varistor doped with l.Omol% $Nd_2O_3$ will begin to be sufficiently used as basic composition to fabricate a good varistor.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.3
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• pp.459-463
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• 2002

We studied the effect of gain recovery at the optical fiber amplifier by the input pulse trains We also theoretically analyzed the limitation of the saturation and recovery time for the PDFA(Praseodymium-Doped Fiber Amplifier) which has the spectral gain at 1.3${\mu}{\textrm}{m}$ band. We can predict the interval between the pulse train, pump power, and the effect of the saturation and recovery time which is affected to the amplification of the optical pulse.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.505-508
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• 2002

We studied the effect of gain recovery at the optical fiber amplifier by the input pulse trains. We also theoretically analyzed the limitation of the saturation and recovery time for the PDFA(Praseodymium-Doped Fiber Amplifier) which has the spectral gain at 1.3${\mu}{\textrm}{m}$ band. We can predict the interval between the pulse train, pump power, and the effect of the saturation and recovery time which is affected to the amplification of the optical pulse.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.10
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• pp.896-901
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• 2005

The microstructure and electrical properties of praseodymium-based zinc oxide varistors were investigated at various cobalt oxide contents in the range of $0.5{\~}5.0 mol\%$. The ceramic density increased in the range of $5.25{\~}5.55 g/cm^3$ with increasing cobalt oxide content. The varistor doped with cobalt oxide of $1.0 mol\%$ exhibited the highest nonlinearity, with 66.6 in nonlinear exponent and 1.2 $\mu$A in leakage current. The donor concentration, density of interface states, and tamer height were in the range of $(1.06{\~}1.69){\times}10^{18}/cm^3$, $(3.11 {\~}3.56){\times}10^{12}/cm^2$, and 0.80${\~}$1.07 eV, respectively.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.78-80
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• 2001

DC accelerating aging characteristics of praseodymium-based ZnO varistors doped with $Dy_2O_3$ were investigated with sintering time. The varistor sintered for 1h exhibited the highest nonlinearity, with a nonlinear exponent of 66.61 and a leakage current of $1.16{\mu}A$, whereas they did not exhibit relatively high stability. The varistor sintered for 2h having nonlinear exponent of 54.81 and leakage current of $2.52{\mu}A$ showed very excellent stability, which the variation rates of varistor voltage, nonlinear exponent, and leakage current are -1.19%, -4.00%, and +75.79% for 2h, under DC accelerated aging stress, such as ($0.85\;V_{1mA}/115^{\circ}C$/24h)+($0.90\;V_{1mA}/120^{\circ}C$/24h)+($0.95\;V_{1mA}/125^{\circ}C$/24h)+($0.95\;V_{1mA}/150^{\circ}C$/24h).

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.44-45
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• 2002

1.3$mu extrm{m}$ 대역에서 증폭특성을 갖는 광섬유 증폭기인 Praseodymium-doped fiber amplifier(PDFA)는 Ohishi 등에 의해서 처음으로 제안되었다. 수십 nm의 이득 대역폭을 갖고, 30dB 이상의 높은 신호 이득을 갖는 PDFA는 1.3～l.6$\mu\textrm{m}$에 이르는 광대역 WDM을 위한 중요한 증폭기로 사용되고 있다. 최근에는 1.3~1.6$\mu\textrm{m}$에 이르는 광대역 WDM을 위해 광섬유 증폭기의 이득을 shift시키고, 이득 평탄화를 위한 많은 연구가 진해되어 지고 있으나, 광섬유 내에서 초고속의 광 신호를 증폭 시 발생할 수 있는 상호채널 간섭, 상호변조 왜곡, bit rate 높은 펄스열의 증폭 시 발생할 수 있는 이득소멸(gain depletion)과 이득회복(gain recovery) 등과 같은 과도응답 현상에 관한 연구는 충분히 보고되어있지 않다. (중략)

• Journal of the Korean Ceramic Society
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• v.47 no.3
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• pp.249-255
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• 2010

To investigate optical properties of (V, Pr)-doped $ZrSiO_4$ green pigments, samples were prepared by the ceramic method using NaF and NaCl as mineralizers. They were characterized by X-ray diffraction, UV-Vis spectroscopy and Raman spectroscopy. The changes of color in the samples during heating and effect of mineralizers were studied in terms of valence of the vanadium and praseodymium in the zircon matrix. (V, Pr)-doped $ZrSiO_4$ pigments give rise to green coloration in $800^{\circ}C$. The oxidation state of V and Pr ions of pigments in the glazed samples were confirmed by UV-Vis absorption spectra. This absorption spectra showed three typical bands of trivalent Pr at the 445, 480~490, 592 nm due to f-f transitions and two broad bands of 302~380, 400~500 nm due to f-d transitions of tetravalent Pr. According to the increasing amounts of $Pr_6O_{11}$, the two broad bands showed decreasing intensity at 290, 640 nm due to d-d transitions of tetravalent V.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.333-336
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• 2001

The transient response in PDFA(Praseodymium-Doped Fiber Amplifier) is theoretically investigated. The PDFA has the spectral gain band in 1.3${\mu}{\textrm}{m}$. The transient model includes the transient buildup of the population inversion, the pump power, and the signal power and their transient variation along the fiber amplifier. The numerical analysis of transient model can predict the gain saturation, the variation of pump power and the gain as a function of the fiber length. It also shows the gain saturation and recovery effects depending on the pumping rate lead to distortion and saturation in the amplification of optical pulse. The results of numerical analysis, for the case of the Pr ion concentration of 1000ppm and the pump power of 0.5W the gain saturation is obtained 30dB at the length of 5m and the saturation time of upper level is 250 $mutextrm{s}$.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.15-18
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• 2022

The ultraviolet-C emitting praseodymium doped yttrium phosphate (YPO₄:Pr³⁺) powder was synthesized by conventional solid-state reaction. The electroluminescence device was fabricated by simple screen-printing method using the synthesized YPO₄:Pr³⁺ powder, especially, polyvinylidene fluoride as an insulating layer was applied on the printed YPO₄:Pr³⁺ powder for stable performance of the electroluminescence. The electroluminescence properties were investigated under alternating current power system of 400 Hz. The device starts to emit at 350 V, which showed the ultraviolet-C emission peaking at the 233, 245, 264, 273 nm attributed to electronic transition of the Pr³⁺ ions. The electroluminescence intensity was increased as increasing the operating voltage and the device revealed stable performance up to 600 V due to the polyvinylidene fluoride serve as a protective layer.