• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.412-414
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• 2014

In this study, we investigate atomic and electronic structure of graphene with substitutional impurities such as boron or nitrogen atom using density functional theory (DFT) calculations. To investigate the effects of substitutional impurities in graphene, we consider a ($6{\times}6$) supercell of graphene in our calculations. For detailed electronic properties of graphene, we compare the energy band structure of B- or N-doped graphene with that of pristine graphene.

• Journal of the Optical Society of Korea
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• v.11 no.2
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• pp.63-66
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• 2007

A 9.6 dB gain is observed at 1310 nm in a 5.0 cm bismuth-doped silica fiber. A launched pump power of 100 mW was obtained using an 810-nm laser diode. We demonstrated the simultaneous optical amplification at two wavelengths near second telecommunication windows, which is the range of zero-dispersion for silica fibers.

• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.13-13
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• 2008

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.10
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• pp.662-667
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• 2014

B-doped Si nanoparticles were synthesized by using inductive coupled plasma and specially designed double tube reactor, and their microstructures were investigated. 0~10 sccm of $B_2H_6$ gas was injected during the synthesis of Si nanoparticles from $SiH_4$ gas. Highly crystalline Si nanoparticles were synthesized, and their crystallinity did not change with increase of $B_2H_6$ flow rates. From SEM measurement, their particle sizes were approximately 30 nm regardless of $B_2H_6$ flow rates. From SIMS analysis, almost saturation of B in Si nanoparticles was detected only when 1 sccm of $B_2H_6$ was injected. When $B_2H_6$ flow rate exceeded 5 sccm, higher concentration of B than solubility limit was detected even if any secondary phase was not detected in XRD or HR-TEM results. Due to their high electronic conductivity, those heavily B-doped Si nanoparticles can be a potential candidate for an active material in Li-ion battery anode.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.181-185
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• 1998

Gain characteristic of concatenated erbium-doped fiber amplifiers(EDFA) are studied with a recirculating EDFA loop. For a non-flat gain EDFA, the 3 dB gain bandwidth was reduced to 6 nm after the 20th EDFA. However, for an optimized gain flattened EDFA, in a simple configuration, the 5 dB gain bandwidth was found to be 9nm, even after the 100th EDFA, corresponding to 8000km transmission. This results suggest that the simple optimized flat gain amplifier could be a good candidate for ultra-long distance wavelength division multiplexed transmissions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.89-92
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• 1999

NCZF ferrites doped with B-Bi-Zn(35-25-40) glass ceramics were prepared to investigate the magnetic properties. The XRD peaks of all of samples were observed only spinel phase. As the additive increased at sintering temperature 750$^{\circ}C$ and 850$^{\circ}C$ for 3 hours, the density and shrinkage increased until 5.28g/㎤ and 20%, respectively. According to SEM images, the growth of grain progressed rapidly at sintering temperature 850$^{\circ}C$ for 3 hours. Increasing the additive, initial permeability and complex permeability decreased. The complex permeabilities as a function of frequency showed high values at a12, a16, b11 and b16 sarmples.

• Journal of the Korean Ceramic Society
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• v.37 no.2
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• pp.117-121
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• 2000

Er-doped sodiumborosilicate glass films for waveguides amplifier were fabricated by Aerosol Flame Deposition(AFD) method. Al2O3 was added to sodium borosilicate glass films to suppress the formation of crystalline phase and control the refractive index. the formation of crystalline phase was suppressed above Al2O3 of 6 wt%. As the amount of Al2O3 increased from 2 to 12 wt% the refractive index of glass films increased lineary from 1.4595 up to 1.4710. After the core of 77SiO2-15B2O3-8Na2O＋6 wt%Al2O3＋8wt%Er2O3 was coated on the buffer layer of 77SiO2-15B2O3-8Na2O＋6 wt%Al2O3, the core was etched by reactive ion etching. The absorption spectrum of 3 cm waveguide amplifier showed two peaks of 1530 and 1550 nm.

• Journal of the Korean Vacuum Society
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• v.6 no.1
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• pp.50-60
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• 1997

Undoped, cobalt-doped and erbium-doped $ZnAl_2S_4, ;ZnAl_2Se_4, ;CdAl_2S_4, ;and;CdAl_2Se_4$ single crystals were grown by the chemical transport reaction method. The crystal structures, the lattice constants, the optical energy gaps, and the photoluminescence properties of these single crystals were investigated. Also, the optical transition mechanisms by the impurities of cobalt and erbium were identified from these results.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.167-169
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• 2002

Selective, highly stable determination of serotonin was achieved in cyclic voltammetric measurement carried out at electrochemically treated conductive boron-doped diamond electrode. Boron-doped diamond electrodes were prepared on single crystal Si wafers by microwave plasma chemical vapor deposition and $B_2O_3$ was dissolved in acetone/methanol(9:1) mixture solution so that the B/C weight ratio ca. $10^4ppm$. Serotonin is a kind of indoleamines, which secreted from adrenal marrow cells. The serious problem to detection of serotonin is the interference phenomena of electroactive constituent, including AA. In this study, electrochemical treatment of HDD was carried out to discriminate between serotonin and AA responses. Experimental results showed that the peak potential of AA oxidation shift to the positive direction and the oxidation peak of serotonin was unchanged.

• Korean Journal of Materials Research
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• v.8 no.2
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• pp.173-178
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• 1998

$MgB_4O_7$: Tb, Tm, Dy, La, Ho and Nd phosphors have been prepared by sintering around $580^{\circ}C$ for 2 hours followed by flowing Ar gas. Activation energy and kinetic order of main peak of glow curve were studied by two methods peak shape method and initial rise method. By these methods, the estimated activation energies were $0.76\pm0.02eV$(Tb doped), $0.94\pm0.03eV$(Tm doped), $0.72\pm0.02eV$(Dy doped), respectively. The TL phosphors prepared in this work may be utilized to radiation sensor elements becaue of their high sensitivity to low energy X-ray.