• 폴리머
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• 제37권6호
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• pp.736-743
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• 2013

공액구조 고분자의 밴드갭을 줄이기 위하여 청색의 디페닐렌비닐렌을 치환기를 갖는 카바졸 단량체와 용해도 향상을 위해 옥틸기를 도입한 카바졸 공단량체를 합성하여 신규 공중합체를 제조하였다. Suzuki 커플링 중합으로 공중합체를 제조하고, 공중합체의 열적, 분광학적, 전기광학적 특성을 조사하여 고분자 유기발광 다이오드(PLED)의 발광층에의 사용가능성을 조사하였다. 용액상태에서 공중합체의 UV 최대 흡수 파장은 333~340 nm, PL 최대방출 파장은 409~464 nm를 보였으며, 상대양자효율은 최대 25.8%의 값을 보였다. 열중량분석 결과 $350^{\circ}C$까지 열안정성을 보이고, 필름형성이 용이하였으며, 공중합체를 발광층으로 사용한 PLED 소자에서 4.0 V에서 청색광을 나타내었다.

• Journal of Korean Vacuum Science & Technology
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• 제4권3호
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• pp.78-80
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• 2000

We reprot on the fabrication and characterization of InGaN/GaN multiple quantum well light-emitting diode (LED) with a highly transparent Pt ohmic contact as a current spreading layer. The value of light transmittance of a Pt thin film with a thickness of 8 nm on-GaN was measured to be 85% at 450 nm. The peak wavelength and the full-width at half-maximum (FWHM) of the emission spectrum of the LED at 20 mA were 453 nm and 23 nm, respectively. Pt-contacted LEDs show good electrical properties and high light-output efficiency compared to Ni/Au-contacted ones. These results suggest that a Pt thin film can be used as an effective current spreading layer with high light-transparency.

• 한국재료학회지
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• 제18권2호
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• pp.92-97
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• 2008

In spray pyrolysis, the effects of the preparation temperature, flow rate of the carrier gas and concentration of the spray solution on characteristics such as the morphology, size, and emission intensity of $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders under long-wavelength ultraviolet light were investigated. The phosphor powders obtained post-treatment had a range of micron sizes with regular morphologies. However, the composition, crystal structure and photoluminescence intensity of the phosphor powders were affected by the preparation conditions of the precursor powders. The $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders prepared at temperatures that were lower and higher than $700^{\circ}C$ had low photoluminescence intensities due to deficiencies related to the of Cl component. The phosphor powders with the deficient Cl component had impurity peaks of $Ca_2SiO_4$. The optimum flow rates of the carrier gas in the preparation of the $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders with high photoluminescence intensities and regular morphologies were between 40 and 60 l/minute. Phosphor powders prepared from a spray solution above 0.5 M had regular morphologies and high photoluminescence intensities.

• 한국염색가공학회지
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• 제11권3호
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• pp.15-22
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• 1999

This study investigated the mordanting effect of natural mordants such as camellia ash, bean chaff ash and pyrolignite of iron(Iron(II) Acetate) on silk fabrics dyed with green tea extracts. Experimental variables include the conditions of extraction and dyeing, and types of natural mordants. Inorganic ion contents In natural mordants were analysed by Induced Coupled Plasma Atomic Emission Spectrometer. In the ash Al, Fe, Si and Mn were in % unit, Cr and Ni were detected in ppm unit, and in the aqueous extracts of the ash all the metal ions were in ppm unit. On the other hand, fairly high content of Al(2.13% ) in camellia ash extract and Fe(7.91% ) in the aqueous extracts of pyrolignite iron were detected. The absorbance intensity of green tea extracts in UV-Visible spectrum increased with the temperature and time of extraction. The maximum absorption wavelength of the extracts appeared at 272.5nm and 210.5nm. The US values of silk fabrics dyed with green tea extracts were increased with temperature and time of dyeing. Surface color of silk fabric dyed with green tea extracts was 9.1YR, but it was changed from 7.9YR to 7.5YR by camellia ash extract and 7.4YR to 6.4YR by bean chaff ash extract with increase in mordant concentration. Pre-mordanted and post-mordanted fabrics with pyrolignite of iron were changed from 1.4YR to 1.1R and 7.2P to 4.2P, respectively.

• 한국표면공학회지
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• 제48권5호
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• pp.211-217
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• 2015

To fabricate white LED having a high color rendering index value, red color phosphor mixed with the green color phosphor together in the blue chip, namely the blue chips with RG phosphors packaging is most favorable for high power white LEDs. In our previous papers, we reported on successful syntheses of $Sr_{2-}$ $Si_5N_8:Eu^{2+}$ and $CaAlSiN_3$ phosphors for red phosphor. In this work, for high power green phosphor, greenemitting ternary nitride $Ba_3Si_6O_{12}N_2:Eu^{2+}$ phosphor was synthesized in a high frequency induction furnace under $N_2$ gas atmosphere at temperatures up to $1400^{\circ}C$ using $EuF_3$ as a raw material for $Eu^{2+}$ dopant. The effects of molar ratio of component and experimental conditions on luminescence property of prepared phosphors have been investigated. The structure and luminescence properties of prepared $Ba_3Si_6O_{12}N_2:Eu^{2+}$ phosphors were investigated by XRD and photoluminescence spectroscopy. The excitation spectra of $Ba_3Si_6O_{12}N_2:Eu^{2+}$ phosphors indicated broad excitation wavelength range of 250 - 500 nm, namely from UV to blue region with distinct enhanced emission spectrum peaking at ${\approx}530nm$.

• 마이크로전자및패키징학회지
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• 제26권3호
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• pp.71-74
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• 2019

본 연구는 발광층으로의 전자 주입을 억제하기 위해 ZnO 나노입자보다 낮은 전자 이동도를 갖는 $TiO_2$ 나노입자를 무기 전자 수송층으로 사용하여 standard와 inverted 두 가지 구조의 양자점 전계발광 소자를 제작하고 그 특성을 비교하였다. Standard 구조의 소자에서는 전류 밀도가 낮은 것에 비해 inverted 구조의 소자에서는 전류 밀도가 매우 높은 것을 확인하였다. 휘도의 경우 inverted 구조의 소자가 standard 구조의 소자보다 더 높았지만 높은 전류 밀도로 인해 낮은 전류 효율을 나타냈다. 또한 전류 밀도가 높은 만큼 구동 전압이 높았으며, 방출 파장 스펙트럼에서 적색 편이를 확인하였다. Standard 구조의 소자에서 나타난 낮은 전류 밀도를 통해, $TiO_2$ 나노입자가 양자점 전계발광 소자에서 전자 주입을 억제할 수 있는 가능성을 확인하였다.

• Journal of the Optical Society of Korea
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• 제15권1호
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• pp.61-67
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• 2011

The confocal laser scanning microscopy and two-photon microscopy was implemented based on a single laser source and an objective lens. We imaged and compared the morphology of identical sites of ex vivo human skin using both microscopes. The back-scattering emission from the sample provided the contrast for the confocal microscopy. The intrinsic autofluorescence and the second harmonic generation were used as the luminescence source for the two-photon microscopy. The wavelength of the Ti:Sapphire laser was tuned at 710 nm, which corresponds to the excitation peak of NADH and FAD in skin tissue. The various cell layers in the epidermis and the papillary dermis were clearly distinguished by both imaging modalities. The two-photon microscopy more clearly visualized the intercellular region and the nucleus of the cell compared to the confocal microscopy. The fibrous structures in the dermis were more clearly resolved by the confocal microscopy. Numerous cells in papillary dermal layer, as deep as $100\;{\mu}m$, were observed in both CLSM and two-photon microscopy. While most previous studies focused on fibrous structure imaging (collagen and elastin fiber) in the dermis, we demonstrated that the combined imaging with the CLSM and two-photon microscopy can be applied for the non-invasive study of the population, distribution and metabolism of papillary dermal cells in skin.

• 한국결정성장학회지
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• 제29권4호
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• pp.143-148
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• 2019

우리는 분자선 에피택시(Molecular Beam Epitaxy) 법을 사용하여 광전기화학적 물분해 수소생산용 고종횡비 GaN 기반 나노와이어를 Si 기판 위에 성공적으로 제작하였다. 주사전자현미경(SEM)과 에너지분산형 분광법(EDX)은 p-GaN:Mg 및 p-InGaN 나노와이어가 고밀도와 함께 수직으로 성장 되었음을 증명하였다. 또한, p-InGaN 나노와이어의 발광 파장을 552 nm에서 590 nm까지의 조절이 가능하다는 것을 확인하였다. 이렇게 제작된 p-InGaN 나노와이어는 태양광을 통해 외부 전위 없이 물분해가 가능한 수소생산용 광촉매로써 매우 유용하게 사용될 수 있다.

• 한국정보통신학회논문지
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• 제23권3호
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• pp.261-266
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• 2019

유동 세포 분석법은 세포나 입자에 대하여 정밀하고 다양한 광학적 특성을 제공해주는 전기적 탐지 기술이다. 형광 처리된 세포나 미립자에 특정한 파장의 빛을 가함으로써 발생 되는 광 산란과 형광 방출을 통해 세포의 크기와 입상도를 포함한 다차원적인 정보를 제공해주는 유동 세포 분석법은 생체 의학 분야 또는 생물 물리학 분야에서 중요한 역할을 수행한다. 그러나 유동 세포 분석법은 고가이며 장비 설치에 있어 적절한 공간이 필요하고 형광 염료 선택에 제한적이라는 단점을 가지고 있다. 따라서 본 논문에서는, 상용화된 유동 세포 분석에 사용되는 고가의 레이저와 운영시스템 대신 발광 다이오드, 마이크로 컨트롤러와 광 검출기를 사용한 저가의 형광세포 측정 시스템을 개발하여 사용자가 원하는 형광 염료에 대한 자유도를 높였다. 또한, 3D 프린터를 사용하여 모듈별 소형화 및 경량화를 통한 사용자 맞춤형 제작이 가능하도록 하였다. 그 결과, 형광처리 한 세포의 양에 변화를 주어 발광도를 측정하였을 때, 높은 선형성이 보임을 확인할 수 있었다.

• 열처리공학회지
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• 제32권2호
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• pp.74-78
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• 2019

$Zn_2SnO_4$ thin films were deposited on quartzs substrates by using radio-frequency magnetron sputtering system. Thermal treatments at various temperatures were performed to evaluate the effect of annealing temperatures on the properties of $Zn_2SnO_4$ thin films. Surface morphologies were examined by using field emission-scanning electron microscopy and showed that sizes of grains were slightly increased and grain boundaries were clear with increasing annealing temperatures. The deposited $Zn_2SnO_4$ thin films on quartzs substrates were amorphous structures and no distinguishable crystallographic changes were observed with variations of annealing temperatures. The optical transmittance was improved with increasing annealing temperatures and was over 90% in the wavelength region between 350 and 1100 nm at the annealing temperature of $600^{\circ}C$. The optical energy bandgaps, which derived from the absorbance of $Zn_2SnO_4$ thin films, were increased from 3.34 eV to 3.43 eV at the annealing temperatures of $450^{\circ}C$ and $600^{\circ}C$, respectively. As the annealing temperature was increased, the electron concentrations were decreased. The electron mobility was decreased and resistivity was increased with increasing annealing temperatures with exception of $450^{\circ}C$. These results indicate that heat treatments at higher annealing temperatures improve the optical and electrical properties of rf-sputtered $Zn_2SnO_4$ thin films.