• Journal of the Korean Applied Science and Technology
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• v.26 no.3
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• pp.357-361
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• 2009

The authors have demonstrated white oraganic light-emitting diodes (WOLED) using 1,4-bis[2-(4'-diphenylaminobiphenyl-4-yl)vinyl]benzene as fluorescent blue emitter and iridium(III) bis(5-acetyl-2-phenylpyridinato-N,C2') acetylacetonate as phosphorescent red emitter. The optimized WOLED using red host material as bis(2-methyl-8-quinolinato) -4-phenylphenolate exhibited proper color stability in comparison with the control device using 4,4'-N,N'-dicarbazole-biphenyl as red host. The white device showed a maximum luminance of 21100 $cd/m^2$ at 14 V, luminous efficiency of 9.7 cd/A at 20 $mA/cm^2$, and Commission Internationale de I'Eclairage ($CIE_{x,y}$)coordinates of (0.32, 0.34) at 1000 $cd/m^2$. The devices also exhibited the color shift with ${\Delta}CIE_{x,y}$ coordinates of ${\pm}$ (0.01,0.01) from 100 to 20000 $cd/m^2$.

• Transactions on Electrical and Electronic Materials
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• v.10 no.6
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• pp.208-211
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• 2009

The authors have demonstrated the various characteristics of hybrid white organic light-emitting diodes (HWOLED) using fluorescent blue and phosphorescent red emitters. We also demonstrated that two devices showed different characteristics in accordance with thickness of the 4,4′-N,N′-dicarbazole-biphenyl (CBP) spacer (CS) inserted between the blue and the red emitting layer. It was found that the device with a CS thickness of 70 $\AA$ showed a current efficiency 2.5 times higher than that of the control device with a CS thickness of 30 $\AA$ by preventing the triplet Dexter energy transfer from the red to the blue emitting layer. The HWOLED with the CS thickness of 70 $\AA$ exhibited a maximum luminance of 24500 cd/$m^2$, a maximum current efficiency of 42.9 cd/A, a power efficiency of 37.5 lm/W, and Commission Internationale de I'Eclairage coordinates of (0.37, 0.42).

• Transactions on Electrical and Electronic Materials
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• v.8 no.5
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• pp.215-217
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• 2007

Recently, color reproduction properties have attracted lots of attention with mass production of LCD especially corresponding to TV application and achievement of color reproduction properties such as CRT have been considered one of technical goals for high quality display. However, revision of the color reproduction properties only with CF(color filter) have fundamental limitations and resultant decrease in the transmittance of panel causes demand on high brightness of BL(Back Light). In this paper, we present such a method in which by optimization of original light spectrum from the BL source will improves the color reproduction properties corresponding to them of the CRT. When the intensity of RED and Green-Blue from ramp is revised densely, the characteristics different from CCFL(Cold Cathode Fluorescent Lamp) used before become added so that about 11 % of the color reproduction properties is improved compare to the existing LCD panel.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.7
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• pp.641-646
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• 2005

To fabricate a single layer white organic light emitting diode (OLED), a novel non-conjugated blue emitting material PPPMA-co-DTPM copolymer was synthesized containing a perylene moiety unit with hole transporting and blue emitting ability and a triazine moiety unit with electron transporting ability. The devices were fabricated using PPPMA-co-DTPM $(PPPMA[70\;wt\%]:DTPM[30\;wt\%])$ copolymer by varying the doping concentrations of each red, green and blue fluorescent dye, by molecular-dispersing into Toluene solvent with spin coating method. In case of ITO/PPPMA-co-DTPM:TPB$(3\;mol\%):C6(0.04\;mol\%):NR(0.015\;mol\%)/Al$ structure, as they were molecular-dispersing into 30 mg/ml Toluene solvent, nearly-pure white light was obtained both (0.325, 0.339) in the CIE coordinates at 18 V and (0.335, 0.345) at 15 V. The turn-on voltage was 3 V, the light-emitting turn-on voltage was 4 V, and the maximum external quantum efficiency was $0.667\%$ at 24.5 V. Also, in case of using 40 mg/ml Toluene solvent, the CIE coordinate was (0.345, 0.342) at 20 V.

• Journal of the Korean Society of Food Culture
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• v.13 no.5
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• pp.519-528
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• 1998

This study was conducted to investigate the changes in lipid components of red pepper under various processing conditions such as drying, exposing to lights, extraction and storage conditions. The material used in this study were Chungyang cultivars which contained the largest amount of capsaicinoids and Dabok cultivars which is most popular among the various cultivars produced in Korea. Total lipid content of Chungyang was 15.7% and those of Dabok, Udeungsang and Hongilpum were about 17%. The neutral lipid content in free lipid of red pepper was $78.5{\sim}80.3%$ Phospholipid and glycolipid content in bound lipid were $53.8{\sim}56.9%$ and $35.3{\sim}38.7%$ respectively. The major fatty acids of lipid were linoleic, palmitic and oleic acid. Linoleic acid was presented mainly in pericarp, seed and placenta, whereas the most of palmitic acid was presented in stem. Lipid content of cut and whole red pepper were decreased $24.7{\sim}28%$ and $18.1{\sim}21.5%$ by drying for 48hrs at $65^{\circ}C$ and $95^{\circ}C$. And lipid content was also decreased $3.5{\sim}3.6%$ when the red pepper powder was exposed to 15,000 lux of incandescent light for 30 days at $40^{\circ}C$ and $4{\sim}4.9%$ to fluorescent light. The lipid was extracted the highest content of $50.5{\sim}51.7%$ by acid solution(pH2) and the lowest content by neutral solution, and the higher the salt concentration, the greater the lipid was extracted. During storage at $4^{\circ}C,\;25^{\circ}C,\;40^{\circ}C$, for 30 days the lipid content was not much changed but linoleic acid content was decreased during storage at the same conditions.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.34-34
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• 2011

Recently, people have concerned about environmental pollution. This environmental pollution occur due to many reasons such as heavy metal ions and anions. In this regard, many researchers have studied organic materials to monitor above reasons to protect environmental pollution. One of the organic materials for this function is chemosensor. This chemosensor has been studied and reported about monitoring toxic heavy metal ions and anions. In this study, the dye sensor was designed and synthesized through reaction of Rhodamine 6G and 1,3-Indanedion. this dye sensor selective detected $Hg^{2+}$ metal ions while showing red color absorption and yellowish-green strong fluorescence emission compared to other heavy metal ions such as $Cu^{2+}$, $Hg^{2+}$, $Ag^{2+}$, $Zn^{2+}$, $Fe^{2+}$ and $Fe^{3+}$. In this regard, we anticipated that this dye senosr can provide an significant material for monitoring mercury which cause environmental pollution. Thus, We investigated detailed properties of this dye sesnor with using UV-Vis absorption and fluorescent spectrophotometer, Job's plot method for metal binding complex, computational simulated calculation named Material Studio 4.3 suite to approach for electron distribution and HOMO/LUMO.

• Rapid Communication in Photoscience
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• v.2 no.1
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• pp.24-27
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• 2013

A polymeric photobase generator containing oxime-urethane groups is applied to a fluorescence micropatterning material. Polymer bearing oxime-urethane groups was prepared by copolymerization of methyl methacrylate with methacryloyloxyethyl benzophenoneoxime urethane (MBU). The reaction of amino groups in the irradiated copolymer film with dansyl chloride (Dns-Cl) was monitored by using UV absorption, IR absorption and fluorescence spectroscopy. The fluorescence spectrum of the Dns-Cl-treated irradiated copolymer film shows a strong fluorescence with a fluorescence maximum wavelength at 510 nm. A blue fluorescent micropattern with a line width of $2{\sim}3{\mu}m$ was obtained. Treatment of the irradiated copolymer film with Dns-Cl and rhodamine B mixture led to the formation of green, red, and orange-colored fluorescence micropatterns. Thus, various colored micropatterns on a single polymer film can be obtained by selective excitation of each dye molecules.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.165-168
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• 2003

최근 TV 대응 LCD 제품의 본격적인 양산과 더불어 LCD TV 의 색재현성에 대한 해결과제가 큰 문제로 대두되고 있으며, CRT 급 색재현성의 확보는 LCD TV 의 고급화를 위한 또 하나의 개발 방향이 되고 있다. 그러나, CF(Color Filter)만을 이용한 색재현성의 개선은 근본적으로 한계를 가지고 있으며, 패널 투과율의 저하로 이어져 또다시 고휘도 사양의 BL(Back Light)에 대한 요구가 발생하고 있다. 따라서 본 연구에서는 CF(Color Filter)만에 의한 색재현성의 개선이 아닌 BL 광원 자체의 스펙트럼 최적화를 통해서 CRT 급 색재현성의 확보를 통한 고부가가치 상품개발의 가능성을 제시하고자 하였다. 구체적으로, 램프형광체의 RED 와 Green-Blue 영역에서의 Intensity 향상을 통해서 기존의 CCFL(Cold Cathode Fluorescent Lamp)과는 다른 특성을 광원에 부가하여, 기본의 LCD 패널을 그대로 이용한 경우에도 색재현성을 약 11% 개선하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.142-147
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• 2015

The artificial light sources for growth of plant are usually high-pressure sodium lamp, metal haloids lamp, and fluorescent light; however, these light sources have relatively weaker Red and Blue lights that are necessary for growth of plants. Especially the effect of Photosynthetic Photon Flux Density (PPFD) is pointed out as the weakness. Meanwhile, LED light source can be selected by specific wavelength to greatly improve the effect of PPFD. In this regard, this paper aims to investigate the promotion of plant growth by measuring photosynthetic photon flux density (hereafter referred to as PPFD) according to changes in light quality of the LED light sources. Towards this end, LED light sources for plant growth were produced with 4 kinds of mono-chromatic lights and 6 kinds of combined lights by mixing red, blue, green and white lights. A comparative analysis was conducted to investigate the effects of optical properties and PPFD on plants (green leaf lettuce) using the produced light sources. The results monochromatic light has fastest growth rate, but plant growth conditions have poor. This being so, mixed light is suitable for the green leaf lettuce.

• Current Optics and Photonics
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• v.3 no.3
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• pp.256-262
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• 2019

Extensive tumor resection accompanied by radiotherapy and chemotherapy is the standard of care for malignant gliomas. However, there is a significant obstacle to the complete resection of the tumor due to the difficulty of distinguishing tumor and normal brain tissue with a conventional surgical microscope. Recently, multiple studies have shown the possibility of fluorescence-guided surgery in malignant gliomas. The most used fluorescence dyes for brain tumor surgery are 5-aminolevulinic acid (5-ALA) and indocyanine green (ICG). In this paper, a new fluorescence guided operation system, which can detect both 5-ALA and ICG fluorescent images simultaneously, is presented. This operation system consists of light emitting diodes (LEDs) which emits 410 nm and 740 nm wavelengths. We have performed experiments on rats in order to verify the operation of the newly developed operation system. Oral administration and imaging were performed to observe the fluorescence of 5-ALA and ICG fluorescence in rats. When LEDs at wavelengths of 410 nm and 740 nm were irradiated on rats, 628 nm wavelength with a violet fluorescence color and 825 nm wavelength with a red fluorescence color were expressed in 5-ALA and ICG fluorescent material, respectively, thus we were able to distinguish the tumor tissues easily. Previously, due to the poor resolution of the conventional surgical microscope and the fact that the color of the vein is similar to that of the tumor, the tumor resection margin was not easy to observe, thus increasing the likelihood for cancer recurrence. However, when the tumor is observed through the fluorescence guided operation system, it is possible to easily distinguish the color with the naked eye and it can be completely removed. Therefore, it is expected that surgical removal of cancerous tumors will be possible and surgical applications and surgical microscopes for cancer tumor removal surgery will be promising in the future.