• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.47-48
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• 2008

본 연구는 제작된 OLED 소자에 UV의 조사시간에 따른 PL intensity 의 감소와 UV power에 따른 PL degradation 변화에 따라 적절한 UV의 조사조건을 찾아 OLEO 소자의 사진이미지를 구현하고자 하였다. 이러한 조건들로부터 얻어진 OLED 소자의 사진이미지 구현을 통하여 그동안 문제점으로만 여겨졌던 UV에 의한 PL degradation 현상이 문제점만이 아닌 다른 하나의 장점으로 발전되어 다른 분야에서 적용될 수 있다고 기대해본다.

• Macromolecular Research
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• v.10 no.2
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• pp.85-90
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• 2002

Poly (ethylene oxide)/polylatide/poly(ethylene oxide) (PEO/PL/PEO) tri-block copolymers, which each block is connected by ester bond, were synthesized by coupling reaction of PL with PEO in the presence of pyridine. PL/PEO/PL tri-block copolymer was synthesized by ring opening polymerization of L-lactide initiated by PEO in the presence of stannous octoate. Degradation behavior of the copolymers was investigated in a pH 7.4 phosphate buffer saline (PBS) at 37$\pm$1 $^{\circ}C$. Gel permeation chromatography (GPC) and $^1$H-nuclear magnetic resonance (NMR) were used to monitor the change of mass loss, molecular weight and composition of copolymers. In hydrolytic degradation, the PEO/PL/PEO tri-block copolymer with high PEO contents affected the increase of its mass loss, and resulted in the decrease of its molecular weight as well as PEO composition. However, when PL/PEO/PL and PEO/PL/PEO tri-block copolymers had similar PEO contents, PEO/PL/PEO decreased faster in molecular weight and PEO composition than PL/PEO/PL.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.859-862
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• 2008

We have realized static image on organic light emitting diodes (OLEDs) using photoluminescence degradation. Ultraviolet (UV) was irradiated to the glass side of device. UV power was 350 Wand the wavelength was 365 nm. The UV irradiation gives rise to the degradation of photoluminescence. Due to the degradation, the current density-voltage curve was shifted to the higher voltage side and the luminescence was also degraded by the current and photoluminescence drop. The negative imaged films were prepared to control the transmittance of UV. The UV light was passed through the film. By this method, the film image was transferred to the device with reversed image and the static image was realized on the OLED.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.356-361
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• 2009

Lipid oxidation and contents of tocopherols and phospholipids (PL) in soy-added fried products during storage in the dark were studied. Flour dough containing soy flour at 0, 10, 20, and 30% on a weight basis was fried in corn oil at $180^{\circ}C$ for 2.5 min. The fried products were stored at $60^{\circ}C$ for 11 days in the dark. Lipid oxidation of the fried products was evaluated by conjugated dienoic acid (CDA) and p-anisidine values (PAV). Tocopherols and PL were determined by high performance liquid chromatography (HPLC). CDA contents and PAV of the fried products were increased during storage, and addition of soy flour improved lipid oxidative stability of the fried products, which was partly related to increased amount of tocopherols and PL in the soy-added fried products. Tocopherols and PL were degraded during the dark storage of the fried products. Soy flour addition to the dough did not affect the rate of tocopherols degradation during storage of the fried products; however, PL degradation was higher in the soy-added fried products. Residual amounts of $\alpha$-tocopherol and phosphatidylinositol showed high correlations with the lipid oxidation of the fried products during storage in the dark.

• Korean Journal of Materials Research
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• v.31 no.6
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• pp.325-330
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• 2021

Bi₂MoO₆ (BMO) via the structure-directing role of CO(NH₂)₂ is successfully prepared via a facile solvothermal route. The structure, morphology, and photocatalytic performance of the nanoflake BMO are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectrum analysis (PL), UV-vis spectroscopy (UV-vis) and electrochemical test. SEM images show that the size of nanoflake BMO is about 50 ~ 200 nm. PL and electrochemical analysis show that the nanoflake BMO has a lower recombination rate of photogenerated carriers than particle BMO. The photocatalytic degradation of tetracycline hydrochloride (TC) by nanoflake BMO under visible light is investigated. The results show that the nanoflake BMO-3 has the highest degradation efficiency under visible light, and the degradation efficiency reached 75 % within 120 min, attributed to the unique hierarchical structure, efficient carrier separation and sufficient free radicals to generate active center synergies. The photocatalytic reaction mechanism of TC degradation on the nanoflake BMO is proposed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04b
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• pp.49-52
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• 2002

Degradation characteristics of cathodoluminescence (CL) of ZnS:Ag,Cl phosphor were investigated with measurements of CL and photoluminescence (PL). Phosphoric acid treatment was performed to phosphor particles in order to improve CL degradation of phosphor screen that occurred during panel sealing process, and we will discuss mechanisms of degradation and improvement of luminescence mainly with help of AES (auger electron spectroscopy) analysis.

• Journal of the Korean Vacuum Society
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• v.7 no.1
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• pp.11-16
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• 1998

In this study, we prepared a Na$_2$Se/NH$_4$OH solution to investigate a passivation effect of Se on GaAs surface. X-ray photoelectron spectroscopy and photoluminescence (PL) were used to analyse the surface chemical bonding states and the optical properties of GaAs after Se-treatment and a successive exposure to air, respcetively. It was observed that all of the observed selenium bound with arsenic to form As-Se bond and showed only one oxidation state as -2. PL intensity of Se-passivated surface was larger than that of HCI-cleaned surface, and this means that the effective reduction of surface state density of GaAs was successfully obtained by this treatment. However the existence of partial oxide on the Se-passivated surface was seemed to be a major cause to the degradation of Se passivation effcet. PL intensity of Se-passivated surface also decreased according to air-exposure and converged to that of HCI-cleaned surface.

• Transactions on Electrical and Electronic Materials
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• v.12 no.3
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• pp.89-92
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• 2011

Hydrogenated amorphous carbon (a-C:H) films were deposited by plasma enhanced chemical vapor deposition on silicon substrates. a-C:H thin film was irradiated to a typical He-Cd laser to study its emitting properties. The photoluminescence (PL) intensity during the irradiation achieved a maximum value when 2,000 seconds elapsed. Fourier transform infrared measurement revealed a-C:H thin film suffered transformation from a polymer-like to graphite-like phase during laser irradiation. Thermal annealing was done at various temperatures, ranging from room temperature to $400^{\circ}C$ in the atmosphere, to investigate structural changes in a-C:H film by heat generation during the emission. PL intensity of a-C:H thin film increased 1.5 times without apparent structural change, as annealing temperature increased up to $200^{\circ}C$. However, a-C:H film above $200^{\circ}C$ exhibited significant decrease of PL accompanying dehydrogenation. This led to a red shift of the PL peak.

• Macromolecular Research
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• v.12 no.6
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• pp.545-552
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• 2004

The long-term stability of sulfonic acid-containing polyimides has been investigated. The hydrolytic degradation of homopolyimide and the block copolyimide comprising $27\;mol\%$ of 2,2'-bis(trifluoromethyl)benzidine and $9\;mol\%$ of m-phenylenediamine (BTFMB27mPl0[7/(3+1)]), was quantified through viscosity measurements and FT-IR spectroscopic analyses. The viscosity decrease with respect to time and the degradation rate were similar. The degrees of degradation with respect to time under ambient conditions and at elevated temperature in water were monitored by FT-IR spectroscopy. A new absorption peak was observed at $1786\;cm^{-1},$ which we corresponds to the presence of anhydride end groups formed by hydrolytic scission of the imide rings.

• Korean Journal of Materials Research
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• v.31 no.6
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• pp.353-366
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• 2021

In this study, photocatalytic degradation of ammonia in petrochemical wastewater is investigated by solar light photocatalysis. Two-dimensional ultra-thin atomic layer structured MoS₂ are synthesized via a simple hydrothermal method. We examine all prepared samples by means of physical techniques, such as SEM-EDX, HRTEM, FT-IR, BET, XRD, XPS, DRS and PL. And, we use fullerene modified MoS₂ nanosheets to enhance the activity of photochemically generated oxygen (PGO) species. Surface area and pore volumes of the MoS₂-fullerene samples significantly increase due to the existence of MoS₂. And, PGO oxidation of MB, TBA and TMST, causing its concentration in aqueous solution to decrease, is confirmed by the results of PL. The generation of reactive oxygen species is detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It is found that the photocurrent density and the PGO effect increase in the case with modified fullerene. The experimental results show that this heterogeneous catalyst has a degradation of 88.43% achieved through visible light irradiation. The product for the degradation of NH₃ is identified as N₂, but not NO^2- or NO^3-.