• Transactions on Electrical and Electronic Materials
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• v.9 no.1
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• pp.20-23
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• 2008

Organic light-emitting diodes (OLEDs) are attractive because of possible application in display with low-operating voltage, low-power consumption, self-emission and capability of multicolor emission by the selection of emissive materials. To investigated the optical effects, we studied the electrical and optical characteristics due to thickness variation of electron injection materials LiF on organic light-emitting diodes in the ITO (indium-tin-oxide)/N,N'-diphenyl-N, N'-bis(3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris(8-hydroxyquinoline) aluminum $(Alq_3)/LiF$ layer/Al device. We maintained the thicknesses of TPD and $Alq_3$ layers at 40 nm and 60 nm, respectively. The deposition rates of TPD and $Alq_3$ were in the $1.5{\AA}/s$ under a base pressure of $5{\times}10^{-6}$ Torr. It was found that luminance and luminous efficiency of the device with 0.7 nm LiF layer improve 25 times and 7 times than the device without the LiF layer, respectively.

• Journal of Fashion Business
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• v.24 no.2
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• pp.44-59
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• 2020

This investigated the romanticism of Alessandro Michele who leads new trends in fashion industry as a creative director for Gucci. In this study, 307 women's wears exhibited by Alessandro Michele for 3 years in Milan collections from 2015 F/W to 2017 F/W are categorized according to the aesthetic characteristics of romanticism. Additionally, the five aesthetic features of Gucci's fashion design are an addition since the appearance of abnormally large size under the influence of postmodernism. The results based on the study purpose are as follows. First, the decoration makes the garments stand out by using fancy materials, splendid multicolor combination, applique embroidery and three-dimensional objects. Second, exotic style is expressed from an occidental perspective using Chinese traditional fashion or textiles, and exotic accessories. Thirdly, sensuality is manifested using see-through materials to emphasize women's breasts, or the beautiful and sexual expression of women's body. Fourth, the new creations are designed by combining contrasting elements, such as disparate materials and, different genders. Furthermore, traditional cultures like baroque and rococo, and the 1970's vintage looks inspires the creation of retro-style. Finally, the appearance of extremely large shoulders, silhouettes, and details of the human body can be explained with expansive tendency. The aforementioned results further suggest that diverse characteristics are expressed via reflection of contemporary art and trends.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.871-877
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• 1998

Electroluminescent(EL) devices based on organic materials have been of great interest due to their possible applications for large-area flat-panel displays, where they are attractive because of their capability of multicolor emission, and low operation voltage. In this study, glass substrate/ITO/Eu(TTA)$_3$(phen)/Al, glass substrate/ITO/Eu(TTA)$_3$(phen)/Al and glass substrate/ITO/Eu(TTA)$_3$(phen)/AlQ$_3$/Al structures were fabricated by vacuum evaporation method, where aromatic diamine(TPD) was used as a hole transporting material, Eu(TTA)$_3$(phen) as an emitting material, and Tris(8-hydroxyquinoline) aluminu-m(AlQ$_3$) as an electron transporting layer. Electrolumescent(EL) and I-V characteristics of Eu(TTA)$_3$-(-phen) were investigated. These structures show the red EL spectra, which are almost the same at the PL spectrum of Eu(TTA)$_3$(phen). I-V characteristics of this structure show that turn-on voltage was 9V and current density was 0.01A/㎤ at a operation voltage of 9V. Electrical transporting phenomena of these structures were explained using the trapped-charge-limited current model with I-V characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.317-320
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• 1998

Electroluminescent(EL) devices based on organic materials have been of great interest due to their possible applications for large-area flat-panel displays, where they are attractive because of their capability of multicolor emission, and low operation voltage. In this study, glass substrate/ITO/Eu(TTA)$_3$(Phen)/Al(A), glass substrate/ITO/TPD/Eu(TTA)$_3$(phen)/Al(B) aNd glass substrate/ITO/TPD/Eu(TTA)$_3$(Phen)/A1Q$_3$/Al (C) structures were fabricated by vacuum evaporation method, where aromatic diamine(TPD) was used as a hole transporting material, Eu(TTA)$_3$(phen) as an emitting material, and tris(8-hydroxyquinoline) Aluminum (AlQ$_3$) as an electron transporting layer. Etectroluminescent(EL) and I-V characteristics of Eu(TTA)$_3$(phen) with a various thickness were investigated. This structure shows the red EL spectrum, which is almost the same as the PL spectrum of Eu(TTA)$_3$(phen). I-V characteristics of this structure show that turn-on voltage was 9V and current density was 0.01A/㎤ at a dc operation voltage of 9V. Electrical transporting phenomena of these structures was explained using the trapped-charge-limited current model with I-V characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.54-55
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• 2006

Organic light-emitting diodes(OLEOs) are attractive because of possible application in display with low operating voltage, low power consumption, self-emission and capability of multicolor emission by the selection of emissive material. We investigated the effects of deposition rate on the electrical characteristics, physical characteristics and optical characteristics of OLEOs in the ITO(indium-tin-oxide)/N.N'-diphenyl-N,N'-bis(3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris(8-hydroxyquinoline)aluminum($Alq_3$)/Al device. We measured current density, luminous flux and luminance characteristics of devices with varying deposition rates of TPD and $Alq_3$. It has been found that optimal deposition rate of TPD and $Alq_3$ were respectively $1.5{\AA}/s$ from the device structure. An AFM measurement results, surface roughness of the deposited film was the lowest when deposition rate was $1.5{\AA}/s$.

• Smart Structures and Systems
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• v.10 no.1
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• pp.67-87
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• 2012

A dragonfly inspired flapping wing is investigated in this paper. The flapping wing is actuated from the root by a PZT-5H and PZN-7%PT single crystal unimorph in the piezofan configuration. The non-linear governing equations of motion of the smart flapping wing are obtained using the Hamilton's principle. These equations are then discretized using the Galerkin method and solved using the method of multiple scales. Dynamic characteristics of smart flapping wings having the same size as the actual wings of three different dragonfly species Aeshna Multicolor, Anax Parthenope Julius and Sympetrum Frequens are analyzed using numerical simulations. An unsteady aerodynamic model is used to obtain the aerodynamic forces. Finally, a comparative study of performances of three piezoelectrically actuated flapping wings is performed. The numerical results in this paper show that use of PZN-7%PT single crystal piezoceramic can lead to considerable amount of wing weight reduction and increase of lift and thrust force compared to PZT-5H material. It is also shown that dragonfly inspired smart flapping wings actuated by single crystal piezoceramic are a viable contender for insect scale flapping wing micro air vehicles.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.2
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• pp.38-44
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• 2021

To cater to the transition from single-color to multicolor/multi-material printing, this paper proposes a cartridge-replacing type multi-nozzle Fused Depositon Modeling(FDM) three-dimensional (3D) printer. In the test printing run, tool change failure/wobble/layer shift occurred. It was confirmed that improper support was the cause of this tool change failure. As a solution, spline and electromagnetic cartridges were designed. Wobble was caused by machine vibration and the motor stepping out. To minimize wobble, an additional Z-axis was installed, and the four-point bed leveling method was used instead of the three-point bed leveling method. The occurrence of layer shift was ascribed to the eccentricity of the Z-axis lead screw. Therefore, slit coupler was replaced with an Oldham type. In addition to the mechanical supplementation, the control environment was integrated to prevent accidents and signal errors due to wire connections. Before the final test printing run, a rectifier circuit was added to the motor to secure precise control stability. The final test printing run confirmed that the wobble/layer shift phenomenon was minimized, and the maximum error between layers was reduced to 0.05.

• Molecules and Cells
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• v.26 no.2
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• pp.113-120
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• 2008

Laser light microscopy enables observation of various simultaneously occurring events in living cells. This capability is important for monitoring the spatiotemporal patterns of the molecular interactions underlying such events. Two-photon excited fluorescence microscopy (two-photon microscopy), a technology based on multiphoton excitation, is one of the most promising candidates for such imaging. The advantages of two-photon microscopy have spurred wider adoption of the method, especially in neurological studies. Multicolor excitation capability, one advantage of two-photon microscopy, has enabled the quantification of spatiotemporal patterns of $[Ca^{2+}]_i$ and single episodes of fusion pore openings during exocytosis. In pancreatic acinar cells, we have successfully demonstrated the existence of "sequential compound exocytosis" for the first time, a process which has subsequently been identified in a wide variety of secretory cells including exocrine, endocrine and blood cells. Our newly developed method, the two-photon extracellular polar-tracer imaging-based quantification (TEPIQ) method, can be used for determining fusion pores and the diameters of vesicles smaller than the diffraction-limited resolution. Furthermore, two-photon microscopy has the demonstrated capability of obtaining cross-sectional images from deep layers within nearly intact tissue samples over long observation times with excellent spatial resolution. Recently, we have successfully observed a neuron located deeper than 0.9 mm from the brain cortex surface in an anesthetized mouse. This microscopy also enables the monitoring of long-term changes in neural or glial cells in a living mouse. This minireview describes both the current and anticipated capabilities of two-photon microscopy, based on a discussion of previous publications and recently obtained data.

• Journal of the Korean institute of surface engineering
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• v.50 no.3
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• pp.206-211
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• 2017

$BiNbO_4:RE^{3+}$ (RE = Dy, Eu, Sm, Tb) phosphors were prepared by solid-state reaction at $1100^{\circ}C$ and their structural, photoluminescent, and morphological properties were investigated. XRD patterns exhibited that all the synthesized phosphors exhibited a triclinic system with a dominant (210) diffraction peak, irrespective of the type of activator ions. The surface morphologies of rare-earth-ion-doped $BiNbO_4$ phosphors were found to depend strongly on the type of activator ions. The $Eu^{3+}$ and $Dy^{3+}$ doped $BiNbO_4$ phosphors revealed a strong red (613 nm) emission resulting from the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ and a dominant yellow (575 nm) emission originating from the $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transition of $Dy^{3+}$ respectively, which were the electric dipole transitions, indicating that the activator ions occupy sites of non-inversion symmetry in the $BiNbO_4$ phosphor. The main reddish-orange emission spectra of $Sm^{3+}$-doped $BiNbO_4$ phosphors were due to the $^4G_{5/2}{\rightarrow}^6H_{7/2}$ (607 nm) magnetic dipole transition, indicating that the $Sm^{3+}$ ions were located at inversion symmetry sites in the $BiNbO_4$ host lattice. As for $Tb^{3+}$-doped phosphors, green emission was obtained under excitation at 353 nm and its CIE chromaticity coordinates were (0.274, 0.376). These results suggest that multicolor emission can be achieved by changing the type of activator ions incorporated into the $BiNbO_4$ host crystal.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.7
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• pp.2771-2775
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• 2015

Background: Associations between ABO blood groups and risk of several malignancies have been reported, although there are limited data regarding hepatocellular carcinoma (HCC). The aim of this study was to investigate any possible association between the ABO genotype, especially blood group A, and HCC risk in Koreans. Materials and Methods: We conducted a case-control study of 1,538 patients with newly diagnosed HCC at Chonnam National University Hwasun Hospital and 1,305 randomly selected members of the general population. The ABO genotype was determined by multicolor real-time polymerase chain reaction (PCR) using displacing probes. Adjusted odds ratios (aORs) and their 95% confidence intervals (CIs) were calculated using logistic regression models with adjustment for gender, age, smoking, alcohol drinking, and hepatitis B and C status. Results: The risk of HCC in genotype AA was significantly higher than in OO (aOR=1.773, 95% CI=1.161-2.705). The risk in blood group A was also higher than in blood group O (aOR=1.448, 95% CI=1.005 1.897). No significant difference was found for the AA, BO, BB, and AB genotypes, or blood group B and AB. Conclusions: Blood group A and genotype AA showed the highest risks of HCC in a Korean population. No significant difference was found for the AO, BO, BB, and AB genotypes, or blood group B and AB.