• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.12
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• pp.983-987
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• 2010

In order to investigate the emission characteristics of the phosphorescent white organic light-emitting diodes (PHWOLEDs) according to various hole transport layers (HTLs), PHWOLEDs composed of HTLs whose structure are NPB/TCTA, NPB/mCP and NPB/TCTA/mCP, two emissive layers (EMLs) which emit two-wavelengths of light (blue and red), and electron transport layer were fabricated. The applied voltage, power efficiency, and external quantum efficiency at a current density of $1 mA/cm^2$ for the fabricated PHWOLEDs were 7.5 V, 11.5 lm/W, and 15%, in case of NPB/mCP, 5 V, 14.8 lm/W, and 13.7%, in case of NPB/TCTA, and 5.5 V, 14.6 lm/W, and 15%, in case of NPB/TCTA/mCP in the hole transport layer, respectively. High emission efficiency can be obtained when the amount of hole injection from anode is balanced out by the amount of electron injection from the cathode to EML by using NPB/TCTA/mCP structured HTL.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.302-310
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• 2012

Bio assay of mercury and cadmium ions were searched using voltammetric analysis using DNA doped carbon nanotube paste electrodes (DCP). The square-wave stripping voltammetryic optimized results indicated working ranges of 1-10.0 $ngL^{-1}$ and 20-100 $ugL^{-1}$, Hg(II) Cd(II) within an accumulation time of 120 seconds, in 0.1-M phosphate buffer solutions of pH 6.3. The relative standard deviations of 5 $ngL^{-1}$ Hg(II) and Cd(II) that observed were 0.14 and 0.22% (n=12), respectively, using optimum conditions. The low detection limit (S/N) was pegged at 0.1 $ngL^{-1}$ ($4.9{\times}10^{-11}M$) Hg(II) and 0.2 $ngL^{-1}$ ($1.77{\times}10^{-10}M$) Cd(II). The developed methods can be applied to assays in biological fish kidneys and water samples.

• Journal of the Optical Society of Korea
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• v.19 no.1
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• pp.102-111
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• 2015

This paper proposes an algorithm for recovering the colors of objects from multiple near-infrared (near-IR) images. The International Commission on Illumination (CIE) color coordinates of objects are recovered from a series of gray images captured under multiple spectral near-IR illuminations using polynomial regression. The feasibility of the proposed algorithm is tested experimentally by using 24 color patches of the Color Rendition Chart. The experimental apparatus is composed of a monochrome digital camera without an IR cut-off filter and a custom-designed LED illuminator emitting multiple spectral near-IR illuminations, with peak wavelengths near the red edge of the visible band, namely at 700, 740, 780, and 860 nm. The average color difference between the original and the recovered colors for all 24 patches was found to be 11.1. However, if some particular patches with high value are disregarded, the average color difference is reduced to 4.2, and this value is within the acceptability tolerance for complex image on the display.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.4
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• pp.297-304
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• 2017

The purpose of this paper is to analyze losses because of switching devices and the secondary side circuit diodes of 500 W full bridge dc-dc converter by applying gallium nitride (GaN) field-effect transistor (FET), which is one of the wide band gap devices. For the detailed device analysis, we translate the specific resistance relation caused by the GaN FET material property into algebraic expression, and investigate the influence of the GaN FET structure and characteristic on efficiency and system specifications. In addition, we mathematically compare the diode rectifier circuit loss, which is a full bridge dc-dc converter secondary side circuit, with the synchronous rectifier circuit loss using silicon metal-oxide semiconductor (Si MOSFET) or GaN FET, which produce the full bridge dc-dc converter analytical value validity to derive the final efficiency and loss. We also design the heat sink based on the mathematically derived loss value, and suggest the heat sink size by purpose and the heat divergence degree through simulation.

• Journal of the Korean institute of surface engineering
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• v.46 no.2
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• pp.93-97
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• 2013

We studied the emission characteristics of white phosphorescent organic light-emitting diodes (PHOLEDs), which were fabricated using a two-wavelength method. To optimize emission characteristics of white PHOLEDs, white PHOLEDs with co-doping and blue/co-doping emitting layer (EML) structures were fabricated using a host-dopant system. The total thickness of light-emitting layer was 25 nm and the dopant of blue and red was FIrpic and $Bt_2Ir(acac)$ in UGH3, respectively. In case of co-doping structure, applying micro lens array film showed efficiency improvement from the current efficiency 78.5 cd/A and power efficiency 40.4 lm/W to the current efficiency 131.1 cd/A and power efficiency 65 lm/W and blue / co-doping structure showed efficiency improvement from the current efficiency 43.8 cd/A and power efficiency 22 lm/W to the current efficiency 69 cd/A and power efficiency 32 lm/W.

• Food Quality and Culture
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• v.2 no.1
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• pp.43-47
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• 2008

This study examined the quality characteristics of Jeungpyun prepared with different additions of nano-filtered (NF) tofu whey concentrates. The initial pH values of the Jeungpyun batters ranged from 5.64 to 5.78, and decreased to 4.77-4.98 after 4 hours of fermentation at $35^{\circ}C$. The volume and specific volume values of the control Jeungpyun were lower than those of Jeungpyun samples prepared with 1%, 2%, and 3% NF powder. The color of the Jeungpyun became increasingly greenish-yellow as the NF powder level increased. Hardness and brittleness decreased with increasing NF powder content, while cohesiveness and springiness were not significantly different. Sensory evaluations revealed that as the level of NF powder increased, takju smell and sourness increased, but no significant differences were observed for sweetness and moistness between the control and NF powder groups. In terms of overall acceptability, the results revealed that Jeungpyun can be prepared with up to 1% NF powder in place of rice powder and be deemed as acceptable as a control Jeungpyun product.

• The Journal of the Korean bone and joint tumor society
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• v.20 no.2
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• pp.104-108
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• 2014

Bizarre parosteal osteochondromatous proliferation (Nora's lesion) is a rare benign tumor and known to be primarily occur in the small tubular bone of the hands and feet. However, it is very unusual to be reported that it occurs in metatarsal bone in Korea. Thus, we report this tumor of metatarsal bone including the literature review because we have experienced this example.

• The Journal of the Korean bone and joint tumor society
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• v.16 no.2
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• pp.91-94
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• 2010

Fibro-osseous pseudotumor is an extremely rare benign lesion which is fast-growing and painful. It is often misdiagnosed as a malignancy, but it is a noninvasive entity and can be cured by simple resection. We report a case of fibro-osseous pseudotumor of the distal phalanx of great toe in 20-year-old female patient who present with painful mass.

• Journal of the Korean institute of surface engineering
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• v.52 no.2
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• pp.72-77
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• 2019

To study the characteristics of AC driven OLED, we fabricated the fluorescent OLEDs and analyzed the electroluminescence characteristics of OLEDs with AC negative voltage. The luminance and the current density of the OLED decreased, and the number and size of the dark spots increased in proportion to the duration time and level of the applied AC negative voltage. The current efficiency of the OLED was improved when high AC negative voltage was applied within a short time. When the AC negative voltage of 10 V was applied for 1 minute, the efficiency was improved by 12.4%. Also, the degradation of luminance and current efficiency due to the duration of light emission was improved in the case of OLED applied for 1 minute with 10 V AC negative voltage. These are expected as a result of the improvement of the leakage current characteristics by eliminating the short-circuit region formed by the defect of the OLED at the AC negative high voltage. As a result, the continuous application of AC negative voltage reduced the luminance and the current density of OLED, but the temporary application of AC negative voltage with the proper time and voltage could improve the efficiency and lifetime of OLED.

• Journal of Rhinology
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• v.25 no.2
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• pp.114-117
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• 2018

Postoperative maxillary cyst (POMC) is relatively common complication among patients who underwent Caldwell-Luc surgery. Patients with POMC usually have no symptoms, although cyst extension can result in bone destruction or cystic infection with pain. The trigeminal nerve consists of the ophthalmic nerve, maxillary nerve, and mandibular nerve. Among these branches, the maxillary nerve runs to the lateral and frontal sides of the maxillary sinus wall. POMC can rarely lead to trigeminal neuropathy caused by cyst enlargement that compresses some branches of the trigeminal nerve. Recently, we experienced a case with trigeminal neuralgia due to POMC. The patient was successfully treated with inferior meatal antrostomy. We report this rare case with a literature review.