• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1404-1407
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• 2005

We have fabricated organic light-emitting diodes using poly(N-vinylcarbazole)(PVK) doped with N,N'- diphenyl-N,N'-bis(3-methylphenyl)-[l,l'-biphenyl]- 4,4/-diamine (TPD) as the hole transport layer. TPD molecules act as the trapping sites in PVK and reduce the hole mobility, which can enhance the electronhole balance in the emitting layer, resulting in the enhanced device performance. We have found the optimum ratio of TPD to PVK for the EL efficiency.

• Journal of the Korean Mathematical Society
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• v.49 no.1
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• pp.99-112
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• 2012

This paper attempts to present a numerical method for solving optimal control problems. The method is based upon constructing the n-th degree Jacobi polynomials to approximate the control vector and use differentiation matrix to approximate derivative term in the state system. The system dynamics are then converted into system of algebraic equations and hence the optimal control problem is reduced to constrained optimization problem. Numerical examples illustrate the robustness, accuracy and efficiency of the proposed method.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.621-624
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• 2007

As a new fluoranthene derivative, a synthesis of benzo[k]fluoranthene was suggested, so new blue emitting materials, 7,12-diphenylbenzo[k] fluoranthene [DPBF] and 7,8,10- triphenylfluoranthene [TPF] were synthesized. $EL_{max}$ wavelength of the device using DPBF as an emitting layer was 436 and 454nm in the deepblue region, which are similar values with PL. The device that used DPBF as an emitting layer showed high efficiency of 2.11cd/A and the excellent color coordinate value of (0.161, 0.131) in deep-blue region.

• Bulletin of the Korean Chemical Society
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• v.10 no.6
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• pp.564-567
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• 1989

The use of some mono-substituted phenyl N-phenylcarbamates derivatives as corrosion inhibitors for nickel in 1M perchloric acid was studied by galvanostatic polarization. The inhibition appears to function through general adsorption isotherm. However, galvanostatic polarization data suggest that in the case of all seven inhibitors both anode are polarized under the influence of an external current. Electrocapillary measurements have also revealed that the tendency of the inhibitors tested to adsorb on metallic surface follows the same order of efficiency.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.634-639
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• 2013

We investigated the effects of a cathode underlayer on the electroluminescence (EL) characteristics of organic light-emitting diodes (OLEDs) using various metal acetates (M-acetate, M = Li, Na, K, Cs) as a cathode underlayer. When 1 nm thick M-acetate layers were used as a cathode underlayer, the OLEDs with M-acetate showed better EL performance than the device with the conventional LiF electron injection layer except the device with Cs-acetate. More enhanced current density and improved EL characteristics were obtained when lower work function metal acetate was employed. In addition, the optimum M-acetate layer thickness that gives the best device performance proved to be 0.7 and 2.0 nm for Li-acetate and Cs-acetate, respectively, probably depending on the molecular size of M-acetate. The OLEDs with the M-acetate layers of optimized thickness demonstrated more than 60% enhanced current efficiency compared with that of the device using an LiF layer at the same applied voltage.

• Current Applied Physics
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• v.18 no.12
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• pp.1496-1506
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• 2018

Organic/inorganic ultraviolet photodetector was fabricated using thermal evaporation technique. Organic/inorganic heterojunction based on thermally evaporated copper (II) acetylacetonate thin film of thickness 200 nm deposited on an n-type silicon substrate is introduced. I-V characteristics of the fabricated heterojunction were investigated under UV illumination of intensity $65mW/cm^2$. The diode parameters such as ideality factor, n, barrier height, ${\Phi}_B$, and reverse saturation current, $I_s$, were determined using thermionic emission theory. The series resistance of the fabricated diode was determined using modified Nord's method. The estimated values of series resistance and barrier height of the diode were about $0.33K{\Omega}$ and 0.72 eV, respectively. The fabricated photodetector exhibited a responsivity and specific detectivity about 9 mA/W and $4.6{\times}10^9$ Jones, respectively. The response behavior of the fabricated photodetector was analyzed through ON-OFF switching behavior. The estimated values of rise and fall time of the present architecture under UV illumination were about 199 ms and 154 ms, respectively. Finally, enhancing the photoresponsivity of the fabricated photodetector, post-deposition plasma treatment process was employed. A remarkable modification of the device performance was noticed as a result of plasma treatment. These modifications are representative in a decrease of series resistance and an increase of photoresponsivity and specific detectivity. The process of plasma treatment achieved an increment of external quantum efficiency from 5.53% to 8.34% at -3.5 V under UV illumination.

• Animal Bioscience
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• v.34 no.5
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• pp.844-854
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• 2021

Objective: The potential of extra virgin olive oil (EVOO), betaine (BET), and ginger (GIN), as natural antioxidants, in reducing negative effects of heat stress on physiological responses, antioxidant capacity, semen quality and fertility of bucks under heat stress were investigated. Methods: Forty adult Animal Production Research Institute line rabbit bucks were distributed randomly into four experimental treatments of ten rabbits each. The first treatment was fed the commercial pellet diet (CPD) without supplementation and served as a control. The other three treatments were fed CPD supplemented with EVOO (300 mg), BET (1,000 mg), and GIN (200 mg) per kg diet for 3 consecutive months during the summer season. Results: Supplementation of EVOO, BET, or GIN improved (p<0.05) the sexual desire, progressive motility, vitality, intact acrosome and membrane integrity, sperm cell concentration, sperm outputs and fertility. Seminal plasma total proteins, globulin, total antioxidant capacity, glutathione and glutathione S-transferase, and initial fructose increased (p<0.05), while total lipids, aspartate and alanine aminotransferases and malondialdehyde decreased (p<0.05) compared with the control. In comparing the natural antioxidants treatments, GIN evoked the largest improvement. Conclusion: The inclusion of GIN (200 mg/kg diet) appeared to improve the sexual desire, semen quality and oxidative stress of bucks. This may be a beneficial supplement for the management of rabbit bucks used in natural mating or artificial insemination.

• The korean journal of orthodontics
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• v.52 no.6
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• pp.399-411
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• 2022

Objective: The objective of this randomized clinical trial was to study the skeletal and dental effects of low-level laser therapy (LLLT) along with a miniscrew-assisted expander (Hyrax) after six months of retention. Methods: After sequence generation, concealed allocation, and implementation, 24 female patients were randomly divided (1:1) into two-groups: bone-borne rapid palatal expansion (BBE) without LLLT (n = 12) and BBE with LLLT (n = 12). Eligibility criteria included female patients aged 10-13 years old with bilateral posterior crossbites. Intraoral and extraoral photographs, cone-beam computed tomography images, and digital study models were obtained before expansion and six months after retention. The 7 mm Hyrax appliance was anchored to four palatal mini-screws, which were activated twice daily for 15 days, then locked and kept in place as a retainer. LLLT was performed in the laser group during expansion and retention, according to the guidelines provided. Results: The records of 24 patients were analyzed. According to the post-retention measurements, both groups showed a significant increase in nasal and maxillary widths and total facial height. In the laser group, the Sella-Nasion-Point A and Point A-Nasion-Point B angles and the interpremolar apical distance were significantly increased. Conclusions: Within the limitations of this study, the results suggest that the parameters and protocol of LLLT do not clinically affect the efficiency of BBE in prepubertal and pubertal patients.

• Analytical Science and Technology
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• v.37 no.1
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• pp.47-62
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• 2024

Abu Gurdi area is located in the South-eastern Desert of Egypt which considered as volcanic massive sulfide deposits (VMS). The present work aims at investigating the ore mineralogy of Abu Gurdi region in addition to the effectiveness of the hydrometallurgical route for processing these ores using alkaline leaching for the extraction of Zn, Cu, and Pb in the presence of hydrogen peroxide, has been investigated. The factors affecting the efficiency of the alkaline leaching of the used ore including the reagent composition, reagent concentration, leaching temperature, leaching time, and Solid /Liquid ratio, have been investigated. It was noted that the sulfide mineralization consists mainly of chalcopyrite, sphalerite, pyrite, galena and bornite. Gold is detected as rare, disseminated crystals within the gangue minerals. Under supergene conditions, secondary copper minerals (covellite, malachite, chrysocolla and atacamite) were formed. The maximum dissolution efficiencies of Cu, Zn, and Pb at the optimum leaching conditions i.e., 250 g/L NaCO₃ - NaHCO₃ alkali concentration, for 3 hr., at 250 ℃, and 1/5 Solid/liquid (S/L) ratio, were 99.48 %, 96.70 % and 99.11 %, respectively. An apparent activation energy for Zn, Cu and Pb dissolution were 21.599, 21.779 and 23.761 kJ.mol^-1, respectively, which were between those of a typical diffusion-controlled process and a chemical reaction-controlled process. Hence, the diffusion of the solid product layer contributed more than the chemical reaction to control the rate of the leaching process. High pure Cu(OH)₂, Pb(OH)₂, and ZnCl₂ were obtained from the finally obtained leach liquor at the optimum leaching conditions by precipitation at different pH. Finally, highly pure Au metal was separated from the mineralized massive sulfide via using adsorption method.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.521-527
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• 2011

Korea announced GHG reduction goal, 30% reduction compare with 2020 BAU and reduction target for each industry sector is planning. Transportation sector also trying to make effective technical and political counterplan of allocated GHG reduction target such as material lightening, energy efficiency improvement and Modal shift technology and so on. Modal Shift is shifting low energy efficiency vehicle to high energy efficiency vehicle which is economically meaningful under current market conditions. We can get not only energy efficiency improvement but also GHG reduction effect through modal shift. Modal Shift is effectively applying and studied in logistics field in Europe and Japan and one of the Indian companies has been registered CDM project activity involving modal shift from roadways to railways for finished goods. In this study, the scenarios are developed with detail modal shift ratio and fuel type base on state of road and rail use and GHG emission factor for each fuel type from MLTM. This result can be used as basic information to improve policies and promote increasing use of train which is more environment friendly transportation vehicle.