• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1132-1137
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• 2002

In this paper, the test results of the combustion for 2 IAFR lean fuel models are described. The need for the low emission combustor has been issued from the concern on the increase of green house and the destruction of ozone layer. To evaluate the flow and combustion performance of newly designed 21AFR lean modules, the hydraulic tests in stereolithographic airflows models, the low pressure combustion tests in three injectors model for weak extinction and ignition and the high pressure combustion tests in single sector for NOx, SAE and efficiency are performed. The low pressure tests reveal that the governing parameters in weak extinction and ignition at atmospheric condition are prefilmer length, swirl flow rotation direction, secondary swirl angle and flow split. As a result of combustion test at high pressure, the efficiency and smoke level are satisfied with performance targets, but EINOx of 17.8 is higher than target value of 13.1 The high pressure tests show that the main parameters influenced on NOx are primary swirl angle, swirl flow rotation direction, heatshield exit angle and liner mixing hole location.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.9
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• pp.571-575
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• 2014

We synthesized new materials of $Zn(HPB)_2$ and Ir-complexes as blue or red emitting material. We fabricated white Organic Light Emitting Diodes (OLED) by using $Zn(HPB)_2$ for the blue emitting layer, Ir-complexes for the red emitting layer and $Alq_3$ for the green emitting layer. We fabricated white OLED by using double emitting layers of $Zn(HPB)_2$:Ir-complexes and $Alq_3$. The doping rate of Ir-complexes was varied, such as 0.2%, 0.4%, 0.6%, and 0.8%, respectively. When the doping rate of $Zn(HPB)_2$:Ir-complexes was 0.6%, white emission was achieved. The Commission Internationale de l'Eclairage (CIE) coordinates of the white emission was (0.322, 0.312).

• Journal of Korean Society of Water and Wastewater
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• v.24 no.6
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• pp.683-690
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• 2010

Renewable and unutilized energy (biogas power generation, wind power, solar, small hydro-power, sewage heat source, etc.) seems to be suitable to install for the sewage treatment facilities. There are 357 sewage treatment plants in 2007. 17 plants among these have been operating for self-supporting energy by using solar power, small hydro-power and biogas in 2008. Newly built sewage treatment plant of 96,000 $m^3$/day for a newtown is expected to get up to energy consumption of 10 GWh/yr. If solar energy, small hydro-power and biogas-equipments were applied to the new treatment plant, self-supporting energy of the new sewage treatment plant will get up to 56.1%. As a results, about 2,379ton $CO_2$/yr $CO_2$ emission reduction can be expected by using renewable energy. These efforts for self-supporting energy will lead sewage treatment plant to new energy recycle center.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.230-237
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• 2012

Engine makers are lately interested in the gas engine development as the alternative for diesel engine in order to cope the rise of oil price and the environmental regulation. So, STX has developed the 1.6MW gas engine which was converted from 22HLX diesel engine. The gas engine developed with precombustion chamber, which has good performance of 21bar BMEP at engine speed 1000rpm and low $NO_X$ emission of 50ppm at 15% oxygen composition, has been developed recently. Especially, it has a good thermal efficiency of 45% and a reduction efficiency of green house gas($CO_2$) emission of 25% than a conventional diesel engine.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.6
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• pp.27-34
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• 2015

There has been a critical issue in optical simulation of phosphors in LEDs due to their light-reabsorption properties. To improve the accuracy of optical modeling for a white LED package, we utilized the spectrum data of the phosphor-dispersed encapsulant film instead of the phosphor powder. By measuring white LED packages with green and red phosphors, the maximum difference between simulation and experimental results of a color temperature, a color rendition index number and a color coordinate corresponds to ${\Delta}T=95K$, ${\Delta}Ra=1.7$ and ${\Delta}xy=0.007$, respectively. Based on those results, the proposed method can well explain the change of emission spectra of white LEDs with more than two phosphors which introduce the complex optical phenomena such as absorption, reabsorption, light emission, reflection and scattering, etc.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.181-185
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• 2006

The flexible 2-inch AMOLED with $176{\times}144$ pixels has been demonstrated using top emission OLED driven by organic thin film transistors (OTFTs). For the development of AMOLED display on plastic substrate, we have developed several integration and unit process technologies. Through the optimization of the process based on plastic substrate, OTFT backplane with 2 transistors and 1 capacitor in a pixel has been fabricated and integrated with top emission OLED. The active addressing by OTFT driving circuit has been achieved and green light with 15 $cd/m^2$ at 15V has been observed.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1338-1342
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• 2005

We have synthesized an $Eu^{2+}$-activated $Sr_3MgSi_2O_8$ blue phosphor and $Ba_2SiO_4$ green phosphor and $Ba^{2+}$ co-doped $Sr_3SiO_5$ red phosphor investigated an attempt to develop white LEDs by combining it with a GaN blue LED $chip(\lambda_{em}=405 nm)$. Three distinct emission bands from the GaN-based LED and the $(Sr_3MgSi_2O_8:Eu\; +\; Ba_2SiO_4:Eu\; +\; Ba^{2+}\; co-doped\; Sr_3SiO_5:Eu)$ phosphor are clearly observed at 460nm, 520 nm and at around 600 nm, respectively. These three emission bands combine to give a spectrum that appears white to the naked eye. Our results show that GaN (405 nm chip)-based $(Sr_3MgSi_2O_8:Eu\; +\; Ba_2SiO_4:Eu\; +\; Ba^{2+}\; co-doped\; Sr_3SiO_5:Eu) exhibits a better luminous efficiency than that of the industrially available product InGaN (460 nm chip)-based YAG:Ce.

• Journal of Hydrogen and New Energy
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• v.23 no.2
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• pp.173-182
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• 2012

Effects of temperature, pressure, and gas residence time on methane combustion characteristics of mass produced oxygen carrier particle (OCN706-1100) were investigated in a pressurized fluidized bed reactor using methane and air as reactants for reduction and oxidation, respectively. The oxygen carrier showed high fuel conversion, high $CO_2$ selectivity, and low CO concentration at reduction condition and very low NO emission at oxidation condition. Moreover OCN706-1100 particle showed good regeneration ability during successive reduction-oxidation cyclic tests up to the 10th cycle. Fuel conversion and $CO_2$ selectivity decreased and CO emission increased as temperature increased. These results can be explained by trend of calculated equilibrium CO concentration. However, $CO_2$ selectivity increased as pressure increased and fuel conversion increased as gas residence time increased.

• Korean Journal of Materials Research
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• v.27 no.10
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• pp.530-533
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• 2017

ZnO micro/nanocrystals with different morphologies were synthesized by thermal evaporation of various zinc source materials in an air atmosphere. Zinc acetate, zinc carbonate and zinc iodide were used as the source materials. No catalysts or substrates were used in the synthesis of the ZnO crystals. The scanning electron microscope(SEM) image showed that the morphology of ZnO crystals was strongly dependent on the source materials, which suggests that source material is one of the key factors in controlling the morphology of the obtained ZnO crystals. Tetrapods, nanogranular shaped crystals, spherical particles and crayon-shaped crystals were obtained using different source materials. The X-ray diffraction(XRD) pattern revealed that the all the ZnO crystals had hexagonal wurtzite crystalline structures. An ultraviolet emission was observed in the cathodoluminescence spectrum of the ZnO crystals prepared via thermal evaporation of Zn powder. However, a strong green emission centered at around 500 nm was observed in the cathodoluminescence spectra of the ZnO crystals prepared using zinc salts as the source materials.

• Korean Journal of Materials Research
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• v.13 no.10
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• pp.668-672
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• 2003

The ZnO nanorods were synthesized using vapor-solid (VS) method on sodalime glass substrate without the presence of metal catalyst. ZnO nanorods were prepared thermal evaporation of Zn powder at $500^{\circ}C$. As-fabricated ZnO nanorods had an average diameter and length of 85 nm and 1.7 $\mu\textrm{m}$. Transmission electron microscopy revealed that the ZnO nanorods were single crystalline with the growth direction perpendicular to the (101) lattice plane. The influences of reaction time on the formation of the ZnO nanorods were investigated. The photoluminescence measurements showed that the ZnO nanorods had a strong ultraviolet emission at around 380 nm and a green emission at around 500 nm.