• Composites Research
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• v.24 no.4
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• pp.5-10
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• 2011

As environmental pollution getting worse, biodegradable materials have been drawn more attention than ever. In this study, polylactic acid (PLA)/carbon nanotubc (CNT) nanocomposites were manufactured via extrusion molding and injection molding, In order to change the crystallinity, annealing treatment was done for different time span, Crystallization kinetics of PLA was analyzed by differential scanning calorimeter (DSC), and it was confirmed that a proper amount of CNT can increase the crystallization rate of PLA. In addition, the presence of CNT significantly accelerates the hydrolytic degradation rate of PLA, however, it decreases with the increase of crystallinity. The reason is that degradation may occur in the PLA/CNT interface easily, and the molecular structure of the composite becomes dense with the increase of crystallinity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4334-4340
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• 2012

In this work, we developed and evaluated the Liquid Particle Generator for generating fine particles in the air. The Liquid Particle Generator, which was based on the spray-evaporation method, had two kinds of orifices: 0.3 mm and 0.5 mm. The Liquid Particle Generator was operated at different pressure between 1 bar and 4 bars to find relationship between input pressure and droplet output rate. In addition, the size distribution of the droplets generated by the Liquid Particle Generator with different orifices was measured by the SMPS system and the optical particle counter. As a result, it was shown that the Liquid Particle Generator with 0.3 mm orifice generated droplets of around 0.3 ${\mu}m$ and atomized particles very stably. The Liquid Particle Generator having 0.5 mm orifice generated bigger droplets, compared with the Liquid Particle Generator with 0.3 mm orifice. Additionally, in these Liquid Particle Generators (0.3 mm and 0.5 mm orifice), little coagulation of particles did occur because of fine droplets atomized by the jet. Therefore, the Liquid Particle Generator could be used as an aerosol generator for atomizing fine particles.

• Journal of Bio-Environment Control
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• v.9 no.4
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• pp.223-229
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• 2000

This study was conducted to analyze the opto-electric characteristics of light-emitting diodes(LED) designed for growth and morphogenesis control of transplant and to quantify the photon flux emittig from LED using a quantum sensor spectroradiometer. Difference in photon flux for blue and red LED between measured by a quantum sensor and measured by a spectroradiometer and numerically integrated was not observed. This result implies a spectroradiometer can be applied to quantify the photon flux emitting from far-red LED, which can not be measured using a quantum sensor. Since photon flux increases in proportion to wavelength, photon flux of LED modules arranged for red and far-red increased in proportion to wavelength, photon flux of LED modules arranged for red and rar-red increased gradually as the number of LED stick emitting far-red in LEd modules increased. Illumination of LED modules arranged for red and far-red decreased as the number of LED stick emitting far-red in LED modules increased. There was no difference in irradiance between LED modules arranged for red and far-red.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1789-1797
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• 2000

The objective of this study was to assess parameters affecting nitrite accumulation, which offers advantages in terms of less aeration energy and carbon consumption for denitrification. The influence of the alkalinity to $NH_4{^+}-N$ concentration ratio, pH, FA(free ammonia) concentration and temperature on nitrite accumulation was investigated. The experiment was performed with supernatant from dewatering process of anaerobic digested sludge using a submerged biofilm reactor. The influent contains high strength of ammonium nitrogen and the alkalinity was insufficient for complete nitrification. An increased nitrite accumulation was observed with increase in alkalinity to $NH_4{^+}-N$ concentration ratio. The increase in alkalinity to $NH_4{^+}-N$ concentration ratio has been a maior reason for the high pH value and FA concentration in the reactor. It can be considered that selective inhibition of Nitrobacter can be causes of nitrite accumulation. The nitrite accumulation increased with increment of temperature at fixed alkalinity to $NH_4{^+}-N$ concentration ratio.

• Membrane Journal
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• v.23 no.3
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• pp.251-256
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• 2013

In this study, acetylated methyl cellulose (AMC) was successfully used as a support layer of thin film composite (TFC) forward osmosis (FO) membrane. A selective polyamide active layer, interfacially polymerized, was coated on top of various substrate layers. The structure and performance of the TFC FO membrane based on the AMC substrate were compared with those of TFC FO membranes with different polymeric support layers. The experimental results showed that the AMC FO membrane performance was better than other FO membranes due to its characteristic morphology and lower back diffusion rate of salts.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.633-638
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• 2008

The bunsen reaction, part of IS(Iodine-sulfur) cycle that one of the hydrogen production by the thermochemical water splitting, was investigated. It was observed that $H_2SO_4$ was uniformly generated and generation of $H_2SO_4$ was independent of iodine input. However, generation of HI was decreased with increasing iodine input. It was thought that HI and unreacted iodine were formed complex compound such as $HI_3$ $HI_5$ or $HI_7$. The complex compound accelerated liquid-liquid separation properties in the product. It was also revealed that reaction kinetics was increased with increasing iodine input. Liquid-liquid separation properties were improved with increasing iodine input and reaction temperature. Moreover, no side reaction was occurred at all reaction conditions.

• Journal of the Korean Ceramic Society
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• v.40 no.12
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• pp.1224-1228
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• 2003

The crystallization behavior of a luster glaze containing ceria has been investigated. When glazed specimens were sintered at 110$0^{\circ}C$, crystalline ceria particles were preferentially precipitated with (100) planes parallel to the specimen surface with the size of around 200 nm. The particle population in the surface region was much higher than inside glaze, covering over 60% of the specimen surface area. Crystallization of the particles with preferred orientation was promoted, after the removal of internal interface through complete melting of the fit particles. The luster effect seems to result from CeO$_2$ particles of high refractive index, their strong light scattering at visible rage due to fine crystalline size 200 nm and their planar arrangement in the surface region.

• Analytical Science and Technology
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• v.25 no.4
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• pp.242-249
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• 2012

Total 11 samples of sediments from the Geum river and the Nakdong river and its estuaries were analyzed to investigate the distribution characteristics of PBDEs and HBCD. Concentration of PBDEs in sediments ranged from 2.19~101.34 (average 30.70, median 20.91) ng/g-dw. The concentration range of PBDEs in river sediments is greater than those of estuary sediments. The HBCD concentration was ranged from N.D.~7.85 (average 1.47, median 0.32) ng/g-dw. HBCD concentrations compared with PBDEs are approximately 1/20 level, which is associated with low domestic usage. Isomer patterns of PBDEs and HBCD suggested that not only the use of commercial products, but the physicochemical properties of these materials, environmental degradation, and environmental behavior could affect the distribution characteristics of these chemicals and their isomers.

• Korean Journal of Construction Engineering and Management
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• v.16 no.2
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• pp.3-11
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• 2015

The urban has been improved houses and facilities as accelerating industry and society, while the rural area was inferior to the city. Furthermore, there was not a maintenance in time as ageing, and did not expect to rebuilding of using proper techniques and materials for financial reasons. This study find a way to make a revitalizing plan for appropriate real state. For this, perform a current status survey that 900 rural residences of 36 rural villages in Chungcheong area. As a result, Korean traditional structure is a half in residential type, and has poor residential conditions by comparison with western pattern. The structural type comprises two type that a pure structure and a mixed structure, and Korean traditional structure is a mixed structure more than a pure structure. It is considered continuous changes by a resident due to a pure structure was not satisfy various functions. It need appropriate plan to improve a rural residence for each characteristics.

• Journal of the Korean Chemical Society
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• v.50 no.1
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• pp.53-59
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• 2006

.FAPO-5 molecular sieves were synthesized starting from the same reactant gel at 170 oC using microwave irradiation technique and conventional hydrothermal reaction. The FAPO-5 molecular sieves were characterized by several techniques such as SEM, FTIR, UV/Vis, and ESR. Moreover, the oxidation of styrene over FAPO-5s was carried out, and compared to check the oxidation and epoxidation ability of the two FAPO-5s. FAPO-5 can be obtained easily by microwave irradiation within 15 min at 170oC, whereas FAPO-5 synthesis is completed in 6 h by conventional electric heating, confirming the acceleration about 20 times by microwave technique. There are no appreciable differences between two FAPO-5s in surface area and coordination state of iron. The FAPO-5 synthesized by microwave irradiation shows higher epoxide selectivity in the styrene epoxidation, which may be explained by the higher hydrophobicity of the catalyst.