• Carbon letters
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• v.16 no.4
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• pp.233-240
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• 2015

Electrochemical synthesis was employed to prepare a novel hydroxyapatite/graphene (HAP/Gr) composite powder suitable for medical applications as a hard tissue implant (scaffold). The synthesis was performed in a homogeneous dispersion containing Na₂H₂EDTA·2H₂O, NaH₂PO₄ and CaCl₂ with a Ca/EDTA/PO₄³⁻ concentration ratio of 0.25/0.25/0.15M, along with 0.01 wt% added graphene nanosheets, at a current density of 137 mA cm⁻² and pH value of 9.0. The field emission scanning electron microscopy and transmission electron microscopy observations of the composite HAP/Gr powder indicated that nanosized hydroxyapatite particles were uniformly placed in the graphene overlay. Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction confirmed graphene incorporation in the HAP/Gr powder. The electrochemically prepared HAP/Gr composite powder exhibited slight antibacterial effect against the growth of the bacterial strain Staphylococcus aureus.

• The Journal of Korean Academy of Prosthodontics
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• v.27 no.1
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• pp.123-141
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• 1989

The purpose of this study was to investigate the tendency of color change of ceramic, and its mechanism un der the influence of Pd-Ag alloy. The specimens were made by firing porcelain on tile metal plates cast with Au-Pt alloy, Pd-Cu alloy and Pd-Ag alloy. In the case of Pd-Ag alloy, specimens were fired under three different conditions as follows, 1) without protection, 2) protection with ceramic metal conditioner, 3) protection with carbon block. For the specimens of element analysis, a barrier was constructed with platinum foil between metal plate and ceramic. Color change was measured with colorimeter and elemental changes in ceramic were calculated with DC argon plasma emission spectrophotometer. The results were as follows : 1. Color change of ceramic by Pd-Ag alloy was negligible in hue, but decreased in value and increased in chroma (yellow discoloration). 2. Color change of ceramic by Pd-Ag alloy was appeared through vapor transport mechanism. 3. As the protection method for the color change of ceramic by Pd-Ag alloy, application of ceramic metal conditioner was superior to utilization of carbon block.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.1
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• pp.53-63
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• 2012

As a result of the economical loss caused by unusual climate changes resulting from emission of excessive green house gases such as carbon dioxide which is expected to account for 5~20% of the world GDP by 2100, researching technologies regarding the reduction of carbon dioxide emission is being favored worldwide as a part of the high value-added industry. As one of the Annex II countries of Kyoto Protocol of 1997 that should keep the average $CO_2$ emission rate of 5% by 2013, South Korea is also dedicated to the researches and industries of $CO_2$ emission reduction. In this study, Application of LiDAR data & KOMPSAT-2 satellite image for calculated forest Biomass. Raw LiDAR data's tree numbers and tree-high with field survey data resulted in 90% similarity of objects and an average of 0.3m difference in tree-high. Calculating the forest biomass through forest type information categorized as KOMPSAT-2 image and LiDAR data's tree-high data of tree enabled the estimation of $CO_2$ absorption and forest biomass of forest type, The similarity between the field survey average of 90% or higher were analyzed.

• Clean Technology
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• v.18 no.3
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• pp.229-249
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• 2012

At present, global warming and depletion of fossil fuels have been one of the big issues which should be solved for sustainable development in the future. CCS (carbon capture and sequestration) technology as the post $CO_2$ reduction technology has been considered as a promising solution for global warming due to increased carbon emission. However, the environmental and ecological effects of CCS have drawn concerns. There are needs for noble post reduction technology. More recently, CCU (carbon capture and utilization) Technology, which emphasizes transforming carbon dioxide into value-added chemicals rather than storing it, has been attracted attentions in terms of preventing global warming and recycling the renewable carbon source. In this paper, various technologies developed for carbon dioxide conversion both in gas and liquid phase have been reviewed. For the thermochemical catalysis in gas phase, the development of the catalytic system which can be performed at mild condition and the separation and purification technology with low energy supply is required. For the photochemical conversion in liquid phase, efficient photosensitizers and photocatalysts should be developed, and the photoelectrochemical systems which can utilize solar and electric energy simultaneously are also in development for more efficient carbon dioxide conversion. The energy needed in CCU must be renewable or unutilized one. CCU will be a key connection technology between renewable energy and bio industry development.

• Spatial Information Research
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• v.23 no.2
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• pp.11-20
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• 2015

Abstract Monitoring is the most critical element in implementing "forest carbon offset project" to enhance the visibility of CSR (Corporate Social Responsibility) in North Korea. This study is intended to explore monitoring potential in terms of forest carbon offset project using satellite image for Baekdu mountain of North Korea. The permanent record of standard satellite remote sensing system demonstrated its capability of presenting area-wide visual evidences of monitoring conditions in Mt. Baekdu mountain of North Korea (site suitability, carbon stock by forest biomass growth, carbon emission by forest biomass loss, deforestation and degradation, environmental, social and economic impact specified in the Carbon Sequestration Law). It doesn't seem very difficult to comply with monitoring requirements for "the forest carbon offset project" due to the probative value of satellite data. Therefore, it could be considerable or realistic approach to utilize CSR based forest carbon offset project as a point of reform and open-door in North Korea. It is anticipated that this research output could be used as a valuable reference for Korea-based enterprises to ensure monitoring potentials using satellite image in exploring forest carbon offset project sites in North Korea.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.04a
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• pp.131-138
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• 2011

Currently, many forest residues have been generated by the National Forest Management Operation. Unfortunately, most of the forest residues are supposed to be used as raw materials for burning fuels like wood pellets. Even though the forest biomass must be effectively used for making high value-added products, they may be subject to disposable raw materials for wood pellets. Wood pellets are regarded as burning fuels with less contribution to the decrease in carbon gas emission, compared to raw materials for kraft pulps. In this study, we studied whether or not forest biomass mixed with various ages and, species could be used as raw materials for kraft pulps.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1008-1011
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• 2005

In this study, the field emission display with carbon nanotube emitter is developed for the large size HDTV application. Two structures for electron beam focusing are developed on the typical top-gate cathode. The metal grid and focusing gate structure are proved to be effective for the focusing. The data switching voltage for the double gate structure is lower than 30V which is competitive value in respect of the cost for driver electronics. The brightness and color gamut are comparable to those of the commercial product such as CRT.

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.548-555
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• 2017

This study investigated the influence of air staging on combustion and NOx emission in a tangential-firing boiler at a 560 MWe capacity. For air staging, the stoichiometric ratio (SR) for the burner zone was varied from 0.995 to 0.94 while the overall value was fixed at 1.2. The temperature and heat flux in the burner zone and upper furnace corresponded to the distribution of SR, while the total boiler efficiency remained similar. The NOx emission at the furnace exit was reduced by up to 20% when the SR in the burner zone decreased to 0.94. However, the amount of unburned carbon and slagging propensity was not noticeably influenced by the changes in the SR of the burner zone. Therefore, it was favorable to lower the SR of the burner zone for reduction of NOx emission.

• Smart Structures and Systems
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• v.17 no.1
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• pp.91-105
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• 2016

One of the most commonly used techniques to strengthen steel reinforced concrete structures is the application of externally bonded patches in the form of carbon fiber reinforced polymers (CFRP) or recently, textile reinforced cements (TRC). These external patches undertake the tensile stress of bending constraining concrete cracking. Development of full-field inspection methodologies for fracture monitoring are important since the reinforcing layers are not transparent, hindering visual observation of the material condition underneath. In the present study acoustic emission (AE) and digital image correlation (DIC) are applied during four-point bending tests of large beams to follow the damage accumulation. AE helps to determine the onset of fracture as well as the different damage mechanisms through the registered shifts in AE rate, location of active sources and change in waveform parameters. The effect of wave propagation distance, which in large components and in-situ can well mask the original information as emitted by the fracture incidents is also discussed. Simultaneously, crucial information is supplied by DIC concerning the moments of stress release of the patches due to debonding, benchmarking the trends monitored by AE. From the point of view of mechanics, conclusions on the reinforcing contribution of the different repair methodologies are also drawn.

• Journal of Biosystems Engineering
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• v.34 no.6
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• pp.446-453
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• 2009

This study was conducted to find condition of improving the quality of peach by using surfacing washing system. The rate of weight loss of A,B groups were showed slower decreasing trend than CT group and the value of soluble solid degree was not different significantly among all groups from the results of stored peach treat with surface washing system of peach in the first experiment. The colory value of surface were increased with increasing storage period in all treatments. Browning pace of A,B groups were slower than control. Emission of carbon dioxide was increased from the results of respiration rate, 6-10 mL/kg/hr $(10^{\circ}C)$ and 32-41 mL/kg/hr $(25^{\circ}C)$. In second experiment with surface washing system of peach, the value of soluble solid was showed with similar value from 10 $Brix^{\circ}$ to 13 $Brix^{\circ}$. The pace of soft rot of EW groups were lower than CT groups from the results of hardness during storage period. The results of colory value was not showed with significant difference in $15^{\circ}C$ and $20^{\circ}C$ storage temperature but changed to browning in EW groups. The moisture contents was from 85% to 90% in all groups. And the count of total microorganism of EW groups were lower than control. Also total coliform of EW groups were negative. In sensory evaluation, washing peach was showed higher value with significant difference in all acceptability.