• New & Renewable Energy
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• v.16 no.2
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• pp.47-53
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• 2020

The amount of food waste and its water content depends on both the season and region. In particular, the water content typically varies between 73.8 wt.% and 83.3 wt.%, depending on the proportion of vegetables. Current food waste drying technologies are capable of reducing the water content to less than 10 wt.%, while increasing the heating value. Ongoing studies aim to utilize dried food waste as fuel. Food waste can be used to produce solid refuse fuel (SRF) by mixing it with various solid fuels or other types of waste. The analysis of specimens is very important when considering the direct combustion of food waste or its co-firing with solid fuels. In this study, the weight reduction of specimens after burning them in a small combustor, and compared with the results of thermogravimetric analysis (TGA). The concentration of various chemicals was also measured to define the characteristics of waste generation. Performed proximate analysis, elemental analysis, TGA, combustion experiment, the heating value, and derivative thermogravimetry (DTG).

• Applied Microscopy
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• v.41 no.2
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• pp.81-88
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• 2011

Even though importance of nano-scale structure and compositional analysis have been getting increased, existing analysis tools have been reached to their limitations. Recent development of Atom Probe Tomography (APT), providing 3-dimensional elemental distribution and compositional information with sub-nm scale special resolution and tens of ppm detection limit, is one of key technique which can overcome these limitations. However, due to the fact that APT is not well known yet in the domestic research area, it has been rarely utilized so far. Therefore, in this article, the theoretical background of APT was briefly introduced with sample preparation to help understanding APT analysis.

• Journal of Energy Engineering
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• v.20 no.1
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• pp.36-43
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• 2011

Plant biomass has been proposed as an alternative source of petroleum-based chemical compounds. Especially, aromatic chemical compounds can be obtained from lignin by depolymerization processes because the lignin consist of complex aromatic materials. In this study, kraft lignin, the largest emitted substance among several kinds of lignin in Korea, was used as a starting material and was characterized by solid-state $^{13}C$-Muclear Magnetic Resonance($^{13}C$-NMR), Fourier Transform Infrared Spectroscopy(FT-IR), Elemental Analysis(EA). The depolymerization of kraft lignin was studied at water-phenol mixture solvent in near critical region and the experiments were conducted using a batch type reactor. The effects of water-to-phenol ratio and reaction temperature($300-400^{\circ}C$) were investigated to determine the optimum operating conditions. Additionally, the effects of formic acid as a hydrogen-donor solvent instead of $H_2$ gas were examined. The chemical species and quantities in the liquid products were analyzed using gas chromatography-mass spectroscopy(GC-MS), and solid residues(char) were analyzed using FT-IR. GC-MS analysis confirmed that the aromatic chemicals such as anisole, o-cresol(2-methylphenol), p-cresol(4-methylphenol), 2-ethylphenol, 4-ethylphenol, dibenzofuran, 3-methyl cabazole and xanthene were produced when phenol was added in the water as a co-solvent.

• Analytical Science and Technology
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• v.14 no.2
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• pp.131-139
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• 2001

There is personal difference in the concentrations of trace elements in human hair according to human life or history suck as occupation, race, sex, age, food habit, social condition and so on. It is also found that the individual's deviation of elemental concentrations is reflecting the degree of environmental pollutants exposure to human body, intakes of food and metabolism. To compare the degree of accumulation in the hair tissue, human hair samples were collected from five positions of head and analyzed by non-destructive neutron activation analysis with and without washing according to IAEA's recommended method. Analytical quality control is performed using the certified reference material. The relative error of Cu, Cr, Na, Co, Mg, As, Se, Zn and those of Mn, Ca, Fe, Sr are within ${\pm}5%$ and ${\pm}10%$, respectively and the relative standard deviation of elements are within ${\pm}10%$. The deviations between the individuals and hair sampling positions were estimated. The deviation of individual was seven times more than that of positions. Under the defined condition, the difference and the correlation of elemental concentrations were compared with two different groups, office and factory workers. The result can be used as a fundamental data for human health and environment assessment.

• Polymer(Korea)
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• v.38 no.2
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• pp.257-264
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• 2014

In this study, we modified silica nanoparticles with bis[3-(trimethoxysilyl)propyl]ethylenediamine (BTPED) silane coupling agent, which has two secondary amino groups in a molecule, to introduce amino groups on the silica surface. After modification of silica, we used acrylate group containing 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM) to introduce polymerizable methacrylate groups by Michael addition reaction. We used Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA) and liquid and solid state cross polarization magic angle spinning (CP/MAS) nuclear magnetic resonance spectroscopy (NMR) to understand the reactions between N-H groups of BTPED modified silica surface and acrylate groups of AHM monomer. We confirmed Michael addition reaction between BTPED modified silica and AHM completed in 2 hr reaction time. We also found increased methacrylate group introduction with increase of mol ratio of the acrylate group of AHM to N-H group of BTPED modified silica by increase of C=O peak area of measured FTIR spectra. These results were also supported by EA and solid state $^{13}C$ and $^{29}Si$ NMR results.

• Journal of Periodontal and Implant Science
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• v.32 no.3
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• pp.615-630
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• 2002

Various long-term studies have shown that titanium implants as abutments for different types of prostheses have become a predictable adjunct in the treatment of partially or fully edentulous patients. The continuous exposure of dental implants to the oral cavity with all its possible contaminants creates a problem. A lack of attachment, together with or caused by bacterial insult, may lead to peri-implantitis and eventual implant failure. Removal of plaque and calculus deposits from dental titanium implants with procedures and instruments originally made for cleaning natural teeth or roots may cause major alterations of the delicate titanium oxide layer. Therefore, the ultimate goal of a cleaning procedure should be to remove the contaminants and restore the elemental composition of the surface oxide without changing the surface topography and harming the surrounding tissues. Among many chemical and mechanical procedure, air-powder abrasive have been known to be most effective for cleaning and detoxification of implant surface. Most of published studies show that the dental laser may be useful in the treatment of pen-implantitis. $CO_2$ laser and Soft Diode laser were reported to kill bacteria of implant surface. The purpose of this study was to obtain clinical guide by application these laser to implant surface by means of Non-contact Surface profilometer and X-ray photoelectron spectroscopy(XPS) with respect to surface roughness and atomic composition. Experimental rough pure titanium cylinder models were fabricated. All of them was air-powder abraded for 1 minute and they were named control group. And then, the $CO_2$ laser treatment under dry, hydrogen peroxide and wet condition or the Soft Diode laser treatment under Toluidine blue O solution condition was performed on the each of the control models. The results were as follows: 1. Mean Surface roughness(Ra) of all experimental group was decreased than that of control group. But it wasn't statistically significant. 2. XPS analysis showed that in the all experimental group, titanium level were decreased, when compared with control group. 3. XPS analysis showed that the level of oxygen in the experimental group 1, 3($CO_2$ laser treatment under dry and wet condition) and 4(Soft Diode laser was used under toluidine blue O solution) were decreased, when compared with control group. 4. XPS analysis showed that the atomic composition of experimental group 2($CO_2$ laser treatment under hydrogen peroxide) was to be closest to that of control group than the other experimental group. From the result of this study, this may be concluded. Following air-powder abrasive treatment, the $CO_2$ laser in safe d-pulse mode and the Soft Diode laser used with photosensitizer would not change rough titanium surface roughness. Especially, $CO_2$ laser treatment under hydrogen peroxide gave the best results from elemental points of view, and can be used safely to treat peri-implantitis.

• Journal of the Korean Wood Science and Technology
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• v.36 no.4
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• pp.44-51
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• 2008

In this study, the effects of carbonization temperature on the physico-chemical properties of Korean red-pine wood (Pinus densiflora S. et Z.) powder charcoal are studied by elemental analysis, nitrogen adsorption-desorption and SEM techniques. The surface structure and physico-chemical properties of the wood charcoal greatly depend on the carbonization temperature and their temperature dependences for sapwood (swd) and heartwood (hwd) are qualitatively analogous. Because of the differences in characteristics such as hardness and composition between heartwood and sapwood, charcoals from heartwood have larger specific surface area and smaller average pore diameter than that from sapwood. Because the decomposition reaction mostly proceeds in the precarbonization stage, the charcoal produced in this stage mainly consists of carbon. The second carbonization reaction is insignificant but still proceeds up to $700^{\circ}C$, and the specific surface area continuously increases. Above $800^{\circ}C$, the surface area is reduced by the pore-filling and narrowing effects and especially above $900^{\circ}C$, new carbon phase with hexagonal column rooted into the pore is formed. The nitrogen adsorption-desorption isotherm of the charcoal is classified as type I and its hysteresis loop was as type H4.

• Polymer(Korea)
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• v.36 no.5
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• pp.668-676
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• 2012

In this study, we modified silica nanoparticles with bis[3-(trimethoxysilyl)propyl]amine (BTMA) silane coupling agent to introduce secondary amino groups on the silica surface. After modification of silica, we investigated effects of different types of (meth)acrylate group containing monomers on the Michael addition reaction to introduce reactive (meth)acrylate groups on the BTMA modified silica surface. We used two kinds of (meth)acrylate monomers, trimethylolpropane ethoxylate triacrylate (TMPET) which has three identical acrylate groups, and 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM) which has one acrylate and one methacrylate group. We used fourier transform infrared spectroscopy (FTIR), elemental analysis (EA) and solid state cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance spectroscopy (NMR) to understand reactions between NH groups on the silica surface with (meth)acrylate groups of TMPET and AHM monomers. We found almost complete Michael addition reaction between all three acrylate groups of TMPET with NH groups on the BTMA modified silica. But, for the AHM treatment of BTMA modified silica, we found Michael addition reaction occurred only between acrylate groups of AHM and NH groups of silica surface, not between methacrylate groups of AHM and NH groups of BTMA modified silica surface.

• Journal of the Korean Wood Science and Technology
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• v.42 no.3
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• pp.266-274
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• 2014

To extend the understanding of the pyrolysis mechanism of wood, we have investigated wood dust charcoal and condensate of volatile organic compounds (VOC) obtained during the pyrolysis of red pine (Pinus densiflora Sieb. et Zucc.) at $180{\sim}450^{\circ}C$ using elemental analysis, IR and GC/Mass. The effect of activation process on the charcoal structure also has been studied by comparing elemental analysis and IR data of charcoal carbonated at $600^{\circ}C$ and charcoals activated at $750^{\circ}C$. The results show that pyrolysis of wood has mainly started near at $240^{\circ}C$ and its chemical components did not changed much up to $270^{\circ}C$. However, the element contents and IR spectra drastically changed at $300^{\circ}C$. The fact that IR peaks related to the aromatic ring of lignin are observed in the charcoal pyrolized at $450^{\circ}C$ indicates that a small part of lignin still remains at this temperature. The chemical structure of the activated charcoal seems almost unaffected by the activation time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.10
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• pp.747-751
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• 2010

In the study, the characteristics of the etched Zinc oxide (ZnO) thin films surface, the etch rate of ZnO thin film in $Cl_2/BCl_3/Ar$ plasma was investigated. The maximum ZnO etch rate of 53 nm/min was obtained for $Cl_2/BCl_3/Ar$=3:16:4 sccm gas mixture. According to the x-ray diffraction (XRD) and atomic force microscopy (AFM), the etched ZnO thin film was investigated to the chemical reaction of the ZnO surface in $Cl_2/BCl_3/Ar$ plasma. The field emission auger electron spectroscopy (FE-AES) analysis showed an elemental analysis from the etched surfaces. According to the etching time, the ZnO thin film of etched was obtained to The AES depth-profile analysis. We used to atomic force microscopy to determine the roughness of the surface. So, the root mean square of ZnO thin film was 17.02 in $Cl_2/BCl_3/Ar$ plasma. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the plasmas.