• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.23-28
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• 2017

Pyrolysis characteristics of waste plastic films were investigated by using a thermogravimetric analysis and pyrolyzer-gas chromatography/mass spectrometry. Thermogravimetric analysis results revealed that the pyrolysis of waste plastic films can be divided into two distinct reactions; (1) the decomposition reaction of starch at between 200 and $370^{\circ}C$ and (2) that of other plastic polymers such as PS, PP, PE at between 370 and $510^{\circ}C$. The kinetic analysis results obtained by using the revised Ozawa method indicated that the apparent activation energy of the pyrolysis reaction of waste plastic films was also changed dramatically according to the different decomposition reactions of two major waste plastic film components. Py-GC/MS results also revealed that the typical pyrolyzates of each polymer in waste plastic films were levoglucosan (starch), terephthalic acid (PET), styrene monomer, dimer, and trimer (PS), methylated alkenes (PP), and triplet peaks (PE) composed of alkadiene/alkene/alkane. The phthalate, used as a polymer additive, was also detected on the pyrogram of waste plastic films mixture.

• Journal of Life Science
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• v.25 no.5
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• pp.577-584
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• 2015

Orostachys malacophyllus grow on the old roofing tile or on the rock of mountain and is belong to Crassulaceae family. After air drying for Orostachys malacophyllus (OM), using the mixture of lactic acid bacteria (Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus) was fermented (FOM). OM and FOM extracted using water (W), ethanol (E) and methanol (M) and were measured extracts yield, pH and Brix. Extracted OM and FOM were tested by in vitro experimental models of α,α´-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging activity, Fe/Cu reducing power, linoleic acid peroxidation using ferric thiocyanate and thiobarbituric acid (TBA) methods and peroxidation of rat liver homogenate. In addition, the bioactive materials (phenolic compounds, flavonoids and minerals) were measured. The highest phenolic compounds and flavonoids were OME 122.2 mg/100 g and OME 84.0 mg/100 g. OM and FOM′s major minerals were K, Ca and Mg. The highest free radical scavenging activity showed in FOMM (93.9%), OMM (93.4%), FOME (92.1%) and OME (91.9%) at 0.5% additional level. Fe reducing powers were strong in FOME and FOMM and Cu reducing powers were strong in OME and FOMM. Antioxidant activities on lipid peroxidation using rat homogenate as measured by TBARS method showed strong in FOME and on lipid peroxidation of linoleic acid as measured by ferric TBA method showed strong in OME and FOME and measured by ferric thiocyanate showed strong in FOME and FOMM.

• Korean Journal of Food Science and Technology
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• v.27 no.1
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• pp.134-140
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• 1995

Four different mashes using traditional methods in Korea such as Andong soju, Moonbaeju, Leekangju and Jindo hongju, were prepared for distilled liquor. The changes of pH, total acid, reducing sugar, total sugar, alcohol, solid content and ${\beta}-amylase$ activities in their mashes were studied during fermentation. Ethanol content of mashes were increased to the range of $8.8{\sim}11.2%$ after 16 days of fermentation. The group which was brewed by the first addition of mash showed higher ethanol content than the other group which was not added the ones. Total acid content of mashes increased to $0.59{\sim}1.10%$. The total sugar content was decreased to $6.70{\sim}8.94%$, and that of Leekangju type was lower than that of other fermented mashes. Reducing sugar content was in the range of $0.62{\sim}6.42%$ at the initial fermentation and decreased to $0.09{\sim}0.30%$ after 16 days of fermentation. Soju was obtained by distillation of each fermented mashes using the modified traditional Togori. After distillation of mashes, pH was increased and total acid was reduced. Sugar(3.58%) and solid(1.17%) in Leekangju were found to be leached from the mixture of pear, ginger, cinnamon, honey and curcuma rhizome.

• Journal of the Korean GEO-environmental Society
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• v.13 no.10
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• pp.25-32
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• 2012

The application of electrical resistivity, which is related to charge mobility, has increased in the field of geotechnical engineering for the detection of underground cavern, faults and subsurface pollution level. The purpose of this study is to investigate the variation of electrical resistivity due to temperature change. Sand-silt mixture specimens prepared in the square freezing nylon cell are frozen in the frozen chamber. Four electrodes are attached on the four side walls of the freezing cell for the measurement of electrical resistance during temperature change. Electrical resistances of sand-silt mixtures with different degrees of saturation (0%, 2.5%, 5%, 10%, 20%, 40%, 60% and 100%) are measured as the temperature of specimens decrease from $20^{\circ}C$ to $-10^{\circ}C$. The electrical resistances determined by Ohm's law are transformed into the electrical resistivity by calibration. Experimental results show that the higher degree of saturation, the lower electrical resistivity at $20^{\circ}C$. Electrical resistivity gradually increases as the temperature decrease from $20^{\circ}C$ to $0^{\circ}C$. For the specimens with the degree of saturation of 15% or higer, electrical resistivity dramatically changes near the temperature of $0^{\circ}C$. In addition, very high electrical resistivity is observed regardless of the degree of saturation if the specimens are frozen. This study provides the fundamental information of electrical resistivity according to the soil freezing and temperature change demonstrates that electrical resistivity be a practical method for frozen soil investigation.

• Journal of the Korean Geosynthetics Society
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• v.12 no.1
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• pp.73-81
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• 2013

The objective of this paper is to minimize installation length of pipeline and to reduce burial depth for construction by increasing the friction coefficient caused by the interface between backfill material and pipeline. And then, the sufficient friction coefficient shortens the length of expansion joint pipe and gives the life extension of expansion joint absorber for efficient procedure regarding maintenance and administration of construction. The backfill material which is developed in this study has larger and smaller friction angle than that of conventional backfill material (river sand). The backfill material with tire powder provides low friction angle at curved section when pipe diameter increases in size (38% reduction at pipe diameter in 900 mm). When using backfill material with river sand and fly-ash, the mixture mixed with 1.5% fly-ash has 30% and that with 3% fly-ash has 50% reduction effect for minimum installation length of expansion joint pipe.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.3
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• pp.284-294
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• 2006

Statement of problem. Proliferation of Candida albicans is primarily within the plaque on the fitting surface of the denture rather than on the inflamed mucosa. Consequently, the treatment of the denture is equally important as treatment of the tissue. Cleansing and disinfection should be efficiently carried-out as the organisms can penetrate into the voids of the acrylic resin and grow in them, from which they can continue to infect and reinfect bearing tissues. Purpose. The purpose of this study was to evaluate the applicability of photocatalytic reaction to eliminate Candida albicans from acrylic resin denture base, and to investigate the anti-fungal effect with various UVA illumination time. Materials and Methods. The specimens were cured by the conventional method following the manufacturer's instruction using thermal polymerized denture base resin (Vertex RS: Dentimex, Netherlands). $TiO_2$ photocatalyst sol(LT), which is able to be coated at normal temperature, was made from the Ti-alkoxide progenitor. The XRD patterns, TEM images and nitrogen absorption ability of the $TiO_2$ photocatalyst sol(LT) were compared with the commercial $TiO_2$ photocatalyst P-25. The experimental specimens were coated with the mixture of the $TiO_2$ photocatalyst sol(LT) and binder material (silane) using dip-coater, and uncoated resin plates were used as the control group. Crystallinity of $TiO_2$ of the specimen was tested by the XRD. Size, shape and chemical compositions were also analyzed using the FE-SEM/ EDS. The angle and methylene blue degradation efsciency were measured for evaluating the photocatalytic activity of the $TiO_2$ film. Finally, the antifungal activity of the specimen was tested. Candida albicans KCTC 7629(1 ml, initial concentration $10^5$ cells/ ml) were applied to the experiment and control group specimens and subsequently two UVA light source with 10W, 353 nm peak emission were illuminated to the specimens from 15cm above. The extracted $2{\mu}l$ of sample was plated on nutrient agar plate ($Bacto^{TM}$ Brain Heart Infusion; BD, USA) with 10 minute intervals for 120 minute, respectively. It was incubated for 24 hours at $37^{\circ}C$ and the colony forming units (CFUs) were then counted. Results. Compared the characteristics of LT photocatalyst with commercial P-25 photocatalyst, LT were shown higher activity than P-25. The LT coated experimental specimen surface had anatase crystal form, less than 20 nm of particle size and wide specific surface area. To evaluate the photocatalytic activity of specimens, methylene blue degradation reaction were used and about 5% of degradation rate were measured after 2 hours. The average contact angle was less than $20^{\circ}$ indicating that the LT photocatalyst had hydrophilicity. In the antifungal activity test for Candida albicans, 0% survival rate were measured within 30 minute after irradiation of UVA light. Conclusion. From the results reported above, it is concluded that the UVA-LT photocatalytic reaction have an antifungal effect on the denture surface Candida albicans, and so that could be applicable to the clinical use as a cleaning method.

• Elastomers and Composites
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• v.48 no.2
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• pp.94-102
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• 2013

Characteristics of rubber mixture were evaluated in order to find the optimum mixing conditions of compounds containing silica and silane at various temperatures. With different mixing temperatures of 105, 120, 130, 140 and $160^{\circ}C$, the viscosity of the compound mixed at $105^{\circ}C$ showed a very high viscosity value. Compounds mixed the temperature range from at $120^{\circ}C$ to $140^{\circ}C$ showed lower viscosity than the compound mixed at $105^{\circ}C$. However, the difference was found to be small in those temperature ranges. On the contrary, at the mixing temperature of $160^{\circ}C$, the viscosity of compound increased again. Through the physical and dynamic observations, it was verified that at the mixing temperature below $120^{\circ}C$ only insufficient silica-silane reaction has been obtained. In addition, with the elevated mixing temperature of $160^{\circ}C$, Cross-linking occurred during mixing by the sulfur contained in coupling agent. In the temperature ranges from $120^{\circ}C$ to $140^{\circ}C$, because of the fast coupling reaction at higher temperature, it was thought to be more advantageous during reaction even though the trend of viscosity and dynamic mechanical property was not clear.

• Korean Journal of Agricultural Science
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• v.7 no.2
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• pp.156-168
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• 1980

The air-center nozzles, being specially designed to supply air into the central part of water stream at seven levels of air volume, were tested for spray deposit pattern and flow-rate at each of the twelve pressure levels ranging from $0.35kg/cm^2$ (5 psi) to $6.33kg/cm^2$ (90 psi) in comparison with those of standard nozzles. The air-center nozzles produced comparatively more stable spray deposit patterns than the standard nozzles. The spray deposit patterns of the air-center nozzle were concentrated gradually in the central region with increase of air volume as a component of spray mixture. The degree of concentration of spray deposit on the central region from the air-center nozzle was higher than that of the standard nozzle, which suggested the possibility of obtaining farther travel distance spraying system at a given performance level. The flow rate of the air-center nozzle was not as much as that of the standard nozzle due to the air within certain limits. The rate of decrease of water flow became smaller with an increase in operating pressure although it changed rapidly in the beginning stage, ranging up to two or three percent of the air flow rate due to the compressive properties of air.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.720-730
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• 1997

This study was performed to observe the histopathological response to the bonding resin directly applied on the remaining pulp tissues. 40 teeth from 3 adult dogs were pulpotomized with a sterile round bur and sharp excarvater. In the control group, $Ca(OH)_2$ powder was applied on the pulp tissue and the cavities were sealed with IRM cement. In the experimental group 1, Superbond C&B was applied on the remaining pulp and the cavities conditioned with 10-3 solution were filled with the mixture of the MMA liquid, PMMA powder and Catalyst. Multi-purpose adhesive was used on the remaining pulp tissue in the experimental group 2 and Z-100 was filled in the cavities. In the experimental group 3, Clearfil photobond applied and directly photo-cured on the pulp tissue, then the cavities were treated with CA agent (10% citric acid and 20% $CaCl_2$ aqueous solution) for 20 seconds, washed and applied with Clearfil photobond then filled with Protect liner. The experimental animals were sacrified at the 1st, 2nd, and 4th week. The specimens were routinely processed and stained with H-E for light microscopic observation. The results were as followed : 1. In the experimental group 1, the number and characteristics of the dentin bridge formation case was similar to those in the control group and less cases were observed in the experimental group 2 and 3 than experimental group 3. The inflammatory response in experimental group 1 was less than that in the control group at 1st week but there had been little difference at between 2nd and 4th week. 2. The number of the dentin bridge in experimental group 2 was less than that in control group and experimental group 1. The inflammatory response of the experimental group 1 was similar to that of experimental group 1 but less than that of the control group. A number of bleeding and vascular congestion were observed. The least inflammatory response was seen in the experimental group 2 among all groups. 3. In the experimental group 3, one case of the dentin bridge formation was observed and that was the same as that in the experimental group 2 but smaller than that of the control and experimental group 1. The inflammatory response of the experimental group 3 was least at the 1st week and most at the 4th week in the all group.

• Food Science and Preservation
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• v.9 no.1
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• pp.28-35
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• 2002

This study was conducted to evaluate the quality characteristics of different soy sauces. The soybean sauces brewed tty the A. oryzae koji(SAO), M. pilosus-1 koji(SMP) and the mixture of 50% M. pilosus-1 koji(SAM) during 90 days fermentation. Total nitrogen contents of the SAM, SAP and SMP were 13.6%, 1.15% and 1.22%, respectively. Content of amino type nitrogen in SAM was 0.78%, and the content was higher than those of SAO and SMP. Total free amino acid contents of SAO, SMP and SAM were 533.8, 732.4 and 807.3 mg/100 mL. The highest contents of free, amino acids were glutamic acid(65.20 mg/100 mL) in SAG, alanine(101.42 mg/100mL) in SMP, glutamic acid(130.52 mg/100 mL) in SAM. The highest activities of pretense and ${\beta}$-amylase showed in SAM, and the lowest activities of ${\alpha}$-amylase and glucoamylase were in SAO and SMP respectively. Hue angle values showed 56.3 in SAO, 29.0 in SMP and 32.2 in SAM. Monacolin K contents, as inhibitor of cholesterol bio-synthesis were 6.21 $\mu\textrm{g}$/mL for SMP and 3.10 $\mu\textrm{g}$/mL for SAM, and the inhibitory activities of SMP ane SAM aginst HMG-CoA reductase were 21.5 md 10.2%, respectively. Sensory scores for color, flavor, savory taste and overall taste of SAM was higher than those of SAO and SMP.