• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.3
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• pp.205-215
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• 2002

This study investigated the compressive fracture strength of Targis ceromer crown by the difference of occlusal thickness on a maxillary first premolar. Control group was a castable IPS-Empress all-ceramic crown with occlusal thickness of 1.5 mm constructed by layered technique. Experimental groups were Targis crowns having different occlusal thicknesses of 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, respectively. The classification of Targis group is T10, T15, T20, T25 and T15N (for no-thermocycling and occlusal thickness of 1.5mm). Ten samples were tested per each group. Except occlusal thickness, all dimension of metal die is same with axial inclination of $10^{\circ}$and marginal width 0.8mm chamfer. All crowns were cemented with Panavia F and thermocycled 1,000 times between $5^{\circ}$ and $55^{\circ}$ water bath with 10 sec dwelling time and 10 sec resting time. The compressive fracture strength was measured by universal testing machine. The results were as follows : 1. Fracture strength was increased as the occlusal thickness increased : compressive fracture strength of Group T10, T15, T20, T25 was $66.65{\pm}4.88kgf$, $75.04{\pm}3.01kgf$, $87.07{\pm}7.06kgf$ and $105.03{\pm}10.56kgf$, respectively. 2. When comparing material, Targis crown had higher fracture strength than IPS-Empress crown : the mean compressive strength of group T15 was $75.04{\pm}3.01kgf$ and the value of group Control was $37.66{\pm}4.28kgf$. 3. Fracture strength was decreased by thermocycling : the compressive fracture strength of T15 was $75.04{\pm}3.01kgf$, which is lower than $90.69{\pm}6.88kgf$ of group T15N. 4. The fracture line of crowns began at the loading point and extended along long axis of tooth. IPS-Empress showed adhesive failure pattern whereas Targis had adhesive and cohesive failure. In the SEM view, stress was distributed radially from loading point and the crack line was more prominent on Targis crown.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.2
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• pp.114-118
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• 2017

Purpose: The aim of this study was to investigate the effects of a titanium component for the zirconia abutment in the internal connection implant system on screw loosening under thermocycling conditions. Materials and Methods: Internal connection titanium abutments and external connection zirconia abutments with titanium sockets were connected respectively to screw-shaped internal connection type titanium implants with 30 Ncm tightening. These implant-screw-abutment assemblies were divided into two groups of five specimens each; titanium abutments as control and zirconia abutments with titanium sockets as experimental group. The specimens were subjected to 2,000 thermocycles in water baths at $5^{\circ}C$ and $55^{\circ}C$, with 60 seconds of immersion at each temperature. The removal torque values (RTVs) of the abutment screws of the specimen were measured before and after thermocycling. RTVs pre- and post-thermocycling were investigated in statistics. Results: There was not screw loosening identified by tactile and visual inspection in any of the specimens during or after thermocycling. The mean RTV difference for the control group and the experimental group were $-1.34{\pm}2.53Ncm$ and $-1.26{\pm}2.06Ncm$, respectively. Statistical analysis using an independent t-test revealed that no significant differences were found in the mean RTV difference of the groups (P > 0.05). Conclusion: Within the limitations of this in vitro study, the titanium socket for the zirconia abutment did not show a significant effect on screw loosening under thermal stress compared to the titanium abutment in the internal connection implant.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.11
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• pp.1635-1641
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• 2014

Diospyros lotus has been cultivated for its edible fruits, which are considered to have medicinal importance. The aim of this study was to evaluate the antioxidant and antipruritic activities of water-soluble, methanol extract, and ethyl acetate (EA) fractions from D. lotus leaves. The EA fraction showed the lowest $IC_{50}$ vale (DPPH: $5.3{\mu}g/mL$, ABTS: $53.8{\mu}g/mL$). Therefore, we further investigated anti-inflammatory and antipruritic effects of the EA fraction. TNF-${\alpha}$ production increased by PMA plus A23187 treatment was significantly inhibited by the EA fraction in a dose-dependent manner. The EA fraction also inhibited histamine release from rat peritoneal mast cells stimulated by compound 48/80, which promotes histamine release. Furthermore, EA fraction had inhibitory effects on scratching behavior induced by compound 48/80 in Balb/c mice. These results suggest that the EA fraction from D. lotus leaves has potential as ameliorative agent against oxidative stress and pruritus-related disease.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.11
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• pp.1727-1735
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• 2013

This study is carried out to investigate the analysis of nutrition and antioxidants of soybean Chungkukjang powder (SCP), Yak-Kong Chungkukjang powder (YCP) and Yak-Kong Chungkukjang powder added black foods (YCBP) for the management of Alzheimer's disease. The water content of YCBP was higher than that of SCP and YCP. The soluble and crude protein contents of YCP were the highest among three Chungkukjang powders. In SCP, YCP and YCBP, the ratios of unsaturated and saturated fatty acids were 5.17, 5.76, and 5.78, respectively. The mineral content of SCP was higher than that of YCP and YCBP. Antioxidants analysis showed that the content of diadzein was the highest in YCP and genistein, and anthocyanin contents were higher than the others in YCBP. In conclusion, YCP and YCBP had higher contents than SCP in soluble and crude proteins, and unsaturated fatty acids, which are needed for composition and function of the brain tissue. Also, it was found that the contents of diadzein, genistein and anthocyanin with outstanding antioxidative ability were high. Thus, this study suggests that Chungkukjang powder, which is made with Yak-Kong, black sesame, black rice and sea tangle, can be utilized for in vivo experiment for the control of oxidative stress, reported as cause and therapy for Alzheimer's Disease.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.101-115
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• 2016

We carried out laboratory material tests on two cements (KS-1 ordinary Portland and Class G) with changing W/S (Water/Solid) and the content of fly ash in order to evaluate their physical and mechanical properties. The specimens of KS-1 ordinary Portland cement were prepared with varying W/S (Solid=cement) in weight, while those of Class G cement were prepared with changing the content of fly ash in volume but maintaining W/S (Solid=cement+fly ash). The results of the material tests show that as the W/S in KS-1 ordinary Portland cement and the content of fly ash in Class G cement increase, the properties (density, sonic wave velocity, elastic constants, compressive and tensile strengths, thermal conductivity) decrease, but porosity and specific heat increase. In addition, an increase in confining pressure and in the content of fly ash leads to plastic failure behavior of the cements. The laboratory data were then used in a stability analysis of cement sheath for which an analytical solution for computing the stress distribution induced around a cased, cemented well was employed. The analysis was carried out with varying the injection well parameters such as thickness of casing and cement, injection pressure, dip and dip direction of injection well, and depth of injection well. The analysis results show that cement sheath is stable in the cases of relatively lower injection pressures and inclined and horizontal wells. However, in the other cases, it is damaged by mainly tensile failure.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.117-128
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• 2016

Chemical reaction tests were performed to assess the properties of hardened specimens of cement pastes (KS-1 Portland and Class G) exposed to supercritical CO₂ for 1, 10, and 100 days. After exposure, the samples' measured permeability and strength were compared with values measured for pristine samples. The pristine cements had permeabilities of 0.009~0.025 mD, which increased by one order of magnitude after 100 days of exposure (to 0.11~0.29 mD). The enhancement of permeability is attributed to the stress release experienced by the samples after removal from the pressure vessel after exposure. Despite its enhancement, the measured permeability mostly remained lower than the API (American Petroleum Institute) recommended maximum value of 0.2 mD. The degradation of the cement samples due to exposure to supercritical CO₂ led to a layer of altered material advancing inwards from the sample edges. The Vickers hardness in the altered zone was much higher than that in the unaltered zone, possibly owing to the increase in density and the decrease in porosity due to the carbonation that occurred in the altered zone. Hardness close to the edge within the altered zone was found to have decreased significantly, which is attributed to the conversion of C-S-H into less-strong amorphous silica.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.93-99
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• 2020

A colorimetric paper sensor was used to detect volatile nitrogen-containing compounds emitted from spoiled salmon filets to determine their freshness. The sensing mechanism was based on acid-base reactions between acidic pH-indicating dyes and basic volatile ammonia and amines. A sensing layer was simply fabricated by drop-casting a dye solution of bromocresol green (BCG) on a polyvinylidene fluoride substrate, and its color-change response was enhanced by optimizing the amounts of additive chemicals, such as polyethylene glycol, p-toluene sulfonic acid, and graphene oxide in the dye solution. To avoid the adverse effects of water vapor, both faces of the sensing layer were enclosed by using a polyethylene terephthalate film and a gas-permeable microporous polytetrafluoroethylene sheet, respectively. When exposed to basic gas analytes, the paper-like sensor distinctly exhibited a color change from initially yellow, then to green, and finally to blue due to the deprotonation of BCG via the Brønsted acid-base reaction. The use of ammonia analyte as a test gas confirmed that the sensing performance of the optimized sensor was reversible and excellent (detection time of < 15 min, sensitive naked-eye detection at 0.25 ppm, good selectivity to common volatile organic gases, and good stability against thermal stress). Finally, the coloration intensity of the sensor was quantified as a function of the storage time of the salmon filet at 28℃ to evaluate its usefulness in monitoring of the food freshness with the measurement of the total viable count (TVC) of microorganisms in the food. The TVC value increased from 3.2 × 10⁵ to 3.1 × 10⁹ cfu/g in 28 h and then became stable, whereas the sensor response abruptly changed in the first 8 h and slightly increased thereafter. This result suggests that the colorimetric response could be used as an indicator for evaluating the degree of decay of salmon induced by microorganisms.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.3
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• pp.248-253
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• 1990

Germination and seedling growth of chinese milkyetch (Astragalus sinicus L. Line A) seeds were measured at four temperatures (15. 25. 30, and 35$^{\circ}C$), three polyethylene glycol (PEG) 10.000 (MW) solutions (0, 20 and 25 g/100$m\ell$ H$_2$O), and five sulfuric acid treatments (conc, H$_2$SO$_4$: Seeds/weight base: 0, 1:1 10min.. 1:1 20min.. 1:1.5 10min. and 1:1.5 20min, immersion), Adjustments of PEG 10.000 solutions were based on water potentials of 0.0, -0,5 and -0.8 ㎫ at room temperature. Observations were taken at 7 days for each treatment combinations. Germination percent of chinese mikvetch seeds was the highest at 15$^{\circ}C$ and seeding length was the longest at 25$^{\circ}C$. Both germination percent and seedling length were rapidly decreased as PEG concentration increased from 0 to 25g/100$m\ell$ H$_2$O. The highest germination percent was found at PEG 20 and 25 of 15$^{\circ}C$ among those of four temperatures, Sulfuric acid treatments showed little effect on germination percent and seedling length compared to untreated control, However. in the case of PEG 0, greater germination perccent was obtained at the treatment of 1:1.5 for 10 minutes immersion, The result of this study-indicated that germination of chinese milkvetch seeds was affected mostly by moisture stress conditions.

• Journal of Life Science
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• v.9 no.2
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• pp.169-175
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• 1999

Salmonella typhimurium can encounter a wide variety of environments during its life cycle. In nature, S. typhimurium can experience and survive dramatic acid stresses that occur in diverse ecological niches ranging from pond water to phagolysosomes. These survival mechanism is aquired by the Acid Tolerance Response(ATR) in Salmonella. The ATR of S. typhimurium is a complex inducible phenomenon in which exposures to slight or moderate low pH will produce a stress response capable of protecting the organism against more severe acid challenges. ATR in Salmonella has two different systems that are called RpoS dependent and independent. We found that ATR in anaerobic was showed RpoS independent because rpoS$\Omega$AP had ATR as S. typhimurium UK1. Using the P22 MudJ(Km, lacZ) operon fusion technique and a lethal selection procedure combining low pH(pH4.5) and sodium acetate(10mM, pH4.5), we isolated LF487 aatA::MudJ which showed acid sensitive in anaerobic condition. aatA locus was determined at 12 min on Salmonella Genetic Map. The survival rate of aatA mutant was showed significantly diminished at pH4.3 than virulent wild type Salmonella in anaerobic condition(5% $CO_2$, 5% H$_2$, 90% $N_2$). Therefore isolated gene was confirmed important gene for anaerobic ATR system.

• Journal of Life Science
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• v.9 no.2
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• pp.231-240
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• 1999

Regular exercise is effective in preventing coronary disease such as angina pectoris and infarction, inside it can lower the blood pressure and aids in weight control and release of stress. Risk factors of arteriosclerosis is hypertension, hyperlipidemia, diabetes, obesity, physical inactivity and excessive smoking. Arteriosclerosis begins at young age worsens with age, particulary in male. For people with risk factors of arteriosclerosis, it is important to prevent arteriosclerosis-related disease with dietary, living pattern and exercise prescription. Dietary fibers promote exercise of the digestive tract and shortens the time food remains inside the digestive tract. It can prevent obesity, hyperlipidemia, arteriosclerosis and colin cancer by blocking the absorption of cholesterol. Various vegetables and sea foods are lichen unsaturated fats and prevent the absorption of cholesterol inside the digestive tract. Essential fatty acids and unsaturated fats which are contained in vegetable oils, promotes metabolism while preventing absorption. In fruits, pectin water-soluble fiber, is present and lowers the level of cholesterol. By consuming foods that low in cholesterol and saturated fats, and rich in unsaturated fats, aliomentotherapy alone can reduce the plasma cholesterol by 10~l5$\%$. For ideal exercise, it should be aerobic with intensity of 60~80$\%$ HRmax, duration of 15~60min/day. The frequancy of 3~6/week is desirable the better exercise prescription is endurance aerobic exercise. To get more effect exercise, exercise consistency is very important.