• 한국치위생학회지
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• 제10권5호
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• pp.947-953
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• 2010

Objectives : The purpose of this investigation was to evaluate the remineralization and acid resistance in fluoride varnish by Micro-computed tomography (micro CT). Methods : Specimens of bovine teeth enamel were embedded in resin, polished and randomly divided into 3 groups (a control group, a NaF solution group, a fluoride varnish group). Each group has 3 specimens that was standardized according to Vickers hardness number (VHN). Specimens were immersed in demineralization solution for 72 hours. The control group had no treatment, the NaF solution group was treated by a 5% NaF solution for 4 minutes, and the fluoride varnish group was treated by a fluoride varnish for one hour. All specimens were subjected to a chemical pH cycling method for 14 days. After a chemical pH cycling method, the density were measured using micro CT. Then, specimens were immersed in each demineralization solution for 72 hours. After demineralization processed, the density were measured using micro CT. Results : 1. The density was significantly higher in the fluoride varnish and 5% NaF solution group than that of the control group after 14 days cycling (p<0.05). And the density value of the fluoride varnish group was higher than that of the 5% NaF solution, with no significant difference. 2. The differences of density after acid resistance treatment were statistically significant among 3 groups(p<0.05). Conclusions : It is suggested that fluoride varnish showed the remineralizing effect and acid resistance effect on the enamel, and micro CT could be used to evaluate the change of enamel lesion.

• 한국한의학연구원논문집
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• 제16권1호
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• pp.149-155
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• 2010

Objective : Ssangwha-tang is a traditional medicine formula widely prescribed for a decrease of fatigue after an illness in Korea. The aim of this study is to investigate the effect of Ssangwha-tang fermented by Lactobacillus fermentum (SF) on osteoclast differentiation in vitro and on bone metabolism of an ovariectomized rat in vivo. Methods : Tartrate-resistant acid phosphatase activity and staining were applied to evaluate the formation of osteoclasts. Ovariectomized rats were orally administrated with SF (30 ml/kg/day) for 12 weeks. Serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, triglyceride, phosphate, calcium levels were determined. Effect of SF on bone loss were studied by histological analysis and the measurement of bone mineral density. Results : SF significantly inhibited tartrate-resistant acid phosphatase activity and formation of osteoclasts in RAW264.7 cells stimulated by receptor activator for nuclear factor ${\kappa}B$ (NF-${\kappa}B$) ligand (RANKL). In addition, SF significantly decreased the level of triglyceride and increased the level of low-density lipoprotein. Moreover, the decrease of trabeculae of the femur was partially prevented in ovariectomized rats administrated with SF. Conclusions : SF treatment could prevent ovariectomy induced bone loss and its effects could be medicated by the inhibition of osteoclastogenesis.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.179-188
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• 2003

The spray characteristics of dual orifice injector were investigated under two different fuels through measurement of SMD, number density and volume flux by using PDPA system. In this experiment, we found out that the droplet size and spray structure are strongly depend on fuel density and viscosity.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2015년도 임시총회 및 하계학술연구발표회
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• pp.78-79
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• 2015

We investigate the switching current for various cell diameters and DM interaction. We find that the current density for switching can depend strongly on the cell size when the switching is governed by the domain wall motion. Moreover the switching current density is also strongly influenced by DM interaction. In the presentation, we will discuss the effect of domain wall formation and more various DMI constant on the switching current desity in detail.

• 천문학회지
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• 제17권2호
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• pp.115-125
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• 1984

Effect of magnetic field on the thermal instability is studied in the radiatively cooling region behind an interstellar shock of moderate propagation velocity (${\sim}10\;km/sec$). It is shown that the presence of interstellar magnetic field of a few micro gauss is very effective in preventing the thermal instability from building-up density concentration. In the absence of magnetic field, the shock-induced thermal instability amplifies preshock density inhomogeneity by more than an order of magnitude. However, in the presence of magnetic field, the amplified density contrast is shown to be only a factor 2.

• 한국통계학회:학술대회논문집
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• 한국통계학회 2003년도 춘계 학술발표회 논문집
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• pp.69-74
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• 2003

The estimation of pest density is a prime concern of Integrated Pest Management (IPM) because the success of artificial intervention such as spraying pestcides or natural enemies depends on pest density. Also, the spatial pattern of pest population within plants or plots has been studies in various ways. In this study, we applied generalized linear mixed model to Tetranychus urticae Koch , two-spotted spider mite count in glasshouse grown roses. For this analysis, the subject-specific as well as pupulation-averaged approaches are used.

• 한국세라믹학회지
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• 제37권5호
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• pp.511-515
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• 2000

The effect of Ba2+ ion dissolution with different pH and amount of PAA on microstructural changes of green and sintered bodies and its electrical properties was studied in aqueous nano-size BaTiO3 slurry system. The dissolution of Ba2+ was least at strong base, pH 10.8 and by addition of amount of 0.15 wt% PAA. The green body with the lowest of dissolution of Ba2+ at pH 10.8 and 0.15 wt% PAA had minimum values of average pore size, 40nm and shown high increase of sintered density. The compact sintered at 125$0^{\circ}C$ for 2 hr with highest Ba2+ dissolution had low density and dielectric constant due to abnormal grian growth. However, the sintered body with the lowest Ba2+ dissolution had high sintered density and then shown high dielectric constant.

• 한국세라믹학회지
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• 제53권3호
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• pp.312-316
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• 2016

The energetics of defects in the presence of domain walls in $LiNbO_3$ are characterized using density-functional theory calculations. Domain walls show stronger interactions with antisite defects than with interstitial defects or vacancies. As a result, antisite defects act as a strong pinning center for the domain wall in $LiNbO_3$. Analysis of migration behavior of the antisite defects across the domain wall shows that the migration barrier of the antisite defects is significantly high, such that the migration of antisite defects across the domain wall is energetically not preferable. However, further study on excess electrons shows that the migration barrier of antisite defects can be lowered by changing the charge states of the antisite defects. So, excess electrons can enhance the migration of antisite defects and thus facilitate domain wall movement by weakening the pinning effect.

• Transactions on Electrical and Electronic Materials
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• 제13권2호
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• pp.89-92
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• 2012

The effect of organic impurities on the electrical properties of a neat epoxy resin was studied. 0.05, 0.5 and 1.0 phr of iso-propyl alcohol (IPA) and methylene chloride (MC) mixture (50/50 wt%) were used as impurities. The current density, volume resistance and impedance characteristics of the epoxy/IPA/MC systems were measured with a high voltage source meter and broadband dielectric spectroscopy. Glass transition temperature (Tg) was measured by a differential scanning calorimetry (DSC) and it was found that Tg decreased slightly with increasing IPA/MC content. It was also found that Tg values of the epoxy systems with various IPA/MC contents were closely related to the current density, volume resistance and impedance characteristics.

• 한국환경과학회지
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• 제15권12호
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• pp.1177-1183
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• 2006

This study was carried out to evaluate effect of sludge characteristics (pH, SVI, anaerobic storage, wet density and growth phase) on the sedimentation of bulking sludge of paper manufacturing plant. The results showed that mix hulking sludge with sewage sludge (10-60%) caused the decrease of SVI, the settled sludge concentration was increased. Increase of anaerobic storage time (0 to 8 day) was increased SVI, sedimentation performance was deteriorated. The sedimentation was improved by addition of loess (0.2-5.0 g/L), because wet density of sludge was increased and SVI was decreased. At an exponential phase, the ratio of sedimented/growthed sludge concentration was decreased, the ratio was increased after stationary phase.