• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.1
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• pp.39-45
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• 2018

Purpose: The purpose of this study was to evaluate the clinical effects of erythritol powder air polishing device (EPAP) in addition to scaling and root planing (SRP) in non-surgical periodontal treatment in moderate chronic periodontitis patients. Materials and Methods: Clinical evaluation was performed at 21 sites treated with SRP (control) and 21 sites treated with the addition of SRP+EPAP (test). All examinations were performed before treatment, 1 month after treatment, and 3 months after treatment. Depth of the periodontal pocket, gingival recession, clinical attachment level, plaque index, and bleeding of probing were measured as clinical parameters. Results: In both test and control groups, there was a significant decrease in the depth of the periodontal pocket, plaque index, bleeding of probing, increased gingival recession, and gain of clinical attachment level at 1 month and 3 months after treatment. However, there was no significant clinical difference between the test group and the control group. Clinical result was improved after 1 month compared to the baseline; in contrast, results at 3 months after treatment were worse than at 1 month after treatment. Conclusion: In this study, we cannot suggest that SRP + EPAP is clinically more effective than SRP alone as non-surgical periodontal treatments. Periodic periodontal therapy, at intervals of at least every three months, is important for sustaining effects of this treatment.

• Journal of Periodontal and Implant Science
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• v.37 no.3
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• pp.613-624
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• 2007

Full-mouth disinfection (Fdis) completes the entire scaling and root planing (SRP) in one stage within 24 hours for the prevention of microbial recolonization from untreated sites and ecological niches. The aim of this study is to compare the clinical short-term effects of modified Fdis with those of the conventional SRP in the therapy of moderate and severe chronic periodontitis. Modified Fdis group (5 patients) received the entire SRP within 24 hours using chlorhexidine solution (0.1%) and conventional SRP group (5 patients) received SRP per quadrant at one-week intervals. Clinical parameters were measured at baseline, one month and three months after both therapies. The results of this case report were as follows: 1. There were considerable decreases in sulcus bleeding index and plaque index one month after Fdis. 2. The mean probing depth of single-rooted teeth decreased more in Fdis group than conventional SRP group after therapy and, that of multi-rooted teeth decreased similarly in both groups. 3. The mean probing depth decreased 1.77mm in case of initial probing depth of 4-6mm and it decreased 4.13mm in case of initial probing depth of ${\geq}$ 7mm three months after Felis. 4. There were the smaller increases in gingival recession together with the larger gains in attachment in Fdis group than conventional SRP group after three months. Within the limitations of this study, one could conclude that Fdis has beneficial clinical effects in the treatment of moderate and severe chronic periodontitis and further research would be helpful including more subjects during a longer period to confirm the beneficial long-term effects of Fdis.

• The KSFM Journal of Fluid Machinery
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• v.2 no.3 s.4
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• pp.45-51
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• 1999

Centrifugal fans are widely used and the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the casing. However, only a few researches have been carried out on predicting the noise due to the difficulty in obtaining detailed information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan and to calculate the effects of rotating velocity, flow rate, cut-off distance and the number of blades and its effects on the noise of the fan. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated with the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. The cut-off distance is the most important factor effecting the noise generation. Acoustic pressure is proportional to 2.8, which shows the same scaling index as the experimental result. In this paper, the cut-off distance is found to be the dominant parameter offecting the acoustic pressure.

• Korean Journal of Health Education and Promotion
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• v.26 no.2
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• pp.25-33
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• 2009

Objectives: Smoking is related to periodontal disease and periodontal therapy. So the aim of this study was to investigate the effects of professional tooth cleaning and plaque control instruction (PT & PCI) for smoking behavior. Methods: A total of 151 adults were investigated using the O'Leary Plaque Index (PI), $L\ddot{o}e$ & Silness gingival index (GI) and the number of sextants possessing periodontal pocket (SPP). And adults were given a through dental scaling and Watanabe method for dental plaque control. Follow up examination were conducted after 3 months and compared the pre and post- status. The collected data were analyzed with t-test, paired t-test and one-way analysis of variance. Results: Regardless of smoking behavior, improving effects were identified after PT & PCI on PI, GI and SPP in the whole population. However, the effects of GI improvement were significant in the smoking group alone; those of PI improvement were most significant in the non-smoking group; and those of SPP improvement were more significant in non-smoking and pre-smoking groups than in the smoking group. The shorter period of smoking and the smaller amount of smoking, the greater effects of PT & PCI by smoking-related characteristics. Conclusion: Smoking cessation instruction should necessarily be included in oral health education in that smoking is an important factor to consider in prevention of periodontal diseases and periodontal therapies.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.479-485
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• 2006

The double gate(DG) MOSFET is a promising candidate to further extend the CMOS scaling and provide better control of short channel effect(SCE). DGMOSFETs, having ultra thin undoped Si channel for SCEs control, ale being validated for sub-20nm scaling. A novel analytical transport model for the subthreshold mode of DGMOSFETs is proposed in this paper. The model enables analysis of short channel effect such as the subthreshold swing(SS), the threshold voltage roil-off$({\Delta}V_{th})$ and the drain induced barrier lowering(DIBL). The proposed model includes the effects of thermionic emission and quantum tunneling of carriers through the source-drain barrier. An approximative solution of the 2D Poisson equation is used for the distribution of electric potential, and Wentzel-Kramers-Brillouin approximation is used for the tunneling probability. The new model is used to investigate the subthreshold characteristics of a double gate MOSFET having the gate length in the nanometer range $(5-20{\sim}nm)$ with ultra thin gate oxide and channel thickness. The model is verified by comparing the subthreshold swing and the threshold voltage roll-off with 2D numerical simulations. The proposed model is used to design contours for gate length, channel thickness, and gate oxide thickness.

• Journal of Periodontal and Implant Science
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• v.48 no.1
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• pp.47-59
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• 2018

Purpose: To evaluate the clinical and microbiological effects of the local use of egg yolk immunoglobulin against Porphyromonas gingivalis (anti-P.g. IgY) as an adjunct to scaling and root planing (SRP) in the treatment of moderate to severe chronic periodontitis. Methods: This was a randomized, placebo-controlled, double-blind trial involving 60 systematically healthy patients with moderate to severe chronic periodontitis. Subjects (n=20/group) were randomly assigned to receive SRP combined with subgingival irrigation of anti-P.g. IgY and anti-P.g. IgY mouthwash, subgingival irrigation of 0.2% chlorhexidine and 0.2% chlorhexidine mouthwash, or subgingival irrigation of placebo and placebo mouthwash for 4 weeks. Probing pocket depth, clinical attachment level, bleeding on probing, and the plaque index were evaluated at baseline and at 4 weeks. Subgingival plaque, gingival crevicular fluid, and saliva were simultaneously collected for microbiological analysis. Results: Our results showed that anti-P.g. IgY mouthwash was as effective as chlorhexidine at improving clinical parameters over a 4-week period. All the groups showed a significant reduction in levels of P.g. at 4 weeks. No significant difference was observed in the test group when compared to placebo regarding the reduction in the levels of P.g. Anti-P.g. IgY significantly suppressed the numbers of red complex bacteria (RCB) in subgingival plaque and saliva in comparison with placebo. No adverse effects were reported in any of the subjects. Conclusions: Within the limitations of the study, the present investigation showed that passive immunization with anti-P.g. IgY may prove to be effective in the treatment of chronic periodontitis due to its ability to improve clinical parameters and to reduce RCB. No significant differences were found between the anti-P.g. IgY and placebo groups in the reduction of P.g.

• Journal of Korean society of Dental Hygiene
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• v.22 no.5
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• pp.365-374
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• 2022

Objectives: The purpose of this study was to determine the effects of dental hygienists' grit, job satisfaction, and job commitment on dental hygiene job performance and the mediating effects of job satisfaction and job commitment on the relationship between grit. Methods: From May 25 to June 13, 2022, the researcher collected and analyzed data from 213 dental hygienists working at dental hospitals and clinics. For the data analysis, SPSS Statistics 21.0 was applied to conduct a t-test, one-way ANOVA, Pearson's correlation analysis, and hierarchical regression analysis. Results: Grit was in charge of preventive work (scaling) (3.38±0.56, p<0.05), and the lower the stress (3.39±0.57, p<0.05), the higher the grit. Dental hygiene job performance was higher when they worked in Gwangju, Jeolla-do (3.88±0.50, p<0.01), and dental clinics (3.85±0.53, p<0.01). Job satisfaction (3.45±0.49, p<0.05) and job commitment (3.28±0.56, p<0.05) were high, as they had at least a bachelor's degree. Less job stress was associated with higher job satisfaction (3.71±0.42, p<0.001) and job commitment (3.52±0.65, p<0.001). Job satisfaction and commitment had partial mediating effects on the relationship between dental hygienists' grit and job performance. Conclusions: It is necessary to develop a program that helps improve grit in dental hygienists to strengthen their psychological resources, job satisfaction, and job commitment.

• Journal of Ecology and Environment
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• v.47 no.1
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• pp.1-13
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• 2023

Background: The positive effects of Arctic plants on the soil environment and plant-species co-occurrence patterns are known to be particularly important in physically harsh environments. Although three dominant plants (Cassiope tetragona, Dryas octopetala, and Silene acaulis) are abundant in the Arctic ecosystem at Ny-Ålesund, Svalbard, few studies have examined their occurrence patterns with other species and their buffering effect on soil-temperature and soil-moisture fluctuation. To quantify the plant-species co-occurrence patterns and their positive effects on soil environments, I surveyed the vegetation cover, analyzed the soil-chemical properties (total carbon, total nitrogen, pH, and soil organic matter) from 101 open plots, and measured the daily soil-temperature and soil-moisture content under three dominant plant patches and bare soil. Results: The Cassiope tetragona and Dryas octopetala communities increased the soil-temperature stability; however, the three dominant plant communities did not significantly affect the soil-moisture stability. Non-metric multidimensional scaling separated the sampling sites into three groups based on the different vegetation compositions. The three dominant plants occurred randomly with other species; however, the vegetation composition of two positive co-occurring species pairs (Oxyria digyna-Cerastium acrticum and Luzula confusa-Salix polaris) was examined. The plant species richness did not significantly differ in the three plant communities. Conclusions: The three plant communities showed distinctive vegetation compositions; however, the three dominant plants were randomly and widely distributed throughout the study sites. Although the facilitative effects of the three Arctic plants on increases in the soil-moisture fluctuation and richness were not quantified, this research enables a deeper understanding of plant co-occurrence patterns in Arctic ecosystems and thereby contributes to predicting the shift in vegetation composition and coexistence in response to climate warming. This research highlights the need to better understand plant-plant interactions within tundra communities.

• Journal of Periodontal and Implant Science
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• v.32 no.3
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• pp.565-576
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• 2002

The ultimate goal of periodontal therapy is the regeneration of periodontal tissue which has been lost due to destructive periodontal disease. To achieve periodontal regeneration, various kinds of methods have been investigated and developed, including guided tissue regeneration and bone graft. Bone graft can be catagorized into autografts, allografts, xenografts, bone substitutes. And materials of all types have different biological activity and the capacity for periodontal regeneration, but ideal graft material has not been developed that fits all the requirement of ideal bone graft material. Intensive research is underway to identity, purify, synthesize a variety biologic modulators that may enhance wound healing and regeneration of lost tissues in periodontal therapy. The present study evaluates the effects of ABM/P-15 on the periodontal regeneration in intrabony defects of human. We used thirty four 2-wall or 3-wall osseous defects in premolars and molars of chronic peridontitis patient that have more than 5mm pockets and more than 3mm in intrabony defect. 12 negative control group underwent flap procedure only, 11 positive control group received DFDBA graft with flap procedure, and 11 experimental group received ABM/P-15 graft with flap procedure. The changes of probing pocket depth, loss of attachment and bone probing depth following 6months after treatment revealed the following results: 1. The changes of probing pocket depth showed a statistically significant decrease between after scaling and 6months after treatment in negative control(2.0${\pm}$0.9mm), positive control(3.0${\pm}$0.9mm), and experimental group (3.4${\pm}$1.5mm) (P<0.01). Significantly more reduction was seen in experimental group compared to negative control group (P<0.05). 2. The changes of loss of attachment showed a statistically significant decrease between after scaling and 6months after treatment in positive control(2.0${\pm}$0.6mm), and experimental group (2.2${\pm}$l.0mm) except negative control group(0.1${\pm}$0.7mm) (P<0.01). Significantly more reduction was seen in both experimental and positive control group compared to negative control group(P<0.05). 3. The changes of bone probing depth showed a statistically significant decrease between after scaling and 6months after treatment in positive control(2.7${\pm}$l.0mm), and experimental group (3.4${\pm}$1.3mm) except negative control(0.l${\pm}$0.9mm) (9<0.01). Significantly more reduction was seen in both experimental and positive control group compared to negative control group (P<0.05). The results suggest that the use of ABM/P-15 in the treatment of periodontal intrabony defects can reduce loss of attachment and bone probing depth more than flap operation only. It suggests that ABM/P-15 may be an effective bone graft material for the regeneration of periodontal tissue in intrabony defects.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.3-11
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• 2002

Source parameters for forty nine recent earthquakes occurred in and around Korean Peninsula are determined and the relations among them are studied. The corner frequency and seismic moment are estimated from three different methods. The spectral fitting of the source displacement spectrum with the $\omega$-square source model of Brune(1970) and Snoke(1987)'s method are applied to all events and empirical Green's function method for two events are adopted. The source parameters determined in this study show different values depending on the adopted method and on the stations of which seismograms are recorded. It is interpreted that the disagreements principally originate from insufficient consideration of source radiation pattern and attenuation and amplification according to path direction. The corner frequencies and seismic moments are averaged to exclude the directional effects and other source parameters are estimated from the mean corner frequency and seismic moment. The static stress drops estimated in this study tend to be independent of seismic moment or magnitude for events above a certain size. For earthquakes with the size less than about 3.0$\times$10$^{21}$dyne-cm(nearly same as M$_{L}$=3.7), the stress drop tends to decrease with the decreasing moment. This fact suggests a breakdown of scaling law of source parameters below the threshold magnitude. The moment magnitudes calculated from source parameters appear to be slightly larger than the Richter's local magnitudes in the range above M$_{L}$=3.5.3.5.