• Journal of Periodontal and Implant Science
• /
• 제37권3호
• /
• pp.613-624
• /
• 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.

• 한국유체기계학회 논문집
• /
• 제2권3호
• /
• pp.45-51
• /
• 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.

• 보건교육건강증진학회지
• /
• 제26권2호
• /
• pp.25-33
• /
• 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.

• 한국정보통신학회논문지
• /
• 제10권3호
• /
• pp.479-485
• /
• 2006

이중게이트 MOSFET는 스케일링 이론을 확장하고 단채널효과를 제어 할 수 있는 소자로서 각광을 받고 있다. 단 채널효과를 제어하기 위하여 저도핑 초박막 채널폭을 가진 이중게이트 MOSFET의 경우, 20nm이하까지 스케일링이 가능한 것으로 알려지고 있다. 이 논문에서 는 20m이하까지 스켈링된 이중게이트 MOSFET소자에 대한 분석학석 전송모델을 제시하고자 한다. 이 모델을 이용하여 서브문턱스윙(Subthreshold swing), 문턱전압변화(Threshold voltage rolloff) 드레인유기장벽저하(Drain induced barrier lowering)와 같은 단채널효과를 분석하고자 한다. 제안된 모델은 열방출 및 터널링에 의한 전송효과를 포함하고 있으며 이차원 포아슨방정식의 근사해를 이용하여 포텐셜 분포를 구하였다. 또한 터널링 효과는 Wentzel-Kramers-Brillouin 근사를 이 용하였다. 이 모델을 사용하여 초박막 게이트산화막 및 채널폭을 가진 5-20nm 채널길이의 이중게이트 MOSFET에 대한 서브문턱영역의 전송특성을 해석하였다. 또한 이 모델의 결과값을 이차원 수치해석학적 모델값과 비교하였으며 게이트길이, 채널두께 및 게이트산화막 두께에 대한 관계를 구하기 위하여 사용하였다.

• Journal of Periodontal and Implant Science
• /
• 제48권1호
• /
• pp.47-59
• /
• 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.

• 한국치위생학회지
• /
• 제22권5호
• /
• pp.365-374
• /
• 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
• /
• 제47권1호
• /
• pp.1-13
• /
• 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
• /
• 제32권3호
• /
• pp.565-576
• /
• 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.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2002년도 춘계 학술발표회 논문집
• /
• pp.3-11
• /
• 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.

• 대한화학회지
• /
• 제20권3호
• /
• pp.198-205
• /
• 1976

Parr의 Integral Hellmann-Feynman이론을 비대각꼴에 까지 일반화하여 의의를 갖도록 하였으며 그 특징을 논하였다. 그리하여 이 비대각꼴을 결정장론에 미치는 배치작용의 효과를 검토하는데 적용함으로서, 모든 차의 섭동 에너지를 하나의 묶음으로서 도입하였다. 그 결과 ${\Gamma}$, S 및 m로 특징지워지는 상태들에게, 파라미터화 할 수 있는 공통적인 동경적분이 존재하지 않음을 밝혔다. 그러나 만일 각 성분에 변형이 없고 동경성분에게 동등한 변형만이 있는 여기된 배치들의 작용만을 허락한다면, 이는 고전적인 결정장론에서 결정장 파라메터 10 Dq와 Condon-Slater 적분 $F^n$의 척도를 변경시키는 결과를 초래함을 알게 되었다.