• Journal of the Korean Society of Groundwater Environment
• /
• v.5 no.4
• /
• pp.215-222
• /
• 1998

The objective of this study was to investigate the effects of physico-chemical environmental factors on the changes of bacterial population from two sites used for drinking water and eight sites polluted with various pollutant in Seoul city. In all the stations except for two sites used for drinking water, the concentrations of nitrate- nitrogen and ammonia were in excess of the criteria of groundwater quality by the result of analysis of 40 variations including physicochemical environmental factors, heavy metals, and bacterial populations. The numbers of total bacteria, heterotrophic bacteria and functional groups of bacteria were ranged from 5.1 to 41.4${\times}$10$\^$5/cells/ml and from 0.01 to 29.6${\times}$10$^4$cfu/ml, respectively. The activities of extracellular enzymes showed the ranges of 0.005∼11.3${\mu}$M/l/hr and its order to lipase, phophatase, ${\beta}$-glucosidase, cellulase, chitinase, amylase. The results of correspondence and multidimensional scaling analysis between bacterial populations and its physico-chemical environmental factors were explained the effects of physico-chemical environmental factors according to site characters and separated four group, which is accord with potential pollutants at wells.

• Journal of Periodontal and Implant Science
• /
• v.44 no.6
• /
• pp.280-287
• /
• 2014

Purpose: The purpose of this randomized single-blind controlled trial was to elucidate the clinical and antimicrobial effects of daily phototherapy (PT) as an adjunct to scaling and root planing (SRP) in patients with chronic periodontitis. Methods: The study was conducted from December 2013 to May 2014 at Ewha Womans University Mokdong Hospital, Seoul, Korea. Forty-one patients with mild to moderate chronic periodontitis were randomly divided into two therapeutic groups in a 1:1 ratio: SRP+PT and SRP (control) groups. All participants underwent full-mouth SRP. PT was performed thrice a day for a month by using electric toothbrushes with embedded light-emitting diodes. Plaque index, gingival index, probing pocket depth (PPD), clinical attachment level (CAL), and bleeding on probing were assessed before (baseline) and four weeks after (follow-up) the treatment. Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Prevotella intermedia, Fusobacterium nucleatum, Parvimonas micra, Campylobacter rectus, Eikenella corrodens, Streptococcus mutans, and Streptococcus sobrinus levels were detected by a real-time polymerase chain reaction at the same points in time. Results: The clinical parameters improved in both the groups. At the follow-up assessment, PPD was significantly decreased in the SRP+PT group (P=0.00). Further, PPD and CAL showed significantly greater changes in the SRP+PT group than in the SRP group (PPD, P=0.03; CAL, P=0.04). P. gingivalis and T. forsythia levels decreased in this group, but no significant intergroup differences were noted. Conclusions: Adjunctive PT seems to have clinical benefits, but evidence of its antimicrobial effects is not sufficient. Long-term studies are necessary to develop the most effective PT protocol and compare the effectiveness of PT with and without exogenous photosensitizers.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.05a
• /
• pp.683-685
• /
• 2012

This paper have presented the analysis of the change for threshold voltage and drain induced barrier lowering among short channel effects occurred in subthreshold region for double gate(DG) MOSFET with two gates to be next-generation devices, based on scaling theory. To obtain the analytical solution of Poisson's equation, Gaussian function been used as carrier distribution to analyze closely for experimental results, and the threshold characteristics have been analyzed for device parameters such as channel thickness and doping concentration and projected range and standard projected deviation of Gaussian function. Since this potential model has been verified in the previous papers, we have used this model to analyze the threshold chatacteristics. As a result to apply scaling theory, we know the threshold voltage and drain induced barrier lowering is changed, and the deviation rate is changed for device parameters for DGMOSFET.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.05a
• /
• pp.283-290
• /
• 2007

Recently, plastic products in air-intake parts of automotive engines have become very popular due to advantages that include reduced weight, constricted cost, and lower intake air temperature. However, flow-induced noise in air-intake parts becomes a more serious problem for plastic intake-manifolds than for conventional aluminum-made manifolds. This is due to the fact that plastic manifolds transmit more noise owing to their lower material density. Internal aerodynamic noise from an Idle Speed control Actuator (ISA) is qualitatively analyzed by using a scaling law, which is expressed with some flow parameters such as pressure drop, maximum flow velocity, and turbulence kinetic energy. First, basic flow characteristics through ISA passage are identified with the flow predictions obtained by applying Computational Fluid Dynamics techniques. Then, the effects on ISA passage noise of each design factors including the duct turning shape and vane geometries are assessed. Based on these results, the preliminary low noise design for the ISA passage are proposed. The current method for the prediction of internal aerodynamic noise consists of the steady CFD and the scaling laws for the noise prediction. This combination is most cost-effective, compared with other methods, and therefore is believed to be suited for the preliminary design tool in the industrial field.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.17 no.8
• /
• pp.683-692
• /
• 2007

Recently, plastic products in air-intake parts of automotive engines have become very popular due to advantages that include reduced weight, constricted cost, and lower intake air temperature. However, flow-induced noise in air-intake parts becomes a more serious problem for plastic intake-manifolds than for conventional aluminum-made manifolds. This is due to the fact that plastic manifolds transmit more noise owing to their lower material density. Internal aerodynamic noise from an idle speed control actuator(ISA) is qualitatively analyzed by using a scaling law, which is expressed with some flow parameters such as pressure drop, maximum flow velocity, and turbulence kinetic energy. First, basic flow characteristics through ISA passage are identified with the flow predictions obtained by applying computational fluid dynamics techniques. Then, the effects on ISA passage noise of each design factors including the duct turning shape and vane geometries are assessed. Based on these results, the preliminary low noise design for the ISA passage are proposed. The current method for the prediction of internal aerodynamic noise consists of the steady CFD and the scaling laws for the noise prediction. This combination is most cost-effective, compared with other methods, and therefore is believed to be suited for the preliminary design tool in the industrial field.

• Journal of computational fluids engineering
• /
• v.22 no.1
• /
• pp.43-50
• /
• 2017

Thermal flowfield of a micro turbojet engine was computationally investigated for exhaust nozzles with different aspect ratio and curvature. Special attention was paid to maximum and average temperature of the nozzle surface and the exhaust nozzle plume. The IR signatures of the micro turbojet engine nozzle were then calculated through the narrow-band model based on thermal flowfield data obtained through CFD analysis. Finally, in order to check the similarity of thermal flowfields and IR signature of the sub-scale micro turbojet engine model and the full-scale UCAV propulsion system, several non-dimensional parameters associated with temperature and optical property of plume were introduced. It was shown that, in spite of some differences in actual values of non-dimensional parameters, the scaling characteristics on spectral feature of IR signature and effects of aspect ratio and curvature of nozzle configuration remain similar in sub-scale and full-scale cases.

• Journal of Periodontal and Implant Science
• /
• v.29 no.4
• /
• pp.861-872
• /
• 1999

Since pathologic changes of exposed root surface inhibit cell attachment and new attachment of connective tissue have been made, many efforts were apply to change the exposed root surface condition. Scaling and root planing can not remove the endotoxin completely and forms the smear layer which prohibits the new attachment of connective tissue. Therefore, many kinds of chemicals were used for controlling the pathologic change of the root surface. The purposes of this study was to compare and observe the changes of the exposed root surface treated by scaling and root planning, Tetracycline HCl and Argon Laser. After the scaling and root planning of ten extracted premolars, the differences & the root surface among groups were observed under SEM. Control group showed smear layer and irregular amorphous surface. The dentinal tubule was not exposed. The debris and scale like texture were also observed. Tetracycline HCl treated group showed relatively smooth surface and the collagen fiber was observed in the dentinal tubule. Argon Laser treated group showed the most effective results under the conditions of 0.8 to 1.0w irradiation for 0.5 to 1.0 sec with pulse wave. The results of this study showed that the root surface change was associated with the intensity and the duration of Argon Laser irradiation. Further investigation for the surface change with the Argon Laser irradiation is recommended for understanding of clinical effect.

• Corrosion Science and Technology
• /
• v.16 no.6
• /
• pp.285-293
• /
• 2017

The effects of sulfate reducing bacteria (SRB) on the corrosion and scaling of the Q235 carbon steel has been investigated in the simulated sewage water and oil field gathering pipelines production water, using scanning electron microscopy (SEM), energy dispersive x-ray spectrometry (EDS), and three-dimensional stereoscopic microscope. Results indicated that the concentration of SRB reached the maximum value on the ninth day in simulated sewage water with a large amount of scaling on the surface of specimen. In oil field gathering pipelines, a large amount of scaling and mineralization of mineral salts and thick deposition of extracellular polymeric substance (EPS) layers were also observed on the surface of specimen. The thickness of biofilm was about $245{\mu}m$ within 30 days. After adding microbicides, the thickness of corrosion products film was only up to $48-106{\mu}m$ within 30 days, suggesting that SRB could induce biomineralization. Under-deposit corrosion morphology was uniform in the absence of microbicides while local corrosion was observed in the presence of microbicides.

• Journal of Ocean Engineering and Technology
• /
• v.35 no.1
• /
• pp.75-81
• /
• 2021

Artificial Coral Reefs (ACRs) have been introduced to help solve coastal erosion problems, but their feasibility has not been assessed with field data. This study conducted a feasibility analysis of ACRs on their erosion mitigation effects by performing a case study of Cheonjin-Bongpo beach, South Korea. A numerical-physical combined analysis was carried out using a SWAN model simulation and physical model test with a scale of 1/25 based on field observations of Cheonjin-Bongpo beach. Both Dean's parameter and the surf-scaling parameter were applied to comparative analysis between the absence and presence conditions of the ACR. The results for this combined method indicate that ACR attenuates the wave height significantly (59~71%). Furthermore, ACR helps decrease the mass flux (~50%), undertow (~80%), and maximum wave set up (~61%). The decreases in Dean's parameter (~66%) and the surf-scaling parameter suggest that the wave properties changed from the dissipative type to the reflective type even under high wave conditions. Consequently, an ACR can enhance shoreline stability.

• Journal of dental hygiene science
• /
• v.23 no.3
• /
• pp.225-235
• /
• 2023

Background: This study aimed to analyze the effects of periodontal treatment and individual- and tooth-related factors on tooth extraction in people with disabilities. Methods: The Korea National Health Insurance claims data of individuals with disabilities aged 40~64 years with chronic periodontitis in 2008 were obtained. Of these, data on the disabled who underwent scaling/root plaining, subgingival curettage/periodontal surgery, or non-periodontal treatments, and data on their teeth were selected. The extraction of 716,688 teeth from 39,097 patients was tracked until 2018, and the patient- and tooth-level factors related to tooth loss were identified using a mixed-effect logistic regression analysis. Results: Data from approximately 17% of the teeth were extracted during a follow-up period of approximately 11 years. Among the tooth-level variables, scaling/root planing treatment at baseline and periodontal treatment during the follow-up period were associated with a lower risk of tooth loss (odds ratio=0.692 and 0.769, respectively, p<0.001). Non-vital teeth increased the risk of tooth loss by 3.159 times (p<0.001). Among the patient-level variables, females were less likely to have lost their teeth than males, and those with orthopedic impairment or brain lesions/mental disabilities, a higher age group, lower income level, or residents in medium/small cities or rural areas were more likely to have lost their teeth (p<0.001). Conclusion: Through approximately 11 years of follow-up, scaling or root planing, experience with periodontal treatment at least once, female sex, older age, lower income, smaller residential areas, type of disability, and pulp vitality were found to be associated with tooth loss in individuals with disabilities aged 40~64 years with chronic periodontitis. To prevent tooth loss in individuals with disabilities, it is necessary to establish a dental treatment plan that considers the timing of periodontal treatment and the characteristics of the patient and teeth.