• Journal of Microbiology and Biotechnology
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• v.25 no.11
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• pp.1871-1879
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• 2015

The complex roles of flagella in the pathogenesis of Campylobacter jejuni, a major cause of worldwide foodborne diarrheal disease, are important. Compared with the wild-type, an insertional mutation of the flgA gene (cj0769c) demonstrated significant decrease in the biofilm formation of C. jejuni NCTC11168 on major food contact surfaces, such as polystyrene, stainless steel, and borosilicate glass. The flgA mutant was completely devoid of flagella and non-motile whereas the wild-type displayed the full-length flagella and motility. In addition, the biofilm formation of the wild-type was inversely dependent on the viscosity of the media. These results support that flagellar-mediated motility plays a significant role in the biofilm formation of C. jejuni NCTC11168. Moreover, our adhesion assay suggests that it plays an important role during biofilm maturation after initial attachment. Furthermore, C. jejuni NCTC11168 wild-type formed biofilm with a net-like structure of extracellular fiber-like material, but such a structure was significantly reduced in the biofilm of the flgA mutant. It supports that the extracellular fiber-like material may play a significant role in the biofilm formation of C. jejuni. This study demonstrated that flgA is essential for flagellar biosynthesis and motility, and plays a significant role in the biofilm formation of C. jejuni NCTC11168.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.1
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• pp.11-23
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• 1989

This paper presents the results of the numerical analysis on the behaviour of mooring system of offshore guyed tower. Finite element method is used and geometric nonlinearities are considered in the analysis of mooring line. The governing equilibrium equations are derived by the principle of virtual work, and modified Newton-Raphson method and Newmark-${\beta}$ method are employed in response calculations. The drag and inertia effects of fluid are included using a Morrison type equation. The influences of changing typical parameters like initial inclination and tension of line at the guy attachment point, the length of clump weight, its unit weight and the anchor line length are examined. The effects of idealising the clump weight as a point load(lumped clump weight) on the behaviour of mooring lines are also discussed. Numerical examples demonstrate the validity and capability of the mathematical formulation.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.12
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• pp.1294-1301
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• 2008

Under passive RFID environment, this paper presents a new localization of a mobile robot traversing over the floor covered with tags, which is superior to existing methods in terms of estimation performance and cost effectiveness. Basically, it is assumed that a mobile robot is traveling along a series of straight line segments, each segment at a certain constant velocity, and that the number of tags sensed by a mobile robot at each sampling instant is at most one. First, for a given line segment with known starting point, the velocity and position of a mobile robot is estimated using the spatial and temporal information acquired from the traversed tag. Some discussions are made on the validity of the basic assumptions and the localization for the initial segment with unknown starting point. Second, for a given tag distribution density, the optimal tag arrangement is considered to reduce the position estimation error as well as to make easy the tag attachment on the floor. After reviewing typical tag arrangements, the pseudorandom tag arrangement is devised inspired from the Sudoku puzzle, a number placement puzzle. Third, through experiments using our passive RFID localization system, the validity and performance of the mobile robot localization proposed in this paper is demonstrated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.4
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• pp.333-338
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• 2011

This paper describes the design process of floor damping material optimization to reduce structure borne noise. This process uses finite element analysis(FEA) along with experimental techniques to complement each other. The objective of this approach was to develop an optimized damping material application layout and thickness at the initial design stage. The first step is to find the sensitivity areas of vehicle body without damping material applied using FEA. In order to determine the high vibration areas of the floor panel, the velocity was measured using a scanning laser vibrometer from 20 Hz to 300 Hz. To excite the floor panel vibration, shaker was placed at the front suspension attachment point. The second step is the optimization process to determine the light weight solution of damping material. The design guideline of damping material was suggested that the lightweight solution was verified using test result of road noise. Design engineer could efficiently decide the design variable of damping material using parameter analysis results in early design stage.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.2
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• pp.154-161
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• 2014

Naval ships have hull appendages which are more exposed to the outside because of its small block coefficient compared with commercial ships. These exposed hull appendages like skeg, strut and shaft line affect the maneuverability of a ship. The effect of hull appendages has considered at initial design stage to estimate more accurate maneuverability. In this paper, sensitivity analysis is used to analyze the effect on maneuverability by hull appendages. 3 DOF maneuvering equations based on Mathematical Modelling Group (MMG) model are used and propeller & rudder model are modified to reflect the characteristics of twin propeller & twin rudder. Numerical maneuvering simulations (Turning test, Zig-zag test) for benchmark naval vessel, David Taylor Model Basin (DTMB) 5415 are performed. In every simulation, it is calculated that stability indices and maneuverability characteristics (Tactical Dia., Advance, 1st Overshoot, Time of complete cycle) with respect to the parameters (area times lift coefficient slope, attachment location) of hull appendages. As a result, two regression formulas are established. One is the relation of maneuverability characteristics and stability indices and the other is the relation of stability indices and hull appendages.

• Journal of Periodontal and Implant Science
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• v.40 no.5
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• pp.249-253
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• 2010

Purpose: The purpose of this study was to evaluate the improvement of periodontal health of generalized aggressive periodontitis (GAgP) diagnosed patients treated with non-surgical periodontal therapy accompanying systemic antibiotics administration. Methods: Two patients with GAgP were chosen for this study. Clinical indices were taken and a radiographic examination was performed at the baseline of the study and they were treated by periodontal therapy accompanying systemic antibiotics administration. Post-surgical visits were scheduled at regular intervals to check clinical and radiographic changes. Results: Through non-surgical periodontal therapy accompanying systemic antibiotics administration, GAgP patients showed decreased probing pocket depth, sulcus bleeding index, and increased attachment level and clinical index when comparing the initial and six month follow up data. In the six month follow-up radiographic examination after non-surgical periodontal therapy, resolution of the bony defect was observed. Conclusions: Non-surgical therapy combined with systemic antibiotics administration in GAgP patients is suggested to be an effective approach to enhance the periodontal health.

• Journal of Periodontal and Implant Science
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• v.23 no.1
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• pp.97-108
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• 1993

One of the important initial events required for periodontal regeneration is the attachment and subsequent spreading of periodontal ligament cells on the root surface. The purposes of this study is to investigate the attachment and spreading pattern of human periodontal ligament cell on the surface of glass slides. After establishment of a cell line of the primary cell culture from the periodontal ligament of 1st premolar teeth which were extracted for the purpose of orthodontic treatment, author dispersed the cells at $5{\times}10^3\;cells/ml$ into the each 35mm culture petri-dish containing 2 glass slides. To observe the morphological changes of the cells which attached to the surfaces of glasses at every designed time schedule, author used the inverted phase contrast microscope and scanning electron microscope. During the whole experiment culture condition was at $37^{\circ}C$, 100% Humidity, 5% $CO_2$ gas incubator. The following results were obtained. Periodontal ligament cells showed spherical outline and started to attach to glass surface by basal sytoplasmic extension after 10min in culture. After 30min in culture, periodontal ligament cells were attached to glass surface by well - developed filopodia which protruded from the lamellipodia. The cell surface is covered with bubble-like structures and occasional microvillus can be seen with diffculty among these structures. After 1.5hr in culture, peridontal ligament cells shhowed radially well-spread cytoplasm and the nucleus was centered on its cytoplasm. Unspread central region of the cell was covered with numerous microvilli. The change of cell attachment and spreading pattern was manifest at 6hr in culture. At this time, periodontal ligament cell showed elongated outline and an oval-shaped nucleus. After 12hr in culture, periodontal ligament cells showed more stretched fibroblast-like appearance with polarity. Two long lamellipodia can be seen around the both terminal ends of cells. After 24hr in culture, periodontal ligament cells showed spindle shapes and an oval-shaped nucleus was slanted toward one side of the cell.

• Journal of Periodontal and Implant Science
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• v.27 no.1
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• pp.129-150
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• 1997

The purpose of this study was to evaluate the effects of tetracycline(TC}, flurbiprofen, and PDGF-BB loaded biodegradable membranes on the cell-attachment, the activity of loaded PDGF-BB, in vivo release kinetics, and guided bone regenerative potentials. To evaluate the cell attachment to membranes, the number of gingival fibroblasts attached to each membrane(10% TC, 10% flurbiprofen, $200ng/cm^2$ PDGF-BB loaded membranes, drug-unloaded membrane) was counted by coulter counter and the morphologic pattern of attached cells was examined under SEM. To determine whether the activity of loaded PDGF-BB is sustained, the cellular growth and survival rate of gingival fibroblasts was used for both standard PDGF-BB and loaded PDGF-BB. For evaluation of in vivo release kinetics, drug-loaded membranes were implanted on the dorsal skin of the rats. On 1, 3, 7, 10, 14, 21, and 28 days after implantation, the amount of remaining drugs were measured by HPLC assay for TC and flurbiprofen, and by ${\gamma}-scintillation$ counter for $PDGF-BB^{1125}$. For evaluation of guided regenerative potential, the amount of new bone in the calvarial defect(5mm in diameter) of the rat was measured by histomorphometry 1 and 2 weeks after implantation of membranes. The number of cells attached to the PDGF-BB loaded membrane was largest as compared with the other mernbranes.(p< 0.05) The activity of loaded PDGF-BB was not significantly different from the activity of standard PDGF-BB.(p<0.05) After initial burst release of drug during the first 24 hours, drugs were gradually released for 4 weeks. Especially the release rate of PDGF-BB was nearly constant during 4 weeks. PDGF-BB loaded membranes(200, $400ng/cm^2$) were effective in guided bone regeneration as compared with drug-unloaded membrane. These results implicate that drug-loaded biodegradable membranes might be a useful for guided bone regeneration.

• Korean Journal of Environmental Biology
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• v.27 no.1
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• pp.88-94
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• 2009

The process of atherosclerosis begins through secretion of inflammatory cytokine or adhesion of leukocyte from damage in blood vessels and transmigration. This study was conducted to investigate the effects of delphinidin chloride (DC) in the initial process of atherosclerosis on the expression of ICAM-1 (Intracellular Adhesion Molecule-1) and VCAM-1 (Vascular Adhesion Molecule-1) related to adhesion of leukocyte at the HUVEC (human umbilical vein endothelial cell line. As a result, cell growth inhibition rate at 50 ${\mu}M$ was respectively 4, 3 and 5% without cell toxicity. As a result of morphological observation monocyte-endothelial cell adhesion assay and optical microscope carried out to measure attachment of mononuclear cells to endothelial cells induced by Tumor necrosis factor-alpha (TNF-$\alpha$) at concentrations without cell toxicity, DC concentration-dependently suppressed attachment. When effects on the expression of VCAM-1 and ICAM-1, cell adhesion molecules induced from endothelial cells by TNF-$\alpha$, were comparatively analyzed using western blot analysis and RT-PCR methods, protein of VCAM-1 and ICAM-1 and expression at the level of mRNA were concentration-dependently reduced. Taken together, the results of this studies provide evidence that DC possess an anti-metastatic activity.

• Implantology
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• v.18 no.2
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• pp.120-138
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• 2014

Purpose: The purpose of this study was to review the outcomes of a series of studies on tissue regeneration conducted in multiple institutions including the Department of Periodontology, College of Dentistry, Yonsei University. Materials and Methods: Studies were performed divided into the following three subjects; 1) Development of three-dimensional nano-hydroxyapatite (n-HA) scaffold for facilitating drug release and cell adhesion. 2) Synergistic effects of bone marrow-derived mesenchymal stem cells (BMMSC) application simultaneously with platelet-rich plasma (PRP) on HA scaffolds. 3) The efficacy of silk scaffolds coated with n-HA. Also, all results were analyzed by subjects. Results: Hollow hydroxyapatite spherical granules were found to be a useful tool for the drug release and avidin-biotin binding system for cell attachment. Also, BMMSC simultaneously with PRP applied in an animal bone defect model was seen to be more synergistic than in the control group. But, the efficacy of periodontal ligament cells and dental pulp cells with silk scaffolds could not be confirmed in the initial phase of bone healing. Conclusion: The ideal combination of three elements of tissue engineering-scaffolds, cells and signaling molecules could be substantiated due to further investigations with the potentials and limitations of the suggested list of studies.