• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.33-40
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• 2003

Fusobacterium nucleatum, one of the bacteria causing halitosis, produces the volatile sulfur compounds (VSC) such as $H_2S$ in the media containing sulfur components, and forms FeS by binding with iron component. The various factors of oral cavity affect the concentration of sulfur compounds produced by Fusobacterium nucleatum. In this study, the effect of nutrients and pH on the production of sulfur compounds by Fusobacterium nucleatum was studied with the following results. 1. The optical density of broth was increased to $0.817{\pm}0.032$ and $1.297{\pm}0.024$ by adding 1.0% sodium thiosulfate and 0.05% L-cysteine hydrochloride in the media, respectively. 2. Though the optical density of broth was $0.799{\pm}0.032$ by adding volatile sulfur compounds (VSC) only in the media, it was increased to $1.775{\pm}0.003$ and $1.648{\pm}0.022$ by adding xylitol combined with glucose and fructose, respectively. 3. The concentration of VSC was above 20,000 ppb in the media above pH 5.5. The optical density of broth was still high in the media with L-cysteine hydrochloride of higher concentration, being low in the media of lower pH. 4. The concentration of VSC was high when there was distilled water or saline solution on the media, and their amount was small. These results suggest that the production of sulfur compounds by Fusobacterium nucleatum was inhibited by xylitol and acid.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.25-32
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• 2003

S. mutans is the most important causative bacteria of dental caries among the oral bacteria. S. salivarius is a normal inhabitant in the human oral cavity. Nine strains of S. salivarius in this study were isolated from the oral cavities of children and identified, and their effect on S. mutans and S. oralis was studied. 1. The mean weight of produced artificial plaque on the wires in the beaker was 204.9 mg in the culture of S. mutans only, whereas being reduced to 1.9 mg through 20.6mg in the combined culture of S. mutans and each S. salivarius isolate (p<0.05). The viable cell didn't show the difference between them after culturing. 2. When S. mutans was cultured in the media containing culture supernatant of each S. salivarius isolate in M17 broth, the mean weight of produced artificial plaque was 117.1 mg on the wires, whereas being 47.7 mg in the media containing culture supernatant of each S. salivarius isolate in M17 broth containing 5% sucrose. 3. The polymer produced by S. salivarius isolates was on the thin layer chromatography. 4. Inulin and levan didn't inhibit the formation of artificial plaque by S. mutans in the beaker test. These results suggested that fructan-producing S. salivarius isolates inhibited the formation of artificial plaque by S. mutans.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.2
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• pp.322-328
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• 2007

The first molar is important for mastication and also it plays roles to formation of vertical occlusion and growth of jaw bone after mixed dentition. Impaction of mandibular first molar can result in a short lower facial height, formation of a follicular cyst, pericoronal inflammation, resorption of the roots of neighboring teeth and malocclusion. The options of treatment plans are as follows; observation, surgical exposure, orthodontic traction, surgical relocation and extraction. Surgical exposure could be considered as a basic treatment plan. For surgical exposure it is important to maintain patent channel between the crown and the normal eruptive path into the oral cavity, many techniques including cementation of a celluloid crown, packing with zinc oxide-eugenol surgical pack are used. In these cases, we could observe spontaneous eruption of mandibular first molar using surgical exposure with or without removal of odontoma. Also we could obtain the main patency effectively and conveniently by using surgical pack and translucent retainer.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.18-29
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• 2008

The purpose of this study was to compare the polymerization shrinkage of several filling methods using strain gauges. In this study, a light-emitting diode(LED) curing unit(Elipar Freeligh2, 3M EPSE, USA) and plasma arc lamp(PAL) curing unit(Flipo, LOKKI, France) were used for curing, Filtek $Z350^{TM}$(3M EPSE, USA) composite resin was used for the cavity filling. Sixty permanent bicuspid teeth, that were extracted for orthodontic treatment, were studied. The cavities were prepared on the occlusal surface and were filled using the following methods : 1) bulk filling, 2) parallel filling, 3) oblique filling The strain was recorded on the buccal, lingual, mesial and distal surfaces and the strain values were computed into stress values. The shear bond strength of each filling method was tested using a Micro Universal Testing machine. The results can be summarized as follows: 1. In the strain changes, all LED and PAL curing groups showed an increase on the buccal surface and a slow decrease as time elapsed. 2. In the strain changes of the mesial and distal surfaces, the decreases and increases were shown repeatedly and reduced as time elapsed. 3. There were no significant statistical strain changes among filling methods in the LED or PAL curing groups. 4. There were significant statistical strain changes between the LED and PAL curing groups on the buccal surface(p<0.05). 5. From the shear bond strength results, in the LED curing group, filling method 3 showed lower surface stress than filling method 1 and 2(p<0.05). In the PAL curing group, there were no significant statistical strain changes between each filling method. 6. The surface stress of each group was lower than the shear bond strength.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.3
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• pp.387-393
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• 2009

The purpose of this study was to assess the relationship between interdental spaces and proximal caries in maxillary anterior primary teeth. 555 children aged 3-7 inhabit in Iksan were divided into two groups, depending on the presence of interdental space which was detected by a dental explorer. They were determined to have proximal caries if cavity was formed or the enamel surface was softened. The results were as follows : 1. Regarding interdental spaces, 77.4% had primate spaces; 54.4% had developmental spaces between central and lateral incisor, and 39.0% between central incisors. 2. Interproximal caries incidences in right primary canine, lateral incisor, and central incisor were 6.3%, 14.7%, and 33.5%, respectively. Also interproximal caries incidences in left primary central incisor, lateral incisor, and canine were 33.7%, 16.0%, and 4.7%, respectively. 3. Children with more interdental spaces had less caries incidence, but the relationship was weak(r=-0.024). 4. The mean caries incidence was higher in absence of interdental space of maxillary primary incisors than in presence of space. The mean caries incidence with no interdental space was twice as high as that with presence of interdental space.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.257-265
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• 2020

This study was performed to evaluate the restoration combined with resin infiltration (RI) of early cavitated smooth surface caries lesion in terms of microleakage. Flowable resin and resin-modified glass ionomer cement (RMGIC) were compared. Sound 20 extracted 3rd molars were divided into 2 groups randomly. Artificial decalcified lesion was induced. Cavities were prepared on the mesial and distal surfaces, and randomly set as experimental and control group. RI was applied to the experimental group before cavity restoration. The control group was restored without RI. In group I and II, flowable resin and RMGIC was used for restoration respectively. After thermocycling and silver nitrate immersion, microleakage was assessed by μ-CT. Depth of microleakage was lower in experimental group than control group only in group II (p = 0.05). Microleakage depth was lower in group II than group I in both experimental and control groups (p = 0.05). RI pretreatment before restoration of early cavitated caries lesions might reduce the microleakage and help long-term maintenance of restoration. In this study, RMGIC was less polymerization shrinkage. Restoration with RMGIC after RI pretreatment reduced the microleakage of the restoration compared to the flowable resin.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.10 s.101
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• pp.1050-1058
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• 2005

This paper presents how to design and implement a very compact, cost effective and broad band receiver module for IEEE 802.16 FWA(Fixed Wireless Access) in the 40 GHz band. The presented receiver module is fabricated in a multi-layer LTCC(Low Temperature Cofired Ceramic) technology with cavity process to achieve excellent electrical performances. The receiver consists of two MMICs, low noise amplifier and sub-harmonic mixer, an embedded image rejection filter and an IF amplifier. CB-CPW, stripline, several bond wires and various transitions to connect each element are optimally designed to keep transmission loss low and module compact in size. The LTCC is composed of 6 layers of Dupont DP-943 with relative permittivity of 7.1. The thickness of each layer is 100 um. The implemented module is $20{\times}7.5{\times}1.5\;mm^3$ in size and shows an overall noise figure of 4.8 dB, an overall down conversion gain of 19.83 dB, input P1 dB of -22.8 dBm and image rejection value of 36.6 dBc. Furthermore, experimental results demonstrate that the receiver module is suitable for detection of Digital TV signal transmitted after up-conversion of $560\~590\;MHz$ band to 40 GHz.

• Tuberculosis and Respiratory Diseases
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• v.51 no.1
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• pp.65-69
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• 2001

The incidence of lung cancer and its mortality rate are increasing in Korea. At the time of diagnosis, 40% patients of lung cancer patients had metastatic lesions. The common metastatic sites are the contralateral lung, bone, liver, adrenal gland and the brain. Metastasis to oral mucosa is rarely encountered in lung cancer and metastasis to the gingiva is more uncommon. Approximately 1% of malignant carcinomas in the oral cavity are the result of metastases, and 10-25% of metastatic cancers originate from lung cancer. Clinically metastatic gingival lesions are benign including hemangioma, pyogenic granuloma, giant-cell granuloma or a peripheral fibroma. Often metastases to the gingiva are diagnosed too late and by the time they are detected, they have metastases to other organs. Here we report a case of small cell lung carcinoma that had metastased to the gingiva with review of relevant literature.

• Korean Journal of Biological Psychiatry
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• v.25 no.3
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• pp.60-71
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• 2018

Objectives A growing body of evidence has suggested that morphologic changes in cerebellum may be implicated with pathophysiology of major depressive disorder (MDD). The aim of this study is to investigate a difference in the volume and cortical thickness of the specific region of cerebellum between patients with MDD and healthy controls (HC). Methods A total of 127 patients with MDD and 105 HC participated in this study and underwent T1-weighted structural magnetic resonance imaging. We analyzed volume and cortical thickness of each twelve cerebellum regions divided by left and right and the volume and cortical thickness of the whole cerebellum from T1-weigted image of participants. One-way analysis of covariance was used to investigate the volume and cortical thickness difference of total and specific regions between two groups adjusting for age, gender, medication, and total intracranial cavity volume. Results We found that the patients with MDD had significantly greater volume in the left cerebellum lobule III region [false discovery rate (FDR)-corrected p = 0.034] compared to HC. Also, our findings indicate that cortical thickness of left lobule VIIB (FDR-corrected p = 0.032) and lobule VIIIB (FDR-corrected p = 0.032) are significantly thinner in the patients with MDD compared with the HC. No significant volume and cortical thickness differences were observed in other sub-regions of the cerebellum. The volumes and cortical thickness of whole cerebellum between patients with MDD and HC did not differ significantly. Conclusions We observed the region-specific volume and cortical thickness difference in cerebellum between the patients with MDD and HC. The results of our study implicate that the information about structural alterations in cerebellum with further replicative studies might provide a stepping stone toward a specific marker to diagnose MDD.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3B
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• pp.293-303
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• 2011

An efficient diagonalized approximate factorization algorithm (DAF) is developed for the solution of three-dimensional incompressible viscous flows. The pressure-based, artificial compressibility (AC) method is used for calculating steady incompressible Navier-Stokes equations. The AC form of the governing equations is discretized in space using a second-order-accurate finite volume method. The present DAF method is applied to derive a second-order accurate splitting of the discrete system of equations. The primary objective of this study is to investigate the computational efficiency of the present DAF method. The solutions of the DAF method are evaluated relative to those of well-known four-stage Runge-Kutta (RK4) method for fully developed and developing laminar flows in curved square ducts and a laminar flow in a cavity. While converged solutions obtained by DAF and RK4 methods on the same computational meshes are essentially identical because of employing the same discrete schemes in space, both algorithms shows significant discrepancy in the computing efficiency. The results reveal that the DAF method requires substantially at least two times less computational time than RK4 to solve all applied flow fields. The increase in computational efficiency of the DAF methods is achieved with no increase in computational resources and coding complexity.