• Restorative Dentistry and Endodontics
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• v.29 no.3
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• pp.205-211
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• 2004

This study evaluated the microleakage and interfacial gap between enamel and composite resin under the dry and wet condition of the enamel surface. V shaped class 5 cavities were prepared on the occlusal portion of extracted human molars. Samples were divided into three groups：D group (air dry for 10-15s), BD group (blot dry with moist cotton pellet), and DR group (air dry for 10-15s and rewet with Aqua-Prep F for 20s), Cavities were filled using Aelitefil composite resin after applied One-Step. Microleakage was tested by 2% methylene blue dye solution and the data were statistically analysed by Kruskal-Wallis test and Mann-Whitney test. Also Enamel-resin interface was observed under SEM. Group BD showed statistically lower microleakage than group D (p < 0.05). but there was no statistically significant difference between group BD and DR (p > 0.05). At the enamel-resin interface, group D showed the gap of $2{\;}{\mu}m$ thickness, but group BD and DR showed close adaptation. In conclusion, the use of blot dry and rewetting agent (Aqua-Prep F) resulted in decreased microleakage and improved adhesion between enamel and resin when using One-Step.

• Journal of Korean society of Dental Hygiene
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• v.8 no.4
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• pp.219-228
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• 2008

The purpose of this study was to examine the oral health status and oral health care of adults using dental clinics and the relationship between their oral health state and oral health care. The subjects in this study were 219 patients who visited dental clinics in Gyeonggi province between February and April 2008. A dental checkup and survey were implemented, and SPSS 12.0 program was utilized to analyze the collected data. The findings of the study were as follows: 1. The DT, MT and FT rates of the respondents who used oral hygiene supplies respectively stood at 30.7, 24.6 and 24.6 percent, which were all low. The gaps between them and the others were statistically significant. The DMFT index of the users of oral hygiene supplies was 12.3, which was high, but the difference between them and the others was not statistically significant. 2. The DT rate of those who got a dental checkup on a regular basis stood at 20.8 percent, which was low. The gap between them and the others was statistically significant. Both the MT and FT rates of the former numbered 28.8 percent, which was low, but the gap between them and the others was statistically insignificant. The DMFT index of the respondents who got a regular dental checkup was 12.8, which was high, and the gap between them and the others was statistically significant. 3. The DT and FT rates of respondents who had ever had their teeth scaled respectively stood at 24.6 and 27.1 percent, which were both low, and the differences between them and the others were statistically significant. The MT rate of the former was 27.1 percent, which was low, but the gap between them and the others was statistically insignificant. The DMFT index of those who had ever had their teeth scaled was 12.2, which was high, and the gap between them and the others was statistically significant. The above mentioned findings suggested that there was a very close relationship between oral health care and oral health status. Therefore people in general should be encouraged to pay more attention to their own oral health care, and they should be well informed about how to take care of the oral cavity to promote their oral health.

• Journal of Korean Medicine Rehabilitation
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• v.18 no.3
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• pp.19-39
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• 2008

Objectives : It has been reported that CG was effective in decreasing injury to neural tissues. To investigate neural responses in the injured spinal cord, an extract of CG was examined to determine its effect on neural responses in the injured spinal cords of rats. Methods : After CG treatment was applied to the spinal cord of rats given a contusion injury, the re-growth responses of injured neural tissues and corticospinal tract axons was observed by measuring the number of GAP-43, Cdc2, and phospho-Erk1/2 proteins, CST axons, GFAP-stained astrocytes, and Glial scarring in the injured spinal cord. Results : Levels of GAP-43, Cdc2, and phospho-Erk1/2 proteins were found to have increased in the injured spinal cord region. The number of GFAP-stained astrocytes also increased within and around the injury cavity. Glial scarring, which was identified by CSPG immunofluorescence staining, was reduced by CG treatment. Anterograde tracing by Dil dye showed that the elongation of the CST axons in the dorso-medial white matter area was almost completely prevented at the injury site. Collateral sprouting was observed in the spinal cord rostrally close to the injury site, and CG treatment further increased axonal arborization in the corresponding region. In vivo migration of CST axons and astrocytes using an implanted polymer tube system showed more of an increase in enhanced migration of axons and astrocytes in CG-treated group compared to the injury control group. Conclusions : These results suggest that CG activated neural responses - including astrocyte migration - and promotes axonal regenerative activity in the injured spinal cord area.

• Journal of the Korean Vacuum Society
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• v.9 no.1
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• pp.60-68
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• 2000

The optical constants ($E_g^d$, n, K) of the polycrystalline CdSe thin films deposited on the glass substrate by the electron-beam evaporation technique are determined over 400~2,500 nm photon wavelengths. In order to explain the variation of the optical contents with film thickness and substrate temperatures, the surface microstructural parameter are investigated by AFM (atomic forced microscope( images for the films deposited by different growth conditions. It is shown that the variations of optical constants are close related to changes of the surface morphology of the CdSe thin films. The decrease in the band gap with film thickness is connected with quantum size effects due to increase of the grain size. The refractive index of CdSe films decrease with increasing the grain size of the films, and the dispersion of the refractive index followed a single oscillator model according to the Sellmeier formulation.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.142-149
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• 2000

Two dimensional slow viscous flow around two counter-rotating equal cylinders is Investigated based on Stokes' approximation. An exact formal expression of the stream function is obtained by using the bipolar cylinder coordinates and Fourier series expansion. From the stream function obtained, the streamline patterns around the cylinders are shown and the pressure distribution In the flow field is determined. By Integrating the stress distribution on the cylinder, the force and the moment exerted on the cylinder are calculated. The flow rate through the gap between the two cylinders is determined as the distance between two cylinders vary. It Is also revealed that the velocity at the far field has finite non-zero value. Special attention is directed to the case of very small distances between two cylinders by way of the lubrication theory.

• Tribology and Lubricants
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• v.17 no.5
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• pp.391-398
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• 2001

Two dimensional slow viscous flow around two counter-rotating equal cylinders is investigated based on Stokes'approximation. An exact formal expression of the stream function is obtained by using the bipolar cylinder coordinates and Fourier series expansion. From the stream function obtained, the streamline patterns around the cylinders are shown and the pressure distribution in the flow field is determined. By integrating the stress distributions on the cylinder, the force and the moment exerted on the cylinder are calculated. The flow rate through the gap between the two cylinders is also determined as the distance between two cylinders varies. Special attention is directed to the case of very small distance between two cylinders concerned with the lubrication theory and the minimum pressure is calculated to explain a possible cavitation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.281-289
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• 1992

In an attempt to simulate the flows in the computer hard disk storage system, flow visualization and quantification by image processing technique were applied. Model geometry was constructed while the dynamic similitude was maintained. Circumferential velocities were mapped out in the transient spin-up phase. During the spin-up phase, fluid close to the rotating inner hub approached the solid body rotation, while the fluid in the outer region showed the velocity deficit compared to the rotating speed of the disks. Effects of presence of read/write head arm assembly between the gap were studied by changing the location of the head. The experimental results could serve as a benchmark for the alidation of numerical codes.

• Architectural research
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• v.25 no.2
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• pp.19-27
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• 2023

London's BID, introduced in the early 2000s, has grown significantly to fill the gap between government services which have been decreased by the global recession and localism, and the demand for better services to strengthen competitiveness on a global level. Based on this background, this study comparatively analysed two BIDs in London with contrasting regional characteristics to find how BID works differently for the regeneration and sustainable development of regional business districts according to regional characteristics. As a result, the two BIDs ultimately had the goal of improving the local business environment and strengthening the competitiveness of local businesses and had a common point of working in close partnership with the public sector such as the local government. However, depending on the local situation and characteristics, it has been observed that there are differences in the strategies of work and the roles and relationships in the partnership with the public sector.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.4
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• pp.567-572
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• 2011

The purpose of the study is aimed at estimating the reasonable price and forecasting the sales rate of the new apartment, using transaction data of the existing apartment that is close to perfectly competitive markets. In the present paper, therefore, attempts were made to determine the relationship between the existing apartment market and the new housing market. Also conducted an empirical analysis that complemented the problems of precedent studies.

• Journal of Aerospace System Engineering
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• v.4 no.1
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• pp.1-9
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• 2010

As the rocket KSLV-1 called NARO was launched lately, development of domestic rocket technology has been accelerated elastically. Since the rocket technology needs a lot of empirical data, a variety of experiments should be done and lots of time have to be spent for accumulating the foundation of technology. However using a computer can be the solution to close a gap of technique because the simulation can be executed in short time against real experiments and calculate a multiplicity of cases easily. In this research, the transient analysis of turbopump-fed liquid rocket system was worked by the one dimensional modeling. The rocket system consists of the modulized components that are engine, turbopump and so on. For 70 ton class system, the rocket transient process of starting was studied and the performance analysis in steady condition was achieved. In addition, the estimation of nozzle internal flow was investigated by using a nozzle coefficient.