• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.2
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• pp.228-237
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• 2001

It is well known that glass-ionomer cement and compomer can release fluoride which can inhibit the progression of dental caries. The purposes of this study were to evaluate whether the fluoride from fluoride-containing filling materials can penetrate the dentin bonding adhesive and the dentin bonding adhesive can increase the bond strength of resin-modified glass ionomer. The amount of fluoride release from resin-modified glass ionomer and compomer was measured during 28 days of period and statistically analyzed by t-test. The bond strength of each material with/without dentin bonding adhesive was measured and also statistically analyzed by t-test. The distribution of fluoride from each material into the tooth was explored by electron probe microanalysis system(EPMA). The experimental teeth used were second primary molars about to exfoliate. The amount of fluoride release from each material was diminished by dentin bonding adhesive during 28 days(p<0.05) and the bond strength was not increased by dentin adhesive in resin-modified glass ionomer. The bond strength of group VI was not detectable. The distribution of fluoride from each material into teeth was according to dentino-enamel junction and dispersed into pulp from pulpal floor. The widest distribution was shown in resin-modified glass ionomer cement filled without the application of dentin bonding adhesive.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.251-260
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• 2002

Geotextile tribes are made of sewn geotextile sheet and hydraulically or mechanically filled with dredged materials. They have been applied in hydraulic and coastal engineering in recent years(shore protection structure, detached breakwater, groins, and jetty). Therefore, it is composed of geotextile and confined fill material. Recently, new preliminary design criteria supported by model and prototype tests, and some stability analysis calculations have been studied. The stability analysis of geotextile tube is composed of geotechnical and hydrodynamic analysis. The stability check points are sliding failure, overturning, bearing capacity failure against the wave attack. In this paper are presented the stability analysis method by empirical equation and 2-D equilibrium analysis for geotextile tube. Also, the hydraulic model tests were performed to verify the theoretical stability analysis with geotextile tube shape, filling ratio, significant wave height, and so on. The results of this study show that the stability of geotextile tube depends on the tube shape, contact area, projection area. The theoretical analysis and hydraulic model test show almost the same results.

• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.467-476
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• 2009

The aim of this study was to measure the dentinal tubular fluid flow (DFF) during and after amalgam and composite restorations. A newly designed fluid flow measurement instrument was made. A third molar cut at 3 mm apical from the CEJ was connected to the flow measuring device under a hydrostatic pressure of 15 $cmH_2O$. Class I cavity was prepared and restored with either amalgam (Copalite varnish and Bestaloy) or composite (Z-250 with ScotchBond MultiPurpose: MP, Single Bond 2: SB, Clearfil SE Bond: CE and Easy Bond: EB as bonding systems). The DFF was measured from the intact tooth state through restoration procedures to 30 minutes after restoration, and re-measured at 3 and 7days after restoration. Inward fluid flow (IF) during cavity preparation was followed by outward flow (OF) after preparation, In amalgam restoration, the OF changed to IF during amalgam filling and slight OF followed after finishing. In composite restoration, application CE and EB showed a continuous OF and air-dry increased rapidly the OF until light-curing, whereas in MP and SB, rinse and dry caused IF and OF, respectively. Application of hydrophobic bonding resin in MP and CE caused a decrease in flow rate or even slight IF. Light-curing of adhesive and composite showed an abrupt IF. There was no statistically significant difference in the reduction of DFF among the materials at 30 min. 3 and 7 days after restoration (p > 0.05).

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.124-134
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• 1994

The shade of restorative materials is very important for successful restoration esthetically harmonized with the natural tooth. The purpose of this study was to evaluate the color stability and the opacity change of conventional chemical setting and visible light curing glass-ionomer cements for restorative esthetic filling. Specimens of each brand (GC Fuji II and Fuji II LC) were uniformly prepared and divided into three groups: In group l(control group), the specimens received no surface treatment; in group 2, the specimens were coated with varnish and the excess gently blown off; and in group 3. the specimens were coated with light-cured bonding resin and irradiated by a visible light curing unit for 20 seconds on both sides. All specimens were stored in distilled water at $37^{\circ}C$ and checked after for 24 hours. 2 months. 4 months, 6 months. and 8 months. The color characteristics($L^*,\;a^*,\;b^*$) and the opacity(Y%) of all the samples were measured by a spectrocolorimeter and the total color differences(${\Delta}E^*$) and opacity changes(${\Delta}Y%$) were computed. The following results were obtained : 1. The total tolor differences in all groups increased with time. 2. The total color differences of the LC groups after immersion for 8 months in distilled water at $37^{\circ}C$ were lower than those of GC groups(p<0.01), and the total color differences of the varnish or the light-cured bonding resin coated groups were lower than those of the control group with glass-ionomer cements which had no surface treatment(p<0.01). 3. In all groups the translucency decreased with time. 4. In the control group and the varnish coating group. the opacity changes of the GC groups were lower than those of the LC groups(p<0.01) and in the light-cured bonding resin coated group, there was no significant difference between the GC group and the LC group. 5. The opacity changes of the varnish or the light-cured bonding resin coated groups were lower than those of the control group(p<0.01). These results suggest that color change and opacity of conventional chemical setting and light cured glass-ionomer cement were increased with time, and the color changes and the opacity changes of a control group after immersion for 8 months in distilled water at $37^{\circ}C$ were greater than those of the varnish or the light-cured bonding resin coated groups.

• Restorative Dentistry and Endodontics
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• v.35 no.6
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• pp.479-485
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• 2010

Objectives: The aim of this study was to compare the push-out bond strengths of resin cement/fiber post systems to post space dentin using different application methods of resin cement. Materials and Methods: Thirty extracted human premolars were selected and randomly divided into 3 groups according to the technique used to place the cement into root canal: using lentulo-spiral instrument (group Lentulo), applying the cement onto the post surface (group Direct), and injecting the material using a specific elongation tip (group Elongation tip). After shaping and filling of the root canal, post space was drilled using Rely-X post drill. Rely-X fiber post was seated using Rely-X Unicem and resin cement was light polymerized. The root specimens were embedded in an acrylic resin and the specimens were sectioned perpendicularly to the long axis using a low-speed saw. Three slices per each root containing cross-sections of coronal, middle and apical part of the bonded fiber posts were obtained by sectioning. The push-out bond strength was measured using Universal Testing Machine. Specimens after bond failure were examined using operating microscope to evaluate the failure modes. Results: Push-out bond strengths were statistically influenced by the root regions. Group using the elongation tip showed significantly higher bond strength than other ways. Most failures occurred at the cement/dentin interface or in a mixed mode. Conclusions: The use of an elongation tip seems to reduce the number of imperfections within the selfadhesive cement interface compared to the techniques such as direct applying with the post and lentulospiral technique.

• The Korean Journal of Urological Oncology
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• 제15권3호
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• pp.178-186
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• 2017

Purpose: Poloxamer 407 (P407) thermo-sensitive hydrogel formulations were developed to enhance the retention time in the urinary bladder after intravesical instillation. Materials and Methods: P407 hydrogels (P407Gels) containing 0.2 w/w% fluorescein isothiocyanate dextran (FD, MW 4 kDa) as a fluorescent probe were prepared by the cold method with different concentrations of the polymer (20, 25, and 30 w/w%). The gel-forming capacities were characterized in terms of gelation temperature (G-Temp), gelation time (G-Time), and gel duration (G-Dur). Homogenous dispersion of the probe throughout the hydrogel was observed by using fluorescence microscopy. The in vitro bladder simulation model was established to evaluate the retention and drug release properties. P407Gels in the solution state were administered to nude mice via urinary instillation, and the in vivo retention behavior of P407Gels was visualized by using an in vivo imaging system (IVIS). Results: P407Gels showed a thermo-reversible phase transition at $4^{\circ}C$ (refrigerated; sol) and $37^{\circ}C$ (body temperature; gel). The G-Temp, G-Time, and G-Dur of FD-free P407Gels were approximately $10^{\circ}C-20^{\circ}C$, 12-30 seconds, and 12-35 hours, respectively, and were not altered by the addition of FD. Fluorescence imaging showed that FD was spread homogenously in the gelled P407 solution. In a bladder simulation model, even after repeated periodic filling-emptying cycles, the hydrogel formulation displayed excellent retention with continuous release of the probe over 8 hours. The FD release from P407Gels and the erosion of the gel, both of which followed zero-order kinetics, had a linear relationship ($r^2=0.988$). IVIS demonstrated that the intravesical retention time of P407Gels was over 4 hours, which was longer than that of the FD solution (<1 hour), even though periodic urination occurred in the mice. Conclusions: FD release from P407Gels was erosion-controlled. P407Gels represent a promising system to enhance intravesical retention with extended drug delivery.

• Journal of The Geomorphological Association of Korea
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• v.20 no.4
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• pp.51-70
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• 2013

The characteristics of deposits formed by the Daejon-cheon and Soobuk-cheon, dissecting the mountains such as Byungpung Mt. and Samin Mt. in western part of Damyang county, Jeonmam province. Results from field survey and bore hole logging by KIGAM are used in interpreting depositional environment, in this study. By the result of deposits near of the channels Daejon-cheon and Soobuk-cheon, and main channel of Youngsan River, the depth of sediment layers in this area is 4~7m, far thinner than formerly estimated. Weathered material of local rocks forms the base of the sedimentary layers. It can be assumed that the location channel of the Youngsan river has been stable ever since the start of the sedimentary events. Sediment particles of tributaries are angular than those of Youngsan River. Particles are larger and sorting is poor. It is interpreted as mount flash flood deposits. Main sources of sediments at the valley bottom or deposition dominated area are the terrace deposits or slope deposits over the gentle foot-slope or front of surrounding mountains. Some particles show polygonal cracking on the surface originated from the strong chemical weathering, while most of these has high angularity. It means various geomorphic processes operate to produce and transport the particles in this area.Isolated hills within the sedimentary plains are made with weathered materials of local bedrock. In the case of foot-slope of the hills, thin sedimentary layers are found. So it can be concluded that surface features of deposition zone of the Daejon-cheon and Soobuk-cheon is formed by the filling of lower part of the valley and its feature partly controlled by the relief of the weathering front.

• 한국노년학
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• v.38 no.3
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• pp.395-408
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• 2018

The purpose of this study is to investigate the effects of staffs' general characteristics and institutional characteristics on the staff members' recognition of the level of ethical management in the elderly welfare institutions and to provide basic materials for raising standard of ethical management in the elderly welfare institutions. For this purpose, we conducted a questionnaire survey using structured self-filling-type questionnaires for 245 staffs of elderly welfare institutions in Seoul and Gyeonggi-do. This study sets general characteristics of staffs and institutional characteristics as the independent variables and the staff members' recognition of the level of ethical management as the dependent variable. The variables are investigated through the descriptive statistics such as frequency, percentage and average analysis, and the difference of effect on the staff members' recognition of ethical management in the elderly welfare institutions by each independent variable was analysed by t-test, ANOVA and multiple regression analysis. The results of the study shows that in terms of general characteristics of staffs, the higher male to female ratio and the higher educational level; and in institutional characteristics, the less experience in basic ethics education and the better ethical working environment of the institution are the positive factors for that the staff members estimate the level of ethical management of their workplace high. Based on these results, for making staff members recognize the level of ethical management in the elderly welfare institutions higher, we should create actual atmosphere of the ethical working environment in the institution and implement not formal but step-by-step intensive ethics education that make employees can apply it in the real situations. In conclusion, this study gives the practical suggestions for improving the staff members' recognition of ethical management level in the practice field of elderly welfare on the fast-changing trends including downsizing and privatization.

• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.3
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• pp.143-152
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• 2019

Purpose: The aim of this study is to investigate the characteristics of patients and teeth referred to a university dental hospital for endodontic problem. Materials and Methods: From January, 2017 to December, 2018, patients who were referred to a university dental hospital for endodontic problem were collected from clinical records. A total of 1171 patient records were analyzed. The status of the referred teeth was divided into three groups according to whether they were treated endodontically based on radiographs and clinical records at the time of referred visit. Results: 69.9% of the referred teeth were maxillary and mandibular first and second molars. The average time from referral to actual visit is 9.03 days and 65.6% of the case referred with referring letter. The most primary reasons of referral were persistent clinical symptom (pain, swelling, and sinus tract) (37.9%), diagnosis difficulty (16.7%), blockage of canal space (13.8%) and difficult tooth anatomy (11.4%). In the case of referral before endodontic treatment, the most primary reason of referral was failure to make a proper diagnosis. If the teeth were referred in the middle of endodontic treatment, the most primary reason of referral was persistent clinical symptom and blockage of canal space. In the case of referral after root canal filling, the most primary reason of referral was persistent clinical symptom. Conclusion: In the case of molars, the rate of persistent clinical symptom and blockage of canal space were the most primary reason of referral, and the rate of apical surgery and management of trauma was high in the case of anterior teeth.

• Korean Journal of Heritage: History & Science
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• v.47 no.3
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• pp.60-85
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• 2014

The study is for tracing the mutational process, considering the transformational process of wooden chamber tombs in Gyoungju region during 2~6 century. In addition, class features and the meaning of tombs were studied. First of all, the wooden chamber tombs were classified into 10 different styles(1A~IVC), based on the filling materials, the ways of structure, and the structure of burial chamber. There were only one or two tombs that belongs to the highest classes 'Ga'~'Da' in each period, which has the numeral features. Furthermore, the styles of the central wooden chamber tombs according to the period and the region have distinctive features and have changed so far. It shows that there are the rank among the tombs in the regions. In other words, regarding the ranks of the class 'Ga'~'Cha', there were strict rules and the limitations on the size of the tombs and the number and the quality of the burial relics. It means that the inner-outer size or the structure of the tombs and the number, quality of the burial goods depended on the buried person's birth or social classes, or achievements. Based on Shila social classes, the class 'Ga' tombs were for the highest classes when considered the size, burial relics, and the quality. The class 'Na' and 'Da' tombs were for the higher classes, 'Ma' for middle classes, 'Ba', 'Sa' for lower classes. In addition, 'Ah', 'Ja' tombs were for higher commoner, 'Cha' for lower commoner. Thus, class 'Ga'~'Sa' is the leading class of Shila.