• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.142-147
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• 2000

Durability characteristics of controlled low strength material(flowable fill) with high volume fly ash content was examined. The mix proportions used for flowable fill are selected to obtain low-strength material in the 10 to 15kgf/㎥ range. The optimized flowable fill was consisted of 60kgf/㎥ cement content, 280kgf/㎥ fly ash content, 1400kgf/㎥sand content, and 320kgf/㎥water content. Subsequently, durability tests including permeability warm water immersion, repeated wetting & drying, freezing & thawing for high volume fly ash-flowable fill are conducted The test results indicated that flowable fill has has acceptable durability characteristics.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.4
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• pp.446-454
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• 2017

Recently, there have been many studies on bulk-fill resin composites. However, studies on the proper materials for pediatric patients are rare. The aim of this study was to compare the cavity wall adaptation of bulk-fill resin composites with conventional resin composite in class II cavities of primary molars using microcomputed tomography (micro-CT). Standardized class II slot cavities were prepared in 80 exfoliated primary molars and randomly divided into 4 groups. The control group was restored with conventional resin composite, Filtek Z-350 XT (FZ), and the three groups were restored with bulk-fill resin composites, Filtek bulk-fill posterior (FB), Tetric N-Ceram Bulk Fill (TNC), Filtek bulk-fill flowable (FBF). All specimens were thermocycled and then immersed in 50% silver nitrate ($AgNO_3$) solution. Micro-CT was used to measure the penetration volume of the total silver nitrate and the degree of cervical marginal leakage and the number, size, and position of the voids were evaluated. The results revealed that the volume of silver nitrate were significantly different between FB and FZ (p < 0.05). The results also revealed that the penetration length of silver nitrate FBF showed statistically lower than the FZ and FB (p < 0.05). There was no significant difference between the groups in number and size of voids. In conventional resin composite, most of the voids were present inside the restoration (83.3%), but the voids in the bulk-fill resin composites incidence were higher in the gingivoaxial angle. The cavity wall adaptation demonstrated in class II restorations of primary molar by new bulk fill resin composites was similar to conventional incremental technique. Bulk-fill resin composites might be an clinical option for a faster restoration in deciduous teeth.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.1
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• pp.1-9
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• 2000

The purpose of this study was to analyze the characteristics of soil erosion on the fill-slope of forest road by elapsed years after road construction. Thirteen plots were established on the fill-slope of the newly-constructed forest road, and surveyed for two years(1997~1998). In these plots, the data about soil erosion, surface runoff, vegetation coverage, slope structural characteristics and rainfall were collected. In 1997, the major causes for soil erosion were found by the correlation coefficients with the amount of surface runoff from the fill-slope, vegetation coverage, slope length, slope degree, total rainfall and max. 1 hour rainfall. But, in 1998, the major causes for soil erosion were vegetation coverage and slope degree. Using the stepwise multiple regression method, in 1997, the amount of soil erosion from the fill-slope was complexly expressed as a exponential function of statistically significant the amount of surface runoff from the fill-slope, total rainfall, slope degree of fill-slope and vegetation coverage, but, in 1998, simply expressed as a exponential function of vegetation coverage.

• Restorative Dentistry and Endodontics
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• v.45 no.1
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• pp.5.1-5.8
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• 2020

Objectives: The obturation quality of MTA, Biodentine, Total Fill BC root canal sealer (RCS), and warm gutta-percha (WGP) in teeth with simulated internal root resorption (IRR) was evaluated by using micro-computed tomography. Materials and Methods: Standardized IRR cavities were created using 40 extracted maxillary central incisor teeth and randomly assigned into 4 groups (n = 10). IRR cavities were filled with MTA, Biodentine, Total Fill BC RCS (bulk-fill form) and WGP + Total Fill BC RCS. Percentage of voids between resorptive cavity walls and obturation material (external void), and inside the filling materials (internal voids) were measured. Results: Total Fill BC sealer in the bulk-fill form presented significantly highest values of external and internal void percentages (p < 0.05). Biodentine showed a significantly lowest external void percentage (p < 0.05). WGP + Total Fill BC RCS presented significantly lower values of internal void percentages than all groups (p < 0.05), except Biodentine (p > 0.05). Conclusion: None of the filling materials were created void-free obturation in resorption cavities. Biodentine may favor its application in teeth with IRR over Angelus MTA and bulkfill form of Total Fill BC.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.3
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• pp.81-90
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• 1999

The purpose of this study is to examine the uses of fly ash asa type of construction material. This paper presents the results of research performed to identify optimum mix proportions for production of lowable fill with high volume fly ash content . The fly ash used in this study met the requirements of KS L 5405 and ASTM C 618 for Class F material. The flowable fill with high volume fly ash content was investigated for strength and flowability characteristics. Tests were carried out on flowable fill designed to have 10 ~15kgf/$\textrm{cm}^2$ compressive strength at 28 days with fly ash contents of approximately 260kgf/㎥. Slump was held at 25$\pm$1cm for all mixtures produced to range from 5kgf/$\textrm{cm}^2$ to 14kgf/$\textrm{cm}^2$ compressive strengths at 28 days. To produce flowable fill with high volume fly ash , first the influential variables were identified in an experimental study based on factorial design. Among the proportioning variables investigated, cement ,fly ash, and sand contents were found to have statistically significant effect on strength and slump of flowable fill . Subsequently, response surface analysis techniques were used to devise an experimental program that helped determine the optimum combinations of the selected influential variables based on material properties and cost. The optimized flowable fill were then technically evaluated. It is shown that flowable fill has acceptable compressive strength , slump flow, hardening time, and permeability.

• Restorative Dentistry and Endodontics
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• v.46 no.2
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• pp.24.1-24.11
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• 2021

Objectives: The present study aimed to evaluate the survival rate and clinical performance of class 1 composite restorations restored with the Filtek Bulk Fill composite material using either the bulk fill technique or the incremental technique at baseline (1 week) and at 3, 6 and 12 months of follow-up. Materials and Methods: Forty-two patients with at least 2 carious teeth were selected. Following randomization, one tooth was restored with the Filtek Bulk Fill composite using the incremental fill technique, and the other tooth was restored with the same material using the bulk fill technique. Patients were recalled for follow-up at baseline (1 week) and 3, 6, and 12 months and evaluated using the FDI criteria. Results: The data were analyzed using the McNemar χ² test. No statistically significant differences were found between the scores of teeth restored with either technique. At baseline and at 3, 6, and 12 months of follow-up; there were no significant difference in the clinical status of both groups of restorations. Conclusions: Within the limitations of this study, using the bulk fill technique for restorations with the Filtek Bulk Fill material seems to be equally efficient to using the incremental fill technique.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.4
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• pp.365-373
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• 2016

Composites are the most useful restorative material. However, composites have some disadvantages such as polymerization shrinkage, long working time, and susceptibility to water and contamination, which are stood out more especially when treating children. To solve these problems, bulk-fill composites have been developed. The aim of this study is to compare mechanical properties of bulk-fill and conventional composites. Bulk-fill composites (SureFil SDR flow (SDR), Tetric N-Ceram bulk fill (TBF)) and conventional composites (Filtek Z-350 (Z-350), Unifil Flow (UF), Unifil Loflo Plus (UL)) were used. The Vickers hardness tester was used to measure the microhardness of materials, and Fourier transform infrared spectroscopy was used to measure the degree of conversion. Polymerization shrinkage was measured by using a linometer. Flexural and compressive properties were measured by using the universal testing machine. Data were statistically analyzed by ANOVA and Scheffe's post hoc test. The level of significance was set to p < 0.05. Most conventional composites showed higher microhardness than bulk-fill composites. However, bulk-fill composites showed a higher top/bottom microhardness ratio than conventional composites. Bulk-fill composites showed a higher top/bottom degree of conversion ratio than conventional composites. The polymerization shrinkage was highest in UL and lowest in Z-350. The polymerization shrinkage of flowable composites was higher than that of non flowable composites. The compressive properties were highest in Z-350 and lowest in SDR and UL. In terms of flexural properties, Z-350 was the highest. However, none of the bulk-fill composites exhibited mechanical properties as good as those of conventional composites. Nonetheless, the ratio of microhardness and degree of conversion, which are important properties of bulk filling, were higher in bulk-fill composites. Therefore, the bulk-fill composites might be considered suitable restorative materials in pediatric dentistry.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.2
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• pp.87-95
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• 2013

The aim of this study is to examine the behavior of reservoir fill dam with the water level raising by use of the centrifugal model test and the numerical simulation. In this study, LIQCA2D-SF based on the cyclic elasto-plastic constitutive model proposed by Oka et al. (1999) is applied for numerical simulation. In order to investigate the displacements and the pore water pressures in the fill dam due to the water level raising velocity, three model tests in centrifugal field of 50g for fill dams were conducted. A comparison between the test result and the simulation result has provided the influence on the displacement and the pore water pressure of the fill dam with increasing up of the water level.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.697-704
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• 2005

The objective of this study is firstly to frame up the seismic safety of rock-fill dams. It is necessary to analyze seismic response and evaluate seismic performance of rock-fill dams during earthquake. In this study, seismic damage and dynamic analysis of rock-fill dams using structural analysis package such as FLAC were performed. According detailed analysis, the vibration through the dam structure seems to be very critical depending on the shape of the dams. For more precise evaluation of seismic fragility of rock-fill dams, further research is still needed.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.505-510
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• 2007

Concrete track will be constructed in Gyungbu High Speed Railway II(GHSR II) stage construction site from Daegu to Busan. Concrete track is supported by substructure consisting of the original ground and embankment and does not allow the settlement of track because of its structural type. The embankment is composed of rock and soil mixture and settlement is feasible. So management of settlement of embankment is key point in successful construction of the concrete track. Compaction management of mixed fill materials is important in minimizing the settlement of embankment. In this study, in order to assess the compaction characteristics of mixed fill materials, large laboratory compaction tests were conducted. Mixed fill materials were obtained from two construction sites in GHSR II construction site. Modeled mixed fill materials having different rock type, fine content, maximum particle diameter, and moisture contents were prepared. From the test results, compaction characteristics of mixed fill materials were analysed.