• Radiation Oncology Journal
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• v.12 no.2
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• pp.243-252
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• 1994

The use of high dose rate remote afterloading system for the treatment of intraluminal lesions necessitates the need for a more accurate of dose distributions around the high intensity brachytherapy sources, doses are often prescribed to a distance of few centimeters from the linear source, and in this range the dose distribution is very difficult to assess. Accurated and optimized dose calculation with stable numerical algorithms by PC level computer was required to treatment intraluminal lesions by high dose rate brachytherapy system. The exposure rate from sources was calculated with Sievert integral and dose rate in tissue was calculated with Meisberger equation, An algorithm for generating a treatment plan with optimized dose distribution was developed for high dose rate intraluminal radiotherapy. The treatment volume becomes the locus of the constrained target surface points that is the specified radial distance from the source dwelling positions. The treatment target volume may be alternately outlined on an x-ray film of the implant dummy sources. The routine used a linear programming formulism to compute which dwell time at each position to irradiate the constrained dose rate at the target surface points while minimizing the total volume integrated dose to the patient. The exposure rate and the dose distribution to be confirmed the result of calculation with algorithm were measured with film dosimetry, TLD and small size ion chambers.

• Restorative Dentistry and Endodontics
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• v.33 no.2
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• pp.125-132
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• 2008

The purpose of this study is to compare the shear bond strength of repaired composite resin with different bonding agents and evaluate the effect of bonding agents on composite repair strength. Forty composite specimens (Z-250) were prepared and aged for 1 week by thermo cycling between 5 and $55^{\circ}C$ with a dwell time of 30s. After air abrasion with $50\;{\mu}m$ aluminum oxide, following different bonding agents were applied (n = 10); SB group: Scotchbond multipurpose adhesive (3 step Total-Etch system); XE group: Clearfil SE bond (2 step Self-Etch system); XP group: XP bond (2 step Total-Etch system); XE group: Xeno III (1 step Self-Etch system). After bonding procedure was completed, new composite resin (Z-250) was applied to the mold and cured. For control group. 10 specimens were prepared. Seven days after repair, shear bond strength was measured. Data was statistically analyzed using one-way ANOVA and Tukey's test (p<0.05). The means and standard deviations of shear bond strength (MPa ${\pm}$ S.D.) per group were as follows: SB group: 17.06; SE group: 19.10; XP group: 14.44; XE group: 13.57; Control Group: 19.40. No significant difference found in each group. Within the limit of this study, it was concluded that the different type of bonding system was not affect on the shear bond strength of repaired composite resin.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.47-53
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• 2003

This study evaluated the influence of chemomechanical caries removal agent $Carisolv^{TM}$(MediTeam, Sweden) for composite resin adhesion to sound human permanent and primary dentin. The buccal/labial surfaces of 80 permanent molars and 80 primary incisors were used. Four types of adhesives and one composite resin were used; AQ Bond(Sun Medical, Japan), Clearfil SE Bond(Kuraray, Japan), Single Bond(3M, USA), Scotchbond Multi-Purpose(3M, USA) and Z100(3M, USA). One drop of $Carisolv^{TM}$(MediTeam, Sweden) was pretreated on the dentin for 0 second(control) and 60 seconds. The specimens were thermocycled for 1,000 times in baths kept 5 degrees C and 55 degrees C with a 30 seconds dwell time. Shear bond strengths were tested and the data was statistically analyzed using one-way ANOVA with subsequent post hoc Scheffe test at p<0.05. $Carisolv^{TM}$ treatment significantly decreased the shear bond strength. Shear bond strength of permanent dentin was significantly higher than that of primary dentin. Clearfil SE Bond treatment groups showed the highest shear bond strength and AQ Bond treatment groups showed the lowest shear bond strength.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.637-645
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• 2018

This study analyzes the problem of lack of anchorage caused by some anchorage closed and suggests ways to improve Masan anchorage. For this, we established the evaluation criteria, and analysed the anchorage operating rate during 5 years after estimating the capacity of barge, and suggested improvement plan after appropriateness assessment of anchorage capacity, finally verified the anchorage improvement plan. As a result of study, it is analyzed that the Masan A-2, A-4, A-6 anchorage needs to expand the anchorage due to excess the anchorage assessment criteria of 60 %. So, in order to improve the Masan anchorage, we suggested the improvement plan that extended 1.8 times by the group designated anchorage, according to integrating the A-2, A-4, A-6 anchorage and anchorage dwell time and ship type. And, the result of verification improvement plan, it is analyzed that meet the assessment criteria since decreasing the anchorage operating rate by 1/2 compared to the existing one, does not act as a risk factor in terms of maritime traffic.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.592-599
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• 2002

Objective : The purpose of this study was to evaluate the effects of several light curing methods and several adhesives on the microleakage of composite resin restorations in primary teeth. Materials and methods : In 150 extracted human primary anterior teeth, O-shaped cavities were prepared in the labial surface ; the cavity diameter and depth were 1.6mm. The cavities were filled with light-activated composite resin, Compoglass. Four kinds of adhesives were used. Each filling materials were polymerized with three light cure methods. The restorations were polished using Sof-Lex discs(3M Co., USA). The samples were thermocycled 1,000 times between $5^{\circ}C$ and $55^{\circ}C$ with a 1-minute dwell time. Then, they were immersed in a 2% methylene blue solution(pH 7) for 12hours. Subsequently they were sectioned labio-lingually through the center of the restoration with a diamond saw at low speed with a water coolant, and evaluated by stereomicroscopy. Microleakage analyses were done, using scores from 0 to 4. Results : Results showed the least microleakage in Compoglass group(P<0.05). There were less microleakage in SBMP group among the adhesive groups, but no significant difference was observed(P>0.05). And there were no significant differences among the groups depending on curing methods(P>0.05).

• Restorative Dentistry and Endodontics
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• v.27 no.5
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• pp.502-514
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• 2002

The aim of this study was to evaluate the marginal adaptation of direct class II sandwich restoration with packable composites(P-60), resin modified glass ionomer cement(Fuji-II LC), flowable compomer(Dyract Flow), flowable composites(Filtek Flow) in comparison with total bond restorations. In addition, for sandwich restorations, influence of different sandwich techniques was also evaluated. Large butt-joint box typed class II cavites with cervical margins 1mm below the cemento-enamel junction were cut into 70 extracted human molars. The cavities(7 groups, n=10) were filled using a closed/open sandwich restoration or total bond restoration technique with materials according to the manufacturer's recommandation using the single-component bonding agent for each system. Teeth were thermocycled 500 times between 5$^{\circ}C$ and 55$^{\circ}C$ with 30-second dwell time. The teeth were then coated with nail polish 1mm short of the restoration, placed in a 2% methylene blue for 24 hours, and sectioned with diamond wheel. Sections were examined with a stereoscope to determine the extent of microleakage. Dentine /Cementum margins were analyzed for microleakage on scale of 0(no leakage) to 4(entire axial wall) and interface between materials, on scale of 0(no leakage) to 3(axial wall). Results were evaluated with Kruskal Wallis Test, corrected for ties, to determine whether there were statistically significant differences among the seven groups. Pairs of groups were analyzed using the Student-Newman-Keuls Method and Dunn s Method. The results were as follows : 1. All groups showed some micoleakage in cervical portion. But there were no microleakage in interface between materials. 2. Closed sandwich restorations with Fuji-II LC and Filtek Flow had significantly lower leakage rating than total restorations with only P-60. However, open sandwich restorations with Dyract Flow showed significantly higher (P<0.05) 3. Closed sandwich restorations had significantly lower leakage rating than total restorations. However open sandwich restoration s showed significantly higher (P<0.05). 4. Sandwich restorations with Fuji-II LC were iou$.$or leakage than only P-60. Filtek Flow, Dyract Flow. But there were no statistically differences among the materials. From the results above, it could be concluded, closed sandwich restorations was effective in reducing microleakage of class II restorations. The best results showing the least microleakage were for the closed sandwich technique with Fuji-II LC and Filtek Flow.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.73-80
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• 2007

Compomer that release fluoride could be used on proximal caries of child effectively. But oral cavity is always wet, so saliva inhibits bonding of tooth and compomer. When the saliva exist on bonding, it can be occured microleakages. The purpose of this study was to evaluate the influence of salivary contamination on compomer restoration and degree of microleakage according to restoration methods. Dyract $AP^{(R)}$ and prime and $bond^{(R)}$ NT was applied by the manufacture s instructions. Elipar Trilight was applied for light curing. Saliva pool was made for reconstruction of oral cavity. Two premolar was embedded in acrylic resin. After class II cavity preperation, Dyract $AP^{(R)}$ was restored under several condition, the specimen was thermocycled 500 times with 30 second dwell time. 0.5% methylene blue was used for microleakage test. Micoleakage was measured by the ratio of the infiltration length to occlusal and gingival side interface. Data were analyzed statistically using Kruskal Wallis Test, Mann-Whitney Test. The Result were as follows ; 1. In occlusal side, there were no statistical differences. 2. In gingival side, there were no statistical differences in Group III ($ContactMatrix^{TM}$, Rubber dam, $Oraseal^{(R)}$), Group IV (No saliva contamination). 3. In gingival side, there were no statistical differences in Group I$(ContactMatrix^{TM})$, II($ContactMatrix^{TM}$, Rubber dam). 4. In gingival side, there were statistical differences in Group I$(ContactMatrix^{TM})$, II($ContactMatrix^{TM}$, Rubber dam).

• Journal of The Korean Association For Science Education
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• v.33 no.7
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• pp.1471-1485
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• 2013

The purpose of this study was to develop a HAM (Heuristic Attention Model) by analyzing the difference between eye movements according to the science achievement of elementary school students on discrimination task. Science achievement was graded by the results of the Korea national achievement test conducted in 2012 for a random sampling of classes. As an assessment tool to check discrimination task, two discrimination measure problems from TSPS (Test of Science Process Skill, developed in 1994) which were suitable for an eye tracking system were adopted. The subjects of this study were 20 students from the sixth grade who agreed to participate in the research. SMI was used to collect EMD (eye movement data). Experiment 3.2 and BeGaze 3.2 programs were used to plan experiments and analyze EMD. As a result, eye movements of participants in discrimination tasks varied greatly in counts and duration of fixation, first fixation duration, and dwell time, according to students' science achievement and difficulty of the problems. By the analysis of EMD, strategies of the students' problem-solving could be found. During problem solving, subjects' eye movements were affected by visual attention; bottom-up attention, top-down attention and convert attention, and aflunter attention. In conclusion, HAM was developed, and it is believed to help in the development of a science learning program for underachievers.

• Restorative Dentistry and Endodontics
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• v.24 no.3
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• pp.473-481
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• 1999

This study evaluated the shear bond properties of IPS Empress glass ceramic to enamel and dentin surfaces with three ceramic surface treatments, and three resin cements. The influence of thermocycling was also investigated. The purpose of this study was to investigate the influences of resin cements, ceramic surface treatments, and thermocycling on shear bond properties. Ninety freshly extracted, noncarious human molars were selected for this study. The surface treatments of ceramic were etching <5.0% hydrofluoric acid, application of silane coupling agents(Tokuso Ceramic Primer, Clearfil porcelain bond, Monobond-S), and the combination of the two methods. Empress cylinders were bonded to enamel and dentin surfaces with three kinds of resin cements(Bistite resin cement, Panavia 21, Variolink). The specimens were aged in $37^{\circ}C$ distilled water for 24 hours. Half of the specimens were then thermocycled 500times between $5^{\circ}C$ and $55^{\circ}C$ with a dwell time of 15 seconds. Each specimen was debonded in shear mode and measured shear bond properties by using the universal testing machine(Zwick 020, Germany). The data were analyzed by SPSS/PC+(one-way ANOVA, Scheffe' s test and t-test). The results were as follows : 1. Without thermocyling, there was significant difference of shear bond strength to enamel surface between Bistite Resin Cement and Panavia 21 in case of etched and silane-treatment(p<0.05). 2. Without thermocyling, the shear bond strength of a group treated with silane and etching was significantly higher than that of a group treated with silane or etching with the application of Panavia 21 and Variolink(p<0.05). 3. A group treated with etching with the application of Variolink only showed a decrease of shear bond strength after thermocycling(p<0.05).

• Journal of Biomedical Engineering Research
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• v.17 no.3
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• pp.327-336
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• 1996

This study was performed to investigate the effec% of immersion in water and thermal cycling on the mechanical peoperties of light cured restorative composite resins. Five commerically available light-cured composite resins(Photo Clearfil A : CA, Lite-Fil A . LF, Clearril Photo Posterior CP, Prisms AP.H.. PA, 2100 : ZH) were unto The specimens of 12 m in diameter and 0.7 m in thickness were made, and an immersion in $37^{\circ}C$ water for 7 days and a thermal cycling of 1000 cycles at 15 second dwell time each in $5^{\circ}C$ and $55^{\circ}C$ baths were performed. Biaxial flexure test was conducted using the ball-on-three-ball method at the crosshead speed of 0.5mm/min. In order to investigate the deterioration of composite resins during the thermal cycling test, Weibull analysis for the biaxial flexure strengths was done. Fracture surfaces and the surfaces before and after the thermal cycling test were examined by SEM. The highest Weibull modulus value of 10.09 after thermal cycling tests which means the lowest strength variation, was observed in the CP group, and the lowest value of 4.47 was obsered in the LF Group. Biaxial flexure strengths and Knoop hardness numbers significantly decreased due to the thermal cycling ($\textit{p}$< 0.01), however, they recovered when specimens were drie4 The highest biaxial flexure strength of 125.65MPa was observed in the ZH group after the thermal cycling test, and the lowest value of 64.86MPa was observed in the CA group. Biaxial flexure strengths of ZH and CP groups were higher than those of PA, CF, and CA groups after thermal cycling test($\textit{p}$< 0.05). Knoop hardness numbers of CP group after the thermal cycling test was the highest(95.47 $\pm$ 7.35kg/$mm^2$) among the samples, while that of CA group was the lowest(30.73 $\pm$ 2.58kg/$mm^2$). Knoop hardness numbers showed the significant differences between the CP group and others after the thermal cycling test(($\textit{p}$< 0.05). Fracture surfaces showed that the composite resin failure developed along the matrix resin and the filler/resin interface region, and the cracks propagated in the conical shape from the maximum tensile stress zone.