• Communications of Mathematical Education
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• v.19 no.1 s.21
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• pp.69-100
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• 2005

이 연구는 내신성적이 우수함에도 불구하고 수능성적이 저조한 학생들이 문제 해결과정에서 나타내는 특성과 수학불안 요인을 분석하는데 있다. 연구의 대상은 인천시 5고등학교 자연계열 2학년 학생 중 내신성적이 상위 10%안에 드나 수능성적(모의수능성적)은 그렇지 못한 학생 5명이고, 이들의 수학적 성향, 수학 성취도, 개인별 특성 등에 대한 사전 면담자료, 문제풀이과정에 대한 사후 심층면담자료, 현장노트, 수학불안검사를 바탕으로 그들의 특성과 수학불안 요인을 분석한 결과는 다음과 같다. (1) 내신성적은 좋으나 수능성적이 저조한 학생들의 수학 문제 해결 과정에서 나타나는 특성은 수학전 영역에서의 개념부족, 공식암기 부족 등으로 인하여 문제풀이계획을 세우지 못하거나 설사 문제를 푼다고 해도 계산 실수, 착각, 부주의 등으로 인해 정확한 답을 구하지 못하는 것으로 나타났다. (2) 내신성적은 좋으나 수능성적이 저조한 학생들은 어느 정도의 수학 불안은 가지고 있었다. 불안의 요인은 개념부족, 응용력 부족 등 개인적 인지능력에 의한 저조한 수학 성취수준과 수학 공부시간 부족, 풀이시간 부족 등의 환경적 요인에 때문인 것으로 밝혀졌다. 특히 수학개념이 부족한 학생일수록 수학불안 현상이 심하게 나타났다. 따라서 이들 학생들의 수학 문제풀이 과정 중에 나타나는 계산 실수, 부주의, 착각은 그들의 수학 자신감에 많은 악영향을 미치게 되므로, 교사가 이를 그냥 방관할 것이 아니라 적극적으로 확인하고 지도해줄 필요가 있다. 또 교실 수업에서도 수능시험에서 다루고 있는 수학 내적, 외적 문제해결문제, 추론문제, 응용문제, 통합문제에 대한 문제풀이 경험을 하게하여 수학불안을 해소해줄 필요가 있다.)값을 보였으나, 10,000Hz의 높은 측정주파수에서는 더 큰 $E_a$값을 나타냄으로서 반응온도변화에 민감함을 보여주었다.원으로부터 부유물을 증가로 사료되었으며, 이에 대한 대책마련이 시급한 것으로 사료되었다. 수질이 휴양용수로서 사용하는 데에 적합하도록 충분한 차집시설과 환경 기초시설의 설치 운영이 필요할 것으로 판단된다.TEX>$K_s$값이 높고 $V_m/K_s$비율은 낮아 수게에서 질소가 저농도 일 때에는 다른 미세조류와 비교하면 경쟁력이 떨어지고 질소에 대한 기질 친화력은 약한 것으로 나타났다. 낙동강 하류지역에서 M. aeruginosa가 대발생하는 시기에 수중 영양염의 농도 변동은 M. aeruginosa의 영양생리 kinetics 특성과 잘 부합하는 것으로 나타났다.부분을 보완하기 위한 연구가 이루어져야 할 것으로 보인다. 연마방법 간에 상호 연관성이 없었다. FE-SEM관찰에서 레진전색제를 적용한 후의 표면은 모든 군에서 대체적으로 평활한 표면을 나타내었다. 4. 동일한 복합레진과 연마방법으로 처리된 군에서 레진전색제 적용 전과 후의 표면조도 값은 M1B군이 M1군보다, S1B군이 S1군보다 통계학적으로 높게 나타났으며, M4B군과 M5B군은 각각 M4군과 M5군 보다. 그리고 S5B군은 S5군 보다 통계학적으로 낮게 나타났다 (p<0.05). 본 연구를 종합하여 보면, 복합레진의 종류에 따라 표면조도의 순서는 다르게 나타났고, polyester strip 하에서 복합레진이 중합된 경우 가장 낮은 표면조도 값과 평활한 표면을 제공하였으며 전반적으로 anishing bur는 가장 높은 Ra값과 거친 표면을 제공하였다.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.3
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• pp.469-477
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• 2002

One of the major deficiencies of composite restorative resins is their insufficient resistance to wear. Of the multitude of factors that have been associated with wear, subsurface degradation within the restoration is considered to be one. The aim of this study was to evaluate the resistance to degradation of four commercial composite resins in an alkaline solution. The brands studied were Z100(3M), Clearfil AP-X(Kuraray), Tetric Ceram(Vivadent), Aelit flo(Bisco). Resistance to degradation was evaluated on the basis of the following parameters: (a) mass loss(%) - determined from pre-and post-exposure specimen weights: (b) Si loss(ppm) - obtained from ICP-AE analysis of solution exposed to specimens; and (c) degradation depth(${\mu}m$) - measured microscopically (SEM) from polished circular sections of exposed specimens. The results were as follows: 1. The sequence of the mass loss was in ascending order by AE, EL, TC, Z100. There was statistically significant difference of mass loss between AE, CL group and TC, Z100 group(p<0.05). 2. The sequence of the degree of degradation layer depth was in ascending order by AE, CL, TC, Z100. But there was no statistically significant difference of degree of degradation layer depth between AE and CL(p<0.05). 3. For the Si concentration, Z100 was the highest of all. 4. The correlation coefficient between mass loss and degradation depth was relatively high(r=0.71 p<0.05).

• Restorative Dentistry and Endodontics
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• v.33 no.5
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• pp.419-427
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• 2008

This study analyzed the influence of dental adhesive/primer on the bond strength between indirect resin composite and the resin cement. Seventy disc specimens of indirect resin composite (Tescera Dentin, Bisco) were fabricated. And bonding area of all specimens were sandblasted and silane treated for one minute. The resin cements were used with or without application of adhesive/primer to bonding area of indirect resin restoration, Variolink-II (Ivoclar-Vivadent) : Exite DSC, Panavia-F (Kuraray) : ED-Primer, RelyX Unicorn (3M ESPE) Single- Bond, Duolink (Risco) : One-step, Mulitlink (Ivoclar-Vivadent) : Multilinh Primer. Shear bond strength was measured by Instron universal testing machine. Adhesive application improved shear bond strength (p<0.05) But Variolink II and Panavia-F showed no statistically significant difference according to the adhesive application. With the above results, when resin inlay is luted by resin cement it seems that application of dental adhesive/primer is necessary in order to improve the bond strength.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.3
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• pp.410-418
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• 2000

An in vitro study was performed to evaluate the effect of four variables on the temperature rise produced by polishing of restorations. The four variables were : restorative material, base, thickness of remaining dentin, continuous polishing or intermittent polishing. Class V cavities were cut on extracted molar and restored with composite resin, resin-modified glass ionomer cement, compomer, amalgam on the various bases (glass ionomer cement, zinc oxide eugenol cement, zinc phosphate cement) Dentin thickness under the restoration was 0.5mm, 1.5mm. Polishing was done with an aluminum oxide-coated disc. Polishing time was continuous or intermittent for up to 1 minute. Intra-pulpal temperature increased almost linearly in all cases. Amalgam produced highest temperature rises at the pulp, while the composite resin, resin-modified glass ionomer cement and compomer were not different for each other. The rate and extent of temperature rising of amalgam restoration was reduced by presence of a cement base. Zinc oxide eugenol cement bases showed the highest temperature rise, while glass ionomer cement, zinc phosphate cement were not different to the untreated tooth Thickness of remaining dentin was only significant for the amalgam restoration. Continuous polishing produced higher temperature rise than intermittent polishing.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.45-53
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• 2000

Enamel microabrasion is a means by which superficial enamel discoloration is removed using hydrochloric acid and fine pumice. As enamel microabrasion alone may not be sufficient in cases of deeper discoloration, composite resin restoration is recommended in areas where there is remaining discoloration. The purpose of this study was to investigate the effects of different methods and number of applications of enamel microabrasion on the shear bond strength of composite resin to enamel. Untreated control was designated as group 1. 5-second applications of a mixture of 18% HCl and fine pumice were performed 5 and 10 times on groups 2 and 3, respectively. A commercially available mixture of 10% HCl and abrasives(PREMA) was applied using a 10 : 1 gear reduction handpiece 5 and 10 times on groups 4 and 5, respectively, with each application lasting 20 seconds. After etching with 37% phosphoric acid, composite resin was bonded. Thermocycling was performed and shear bond strength was measured. The following results were obtained : 1. Group 2 showed the highest bond strength$(24.36{\pm}3.34)$, while group 3 showed the lowest$(19.35{\pm}3.43)$, Shear bond strength decreased in the following order: 2>4>5>1>3. 2. Group 2 showed bond strength significantly higher compared to groups 1 and 3(p<0.05). 3. There were no significant differences between groups 2 and 3, which had been microabraded using HCl and pumice, and groups 4 and 5, to which PREMA had been applied, when bond strengths were compared(p>0.05). 4. When modes of fracture were examined, adhesive failure was observed in groups 3 and 4, while cohesive failure was observed in groups 1, 2, 3 and 4. Only mixed failures were found group 5. 5. When viewed using a SEM, groups 2 and 3, which had been microabraded using HCl and pumice, showed surface appearances similar to that of enamel etched with phosphoric acid. Groups 4 and 5, treated with PREMA, exhibited a smooth surface similar to that of group 1. All oops showed similar, typical surface characteristics following phosphoric acid etching.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.511-519
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• 2008

Statement of problem: An incompatibility between the initiator systems of self-curing composite resins and light-curing adhesives was supposed recently. Purpose: The purpose of the study was to evaluate the influence of activators for self/dual bonding on dentin shear bonding strengths. Material and methods: Fifty human molars were divided into 5 groups. A flat dentin surface was created for each tooth. A self-curing composite resin (Luxacore) was bonded with the following adhesives (n = 10); One-Step, Prime&Bond NT, AdheSE, Prime&Bond NT and AdheSE were also used in combination with activators. Shear bond strengths were measured after 24 hours of water storage. The specimens were loaded in shear in the Instron until failure at a 1 mm/min crosshead speed. Data were compared using one-way ANOVA and Tukey HSD test (${\alpha}$= 0.05). Results: The dentin adhesive systems in order of decreasing median bond strength were One-Step > Prime&Bond NT with activator, AdheSE with activator > Prime&Bond NT, AdheSE. Among adhesives, One-Step had the highest bond strength. Prime&Bond NT with activator had higher bond strengths than Prime&Bond NT that was used alone, and so was AdheSE. Conclusion: Shear bond strengths were increased in Prime&Bond NT and AdheSE when these were used with activators comparing used without activators. But using activators was not effective clinically comparing One-Step.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.2
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• pp.125-133
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• 2014

The purpose of this study was to investigate the effect of various surface treatment methods on the shear bond strength of orthodontic brackets in vitro. Ninety six specimens, 6 mm in diameter and 5 mm in height, were made with composite resin ($Filtek^{TM}$ Z350 XT, 3M ESPE, USA) and treated with an aging procedure. After aging, the specimens were randomly separated in six groups: (1) control with no surface treatment, (2) 37% phosphoric acid gel, (3) 4% hydrofluoric acid gel, (4) sodium bicarbonate particle abrasion, (5) diamond bur, and (6) 1 W carbon dioxide laser for 5s. The metal brackets were bonded to composite surfaces by means of an orthodontic adhesive (Transbond XT, 3M Unitek, USA). Shear bond strength values were evaluated with a universal testing machine (R&B Inc., Korea). Analysis of variance showed a significant difference between the groups. Group 5 had the highest mean shear bond strength (11.9 MPa), followed by group 6 (11.1 MPa). Among the experimental groups, group 2 resulted in the weakest mean shear bond strength (5.22 MPa). The results of this study suggest that the repair shear bond strength of the aged composite resin was acceptable by surface treatment with a carbon dioxide laser.

• Restorative Dentistry and Endodontics
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• v.30 no.6
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• pp.450-460
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• 2005

The aim of this study was to evaluate the effect of cavity shape, bond quality of bonding agent and volume of resin composite on shrinkage stress developed at the cavity floor. This was done by measuring the shear bond strength with respect to iris materials (cavity shape , adhesive-coated dentin as a high C-factor and Teflon-coated metal as a low C-factor), bonding agents (bond quality: $Scotchbond^{TM}$ Multi-purpose and Xeno III) and iris hole diameters (volume; 1mm or 3mm in $diameter{\times}1.5mm$ in thickness). Ninety-six molars were randomly divided into 8 groups ($2{\times}2{\times}2$ experimental setup). In order to simulate a Class I cavity, shear bond strength was measured on the flat occlusal dentin surface with irises. The iris hole was filled with Z250 restorative resin composite in a bulk-filling manner. The data was analyzed using three-way ANOVA and the Tukey test. Fracture mode analysis was also done When the cavity had high C-factor, good bond quality and large volume, the bond strength decreased significantly The volume of resin composite restricted within the well-bonded cavity walls is also be suggested to be included in the concept of C-factor, as well as the cavity shape and bond quality. Since the bond quality and volume can exaggerate the effect of cavity shape on the shrinkage stress developed at the resin-dentin bond, resin composites must be filled in a method, which minimizes the volume that can increase the C-factor.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.3
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• pp.538-553
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• 1999

The purpose of this study was to compare the shear bond strength and the anticariogenicity of glass ionomer cement with conventional bonding resin and fluoride releasing resin. After the shear bond strength test, scanning electron microscopic observation was performed for the evaluation of the fracture patterns in each group. Under the polarizing light microscope, artificially induced carious lesions were evaluated and the lesion depths of the samples were measured using image analyzing program(Image-Pro $PLUS^{TM}$, USA). 50 sound maxillary premolars were used for the bond strength test and another 30 for the anticariogenic test. Data collected were analyzed statistically using Oneway-ANOVA and Scheffe test. The results were as follows: 1. Glass ionomer groups(G-III, IV, V) generally showed the lower bond strength values than resin groups(G-I, II). 2. Among the two resin groups, G-I showed the higher bond strength than G-II without statistically significant difference between them(p>.05). 3. Within glass ionomer groups, statistical significance was found between G-III and G-V with the superior bond strength in G-V (p<.05). 4. Under the SEM, adhesive failure was the predominant fracture pattern in G-I and II, whereas cohesive failures were mainly observed in G-III. In G-IV and V, mixed type of pattern where the both fracture patterns coexisted within samples could be seen. 5. In evaluation of the depth of artificially developed carious lesion, glass ionomer group showed shallower depth than resin groups with statistical significance between G-III and G-I, II(p<.05). Among resin groups, fluoride releasing resin(G-II) showed the shallower depth than conventional resin(G-I)(p<.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.632-640
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• 2002

The objective of the study was to apply the vibration technique to reduce the viscosity of bonding adhesives and thereby compare the bond strength and resin penetration into dentinal tubules achieved with those gained using the conventional technique. Eighty-eight noncarious extracted human permanent molar teeth were sectioned to remove the coronal enamel and were embedded in 1-inch PVC pipe with acrylic resin. The occlusal surfaces were placed so that the tooth and the embedding medium were at the same level to form one flat surface, and the samples were subsequently polished with silicon carbide abrasive papers. The samples were randomly assigned to 4 groups(n=22). On Group 1 and 2, Single Bond(3M-ESPE, St. Paul, USA) was used, and on Group 3 and 4, One-Step(Bisco Inc., Schaumburg, USA) was used, and each was applied according to its manufacturer's instructions. For Group 2 and Group 4, vibration was applied with ultrasonic scaler for 10 seconds, and the adhesive was light-cured for 10 seconds. Resin composite was condensed on to the prepared surface in two increments using a mold kit(Ultradent Products Inc., USA) and each was light-cured for 40 seconds. After 24 hours in tap water at room temperature the specimens were thermocycled, and shear bond strengths were measured with a universal testing machine(Instron 4465, Canton, USA). To investigate infiltration patterns of the adhesive materials, the surface of specimen was examined with scanning electron microscope. The results were as follows. 1. The shear bond strengths of vibration groups(Group 2, Group 4) were significantly greater than those of the non-vibration groups(Group 1, Group 3)(p<0.05). 2. The shear bond strengths of Single Bond and One-Step were not significantly different (p>0.05). 3. The vibration groups showed greater number of resin tags in tubules and lateral branches under SEM.