• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.154-154
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• 2015

현재 액체로켓 엔진 연소기 내벽은 bonding layer NiCrAlY과 Top layer $ZrO_2$가 플라즈마 용사 방식으로 형성 된다. 이는 뛰어난 열 차폐 특성과 작업시간이 짧은 장점이 있지만, bonding layer와 Top layer 사이의 열팽창 계수 차이로 인한 균열 발생 가능성이 내재 되어 있고, 연소실 내벽에 균일한 두께의 코팅층을 형성하기 어렵고 설비가 비싸다는 단점으로 인하여 세라믹 코팅 층을 금속 코팅 층으로 대체 하고자 한다. 금속 코팅층은 모재와의 밀착성이 높고, 우수한 산화 및 부식방지 기능을 가지며 저렴하다는 장점이 있다. 또한 코팅 후 연마 작업이 가능해 연소실 내부형상을 설계조건 대로 유지 할 수 있는 특징이 있다. 따라서 본 연구에서는 연소실 내벽에 적용할 모재, 무전해 Ni-P 도금과 전해 Cr 도금층 사이의 밀착력 향상을 위한 방법에 대한 연구를 하였다. 밀착력 향상을 위한 요소로 전처리 용액과 열처리 시간에 따른 영향을 알아보고자 하였으며, 이를 위해서 5가지의 산세 용액으로 각 시편을 산세 한 후, 6시간, 12시간, 18시간 열처리 하여 단면을 비교하여 열처리에 영향을 알아보고자 하였다. 연구 결과 산세 용액의 영향은 크게 나타나지 않았으며, 열처리 시간이 길수록 Ni-P/Cr의 확산이 더 잘 일어나 확산층이 더 넓어지면서 밀착력이 더 좋아 진 것으로 판단되어 진다.

• Journal of Technologic Dentistry
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• v.36 no.3
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• pp.171-177
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• 2014

Purpose: The dental medicine has been preparing the custom-made service to meet the requirements of the aged society, while the average span of human life is growing more and more, and the full denture is a representative of them. It is causing great concern in these atmosphere of society, and demands for it are expected to increase. The full denture is a uniform combination of denture base and artificial teeth using polymerization, and is most influenced by change of physical properties of denture base and bonding strength with artificial teeth. Methods: In this study, the samples were made of composite resin combined with occlusion surface of artificial teeth undergone mechanically surface treatment to evaluate the bonding strength of composite resin for repairing artificial teeth. The resin teeth used in this study are 3 types artificial teeth. And 3 types of composite resins are used that are various polymerization resin. The shear strength of composite resins made in various polymerization ways to resin teeth was measured to evaluate bonding strength of artificial teeth to each composite resins. Results: Surface hardness's results on Trubyte Biotone(74.58Hv), Biotone IPN(70.06Hv), Endura Posterio (64.48Hv). Results of bonding strength of artificial teeth to composite resins on ES samples(8.73Mpa), IF(4.37Mpa) and IZ(3.84Mpa). Conclusion: 1. The Trubyte Biotone(74.58Hv) was first, followed by Biotone IPN(70.06Hv), and Endura Posterio(64.48Hv) in surface hardness's results of worn sides using hardness test. 2. The ES samples(8.73Mpa) showed significant differences with IF(4.37Mpa) and IZ(3.84Mpa) (p<0.05), but not other samples(p>0.05) in results of bonding strength of artificial teeth to composite resins.

• Journal of the Korean Ceramic Society
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• v.39 no.3
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• pp.265-271
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• 2002

Density, water resistance, Raman and infrared spectroscopy were used to investigate the change of structural characteristics with the composition of phosphate galss samples made by melting method. The structural abnormality of the density and water resistance were rapidly increased and shown near the 60mol% of $P_2O_5$. This result could be explained by the structural changes owing to the strong shrinkage of glass network by the coordination of DBO(Double-Bonded Oxygen) around $Mg^{2+}$ cations. In addition, it seems that the DBOs coordinating $Mg^{2+}$ cations lose its characteristics of double bonding and resonate with other NBOs(Non-Bonding Oxygen).

• Journal of the Korean Wood Science and Technology
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• v.34 no.4
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• pp.31-36
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• 2006

This study was conducted to improve the bond strength of plywood bonded with F/U molar ratio urea-formaldehyde (UF) resins modified with the selected FGMDI prepolymer contents for various purposes. The amount of FGMDI was mixed with liquid UF resin at 0 wt% (as control), 2 wt%, 5 wt%, 10 wt%, 25 wt%, and 50 wt% based on the resin solids. As results, in bonding strength, plywood with F/U molar ratio of 1.4 showed the highest value in Type 2 test and all molar ratio UF resins modified with over 25 wt% of the FGMDI showed more than $11kgf/cm^2$, which was satisfied the minimum requirement of KS standard, $7.5kgf/cm^2$, after Type1.5 testing. As F/U molar ratio was increased and the FGMDI addition in the UF resin was increased, average reduction rate of Type 1.5 bonding strength compared with Type 2 was significantly decreased.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.2
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• pp.35-41
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• 2012

In this study, wheat starch adhesive was investigated the shape and structure of starch, the difference in characteristics such as chemical composition according to the fermenting period of 2 years or less. The fermenting period of wheat starch adhesive is 1 month, 2months, 4 months,6 months, 1 year, 2years old. The wheat starch adhesives were investigated total sugar contents, protein contents, properties of gelatinization, pH, the bonding strength and also observed the surface of starch,. As a result, the longer the fermenting period, the increasing in total sugar contents and decreasing in protein contents. The particle shape and surface were similar regardless of the period. In addition, properties of gelatinization according to the fermenting period also could not see the difference. In pH of the adhesive, the longer the fermenting period, the near to neutral. The adhesive was high bonding strength in 4 months, but appeared a tendency to decrease from 6 months. The damage assessment through the UV degradation in regard to the papers applied the adhesive was accomplished. Color difference was no change except 1 month. The 4 months and 6 months' pH was each 5.0, 5.2. But it was near to neutral that the 12 months and 24 months' pH was each 5.7, 5.9.

• Restorative Dentistry and Endodontics
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• v.17 no.2
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• pp.383-397
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• 1992

The purpose of this study was to evaluate the influence of artificial saliva contamination on bonding of several dentin adhesives to dentin. Sixty - three human molar teeth extracted within a month were used. Each tooth was sectioned longitudinally in a buccolingual direction to obtain 126 specimens. These specimens were randomly divided into three groups and were treated by Scotchbond 2, Gluma and All bond. Each group was subdivided into three subgroups; normal group not contaminated with artificial saliva, contaminated with artificial saliva and dried group, and contaminated with artificial saliva and washed and dried group. Enamel/dentin bonding agent(Dental Adhesive of Scotchbond 2) was applied and light cured on the treated dentin surfaces. Thereafter P - 50 were cured on them, and specimens were stored in $37^{\circ}C$ artificial saliva for 24 hours before measuring shear bond strength. Shear bond strengths were determined using an universal testing machine with cross head speed 1mm/min and SEM examinations were conducted to evaluate the resin - dentin interface and degree of penetrating resin string into the dentinal tubules. The following results were obtained. 1. Normal groups not contaminated with artificial saliva showed greater shear bond strength than any other group contaminated with artificial saliva(P<0.01). 2. The shear bond strengths showed no significant difference between washed groups with distilled water and not washed groups after contamination with artificial saliva(P>0.05). 3. In normal groups, the shear bond strength of A group was significantly greater than in any other group(P<0.01). 4. In Sand G groups, fractures after shear bond strength tests occured adhesively on resintooth interface in all specimens. But in A groups, fracture of the normal group occured cohesively in dentin and fracture of the contaminated groups occured adhesively and cohesively. 5. On SEM examination, the number of resin strings penetrated into dentinal tubules were the greatest in normal groups, followed by, in descending order, washed groups and not washed groups after contamination with artificial saliva.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.2
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• pp.357-364
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• 1996

The purpose of this study was to asses the shear bond strengths of 3 types of light-curing Glass Ionomer cement to dental amalgam with or without an intermediary agent. 60 amalgam adherent specimens were prepared and aged in water at $37^{\circ}C$ for 3 days. Before bonding, the amalgam surfaces were finished flat on 600-grit silicon carbide paper. 30 specimens among 60 were used for bonding in this condition, and the other 30 were covered with a thin layer of light-curing intermediary agent. Shear bond strengths were measured with universal testing machine (Instron, Model 4301) and statistically processed by ANOVA and t-test. On completion of bond test, the fracture surfaces were examined under light microscope so that the mode of bond failure could be assessed The results were as follows : 1. Bond strength of Fuji II LC group showed the hightest value and was followed by Vitremer, Vitrebond groups (p<0.05). 2. The bond strengths achieved without an intermediary agent were higher than those obtained with intermediary agent (p<0.05). 3. For the specimens bonded with intermediary agent, bond failures occured mostly at the agent-amalgam interface. So, the use of intermediary bonding agent was thought not recommendable at glass ionomer-amalgam interface.

• Restorative Dentistry and Endodontics
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• v.42 no.2
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• pp.95-104
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• 2017

Objectives: This study evaluated the influence of a multi-mode universal adhesive (MUA) containing silane (Single Bond Universal, 3M EPSE) on the bonding of resin cement to lithium disilicate. Materials and Methods: Thirty IPS e.max CAD specimens (Ivoclar Vivadent) were fabricated. The surfaces were treated as follows: Group A, adhesive that did not contain silane (ANS, Porcelain Bonding Resin, Bisco); Group B, silane (S) and ANS; Group C, hydrofluoric acid (HF), S, and ANS; Group D, MUA; Group E, HF and MUA. Dual-cure resin cement (NX3, Kerr) was applied and composite resin cylinders of 0.8 mm in diameter were placed on it before light polymerization. Bonded specimens were stored in water for 24 hours or underwent a 10,000 thermocycling process prior to microshear bond strength testing. The data were analyzed using multivariate analysis of variance (p < 0.05). Results: Bond strength varied significantly among the groups (p < 0.05), except for Groups A and D. Group C showed the highest initial bond strength ($27.1{\pm}6.9MPa$), followed by Group E, Group B, Group D, and Group A. Thermocycling significantly reduced bond strength in Groups B, C, and E (p < 0.05). Bond strength in Group C was the highest regardless of the storage conditions (p < 0.05). Conclusions: Surface treatment of lithium disilicate using HF and silane increased the bond strength of resin cement. However, after thermocycling, the silane in MUA did not help achieve durable bond strength between lithium disilicate and resin cement, even when HF was applied.

• Research in Community and Public Health Nursing
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• v.32 no.2
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• pp.220-231
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• 2021

Purpose: This study is a pseudo-experimental study of design before and after the non-equivalent control group, which was attempted to verify that the application of the ukulele to the elderly has the effects of reducing depression, improving self-efficacy, strengthening social bonding, and improving cognitive function. Methods: 46 (23 in the experimental group and 23 in the control group) participants were selected. The experimental group was provided with three sessions of a music program using eight Ukuleles for the elderly, while the control group was provided with three sessions for the elderly. IBM SPSS 25.0 was used for data analysis, and the independent t-test, 𝑥²-test, and Fisher's exact probability test were performed to verify the homogeneity of the subject's general characteristics. The effect verification after the experimental treatment was analyzed by Fisher's exact probability test, Friedman test, and Mann-Whitney U test. Results: Depression showed a statistically significant difference between the two groups (F=39.88, p<.001), self-efficacy showed a statistically significant difference between the two groups (z=-4.96, p<.001), social bonding showed a statistically significant difference between the two groups (z=-5.19, p<.001), and cognitive function showed a statistically significant difference between the two groups (z=-3.98, p<.001). Conclusion: It was found that the 'Music Program using the Ukulele' was effective in reducing depression of the elderly, improving self-efficacy, reinforcing social bonding, and improving cognitive function. We hope that the Music Program using the Ukulele can be used in the elderly nursing curriculum in the future, and we suggest it should be applied as a nursing intervention to those who are experiencing cognitive decline.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.55-66
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• 1999

The purpose of this study was to evaluate the microleakage of 5 current dentin bonding systems which are composed of 2 multi-bottle systems(Scotchbond Multi-Purpose, All Bond2) and 3 one-bottle systems(Single bond, One-Step, Prime & Bond). In this in vitro study, class V cavities were prepared on buccal and lingual surfaces of sixty extracted human premolars and molars on cementum margin. The experimental teeth were randomly divided into six groups of 10 samples (20 surfaces) each, Group 1 : Scotchbond Multi-Purpose ; Group 2 : All Bond 2 ; Group 3 : Single Bond ; Group 4 : One-Step ; Group 5 : Prime & Bond ; Group 6 : no bonding agent(control). The bonding agent and composite resin were applied for each group following the manufacturer's instructions. After 500 thermocycling between $5^{\circ}C$ and $55^{\circ}C$, the 60 teeth were placed in 2% Methylene blue dye for 24 hours, then rinsed with tab water. The specimen were embedded in clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimen were then observed with a stereomicroscope at ${\times}20$. The results of study were statistically analyzed using the Student-Newmann-Keul's Methods and the Mann-Whitney Rank Sum Test. The resin/dentin interfaces were examined under Scanning Electron Microscopy. The results of this study were as follows. 1. None of the dentin bonding systems used in this study showed significant difference in leakage values at both the enamel and the dentin margins (P>0.05). 2. In all groups except the control, leakage value seen at the enamel margin was significantly lower than that seen at the dentin margin (P<0.05). 3. Compared to the control group, all the groups treated with dentin bonding systems showed significantly lower leakage value at both enamel and dentin margins (P<0.05). 4. In the SEM view, gaps were observed in the composite resin / dentin interface in group 6 where no dentin bonding agent was used, and in all the other groups (group 1, 2, 3, 4, 5) composite resin, hybrid layer, and dentin were seen to be closely adhering to each other where there were no leakages. Well-developed resin tags 3~100${\mu}m$ in length infiltrated dentinal tubules past the hybrid layer and a hybrid layer 1~5${\mu}m$ thick had developed between the dentinal surface and the composite resin surface.