• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.389-398
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• 2008

The purpose of this study was to evaluate the effects of collagenase and esterase on dentin bond strength and nanoleakage. Resin composites were bonded to occlusal dentin of premolars with Single Bond 2(SB) and Clearfil SE Bond(SE). After the microtensile specimens were prepared and stored in PBS for 24 hours(I) or, PBS(II), collagenase(III), esterase(IV) solution for 4 weeks, the specimens were stained with silver nitrate solution. Microtensile bond strength(${\mu}TBS$) and silver penetration area were measured and, the results were as follows: 1. For group II, III, and IV, the bond strengths of SB were lower than those of SB(p<0.05). The bond strengths of SB II, III, and IV were lower than that of SB I(p<0.05). There was no difference among the bond strengths of SE $I{\sim}IV$ groups(p>0.05). 2. Silver penetration areas of SB were higher than those of SE for all storage groups(p<0.05). In SB and SE groups, there was no significant difference of silver penetration area among $I{\sim}IV$ groups(p>0.05). 3. SE I, II, and III showed inverse relationship between the bond strengths and the silver penetration areas(p<0.05).

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.1
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• pp.57-65
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• 2023

A vibration response-based detection system was used to investigate the adhesive areas of single-lap joints using a nonlinear transformation approach for deep learning. In industry or engineering fields, it is difficult to know the condition of an invisible part within a structure that cannot easily be disassembled and the conditions of adhesive areas of adhesively bonded structures. To address these issues, a detection method was devised that uses nonlinear transformation to determine the adhesive areas of various single-lap-jointed specimens from the vibration response of the reference specimen. In this study, a frequency response function with nonlinear transformation was employed to identify the vibration characteristics, and a virtual spectrogram was used for classification in convolutional neural network based deep learning. Moreover, a vibration experiment, an analytical solution, and a finite-element analysis were performed to verify the developed method with aluminum, carbon fiber composite, and ultra-high-molecular-weight polyethylene specimens.

• Journal of the Korean Wood Science and Technology
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• v.38 no.1
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• pp.11-16
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• 2010

Unlike other composites boards such as fiberboard and particleboard, plywood is manufactured with sheets of veneers. When the plywood manufactured, the adhesive is spreaded through gluelines on each surface of veneers. For that reason, formaldehyde emission of plywood can be considered as different way. Therefore, this research was conducted to understand the formaldehyde emission pattern of plywood. To measure formaldehyde emission, four different specimen preparing methods were used. The test specimen taken by a total surface area, a given number and a total side area showed inconsistent results. On the other hand, the result of formaldehyde emission showed consistency when considered only the length of adhesive layers.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.139-139
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• 2013

본 발표에서는 3차원 안테나 유도 방식(3DAI)의 대기압 플라즈마 발생기술을 소개하고 그 응용에 대해 논의하고자 한다. 3DAI (3 Dimensional Antenna Induced) 방식의 가장 큰 특징은 하나의 전원 장치로 아크 발생 없이 다수의 금속 전극에서 플라즈마를 발생 할 수 있다는 특징과 3차원과 같은 높이 100 mm 이상의 큰 volume에서 플라즈마를 발생할 수 있는 기술로 그 적용을 확대할 수 있을 것으로 기대되는 기술이다. 다수의 금속 전극에서 플라즈마를 발생 시키는 기술은 대면적 처리가 가능하다는 의미이며 금속 전극을 사용한다는 것은 반 영구적 전극 사용을 할 수 있다는 의미로 해석할 수 있다. 본 연구에서는 신발 접착에 필요한 플라즈마 처리면적 350 mm, 플라즈마 발생 높이 100 mm급 3DAI 대기압 플라즈마 발생 장치를 개발하였다. 개발된 3DAI 플라즈마 기술을 이용하여 신발 재료 접착에 적용하였다. 화학 약품인 프라이머를 사용하지 않고 수성접착제를 사용하여 밑창인 고무와 중창인 IP 및 PU 등에서 모두 초기 접착 강도 1.5 kg/cm 이상, 경시 접착강도 3.5 kg/cm 이상으로 모재가 대부분 파괴되는 접착 강도를 얻었으며, 접착 수율이 99.9% 이상의 높은 생산성을 보여주고 있다.

• The korean journal of orthodontics
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• v.32 no.2 s.91
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• pp.143-153
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• 2002

The bonded orthodontic retainer constructed from composite and multistrand orthodontic wire provides an esthetic and efficient system for maintained retention. This study was designed to measure shear bond strength of bonded retainers and to suggest a optimal combination of a multistrand wire and bonding method used when bonded retainer was fabricated. 160 sound maxillary and mandibular premolars were used for 80 test samples. After Uniformizing bonding area, length of wire, and thickness of composite, multistrand wire was bonded to fabricated a bonded retainer by direct or indirect bonding method. Shear bond strength and extension length of each sample were measured by a universal testing machine. The results of this study were as follows : 1. In vitro shear bond testing found 6-stranded, 0.0155 inch wires to have the largest shear bond strength and 3-stranded, 0.0195 inch wires to have the least shear bond strength. But, These difference was not statistically significant(p<0.05). 2. In vitro extension testing found 3-stranded, 0.0155 inch wires to have the largest extension length and 3-stranded, 0.0195 inch wires to have the least extension length(p<0.05). The larger diameter wire was used, the larger extension length was shown. But, the strand of wire is not related to the extension length of wire. 3. In comparison with direct bonding method, larger shear bond strength and extension length was shown in indirect bonding method(p<0.05).

• Composites Research
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• v.31 no.4
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• pp.151-155
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• 2018

Mechanical joint and adhesive joint are two typical joining methods for structures. The adhesive joints distribute the load over a larger area than mechanical joints and have excellent fatigue properties. However, the strength of adhesive joint greatly depends on the environmental conditions and the skill of the operator. Therefore, there is a need for techniques to evaluate the quality of the adhesive joints. The electric resistance method is a very promising technique for detecting defects by measuring the electrical resistance of an adhesive joint in which CNTs are dispersed in an adhesive. In this study, Aluminium-Aluminium adhesive single lap joint specimens were fabricated by using the adhesive dispersing CNTs using a sonicator and a 3-roll mill, and the static strengths and defect detection capabilities of the joints using the electrical resistance method were evaluated according to the CNTs content.

• The korean journal of orthodontics
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• v.31 no.3 s.86
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• pp.381-391
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• 2001

In orthodontic patients, frequently, amalgam restorations are present on the buccal surface of molars. The ability to successfully bond orthodontic brackets and buccal tubes to amalgam restorations would therefore be of clinical value. But the bond strength to total amalgam surface is probably not critical in most instances. Because there is usually a considerable amount of sound enamel surrounding a buccal amalgam filling. The purpose of this study was to evaluate the bond strengths of orthodontic brackets according to surface treatments and size of amalgam restorations. Eighty tooth specimen were assigned to four groups according to amalgam size-1.5mm, 2.0mm, 2.5mm, 3.0mm diameter-and then divided into two groups : one half was sandblasting group the other half was no sandblasting group. After Bracket bonding, shear bond strength for each specimen was determined and bond failure patterns was evaluated. 1. Shear bond strength of amalgam size 1.5mm group was significantly higher than that of the other groups. (p<0.05) 2. There was no significant difference in the bond strength produced by sandblasting. (p<0.05) 3. Shear bond strength of G and H group of which amalgam restoration ratio to the bracket base sizes were $61\%$ were significantly decreased $50-60\% level of that of control group. (p<0.05) 4. There was positive correlation between sandblasting and mARI. (p<0.05) The results of the present study indicate that it may be feasible to bond orthodontic bracket clinically successfully to amalgam restoration with conventional orthodontic resin when its size is less than $50\%$ of that of bracket base.

• Restorative Dentistry and Endodontics
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• v.33 no.5
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• pp.443-451
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• 2008

The purpose of this study was to evaluate the effect of additional etching procedure prior to Maxcem resin cement application in indirect restoration cementation using push-out bonding strength. One hundred and two extracted human molars were used to make indirect resin restorations of gold inlay and Synfony. These restorations were cemented using Maxcem and Variolink II. Additional etching procedures were done for one group with Maxcem. Three groups have 17 specimens in both restoration types. Push-out bond strength was measured using multi-purpose tester and calculated for bonding strength per sqaure-millimeter area. The mean bonding strength values were compared using SPSS 12.0K program for one-way ANOVA and Scheffe's Test with 95% significance. Under the condition of this study, the additional etching procedure prior to usage of Maxcem resulted in reduced bond strength for both of restoration types.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.27-32
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• 2009

The main objective of this study is to develop a test for measuring the bond shear strength between pavement layers. The research is also conducted to evaluate tack coat materials and application rate in porous pavement. The experiment includes using two types of emulsions (RSC-4, Modified Emulsion) and a asphalt binder type (HM-1). HM-1 was developed to be applied in porous pavement. The bond shear strengths were measured by a direct shear type device under various test conditions. The shear strength may not be appropriate in the evaluation of the bond shear strength, while the toughness of the test may be useful. In case of the tack coat application rate in porous pavement, RSC-4 has to be used a minimum amount of $0.8l/m^2$ and modified emulsion asphalt has to be applied a volume of use $0.5{\sim}0.6l/m^2$. HM-1, asphalt cement type, is far stronger bond shear strength than emulsified asphalt tack coat and had showed the excellent trackless property.

• Polymer(Korea)
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• v.27 no.4
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• pp.275-284
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• 2003

The positive temperature coefficient (PTC) effects of high density polyethylene (HDPE)/carbon black composite materials were investigated by enhancing adhesive characteristics of electrodes and controlling HDPE chemical crosslinking. When the silver paste was used as an electrode for the same 45 wt% HDPE/carbon composites, the resistance was over 1 $\Omega$, which should be compared with the resistance of 0.2 $\Omega$ for the dendritic copper electrode. In general, the silver-paste electrode exhibited higher electrical resistance than cupper electrode due to the interfacial resistance between the electrode and PTC composites. The HDPE/carbon composite exhibited typical PTC characteristics maintaining a constant resistance up to vicat point and showing a maximum at the melting point of HDPE. The crosslinked HDPE significantly decreased the negative temperature coefficient (NTC) phenomena, and desirably showed a constant or slightly increasing feature of electrical resistance in the high temperature region.