• Composites Research
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• v.24 no.1
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• pp.31-36
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• 2011

Adhesive shear strengths of the established adhesives and the alternative adhesives were evaluated and their chemical structures were analyzed in order to investigate the possibility of replacing the established adhesives with the alternative adhesives applicable to the seeker for the guided missiles. Two types of the adhesives such as the structural adhesives and the sealant adhesives were considered. Those adhesives were exposed to the combined environmental factors consisting of temperature, moisture and ultraviolet over 1000 hours. Adhesive shear test was conducted to evaluate adhesive shear strengths and ATR FT-IR was utilized to investigate chemical structures. According to the results, the adhesive shear strengths of the alternative adhesives revealed higher than those of the established adhesives. Also the alternative adhesives were more stable to the combined environmental condition than the established adhesives. Therefore, it is found that the established adhesives were able to be replaced by the alternative adhesives.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.7
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• pp.455-463
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• 2022

As the need for R&D for high reliability cameras, such as satellite cameras, increases, the reliability of the bonding strength properties between an opto-mechanical structure and an optical component has been secured through specimen tests. However, the widely used specimen shape is not suitable for the application of glass and glass-ceramic material, which is fragile, making it difficult to obtain accurate bonding properties due to stress concentration in glass parts before reaching the bonding strength limit. In this study, the stress distribution characteristics in the shear test condition for various specimen shapes were studied analytically, based on the test results of the glass material's own fracture. Through this, the shape characteristics capable of relieving the stress concentration of the glass part were derived, and the range of the bonding shear strength verifiable by the specimen test was improved.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.40-47
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• 2006

Optical performance of the mirror for satellite camera is highly dependent on the adhesive properties of its support. Therefore, in this paper, the adhesive properties of three kinds of space adhesives are investigated. For this purpose, the lap shear test is performed with Zerodur-to-metal lap shear specimen as well as metal-to-metal one. And it is also investigated whether reliable adhesive strength can be secured after the specific thermal cycle. Finally, the properties of three adhesives are compared with each other.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.1
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• pp.25-32
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• 2016

The purpose of this study is to evaluate the performance on the compressive bonding shear strength of ultra-high strength steel fiber reinforced cementitous composites(UHSCC). As a result of compressive bonding shear strength through Direct shear test, It was found that the specimen($150{\times}150{\times}150mm$) of NC(Normal concrete) + NC showed similar compressive bonding shear strength at whole experimental level. On the other hand, the specimen of UHSCC + UHSCC showed decrease of compressive bonding shear strength from after 30 minutes of the retarded placement than 0 minute. As a result of analyzing failure mode of bonding interface, It was found that the specimen of NC + NC showed mixed failure at whole experimental level. In case of the specimen of UHSCC + UHSCC, it showed interface failure from the specimen that are 30 minutes, 60 minutes and 90 minutes of delay of concrete placing. As a result of analyzing XRD test in terms of the placement interface on the specimen of NC and UHSCC, relatively much amount of $SiO_2$ was detected from the specimen of UHSCC than that of NC. It is judged that the most of main components of coating film shown in the specimen of UHSCC is $SiO_2$. In conclusion, it is judged that UHSCC which is made from after 30 minutes of delay of concrete placing is unable to be used as structural member because of deterioration of bonding performance. From later study, it is judged that the improvement of bonding performance from the part of cold joint occurrence is necessary through the interface preparation method.

• Composites Research
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• v.15 no.5
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• pp.19-26
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• 2002

Real defects in composite structures were detected by using laser measuring system. Four types of real defects, that is, impact-induced delamination in a composite laminate, debond in a honeycomb structure, free-edge delamination in a composite laminate and debond in an adhesive joint, were made by applying several types of loads to the specimens. Laser measuring system such as ESPI and shearography technique were used to detect those defects. Thermal loading method, which can easily induce the surface deformation of specimen, was used to detect the defects. Experimental results show that the defects in composite structures could be easily detected by ESPI and shearography technique. Moreover, it shows that ESPI and shearography technique could be usefully applied to the detection of defects in various kinds of composite structures.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.127-133
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• 2020

It is important to measure the quantitative adhesive strength between an organic adhesive and a metal adherend. In measuring the adhesive strength between an organic adhesive and a metal adherend, the effect of the kind and thickness of the adherend on the adhesive strength was studied. Two kinds of metal adherends were selected, aluminum (Al1050) and stainless steel (STS304), and a dolly test and a lap shear test were used to measure the adhesive strength. When measuring the adhesive strength between the organic adhesive and the metal adherend by the tensile stress mode of dolly test, the change in the thickness of the metal adherend had little effect on the adhesive strength, however, the adhesive strength was different depending on the kind of the adherend. On the other hand, when measuring the adhesive strength between the organic adhesive and the metal adherend by the lap shear test, the change in the relative thickness of the metal adherend had an effect on the adhesive strength. The reason is that the bending phenomenon of the adherend occurring in the edge of bonding region during the lap shear test contributes to lowering the adhesive strength by generating additional tensile stress in the bonding region. From this work, it is concluded that the dolly test could be widely used when measuring the quantitative adhesive strength of organic adhesives and metal adherend because there is little change in adhesive strength even though the thickness of the adherend is changed.

• Composites Research
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• v.17 no.4
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• pp.40-46
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• 2004

A single lap shear test was used to investigate the effects of the ratio of a catalyst to a self-healing agent and curing temperature on the bond performance of autonomic polymer composites. DCPD (dicyclopentadiene), ENB (5-ethylidene-2-norbornene), and their mixture were used as self-healing agents and bis(triclohexylphosphine) benzyllidine ruthenium (IV) dichloride Grubbs' catalyst was used as a catalyst. During the experiments, the catalyst ratios of 1.0wt% and 0.5wt% were applied to DCPD, the catalyst ratio of 0.lwt% was applied to ENB, and the catalyst ratio of 0.5wt% was applied to the mixtutes of DPCD and ENB. In addition, the curing temperatures of $25^{\circ}C$, $60{\circ}C$, and $80^{\circ}C$ were considered. According to the results, the higher catalyst ratio and the longer curing time were required to obtain more stabilized bond shear strength of DCPD. ENB with a lower catalyst ratio was cured faster than DCPD. Unlike DCPD, ENB stabilized after a steady fall from its peak as the curing time increased. Moreover, the mixtures of DCPD and ENB revealed similar curing behavior to ENB, but the increase in mixture ratio of ENB to DCPD caused curing process to be faster. Also the increase in curing temperature caused the bond shear strength to be higher and the curing time to be quicker.

• Journal of the Korean Wood Science and Technology
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• v.45 no.3
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• pp.243-249
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• 2017

This study was performed to find out the optimum adhesive conditions on manufacturing a cross-laminated timber (hereinafter CLT) with using domestic Korean Pine (Pinus koraiensis). The adhesive conditions including a applied amount of the glue and a Pressure are the one of the most important key factors on establishing CLT production process. The shear strength was examined with differing the adhesive conditions while using Phenol Resorcinol Formaldehyde Resin Adhesive (PRF resin). The optimum adhesive conditions was confirmed to be: glue spread of $250g/m^2$ and Pressure of 0.8 MPa respectively. The grain directions of glued specimens were also considered, perpendicularly bonded and parallelly bonded groups. Shear strength of the former group showed lower values than the latter group which is considered to be the effect of a rolling shear. Meanwhile the shear strength of both group satisfied the Korean Standard (KS F 3021) and the European Standard (EN 14080 and EN 16351). The results derived from this study can be used as the basic data for manufacturing the CLT with domestic Korean Pine. And additional researches for the other species including domestic Korean Larch and Pitch Pine is also now being performed.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.233-244
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• 1996

The purpose of this study was to compare the shear bond strength obtained from ceramic and plastic brackets bonded with various light-cured adhesives and to evaluate their debonded failure sites. Plastic brackets, Transcend 6000, Signature and Starflre TMB brackets were bonded with Orthobond, Light Bond and Transbond on one hundred forty extracted human premolar teeth as manufacturer's descriptions. After thermocycling the brackets were debonded with an Instron universal testing machine and the debonded bracket base surfaces were inspected under stereoscope to evaluate the failure sites. Also the shear bond strength and failure patterns with different curing time and with two different source of light were compared. The results were as follows. 1. There were no statistically significant differences among the mean shear bond strength of Orthobond, Light Bond and Transbond in a same bracket group except Plastic bracket group(p<0.05). 2. The mean shear bond strength of each adhesive with different bracket groups showed statistically significant differences. Stafire TMB showed the highest shear bond strenght among the brackets in this study, but there was no statistically singnificant difference with Transcend 6000 while there was statistically significant difference with Signature.(p<0.05) 3. The various bonding failure patterns were occurred among different bracket groups but most of failure sites were bracket base -adhesive interfaces. 4. There were no statistically significant differences in shear bond strength between the groups with curing time of 10 second and 20 second, and between the groups with two different sources of light as long as sufficient light intensity(above $400mWcm^2$) were provided(p<0.05). According to the result, it should be considered in clinical use of ceramic bracket with light-cured adhesives that the shear strengths of ceramic brackets were influenced by the retention from of bracket base as well as the composition of bracket and there was no difference in the shear bond strenght among various light-cured adhesives used in this study.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.56.2-56.2
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• 2011

최근 철강, 알루미늄, 이종재료의 접합 등 용접이 어려운 부분에 구조용 접착제의 적용이 증가하고 있는 추세이다. 이를 위해 변성 에폭시레진을 활용한 고접합 강도, 고인성의 구조용 접착제가 연구되어 지고 있다. 피착제의 표면처리는 접합부의 접합강도를 향상시키는 방법으로 알려져 있으나 최근의 구조용 접착제는 표면 전처리 없이도 우수한 접착 특성을 보이는 것으로 기대되고 있다. 본 연구에서는 변성레진에 대해서 각종 표면처리가 접합부 특성에 미치는 영향을 조사하였다. 피착제로는 자동차용 냉연강판인 SPRC440을 사용하였고, 전처리로는 무처리 상태, SiC연마지를 이용한 연마, 아르곤 및 산소가스를 이용한 마이크로웨이브 플라즈마 표면처리, 산세 등의 표면처리를 실시하였다. 에폭시 접착제는 변성 에폭시 레진과 경화제 및 촉매제를 이용하여 직접 포뮬레이션하였다. 단일 겹치기 전단강도 시험과 T-Peel 시험은 각각 ASTM D 1002 규격에 따라 준비하였으며 인장 시험 후 파면은 SEM으로 관찰하였다.