• Journal of Adhesion and Interface
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• v.7 no.4
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• pp.10-12
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• 2006

The successful use of adhesively bonded parts depends on the defect-free bond of the components. Therefore it is necessary to detect relevant faults and defects in an early state of the production. A 100% test should be pursued, but especially at complicated structures the detection of defects is not easy. Possible testing methods, which show a high potential for the NDT of adhesively bonded parts, are thermography based NDT methods. At present mainly two different procedures of active thermography are being used: Pulse and Lock-In Thermography. With pulse thermography the examined material is warmed up with a short energy pulse (light, eddy current or ultrasonic pulse) and the heat response is recorded after a certain time. The result is an infrared image which indicates material defects in different depths. This paper presents a variety of images showing the capability of Lock-In Thermography to image subsurface defects. Several examples of adhesives joints qualify the ultrasonic Lock-In-Thermography for the in-process quality control for adhesive bonded components.

• Elastomers and Composites
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• v.35 no.4
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• pp.296-302
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• 2000

The surfaces of injection and pressure-molded sheets of poly(ethylene-covulylacetate)(EVA) foams used for shoe mid-sole were treated with low temperature plasma to improve adhesion with a water-based polyurethane adhesives. Several experimental variables were considered, such as radio frequency power, treating time, type of gas. gas flow, and distance between electrode and sample. The modificated surface by plasma treatment were characterized using contact angle meter, scanning electron microscopy(SEM), universal testing machine(UTM). Adhesion was tested by T-peel tests of treated EVA foams/polyurethane adhesive joints. The treatment in the low temperature plasma produced a noticeable decrease in contact angle. The peel strength of EVA foams treated with plasma was increased with plasma treating time, and gas flow.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.267-278
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• 2010

To improve the grout penetration characteristics, vibration method was adopted in this study. The grout material perturbed by cyclic vibration is injected into the ground. By applying the vibrating flow system, cement particles will become less adhesive and the clogging tendency will be decreased. A series of pilot-scale chamber tests were performed to verify the enhancement of the groutability by applying the vibratory grout injection; assessment on change of the lumped parameter $\theta$ which represents a barometer of clogging phenomenon was made. Moreover, the effect of vibratory grout injection through the joint was also investigated using artificially made rock joints. Experimental results as well as analytical results show that the grout penetration depth can be substantially improved by vibration grouting. Moreover, it was found that enhancement of the permeation grouting due to vibratory injection is more dominant at low grouting pressure of less than 400kPa.

• Journal of the Korea Furniture Society
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• v.10 no.2
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• pp.73-78
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• 1999

This paper describes the relationship between the bending strength properties of sloped finger-jointed woods and the acoustic emissions(AEs) generated during the test. Rhus verniciflua pieces were cut in sloped-finger types and glued with three kinds of adhesives(polyvinyl acetate, polyvinyl-acryl acetate and oilic urethane resin). The slope ratios of finger joints were 0, 1.0, 1.5, and 2.0. The AE cumulative event count and cumulative count were measured during the bending test. The results were as follows: The lower the bending strength(load) was, the generation time of AE event count got and the higher the increasing rate of AE event count became in the sloped finger-jointed specimens bonded with polyvinyl acetate, polyvinyl-acryl acetate oilic urethane resin adhesives. Therefore, the slope from load-AE cumulative event count was very steep. The patterns of AE event count and count were very similar. The relationship between the MOR and the AE parameter from load and AE cumulatve event count in the early stage of the sloped finger-jointed specimens bonded with polyvinyl acetate, polyvinyl-acryl and oilic urethane resin adhesives was much greater than that between the MOE and the MOR. Therefore, the AE signals obtained during bending test are useful for estimating the strength of sloped finger-jointed Rhus verniciflua specimens.

• Journal of Welding and Joining
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• v.21 no.5
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• pp.555-560
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• 2003

In automobile industry, it is necessary to reduce the weight from the view point of energy and environmental problems in these days. One of the ways for weight reduction is using adhesive aluminum structures. In this study, ultrasonic signals reflected from the adhesively bonded joint layer are used to evaluate the adhesively bonded joints. FFT is performed to determine bond-layer parameters such as effective thickness and frequency for adhesively bonded joint Al 6061 plates in comparison with the measured and theoretical ratios. And the parameters of ultrasonic wave and the J-integral are investigated to evaluate the adhesively bonded joint strength by DCB specimens.

• Current Photovoltaic Research
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• v.5 no.3
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• pp.83-88
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• 2017

The growth of intermetallic compounds is an important factor in the reliability of solar cells. Especially, the temperature change in the soldering process greatly affects the thickness of the intermetallic compound layer. In this study, we investigated the intermetallic compound growth by Sn-diffusion in solder joints of solar cells. The thickness of the intermetallic compound layer was analyzed by IR lamp power and hot plate temperature control, and the correlation between the intermetallic compound layer and the adhesive strength was confirmed by a $90^{\circ}$ peel test. In order to investigate the growth of the intermetallic compound layer during isothermal aging, the growth of the intermetallic compound layer was analyzed at $85^{\circ}C$ and 85% for 500 h. In addition, the activation energy of Sn was calculated. The diffusion coefficient of the intermetallic compound layer was simulated and compared with experimental results to predict the long-term reliability.

• Journal of Welding and Joining
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• v.35 no.3
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• pp.15-20
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• 2017

In this paper, two types of assemblies using CNT-filled SACAs (with 0.03 wt% CNTs and without CNT) were prepared to investigate the influence of carbon nanotubes (CNTs) on the reliability properties of solderable anisotropic conductive adhesives (SACAs) with a low-melting-point alloy (LMPA). Two types of reliability test including thermal shock (TS: -55 to $125^{\circ}C$, 1000 cycles) and high-temperature and high-humidity (HTHH: $85^{\circ}C$, 85% RH, 1000 h) tests were conducted. The SACA assemblies with and without CNTs showed stable electrical reliability properties due to the formation of wide and stable metallurgical interconnection between corresponding metallizations by the molten LMPA fillers. Although the mechanical pull strength of CNT-filled SACA assemblies was decreased after thermal aging (because of the excessive layer growth and planarization of the IMCs), the CNT-filled SACA with 0.03wt% CNTs showed enhanced mechanical reliability properties compared with the SACA assemblies no CNTs. This enhancement in mechanical performance was due to the reinforcement effect of the CNTs. These results demonstrate that CNTs within the CNT-filled SACAs can improve the reliability properties of CNT-filled SACAs joints due to their superior physical properties.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.1-6
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• 2011

New methods for joining sheet of metal are being sought. One of the most promising methods is MPJ (mechanical press joining). It has been used in thin metal work because of its simple process and relative advantages over other methods, as it requires no fasteners such as bolts or rivets, consumes less energy than welding, and produces less ecological problems than adhesive methods. In this study, the joining process and static behavior of single overlap joints has been investigated. During fixed die type joining process for SPCC plates, the optimal applied punching force was found. The maximum tensile-shear strength of the specimen produced at the optimal punching force was 1.75 kN. The FEM analysis result on the tensile-shear specimen showed the maximum von-Mises stress of 373 MPa under the applied load of 1.7 kN, which is very close to the maximum tensile strength of the SPCC sheet(= 382 MPa). This suggests that the FEM analysis is capable of predicting the maximum tensile load of the joint.

• Korean Journal of Metals and Materials
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• v.47 no.7
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• pp.447-453
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• 2009

Isotropic conductive adhesives (ICAs) have been used or considered as an interconnect material for radio frequency identification (RFID) inlays or other flip chip assemblies due to the advantages of having a low temperature and high-speed bonding. In this work, the curing properties of commercial ICAs for the RFID tag application and the signal transmission in conductive lines that contained the ICA joints were evaluated as a function of the degree of cure at 900 MHz frequency range. The ICAs showed adequate signal transmission only after the curing process passed over the critical time. It was also found that the insertion loss of signal was more dependent on the contact states of Ag fillers in the bondline in preference to the electrical resistance of the ICA itself.

• Journal of the Korea Institute of Building Construction
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• v.21 no.1
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• pp.87-95
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• 2021

In this study, seven companies(A~G) designated as new construction technology selected and evaluated KS F 2622: Method of test for performance evaluation of membrane roofing systems that are similar to field application conditions. As a result of the test, it was confirmed that although all test specimens exceeded KS standards in the basic physical, it was difficult to obtain field quality performance in weak areas such as joints and vertical parts of the adhesive coating method in water-tightness, sagging resistance, swelling resistance tests except for fatigue(crack behavior) tests.