1,721,036 research outputs found
The effects of surface roughness and bond thickness on the fatigue life of adhesively bonded tubular single lap joints
No full textSince the surface roughness of adherends greatly affects the strength of adhesively bonded joints, the effect of surface roughness on the fatigue life of adhesively bonded tubular single lap joints was investigated analytically and experimentally by a fatigue torsion test. The stiffness of the interfacial layer between the adherends and the adhesive was modelled as a normal statistical distribution function of the surface roughness of the adherends. From the investigation, it was found that the optimum surface roughness of the adherends for the fatigue strength of tubular single lap joints was dependent on the bond thickness and applied load
Hygrothermal effects on the strength of adhesively bonded joints
No full textThe strength of adhesively bonded joints degrades when the joints are exposed to a high temperature or high humidity environment because of the degradation of the adhesive. In this paper, the strength and modulus of adhesives under hygrothermal environments were measured with respect to the absorbed moisture content and temperature. Then the strength of adhesively bonded tubular lap joints was investigated with respect to the absorbed moisture content. From the investigation it was found that the strength of the adhesives decreased as the absorbed moisture content increased, but the strength of the adhesively bonded tubular lap joints decreased less compared with that of the adhesives, due to the moisture swelling effect. Also, it was found that chemical surface treatments of the adherends improved the strength retention of the joint under a hygrothermal environment
A Microcalcification Detection Using Multi-Layer Support Vector Machine in Korean Digital Mammogram
Full text linkA computer-aided diagnosis (CAD) system has
been examined to reduce the effort of radiologist. In the
mammogram, it is helpful to improve the diagnostic accuracy
of malignancy microcalcifications in early stage of detecting
breast cancer. In this paper, we propose a microcalcification
detection method using multi-layer support vector machine
(SVM) classifiers to determine whether microcalcifications are
malignant or benign tumors. The proposed microcalcification
detection is divided into two steps, each of which uses a SVM
classifier. First, potential ROIs (Region of interest) those are
suspicious as malignant tumors are detected as a coarse detection
level. And then, each ROI is classified whether it is malignant
or not. The proposed algorithm is applied to the Korean
digital mammogram. Experimental result showed that the
proposed method would outperform conventional method
using ANN (artificial neural networks).This paper is supported by the development of digital
CAD system project (02-PJ3-PG6-EV06-0002) of Ministry
of Health and Welfare in The Republic of Korea.전기및전자공학
Measurement of the degree of cure of glass fiber-epoxy composites using dielectrometry
No full textCure monitoring of thermosetting resin matrix composites during the molding process of polymer matrix composites is important for the quality control and reliable manufacturing of composite products. Since dielectrometry can in situ measure the cure status during the actual curing process of polymer matrix composites, it is being widely employed as cure monitoring apparatus. Although dielectrometry is more convenient in measuring the cure status of resin than differential scanning calorimetry (DSC), the former requires complicated calculation to yield the cure information from the dissipation factor of the resin because the measured dissipation factor of the resin by dielectrometry contains viscosity information rather than the degree of cure of the resin. In this paper, the dissipation factor of glass fiber-epoxy composite was measured using developed dielectrometry sensors and an electrical circuit. Then the isothermal degree of cure was calculated and compared with that obtained from DSC experiments. (C) 2001 Elsevier Science B.V. All rights reserved
Repair of underground buried pipes with resin transfer molding
No full textRepairing and replacing of worn-out underground pipes, such as sewer pipes, water-supply pipes, gas pipes, and communication cables by excavating not only cause traffic congestion but also produce large amount of waste. Also, the operation requires heavy equipments and longer operating time and high cost. In this study, the repairing-reinforcing process of underground pipes with glass fiber fabric polymer composites using resin transfer molding (RTM) which overcomes the problems of present trenchless technologies has been developed. The developed process requires shorter operation time and lower cost with smaller and simpler operating equipments than conventional trenchless technologies. For the faultless operation. a simple method to apply pressure and vacuum to the reinforcement was developed. The resin wetting and void removal during RTM process for very large and long-composite buried pipes were experimentally investigated, and the efficient void removal method was suggested. Cure status and resin filling were monitored with a commercial di-electrometry cure monitoring system, LACOMCURE. From the investigation, it has been found that the developed repair technology with appropriate process parameters and on-line cure monitoring has many advantages over conventional methods. (C) 2002 Published by Elsevier Science Ltd
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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