• Corrosion Science and Technology
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• v.15 no.2
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• pp.58-68
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• 2016

Many industries need the universal standard or technique to obtain the identical CCT regardless of specimen geometries. This study aimed to determine an appropriate applied torque to the cylindrical specimen defining the apparatus and the procedure to measure the temperature of initiating crevice corrosion in tubular shape products such as pipes, tubes and round rods etc; the test method also proved applicable to the plate type specimen. A series of experiments for CCT measurements with the plate type and cylindrical stainless steel specimens of various diameters with different microstructures (austenitic and duplex) and PRENs were conducted to determine the relationship among geometries on CCT. Thus, the apparatus that could measure the CCT of stainless steels with both plate and cylindrical geometries was newly designed. The use of the apparatus facilitated the same CCT value for both geometries only if the specimens were made of the same alloy. The applied torque can be calculated for various diameters of the cylindrical specimens using the following relation; Applied torque, $Nm=-0.0012D^2+0.019D+2.4463$ (D; the diameter of cylindrical specimen, mm). However, upwards of 35 mm diameter cylindrical specimens require 1.58Nm, which is the same torque for the plate type specimen; in addition, this test method cannot be used for cylindrical specimens of less than 15 mm diameter.

• Smart Structures and Systems
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• v.26 no.5
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• pp.657-666
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• 2020

A rotational pulse-echo ultrasonic propagation imager that can inspect cylindrical specimens for material nondestructive evaluations is proposed herein. In this system, a laser-generated ultrasonic bulk wave is used for inspection, which enables a clear visualization of subsurface defects with a precise reproduction of the damage shape and size. The ultrasonic waves are generated by a Q-switched laser that impinges on the outer surface of the specimen walls. The generated waves travel through the walls and their echo is detected by a Laser Doppler Vibrometer (LDV) at the same point. To obtain the optimal Signal-to-Noise Ratio (SNR) of the measured signal, the LDV requires the sensed surface to be at a right angle to the laser beam and at a predefined constant standoff distance from the laser head. For flat specimens, these constraints can be easily satisfied by performing a raster scan using a dual-axis linear stage. However, this arrangement cannot be used for cylindrical specimens owing to their curved nature. To inspect the cylindrical specimens, a circular scan technology is newly proposed for pulse-echo laser ultrasound. A rotational stage is coupled with a single-axis linear stage to inspect the desired area of the specimen. This system arrangement ensures that the standoff distance and beam incidence angle are maintained while the cylindrical specimen is being inspected. This enables the inspection of a curved specimen while maintaining the optimal SNR. The measurement result is displayed in parallel with the on-going inspection. The inspection data used in scanning are mapped from rotational coordinates to linear coordinates for visualization and post-processing of results. A graphical user interface software is implemented in C++ using a QT framework and controls all the individual blocks of the system and implements the necessary image processing, scan calculations, data acquisition, signal processing and result visualization.

• Composites Research
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• v.30 no.6
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• pp.406-409
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• 2017

The thin-walled cylindrical tubes are frequently used for the evaluation of fatigue property of composites. But the curvature of the tubular specimen induces interlaminar normal stress which may affect the fatigue property. In this paper interlaminar normal stress effect on the fatigue behaviour of thin-walled graphite/epoxy tubes $[{\pm}45]_s$ composites was studied experimentally. It was concluded that the interlaminar normal stress induced by the curvature of the cylinder has no discernible effect on the fatigue life. But excessive internal pressure can produce the stiffness increase and this affects the fatigue life of the cylindrical tubular composite.

• Journal of the Korean Wood Science and Technology
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• v.35 no.1
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• pp.17-26
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• 2007

This study was conducted to investigate the effects of End-coating (CO) treatment and Vapor-dam (V) treatment on the air circulating oven drying characteristics of green stock (Paulownia tomentosa) for drum. The reduction of the weight of specimens was greatly displayed in order of control (C-NC) treatment, End-coating (C-CO) treatment, Vapor-dam (V-NC) treatment and Vapor-dam/End-coating (V-CO) treatment after the beginning of drying. The V-CO treated specimen showed smoother temperature gradient compared with the V-NC treated specimen throughout whole drying stage and there was little temperature gradient between the inner and outer part of the cylindrical stock. The C-CO treated specimen showed higher value of vapor pressure in both the inner and outer part of the cylindrical stock until the middle stage of drying, while after the middle stage of drying only the inner part of the cylindrical stock presented higher value compared with the C-NC treated specimen. The distribution of the absolute vapor pressure of the V-CO treated specimen was similar to that of the V-NC treated specimen during the initial stage of drying. However, the former showed a large distribution in order of the hollow, the outer part, the inner part of the cylindrical stock after the initial stage of drying, which was entirely different model of distribution from that of the V-NC treated specimen. Surface checks and ring failures were not observed for all of the specimens, while end checks were severely occurred for the C-NC treated specimen and the V-NC treated specimen.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.4
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• pp.394-400
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• 2007

The properties and weldability of lap joints by PFSW with 1050 Al sheet was investigated according to tool shape. dimension and welding condition. Tensile shear test was carried out for lap jointed specimen, and the hardness in the joint regions was examined. Moreover interfacial joining length, metallograph and failure location of the lap-jointed cross section were discussed. Two tool types were a simple cylindrical type and a notched cylindrical type. Under joining conditions such as plunging depth of 2.2mm. rotating speed of 1600rpm and dwelling time of 3s, the tensile shear strength of lap-jointed specimen by the notched type tool was superior to that by simple cylindrical type tool. The maximum tensile shear load of lap jointed specimen was 5807N. Optimal dimensions of the notched type tool were as follows : diameters of the shoulder and pin were $18{\phi}mm$ and $10{\phi}mm$, and pin length was 2.2mm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1435-1440
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• 2014

The effects of the specimen size and temperature on the compressive strength of ATJ graphite were investigated. Compressive tests were conducted in accordance with ASTM C 965 at room temperature, $700^{\circ}C$ and $900^{\circ}C$. Three types of cylindrical specimen at room temperature were used in uniaxial tests, where the diameter-to - length ratios were one to two for the ASTM standard specimen, one to one for the Type I specimen, and one to 0.5 for the Type II specimen. Two kinds of cylindrical specimens, with and without antioxidant coating, were tested at elevated temperature. The Compressive strength of the expanded specimens(Type I, II) were slightly higher than that of standard specimen at room temperature. The compressive strength of a specimen with antioxidant coating increased as the temperature increased to $900^{\circ}C$. In contrast, that of the non-coated specimen decreases sharply due to the oxidation of the specimen.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.167-172
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• 2000

There are a variety of factors affecting measured compressive strength of hardened concrete. One of them is the end surface condition of concrete specimen. So, many capping methods have been developed for the specimen to meet the end condition requirement of ASTM C 39. A series of experimental strength comparison study was carried out using several representative capping methods, including pad capping method which is one of unbonded elastomeric capping system and was newly adopted in the ASTM standard. A comparison was also focused on their economy, convenience, harmfulness, etc.

• Composites Research
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• v.21 no.2
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• pp.25-30
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• 2008

A hemispherical microbond specimen adhered onto single carbon fiber has been proposed for evaluating the interfacial shear strength between epoxy and carbon fiber. Hemispherical microbond specimens showed low interfacial shear strength data and its small standard deviation as compared with the droplet one, which seemed to be caused by the reduction of the meniscus effects and of the stress concentration in the region contacting with the tip of pin hole. In comparison with the droplet specimen the hemispherical specimen showed the shear stress distribution similar to the cylindrical one in that low stress concentration arose around the contacting region. Average interfacial shear strength obtained by the hemispherical ones represented a good correlation with the hardness of the epoxy matrix.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.441-446
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• 2004

Mechanical systems with rubber parts have been used widely in industry fields. The evaluation of the physical characteristics of rubber is important in rubber application. Rubber material is useful to machine component for excellent shock absorbing characteristics. The impact characteristics of rubber were examined by experimental and finite element method. The impact test was conducted with a free-drop type impact tester. The ABAQUS/Explicit was used for finite element analysis. The effects of thickness and diameter of the cylindrical rubber structures were investigated. The impact absorbing ratio of the rubber material was studied order to compare the peak reaction force of the specimen which only contained aluminum against the specimen with the inserted rubber part.

• KCI Concrete Journal
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• v.14 no.1
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• pp.43-50
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• 2002

In this study, size effect tests were conducted on axial compressive strength of concrete members. An experiment of Mode I failure, which is one of two representative compressive failure modes, was carried out by using dimensionally proportional cylindrical specimens (CS). An adequate notch length was taken from the experimental results obtained from the compressive strength experiment of various initial notch lengths. Utilizing the notch length, specimen sizes were then varied. In addition, new parameters for the modified size effect law (MSEL) were suggested using Levenberg-Marquardt's least square method (LSM). The test results show that size effect was apparent for axial compressive strength of cracked specimens. Namely, the effect of initial notch length on axial compressive strength size effect was apparent.