• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.3
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• pp.48-52
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• 2006

Through-the-thickness properties of thick-walled cylindrical composites are required to determine structural performances because interlaminar tensile stress is primarily responsible for structural failure of the composites during their curing process. It is necessary for evaluating the tensile properties to find individual test methods to find appropriate methods because there are no recognised international standards(test methods and test specifications) available for generating reliable tensile properties in the direction. This paper has performed an experimental study to measure that properties of carbon fabric/phenolic composites which are produced by domestic company. Several test methods using an aluminum specimen were compared and evaluated. The best test method to measure transverse through-the-thickness properties of composite materials was developed by the experimental results that strain trends on all faces of composite specimen are the same.

• Composites Research
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• v.23 no.5
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• pp.22-29
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• 2010

This paper describes the evaluations of tension-compression fatigue characteristics and life for glass fiber/epoxy laminate composite applied to railway bogie to reduce weight. Test samples of tension-compression fatigue were composed of glass fiber/epoxy 4-harness woven laminate composites with different stacking sequence of warp-direction, fill-direction and ${\pm}45^{\circ}$-direction. The tension-compression fatigue test was conducted with stress ratio (R) of -1 and frequency of 5Hz. Goodman diagram were used to evaluate the fatigue characteristics and life of glass fiber/epoxy 4-harness satin woven laminate composite. Anti-buckling jig was designed to prevent buckling of specimen under compression load. The test results showed that the fatigue characteristics of glass fiber/epoxy 4-harness satin woven laminate composite with stacking sequence of warp-direction had a good performance in comparison with that of SM490 used to conventional metal railway bogie.

• Tunnel and Underground Space
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• v.26 no.4
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• pp.316-326
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• 2016

The purpose of this study is to investigate the influence of cleavages on indirect tensile strength (ITS) of the granite. Brazilian disc tests and ring tests with three different hole sizes were performed. 2D DEM (Discrete Element Method) simulation was employed to further understand the failure process during the tests and the mechanism behind. Results show that ITS decreases across hardway, grain and rift cleavage. Measured average ITS from ring tests is about 2.5 ~ 6.4 times of those measured from Brazilian disc tests, and it decreases with increasing ratio of diameters of inner hole and specimen. Failure pattern in ring tests is influenced by both hole size and relative positions of cleavages parallel and perpendicular to the loading direction.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.331-341
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• 2015

The main purpose of this study is reducing the cost and effort for characterization of tensile strength of fiber reinforced concrete, in order to use in structural design. For this purpose, in this study, test for fiber reinforced concrete was carried out. Because fiber reinforced concrete is consisted of diverse material, it is hard to define the correlation between mix proportions and strength. Therefore, compressive strength test and tensile strength test were carried out for the range of smaller than 100 MPa of compressive strength and 0.25~1% of steel fiber volume fraction. as a results of test, two types of tensile strength were highly affected by compressive strength of concrete. However, increase rate of tensile strength was decreased with increase of compressive strength. Increase rate of tensile strength was decreased with increase of fiber volume fraction. Database was constructed using previous research data. Because estimation equations for tensile strength of fiber reinforced concrete should be multiple variable function, linear regression is hard to apply. Therefore, in this study, we decided to use the ANN(Artificial Neural Network). ANN was constructed using multiple layer perceptron architecture. Sigmoid function was used as transfer function and back propagation training method was used. As a results of prediction using artificial neural network, predicted values of test data and previous research which was randomly selected were well agreed with each other. And the main effective parameters are water-cement ratio and fiber volume fraction.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.14-19
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• 2004

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.47-52
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• 2024

The demand for FRPs that are corrosion-free and have an excellent tensile strength-to-weight ratio. However, there is a lack of research on the mechanical properties of FRP in the form of rebars, especially the changes in performance due to heating. Therefore, in this paper, 60 tensile and compression specimens of CFRP rebars with a diameter of 12 mm were fabricated and subjected to direct tensile and direct compression tests, and their performance was evaluated according to the heating temperature. It was found that as the heating temperature increases above 300 ℃, the performance decrease becomes larger due to the burning of epoxy. The compressive strength was found to be much lower than the tensile strength, but the modulus of elasticity was found to be the same in tension and compression.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.130-130
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• 2017

비닐하우스의 골조를 구성하는 파이프는 부식을 방지할 목적으로 아연도강관을 사용한다. 그러나 시간이 지남에 따라 아연도금량 감소와 여러 외부 환경인자 등에 의하여 부식이나 침식이 진행되어, 외관상 녹이 생기고 강도와 연신율 등이 감소하게 된다. 이는 비닐하우스 전체의 내구성을 저하시키는 요인으로 작용하게 되는데, 이를 평가하기 위한 방법이나 기준은 미비한 실정이다. 이에 본 연구에서는 농업시설의 내구성을 평가하기 위한 방법의 하나로 각기 다른 경과년수를 갖는 비닐하우스로부터 채취한 서까래 파이프의 인장 시험을 실시하였다. 인장 시험에 사용된 서까래 파이프는 (구)시설원예시험장에 설치되어 있는 비닐하우스에서 경과년별로 채취하였으며, 지중매설부와 지상노출부로 구분하여 시편을 제작하였다. 인장 실험 결과 서까래 파이프의 경과년이 오래될수록 시편의 인장 강도는 작아지는 경향을 보이고 있으나, 파단연신율은 경과년과 연관성을 찾아보기 어려운 것으로 나타났다. 그리고 동일한 경과년을 갖는 서까래 파이프 시편에서 지중매설부의 인장 강도와 파단연신율이 지상노출부에 비해 대체로 작게 측정되었으며, 경과년이 증가할수록 인장 강도의 감소폭이 커지는 경향을 보이는 것으로 나타났다.

• Journal of Korean Association for Spatial Structures
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• v.10 no.1
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• pp.51-58
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• 2010

ETFE is the abbreviation of Ethylen Tetra Fluoro Etylene, a sort of colorless and transparent granules. The advantage ETFE film has daylight transmission and chemical the resistance and The thickness of ETFE film is used to from $50{\mu}m$ to $300{\mu}m$ and tensile strength of ETFE film changes from 40MPa to 60MPa and the tensile strain at break can get to about 300-400%. In this paper, ETFE film carried out the tensile proprieties, such as the tensile strain at break, the tensile strength are examined.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.341-346
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• 2010

The effect of specimen geometry on the bending and tensile strengths of dissimilar joints ($\beta-Si_3N_4/S45C$) with copper interlayers was evaluated. The average bending strength of specimens with circular cross sections was higher than that of specimens with rectangular cross sections. The crack initiation stress ($\sigma_i$) was successfully determined by the acoustic emission (AE) method and was approximately 60~80% of the bending strength. The residual stresses near the interfaces on the ceramic side were measured by X-ray diffraction before conducting the bending test. The bending strength and the crack initiation stress decreased with an increase in the residual stresses. The effect of the bending strain component was evaluated by the tensile testing; the tensile strength decreased with an increase in the bending strain component and was approximately 80% of the bending strength.

• Tunnel and Underground Space
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• v.7 no.4
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• pp.284-292
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• 1997

본 연구에서는 파괴형상의 특성을 이용하여 암석인장강도 측정실험법의 적용성을 평가하여Tekl. 이를 위해 화강암 및 석회암 시료를 대상으로 하여 점하중 시험법, Brazilian 시험법을 통해 인장파괴를 유도하였다. 각 파괴면의 형상을 분석하였고, Hoop 시험법의 경우 이론적인 응력분포와 함께 해석하였다. 파괴면 형상의 특징은 향후 시추코어의 파괴면 해석, 야외조사시 절리면의 파괴 해석 등에 이용될 수 있다.