• 한국공간구조학회논문집
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• 제17권4호
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• pp.159-165
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• 2017

In this paper, uniaxial tensile tests of ETFE films with three kinds of thicknesses(100, 200, $250{\mu}m$) and two kinds of directions(machine direction & transverse direction) are performed and the tensile strength, the tensile strain at break and the Young's modulus of ETFE films are compared for two kinds of specimen types(2 & 5). It could be figured out that there are no significant difference between tensile strengths of two specimen types but the tensile strain at break and the Young's modulus of ETFE films are affected by the specimen types. And it is concluded that the uniaxial tensile test of specimen type 2 are more reliable than that of specimen type 5.

• Journal of the Korean Wood Science and Technology
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• 제42권5호
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• pp.571-578
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• 2014

As a way of developing wooden joint development, a glass fiber reinforced wood plate was manufactured to replace a steel plate. Also, the fracture toughness was evaluated. Through application to a cantilever-type specimen made of a column and a beam, the moment resistance performance was evaluated. For the fracture toughness specimen of the wood plate, 12 types were manufactured by varying the combination of a main member (veneer and plywood) and reinforcement (glass fiber sheet and glass fiber cloth). The results of the fracture toughness test indicated that the 5% yield load of the specimen using plywood was 18% higher than that of the specimen using veneer, and that the specimen reinforced by inserting glass fiber sheets between testing materials (Type-3-PS) had the highest average 5% yield load 4841 N. Thus, a moment resistance strength test was performed by applying Type-3-PS to a column-beam joint. The results of the test indicated that compared to the specimen using a steel plate and a drift pin (Type-A), the maximum moment ratio of the specimen using a glass fiber reinforced wood plate (Type-3-PS) and a drift pin (Type-B) was 0.79; and that a rupture occurred in the wood plate due to high stiffness of the drift pin. The maximum moment ratio of the specimen using a glass fiber reinforced wood plate (Type-3-PS) and a glass fiber reinforced wooden laminated pin (Type-C) was 0.67, which showed low performance. However, unlike Type-A, a ductile fracture occurred on Type-C, and the load gradually decreased even after the maximum moment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.79.2-79
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• 2002

1. the principal of a PSD(Position Sensitive Detector) 2. the optical system of the proposed method 3. signal processing 4. experimental result A mechanical engineer experiment on the tension test. In this experiment, they use the extensometer which can measure the extended distance of material. A normal extensometer is the contact type which means that the extensometer should attached to the specimen. It is not convenient to the user. The contacting type can also effect the characteristic of the specimen. So a extensometer is changed from contacting type to non-contacting type. Non-contacting type is not necessary to attach the extensometer to the specimen...

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.67-72
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• 2008

The objective of this study is to design a laboratory specimen for simulating residual stress of circumferential butt welding of pipe. Specimen type and method for residual stress generation were proposed based on the review of prior studies and parametric finite element simulation. To prove the proposed specimen type and loading method, the residual stress was generated using the designed specimen by applying proposed method and was measured. The measured residual stress using X-ray diffraction reasonably agreed with the results of finite element simulation considered in the specimen design. Comparison of residual strains measured at several locations of specimen and given by finite element simulation also showed good agreement. Therefore, it is indicated that the designed specimen can reasonably simulate the residual stress of circumferential butt welding of pipe.

• 한국안전학회지
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• 제24권1호
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• pp.7-13
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• 2009

The objective of this study is to design a laboratory specimen for simulating residual stress of circumferential butt welding between pipes. Specimen type and method to generate residual stress were proposed based on the review of prior studies and parametric finite element analysis. To prove the proposed specimen type and loading method, the residual stress was generated using the designed specimen by applying proposed method and was measured. The measured residual stress using X-ray diffraction reasonably agreed with the results of finite element analysis considered in the specimen design. Comparison of residual strains measured at several locations on the specimen and given by finite element simulation also showed good agreement. Therefore, it is indicated that the designed specimen in this study can reasonably simulate the axial residual stress of a circumferential butt welding of pipe.

• 대한기계학회논문집A
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• 제38권12호
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• pp.1435-1440
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• 2014

로켓 노즐 목에 이용되는 ATJ 그라파이트에 대해 시편크기 및 온도에 따른 압축강도를 평가하였다. 압축시험은 ASTM C 965 규정에 준하여 상온 및 고온에서 수행되었다. 상온에서는 직경 대 높이 비가 1:2 인 ASTM 규정에 부합하는 표준시편 및 직경 대 높이비가 1:1 및 1:0.5 인 Type I, Type II 등 2종류의 확대시편이 일축 압축시험에 이용되었다. 또한 고온에서는 산화제를 도포한 코팅시편 및 일반시편을 이용하였다. 시험결과 상온에서 모든 확대시편들이 표준시편보다 약간의 압축강도 증가를 보였다. 고온환경에서의 압축시험결과 코팅시편은 $900^{\circ}C$ 까지 압축강도가 유지되거나 약간의 증가를 보였으나, 일반시편은 산화로 인해 압축강도가 급격하게 감소했다.

• 대한기계학회논문집
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• 제19권1호
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• pp.161-169
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• 1995

One of the most influential factors on estimating the complex modulus by using longitudinal vibration of a rod-type specimen is the accuracy of the approximate models for describing the dynamic behavior of the specimen. Performance of several approximate models is investigated analytically on the basis of the Pochhammer-Chree theory in case of infinite specimen and numerically on the basis of the finite element analysis in case of finite specimen. The frequency range where each model gives good approximation and its accuracy in that range are determined.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2002년도 학술.기술논문발표회
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• pp.11-15
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• 2002

This study is intended to analyze the relationship between the rebound value of P type schmidt hammer and the compressive strength for a quality control of concrete. According to the results, the compressive strength of standard curing specimen increases in proportion to age, but that of air curing specimen hardly increases after 28 days. The rebound value of P type schmidt hammer, however, increases due to carbonation of concrete in air curing specimen. The correlativity between the rebound value and the compressive strength is very favorable in the case of standard curing specimen, but drops remarkably in the case of air curing specimen. Thus, as application of age coefficient is required for exact estimation of the compressive strength, the age coefficient is derived from this study. The age coefficient of P type schmidt hammer is higher at the age of 3 and 7days, and drops significantly, compared with the age of 28days. And it is lower before 28days than that of N type schmidt hammer suggested in Japan, and shows the similar tendency after 28days.

• 전기학회논문지
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• 제56권5호
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• pp.869-875
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• 2007

Magnetic properties of electrical steel are, in general. measured by using Epstein frame or single sheet tester (SST). These methods, however, require very strict regulation of a specimen in its size and shape. thus, can not be easily applied to various types of specimen. On the other hand, a ring-test method, which measures only the isotropic properties, can be easily applied to most cases because it requires a toroidal-type specimen of arbitrary size. This method, especially, is considered as an unique available method for a bulk-type specimen. In this paper, a ring-test method is developed, and applied to the measurement of magnetic properties of a bulk-type electrical steel with a toroidal-type specimen. In the measurement, the magnetic properties and iron losses are measured and compared with each other at the both sinusoidal magnetic flux density and sinusoidal magnetic field intensity conditions under 0.2Hz and 60Hz alternating magnetic fields excitation. Through experimental measurements, a sinusoidal magnetic flux density condition is proven appropriate for the measurement of magnetic properties, including iron loss characteristics, of electrical steels.

• 한국분말재료학회지
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• 제5권4호
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• pp.265-272
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• 1998

For the purpose of investigating the effect of sintering atmosphere and carbon addition on sintered density and microstructural characteristics, the M3/2 grade high speed steel powders with the addition of carbon are sintered in vacuum and $20%H_2/79%N_2/l%CH_4$ gas atmosphere. With the addition of 0 wt%C, 0.45wt%C and 1.15 wt%C the optimum sintering temperatures decrease down to $1260^{\circ}C$, $1210^{\circ}C$ and $1150^{\circ}C$ respectively for the vacuum sintered specimen, and also decrease down to $1130^{\circ}C$, $1120^{\circ}C$ and $1115^{\circ}C$ for the gas sintered specimen. The threshold temperatures for full densification decrease steeply with increasing carbon content of the sintered specimen, while this temperatures are slowly decreased at high carbon content. The vacuum sintered specimen shows the primary carbides of MC and $M_6C$ type at the optimum sintering temperature, and eutectic carbides of $M_2C$ and Fe-Cr type are produced in the oversintered specimen. The gas sintered specimen exhibits M6C and Fe-Cr type primary carbides at the optimum sintering temperature. The eutectic carbides of $M_6C$ and Fe-Cr type and MX type carbonitride are shown for the oversintered specimen in the gas atmosphere. The hardness of gas sintered specimen shows high value of 830-860 Hv due to the increment of carbide precipitation.