• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.380-381
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• 2009

This paper describes effect of the bending strain of FRP tube for composite bushing with winding tension. The composite bushing can be formed, by adding silicone rubber sheds to a tube of composite materials. The FRP tube is internal insulating part of a composite bushing and is designed to ensure the mechanical characteristics. Generally the properties of FRP tube can be influenced by the winding angle, wall thickness and winding tension. As winding tension is increased glass contents was increased in the range of 70.4~76.6%. In the bending test, winding tension is increased residual displacement was decreased in the range of 14.0~12.2 mm.

• 한국전산구조공학회논문집
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• 제15권1호
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• pp.69-84
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• 2002

본 논문에서는 축방향 인장 부재의 균열거동과 철근콘크리트 부재의 인장강화현상을 고려하기 위한 새로운 해석적 기법을 제시하였다 균열 후 거동 규명을 위하여 부착응력-슬립의 관계나 부탁 응력의 분포를 가정하는 기존의 해석방법과는 달리, 철근과 콘크리트의 변형률 분포 함수를 다항식으로 가정하여, 이를 바탕으로 일축 인장부재의 균열 해석 기법을 구성하였다. 제시한 균열 해석모델은 기존의 해석기법과 비교하여, 철근콘크리트 구조물의 유한요소해석을 위한 균열 후의 평균 응력-변형률 관계를 정의하거나, 부재의 길이방향으로 철근과 콘크리트가 분담하는 하중 및 슬립량 산정시 매우 효율적이다. 제안된 모델을 이용하여 얻어진 균열하중과 보강철근의 신장률 값을 다른 해석기법 및 실험값과 비교한 결과 만족할만한 정확도를 보여주었다.

• 국제강구조저널
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• 제18권5호
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• pp.1784-1800
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• 2018

Tension-shear loading is a common loading condition in steel structures during the earthquake shaking. To study ductile fracture in structural steel under multiple stress states, experimental investigations on the different fracture mechanisms in Chinese Q235 steel were conducted. Different tension-shear loading conditions achieved by using six groups of inclined notch butterfly configurations covering pure shear, tension-shear and pure tension cases. Numerical simulations were carried out for all the specimens to determine the stress and strain fields within the critical sections. Two tension-shear fracture models were calibrated based on the hybrid experimental-numerical procedure. The equivalent fracture strain obtained from the round bar under tensile loading was used for evaluating these two models. The results indicated that the tension-shear criterion as a function of the shear fracture parameter had better performance in predicting the fracture initiation of structural steel under different loading conditions.

• 대한기계학회논문집A
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• 제28권6호
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• pp.848-859
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• 2004

Mechanical testing methods to determine the material constants for large deformation nonlinear finite element analysis were demonstrated for natural rubber. Uniaxial tension, uniaxial compression, equi-biaxial tension and pure shear tests of rubber specimens are performed to achieve the stress-strain curves. The stress-strain curves are obtained after between 5 and 10 cycles to consider the Mullins effect. Mooney and Ogden strain-energy density functions, which are typical form of the hyperelastic material, are determined and compared with each other. The material constants using only uniaxial tension data are about 20% higher than those obtained by any other test data set. The experimental equations of shear elastic modulus on the hardness and maximum strain are presented using multiple regression method. Large deformation finite element analysis of automotive transmission mount using different material constants is performed and the load-displacement curves are compared with experiments. The selection of material constant in large deformation finite element analysis depend on the strain level of component in service.

• 대한기계학회논문집
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• 제10권5호
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• pp.645-652
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• 1986

본 연구는 이상의 연구결과들을 비교한 결과, Hill에 의하여 최근에 제안된 새 항복조건식에 의한 해석방법을 종합 검토함으로써, 실험결과와 이론적 해석결과 와의 합리적인 접근을 얻을 수 있다고 예상하여 수행되었다. 더 나아가 Pearce가 그의 연구 결과에 대한 고찰에서, 아마도 R 값(Lankford값)이 변형도중에 계속 일정 하게 유지되지 않을 것이며, 그것이 실험결과가 이론적 해석결과와 일치하지 않는 한 가지 원인이 될 수 있다고 언급한 사실을 고려하고, 최근 R 값에 대한 연구에서 R 값 이 변형률의 크기에 의존된다는 사실을 감안하여 R 값을 실제로 측정하였으며, 그 결 과를 등 2축인장에서의 응력-변형률선도를 해석하는데 적용하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제20권4호
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• pp.36-40
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• 2018

In this study, the electromechanical properties in Sn-Cu double layer stabilized GdBCO coated conductor (CC) tapes with and without external lamination under uniaxial tension were examined at 77 K and self-field. Their irreversible stress and strain limits were determined using a loading-unloading scheme based on different critical current ($I_c$) recovery criteria. The repeated tests were performed and statistical estimation was done to check the reproducibility depending on the criterion adopted in evaluating the electromechanical properties. From the results, it showed that the Sn-Cu double-layer stabilized CC tapes have the higher irreversible stress limit, but lower irreversible strain limit as compared to brass laminated ones. Through the repeated tests, it can be found that a small scattering of irreversible limits existed in both CC tape samples. Finally, similar strain sensitivity of $I_c$ in both CC tapes was obtained.

• 환경위생공학
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• 제11권3호
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• pp.69-77
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• 1996

The result of isolated and selected to the strain having the emulsifying activity from soil's strain the strain was identified as Candida genus. The strain was investigated with culture condition at pH culture temperature, flow rate of air, strring rate etc., and physicochemical properties of the biosurfactant were examined. The optimum composition of medium for a strain cultivation were obtained as follow : glucose ; 100g/L, yeast extract ; 10g/L, urea ; 1.0g/L, KH$_{2}$PO$_{4}$ ; 50mg/L, MgSO$_{4}$ ; 500mg/L, and the op condition of cultivation was as follow : pH ; 3.0, temperatlue ; 24$\circ $C, strring rate ; 40rpm. The maximum yield of biosurfactant was obtained by pH ; 3.0-3.5, and temperature ; 25$\circ $C. The degree of emulsification of syntesized biosurfactant was increased clearly by increasing concentration of biosurfactant and it's stability was maintained for a long time. The surface tension of biosurfactant was varied with pH, especially it was showed that the surface tension was high at acidic pH.

• 한국기계가공학회지
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• 제13권4호
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• pp.75-82
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• 2014

A pin-type load-cell which uses shear-type strain gauges was developed to measure the tension of a wire in a winch. A finite element analysis was performed to determine the locations of the strain gauges. All of the shear-type strain gauges were attached onto parts that undergo regularly shear stress distributions. A Wheatstone bridge circuit was used to connect each of the gauges and to measure the strains. Linearity within the 5% error range was noted when testing the pin-type load-cell.

• 센서학회지
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• 제30권3호
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• pp.181-184
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• 2021

Interest in healthcare and wearable devices has been increasing recently. A strain sensor is required in various wearable devices. With respect to such devices, studies on resistance changes in strain sensors using flexible materials are in progress. However, the resistance of the rest area in a strain sensor should not change according to the applied strain. So, an electrode with resistance to stretching, bending, and torsion is required in such strain sensors. Tension, bending, and torsion can be realized through structural shape control, rather than by using flexible materials. Further, such an electrode that maintains electrical properties has been developed and manufactured. This electrode can be used in various applications such as foldable devices, e-papers, batteries, and multifunctional wearable devices.

• 대한기계학회논문집A
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• 제21권2호
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• pp.261-271
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• 1997

This paper presents the design process and characteristic test results of tension sensors for measuring the ultimate tension forces of surgical wires. Three types of sensor were designed and tested for calibration. The first two types which transfer the wire tension to the sensing element by direct contact have too much hysterisis errors due to the firctional effect. This error can be considerably reduced in the modified structure, where a cover and a loading button is used to transfer force and moment to the sensing element. The strains predicted by theoretical equations agree well with those by finite element calculations neglecting friction and the strains by finite element analysis considering friction are in good agreement with those measured by four strain gages. The modified ring type tension sensor developed in this paper is expected to be useful for measuring the tension of surgical wires with nonlinearity of 1.31%FS, hysterisis of 5.74%FS and repeatability of 0.19%FS.