• 미생물학회지
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• 제10권1호
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• pp.9-28
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• 1972

1. To get the suitable yeasts for the tratment of waste liquor from pulp and paper industries, the 162 yeasts were isolated from the waste liquor, decayed trees and sewage (1, 7, 8, 9, 1971). 17 species were chosen by its ability to assimilate the carbon compounds and indentified. 2. All of the strain was increased its growing ability by agitation. In particular, the strain 912, strain 613, strain 100, strain 732 showed excellent high productive ratio(A/$A_{0}$). 3. The optimum temperature of the strains rangel $27^{\circ}C$ and $30^{\circ}C$. 4. Most of the strain was grown actively in 10C/5N-composition and strain 113, strain 432, strain 735, strain 936, and strain 912 showed its optimum growing in 15C/5N-composition and 5C/5N-composition, respectively. 5. The optimum pH of the strains lay within range pH 4.5-6. Effect of the variation of pH on the growth was nearly negligible within this range. 6. The strain 912, strain 100, strain 613, strain 311, strain 235, and strain 732 were expected for the utilization to the treatment of the waste liquor from pulp and paper industries.

• 한국재료학회지
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• 제26권5호
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• pp.281-286
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• 2016

In the present study, the tensile properties and dynamic strain aging of an Fe-24.5Mn-4Cr-0.45C alloy were investigated in terms of strain rate. During tensile testing at room temperature, all the stress-strain curves exhibited serrated plastic flows related to dynamic strain aging, regardless of the strain rate. Serration appeared right after yield stress at lower strain rates, while it was hardly observed at high strain rates. On the other hand, strain-rate sensitivity, indicating a general relationship between flow stress and strain rate at constant strain and temperature, changed from positive to negative as the strain increased. The negative strain-rate sensitivity can be explained by the Portevin Le Chatelier effect, which is associated with dynamic strain aging and is dependent on the strain rate because it is very likely that the dynamic strain aging phenomenon in high-manganese steels is involved in the interaction between moving dislocations and point-defect complexes.

• 한국전기전자재료학회논문지
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• 제22권1호
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• pp.67-73
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• 2009

The stress-strain behavior and its effects on the crack initiation and growth of ITO film on PET substrate with a sheet resistance of 45 ohms/sq were investigated. Electrical resistance increased gradually at the strain of 0.7% in the elastic to plastic transition region of the stress strain curves. Numerous cracks were observed after 1% strain and the increase of the resistance can be linked to the cracking of ITO thin films. The onset strain for the increase of resistance increased with increasing strain rate, suggesting the crack initiation is dependent on the strain rate. Upon loading, the initial cracks perpendicular to the tensile axis were observed and propagated the whole sample width with increasing strain. The spacing between horizontal cracks is thought to be determined by the fracture strength and the interfacial strength between ITO and PET. The crack density increased with increasing strain. The spacing between horizontal cracks (perpendicular to the stress axis) increased with decreasing strain rate, The increase of crack density with decreasing strain rate can be attributed to the higher fraction of the plastic strain to the total strain at a given total strain. As the strain increased over 5% strain, cracks parallel to the stress axis were developed and increased in number with strain, accompanied by drastic increases of resistance.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1996년도 추계학술대회논문집
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• pp.85-92
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• 1996

The Measurement method of the plastic strain ratio is various in Automotive sheet steel. In this paper, the measurement of the plastic strain are used two different methods, ASTM E 517 method and the automatic strain measurement tensile specimen during the tensile test, and compared the plastic strain ratios from the two methods. The experimental results showed that the measured plastic strain ratios from the automatic strain measurement method are coincide with that from the ASTM E 517 standard measurement in various specimens. Therefore, automatic strain measurement method by two extensometers shows good accuracy. Also, the strain dependance of plastic strain ratios could be recorded by the computer continuously and anisotropy of the strength coefficient, K, and strain hardening exponent, n ,could be compared with each direction automatically through the use of automatic strain measurement system.

• 대한의용생체공학회:의공학회지
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• 제16권3호
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• pp.325-330
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• 1995

혈압에 의한 안쪽벽의 변형을 집중현상으로 인한 동백 전단부의 변형율 gradient의 심각성은 잔유 변형율에 의해 감소되거나 없을 수 있다는 가정을 실험적으로 시도했다. 잔유변형율과 압력에 의한 변형율을 측정하여 잔유변형율이 원주변형율에 끼치는 영향을 알아 보았다. 결과로서 변형율 gradient를 줄이거나 없을수도 있으나 negative gardient가 평균적으로 나타났다. 즉 전체변형율(원주변형율+잔유변형율)은 안쪽벽이 낮고 바깥쪽이 높은 것으로 나타났다.

• Nuclear Engineering and Technology
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• 제10권2호
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• pp.73-78
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• 1978

온도 및 연신율변화 (strain-rate change)가 $\alpha$-uranium의 변형거동에 미치는 영향을 30$0^{\circ}C$에서 55$0^{\circ}C$까지 연구하였으며, strain rate sensitivity, activation volume, strain rate sensitivity exponent 및 dislocation velocity exponent을 조사하였다. 40$0^{\circ}C$이하에서 strain rate sensitivity exponent는 strain의 증가에 따라 증가하였으나 50$0^{\circ}C$이상에서는 strain의 증가에 따라 감소하는 경향을 나타냈다. 40$0^{\circ}C$이하에서는 strain에 의해 생기는 가공경화로 인한 내부 용력의 증가가 strain rate sensitivity exponent에 영향을 미치나 50$0^{\circ}C$이상에서는 많은 slip system이 변형에 기여하게 되므로 가공경화 보다는 thermal softening이 더 큰 영향을 미쳐서 strain rate sensitivity가 감소된다고 추측된다.

• Structural Engineering and Mechanics
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• 제84권2호
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• pp.239-251
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• 2022

The use of lateral reinforcement in confined concrete columns can improve bearing capacity and deformability. The lateral responses of lateral reinforcement significantly influence the effective confining pressure on core concrete. However, lateral strain-axial strain model of concrete columns confined by lateral reinforcement has not received enough attention. In this paper, based on experimental results of 85 concrete columns confined by lateral reinforcement under axial compression, the effect of unconfined concrete compressive strength, volumetric ratio, lateral reinforcement yield strength, and confinement type on lateral strain-axial strain curves was investigated. Through parameter analysis, it indicated that with the same level of axial strain, the lateral strain slightly increased with the increase in the unconfined concrete compressive strength, but decreased with the increase in volumetric ratio significantly. The lateral reinforcement yield strength had slight influence on lateral strain-axial strain curves. At the same level of lateral strain, the axial strain of specimen with spiral was larger than that of specimen with stirrup. Furthermore, a lateral strain-axial strain model for concrete columns confined by lateral reinforcement under axial compression was proposed by introducing the effects of unconfined concrete compressive strength, volumetric ratio, confinement type and effective confining pressure, which showed good agreement with the experimental results.

• 반도체디스플레이기술학회지
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• 제14권2호
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• pp.23-27
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• 2015

In this paper, eco-friendly paper strain gauge was fabricated in the way of printing strain gauge on paper substrate, using PEDOT:PSS ink and inkjet printer technology. As a p-type conductive high polymer, PEDOT:PSS is known to be piezoresistive effect. I formed a strain gauge by connecting in parallel 5 lines of $60{\mu}m$ width printed with PEDOT:PSS. To minimize surrounding influence such as temperature, I formed wheat-stone bridge by combining 4 strain gauges (quarter-bridge strain gauge) which were made up of PEDOT:PSS 5 lines and measured. In quarter-bridge strain gauge, only two strain gauges, facing each other, arranged in strain and horizontal direction were deformed while the other two strain gauge of vertical direction were not. Therefore, quarter-bridge strain gauge showed the output of half bridge. The fabricated quarter-bridge strain gauge had output sensitivity of $105.6{\mu}V/V{\cdot}mm$ and its output linearity was relatively good.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 추계학술대회
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• pp.151-153
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• 1995

Residual strain of artery is studied. There has been experimental evidence that residual strain exists in artery. When ring of artery is longitudinally cut, it is opened. Since strain has been determined without considering residual strain, the existence of residual strain is meaningful in mechanics of arterial wall. Intimal strain concentration is considered to be reduced with both account of residual strain and strain determined by loading. However, it is lack of experimental research. Therefore, this study experimentally attempts to quantify the effect of residual strain on circumferential strain which is determined under the assumption of zero strain with zero pressure.

• 소성∙가공
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• 제20권7호
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• pp.498-503
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• 2011

The strain rate sensitivity index, m, plays an important role in plastic deformation at elevated temperatures. It is affected by strain rate, temperature, and the microstructure of the material. The strain rate sensitivity index has been used as a constant in numerical analysis of plastic forming at a specified strain rate and temperature. However, the value of m varies as deformation proceeds at an elevated temperature and a certain strain rate. Thus, in this present study, the value of m has been characterized as a function of strain by multiple tensile jump tests for AZ31 magnesium alloy sheet, and the variation of m has been discussed in conjunction with the microstructural observations before and after deformation. The experimental results show that the variation of m is dependent on the temperature and strain rate. Grain growth with dynamic recrystallization also affects the variation of m.