• 대한화학회지
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• 제58권3호
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• pp.251-257
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• 2014

Poly(methyl acrylate)-poly(acrylonitrile) 공중합체의 응력완화 실험은 용매기를 부착한 인장 시험기를 사용하여 여러 온도의 공기 중, 증류수 용액에서 실행하였다. Eyring-Halsey 모델의 이론적인 응력완화식에 응력완화 실험 결과를 적용하여 여러 가지 유동 파라메타를 계산하였다. 비결정성 영역에서의 유동단위의 고찰을 위하여 유동 파라메타와 결정크기로부터 섬유고분자 물질의 자체확산, 홀 부피, 점성, 열역학파라메타 등을 계산하였다. 이들 시료의 유동 파라메타는 유동 단위의 홀부피, 자체확산, 유동 열역학 파라메타와 직접적인 연관을 갖는 것으로 규명되었다.

• Elastomers and Composites
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• 제47권3호
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• pp.223-230
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• 2012

응력완화 실험 곡선을 Eyring-Halsey 비뉴톤 모델의 이론식에 적용하여 poly(methyl acrylate)-poly(acrylonitrile) 공중합체의 유변학적 파라메타를 얻었다. 응력완화 실험은 용매기를 부착한 인장 시험기를 사용하였다. 유동 파라메타를 컴퓨터 프로그램을 이용하여 계산하였다. 이들 시료의 유동 파라메타는 유동 단위의 자체확산, 유동점성, 유동 활성화 에너지와 직접적인 연관을 갖는 것으로 규명되었다.

• 폴리머
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• 제35권3호
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• pp.232-237
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• 2011

Polyacrylonitrile-poly (vinyl chloride) 공중합체의 완화스펙트럼을 이론적인 완화스펙트럼 식에 실험적인 응력완화 곡선을 대입하여 계산하였다. 이론적인 완화스펙트럼 식은 Ree-Eyring and Maxwell 모델로부터 유도하였다. 응력완화 실험은 용매기를 부착한 인장 시험기를 사용하였다. 완화스펙트럼의 계산은 컴퓨터 프로그램을 이용하였으며, 완화스펙트럼으로부터 고체 고분자의 미세구조, 점탄성적인 성실, 홀 부피가 연구되었다. 또한 이들 시료의 완화스펙트럼은 유동단위의 분자량과 자체확산 분포와 밀접한 관계가 있음을 알 수 있었다.

• Advances in nano research
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• 제10권3호
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• pp.221-234
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• 2021

During the previous few years, phenomenon of bioconvection along with the use of nanoparticles showed large number of applications in technological and industrial field. This paper analyzed the bioconvection phenomenon in magnetohydrodynamic boundary layer flow of a Powell-Eyring nanoliquid past a stretchable cylinder with Cattaneo-Christov heat flux. In addition, the impacts of chemical reaction and heat generation/absorption parameter are considered. By the use of appropriate transformation, the governing PDEs (nonlinear) have been transformed and formulated into nonlinear ODEs. The resulting nonlinear ODEs subjected to relevant boundary conditions are solved analytically through homotopy analysis method which is programmed in Mathematica software. Graphical and numerical results versus physical quantities like velocity, temperature, concentration and motile microorganism are investigated under the impact of physical parameters. It is noted that velocity profile enhances as the curvature parameter A and Eyring-Powell fluid parameter M increases but a decline manner for large values of buoyancy ratio parameter Nr and bio-convection Rayleigh number Rb. In the presence of Prandtl number Pr, Eyring-Powell fluid parameter M and heat absorption parameter ��, temperature profile decreases. Nano particle concentration profile increases for increasing values of magnetic parameter Ha and thermophoresis parameter Nt. The motile density profile has revealed a decrement pattern for higher values of bio-convection Lewis number Lb and bio-convection peclet number Pe. This study may find uses in bio-nano coolant systems, advance nanomechanical bio-convection energy conversion equipment's, etc.

• Journal of the Korean Data and Information Science Society
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• 제7권1호
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• pp.21-35
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• 1996

In this paper, estimation and prediction procedures are discussed for grneral situation in which the failure time follows the independent density $f_{i}({\varepsilon}_{i})$ for the accelerated life testing under Type II censoring. In the context of accelerated life test experiment, procedures are given for estimating the parameters in the Eyring model, and for estimating mean life at a given future stress level. The procedures given are conditional confidence interval procedures, obtained by conditioning on ancillary statistics. A comparison is made of these procedures and procedures based on asymptotic properties of the maximum, likelihood estimates.

• 대한안전경영과학회지
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• 제9권5호
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• pp.43-48
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• 2007

This paper is to present linkage parameter to integrate statistical models and physical models for accelerated life test. Statistical models represent the relationship of probability distribution and life. Physical models show the relationship of life and stress. Moreover, this study proposes the four steps for construction of integrated models for accelerated life test using linkage parameter. Finally, this paper develops new integrated models such as extreme value distribution-general Eyring, linearly increasing failure rate function-general Eyring, etc., and estimates various reliability measures.

• 산업식품공학
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• 제13권1호
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• pp.70-73
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• 2009

The yield stress of stirred yogurt was measured by the vane viscometer at different pre-shearing conditions, such as pre-shear speed, pre-shear time, and wait time, and temperature (12-38${^{\circ}C}$). The yield stress ranged from ~17.6 to 10 Pa and from 34.2 to 11.9 Pa, depending on the pre-shearing conditions and temperature, respectively. The preshear speed and the wait time significantly affected the yield stress. The temperature dependence of the yield stress was described by the Eyring's kinetic model. The linear function of the temperature on the yield stress was limited at the 22${^{\circ}C}$, and at the above 22${^{\circ}C}$, the yield stress was maintained to be a constant (~12.5 Pa).

• 대한기계학회논문집A
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• 제29권5호
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• pp.689-697
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• 2005

This paper presents the reliability estimation of door hinge for home appliances, which consists of bushing and shaft. The predominant failure mechanism of bushing made of polyoxymethylene(POM) is brittle fracture due to decrease of strength caused by voids existing, and that of shaft made of acrylonitrile-butadiene-styrene(ABS) is creep due to plastic deformation caused by excessive temperature and lowering of glass transition temperature by absorbed moisture. Since the brittle fracture of bushing is overstress failure mechanism, the load-strength interference model is used to estimate the failure rate of it along with failure analysis. By the way, the creep of shaft is wearout failure mechanism, and an accelerated life test is then planned and implemented to estimate its lifetime. Through the technical review about failure mechanism, temperature and humidity are selected as accelerating variables. Assuming Weibull lifetime distribution and Eyring model, the life-stress relationship and acceleration factor, $B_{10}$ life and its lower bound with $90\%$ confidence at worst case use condition are estimated by analyzing the accelerated life test data.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2004년도 정기학술대회
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• pp.303-311
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• 2004

This paper presents the reliability estimation of door hinge for home appliances, which consists of bushing and shaft. The predominant failure mechanism of bushing made of polyoxymethylene(POM) is brittle fracture due to decrease of strength caused by voids existing, and that of shaft made of acrylonitrile-butadiene-styrene(ABS) is creep due to plastic deformation caused by excessive temperature and lowering of glass transition temperature by absorbed moisture. Since the brittle fracture of bushing is overstress failure mechanism, the load-strength interference model is used to estimate the failure rate of it along with failure analysis. By the way, the creep of shaft is wearout failure mechanism, and an accelerated life test is then planned and implemented to estimate its lifetime. Through the technical review about failure mechanism, temperature and humidity are selected as accelerating variables. Assuming Weibull lifetime distribution and Eyring model, the life-stress relationship and acceleration factor, B$_{10}$ life and its lower bound with 90% confidence at worst case use condition are estimated by analyzing the accelerated life test data.a.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2004년도 정기학술대회
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• pp.239-246
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• 2004

가속열화시험은 가속수명시험시에 고장 개수가 적거나 심지어 고장이 발생하지 않는 경우에도 부품의 신뢰성을 평가할 수 있는 유용한 수단이 되고 있다. 본 연구에서는, 능동소자로 높은 유전용량을 갖는 적층 세라믹 콘덴서(X7R -55$^{\circ}C$~1$25^{\circ}C$)에 대한 가속열화시험을 실시하고, 정격온도의 최대치에서 다른 배율의 전압을 인가하여 단순선형회귀에 의한 특성치의 경시변화를 설명한다고 가정하였다. 최소제곱법을 적용하여 시료가 대수정규분포를 따를 때의 열화량을 설명한 후, 특성치-시간간의 선형관계 및 대수정규분포의 독립성을 검정하여 가정의 적절성을 검정하였다. 마지막으로 아이링모델에 의한 평균수명을 평가하였다.