• Title/Summary/Keyword: Loading cycles

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A Scale for Clothing Satisfaction: A Consumer Life Cycle Approach (의복만족 척도: 소비자 생활주기적 접근)

  • Jeon, Kyung-Sook;Park, Hye-Jung
    • Journal of the Korean Society of Clothing and Textiles
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    • v.33 no.7
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    • pp.1050-1060
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    • 2009
  • This study develops a scale for consumer clothing satisfaction based on Lee et al. 's (2002) five stages of the consumer life cycle (acquisition, possession, consumption, maintenance, and disposal). Data were gathered by surveying college students using convenience sampling, and 419 questionnaires were used in the statistical analysis. In analyzing the data, an exploratory factor analysis and a confirmatory factor analysis using a structural equation modeling were conducted. The proposed scale, which identified various sources of satisfaction and dissatisfaction associated with the 5 consumption cycles of clothing, suggests some guidelines for marketers in enhancing consumer clothing satisfaction across consumption stages. The model test for the scale also identified that consumption satisfaction had the greatest effect on consumer clothing satisfaction showing the strongest loading and squared multiple correlation.

LOW CYCLE THERMAL FATIGUE OF THE ENGINE EXHAUST MANIFOLD

  • Choi, B.L.;Chang, H.;Park, K.H.
    • International Journal of Automotive Technology
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    • v.5 no.4
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    • pp.297-302
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    • 2004
  • This paper presents the low cycle thermal fatigue of the engine exhaust manifold subject to thermo-mechanical cyclic loading. As a failure of the exhaust manifold is mainly caused by geometric constraints of the less expanded inlet flange and cylinder head, the analysis is based on the exhaust system model with three-dimensional temperature distribution and temperature dependent material properties. The result show that large compressive plastic deformations are generated at an elevated temperature of the exhaust manifold and tensile stresses are remained in several critical zones at a cold condition. From the repetition of these thermal shock cycles, maximum plastic strain range (0.454%) could be estimated by the stabilized stress-strain hysteresis loops. It is used to predict the low cycle thermal fatigue life of the exhaust manifold for the thermal shock test.

THE INVESTIGATION OF PSEUDOELASTIC NITI WIRES FOR DAMPING USES

  • Pan, Qiang;Cho, Chong-Du;Lu, Sheng
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.154-159
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    • 2007
  • Some shape memory alloys like NiTi show noticeable high damping property in pseudoelastic range. Due to its instinct characteristics, a NiTi alloy is commonly used for passive damping applications, in which the energy may be dissipated by the conversion from mechanical to thermal energy. Previous researches found the NiTi wires own higher damping property than the bars; therefore the wire form is adopted in this study. A loss factor is introduced for measuring the damping property of the NiTi wires. The experimental observation shows the mechanical behaviors of NiTi wires are dependent on temperature, strain rate and strain amplitude. Moreover, it is found the first several decades of loading-unloading cycles can obviously influence the property of NiTi wires under the same working conditions.

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Fatigue Crack Propagation Analysis by P-version of Finite Element Method (P-Version 유한요소법에 의한 피로 균열 해석)

  • 우광성;이채규
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1992.04a
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    • pp.30-35
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    • 1992
  • Since many design problems in the railroad, aerospace and machine structures involve considerations of the effect of cyclic loading, manufacturing and quality control processes must fully account for fatigue of critical components. Due to the sensitivity of the Paris law, it is very important to calculate the ΔK numerically to minimize the error of predicted fatigue life in cycles. It is shown that the p-version of FEM based on LEFM analysis is far better suited for computing the stress intensity factors than the conventional h-version. To demonstrate the proficiency of the proposed scheme, the welded T-joint with crack problem of box car body bolster assembly and a crack problem emanating Iron a circular hole in finite strip have been solved.

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Interpretation of Stress Crack Resistance of Damaged Geomembranes (손상된 지오멤브레인의 응력균열 저항성 해석)

  • Jeon, Han-Yong;Kahn, Belas Ahmed;Jang, Yeon-Soo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.305-313
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    • 2010
  • HDPE smooth and textured GMs were cut into dumbbell shape and notched where depth of the notch produced a ligament thickness of 90% to 10% of the nominal thickness of the specimen at 10% interval. Yield stress and elongation were measured of those samples and plotted on Graph. Yield stress and elongation at yield point decreases gradually as the notch depth is increased. Both installations damaged and notched GMs were used to understand stress crack behavior. Intact sample were notched in such a manner that the depth of notch produced a ligament thickness of 80% of the nominal thickness of the specimen. Installation damaged samples were not notched. Stress Crack Resistance behavior was observed using NCTL Test at $50{\pm}1^{\circ}C$ at different yield stresses immerging with pH 4 and pH 12 buffer solutions. Significant difference was observed in both cases.

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Cyclic Threshold Shearing Strains of Sands Based on Pore Water Pressure Buildup and Variations of Deformation Characteristics (간극수압증가와 동적변형특성 변화에 근거한 사질토 지반의 반복한계전단변형률)

  • Kim, Dong-Soo;Choo, Yun-Wook
    • Proceedings of the Korean Geotechical Society Conference
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    • 2004.03b
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    • pp.274-281
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    • 2004
  • In this paper, the existing Stokoe type torsional shear equipment is modified to saturate the specimen and measure excess pore water pressure during undrained testing. Two types of sands, Geumgang and Toyoura sands, were collected and TS tests were performed at various densities drainage conditions, and confining pressures. The cyclic threshold shearing strains were estimated based on the variations of shear modulus, material damping ratio and pore pressures with loading cycles. The effects of relative density, confining pressure, and drainage condition on the cyclic threshold shearing strains were investigated.

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Growth of magnesium oxide nanoparticles onto graphene oxide nanosheets by sol-gel process

  • Lee, Ju Ran;Koo, Hye Young
    • Carbon letters
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    • v.14 no.4
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    • pp.206-209
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    • 2013
  • Nanocomposites comprised of graphene oxide (GO) nanosheets and magnesium oxide (MgO) nanoparticles were synthesized by a sol-gel process. The synthesized samples were studied by X-ray powder diffraction, atomic force microscopy, transmission electron microscopy, and energy-dispersive X-ray analysis. The results show that the MgO nanoparticles, with an average diameter of 70 nm, are decorated uniformly on the surface of the GOs. By controlling the concentration of the MgO precursors and reaction cycles, it was possible to control the loading density and the size of the resulting MgO particles. Because the MgO particles are robustly anchored on the GO structure, the MgO/GOs nanocomposites will have future applications in the fields of adsorption and chemical sensing.

A Probabilistic Analysis for Fatigue Cumulative Damage and Fatigue Life in CFRP Composites Containing a Circular Hole (원공을 가진 CFRP 복합재료의 피로누적손상 및 피로수명에 대한 확률적 해석)

  • 김정규;김도식
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.8
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    • pp.1915-1926
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    • 1995
  • The Fatigue characteristics of 8-harness satin woven CFRP composites with a circular hole are experimentally investigated under constant amplitude tension-tension loading. It is found in this study that the fatigue damage accumulation behavior is very random and history-independent, and the fatigue cumulative damage is linearly related with the mean number of cycles to a specified damage state. From these results, it is known that the fatigue characteristics of CFRP composites satisfy the basic assumptions of Markov chain theory and the parameter of Markov chain model can be determined only by mean and variance of fatigue lives. The predicted distribution of the fatigue cumulative damage using Markov chain model shows a good agreement with the test results. For the fatigue life distribution, Markov chain model makes similar accuracy to 2-parameter Weibull distribution function.

용접부 쉐브론노치 형상에 대한 균열전파 특성

  • 김엽래
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1996.10a
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    • pp.194-197
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    • 1996
  • The high-strength aluminum alloy 7075-T651 was used to observe the fatigue-crack-propagation behavior for the various stress ratios with constant amplitude loading and thus to predict the fatigue life. With a chevron notch in the specimen the fatigue-crack-propagation behavior of through crack was investigated. Crack propagation behavior of through crack in the depth direction and crack growth of weldments were experimentally studied. Base material heat affected zone and weld material were considered in the fracture of weldments. The change of crack-propagation length with respect to several parameters such as stress intensity factor range(ΔK) effective stress intensity factor range(ΔKeff)ration of effective stress intensity factor range(U) stress intensity factor of crack opening point(K op) maximum stress intensity factor(K max) and number of cycles(Nf)was determined. The crack length of through crack of weldments was 2.4mm and the remaining part was a base material. The experiment was accomplished by making the crack propagate near the base material.

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Prediction of terminal density through a two-surface plasticity model

  • Won, Jongmuk;Kim, Jongchan;Park, Junghee
    • Geomechanics and Engineering
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    • v.23 no.5
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    • pp.493-502
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    • 2020
  • The prediction of soil response under repetitive mechanical loadings remains challenging in geotechnical engineering applications. Modeling the cyclic soil response requires a robust model validation with an experimental dataset. This study proposes a unique method adopting linearity of model constant with the number of cycles. The model allows the prediction of the terminal density of sediments when subjected to repetitive changes in pore-fluid pressure based on the two-surface plasticity. Model simulations are analyzed in combination with an experimental dataset of sandy sediments when subjected to repetitive changes in pore fluid pressure under constant deviatoric stress conditions. The results show that the modified plastic moduli in the two-surface plasticity model appear to be critical for determining the terminal density. The methodology introduced in this study is expected to contribute to the prediction of the terminal density and the evolution of shear strain at given repetitive loading conditions.