• Title/Summary/Keyword: True Stress

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Quality-Sustainable Way to Business Excellence

  • Kondo, Yoshio
    • International Journal of Quality Innovation
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    • v.3 no.2
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    • pp.1-12
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    • 2002
  • Quality is distinguished from the other important management indicators, cost and profitability, by the features of its far longer history and of common concern to both manufacturer and customer. We may say from this that quality has a far more human aspect than either cost or profitability. We stress the importance of establishing “quality culture.” But we do not commonly use the terms of “cost culture” or “productivity culture.”In addition, we know from our experiences that improving quality by creative methods can lead to lower cost and higher productivity, although the converse is not necessarily true. In the Maslow's hierarchy of human needs, it is known that the character of human needs changes from extrinsic and material ones at lower levels to intrinsic and mental or spiritual ones at higher levels. We know from our experience that employee satisfaction is closely linked with quality, which is of more human nature and can further be deployed into the detailed elements of quality. The leaders and managers should positively display leadership and respond to the efforts of the subordinates. Without these managerial leadership and efforts, it is almost impossible to provide essential and true customer satisfaction. They are the indispensable elements for business excellence.

High Temperature Deformation Behavior of Al-Zn-Mg-Based New Alloy Using a Dynamic Material Model

  • Jang, Bong Jung;Park, Hyun Soon;Kim, Mok-Soon
    • Metals and materials international
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    • v.24 no.6
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    • pp.1249-1255
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    • 2018
  • High temperature compression tests for newly developed Al-Zn-Mg alloy were carried out to investigate its hot deformation behavior and obtain deformation processing maps. In the compression tests, cylindrical specimens were deformed at high temperatures ($300-500^{\circ}C$) and strain rates of 0.001-1/s. Using the true stress-true strain curves obtained from the compression tests, processing maps were constructed by evaluating the power dissipation efficiency map and flow instability map. The processing map can be divided into three areas according to the microstructures of the deformed specimens: instability area with flow localization, instability area with mixed grains, and stable area with homogeneous grains resulting from continuous dynamic recrystallization (CDRX). The results suggest that the optimal processing conditions for the Al-Zn-Mg alloy are $450^{\circ}C$ and a strain rate of 0.001/s, having a stable area with homogeneous grains resulting from CDRX.

Development of Textures and Microstructures during Compression in a Hot-Extruded AZ31 Mg Alloy (고온압출한 AZ 31 마그네슘 합금의 압축변형 중 집합조직과 미세조직의 발달)

  • Jung, Byung Jo;Lee, Myung Jae;Park, Yong-Bum
    • Korean Journal of Metals and Materials
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    • v.48 no.4
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    • pp.305-314
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    • 2010
  • The development of textures and microstructures during plastic deformation in a hot-extruded AZ 31 Mg alloy was investigated using a compression test with such parameters as deformation temperature, strain rate. It was observed from true stress-strain curves that twinning involves changes of the flow stresses. In the early stages of deformation at temperatures lower than $200^{\circ}C$, the occurrence of twins resulted in a decrease of the work-hardening rate, which increased drastically at a true strain of -0.05. The evolution of the deformation textures were assessed with the aid of EBSD analyses in terms of the competition between twinning and slip activity.

Src Protein Tyrosine Kinases in Stress Responses

  • Grishin, Anatoly;Corey, Seth J.
    • Animal cells and systems
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    • v.6 no.1
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    • pp.1-12
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    • 2002
  • A role of Src family protein Tyrosine kinases (SFK) as mediators of receptor-ligand initiated responses is well established. Well documented, but less well understood is the role of SFK in cellular reaction to stresses. Evidence from the wide variety of experimental systems indicates that SFK mediate responses to all major classes of stress, including oxidation, DNA damage, mechanical impacts, and protein denaturing. SFK may be activated by stresses directly or via regulatory circuits whose identity is not yet fully understood. Depending on the cell type and the nature of activating stimulus, SFK may activate known downstream signaling cascades leading to cell survival, proliferation, cytoskeletal rearrangement, and apoptosis; the identity of these cascades is discussed. As in the case of receptor-initiated signaling, roles of individual SFK in various stress response may be redundant or non-redundant. Although signals generated by different stresses are generally transduced via distinct SFK pathways, these pathways may overlap or exhibit crosstalk. In some cell types stress-induced activation of SFK promotes survival and inhibits apoptosis, whereas the opposite may be true for other cell types. Stress responses constitute a new and rapidly developing area of SFK-mediated signaling.

Development of Evaluation Technology of Mechanical Properties Using Continuous Indentation Method (연속압입시험법을 이용한 소재의 기계적 물성 평가기술 연구)

  • Lee, Jeong-Hwan;Ok, Myoung-Ryul;Lee, Yun-Hee;Ahn, Jeong-Hoon;Kwon, Dong-Il
    • Proceedings of the KIEE Conference
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    • 1997.11a
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    • pp.703-708
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    • 1997
  • Continuous indentation test is a very powerful method to monitor the materials reliability since it is very simple, easy and almost non-destructive. It can provide material properties such as elastic modulus, yield strength, work-hardening exponent, etc., than the conventional hardness test. In our study, the true stress-strain curve is derived from the indentation load-depth curve. For this, average indentation strain is defined and the flow stress is obtained from the analysis of the indentation stress field. The residual stress is analyzed from the variation of the indentation behavior with the applied residual stress. And the estimation of fracture characteristic is tried by considering the conventional fracture toughness modeling and the stress/strain state under the spherical indenter.

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The Linkage between Emotional Labor and Stress Effects on Retail Sales Workers

  • KIM, Jina;JUNG, Hye-Sun
    • Journal of Distribution Science
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    • v.19 no.10
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    • pp.99-109
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    • 2021
  • Purpose: Retail workers have a role in attending to customers better, not only making sales to them. In this regard, this research focuses on having a clear understanding of the effects of emotional factors and job stress on mental health for retail sales workers. Research design, data and methodology: The present research conducted both a qualitative textual analysis and interview. This research method is quite useful because it relates the information collected with the research gap. Qualitative data is time-consuming type of data to analyze since it involves interpreting words rather than numbers. Results: The findings showed that emotional labor and stress may not only cause mental harm to the employees but can result in adverse reaction to the customers. Retail employees need to express their true emotions and avoid pretending to be helped with a clear understanding of their needs. Conclusion: This study conclude that motional labor and stress to the retail workers is a real issue that has affected many people around the globe and there is a need to conduct more research on the issue to help employees serve customers much better. Stress among sales workers results to poor working morale and thus affects the entire organization at large.

Modified 𝜃 projection model-based constant-stress creep curve for alloy 690 steam generator tube material

  • Moon, Seongin;Kim, Jong-Min;Kwon, Joon-Yeop;Lee, Bong-Sang;Choi, Kwon-Jae;Kim, Min-Chul;Han, Sangbae
    • Nuclear Engineering and Technology
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    • v.54 no.3
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    • pp.917-925
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    • 2022
  • Steam generator (SG) tubes in a nuclear power plant can undergo rapid changes in pressure and temperature during an accident; thus, an accurate model to predict short-term creep damage is essential. The theta (𝜃) projection method has been widely used for modeling creep-strain behavior under constant stress. However, many creep test data are obtained under constant load, so creep rupture behavior under a constant load cannot be accurately simulated due to the different stress conditions. This paper proposes a novel methodology to obtain the creep curve under constant stress using a modified 𝜃 projection method that considers the increase in true stress during creep deformation in a constant-load creep test. The methodology is validated using finite element analysis, and the limitations of the methodology are also discussed. The paper also proposes a creep-strain model for alloy 690 as an SG material and a novel creep hardening rule we call the damage-fraction hardening rule. The creep hardening rule is applied to evaluate the creep rupture behavior of SG tubes. The results of this study show its great potential to evaluate the rupture behavior of an SG tube governed by creep deformation.

A Study on the Job Stress Factors according to the Working Years of School Food Service Nutritionists in Gangwon Area (강원 지역 학교 급식 영양사의 근무 년수에 따른 직무스트레스 요인에 관한 연구)

  • Noh, Mi-Ah;Kim, Ji-Sang;Lee, Young-Soon
    • Journal of the Korean Society of Food Culture
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    • v.24 no.6
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    • pp.728-738
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    • 2009
  • The purpose of this study was to evaluate job stress factors of school food service nutritionists according to the number of years they have worked. The subjects of this survey included 125 nutritionists (69 from full-time employees and 56 from part-time nutritionists) from elementary school, middle school, and high school in the Gangwon area. The results showed that stress related to duty was the top job stress factor, followed by environment-related stress, personal stress, organization-related stress and stress caused by human relations. In terms of the degree of stress, part-time nutritionists have more stress compared to full-time nutritionists. This was especially true for nutritionists that had been employed for one year. In this case, the degree of stress was much higher than long time employed nutritionists. In terms of how to deal with job stress, school nutritionists eliminated stress directly (with direct countermeasures). In order to deal with stress, workers expected stable employment such as pay (wages), promotions, etc. In particular, part-time school nutritionists had stronger expectations. When correlation between job stress factors were examined, environment-related, duty-related, organization-related, human relations-related and personal stress were all shown to be mutually related.

Improvement of Measurement Accuracy by Correcting Systematic Error Associated with the X-ray Diffractometer (X-선 회절 장비의 기계적 오차 수정을 통한 분석 정확도 향상)

  • Choi, Dooho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.97-101
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    • 2017
  • X-ray diffractometers are used to characterize material properties, such as the phase, texture, lattice constant and residual stress, based on the diffracted beams obtained from specimens. Quantitative analyses using X-rays are typically conducted by measuring the peak positions of the diffracted beams. However, the long-term use of the diffractomer, like any other machine, results in errors associated with the mechanical parts, which can deteriorate the accuracy of the quantitative analyses. In this study, the process of correcting systematic errors in the $2{\theta}$ range of $30{\sim}90^{\circ}$ is discussed, for which strain-free Si powders from NIST were used as the standard specimens. For the evaluation of the impact of such error correction, we conducted a quantitative analysis of the true lattice constant for tungsten thin films.

On the Conditional Tolerance Probability in Time Series Models

  • Lee, Sang-Yeol
    • Journal of the Korean Statistical Society
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    • v.26 no.3
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    • pp.407-416
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    • 1997
  • Suppose that { $X_{i}$ } is a stationary AR(1) process and { $Y_{j}$ } is an ARX process with { $X_{i}$ } as exogeneous variables. Let $Y_{j}$ $^{*}$ be the stochastic process which is the sum of $Y_{j}$ and a nonstochastic trend. In this paper we consider the problem of estimating the conditional probability that $Y_{{n+1}}$$^{*}$ is bigger than $X_{{n+1}}$, given $X_{1}$, $Y_{1}$$^{*}$,..., $X_{n}$ , $Y_{n}$ $^{*}$. As an estimator for the tolerance probability, an Mann-Whitney statistic based on least squares residuars is suggested. It is shown that the deviations between the estimator and true probability are stochatically bounded with $n^{{-1}$2}/ order. The result may be applied to the stress-strength reliability theory when the stress and strength variables violate the classical iid assumption.umption.n.

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