• Title/Summary/Keyword: Equivalent life

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A Study on the Estimation of the Fatigue Life Using the Stress Generated Models in the Steel Railroad Bridges (강철도교의 응력발생모형을 이용한 피로수명 추정에 관한 연구)

  • Yong, Hwan Sun;Kim, Seok Tae;Lee, Seong Soo
    • Journal of Korean Society of Steel Construction
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    • v.8 no.4 s.29
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    • pp.19-29
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    • 1996
  • In this paper, it is presumed that the stress time history was generated by simulation method and investigated compatibility in regard to the reappearance of stress time history. In this procedure, the identified frequency distribution of stress range of the steel railroad bridge varies with the rational values of cut off point and bar width. Thus, we show variable aspect of the equivalent stress range results from change of cut off point and bar width. In addition, we analyze the variable of RMC and RMS model due to the cut off point and bar width of the measured stress history which influencs the prediction of fatigue life in the steel railroad bridge. The simulated stress time history is carried out by the superposition method incorporating the vertical load with rotation moment obtained from the Hermition interpolation function, and compared with developing stress results from measured maxi mum stress. Through this study, we can estimate the remaining fatigue life from a safety point of view and comparative accuracy.

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Effects of Friction Coefficient on Creep Life Assessment of Sheet (박판 크리프 수명평가에 마찰계수의 영향)

  • Jeong, J.Y.;Im, J.W.;Keum, Y.T.
    • Transactions of Materials Processing
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    • v.19 no.7
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    • pp.435-440
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    • 2010
  • The creep life of 9Cr1MoVNb steel, in terms of Larson-Miller parameter(LMP), was evaluated by small punch(SP) creep simulation and verified by uniaxial creep test. By employing the elastoplastic FEM(finite element method), the small punch creep behaviors associated with various friction coefficients were simulated to identify a real friction phenomena. The friction coefficient, ${\mu}$=0.7, determined by comparing deflection history was used in the small punch creep simulation to find the equivalent stresses with which the relationship between punch load and uniaxial creep stress was found. The creep life was then predicted by the LMP, which was the relationship among the rupture time, temperature, and stress. Finally, the LMP calculated by SP-creep simulation was compared with that had computed by the uniaxial creep test and fairly matched LMPs were found.

A New Compressive Testing Specimen for Linerboard and Corrugating Medium (ECT를 응용한 라이너지의 압축강도 측정시편 개발)

  • Youn, Seuk-Ki;Seo, Yung-Bum;Jeon, Yang
    • Korean Journal of Agricultural Science
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    • v.35 no.1
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    • pp.19-24
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    • 2008
  • A new compressive strength test specimen for linerboard and medium was developed, and tested for its agreement with conventional testing methods such as RCT and STFI. The new specimen enables compressive testing under the changing humidity and temperature. Experimental results showed that the new specimen gave equivalent compressive strengths as the other conventional methods at a constant temperature and humidity. We'll apply the methods under the cyclic humidity and temperature conditions.

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A Proposal of parameter Determination Method in the Residual Strength Degradation Model for the Prediction of Fatigue Life(II) (피로수명예측을 위한 잔류강도 저하모델의 파라미터 결정법 제안(II))

  • Kim, Sang-Tae;Jang, Seong-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.9
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    • pp.1452-1460
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    • 2001
  • A new method of parameter determination in the fatigue residual strength degradation model is proposed. The new method and minimization technique is compared experimentally to account for the effect of tension-compression fatigue loading of spheroidal graphite cast iron and graphite/epoxy laminate. It is shown that the correlation between the experimental results and the theoretical prediction on the fatigue life and residual strength distribution using the proposed method is very reasonable. Therefore, the proposed method is more adjustable in the determination of the parameter than minimization technique for the prediction of the fatigue characteristics.

The cost efficiency analysis of Korean life insurance companies by data envelopment analysis

  • Kang, Jungchul
    • Journal of the Korean Data and Information Science Society
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    • v.26 no.6
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    • pp.1523-1535
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    • 2015
  • We investigate the effect of introduction of the bancassurance system on cost efficiency in the Korean insurance industry between 1997 and 2012. Our estimation results indicate that introduction of this system contributed positively to efficiency of life insurance companies in Korea. Increase in a one standard deviation of bancassurance increases cost efficiency by 0.08 which is equivalent to 12 percent of mean cost efficiency. Recognising that the bancassurance system is a relatively new concept, our results indicate that the bancassurance system can be a policy measure to improve productivity in an emerging insurance market. The results illustrate that positive effects have accrued particularly to medium-sized companies and domestic companies, contrary to the prevailing perception that increased competition through bancassurance is more beneficial to large companies and foreign companies.

An Evaluation of Fatigue Life for Aging Aircraft Structure (장기운용항공기 구조물의 잔여 피로수명예측 기법)

  • Lee, Eungyeong;Jeong, Yooin;Kim, Sangshik
    • Korean Journal of Materials Research
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    • v.25 no.10
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    • pp.516-522
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    • 2015
  • Aging aircraft structures are inevitably exposed to environment for a long time facing many potential problems, including corrosion and wide spread fatigue damage, which in turn cause the degradation of flight safety. In this study, the environmental surface damages on aging aircraft structures induced during service were quantitatively analyzed. Additionally, S-N fatigue tests were performed with center hole specimens extracted from aging aircraft structures. From the results of quantitative analyses of the surface damages and fatigue tests, it is concluded that corrosion pits initiated during service reduce the fatigue life significantly. Finally, using the fracture mechanics and the EIFS (equivalent initial flaw size) concepts, the remaining fatigue life was predicted based on actual fatigue test results.

Flower-Inducing Activity in the Phloem Exudata and Gene Expression Specific to Photoperiodic Floral Induction in Pharbitis Cotyledons

  • Kim, Kang-Chang;Lee, Jin-Hwan;Her, Yoon-Kang;Maeng, Jue-Son
    • Journal of Plant Biology
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    • v.39 no.4
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    • pp.257-263
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    • 1996
  • Flower-inducing activity in the phloem exudata of Pharbitis cotyledons was investigated using the bioassay of Pharbitis and Lemna. By SDS-PAGE and 2-D gel electrophoresis of the phloem exudate, two polypeptides of 11 kDa and of approximately 32 kDa (pI 6.9) showing qualitative changes during the flower induction were detected. A polypeptide of approximately 20 kDa (pI 4.8) specifically labeled in vivo with [35S]methionine was found during the inductive dark period in Pharbitis cotyledon tissues. The polypeptide of the equivalent molecular mass and with the identicl pI value was also detected by in vitro translation assay. Thus, it is assumed that the 20 kDa polypeptide plays a role in the process of flower induction in Pharbitis cotyledons.

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Effects of a Hospice and Palliative Care Education Program Including Meaning in Life on Attitudes Toward End-of-Life Care and Meaning in Life Among Nursing College Students (의미요법이 포함된 호스피스·완화 간호교육이 간호대학생의 임종간호태도와 생의 의미에 미치는 효과)

  • Kim, Sook-Nam;Kim, Hyun-Ju;Choi, Soon-Ock
    • The Journal of Korean Academic Society of Nursing Education
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    • v.17 no.3
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    • pp.454-463
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    • 2011
  • Purpose: The purpose of this study was to examine the effects of a hospice and palliative care education program including meaning in life on attitudes to end-of-life care and meaning in life for nursing students. Methods: This study used a quasi-experimental and non- synchronized with a non-equivalent control group design. The experimental group (n=28) participated in a hospice and palliative care education program including meaning in life. The control group (n=28) participated only in a hospice and palliative care education program. The 30-hour course examined hospice and palliative nursing care and logotherapy. Data were collected using a structured questionnaire consisting of general characteristics, attitudes to end-of-life care, and meaning in life. Collected data were analyzed for frequency, percentage, ${\chi}^2$-test, and t-test using SPSS 19.0 WIN Program. Results: Scores for the attitude towards end-of-life care in the experimental group were significantly higher than in the control group. The meaning in life scores in the experimental group were significantly higher than in the control group. Conclusion: These findings suggest that the hospice and palliative care education program, including meaning in life, was effective in enhancing the attitude to end-of-life care and meaning in life among nursing students.

Effects of the Sex Education Program on Elders' Sex Perception and Life Satisfaction (성교육 프로그램이 노인의 성인식과 삶의 만족도에 미치는 영향)

  • Park, Gong-Ju;Jung, Hyang-Mi
    • The Korean Journal of Health Service Management
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    • v.8 no.3
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    • pp.181-192
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    • 2014
  • The purpose of this study was to evaluate the effect of a sex education program on the aged's sex perception and the life satisfaction. It was the non-equivalent control group pre-post test design, the number of subjects was 65 people as the experimental group and 70 people as the control group over 65 the aged. The program was conducted for 80 minutes a time for 6times of the N settlement house in P city from August 25 to September 16 in 2011. The study tool which was developed by Lee(1999) and revised by Jeong(2007), was used to measure the sex perception. The life satisfaction was measured by Naugarten(1961) and modified by Kim(2002). The date were analyzed as SPSS Win 17.0, the percentage, t-test, and the hypothesis was analyzed as t-test. The experimental group got higher scores on the sexual percetion(t=3.816, p<.001) and the life satisfaction(t=4.594, p<.001). This program is for generalized that must be performed in a repeat and comprehensive study with the many aged.

Effects on Stress, Problem Solving Ability and Quality of Life of as a Stress Management Program for Hospitalized Schizophrenic Patients: Based on the Stress, Appraisal-Coping Model of Lazarus & Folkman (Lazarus와 Folkman의 스트레스 평가-대처 모델에 근거한 입원 스트레스 관리 프로그램이 조현병 환자의 스트레스, 문제해결능력 및 삶의 질에 미치는 영향)

  • Park, Sun Ah;Sung, Kyung Mi
    • Journal of Korean Academy of Nursing
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    • v.46 no.4
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    • pp.583-597
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    • 2016
  • Purpose: The study was done to evaluate the effects a Stress Management Program (SMP) on stress, problem solving skills, and quality of life for hospitalized patients with Schizophrenia. Methods: A mixed method design was used: a combination of a repeated-measure design with a non-equivalent control group and qualitative data collection. The participants were 40 patients with schizophrenia admitted in three psychiatric hospitals. The experimental group (n=20) received the SMP twice a week for a total of 8 weeks. Results: Study results revealed that the SMP was effective for stress (F=321.02, p<.001), problem solving ability (F=246.28, p<.001), and quality of life (F=63.35, p<.001) for hospitalized persons with schizophrenia. Conclusion: The results suggest that a SMP can be an effective strategy to reduce patients' hospitalization stress, and improve problem solving skills and quality of life. Therefore, it is recommended that mental health nurses use this stress management program in clinical practice to assist adaptation to hospitalization for persons with schizophrenia.