• 제목/요약/키워드: Long Life Test

검색결과 614건 처리시간 0.027초

열화에 따른 파괴인성치의 연성-취성 천이거동 평가 (Evaluation of the Ductile-Brittle Transition Behavior of fracture Toughness by Material Degradation)

  • 석창성;김형익;김상필
    • 한국정밀공학회지
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    • 제20권5호
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    • pp.140-147
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    • 2003
  • As the huge energy transfer systems like as nuclear power plant and steam power plant are operated for a long time at a high temperature, mechanical properties are changed and ductile-brittle transition temperature is raised by degradation. So it is required to estimate degradation in order to assess the safety, remaining life and further operation parameters. The sub-sized specimen test method using surveillance specimen was developed for evaluating the integrity of metallic components. In this study, we would like to present the evaluation technique of the ductile-brittle transition temperature by the sub-sized specimen test. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. The tensile test and fracture toughness test were performed. The results of the fracture toughness tests using the sub-sized specimens were compared with the evaluation technique of the ductile-brittle transition temperature.

재료열화에 따른 파괴인성치의 연성-취성 천이거동 평가 (The Evaluation of Ductile-Brittle Transition of Fracture Toughness by Material Degradation)

  • 김상필;김형익;석창성
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집A
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    • pp.579-584
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    • 2001
  • As the huge energy transfer systems like as nuclear power plant and steam power plant are operated for a long time, mechanical properties are changed and ductile-brittle transition temperature is raised by degradation. So it is required to estimate degradation in order to assess the safety, remaining life, and further operation parameters. The sub-sized specimen test method using surveillance specimen was developed for evaluating the integrity of metallic components. In this study, we would like to present the evaluation technique of the ductile-brittle transition temperature by the sub-sired specimen test. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. The tensile test and fracture toughness test were performed. The results of the fracture toughness tests using the sub-sized specimens were compared with the evaluation technique of the ductile-brittle transition temperature.

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자기효능ㆍ희망증진프로그램이 자기간호 행위와 삶의 질에 미치는 효과 -백혈병 환자 중심- (Effects of a Program to Promote Self-Efficacy and Hope on the Self-Care Behaviors and the Quality of Life in Patients with Leukemia)

  • 오복자;이은옥;태영숙;엄동춘
    • 대한간호학회지
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    • 제27권3호
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    • pp.627-638
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    • 1997
  • Most patients having leukemia suffer severely from emotional turmoil due to the generalized perception that cancer will be fatal. The conventional chemotherapy results in side effects such as severe bone marrow depression which interfere with self-care management, vital for improvement in their condition. Bandura's theory of the self-efficacy suggests that self- efficacy can be enforced by performance attainments, vicarious experiences, verbal per-suasion and the release of emotional arousal. Self-efficacy can be enforced by a program of vicarious experiences and verbal persuasion, while the emotional arousal can be relieved through a hope promotion program, If once self-efficacy increases, the patient's self-care behaviors and the quality of life will also increase. The purpose of this study was to empirically test the effects of a program, to promote self-efficacy and hope, on self-care behaviors and quality of life in patients having leukemia. In this study, three types of approaches to enhance self-efficacy and hope were used : 1) a 20-minute long slide /tape for vacarious experiences : 2) a 10-minute long telephone call coaching for verbal persuasion ; and 3) two booklets for information about the symptoms of leukemia and treatment modalities and hope promotion. Thirty one patients were recruited in the experimental group and 29 in the control group with a nonequivalent pretest-posttest design. The subjects were patients with leukemia undergoing chemotherapy. Sherer and Maddux's self-efficacy scale, Nowotny's hope scale, and Padilla's quality of life scale were employed with some modifications. A self-care behavior scale was developed by the researchers. Statistical analyses including paired t-test, Chi-square, ANCOVA and ANOVA, were used. The results are as follows : The levels of self-efficacy, self-care behavior and quality of life were higher in the experimental group than in the control group after four weeks of intervention(F=28.71, P=.0001 ; F=63.35, P=.0001 F=16.57, P=.0001). After ten weeks of intervention, all of the dependent variables(self-efficacy, self-care behavior, hope & quality of life) in the experimental group were higher than in the control group (F=74.12, P=.0001 ; F=108.34, P=.0001 ; F=13,11, P=.001 : F=43.52, P=.0001). In conclusion, self-care behavior and quality of life increased mainly through an increase in self-efficacy, while increases in hope took more time and effort.

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경상남도 웰니스관광의 염증면역지표, 자율신경균형, 정서, 피로, 스트레스, 삶의 질 및 수면의 질 개선에 미치는 단기효과 (Short-term Effect of Gyeongsangnam-do Wellness Tourism on Inflammatory and Immune System Markers, Emotion, Fatigue, Stress, Quality of Life, and Quality of Sleep)

  • 이새롬;이예리;이상엽
    • 대한통합의학회지
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    • 제9권3호
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    • pp.19-35
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    • 2021
  • Purpose : Recently, there has been a growing social interest in aging well. Consequently, wellness tourism has begun to attract attention. However, no studies on whether wellness tourism has any objective health benefits have been carried out yet. In this study, we assess the health benefits as well as the degree of improvement in health of a wellness tourism program. Methods : The study involved 30 adults over the age of 19 who live in the Gyeongsangnam-do region. Participants were evaluated on health indicator before and after participating in wellness tourism program. Participants took heart rate variability (HRV) test, and LFT, RFT, CBC, FBS HbA1C, and CRP test were conducted before and after the tour. Additionally, a survey was conducted before and after the program, and participant satisfaction was evaluated. Statistical differences in the tests conducted before and after the program were analyzed using a design t-test, a Wilcoxon signed-rank test, and McNemar's test. Results : The study showed that participants were very satisfied with and had significant health improvements after the wellness tourism program. The program was also found to be beneficial in improving participants' emotions as follows: BDI (p<.001), fatigue recovery (p=.006), stress relief (p=.003), improved quality of life (p<.05), and improved sleep quality (p<.001). Conclusion : Wellness tourism programs are specifically beneficial for improving participants' emotions (depression, anxiety), fatigue, stress levels, quality of life, and sleep. Therefore, they are beneficial to the overall health. Further research in the future by way of a follow-up study on the long-term effects on health after short-term interventions will provide more validation data.

자가 조혈모세포 이식환자와 동종 조혈모세포 이식환자의 삶의 질의 비교 (Comparison of Quality of Life of Autologous and Allogeneic Hematopoietic Stem Cell Transplantation Recipients)

  • 김은지
    • 종양간호연구
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    • 제8권1호
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    • pp.50-60
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    • 2008
  • Purpose: The purpose of this study was to compare Quality of life (QOL) in type and time after Hematopoietic stem cell tansplantation (HSCT) for patients with hematologic cancer. Method: This study was cross-sectional. The autologous recipients was 120, the allogeneic recipients was 237. The obtained data were analyzed using T-test, One-way ANOVA, Scheffe's test. Results: No significant differences were total QOL between the autologous and allogeneic recipients. But the autologous recipients reported better status than the allogeneic recipients in physical domain, especially 1-3 yr after HSCT. There was poorer QOL of 1-3 yr compared to 1 yr after HSCT in physical, psychological and social domain between the two groups. QOL in time after HSCT of the autologous recipients was significance differences in psychological, social domain. And QOL in time after HSCT of the allogeneic recipients was significant differences in physical, psychological and social domain. Conclusions: QOL of recipients undergoing HSCT is recovered beyond 3 yr point. Accordingly, long term care and service is essential to recipients undergoing HSCT. And further studies with a longitudinal design are necessary.

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요양병원 입원 노인환자의 구강건강인식도와 구강건강관련 삶의 질에 관한 연구 (A study on oral health perception and oral health-related quality of life of the elderly patients in a geriatric hospital)

  • 김가현;권용선
    • 한국치위생학회지
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    • 제16권3호
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    • pp.363-371
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    • 2016
  • Objectives: The purpose of the study was to investigate the relationship between oral health perception and oral health-related quality of life-14(OHIP-14) in a geriatric hospital. Methods: A self-reported questionnaire was completed by 230 elderly people in a long-term care institution. The questionnaire was consisted of items on general characteristics, oral health perception and OHIP-14. Except incomplete answers, 226 data were analyzed statistically with one-way ANOVA, t-test, Pearson's correlation coefficient and post hoc Tukey test and ANOVA when significance was set at 0.05. Results: The OHIP-14 showed a negative linear relationship(p<0.01) of r=-0.272 with the oral health perception. Among the subgroups of the OHIP-14, quantitative linear relationship(p<0.01) was shown in functional limitation(r=0.822), physical pain(r=0.825), psychological discomfort(r=0.568), physical disability(r=0.895), psychological disability(r=0.652), social disability(r=0.804) and handicap(r=0.818). Conclusions: In order to improve the oral health perception and OHIP-14 in a geriatric hospital, it is necessary to develop continuously a variety of oral health education and systematic oral health promotion program.

농업용 콘크리트 구조물용 라텍스개질 보수용 모르타르의 수축 및 내구성능 평가 (Shrinkage and Durability Characteristics of Latex Modified Repair Mortar for Agricultural Concrete Structures)

  • 원종필;이재영;박찬기;박성기;김완영
    • 한국농공학회논문집
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    • 제49권5호
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    • pp.23-30
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    • 2007
  • This research was to evaluate the shrinkage and durability performance of latex modified repair mortar and to improve the service lift of the agricultural concrete structures. The shrinkage characteristics of the repair material creates the delamination of repair materials and existing concrete. It may reduce the service life of structures. Also the reduction of durability performance of the repair materials induces the destruction of the repaired concrete structures at early stage. In this research, plastic and drying shrinkage, thermal expansion coefficient for shrinkage properties, durability performance, permeability, repeated freezing and thawing, and resistance of chemical solution test were performed. Test results showed that the latex modified repair mortar indicated the shrinkage amount which the delamination does not happen, and the latex modified repair mortar appeared excellent long-term durability performance which can increase the service life.

부분적 단계충격 수명검사에 관한 직렬형 시스템의 최적 검사계획 (Optimal design of partially step-stress life testing for the series systems)

  • 박희창;이석훈
    • 응용통계연구
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    • 제8권2호
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    • pp.121-132
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    • 1995
  • 정상조건에서 수명이 상당히 긴 다수의 부품으로 구성된 직렬형 시스템의 수명검사를 현실적으로 수행하기 위해 부분적 단계충격 수명검사의 최적 검사계획에 관하여 고찰하였다. 시스템을 구성하고 있는 부품의 수명이 서로 독립인 지수분포를 따르는 것으로 가정하여 각 부품의 고장률과 가속인자의 최우추정량을 구하였다. 또한 각 부품의 고장률과 가속인자에 관한 최우추정량의 일반화 점근분산의 합과 각 부품의 가속인자에 관한 최우추정량의 점근분산의 합을 구하여 이를 최소가 되게 하는 최적변환시점의 결정방법을 제안하였다.

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질화규소 세라믹볼의 구름피로수명 (Rolling Fatigue Life of Silicon Nitride Ceramic Balls)

  • 최인혁;박창남;최헌진;이준근;신동우
    • Tribology and Lubricants
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    • 제15권2호
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    • pp.150-155
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    • 1999
  • The rolling fatigue lives (RFL) of five kinds of silicon nitride balls were investigated. Four kinds of Si$_3$N$_4$balls were fabricated using different raw materials, sintering aids and sintering conditions. Commercially available Si$_3$N$_4$ball was also studied for comparison. All the balls were finished up to the dimensional accuracy of Grade 10 defined in KS B 2001 (Steel Balls fer Ball Bearings) with a size of 9.525 mm. RFL tests were then conducted under the initial theoretical maximum contact stress 6.38 GPa and the spindle speed 10,000 rpm. Gear oil was provided by oiled race as lubricant. The results of RFL test indicated the prerequisitic conditions for the long rolling life of Si$_3$N$_4$ball : (1) the high density, (2) microstructures consisted of small uniformly distributed grains, (3) little glassy phase in grainboundary, and (4) little crystalline phase and secondary phase that induces residual thermal stress due to the differences of thermal expansion coefficient with Si$_3$N$_4$phase.

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

  • 이은경;정유인;김상식
    • 한국재료학회지
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    • 제25권10호
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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.