• Structural Engineering and Mechanics
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• 제71권2호
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• pp.165-173
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• 2019

This paper investigates the probability of failure of reinforced concrete beams for limit state of collapse for flexure and shear. The influence of randomness of the variables on the failure probability is also examined. The Indian standard code for plain and reinforced concrete IS456:2000 is used for the design of beams. Probabilistic models are developed for flexure and shear according to IS456:2000. The loads considered acting on the beam are live load and dead load only. Random variables associated with the limit state equation such as grade of concrete, grade of steel, live load and dead load are identified. Probability of failure is evaluated based on the limit state equation using First Order Reliability Method (FORM). Importance of the random variables on the limit state equations are observed and the variables are accordingly reduced. The effect of the reduced parameters is checked on the probability of failure. The results show the role of each parameter on the design of beam. Thus, the Indian standard guidelines for plain and reinforced concrete IS456:2000 is investigated with the probabilistic and risk-based analysis and design for a simple beam. The results obtained are also compared with the literature and accordingly some suggestions are made.

• Childhood Kidney Diseases
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• 제1권1호
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• pp.17-23
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• 1997

목적 : IgA 신병증은 다양한 임상 소견을 보일 수 있으며 초기에는 대부분 예후가 양호한 것으로 알려졌었으나 현재는 발병 20년후 20-30%가 말기 신부전증을 초래한다고 알려져 있다. IgA 신병증의 예후를 예측하기 위한 여러 조사에서 발병 초기의 심한 단백뇨, 고혈압, 조직 병리학 상의 심한 변화 등이 있을 경우 예후가 나쁘다고 하였다. 1996년 Yagame등은 IgA 신병증에서 새로운 조직 병리학적 분류를 하였고 WHO 분류 방법이 사구체 병변을 중심으로 한데 비해 세뇨관과 간질의 변화까지 포함하고 있어 이들의 분류 방법이 더 우수하며 추적관찰 결과 만성 신부전의 예후 인자로써 유용하다고 발표하였다. IgA 신병증에서 임상 증세, 검사 소견, WHO 및 Yagame 등의 조직 병리학적 분류 등과 추적 관찰시 만성 신부전과의 상관 관계를 알아보고자 하였다. 방법 : 1984년 1월부터 1996년 2월까지 소아과에 입원하여 신생검상 메산지움에 IgA가 현저히 침착되어 있어 IgA 신병증으로 진단된 환아 79명을 대상으로 평균 27개월의 추적관찰시 신 기능이 정상인군(73례)과 만성 신부전으로 진행한 군(6례)을 서로 비교하여 IgA 신병증에서의 예후 예측 인자에 대하여 알아보고자 하였다. 결과 : 1) 성별, 나이, 증상기간 등은 양군간 차이가 없었으나 내원시 고혈압이 있을 경우 만성 신부전으로의 진행이 많았다. 2) 내원시에 여러 임상 검사중 심한 단백뇨가 만성 신부전으로의 진행이 많았다. 3) WHO 및 Yagame 등의 조직 병리학적 분류 모두 소아 환자에서는 예후와의 관련을 찾을 수 없었다. 결론 : 이상의 결과로 보아 IgA 신병증 환아에서 내원시에 심한 단백뇨, 고혈압이 있을 경우 추적 관찰 결과 예후가 좋지 않았다. 그러나 본 연구의 경우 치료에 대한 평가가 이루어지지 않았고 대상 환아가 적었기에 향후 이를 포함하는 광범위한 연구가 진행되어야 할 것으로 사료된다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제11권4호
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• pp.387-398
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• 2011

$217Plus^{TM}$, a newly developed as a surrogate of the MIL-HDBK-217, may be widely applied for reliability predictions of electronic systems. In this study, we performed sensitivity study of the $217Plus^{TM}$ system model to various parameters. Specific attention was put to logistics model and its behavior has been examined in terms of non-component failure causes. We first briefly explained the $217Plus^{TM}$ methodology with system level failure rate evaluation. We then applied experimental designs with several failure causes as factors. We used an orthogonal array with three levels of each parameter. Our results indicate that cannot duplicate, induced, and wear-out causes have dominant effects on the system failures and design, parts, and system management have much less but a little strong effects. The results in this study not only figure out the behavior of the predicted failure rate as functions of failure causes but provide meaningful guidelines for practical applications.

• Asian Pacific Journal of Cancer Prevention
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• 제14권1호
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• pp.515-521
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• 2013

Purpose: To evaluate the efficacy and toxicity of induction chemotherapy followed by concurrent chemoradiotherapy (the treatment group) versus concurrent chemoradiotherapy with or without adjuvant chemotherapy (the control group) for locoregionally advanced nasopharyngeal carcinoma. Methods: The search strategy included Pubmed, Embase, the Cochrane Library, China National Knowledge Internet Web, Chinese Biomedical Database and Wanfang Database. We also searched reference lists of articles and the volumes of abstracts of scientific meetings. All randomized controlled trials were included for a meta-analysis performed with RevMan 5.1.0. The Grading of Recommendations Assessment, Development, and Evaluation system (GRADE) was used to rate the level of evidence. Results: Eleven studies were included. Risk ratios of 0.99 (95%CI 0.72-1.36), 0.37 (95%CI 0.20-0.69), 1.08 (95%CI 0.84-1.38), 0.98 (95%CI 0.75-1.27) were observed for 3 years overall survival, 3 years progression-free survival, 2 years loco-regional failure-free survival and 2 years distant metastasis failure-free survival. There were no treatment-related deaths in either group in the 11 studies. Risk ratios of 1.90 (95%CI 1.24-2.92), 2.67 (95%CI 0.64-11.1), 1.04 (95%CI 0.79-1.37), 0.98 (95%CI 0.27-3.52) were found for grade 3-4 leukopenia, grade 3-4 thrombocytopenia, grade 3-4 mucous membrane, and grade 3-4 hepatic hematologic and gastrointestinal toxicity, the most significant toxicities for patients. Conclusion: Compared with the control group, induction chemotherapy followed by concurrent chemoradiotherapy was well tolerated but could not significantly improve prognosis in terms of overall survival, loco-regional failure-free survival or distant metastasis failure-free survival.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2011년도 춘계학술발표대회 논문집
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• pp.257-264
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• 2011

In this study, we performed sensitivity study of the $217Plus^{TM}$ system model to various parameters. Specific attention was put to logistics model and its behavior has been examined in terms of non-component failure causes. We first briefly explained the $217Plus^{TM}$ methodology with system level failure rate evaluation. We then applied experimental designs with several failure causes as factors. We used an orthogonal array with three levels of each parameter. Our results indicate that cannot duplicate, induced, and wear-out causes have dominant effects on the system failures and design, parts, and system management have much less but a little strong effects. The results in this study not only figure out the behavior of the predicted failure rate as functions of failure causes but provide meaningful guidelines for practical applications.

• Smart Structures and Systems
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• 제26권2호
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• pp.147-156
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• 2020

This numerical study demonstrates the porosity conditions and the intensity of the interactions with the aggressive agents. It is established that the density as well as the elastic modulus are correlated to ultrasonic velocity The following investigation assessed the effects of cement grade and porosity on tensile strength, flexural and compressive of Ultra High Performance Concrete (UHPC) as a numerical model in PLAXIS 2d Software. Initially, the existing strength-porosity equations were investigated. Furthermore, comparisons of the proposed equations with the existing models suggested the high accuracy of the proposed equations in predicting, cement grade concrete strength. The outcome obtained showed a ductile failure when un-corroded reinforced concrete demonstrates several bending-induced cracks transfer to the steel reinforcement. Moreover, the outcome also showed a brittle failure when wider but fewer transverse cracks occurred under bending loads. Sustained loading as well as initial pre-cracked condition during the corrosion development have shown to have significant impact on the corrosion behavior of concrete properties. Moreover, greater porosity was generally associated with lower compressive, flexural, and tensile strength. Higher cement grade, on the other hand, resulted in lower reduction in concrete strength. This finding highlighted the critical role of cement strength grade in determining the mechanical properties of concrete.

• Structural Engineering and Mechanics
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• 제59권5호
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• pp.853-866
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• 2016

This paper examines a methodology for computing the probability of structural failure of reinforced concrete beams subjected to fire. The significant load variables considered are dead load, sustained live load and fire temperature. Resistance is expressed in terms of moment capacity with random variables taken as yield strength of steel, concrete class (or grade of concrete), beam width and depth. The flexural capacity is determined based on the design equations recommended in Indian standard IS456:2000. Simplified method named $500^{\circ}C$ isotherm method detailed in Eurocode 2 is incorporated for fire design. A transient thermal analysis is conducted using finite element software ANSYS$^{(R)}$ Release15. Reliability is evaluated from the initial state to 4h of fire exposure based on the first order reliability method (FORM). A procedure is coded in MATLAB for finding the reliability index. This procedure is validated with available literature. The effect of various parameters like effective cover, yield strength of steel, grade of concrete, distribution of reinforcement bars and aggregate type on reliability indices are studied. Parameters like effective cover of concrete, yield strength of steel has a significant effect on reliability of beams. Different failure modes like limit state of flexure and limit state of shear are checked.

• 한국안전학회지
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• 제15권2호
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• pp.103-110
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• 2000

This paper deal with the stability evaluation and suggestion of progressive failure slope in biotite granite area of Andong. Based on geological site investigation and field test, stability analysis of slope was performed in conjunction with limit equilibrium methods and stereographic projection. Additionally, initial design and construction procedure was critically evaluated. Series of the slope stability analysis reveals the detection of local wedge and plane failure under the current slope condition. It is additionally appeared that a certain synthetic behavior of circle and plane failure exists on the right spot where the overall failure's going in progress. In order to construct more stable slope based on the suitability for the real state of the slope circumstances, this study issues a solution to eliminate the primary factors which cause the instability, by means of the grade of weathering and RMR classification of rock mass.

• 한국안전학회지
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• 제24권4호
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• pp.53-58
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• 2009

The importance of process for repair and reinforcement of the bridge is increasing because of the lack of the fatigue load and stress, a lowering of the bridge load carrying capacity owing to impact and oscillation, deterioration on cultivation periods of the bridge, etc. Typically the experimenter values the bridge load carrying capacity by the real rating factor and response modification factor in bridge load rating through static load test and dynamic load test. But the error occurred in reliability of response modification factor in bridge load rating according to experience of experimenter. so tests of connecting probability theory and valuation of the bridge recently. The study is to compute the real load carrying capacity of the bridge and the rating factor and response modification factor on grade of the bridge, and calculate the probability of over-loaded truck load from Weigh In Motion(WIM) Data in FORTRAN programming applying to Monte-Carlo Simulation. At the result of this study, it is acquired that the new grade is computed for the probability of over-loaded truck load and surface inspection. The A grade is over 1.95, B grade is $1.55{\sim}1.94$, C grade is $1.26{\sim}1.54$, D grade is $1.14{\sim}1.25$, E grade is under 1.13 of rating factor, respectively.

• 한국초등과학교육학회지:초등과학교육
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• 제36권4호
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• pp.439-446
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• 2017

The purpose of this study was to compare Grit, failure tolerance and psychological well-being between elementary science gifted and general students. The subjects of this study were 48 science gifted students and 70 general students in the 5th and 6th grade of elementary school in Gyeonggi province. The results of this study were as follows: First, Grit, failure tolerance and psychological well-being of science gifted students were higher than those of the general students, there was a statistically significant difference. Second, science gifted students showed higher correlation between grit and failure tolerance, grit and psychological well-being than general students. Grit of science gifted students had a positive correlation with all sub-factors of academic failure tolerance and psychological well-being. In general students, there was a positive correlation with all sub-factors of Grit, academic failure tolerance, and psychological well-being except for the emotion sub-factor of academic failure tolerance. Thirdly, as a result of the regression analysis on the elements of failure tolerance affecting the Grit, science gifted students showed emotional factor but general students had behavioral factors. Also, as a sub-factor of psychological well-being on Grit, both science gifted and general students showed autonomy.