• Title/Summary/Keyword: reliability sensitivity

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Development of Nurse Presence Scale (Nurse Presence 도구개발)

  • 조계화;조영숙
    • Journal of Korean Academy of Nursing
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    • v.31 no.3
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    • pp.369-379
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    • 2001
  • Purpose: The purpose of this study was to develop the Nurse Presence Scale and to test the reliability and validity of the instrument. Method: The subjects verifying the scale's reliability and validity were adult patients being treated in three artificial kidney unit in Pusan and Taegu from August 1 to October 15, 2000. The data was analyzed by the SPSS/WIN 8.0 program. Result: A factor analysis and was conducted items that had a factor loading more than .40, and an eigen value more than 1.0 were seleclted. The factor analysis classified a total of seven factors statistically, but the seventh factor was excluded because community was less than 4%. Therefore, there were six factors, and its communality was 62%. The explanation of domain and factors based on the conceptual framework and item content are as follows: The first factor was 'interaction' in emotional areas, the second domain was 'empathy' in cognitive areas, the third was 'attention' in emotional areas, the fourth was 'openness' in emotional areas, the fifth was 'sensitivity' in behavioral areas, and the sixth was 'physical assist' in behavioral areas. Cronbach's α coefficient to test reliability of the scale was .9766 for a total 49 items. Conclusion: The Scale for Nurse Presence developed in the study was identified as a tool with a high degree of reliability and validity. Therefore, this scale can be effectively utilized for the evaluation of nurse presence in clinical settings.

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Reliability analysis of surface settlement during shield TBM tunneling (쉴드 TBM 터널 굴착시 지표침하에 관한 신뢰성해석)

  • Han, Myeong-Sik;Cho, Kuk-Hwan
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.3
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    • pp.305-318
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    • 2016
  • This study is to evaluate the uncertainty of the soil parameters associated with the Gap parameter during shield TBM tunnel excavation of ${\bigcirc}{\bigcirc}$ International Airport Terminal 2 connecting railway construction basic design. And This study is to evaluate the adequacy of the shield TBM design by performing a reliability analysis of the Surface settlement. In addition, By analyzing the reliability indices of the design constants and Sensitivity probability of failure to be used in designing an integer parameter Gap, and By evaluating the design constants of a great influence on the surface subsidence, it was to provide a basis for carrying out an optimum design.

Probabilistic failure analysis of underground flexible pipes

  • Tee, Kong Fah;Khan, Lutfor Rahman;Chen, Hua-Peng
    • Structural Engineering and Mechanics
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    • v.47 no.2
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    • pp.167-183
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    • 2013
  • Methods for estimating structural reliability using probability ideas are well established. When the residual ultimate strength of a buried pipeline is exceeded the limit, breakage becomes imminent and the overall reliability of the pipe distribution network is reduced. This paper is concerned with estimating structural failure of underground flexible pipes due to corrosion induced excessive deflection, buckling, wall thrust and bending stress subject to externally applied loading. With changes of pipe wall thickness due to corrosion, the moment of inertia and the cross-sectional area of pipe wall are directly changed with time. Consequently, the chance of survival or the reliability of the pipe material is decreased over time. One numerical example has been presented for a buried steel pipe to predict the probability of failure using Hasofer-Lind and Rackwitz-Fiessler algorithm and Monte Carlo simulation. Then the parametric study and sensitivity analysis have been conducted on the reliability of pipeline with different influencing factors, e.g. pipe thickness, diameter, backfill height etc.

Design Optimization of a Deep-sea Pressure Vessel by Reliability Analysis (신뢰성 해석을 이용한 심해용 내압용기의 설계 최적화)

  • JOUNG TAE-HWAN;NHO IN-SIK;LEE JAE-HWAN;HAN SEUNG-HO
    • Journal of Ocean Engineering and Technology
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    • v.19 no.2 s.63
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    • pp.40-46
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    • 2005
  • In order to consider the statistical properties of probability variables which are used in structural analysis, the conventional approach of using safety factors based on past experience, are usually used to estimate the safety of a structure. The real structures could only be analyzed with the error in estimation of loads, materials and dimensional characteristics. Errors should be considered systematically in the structural analysis. In this paper, we estimated the probability of failure of two pressure vessels, simultaneously, using computational analysis. One pressure vessel, theoretically, had no stiffener whereas the other had. This paper also discusses sensitivity values of random variables in the rounded parts of the pressure vessel which had ring-style stiffener in the center of the external area which had ring-style stiffener. Finally, we show that the reliability index, and the probability of failure, can be calculated to particular tolerance limits.

Probability of Failure of Armor Units on Rubble-mound Breakwater with Safety Factor (안전계수에 따른 경사제 피복재의 파괴확률)

  • 이철응;안성모
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.13 no.1
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    • pp.9-17
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    • 2001
  • A probability of failure of armor units on rubbJe-mound breakwater are evaluated by using the direct method for reliability analysis, which is represented as a function of safety factor that has been extensively used in practical design. The reliability function is fonnulated based on Hudson formula suggested for designing the stable size of armor units on rubble-mound breakwater. Several kinds of stability coefficient are applied separately to calculate the probability of failure with respect to the type of armor units, breaking/nonbreaking and the correlation coefficients between random variables. [n addition, the sensitivity analyses are carried out to investigate quantitatively into the effects of each random variable in the reliability function on the probability of failure.

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Downlink Parallel Transmit Power Control Algorithm during Soft handover for WCDMA System (WCDMA 소프트 핸드오버 시 하향 병렬 전송 전력 제어 알고리즘)

  • Han Young ok;Seo kyung Jin;Park Sung kwon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.4A
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    • pp.271-281
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    • 2005
  • This paper for establishing the reliability of the TPC command is introduced, where the soft symbol of the TPC command itself is directed used as a reliability indicator. In addition to the new reliability estimation, the concept of parallel use of TPC algorithms is presented. The results show that the soft symbol reliability estimation decrease the $P_{tx}$ levels with 0.3 dB, thus providing a useful capacity gain. The parallel use of 2 to 4 algorithms is also shown to decrease the sensitivity of the algorithms to the algorithm thresholds used, and thus increase the feasibility of the algorithms in a real world networks.

Development of the Korean Geriatric Loneliness Scale (KGLS) (한국 노인의 외로움 측정도구 개발)

  • Lee, Si Eun
    • Journal of Korean Academy of Nursing
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    • v.49 no.5
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    • pp.643-654
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    • 2019
  • Purpose: The purpose of this study was to develop and psychometrically test the Korean Geriatric Loneliness Scale (KGLS). Methods: The initial items were based on in-depth interviews with 10 older adults. Psychometric testing was then conducted with 322 community-dwelling older adults aged 65 or older. Content, construct, and criterion-related validity, classification in cutoff point, internal consistency reliability, and test-retest reliability were used for the analysis. Results: Exploratory factor analysis showed three factors, including 15 items explaining 91.6% of the total variance. The three distinct factors were loneliness associated with family relationships (34.3%), social loneliness (32.4%), and a lack of belonging (24.9%). As a result of confirmatory factor analysis, 14 items in the three-factor structure were validated. Receiver operating characteristic analysis demonstrated that the KGLS' cutoff point of 32 was associated with a sensitivity of 71.0%, specificity of 80.2%, and area under the curve of .83. Reliability, as verified by the test-retest intraclass correlation coefficient, was .89, and Cronbach's ${\alpha}$ was .90. Conclusion: As its validity and reliability have been verified through various methods, the KGLS can contribute to assessing loneliness in South Korean older adults.

Reliability Analysis of Ship′s Longitrdinal Strength for the Rational Ship Structural Design (선박구조설계 합리화를 위한 선체 종강도의 신뢰성 해석)

  • Oi-H. Kim;Byung-J. Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.32 no.1
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    • pp.25-36
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    • 1995
  • The application of the reliability analysis is investigated as a probabilistic approach to the assessment of ship's structural strength and to the establishment of design format for longitudinal strength. Reliability analyses are carried out for 34 ships of tankers and bulk carriers built in HHI for some failure modes such as tensile yielding, compressive buckling and ultimate strength of hull girder. The safety assessment of each ship, the calculation of sensitivity factors and the derivation of target reliability index are performed. As results. the difference of reliability indices among ships is great for all modes. To provide more uniform levels of safety the establishment of new strength criteria using partial safety factors is performed. The partial safety factors for the design format are obtained according to the AFOSM method and the reliability-conditioned(RC) method. Finally, a design format using partial safety factors has been proposed. We could find out that new strength criteria can produce consistent reliability indices which are close to the target value.

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Design Optimization and Reliability Analysis of Jacket Support Structure for 5-MW Offshore Wind Turbine (해상풍력발전기 자켓 지지구조물의 최적설계 및 신뢰성해석)

  • Lee, Ji-Hyun;Kim, Soo-Young;Kim, Myung-Hyun;Shin, Sung-Chul;Lee, Yeon-Seung
    • Journal of Ocean Engineering and Technology
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    • v.28 no.3
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    • pp.218-226
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    • 2014
  • Since the support structure of an offshore wind turbine has to withstand severe environmental loads such as wind, wave, and seismic loads during its entire service life, the need for a robust and reliable design increases, along with the need for a cost effective design. In addition, a robust and reliable support structure contributes to the high availability of a wind turbine and low maintenance costs. From this point of view, this paper presents a design process that includes design optimization and reliability analysis. First, the jacket structure of the NREL 5-MW offshore wind turbine is optimized to minimize the weight and stresses, while satisfying the design requirements. Second, the reliability of the optimum design is evaluated and compared with that of the initial design. Although the present study results in a new optimum shape for a jacket support structure with reduced weight and increased reliability, the authors suggest that the optimum design has to be accompanied by a reliability analysis during the design process, as well as reliability based design optimization if needed.

Evaluating the Reliability of Short-Form Berg Balance Scales and Short-Form Postural Assessment Scales in Chronic Stroke Survivors

  • Seung-Heon An;Dae-Sung Park
    • Physical Therapy Rehabilitation Science
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    • v.13 no.2
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    • pp.143-151
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    • 2024
  • Objective: This study aims to assess the test-retest reproducibility of the Short Form Berg Balance Scale (SF-BBS) and the Short Form Postural Assessment Scale for Stroke (SF-PASS) among chronic stroke survivors, focusing on their reliability for consistent measurements over time. Design: A cross-sectional study design Methods: Thirty chronic stroke survivors participated in this study, undergoing evaluations with SF-BBS and SF-PASS scales at two different points, separated by a seven-day interval. The analysis focused on test-retest reliability, employing statistical measures such as the Intra-Class Coefficient (ICC2,1), Standard Error of Measurement (SEM), Minimal Detectable Change (MDC), and MDC%, the Bland-Altman plot to assess the limits of agreement and the extent of random measurement error. Results: The study found notable test-retest reproducibility for both SF-BBS and SF-PASS, with ICC values demonstrating strong reliability (0.932 to 0.941, with a confidence interval of 0.889 to 0.973). SEM values for SF-BBS and SF-PASS were reported as 1.34 and 0.61, respectively, indicating low measurement error. MDC values of 3.71 for SF-BBS and 1.69 for SF-PASS suggest that the scales have an acceptable level of sensitivity to change, with reliability metrics falling below 20% of the maximum possible score. Conclusions: The findings suggest that both SF-BBS and SF-PASS exhibit high intra-class correlation coefficients, indicating strong test-retest reliability. The SEM and MDC values further support the scales' reproducibility and reliability as tools for evaluating mobility and dynamic balance in chronic stroke survivors. Therefore, these scales are recommended for clinical use in this population, providing reliable measures for assessing progress in rehabilitation.