• 한국과학교육학회지
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• 제30권2호
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• pp.275-290
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• 2010

중학생의 과학탐구활동 수행평가 시 총체적 채점과 분석적 채점의 신뢰도를 비교 분석하였으며, 분석적 채점을 하는 경우에는 신뢰도 확보를 위하여 채점척도의 수준을 어느 정도로 분석적으로 해야 하는지를 조사하였다. 중학생들이 작성한 4개의 과학탐구과제에 대한 활동지를 두 명의 채점자가 총체적 채점 방식, 분석적 채점 방식, 분석적 채점 중 채점척도를 2, 3, 4~7수준으로 다르게 하여 채점하였다. 총체적 채점 방식은 과제 간 내적 일치도가 높게 나타났으며, 분석적 채점 방식은 채점자간 신뢰도가 높게 나타났다. 또한 채점척도 3수준의 경우는 4~7수준의 경우와 활동간 내적 일치도와 채점자간의 신뢰도가 유사하게 나타났으나, 능력추정치별 학생의 분포, 문항곤란도 및 문항특성곡선의 경우 채점척도 3수준의 경우가 적절한 것으로 나타났다. 이러한 연구 결과는 과학탐구활동 수행평가 시 총체적 채점 방식을 선택하는 경우는 과제 간 내적일치도를 높일 수 있으며 분석적 채점 방식에 비해 낮게 나타나는 채점자 간 일치도를 높이기 위한 채점자간 협의등 방안이 필요하다는 것을 시사한다. 또한 분석적 채점 방식을 선택하는 경우는 채점척도 3수준으로 충분히 신뢰도를 확보할 수 있다는 점을 시사한다.

• 국제초고층학회논문집
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• 제9권2호
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• pp.175-185
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• 2020

Currently, few studies have been conducted to comprehend the seismic reliability of post-tensioned (PT) CLT shear wall structures, due to the complexity of this kind of structural system as well as due to lack of a reliable structural model. In this paper, a set of 4-, 8-, 12-, and 16-storey benchmark PT CLT shear wall structures (PT-CLTstrs) were designed using the direct displacement-based design method, and their calibrated structural models were developed. The seismic reliability of each PT-CLTstr was assessed based on the fragility analysis and based on the response surface method (RSM), respectively. The fragility-based reliability index and the RSM-based reliability index were then compared, for each PT-CLTstr and for each seismic hazard level. Results show that the RSM-based reliabilities are slightly less than the fragility-based reliabilities. Overall, both the RSM and the fragility-based reliability method can be used as efficient approaches for assessing the seismic reliabilities of the PT-CLTstrs. For these studied mid- and high-rise benchmark PT-CLTstrs, following their fragility-based reliabilities, the 8-storey PT-CLTstr is subjected to the least seismic vulnerability; while, following their RSM-based reliabilities, the 4-storey PT-CLTstr is subjected to the least seismic vulnerability

• International Journal of Safety
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• 제10권2호
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• pp.10-15
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• 2011

The reconfigurable control systems based on feedback controls are utilized to compensate for damages of actuators in control systems. Such systems have multiple feedback controls and switch them in accordance with the degrees of the failures of the actuators. In order to be able to assess those systems, this paper develops a method to obtain reliabilities of reconfigurable dynamical systems which are interconnected in parallel / series configuration. By calculating reliabilities of interconnected dynamical systems, it is possible to assess many dynamical systems by comparing their reliabilities. Firstly, reliabilities of subsystems are obtained according to the definitions of the failures in terms of robust reliability for each subsystem. Then, the reliability of overall system is calculated from reliabilities of subsystems, using the methodology employed for probabilistic safety assessment. Failure rates of subsystems with feedbacks for reconfiguration change in certain time periods because of the switching of feedback controls. In order to deal with this, combinations of subsystems which compose overall system for each time period are derived by the methodology mentioned above and then integrated to calculate the reliability of overall system for a specific time. An illustrative example shows the validity and details of the proposed method.

• 대한통합의학회지
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• 제9권1호
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• pp.193-202
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• 2021

Purpose : The purpose of this study is to examine inter-and intra-rater reliabilities of myotonometric measurements of tone, elasticity and stiffness for the erector spinae muscles of the young and the elderly populations. Methods : A total of 102 (69 young adults from K university and 33 older adults from the D community center in Daejeon) were enrolled in this study. The two different raters measured each side of the erector spinae muscles at prone position. After each rater performed first measurement for a subject, 30 minutes of rest was given. The same rater then repeated the second myometric measurement on the subject. The collected data on the tone, elasticity, and stiffness of the erector spinae were analyzed using intraclass correlation coefficient (ICC) to determine inter- and intra- rater reliabilities. Results : The inter-and intra-rater reliabilities of the myotonometric measurement of the erector spinae for the total subjects were excellent (ICC > 0.9, p < 0.001). Within each of the elderly group and the young group, inter- and intra-rater reliabilities were also excellent (ICC > 0.8~0.9 / p < 0.001, ICC > 0.75~0.9 / p < 0.001, each). Conclusion : The measurement of muscle tone, elasticity, and stiffness for the erector spinae muscles using the myotonometer had excellent reliability. It was confirmed that a highly reliable myometric measurement on the erector spinae can be obtained regardless of whether it is from young or elderly people. This suggests that the myotonometer can be a useful tool to measure muscular properties of the erector spinae of the young and old as an evaluative instrument.

• 대한산업공학회지
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• 제20권3호
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• pp.3-14
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• 1994

In this study, two reliability computational algorithms which respectively utilize a factoring method are proposed for a system represented by reliability block diagram. First, vertex factoring algorithm is proposed. In this algorithm, a reliability block diagram is considered as a network graph with vertex reliabilities. Second algorithm is mainly concerned with conversion of a reliabilities block diagram into a network graph with edge reliabilities. In this algorithm, the independence of edges is preserved by eliminating replicated edges, and in computing the reliability of a converted network graph, existing edge factoring algorithm is applied. The efficiency of two algorithms are compared for example systems with respect to computing times. The results shows that the second algorithm is shown to be more efficient than the first algorithm.

• 한국지능시스템학회:학술대회논문집
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• 한국지능시스템학회 2008년도 춘계학술대회 학술발표회 논문집
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• pp.362-365
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• 2008

In the conventional fuzzy system reliability analysis, the reliabilities of the fuzzy systems and the components of fuzzy systems are represented by real values between zero and one, fuzzy numbers, vague sets, interval valued fuzzy sets, etc. This paper propose a method to represent and analyze the reliabilities of the fuzzy systems based on the internal valued vague sets defined in the universe of discourse [0, 1]. In the interval valued vague sets, the upper bounds and the lower bounds of the conventional vague sets are represented as the intervals, therefore it can allow the reliabilities of a fuzzy system to represent and analyze in a more flexible manner.

• The Journal of Korean Physical Therapy
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• 제27권3호
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• pp.154-158
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• 2015

Purpose: The purpose of this study was to propose a new reference point for measurement of the infrasternal angle and to investigate the intra- and inter-rater reliabilities of infrasternal angle measurement using photographs. Methods: Twenty-four healthy male college students participated as subjects in this study. Photographs were taken of subjects in two postures, one standing with the shoulders relaxed and one standing with the shoulders at $150^{\circ}$ abduction. All photographs were analyzed using Image J software. Raters used the photographs to measure the infrasternal angle between the xiphoid process, the medial margin of rib and navel on the right and left sides. The reliability of the infrasternal angle measurement was assessed by means of intraclass correlation coefficients [ICC (3,1)]. The level of statistical significance was set at p<0.05. Results: The intra- and inter-rater reliabilities of the infrasternal angle measurement for the right side at rest were excellent (ICC=0.866 and 0.813, respectively), as were those for the left side at rest (ICC=0.919 and 0.846, respectively). At $150^{\circ}$ shoulder abduction, the intra- and inter-rater reliabilities for measurement of the infrasternal angle on the right side were excellent (ICC=0.972 and 0.778, respectively), as were those for the left side (ICC=0.914 and 0.826, respectively). Conclusion: These findings suggest that this technique can be successfully used to measure the infrasternal angle, thus suggesting a new reference point for determining the length of the internal oblique and external oblique muscles in clinical situations.

• 한국지능시스템학회논문지
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• 제18권4호
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• pp.445-450
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• 2008

퍼지시스템의 신뢰도를 분석하기 위해서 기존의 연구에서는 퍼지시스템의 구성요소의 신뢰도를 0과 1사이의 실수, 퍼지숫자, 신용구간, 모호집합, 구간값 퍼지집합 등으로 표현하였다. 본 논문에서 우리는 전체집합 [0, 1]에서 정의되는 구간값 모호집합을 기반으로 퍼지시스템의 신뢰도를 표현하고 분석하는 방법을 제안한다. 구간값 모호집합에서는 기존 모호집합[12, 14]의 상한과 하한을 각각 구간으로 표현한다. 그러므로 퍼지시스템의 신뢰도를 더 유연한 방법으로 표현하고 분석하는 것을 가능하게 한다. 제안한 방법은 Kumar[14]가 언급한 복잡한 퍼지 사다리꼴숫자 연간보다는 퍼지 삼각숫자의 간단한 산술연산을 사용하기 때문에 제안된 방법의 실행속도는 기존의 방법보다 실행이 더 빠르다.

• 대한전기학회논문지:전력기술부문A
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• 제52권7호
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• pp.401-406
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• 2003

Electric power industries in several countries are currently undergoing major changes, mainly represented by the privatizations of the power plants and distribution systems. Reliable operations of the power plants directly contribute to the revenue increases of the generation companies in such competitive environments. Strategic optimizations should be performed between the levels of the reliabilities to be maintained and the various preventive maintenance costs, which require the accurate estimations of the power plant reliabilities. However, accurate estimations of the power plant reliabilities are often limited by the lack of accurate power plant failure data. A power plant is not supposed to be failed that often. And if it fails, its impact upon the power system stability is quite substantial in most cases, setting aside the significant revenue losses and lowered company images. Reliability assessment is also important for Independent System Operators(ISO) or Market Operators to properly assess the level of needed compensations for the installed capacity based on the availability of the generation plants. In this paper, we present a power plant reliability estimation technique that can be applied when the failure data is insufficient. Median rank and Weibull distribution are used to accommodate such insufficiency. The Median rank is utilized to derive the cumulative failure probability for each ordered failure. The Weibull distribution is used because of its flexibility of accommodating several different distribution types based on the shape parameter values. The proposed method is applied to small size failure data and its application potential is demonstrated.

• 한국소음진동공학회논문집
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• 제14권5호
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• pp.410-415
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• 2004

To ensure a safe operation of the prototype KGT-74 kW small gas turbine, vibrational reliabilities of the compressor 1st, 2nd, and 3rd stages and turbine blades have been estimated and reviewed. FE analyses have been carried out to obtain the natural vibration characteristics of the blades, and impact modal testings have been performed on every each one of the blades to measure their 1st natural frequencies. Then, the Campbell diagram analyses have been carried out to judge the safety of the blades from resonant failures up to 6k harmonics. Results show that the compressor 1st stage blade is exposed to a potential resonant failure with 3k harmonic around a rated speed of 30,000 rpm but that the other compressor 2nd and 3rd stages and turbine blades are safe from resonant failures. Finally, 27,900 rpm is selected as the safe operation limit for the KGT-74 ㎾ gas turbine relative to the blade vibrations.