• 한국멀티미디어학회논문지
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• 제20권7호
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• pp.1046-1053
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• 2017

We propose a design method of high accuracy power measuring device and the method of securing the reliability of the measured data. As a design method for the development of the high accuracy power measuring device, the circuit was made by reflecting the high accuracy power measuring ICs and the CT (Current Transformer). To ensure the reliability of the power meter, we requested to the watt-hour meter certified testing organization to measure the error rate, and the error rate of active power based on the "Wattmeter Technical Standard(Revision notify 2014-283)" was measure, and the error rate was confirmed to be less than 0.1%.

• Structural Engineering and Mechanics
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• 제62권2호
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• pp.125-138
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• 2017

Reliability-based design optimization (RBDO) is a powerful tool for design optimization when considering probabilistic characteristics of design variables. However, it is often computationally intensive because of the coupling of reliability analysis and cost minimization. In this study, the concept of reliability mapping function is defined based on the relationship between the reliability index obtained by using the mean value first order reliability method and the failure probability obtained by using an improved response surface method. Double-loop involved in the classical RBDO can be converted into single-loop by using the reliability mapping function. Since the computational effort of the mean value first order reliability method is minimal, RBDO by using reliability mapping functions should be highly efficient. Engineering examples are given to demonstrate the efficiency and accuracy of the proposed method. Numerical results indicated that the proposed method has the similar accuracy as Monte Carlo simulation, and it can obviously reduce the computational effort.

• 대한안전경영과학회지
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• 제22권2호
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• pp.31-38
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• 2020

The study evaluated the accuracy and intra-rater reliability for OWAS (Ovako Working posture Analysing System), RULA (Rapid Upper Limb Assessment), REBA (Rapid Entire Body Assessment) to improve their evaluation accuracy and reliability. Participants (n = 163) with undergraduate degree were recruited in this study and trained for 6 hours about the ergonomic assessment methods. Ergonomic assessments were conducted using OWAS, RULA, and REBA for a representative work with dynamic posture found in manufacturing industries. The study compared action categories (overall level) and detailed evaluation scores for individual body part. Action categories of the participants significantly differed from the golden reference defined by ergonomic experts. The participants underrated or omitted scores for truck (37.4% of the participants) and legs (52.8%) in OWAS. Similarly, the participants underrated or omitted additional scores for all body parts except the hand and wrist in RULA (53.5%) and REBA (54.8%). On the other hand, the participants overrated scores for the hand and wrist in RULA (55.2%) and REBA (39.9%). The results found in this study can help of selecting focus points and parts during assessment and education to improve accuracy and reliability of the ergonomic assessment methods.

• 한국방재학회 논문집
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• 제8권3호
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• pp.77-86
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• 2008

현재 사용되고 있는 여러 가지 얕은기초 침하량 예측식에 대한 신뢰성 평가를 위해 얕은기초에 대한 각종 재하시험 데이터, 기초의 형상과 위치 및 지반 원위치시험 관련사항을 조사하여 데이터베이스(D/B)로 구축하였으며 이를 바탕으로 통계분석을 실시할 수 있는 해석프로그램을 제작하여 기존 침하량 산정 공식의 정확도(accuracy)와 신뢰수준(reliability), 특히, 기존 침하량 공식의 침하비(s/B) 대비 안정성을 평가하여 기 사용 5개식에 대한 평가결과를 제시하였다. 현재수준의 분석결과는 D/B의 양과 질에 좌우되므로 양질의 데이터를 추가로 확보하고 5가지 이외의 방법까지 분석하면 신뢰성과 정확성을 파악하면서 설계에 적용할 수 있을 것으로 판단된다.

• Structural Engineering and Mechanics
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• 제3권2호
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• pp.135-144
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• 1995

Since structural systems may fail in any one of several failure modes, computation of system reliability is always difficult. A method using numerical quadrature for computing structural system reliability with either one or more than one failure mode is presented in this paper. Statistically correlated safety margin equations are transformed into a group of uncorrelated variables and the joint density function of these uncorrelated variables can be generated by using the Maximum Entropy Method. Structural system reliability is then obtained by integrating the joint density function with the transformed safety domain enclosed within a set of linear equations. The Gaussian numerical integration method is introduced in order to improve computational accuracy. This method can be used to evaluate structural system reliability for Gaussian or non-Gaussian variables with either linear or nonlinear safety boundaries. It is also valid for implicit safety margins such as computer programs. Both the theory and the examples show that this method is simple in concept and easy to implement.

• Structural Engineering and Mechanics
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• 제62권2호
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• pp.139-142
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• 2017

For the conventional computational methods for structural reliability analysis, the common limitations are long computational time, large number of iteration and low accuracy. Thus, a new novel method for structural reliability analysis has been proposed in this paper based on response surface method incorporated with an improved genetic algorithm. The genetic algorithm is first improved from the conventional genetic algorithm. Then, it is used to produce the response surface and the structural reliability is finally computed using the proposed method. The proposed method can be used to compute structural reliability easily whether the limit state function is explicit or implicit. It has been verified by two practical engineering cases that the algorithm is simple, robust, high accuracy and fast computation.

• 대한기계학회논문집A
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• 제35권10호
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• pp.1291-1298
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• 2011

본 논문은 탄약, 미사일, 우주발사체 등과 같은 일회성(one-shot) 시스템의 가부반응데이터를 이용하여 신뢰도를 추정하는 새로운 방법을 제안한다. 제안한 방법은 모수 추정법을 기반으로 한다. 제안한 방법은 가부반응 데이터의 시간에 따른 고장 비율 감소를 고려하였으며 모수 추정법의 문제점을 극복할 수 있다. 기존 문헌에 공개된 7 가지 추정방법들과 제안한 방법과의 정확성을 비교하여 제안한 방법을 검증하였다. 정확성 비교 시, 다양한 샘플 수 변화를 고려하여 신뢰도 추정결과에 대한 SSE를 이용하였다. 정확성 비교 결과, 제안한 방법은 다른 방법에 비해 정확성이 높은 신뢰도 추정결과를 제공하였다.

• KIEAE Journal
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• 제13권1호
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• pp.109-123
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• 2013

The study is to probe a technical alternative to enhance the reliability and accuracy of the results of various landscape simulations. This study to present technical criteria that are necessary in each stage of target site analysis, picture taking, and computer synthesis and, through these to present supplementary plans to enhance the reliability and accuracy of landscape simulations. In order to derive more practical and empirical results in terms of the reliability of the results of landscape simulations, examples that actually passed landscape review were selected. With regard to study process, an analysis was made first to analyze the landscape report data of designs that passed the review to analyze their characteristics, to be followed by an integrated analysis of problems that were revealed in various landscape simulations. Important factors that affect directly the work of landscape simulations such as the specification of camera lenses that were used in picture taking, distance, and angle. Design the work was carried out using Auto CAD, 3DS Max, and Photoshop program in the same way as in actual design. For verification of their accuracy and reliability, the results were entrusted to experts who have implemented similar jobs. To seduce differences from those too landscape simulations that conduct trial experiment of the virtual space that are to be created in the future with accurate numerical values.

• Structural Engineering and Mechanics
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• 제45권5호
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• pp.595-611
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• 2013

This paper aims to compare three collocation point methods associated with the odd order stochastic response surface method (SRSM) in a systematical and quantitative way. The SRSM with the Hermite polynomial chaos is briefly introduced first. Then, three collocation point methods, namely the point method, the root method and the without origin method underlying the odd order SRSMs are highlighted. Three examples are presented to demonstrate the accuracy and efficiency of the three methods. The results indicate that the condition that the Hermite polynomial information matrix evaluated at the collocation points has a full rank should be satisfied to yield reliability results with a sufficient accuracy. The point method and the without origin method are much more efficient than the root method, especially for the reliability problems involving a large number of random variables or requiring complex finite element analysis. The without origin method can also produce sufficiently accurate reliability results in comparison with the point and root methods. Therefore, the origin often used as a collocation point is not absolutely necessary. The odd order SRSMs with the point method and the without origin method are recommended for the reliability analysis due to their computational accuracy and efficiency. The order of SRSM has a significant influence on the results associated with the three collocation point methods. For normal random variables, the SRSM with an order equaling or exceeding the order of a performance function can produce reliability results with a sufficient accuracy. The order of SRSM should significantly exceed the order of the performance function involving strongly non-normal random variables.

• Earthquakes and Structures
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• 제14권4호
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• pp.361-377
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• 2018

In this paper, an alternative reliability-based methodology is developed and implemented on the safety evaluation of structures subjected to seismic loading. To effectively elaborate the approach, structures are represented by finite elements and seismic loading is applied in time domain. The accuracy of the proposed reliability-based methodology is verified using Monte Carlo Simulation. It is confirmed that the presented approach provides adequate accuracy in calculating structural reliability. The efficiency and robustness in problems related to performance-based seismic design are verified. A structure designed by experts satisfying all post-Northridge seismic design requirements is studied. Rigidities related to beam-to-column connections are incorporated. The structure is excited by three suites of ground motions representing three performance levels: immediate occupancy, life safety, and collapse prevention. Using this methodology, it is demonstrated that only hundreds of deterministic finite element analyses are required for extracting reliability information. Several advantages are documented with respect to Monte Carlo Simulation. To showcase an applicability extension of the proposed reliability-based methodology, structural risk is calculated using simulated ground motions generated via the broadband platform developed by the Southern California Earthquake Center. It is validated the accuracy of the broadband platform in terms of structural reliability. Based on the results documented in this paper, a very solid, sound, and precise reliability-based methodology is proved to be acceptable for safety evaluation of structures excited by seismic loading.