• Journal of Mechanical Science and Technology
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• v.20 no.4
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• pp.494-504
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• 2006

This research proposes a reliability-based topology optimization (RBTO) using the finite element method. RBTO is a topology optimization based on probabilistic (or reliability) constraints. Young's modulus, thickness, and loading are considered as the uncertain variables and RBTO is applied to static and eigenvalue problems. The RBTO problems are formulated and a sensitivity analysis is performed. In order to compute probability constraints, two methods-RIA and PMA-are used. Several examples show the effectiveness of the proposed method by comparing the classical safety factor method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.345-356
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• 2016

The purpose of this study was to develop a scale to evaluate the safety competency of perioperative nurses and to examine its validity and reliability. The research process included the development of preliminary items through literature reviews and the construct validity examination of the conceptual framework for the preliminary scale. The content validity of the identified items was evaluated by experts, resulting in 30 preliminary items. The participants involved in testing the validity and reliability of the preliminary scale were 377 perioperative nurses. The data were analyzed using exploratory factor analysis, parallel analysis, confirmatory factor analysis, and internal consistency. To verify the construction factor of the preliminary scale, exploratory factor analysis and parallel analysis were performed, resulting in 3 factors and 27 items. The internal structure of the scale was schematized using confirmatory factor analysis and the goodness of fit of the final research model was very appropriate, as shown by the values of TLI=.90, CFI=.91, RMSEA=.07, and SRMR=.07. The final scale consisted of 27 items and 3 factors including knowledge (6 items), skill (13 items), and attitude (8 items). Cronbach' ${\alpha}$ for the final scale was .94, showing good internal consistency. This safety competency scale can be used for assessing the competency of perioperative nurses regarding patient safety, for developing patient safety studies and for the career development of perioperative nurses.

• Nuclear Engineering and Technology
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• v.29 no.6
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• pp.433-443
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• 1997

In this work, an analytic approach to the dependability of software in the operational phase is suggested with special attention to the hardware fault effects on the software behavior : The hardware faults considered are memory faults and the dependability measure in question is the reliability. The model is based on the simple reliability theory and the graph theory which represents the software with graph composed of nodes and arcs. Through proper transformation, the graph can be reduced to a simple two-node graph and the software reliability is derived from this graph. Using this model, we predict the reliability of an application software in the digital system (ILS) in the nuclear power plant and show the sensitivity of the software reliability to the major physical parameters which affect the software failure in the normal operation phase. We also found that the effects of the hardware faults on the software failure should be considered for predicting the software dependability accurately in operation phase, especially for the software which is executed frequently. This modeling method is particularly attractive for the medium size programs such as the microprocessor-based nuclear safety logic program.

• Proceedings of the Safety Management and Science Conference
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• 2005.05a
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• pp.267-271
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• 2005

도시철도시스템은 차량, 전력, 신호, 선로구축물 등이 유기적으로 결합된 복합시스템으로 고장 또는 사고가 발생하면 원인규명이 어렵고 사고에 따른 영향이 매우 크기 때문에 시스템의 신뢰성과 안전성은 매우 중요하다. 본 논문에서는 철도에서 적용되고 있는 신뢰성관련 국제 규격을 분석하여 국내에서 개발하고 있는 무인운전 도시철도시스템에 이러한 규격들의 내용들을 충족하는 관리체계를 제시하고자 한다. 즉 기존에 적용하고 있는 신뢰성 관리체계인 IEC 60300, IEC 62278, MIL-STD-785B 등의 특성과 장점을 비교분석하여 도시철도시스템에 구체적으로 적용할 수 있는 신뢰성관리체계를 제시하고자 한다.

• Computational Structural Engineering
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• v.5 no.4
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• pp.113-124
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• 1992

This study proposes a Load Factors-based Analysis Model of Optimum Reliability for the High way bridge, which is most common type of structural design, and also proposes the theoretical bases of optimum nominal safety factors as well as optimum load and resistance factors based on the expected total cost minimization. Major 2nd moment reliability analysis and design theories including both MFOSM(Mean First Order 2nd Moment) Methods and AFOSM(Advanced First Order 2nd Moment) Methods are summarized and compared, and it has been found that Lind-Hasofer's approximate and an approximate Log-normal type reliability for mula are well suited for the proposed optimum reliability study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.6
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• pp.132-140
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• 2019

In this study, a specimen composed of columns, walls, beams, and slabs was fabricated to investigate the estimated reliability using nondestructive test method for the location of structural members of reinforced concrete single layer structures. And for accurate analysis in the comparison process with the existing estimation formula, we try to analyze the reliability through statistical approach by using error rate comparison and Confidence interval estimation. As a result, The average error rate of the core test was 18.8% compared with the result of estimating the compressive strength using the ultrasonic pulse velocity method. The average error rate of the core test results compared with the result of estimating the compressive strength using the rebound hardness method was 20.1%, confirming the field applicability. it is judged that the reliability of the compressive strength estimation can be derived from the wall member to make a quick and efficient structure safety diagnosis using the ultrasonic pulse velocity method. In addition, it is judged that the reliability of the compressive strength estimation can be derived from the beam member to make a quick and efficient structure safety diagnosis using the rebound hardness method.

• Journal of the Korean Society of Safety
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• v.11 no.1
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• pp.16-26
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• 1996

In a series of original papers, [1-17] efficient methods and algorithms have been presented, for the exact solution of many reliability problems represented by binary networks. A starting point of these methods was the concept of domination, firstly introduced in ,elation with reliability problems in [2]. It's application to directed networks resulted in the development of a topological formula for the classical problem of the two terminal reliability. This result was extended later to the all-terminal and the k-terminal reliability problems. All papers mentioned above use a path oriented representation for the network topology. In practical applications, however, it is common and often advantageous to work with cut sets. This article considers the Domination theory for reliability problem of a network. Some topological formula are derived and the power and the application of this formula are shown through the alternative proof of topological formula of A. Satyanarayana [2].

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.602-607
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• 1995

This article presents safety review experience of microprocessor-based Interposing Logic System(ILS) of Engineering Safety Feature Actuation System(ESFAS). The ILS is the first application of computerized logic design to safety system in Korean nuclear power plants without verification of the system reliability by proven technology concept. As a result of evaluation for the ILS, Korea Institute of Nuclear Safety(KINS) concluded that the microprocessor-based ILS is not acceptable in some features detailed enough to defend against software common mode failures(CMF). Therefore, we required licensee to install hardwired interlock signal configuration and a Hardwired Backup Panel to control safety-related equipment. We believe that the microprocessor-based ILS with the hardwired backup panel and inter-connection of interlock signal by hardwired configuration will improve the plant safety.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.77-82
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• 2010

This study evaluated the characteristics and reliability of an auger crane with a built-in hydraulic extender. The field test of the hydraulic extender was performed with the hydraulic lines filled with hydraulic fluid and free of air. The pressure generated during the test was measured with a digital pressure gauge. The crane was considered to have undergone one cycle of the excavation process after it had performed excavation under three conditions at the same location. This process was performed three times in total. From the results of the excavation using the hydraulic extender, it was found that the maximum pressure and torque measured were 19.9 [MPa] and 895.4 [$kgf{\cdot}m$], respectively. The rotation force of the auger crane generated at this time signifies a horizontal force. If the excavation diameter of the auger crane is increased, the rotation speed is reduced causing the circumferential speed to also be reduced. The torsional shear stress of the extendable auger crane was calculated to be approximately 23.5 [MPa]. However, the rotation shaft material used for this system was carbon steel for machine structural use (SM45C). Since the minimum torsional yield stress is greater than 150 [MPa] according to KS D 3752, it means the equipment has secured a safety factor greater than 6. Therefore, it was found that when performing work using the extendable auger crane, it exhibited no problems with the safety and reliability of its shaft.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.991-994
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• 2000

Recently, reliability engineering is regarded as the major field for aerospace and electronics, semiconductor related industry to improve safety and life cycle. And advanced manufacturing systems with high speed and intelligent have been developed for the betterment of machining ability In this case, reliability prediction has also important roll from design procedure to manufacturing and assembly process. Accordingly in this study, reliability evaluation system has been developed for prevention trouble. quality and life cycle improvement extremely for advanced mother machinary.