• Journal of Korean Society of Steel Construction
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• v.15 no.2
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• pp.187-196
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• 2003

Today, the Working Stress Rating (WSR) is being widely used for the capacity-rating and the safety assessment of railroad steel bridges. Since it cannot incorporate the uncertainties, several studies have been carried out in order to get over the incompleteness of the conventional capacity-rating and safety assessment. A system reliability-based equivalent capacity-rating method, which can evaluate the capacity of existing bridges, has been recently proposed. For more efficient reliability analysis, probabilistic parameters of the random variables in the limit-state models should be reasonably evaluated. Especially, uncertainties for live load effects must be realistically included. In this study, an improved limit-state model was used for the system reliability-based equivalent strength method. This model can incorporate the probabilistic parameters obtained from ambient measurement data. To demonstrate the applicability of the improved system reliability-based equivalent capacity rating method, this was applied to the existing steel plate girder bridge for comparison with the conventional capacity-rating and safety assessment.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.1
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• pp.7-14
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• 2002

In power system study, relibility assessment has been an important topic during past several decards because sudden power interruption can bring about enormous economic loss. although the size of a substation is smaller than that of generation system or transmission system, switching actions after fault(s) make reliability assessment of substation rather complex situations such as switching actions easily and permit various probability distributions in describing substation elements. Despite this ability of Monte Carlo simulation, one-parameter exponential distribution is still popular in this reliability assessment. This paper examines the characteristics of several two-parameter probability distributions, and offers new parameter decision rule based on average and variance of the target to be modelled. In case study, this paper shows the profits by using Weibull distribution which is one of two-parameter probabilistic distributions instead of exponential one.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.233-240
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• 2000

Nuclear power plant structures may be exposed to aggressive environmental effects than may cause their strength and stiffness to decrease over their service lives, Although the physics of these damage mechanisms are reasonably well understood and quantitative evaluation of their effects on time-dependent structural behavior is possible in some instances such evaluations are generally very difficult and remain novel. The assessment of existing RC containment in nuclear power plants for continued service must provide quantitative evidence that they are able to withstand future extreme loads during a service period with an acceptable level of reliability. Rational methodologies to perform the reliability assessment can be developed from mechanistic models of structural deterioration using time-dependent structural reliability analysis to take earthquake loading uncertainties into account. The final goal of this study is to develop the reliability analysis of RC containment structures. The cause of the degrading is first clarified and the reliability assessment has been conducted. By introducing stochastic analysis based on random vibration theory the reliability analysis which can determine the failure probabilities has been established.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.8
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• pp.4241-4254
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• 2019

The efficiency and accuracy of handwriting measurement could be improved by adopting digital image processing. This study developed a computer-based Korean Handwriting Assessment tool. Second graders participated in this study by performing writing tasks of consonants, vowels, words, and sentences. We extracted boundary parameters for each letter using digital image processing and calculated the variables of size, size coefficient of variation (CV), misalignment, inter-letter space, inter-word space, and ratio of inter-letter space to inter-word space. Children were also administered traditional handwriting and visuomotor tests. Digital variables from image processing were correlated with these previous tests. Using these correlations, we established a three-point scoring system that computed test scores for each variable. We analyzed inter-rater reliability between the computer rater and human rater and test-retest reliability between the first and second performances. The validity was examined by analyzing the relationship between the Korean Handwriting Assessment and previous handwriting and visuomotor tests. We suggested the Korean Handwriting Assessment to measure size, size consistency, misalignment, inter-letter space, inter-word space, and space ratio using digital image processing. This Korean Handwriting Assessment tool proved to have reliability and validity. It is expected to be useful for assessing children's handwriting.

• Journal of Korean Academy of Nursing Administration
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• v.4 no.2
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• pp.419-437
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• 1998

Nurses use a nursing process. that is a scientific approach method. in order to understand the clients' condition and to solve their problems. Professional nurses have accepted the nursing process as a standard framework for nursing activities, and the first step of the nursing process is nursing assessment. The purpose of this study was to develop a nursing assessment tool for emergency patients. Assessment is a first step in the nursing process, and scientific assessment helps to better understand the patients. Thus the development of an assessment tool for emergency patients will improve of nursing quality and advance to efficacy of emergency room(ER) management. The study involved the development of a conceptual framework, preliminary tool, content validity verification process. and reliability verification process. The conceptual framework was developed through a review of the literature. and preliminary tool was developed from the conceptual framework that based on care flow sheet' developed James A. Haley. The preliminary tool was evaluated for validity and reliability by seven experts, one ER nurse manager, two ER head nurses, two emergency medicine doctors. and two ER charge nurses and by ten nurses with one to five year careers in ER nursing. The results of this study was as follows 1. The conceptual framework which was developed was composed of three parts. They were triage criteria, first assessment and secondary assessment. 2. The preliminary tool which was developed had 31 items based on the conceptual framework. 3. To test expert validity a 4-point scale was used. items which had gained 3-4 points from six persons of the seven experts were selected. All 31 items from the preliminary tool were selected. 4. The reliability test was done by ten nurses educated in the use of the assessment tool. Two pairs of nurses simultaneously assessed the same patients. A total agreement percentile was calculated and result was 87.3% agreement. 5. After the validity and reliability testing. the final emergency patient nursing assessment tool was finalized with 31 items. and a check-list for the responses. This study concludes that the tool which was developed is both valid and reliable will advance quality care for emergency patients. This emergency nursing assessment tool was also found to be an adequate tool for assessment of emergency patients.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.853-858
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• 2004

In order to develop a high speed train, various conditions have been considered. Fatigue strength assessment by the fluctuation of pressure is an important one. When high speed train passing though tunnels, the pressure wave is generated in tunnels and pressure variation by the wave is acting on carbody structure with dynamic load repeatedly. In this study, formulation for reliability based fatigue assessment method has been performed when the high speed train passes through tunnels. The formulation was based on structural reliability index method and followed the proposed ISO method. The result by this study would be a good guidance to calculate the fatigue life and reliability index of body structure.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.254-259
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• 2007

PM(Preventive Maintenance) can avail the generating unit to reduce cost and gain more profit in a competitive supply-side power market. So, it is necessary to perform reliability analysis on the power systems in which reliability is essential. Thus, to schedule optimal PM planning based on reliability that is defined RCM(Reliability-Centered Maintenance), FMECA(Failure Mode Effects and Criticality Analysis) assessment is very important. Therefore, in this paper, the procedure of FMECA assessment for optimal RCM is proposed by probabilistic approach using real historical failure data of combustion-turbine generators in Korean power systems. The stochastic FMECA is performed based on the effects of probable failure modes of combustion-turbine generating unit.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3602-3620
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• 2016

Dynamic topology is one of the main influence factors on network performability. However, it was always ignored by the traditional network performability assessment methods when analyzing large-scale mobile ad hoc networks (MANETs) because of the state explosion problem. In this paper, we address this problem from the perspective of complex network. A two-layer hierarchical modeling approach is proposed for MANETs performability assessment, which can take both the dynamic topology and multi-state nodes into consideration. The lower level is described by Markov reward chains (MRC) to capture the multiple states of the nodes. The upper level is modeled as a small-world network to capture the characteristic path length based on different mobility and propagation models. The hierarchical model can promote the MRC of nodes into a state matrix of the whole network, which can avoid the state explosion in large-scale networks assessment from the perspective of complex network. Through the contrast experiments with OPNET simulation based on specific cases, the method proposed in this paper shows satisfactory performance on accuracy and efficiency.

• Nuclear Engineering and Technology
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• v.49 no.2
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• pp.360-372
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• 2017

Many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended because of deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Considering an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive Reactor Cavity Cooling System following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. Although this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability of the Reactor Cavity Cooling System (and the reactor system in general) for the postulated transient event.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.10a
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• pp.71-78
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• 1994

The main objectives of the study may be stated as follows : \circled1 the acquisition of fundamental updated data for the assessment of aged wharf structures of pier type based on systematic static/dynamic load testing \circled2 the study of techniques and methods for field testing \circled3 realistic safety and load carrying capacity assessment based on practical reliability analysis. In this study field testing of real structure is performed and the results are compared with those of the 2D and 3D linear structural analysis. It may be seen that the practical reliability methods can be applied for the safety and capacity assessment of aged wharf structures of pier type.