• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.662-674
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• 2017

This paper describes the multidisciplinary design optimization (MDO) process of a tailless unmanned combat aerial vehicle (UCAV) using global variable fidelity aerodynamic analysis. The developed tailless UAV design framework combines multiple disciplines that are based on low-fidelity and empirical analysis methods. An automated high-fidelity aerodynamic analysis is efficiently integrated into the MDO framework. Global variable fidelity modeling algorithm manages the use of the high-fidelity analysis to enhance the overall accuracy of the MDO by providing the initial sampling of the design space with iterative refinement of the approximation model in the neighborhood of the optimum solution. A design formulation was established considering a specific aerodynamic, stability and control design features of a tailless aircraft configuration with a UCAV specific mission profile. Design optimization problems with low-fidelity and variable fidelity analyses were successfully solved. The objective function improvement is 14.5% and 15.9% with low and variable fidelity optimization respectively. Results also indicate that low-fidelity analysis overestimates the value of lift-to-drag ratio by 3-5%, while the variable fidelity results are equal to the high-fidelity analysis results by algorithm definition.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1825-1834
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• 2022

Performing high-fidelity computational fluid dynamics (HF-CFD) to predict the flow and heat transfer state of the coolant in the reactor core is expensive, especially in scenarios that require extensive parameter search, such as uncertainty analysis and design optimization. This work investigated the performance of utilizing a multi-fidelity reduced-order model (MF-ROM) in PWR rod bundles simulation. Firstly, basis vectors and basis vector coefficients of high-fidelity and low-fidelity CFD results are extracted separately by the proper orthogonal decomposition (POD) approach. Secondly, a surrogate model is trained to map the relationship between the extracted coefficients from different fidelity results. In the prediction stage, the coefficients of the low-fidelity data under the new operating conditions are extracted by using the obtained POD basis vectors. Then, the trained surrogate model uses the low-fidelity coefficients to regress the high-fidelity coefficients. The predicted high-fidelity data is reconstructed from the product of extracted basis vectors and the regression coefficients. The effectiveness of the MF-ROM is evaluated on a flow and heat transfer problem in PWR fuel rod bundles. Two data-driven algorithms, the Kriging and artificial neural network (ANN), are trained as surrogate models for the MF-ROM to reconstruct the complex flow and heat transfer field downstream of the mixing vanes. The results show good agreements between the data reconstructed with the trained MF-ROM and the high-fidelity CFD simulation result, while the former only requires to taken the computational burden of low-fidelity simulation. The results also show that the performance of the ANN model is slightly better than the Kriging model when using a high number of POD basis vectors for regression. Moreover, the result presented in this paper demonstrates the suitability of the proposed MF-ROM for high-fidelity fixed value initialization to accelerate complex simulation.

• 한국시뮬레이션학회논문지
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• 제22권4호
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• pp.67-82
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• 2013

본 논문은 공학급 국방 모델의 시뮬레이션 성능 향상을 위해 다중 충실도(Multi-fidelity) 모델링 시뮬레이션(M&S: Modeling and Simulation) 기법을 제안한다. 제안하는 기법은 다양한 충실도를 지닌 모델을 활용하여 고 충실도 모델의 시뮬레이션과 비교하여 유사한 수준의 시스템 분석 결과를 얻음과 동시에 시뮬레이션 성능 측면에서 이득을 가져오는 방안이다. 다중 충실도 원리를 적용하기 위해 본 논문은 충실도를 모델 동작과 실행 측면으로 세분화하고, 충실도 변환 지점을 FCP (Fidelity Change Point)로 정의한다. 이러한 원리를 바탕으로 본 논문은 다음의 세 가지 쟁점을 다룬다. 먼저, 모델 동작과 실행 측면의 충실도 변환을 위한 모델 구조와 제안하는 모델에 대한 수학적 형식론, 마지막으로 모델 실행을 위한 시뮬레이션 알고리즘을 제안한다. 사례 연구로 어뢰의 표적 추적 시나리오에 대한 기초 실험을 수행하였고, 실험 결과 제안하는 기법을 사용한 경우 기존의 시뮬레이션과 비교하여 최대 4.24배의 시뮬레이션 성능 향상을 보임을 확인하였다. 본 논문에서 제안하는 기법은 M&S 기반의 시스템 분석을 하는 다양한 분야에서 활용될 수 있음을 기대한다.

• 한국IT서비스학회지
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• 제5권2호
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• pp.59-78
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• 2006

This research is to suggest the factor which is effecting on the information system audit fidelity in the perspective of audit procurer, to develop the measure to evaluate it, to investigate the audit performance and project performance for comparison the audit fidelity between the audit teams. As the analysis results, we found that the audit service factors can be divided to the expert knowledge of auditor and the project attributes itself. It means these factors are the major measures for the audit fidelity. In this research, the hypothesis of this study model is verified throughout the factor and corelation analysis, and the structured equation model is applied. Analysis results show that all relations between the factors are significant statistically. The audit service factors has an effect on audit fidelity. Also the information system audit fidelity can be affect on the project performance, audit performance and customer satisfaction. So, in conclusion, we need to judge closely the audit service factors affecting the audit fidelity for the enhancement of the project performance, audit performance and customer satisfaction.

• 대한간호학회지
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• 제43권2호
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• pp.185-193
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• 2013

Purpose: Simulation-based learning has become a powerful method to improve the quality of care and help students meet the challenges of increasingly complex clinical practice settings. The purpose of this study was to identify the learning effects using high-fidelity SimMan and multi-mode simulation. Methods: Participants in this study were 38 students who were enrolled in an intensive course for a major in nursing at R college. Collected data were analyzed using Chi-square, t-test, and independent t-test with the SPSS 18.0 for Windows Program. Results: There were no statistically significant differences in learning effects between high-fidelity SimMan and multi-mode simulation group. However, skills in clinical performance in the high-fidelity SimMan group were higher than in the multi-mode group (p=.014), communication in clinical performance in multi-mode simulation group was higher than in the high-fidelity SimMan group (p<.001). Conclusion: Multi-mode simulation with a standardized patient is an effective learning method in many ways compared to a high-fidelity simulator. These results suggest that multi-mode simulation be offered to students in nursing colleges which cannot afford to purchase a high-fidelity simulator, or offered as an alternative.

• 대한물리치료과학회지
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• 제28권1호
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• pp.54-61
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• 2021

Background: The present study was performed to examine the factors required for active engagement of participants in exercise therapy by surveying the frequency of participation, fidelity of performance, and supporting materials and rewards provided to encourage participation in the study. Design: Cross-sectional study. Methods: The survey was conducted in a population of 103 participants in at least one exercise treatment study. A 12-item questionnaire was designed to determine the frequency of exercise participation and fidelity of participant performance. Results: The results were subjected to frequency analysis and Pearson's correlation analysis. The subjects were less likely to exercise with the therapist and less likely to exercise at home. In addition, the provision of supplementary materials, to be considered when exercising at home, was insufficient. A strong positive correlation was found between the frequency of exercise in the presence of a therapist and the fidelity of participant performance (r=0.812, p=0.001), whereas a weak negative correlation was found between the frequency of unperformed exercises and the fidelity of participant performance (r=-0.523, p=0.023). Conclusion: The results of the present study suggested that it is necessary to increase the number of times that exercises are performed with the therapist to motivate increased frequency of exercise participation and fidelity of participant performance. In addition, appropriate rewards and periodic management are required.

• 한국항공우주학회지
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• 제42권2호
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• pp.108-118
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• 2014

근사모델을 이용한 최적설계 문제에서는 설계변수의 수가 증가함에 따라 근사모델의 정확도를 확보하기 위한 계산 횟수가 급격히 증가한다. 이를 해결하기 위해 저정확도 모델을 바탕으로 고정확도 모델로 보정하는 Variable-Fidelity Modeling을 이용하였다. 본 논문에서 Variable-Fidelity Model로는 계층적 크리깅 모델을 이용하였으며, 다목적 유전자 알고리즘과 결합하여 최적화 프레임워크를 제안하였다. 이 방법의 유용성을 검증하기 위하여 천음속 영역에 대한 익형 최적 설계를 하였다. 설계변수로는 PARSEC의 파라메터를 이용하였으며, 서로 다른 격자수를 가지는 경우 그리고 서로 다른 정확도를 가지는 해석자를 이용한 경우에 관하여 해석을 수행하였다. 검증을 위해 단일 정확도 모델에 대한 최적화 결과와 비교하였다. 모든 경우에 관하여 파레토 라인이 유사하게 나오는 것을 확인 할 수 있었으며, 계산시간은 계층적 크리깅 모델을 이용한 Variable-Fidelity Model이 단일 정확도 모델에 비하여 훨씬 줄어들었다. 이를 바탕으로 본 논문의 방법이 단일 정확도를 가지는 모델에 대한 최적화 방법과 유사한 정확도를 가지며 더욱 효율적임을 확인 할 수 있다.

• 한국간호교육학회지
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• 제19권3호
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• pp.362-370
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• 2013

Purpose: The purpose of this study was to develop and evaluate effects of the integrative fidelity simulation curriculum. Methods: The integrative fidelity simulation curriculum was developed through meetings of experts based on nursing content. To test the application effect of simulation curriculum, a one group pre-post test design was applied. The simulation curriculum was applied with 149 nursing students who participated voluntarily. Results: In the application of satisfaction of the curriculum, learning interest in nursing and intrinsic motivation, nursing students had high scores in all evaluations. In addition, satisfaction of the curriculum had a significant positive correlation with learning interest in nursing and intrinsic motivation. Conclusion: The integrative fidelity simulation was an effective teaching tool for nursing students, and needs to develop more varied nursing simulation scenarios and curriculum.

• 한국학교수학회논문집
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• 제17권1호
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• pp.45-71
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• 2014

이차곡선에 대해 고교과정에서는 종합적인 개념습득이 이루어질 기회가 부족하고 대학과 정은 고등수학적 접근으로 진행되어 여전히 개념습득의 어려움을 갖는다는 점을 인식하고 예비교사들의 문제제기에 의한 수학적 사고확장을 돕고자 그래핑 계산기를 활용하여 수학적, 인지적, 교수적 충실도를 조사하였다. 인지적 충실도에서는 세 가지 수학적 속성의 문제제기가 이루어졌으며 이 때 수학적 충실도가 인지적 충실도와 순환적 연관성을 보였으며 교수적 충실도는 인지적 충실도를 더욱 활성화시키는 것으로 나타났다.

• 여성건강간호학회지
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• 제26권3호
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• pp.240-249
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• 2020

Purpose: This study was conducted to investigate the effects of an education program using a high-fidelity simulator of labor and delivery on nursing knowledge, critical thinking, and clinical performance among nursing students who had not yet experienced clinical practicum. Methods: The development of a 5-week maternity nursing education programs using high-fidelity simulators included modules containing case-oriented scenarios, knowledge, and skills required for maternity care. A randomized controlled study was conducted to verify the effects of the developed program. Data were collected from October 21 to December 9, 2019. The experimental group (n=36) participated in a 5-week high-fidelity simulation program on care for the woman in labor, whereas the control group (n=36) received standard education as lecture and practice with delivery model. The collected data were analyzed using descriptive statistics (frequency, percentage, mean, and standard deviation), the Chi-square test, Fisher exact test, and t-test. Results: For participants who received education using the high-fidelity simulation program, nursing knowledge (t=2.33, p=.011), critical thinking (t=3.73, p<.001), and clinical performance (t=2.53, p=.006) were significantly higher than in the control group. Conclusion: Even for students with no clinical experience, high-fidelity simulation-based nursing education was effective in improving nursing knowledge, critical thinking, and clinical performance among nursing students. Nurse educators will be able to use this high-fidelity simulator effectively, especially in situations where direct clinical practicum may not be feasible.