• Structural Engineering and Mechanics
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• 제12권6호
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• pp.573-594
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• 2001

A two-level displacement-based design procedure is developed. To obtain the displacement demands, elastic spectra for occasional earthquakes and inelastic spectra for rare earthquakes are used. Minimum global stiffness and strength to be supplied to the structure are based on specified maximum permissible drift limits and on the condition that the structure responds within the elastic range for occasional earthquakes. The performance of the structure may be assessed by an inelastic push-over analysis to the required displacement and the evaluation of damage indices. The approach is applied to the design of a five-story reinforced concrete coupled wall structure located in the most hazardous seismic region of Argentina. The inelastic dynamic response of the structure subjected to real and artificially generated acceleration time histories is also analyzed. Finally, advantages and limitations of the proposed procedure from the conceptual point of view and practical application are discussed.

• Steel and Composite Structures
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• 제46권1호
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• pp.107-114
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• 2023

A new intelligent adaptive control scheme was proposed that combines observer disturbance-based adaptive control and fuzzy adaptive control for a composite structure with a mass-adjustable damper. The most important advantage is that the control structures do not need to know the uncertainty limits and the interference effect is eliminated. Three adjustable parameters in LMI are used to control the gain of the 2D fuzzy control. Binary performance indices with weighted matrices are constructed to separately evaluate validation and training performance using the revalidation learning function. Determining the appropriate weight matrix balances control and learning efficiency and prevents large gains in control. It is proved that the stability of the control system can be ensured by a linear matrix theory of equality based on Lyapunov's theory. Simulation results show that the multilevel simulation approach combines accuracy with high computational efficiency. The M-TMD system, by slightly reducing critical joint load amplitudes, can significantly improve the overall response of an uncontrolled structure.

• Steel and Composite Structures
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• 제32권2호
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• pp.189-198
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• 2019

This paper aims to study the mechanical performance of three-tower four-span suspension bridges with steel truss girders, including the static and dynamic characteristics of the bridge system, and more importantly, the influence of structural parameters including the side-main span ratio, sag-to-span ratio and the girder stiffness on key mechanical indices. For this purpose, the Oujiang River North Estuary Bridge which is a three-tower four-span suspension bridge with two main spans of 800m under construction in China is taken as an example in this study. This will be the first three-tower suspension bridge with steel truss girders in the world. The mechanical performance study and parametric analysis are conducted based on a validated three-dimensional spatial truss finite element model established for the Oujiang River North Estuary Bridge using MIDAS Civil. It is found that a relatively small side-main span ratio seems to be quite appropriate from the perspective of mechanical performance. And decreasing the sag-to-span ratio is an effective way to reduce the horizontal force subjected to the midtower and improve the antiskid safety of the main cable, while the vertical stiffness of the bridge will be reduced. However, the girder stiffness is shown to be of minimal significance on the mechanical performance. The findings from this paper can be used for design of three-tower suspension bridges with steel truss girders.

• 콘크리트학회논문집
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• 제26권6호
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• pp.771-778
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• 2014

본 연구에서는 하이브리드 강섬유로 보강된 초고성능 콘크리트(UHPC)의 휨거동 특성을 파악하고자 하였다. 부피비 1.5%의 하이브리드 강섬유를 혼입하여 철근비가 0.02 이하인 부재의 실험을 통해 주요 휨거동 특성을 파악하였다. 본 연구결과는 추후 UHPC의 휨강도 산정 모델링에 실제적인 기초실험자료로 활용될 수 있을 것으로 사료된다. 하이브리드 강섬유 보강 UHPC는 균열제어에 효과적이며, 연성지수는 9.2~15.2 범위에 분포하고 있어 우수한 연성거동 특성을 나타낸다. 또한, 순수 휨 구간 내에 스터럽을 배근한 부재의 휨강도는 스터럽을 배근하지 않은 부재의 휨강도와 유사하며, 이 실험연구의 150 mm 간격 정도의 스터럽 배근은 강섬유 배열 및 휨강도에 영향을 미치지 않는다고 판단된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권1호
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• pp.257-271
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• 2016

The Structural SIMilarity (SSIM) index is one of the most widely-used methods for perceptual image quality assessment (IQA). It is based on the principle that the human visual system (HVS) is sensitive to the overall structure of an image. However, it has been reported that indices predicted by SSIM tend to be biased depending on the type of distortion, which increases the deviation from the main regression curve. Consequently, SSIM can result in serious performance degradation. In this study, we investigate the aforementioned phenomenon from a new perspective and review a constant that plays a big role within the SSIM metric but has been overlooked thus far. Through an experimental study on the influence of this constant in evaluating images with SSIM, we are able to propose a new solution that resolves this issue. In the proposed IQA method, we first design a system to classify different types of distortion, and then match an optimal constant to each type. In addition, we supplement the proposed method by adding color perception-based structural information. For a comprehensive assessment, we compare the proposed method with 15 existing IQA methods. The experimental results show that the proposed method is more consistent with the HVS than the other methods.

• 한국구조물진단유지관리공학회 논문집
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• 제13권1호통권53호
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• pp.169-178
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• 2009

링 형태의 강섬유 (Ring-type steel fibers: 이하 RSF)는 원형의 폐곡선 형태를 갖는 강섬유로서 선형 강섬유와는 다른 저항 메카니즘을 가지며 폐곡선으로 둘러싸인 평면에 대하여 동일한 방향성을 가지는 특성을 갖는다. 이 연구에서는 섬유의 단위투입량 $15kg/m^3$과 $30kg/m^3$의 RSF 및 선형 강섬유를 혼입한 콘크리트 패널의 휨인성을 실험, 비교하였다. 파단면에서의 RSF의 저항 형태를 규명하였으며 RSF를 혼입한 패널이 선형 강섬유를 혼입한 패널에 비하여 우수한 인성값을 나타냄이 관찰되었다. RSF에 대한 방향성을 제시하였으며 RSF를 혼입한 실험체의 경우, 보 실험체에 비하여 두께가 상대적으로 얇은 패널 실험체에서 RSF가 더 효율적으로 인성 증가에 기여함이 관찰되었다.

• 간호행정학회지
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• 제17권3호
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• pp.284-292
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• 2011

Purpose: The purpose of this study was to examine the causal relationships among quality of hospital SCM (system quality, information quality, service quality), perceived usefulness, user satisfaction and logistics performance by hospital staff. Methods: A survey using a structured questionnaire was conducted with 276 hospital staff. Analysis of the data was with both SPSS Win 18.0 for descriptive statistics and AMOS 8.0 for the structural equation model. Results: The hypothetical model yielded Chi-square=8.121 (p=.087), df=4, $x^2$/df=2.030. GFI=.989, AGFI=.942, RMSEA=.066, NFI=.995, CFI=.997 TLI=.990 and showed good fit indices. Three dimensions of quality of SCM had significant direct effects on perceived usefulness. System and service of quality of SCM had significant direct effects on user satisfaction. Perceived usefulness had significant direct effects on user satisfaction. User satisfaction had significant direct effects on logistics performance. Conclusion: These results suggest that logistics performance can be enhanced by user satisfaction, user satisfaction can be enhanced by perceived usefulness, and perceived usefulness can be enhanced by quality of hospital SCM. Further study with various hospitals and various variables is necessary.

• Steel and Composite Structures
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• 제21권6호
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• pp.1369-1388
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• 2016

This study is an effort to clearly recognize the seismic damages occurred in strap-braced cold formed steel frames. In order to serve this purpose, a detailed investigation was conducted on 9 full scale strap-braced CFS walls and the required data were derived from the results of the experiments. As a consequence, quantitative and qualitative damage indices have been proposed in three seismic performance levels. Moreover, in order to assess seismic performance of the strap-braced CFS frames, a total of 8 models categorized into three types are utilized. Based on the experimental results, structural characteristics are calculated and all frames have been modeled as single degree of freedom systems. Incremental dynamic analysis using OPENSEES software is utilized to calculate seismic demand of the strap-braced CFS walls. Finally, fragility curves are calculated based on three damage limit states proposed by this paper. The results showed that the use of cladding and other elements, which contribute positively to the lateral stiffness and strength, increase the efficiency of strap-braced CFS walls in seismic events.

• 대한간호학회지
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• 제46권1호
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• pp.118-127
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• 2016

Purpose: The study purposes were to construct and test structural equation modeling on the causal relationship of community residents' perceived quality of care, image, and role performance with satisfaction, intention to (re)visit and intention to recommend hospital. Methods: A cross-sectional survey was conducted with 3,900 community residents from 39 district public hospitals. The questionnaire was designed to collected information on personal characteristics and community awareness of public hospitals. Community awareness consisted of 6 factors and 18 items. The data were collected utilizing call-interview by a survey company. Research data were collected via questionnaires and analyzed using SPSS version 20.0 and AMOS version 20.0. Results: Model fit indices for the hypothetical model were suitable for the recommended level: ${\chi}^2=796.40$ (df=79, p<.001), GFI=.93, AGFI=.90, RMSR=.08, NFI=.94. Quality of care, image, and role performance explained 68.1% of variance in community awareness. Total effect of quality of care process factors on satisfaction (path coefficients=3.67), intention to (re)visit (path coefficients=2.67) and intention to recommend hospital (coefficients=2.45) were higher than other factors. Conclusion: Findings show that public hospitals have to make an effort to improve community image through the provision of quality care, and excellent role performance. Support for these activities is available from both Central and Local Governments.

• 대한간호학회지
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• 제48권5호
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• pp.588-600
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• 2018

Purpose: The purpose of this study was to test a model of nursing competencies of nursing simulation learners. The conceptual model was based on the theory of Jeffries's simulaton theory. Methods: Data collection was conducted in October 2017 for 310 students from two nursing universities in Kyungbuk area for 20 days. Data analysis methods were covariance structure analysis using SPSS 21.0 and AMOS 22.0 statistical programs. Results: The hypothetical model was a good fit for the data. The model fit indices were comparative fit index=.97, normed fit index=.94, Tucker-Lewis Index=.97, root mean square error of approximation=.44, and standardized root mean square residual=.04. Teacher factors were directly related to simulation design characteristics, and it was confirmed that the curriculum, classroom operation and teaching method of the instructors were important factors. Learner factors were found to have a direct effect on nursing competence, self-confidence, and clinical performance that belong to nursing capacity. In particular, the results of this study indicate that the simulation design characteristics have a partial mediating effect on learner factors and clinical performance, and a complete mediating effect on learner factors and clinical judgment ability. Conclusion: In order to improve the learner's clinical performance and clinical judgment ability, it is necessary to conduct practical training through nursing simulation besides preparing the learner and the educator.