• Geomechanics and Engineering
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• v.36 no.1
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• pp.83-97
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• 2024

It is important to make reasonable prediction about the long-term deformation of high rockfill geostructures. However, the deformation is usually underestimated using the rockfill parameters obtained from laboratory tests due to different size effects, which make it necessary to identify parameters from in-situ monitoring data. This paper proposes a novel hybrid back-analysis method with a modified objective function defined for the time-dependent back-analysis problem. The method consists of two stages. In the first stage, an improved weighted average method is proposed to quickly narrow the search region; while in the second stage, an adaptive response surface method is proposed to iteratively search for the satisfactory solution, with a technique that can adaptively consider the translation, contraction or expansion of the exploration region. The accuracy and computational efficiency of the proposed hybrid back-analysis method is demonstrated by back-analyzing the long-term deformation of two high embankments constructed for airport runways, with the rockfills being modeled by a rheological model considering the influence of stress states on the creep behavior.

• Research in Community and Public Health Nursing
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• v.31 no.1
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• pp.34-42
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• 2020

Purpose: The objective of this study was to identify whether spirituality mediates the relationship between empathy and elderly care performance among Long Term Care (LTC) hospitals nurses in Korea. Methods: The data collection was performed July 1st to August 31th, 2018. Participants were 119 nurses from three long-term care hospitals in Korea. Self-reported questionnaires were administered to assess general characteristics, empathy, spirituality and elderly care performance. The data were analyzed using descriptive statistics, t-test, one-way ANOVA, Pearson's correlation coefficients, and three-stage simple and multiple regression analysis as proposed by Baron and Kenny. Results: The level of elderly care performance of participants was significantly different based on age (F=3.92, p=.010) and nurse's position (t=-2.18, p=.031). Spirituality had a significant mediating effect on the relationship between empathy and elderly care performance (Z=3.64, p<.001). Conclusion: As spirituality completely mediates the relationship between empathy and elderly care performance, it is necessary to develop a nursing education program that applies spirituality and empathy and supports religious activities at an institutional level.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.4
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• pp.169-181
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• 2007

This paper investigated the role of transportation in increasing logistics service quality and effect of logistics service quality on the long term orientation of the supply chain partnership. Four primary dimensions were identified through a comprehensive literature review. The common dimensions included information sharing, the sharing of risks and rewards, cooperative continuous improvements on cost reductions and increased quality. The results of the data analysis indicated that transportation were perceived to play an important role in logistics service quality that effecting on the long term orientation. This provides useful insight for making further conclusions concerning the actual roles of transportation within partnerships.

• Computers and Concrete
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• v.31 no.2
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• pp.85-95
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• 2023

Natural pozzolans are used as additives in cement to develop more durable and high-performance concrete. Pozzolanic activity index (PAI) is important for assessing the performance of a pozzolan as a binding material and has an important effect on the compressive strength, permeability, and chemical durability of concrete mixtures. However, the determining of the 28 days (short term) and 90 days (long term) PAI of concrete mixtures is a time-consuming process. In this study, to reduce extensive experimental work, it is aimed to predict the short term and long term PAIs as a function of the chemical compositions of various natural pozzolans. For this purpose, the chemical compositions of various natural pozzolans from Central Anatolia were determined with X-ray fluorescence spectroscopy. The mortar samples were prepared with the natural pozzolans and then, the short term and the long term PAIs were calculated based on compressive strength method. The effect of the natural pozzolans' chemical compositions on the short term and the long term PAIs were evaluated and the PAIs were predicted by using multiple linear regression (MLR) and adaptive neuro-fuzzy inference system (ANFIS) model. The prediction model results show that both reactive SiO₂ and SiO₂+Al₂O₃+Fe₂O₃ contents are the most effective parameters on PAI. According to the performance of prediction models determined with metrics such as root mean squared error (RMSE) and coefficient of correlation (R²), ANFIS models are more feasible than the multiple regression model in predicting the 28 days and 90 days pozzolanic activity. Estimation of PAIs based on the chemical component of natural pozzolana with high-performance prediction models is going to make an important contribution to material engineering applications in terms of selection of favorable natural pozzolana and saving time from tedious test processes.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.1033-1040
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• 1995

To simulate strength reliability and durability of ceramic parts under gas turbine application environments, particle impact damage behaviors in silicon carbide oxidized at 1673 K and 1523 K for 200 hours in atmosphere were investigated. The long-term oxidation produced a slight increase in the static fracture strength. Particle impact caused a spalling of oxide layer. The patterns of spalling and damage induced were dependent upon the property and impact velocity of the particle. Especially, the difference in spalling behaviors induced could be explained by introducing the formation mechanism of lateral crack and elastic-plastic deformation behavior at impact sit. At the low impact velocity regions, the oxidized SiC showed a little increase in the residual strength due to the cushion effect of oxide layer, as compared with the as-received SiC without oxide layer.

• Journal of Information Technology Services
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• v.11 no.2
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• pp.307-317
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• 2012

We investigate the long-term effect of servitization strategy on firm value. Manufacturing companies recognize servitization as their competitive strategies. While most of existing literature have focused on developing theory, presenting framework, or cases, only a few papers examine effects of servitization strategy empirically. We aims to empirically test the long-term relationship between servitization strategy and firm value. Service ratio and Tobin's q are used to measure the degree of servitization and firm performance, respectively. Data set covers 130 manufacturing companies for 12 years from 1998 to 2009.

• Journal of The Korean Astronomical Society
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• v.19 no.2
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• pp.91-107
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• 1986

Making use of our extended version of $\ddot{O}pik's$ convection theory, we have calculated magnetic cycle periods of the sun and late type stars by using Parker's dynamo theory, where we have included the non-linear effect. We presented a relationship between the computed cycle period and spectral type to analyze observed magnetic activities of the late type stars and long-term luminosity variations. It is found that (1) the stellar magentic-cycle period increases towards the later spectral type, (2) the rapid rotation facilitates the activity-related luminosity variation of stars later than about K5, (3) differential rotation plays a critical role in determining the magnetic activity-cycle period, and (4) the non-local effect should be taken into account in order to understand the observed long-term luminosity variations.

• Journal of Distribution Research
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• v.4 no.1
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• pp.93-122
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• 1999

Long-term relationship in distribution channels has been emphasized in the former researches. But many researches and literatures have not focused on how to achieve and maintain long-term relationship. To achieve and maintain long-term relationship, this study pays attention to the role of trust and commitment. The purpose of this study is explaining the relation between trust and commitment with the mutual perspectives of retailer and supplier. Research results indicate that trust has an effect on commitment, trust has two levels of firm and a responsible person, and perception of partners commitment has an effect on trust in two levels. And it shows that to increase perception of commitment, increasing commitment, quality of communication, satisfaction, reputation, and decreasing opportunistic behavior should be considered.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.4
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• pp.154-163
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• 2020

The pilot's aeronautical decision-making during the flying greatly affects flight safety, and the importance of situational awareness has been greatly emphasized as a prerequisite for making the right decision. This is the reason why more research and interests are needed to help students entering the pilot training program develop excellent situational awareness from the initial stage of training. Situational awareness is closely related to long-term memory activities in human information processing, and pedagogy and cognitive psychology have emphasized the encoding techniques as an effective long-term memory method. This study was conducted to confirm whether pilot students' using the encoding techniques to learn flight education materials in the early stage of their training at domestic universities has a positive effect on improving their situational awareness.

• Smart Structures and Systems
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• v.19 no.2
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• pp.137-149
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• 2017

Under the interference of the temperature effect, the alternation of cable force due to damages of a cable-stayed bridge could be difficult to distinguish. Considering the convenience and applicability in engineering practice, simple air or cable temperature measurements are adopted in the current study for the exclusion of temperature effect from the variation of cable force. Using the data collected from Ai-Lan Bridge located in central Taiwan, this work applies the ensemble empirical mode decomposition to process the time histories of cable force, air temperature, and cable temperature. It is evidently observed that the cable force and both types of temperature can all be categorized as the daily variation, long-term variation, and high-frequency noise in the order of decreasing weight. Moreover, the correlation analysis conducted for the decomposed variations of all these three quantities undoubtedly indicates that the daily and long-term variations with different time shifts have to be distinguished for accurately evaluating the temperature effect on the variation of cable force. Finally, consistent results in reducing the range of cable force variation after the elimination of temperature effect confirm the validity and stability of the developed method.