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이민후,김영석,송다희 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.3
Numerical estimation of physical properties from digital pore microstructures has drawn great attention and is being used for quantifying interrelation between various physical properties. The pore microstructures are commonly obtained by the Xray microtomographic technique, which can give fairly accurate pore geometry. However, there is minor distortion due to the limited resolution or smoothing. This distortion can cause errors in estimating physical properties by pore-scale simulation techniques. Among the properties, seismic velocity would have relatively large errors since a small amount of change in grain contacts can cause significant over-estimation. In this paper, we analyzed the errors in seismic velocity by resolution and smoothing of pore geometry using three samples: an unconsolidated sand pack and two medium-porosity sandstones with different degrees of consolidation. As the resolution becomes poor, the calculated velocity increases linearly, while smoothing gives nonlinear trends; higher errors in the early stage of smoothing. As we expected, soft rocks have higher sensitivity, since the grain contacts are small and are sensitive to minor distortion. Within similar ranges, the resolution causes larger errors than smoothing. In addition, smoothing does not cause velocity over-estimation once the resolution becomes poor, while the resolution can create considerable errors in velocity even after significant smoothing. We conclude that the resolution should be considered in the first place when obtaining digital pore microstructures to minimize errors in velocity estimation. We can also suggest that a good care should be taken when applying smoothing filters, if a sample is suspected to be poorly-consolidated or to have high porosity.
이민후,이영길,김기웅,최연철,박성식,Lee, Min-Hoo,Lee, Yung-Kil,Kim, Ki-Woong,Choi, Youn-Chul,Park, Sung-Sik 한국항공운항학회 2016 한국항공운항학회지 Vol.24 No.2
The purpose of this study is to examine the effects of human touch on turnover intention of ground handling employees at airport. Additionally, this study examines a comprehensive mediating effect of the work schedule and workload between human touch and turnover intention. To examine them, over 700 ground handling employees from six international airports of South Korea were surveyed using the simple random sampling method. The instrument for data collection was a questionnaire, and it was developed based on previous research results. The methodology adopted in this study is the structural equation modeling (SEM). According to SEM analysis, it was proven that both psychological and physical human touch have a significant effect on turnover intention of the employees. Work schedule played a mediating role among all three factors of human touch and turnover intention. However, workload has a mediating effect only between communication human touch and turnover intention. Based on the above findings, theoretical and practical implications are also discussed.