5,781 research outputs found
Value Discount of Business Groups Surrounding the Asia Financial Crisis: Evidence from Korean Chaebols
Asian Financial Crisis, Business Group, Chaebol, Diversification, Firm Value
Calibration-Free Driver Drowsiness Classification based on Manifold-Level Augmentation
Drowsiness reduces concentration and increases response time, which causes
fatal road accidents. Monitoring drivers' drowsiness levels by
electroencephalogram (EEG) and taking action may prevent road accidents. EEG
signals effectively monitor the driver's mental state as they can monitor brain
dynamics. However, calibration is required in advance because EEG signals vary
between and within subjects. Because of the inconvenience, calibration has
reduced the accessibility of the brain-computer interface (BCI). Developing a
generalized classification model is similar to domain generalization, which
overcomes the domain shift problem. Especially data augmentation is frequently
used. This paper proposes a calibration-free framework for driver drowsiness
state classification using manifold-level augmentation. This framework
increases the diversity of source domains by utilizing features. We
experimented with various augmentation methods to improve the generalization
performance. Based on the results of the experiments, we found that deeper
models with smaller kernel sizes improved generalizability. In addition,
applying an augmentation at the manifold-level resulted in an outstanding
improvement. The framework demonstrated the capability for calibration-free
BCI.Comment: Submitted to 2023 11th IEEE International Winter Conference on
Brain-Computer Interfac
Nucleation and growth mechanism of ferroelectric domain-wall motion
The motion of domain walls is critical to many applications involving ferroelectric materials, such as fast high-density non-volatile random access memory. In memories of this sort, storing a data bit means increasing the size of one polar region at the expense of another, and hence the movement of a domain wall separating these regions. Experimental measurements of domain growth rates in the well-established ferroelectrics PbTiO3 and BaTiO3 have been performed, but the development of new materials has been hampered by a lack of microscopic understanding of how domain walls move. Despite some success in interpreting domain-wall motion in terms of classical nucleation and growth models, these models were formulated without insight from first-principles-based calculations, and they portray a picture of a large, triangular nucleus that leads to unrealistically large depolarization and nucleation energies. Here we use atomistic molecular dynamics and coarse-grained Monte Carlo simulations to analyse these processes, and demonstrate that the prevailing models are incorrect. Our multi-scale simulations reproduce experimental domain growth rates in PbTiO3 and reveal small, square critical nuclei with a diffuse interface. A simple analytic model is also proposed, relating bulk polarization and gradient energies to wall nucleation and growth, and thus rationalizing all experimental rate measurements in PbTiO3 and BaTiO3
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Scutellinia (Pezizales) In Korea, With A New Species and Eight New Records
Eleven species of the genus Scutellinia (Pyronemataceae, Pezizales) are recognized in Korea by analysis of macro- and micro-morphological characteristics, substrates and geographical distributions. Eight species are recorded new to Korea, namely, S. ahmadiopsis, S. badio-berbis, S. colensoi, S. jilinensis, S. nigrohirtula, S. olivascens, S. setosa and S. patagonica. Based on the exceptional length of marginal hairs and tuberculate ascospore wall ornamentation, two Korean specimens occurring on wood are described as a new species. Infraspecific morphological variations among collections within S. scutellata and S. patagonica were found. These are tentative treat as species complexes. The highly questionable occurrence of S. setosa in Asia was confirmed. Descriptions and taxonomic notes of the recognized species of Scutellinia are provided with a taxonomic key, illustrations and photographs of these species from Korea.Organismic and Evolutionary Biolog
Family Control, Product Market Competition and Firm Performance
In this paper, we try to determine the effect of the presence of family shareholders on company performance in the absence of external corporate governance. Our empirical results using Anderson et al. (2009, 2012)s family firm data suggests that family firms exhibit superior firm performance relative to nonfamily firms when the level of product market competition is weak, suggesting that the family control is an effective internal corporate governance mechanism that can compensate for weak external corporate governance. Furthermore, a family firms performance results in being superior to nonfamily firms performance in weak competitive markets, regardless of whether the CEO of a family firm is a founder, heir or professional manager. These findings suggest that the family control is an effective organizational structure in mitigating agency problems and enhancing firm performance when external corporate governance is weak
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