• Genomics & Informatics
• /
• v.17 no.4
• /
• pp.37.1-37.8
• /
• 2019

Isolation-with-migration (IM) models have become popular for explaining population divergence in the presence of migrations. Bayesian methods are commonly used to estimate IM models, but they are limited to small data analysis or simple model inference. Recently three methods, IMa3, MIST, and AIM, resolved these limitations. Here, we describe the major problems addressed by these three software and compare differences among their inference methods, despite their use of the same standard likelihood function.

• Water for future
• /
• v.26 no.1
• /
• pp.103-114
• /
• 1993

Migration characteristics with forms of channels and bed conditions are studied by constant-radius curve (CRC), sine-generated curve (SGC) and small-wave theory (SWT) method. For channels which are meandering and of which bed conditions are of coarse materials, transverse bed slope, depth and velocity distributions are predicted by CRC and SGC method, and the results are compared with measured field data, And for fine bed-materials of the sinuous channels, lateral and downvalley migration rates are computed by SWT method. It is confirmed from this investigation that transverse mass-flux factor plays significant roles in determining of magnitude and direction of meander migration.

• Environmental Engineering Research
• /
• v.23 no.4
• /
• pp.406-419
• /
• 2018

In planning public service systems such as waterworks, the design population is very important factor. Owing to the limitations of the indirect method, two new models, which take into consideration urban characteristics, were developed to accurately predict external migration rate (EMR), which is an essential component in estimating reliably the design population. The root mean square error (RMSE) between the model values and observed values were 10.12 and 15.58 for the metropolitan cities and counties respectively and were lower compared to RMSE values of 27.31 and 28.79 obtained by the indirect method. Thus, the developed models provide a more accurate estimate of EMR than the indirect method. In addition, the major influencing factors for external migration in counties were development type, ageing index, number of businesses. On the other hand, the major influencing migration factors for cities were project scale, distance to city center, manufacturing size, population growth rate and residential environment. Future medium and long-term studies would be done to identify emerging trends to appropriately inform policy making.

• Korean Journal of Materials Research
• /
• v.18 no.12
• /
• pp.673-677
• /
• 2008

Calcia (CaO) stabilized cubic-$HfO_2$ is studied by density functional theory (DFT) with generalized gradient approximation (GGA). When a Ca atom is substituted for a Hf atom, an oxygen vacancy is produced to satisfy the charge neutrality. The lattice parameter of a $2{\times}2{\times}2$ cubic $HfO_2$ supercell then increases by $0.02\;{\AA}$. The oxygen atoms closest to the oxygen vacancy are attracted to the vacancy as the vacancy is positive compared to the oxygen ion. When the oxygen vacancy is located at the site closest to the Ca atom, the total energy of $HfO_2$ reaches its minimum. The energy barriers for the migration of the oxygen vacancy were calculated. The energy barriers between the first and the second nearest sites, the second and the third nearest sites, and the third and fourth nearest sites are 0.2, 0.5, and 0.24 eV, respectively. The oxygen vacancies at the third and fourth nearest sites relative to the Ca atom represent the oxygen vacancies in undoped $HfO_2$. Therefore, the energy barrier for oxygen migration in the $HfO_2$ gate dielectric is 0.24 eV, which can explain the origin of gate dielectric leakage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.293-294
• /
• 2008

CaO stabilized cubic-$HfO_2$ is studied by using Density Functional Theory with GGA. When a Ca atom is substituted for a Hf atom, an oxygen vacancy is produced to satisfy the charge neutrality condition. When the oxygen vacancy is located at the first nearest site from the Ca atom, the total energy of $HfO_2$ is the most favorable. We calculate the energy barriers for the oxygen vacancy migration. The energy barriers between the first and the second nearest sites, the second and the third nearest sites, and the third and fourth nearest sites are 0.2, 0.5, 0.24 eV, respectively. The oxygen vacancies at the third and fourth nearest sites from the Ca atom represent the oxygen vacancies in undoped $HfO_2$. Therefore, the energy barrier for oxygen migration in $HfO_2$ gate dielectricis is 0.24eV, which can explain a leakage origin of gate dielectric.

• Geophysics and Geophysical Exploration
• /
• v.16 no.2
• /
• pp.71-78
• /
• 2013

The one-way wave equation migration is much more computationally efficient comparing with reverse time migration and it can provide better image than the migration algorithm based on the ray theory. We have developed the prestack depth migration module adopting (GS) propagator designed for vertical transverse isotropic media. Since GS propagator considers the higher-order term by expanding the Taylor series of the vertical slowness in the thin slab of the phase-screen propagator, the GS migration can offer more correct image for the complex subsurface with large lateral velocity variation or steep dip. To verify the validity of the developed GS migration module, we analyzed the accuracy with the order of the GS propagator for VTI media (GSVTI propagator) and confirmed that the accuracy of the wavefield propagation with the wide angles increases as the order of the GS propagator increases. Using the synthetic seismic data, we compared the migration results obtained from the isotropic GS migration module with the anisotropic GS migration module. The results show that the anisotropic GS migration provides better images and the improvement is more evident on steeply dipping structures and in a strongly anisotropic medium.

• Journal of Astronomy and Space Sciences
• /
• v.19 no.3
• /
• pp.181-186
• /
• 2002

We study a role of the proto-accretion disk during the formation of the planetary system, which is motivated with recent X-ray observations. There is an observational correlation of the mass of extrasolar planets with their orbital period, which also shows the minimum orbital period. This is insufficiently accounted for by the selection effect alone. Besides, most of planetary formation theories predict the lower limit of semimajor axes of the planetary orbits around 0.01 AU. While the migration theory involving the accretion disk is the most favorable theory, it causes too fast migration and requires the braking mechanism to halt the planet~0.01 AU. The induced gap in the accretion disk due to the planet and/or the truncated disk are desperately required to stop the planet. We explore the planetary evaporation in the accretion disk as another possible scenario to explain the observational lack of massive close-in planets. We calculate the location where the planet is evaporated when the mass and the radius of the planet are given, and find that the evaporation location is approximately proportional to the mass of the planet as ${m_p}^{-1.3}$ and the radius of the planet as ${r_p}^{1.3}$. Therefore, we conclude that even the standard cool accretion disk becomes marginally hot to make the small planet evaporate at~0.01 AU. We discuss other auxiliary mechanisms which may provide the accretion disk with extra heats other than the viscous friction, which may consequently make a larger planet evaporate.

• Journal of Internet Computing and Services
• /
• v.18 no.5
• /
• pp.95-102
• /
• 2017

With the development and popularization of Internet, the competition of SNS market is now getting fiercer and fiercer. SNS service providers need to keep updating their service to sustain their customers' continuance use. However, due to the homogenization of functions and services from different applications provided by different developers, there comes a new phenomenon that users shift from one SNS to another SNS. In line with this, the current study aims to explore factors affecting switching intention among SNS users by applying migration theory which explains people's migration behavior from one place to another. Findings from surveys of Korean and Chinese college students suggest that there was a difference of factors influencing switching intention among the two countries. For Korean college students, alternative attraction was the strongest factor leading to SNS switching intention. On the other hand, peer pressure was the strongest factor leading to SNS switching intention among Chinese college students.

• Journal of Contemporary Eastern Asia
• /
• v.19 no.2
• /
• pp.40-60
• /
• 2020

Among Filipino entertainers in Japan, trans women (transgender women) or transpinay (Filipino trans woman) entertainers remain understudied compared to cisgender women. Though the number of entertainers has declined, transpinay entertainers remain relevant as transgender issues continue to be salient globally. This study explains the gendered experiences of the transpinay migrants, particularly in entertainment work and their relationships, which are different from cisgender Filipino women entertainers' experiences. Using grounded theory and drawing on concepts of performativity in interactions to analyze the narratives of transpinay entertainers, I delve into how transpinay entertainers negotiate their gender and migrant identities as they establish professional and personal relationships. Moreover, the transpinays' entertainment work is a significant contributing factor to their sense of belonging in Japan, as they form relationships with colleagues, clients, and partners who support them and, thereby, sustain their lifestyles as trans women. The transpinay entertainers' flows of migration between Japan and the Philippines reveal that they embrace various aspects of social remittances and use them to their advantage to create and enhance their transpinay identity in Japan. By examining the transpinays' migrant experiences, this study aims to elucidate the gendered experiences of transpinay entertainers, which involve significant negotiations in their migration pathways notably different from cisgender Filipino women entertainers, reveal resilience.

• Journal of the Korean Ceramic Society
• /
• v.53 no.3
• /
• pp.301-305
• /
• 2016

We investigate proton conduction in a nonstoichiometric ${\Sigma}3$ $BaZrO_3$ (210)[001] tilt grain boundary using density functional theory (DFT). We employ the space charge layer (SCL) and structural disorder (SD) models with the introduction of protons and oxygen vacancies into the system. The segregation energies of proton and oxygen vacancy are determined as -0.70 and -0.54 eV, respectively. Based on this data, we obtain a Schottky barrier height of 0.52 V and defect concentrations at 600K, in agreement with the reported experimental values. We calculate the energy barrier for proton migration across the grain boundary core as 0.61 eV, from which we derive proton mobility. We also obtain the proton conductivity from the knowledge of proton concentration and mobility. We find that the calculated conductivity of the nonstoichiometric grain boundary is similar to those of the stoichiometric ones in the literature.