Based on communication infrastructure theory (CIT), this study developed and assessed communication concepts to understand the various ways in which residents in a metropolitan city experience and ...manage differences through their neighborhood communicative actions. We investigated three urban communities in Seoul with in-depth interviews (n = 30) and 12 focus group interview meetings (n = 120). We conceptualized two types of community storytelling actions to address differences - difference-reducing community storytelling (DRCS) and difference-managing community storytelling (DMCS). We also identified four neighborhood relational types - denial, rivalry, cohabitation, and coexistence - in the study areas as interacting in various forms with community storytelling to address the issue of difference in urban neighborhoods.
The aim of this study was to develop a new Al–Mg–Si–Zr alloy with a high magnesium content to achieve a wide range of mechanical properties using heat treatment and at a lower cost. Additive ...manufacturing was conducted using a powder bed fusion process with various scan speeds to change the volumetric energy density and establish optimal process conditions. In addition, mechanical properties were evaluated using heat treatment under various conditions. The characterization of the microstructure was conducted by scanning electron microscopy with electron backscatter diffraction and transmission electron microscopy. The mechanical properties were determined by tensile tests. The as-built specimen showed a yield strength of 447.9 ± 3.6 MPa, a tensile strength of 493.4 ± 6.7 MPa, and an elongation of 9.6 ± 1.1%. Moreover, the mechanical properties could be adjusted according to various heat treatment conditions. Specifically, under the HT1 (low-temperature artificial aging) condition, the ultimate tensile strength increased to 503.2 ± 1.1 MPa, and under the HT2 (high-temperature artificial aging) condition, the yield strength increased to 467 ± 1.3 MPa. It was confirmed that the maximum elongation (14.3 ± 0.8%) was exhibited with the HT3 (soft annealing) heat treatment.
Abstract
Under strong laser fields, electrons in solids radiate high-harmonic fields by travelling through quantum pathways in Bloch bands in the sub-laser-cycle timescales. Understanding these ...pathways in the momentum space through the high-harmonic radiation can enable an all-optical ultrafast probe to observe coherent lightwave-driven processes and measure electronic structures as recently demonstrated for semiconductors. However, such demonstration has been largely limited for semimetals because the absence of the bandgap hinders an experimental characterization of the exact pathways. In this study, by combining electrostatic control of chemical potentials with HHG measurement, we resolve quantum pathways of massless Dirac fermions in graphene under strong laser fields. Electrical modulation of HHG reveals quantum interference between the multi-photon interband excitation channels. As the light-matter interaction deviates beyond the perturbative regime, elliptically polarized laser fields efficiently drive massless Dirac fermions via an intricate coupling between the interband and intraband transitions, which is corroborated by our theoretical calculations. Our findings pave the way for strong-laser-field tomography of Dirac electrons in various quantum semimetals and their ultrafast electronics with a gate control.
A palynological study was performed using the core obtained from the Integrated Ocean Drilling Program (IODP) Expedition 346 Site U1430 in the Eastern South Korea Plateau in the East Sea, to reveal ...variability of paleoclimate and paleoceanography during the late Pliocene to early Pleistocene climate transition period (56.0–68.0 meters below sea floor mbsf). Two pollen and dinocyst zones are established with a boundary at ca. 3.0 Ma. Prior to ca. 3.0 Ma (first pollen and dinocyst zone), long-term oscillation of the East-Asian winter monsoon (EAWM) is indicated by fluctuations in the abundance of pollen taxa, representing cold–dry and cool–wet climates. After ca. 3.0 Ma (second pollen and dinocyst zone), an increase in cold–dry conifer pollen indicates an enhanced and stable EAWM. In addition, the prevalence of the xerophytic herb, Artemisia, increases markedly after 3.0 Ma, suggesting open grassland on the exposed South Yellow Sea shelf during the sea level lowstand under cold–dry climate conditions. Artemisia pollen are interpreted as having been delivered to the coast through fluvial channels in this grassland environment, and subsequently transported to the East Sea by inflow of a weak Tsushima Warm Current (TWC) through the narrow Korea Strait. The TWC intrusion signal is represented by an influx of Tuberculodinium vancampoae, a warm water dinoflagellate species, in the western Pacific region. The high abundances of cold–dry conifer pollen and cold water dinocyst elements after ca. 2.8 Ma suggest an intensified EAWM. Meanwhile, a short-term increase in moisture-loving Tsuga pollen after ca. 2.5 Ma was likely due to soil moisture derived from snowfall caused by evaporation of heated seawater from the weak TWC in the East Sea under cold climate conditions. The palynological studies reported here help verify the linkages between the EAWM, TWC, precipitation and vegetation responses in/around the East Sea region.
•Terrestrial palynomorphs (TPrelative) reflect changes in the stability of the East-Asian Monsoon.•Marine palynomorphs (TDrelative) reflect the surface water temperature of the East Sea.•Conifer pollen records show the strengthened East-Asian Winter Monsoon.•Warm dinocyst records indicate the intensity of the Tsushima Warm Current.
InP/ZnSe/ZnS quantum dots (QDs) stand as promising candidates for advancing QD-organic light-emitting diodes (QLED), but low emission efficiency due to their susceptibility to oxidation impedes ...applications. Structural defects play important roles in the emission efficiency degradation of QDs, but the formation mechanism of defects in oxidized QDs has been less investigated. Here, we investigated the impact of diverse structural defects formation on individual QDs and propagation during UV-facilitated oxidation using high-resolution (scanning) transmission electron microscopy. UV-facilitated oxidation of the QDs alters shell morphology by the formation of surface oxides, leaving ZnSe surfaces poorly passivated. Further oxidation leads to the formation of structural defects, such as dislocations, and induces strain at the oxide-QD interfaces, facilitating In diffusion from the QD core. These changes in the QD structures result in emission quenching. This study provides insight into the formation of structural defects through photo-oxidation, and their effects on emission properties of QDs.
Natural gas hydrates (GHs) filling sand layer pores are the most promising GHs that can be produced via conventional mechanisms in deep-sea environments. However, the seismic tracking of such thin ...GH-bearing sand layers is subject to certain limitations. For example, because most GH-bearing sand layers are thin and sparsely interbedded with mud layers, conventional seismic data with a maximum resolution of ~10 m are of limited use for describing their spatial distribution. The 2010 Ulleung Basin drilling expedition identified a relatively good GH reservoir at the UBGH2-6 site. However, the individual GH-bearing sand layers at this site are thin and cannot therefore be reliably tracked using conventional seismic techniques. This study presents a new thin layer tracking method using stepwise seismic inversion and 3D seismic datasets with two different resolutions. The high-resolution acoustic impedance volume obtained is then used to trace thin layers that cannot be harnessed with conventional methods. Moreover, we estimate the high-resolution regional GH distribution based on GH saturation derived from acoustic impedance at UBGH2-6. The thin GH layers, previously viewed as a single layer because of limited resolution, are further subdivided, traced, and characterized in terms of lateral variation.
Abstract
This study was to understand the genetic structure and diversity of the Korean
Malus
species. We used genotyping-by-sequencing (GBS) technology to analyze samples of 112 individuals ...belonging to 18 populations of wild
Malus
spp. Using GBS, we identified thousands of single nucleotide polymorphisms in the species analyzed.
M. baccata
and
M. toringo
, two dominant mainland species of the Korean Peninsula, were distinguishable based on their genetic structure. However,
M. toringo
collected from Jeju Island exhibited a different genetic profile than that from the mainland. We identified
M.
cf.
micromalus
as a hybrid resulting from the Jeju Island
M. toringo
(pollen donor) and the mainland
M. baccata
, (pollen recipient). Putative
M. mandshurica
distributed on the Korean Peninsula showed a high structural and genetic similarity with
M. baccata
, indicating that it might be an ecotype. Overall, this study contributes to the understanding of the population history and genetic structure of
Malus
in the Korean Peninsula.
Abstract
Phytoclasts in the form of plant debris in terrestrial sediments can be transported by water to distant areas because they are lighter than inorganic particles. The semi-enclosed East Sea, ...which is connected by narrow straits to other seas, is adjacent to continental shelves that are the source area of terrestrial sediment flowing into the East Sea. These shelves alternated repeatedly between terrestrial and marine environments as a result of eustatic sea-level changes during the Late Quaternary. Palynofacies analyses of the IODP Exp. 346 U1430 core, located in the Eastern South Korea Plateau (ESKP) of the East Sea, have revealed changes in the size and concentration of phytoclasts associated with glacial–interglacial cycles. These changes are generally negatively correlated with the global sea-level curve, and their anti-phase cycles with high amplitude are clearly evident during the last ca. 750 ka with the geotectonic stabilization period. In particular, several coarse-grained phytoclasts were observed during the glacial period, including the Last Glacial Maximum (LGM). These findings suggest that the concentration and size of phytoclasts flowing into the East Sea were influenced by changes in the distance of the source area, depending on the water depth of the strait and nearby shelves owing to sea-level changes in tandem with glacial–interglacial cycles and geotectonic events.
With the development and wide applicability of rubber materials, it is imperative to determine their performance under various conditions. In this study, the effect of cyclic shear fatigue on ...natural-rubber-based anisotropic magnetorheological elastomer (MRE) with carbonyl iron particles (CIPs) was investigated under a magnetic field. An anisotropic MRE sample was prepared by moulding under a magnetic field. Cyclic shear fatigue tests were performed using a modified electromechanical fatigue system with an electromagnet. The storage modulus (G') and loss factor in the absence or presence of a magnetic field were measured using a modified dynamic mechanical analysis system. Under a magnetic field, fatigue exhibited considerable effects to the MRE, such as migration and loss of magnetised CIPs and suppressed increase in stiffness by reducing the energy loss in the strain cycle. Therefore, the G' of the MRE after fatigue under a magnetic field was lower than that after fatigue in the zero field. The performance of the MRE, such as absolute and relative magnetorheological effects, decreased after subjecting to cyclic shear fatigue. In addition, all measured results exhibited strain-dependent behaviour owing to the Payne effect.
Abstract
Athletes cultivate highly developed muscles based on their sport category, creating a body shape that matches the characteristics of that sports category. We tested the significance of the ...correlation between muscle development characteristics and anaerobic power in athletes to build a database for each category. Fifty-eight college athletes participated in this study. To assess muscle characteristics, muscle thickness (MT) and fascicle angle (FA) were measured by ultrasonography (US) in lower limb. Furthermore, anaerobic power was measured with the Wingate test. Analysis of the correlation between muscle structure and anaerobic power revealed significant differences between the sports categories, except for the MT of the medial head of gastrocnemius (Gm), lateral head of gastrocnemius, and FA of Gm. A significant difference was observed for all parameters, except for the arrival time to peak power in the anaerobic power items; in particular, a high degree of correlation in mean power/kg and peak power/kg was observed. A similar tendency was observed in the correlation between muscle structure and anaerobic power in most sports categories, but certain muscle characteristic factors were prominent in each sport. Based on these, it is possible to contribute to predicting and promoting athletic performance.
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