Mangerite magmatism associated with a probable Late-Permian to Triassic Hongseong–Odesan collision belt in South Korea     

Chang Whan Oh  Sajeev Krishnan  Sung Won Kim  Yong Wan Kwon 《Gondwana Research》2006,9(1-2):95

The Odesan area in the eastern Gyeonggi Massif, South Korea, consists principally of migmatitic and porphyroblastic gneisses intruded by mangerite. Mafic mangerites with SiO₂ contents from 52.40 to 54.20 wt.% have higher FeO* + MgO (14.98–18.28 wt.%) and CaO contents (5.80–7.84 wt.%) but lower total alkali contents (4.74 < Na₂O + K₂O < 5.80 wt.%) than felsic mangerites (55.9 < SiO₂ < 60.61 wt.%, 9.51< FeO* + MgO < 11.62 wt.%, 3.28 < CaO < 5.68 wt.%, 6.72 < Na₂O + K₂O < 8.05 wt.%). Fe-numbers (FeO* / [MgO + FeO*]) are 0.44–0.47 for mafic mangerites and 0.38–0.42 for felsic mangerites. The mangerites show calc-alkaline affinities in an AFM plot and resemble high-Ba–Sr granitoids with low Rb / Sr ratios of 0.25–0.10. Their MORB-normalized compositions show enrichment in LILE (decoupled LIL/HFS pattern) and negative anomalies in Ti–Nb–Ta. Their geochemical characters are consistent with their formation by partial melting of a basaltic source at temperatures higher than 1025 °C. The mangerites of the present study differ from mangerite formed in a typical within-plate tectonic setting in their high mg# and Sr concentrations and negative Nb and Ta anomalies. Their LILE enrichment and negative Ti–Nb–Ta anomalies could well have been inherited from a pre-collision subduction event. A mean U–Pb zircon age of 257 Ma for the mangerite demonstrates that the tectonic belt connecting the Hongseong and Odesan areas represents a probable extension of the late Permian–Triassic collision belt between the North China and South China blocks into South Korea, with collision occurred earlier in South Korea.  相似文献   

Multi-resolution Hybrid Data Assimilation Core on a Cubed-sphere Grid (HybDA)     

Hyo-Jong Song  Ji-Hyun Ha  In-Hyuk Kwon  Junghan Kim  Jihye Kwun 《Asia-Pacific Journal of Atmospheric Sciences》2018,54(1):337-350

This study illustrates the characteristics of the data assimilation system at the Korea Institute of Atmospheric Prediction Systems (KIAPS), based on the cubed-sphere grid system. The most interesting feature is the use of spherical harmonic functions defined on cubed-sphere grid points, which makes it possible to control the allowable physical wavenumber for the analysis increments. The relevant computational costs and parallel scalability are represented. The multiple-resolution approach is a distinguishable aspect of this data assimilation system. The wavenumber, up to which the analysis is conducted, increases as the outer iteration progresses. This multiresolution strategy is based on an investigation into the change of spectral components of analysis increments. The multi-resolution outer-loop provides cost-effective analysis-improvement, by explicitly controlling the analysis increments entered into the observation operator. To utilize the high-resolution deterministic forecast as a background state, it is subtracted from the forecast ensemble, to produce ensemble forecast perturbation that is hybridized with static background error covariance. Based on the cycled analysis experiments, the higher-resolution deterministic forecast is shown to preserve the high-frequency feature of the analysis increment relative to the ensemble mean forecast.  相似文献   

Effects of building-roof cooling on flow and air temperature in urban street canyons     

Jae-Jin Kim  Eric Pardyjak  Do-Yong Kim  Kyoung-Soo Han  Byung-Hyuk Kwon 《Asia-Pacific Journal of Atmospheric Sciences》2014,50(3):365-375

The effects of building-roof cooling on flow and air temperature in 3D urban street canyons are numerically investigated using a computational fluid dynamics (CFD) model. The aspect ratios of the building and street canyon considered are unity. For investigating the building-roof cooling effects, the building-roof temperatures are systematically changed. The traditional flow pattern including a portal vortex appears in the spanwise canyon. Compared with the case of the control run, there are minimal differences in flow pattern in the cases in which maximum building-roof cooling is considered. However, as the building roof becomes cooler, the mean kinetic energy increases and the air temperature decreases in the spanwise canyon. Building-roof cooling suppresses the upward and inward motions above the building roof, resultantly increasing the horizontal velocity near the roof level. The increase in wind velocity above the roof level intensifies the secondarily driven vortex circulation as well as the inward (outward) motion into (out of) the spanwise canyon. Finally, building-roof cooling reduces the air temperature in the spanwise canyon, supplying much relatively cool air from the streamwise canyon into the spanwise canyon.  相似文献   

Modeling the changes in the concentration of aromatic hydrocarbons from an oil-coated gravel column     

Jee-Hyun Jung  Hyun-Joong Kang  Moonkoo Kim  Un Hyuk Yim  Joon Geon An  Won Joon Shim  Jung-Hwan Kwon 《Ocean Science Journal》2015,50(4):763-773

The performance of a lab-scale flow-through exposure system designed for the evaluation of ecotoxicity due to oil spills was evaluated. The system simulates a spill event using an oil-coated gravel column through which filtered seawater is passed and flows into an aquarium containing fish embryos of olive flounder (Paralichthys olivaceus) and spotted sea bass (Lateolabrax maculates). The dissolved concentrations of individual polycyclic aromatic hydrocarbons (PAHs) in the column effluent were monitored and compared with theoretical solubilities predicted by Raoult’s law. The effluent concentrations after 24 and 48 h were close to the theoretical predictions for the higher molecular weight PAHs, whereas the measured values for the lower molecular weight PAHs were lower than predicted. The ratios of the concentration of PAHs in flounder embryos to that in seawater were close to the lipid-water partition coefficients for the less hydrophobic PAHs, showing that equilibrium was attained between embryos and water. On the other hand, 48 h were insufficient to attain phase equilibrium for the more hydrophobic PAHs, indicating that the concentration in fish embryos may be lower than expected by equilibrium assumption. The results indicate that the equilibrium approach may be suitable for less hydrophobic PAHs, whereas it might overestimate the effects of more hydrophobic PAHs after oil spills because phase equilibrium in an oil-seawater-biota system is unlikely to be achieved. The ecotoxicological endpoints that were affected within a few days are likely to be influenced mainly by moderately hydrophobic components such as 3-ring PAHs.  相似文献   

Global spectral energy distributions of the Large Magellanic Cloud with interstellar dust     

Sungeun Kim  Eunjoo Kwon  Kyoung-Sook Jeong  Kihun Kim  Chiyoung Cho  Eun Jung Chung 《Astrophysics and Space Science》2014,349(1):423-435

The effects of dust on infrared emission vary among galaxies of different morphological types. We investigated integrated spectral energy distributions (SEDs) in infrared and submillimeter/millimeter emissions from the Large Magellanic Cloud (LMC) based on observations from the Herschel Space Observatory (HSO) and near- to mid-infrared observations from the Spitzer Space Telescope (SST). We also used IRAS and WMAP observations to constrain the SEDs and present the results of radiative transfer calculations using the spectrophotometric galaxy model. We explain the observations by using dust models with different grain size distributions in the interstellar medium of the LMC, noting that the LMC has undergone processes that differ from those in the Milky Way. We determined a spectral index and a normalization factor in the range of ?3.5 to ?3.45 with grain radii in the range of 1 nm–300 nm for the silicate grain and 2 nm–1 μm for the graphite grain. The best fit to the observed SED was obtained with a spectral index of ?3.47, similar to the value derived by Piovan et al. (Mon. Not. R. Astron. Soc. 366(3):923, 2006a). The grain size distribution is described using a power law but with a break that is introduced below a _b , where a larger exponent is used. Changing the graphite grain size distribution significantly changed the SED pattern within the observational uncertainties. Based on the SED fits to the observations from submillimeter wavelengths to infrared radiation from the LMC using GRASIL (Silva et al., Astrophys. J. 509(1):103, 1998), we obtained a reasonable set of parameter values in chemical and geometric space together with the grain size distributions (Weingartner and Draine, Astrophys. J. 548(1):296, 2001) and a modified MRN model with the LMC extinction curve (Piovan et al., Mon. Not. R. Astron. Soc. 366(3):923, 2006a). For a given set of parameters including the disc scale height, synthesis of the starlight spectrum, optical depth, escape time scale, dust model, and star formation efficiency, the adopted dust-to-gas ratio for modeling the observed SEDs, ～1/300 (from the literature) yields a reasonable fit to the observed SEDs and similar results with the metallicity of the LMC as those reported in Russell and Bessell (Astrophys. J. Suppl. Ser. 70:865, 1989). The dust-to-gas ratios that are given as the metallicity caused the variation in the model fits. The difference mainly appears at the wavelengths near 100 μm.  相似文献   

Effects of environmental and biological conditions on the recruitment and growth of the Manila clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> on the west coast of Korea     

Sang Lyeol Kim  Soon Hyun Kwon  Hyung-Gon Lee  Ok Hwan Yu 《Ocean Science Journal》2017,52(1):91-101

The distribution of the Manila clam Ruditapes philippinarum, which is often dominant in intertidal zones, is influenced by both environmental and biological conditions. However, there have been few comprehensive studies on the interactive effects of these two groups of factors. The present study examined the environmental and biological parameters determining the population dynamics of the clams that is a dominant component of the intertidal communities of Euhangri and Padori on the west coast of Korean peninsula. We collected R. philippinarum and other members of the macrobenthos (> 1 mm long) monthly from 0.25 m² quadrats deployed in the intertidal zones at Euhangri, Taean, and Padori during the period from August 2013 to January 2015. Physicochemical parameters of the water and sediment were measured at the same time. Water temperature and salinity is high and low in the summer to winter, respectively. While mean grain size of the sediment was higher at Euhangri than at Padori, total mean density of R. philippinarum was higher at Euhangri (325 ind./ 0.25 m² at Padori vs. 194 ind./0.25 m² at Euhangri). Settled spat (< 10 mm in length) density was much higher at Euhangri than at Padori (132 vs. 12 individuals/0.25m², respectively). R. philippinarum spats settled down on the sediment at Euhangri in October and grew continually until the following May, when they reached adult size. Spats that settled down at Padori between March and April were not able to reach the adult stage. As the density of the adult population increased, the condition index of individual clams decreased, but as the population density of the spat increased the body condition index increased. The chlorophyll a content of the sediments at Padori exceeded that at Euhangri and decreased as the population of R. philippinarum increased. The shapes of R. philippinarum shells at Euhangri were more prolate than those at Padori, and the condition index at Euhangri exceeded that at Padori, indicating better growth conditions at Euhangri. The condition index and density of R. philippinarum were affected by the amount of chlorophyll a in the water column and in the sediment. The recruitment success of spats was negatively influenced by spat density. We suggest that regulation of habitat conditions for R. philippinarum, including the food supply, will optimize production of these commercial clams.  相似文献   

Influence of frequency‐dependent soil–structure interaction on the fragility of R/C bridges          下载免费PDF全文

Nikolaos Lesgidis  Anastasios Sextos  Oh‐Sung Kwon 《地震工程与结构动力学》2017,46(1):139-158

Bridge performance under earthquake loading can be significantly influenced by the interaction between the structure and the supporting soil. Even though the frequency dependence of the interaction mentioned in this study has long been documented, the simplifying assumption that the dynamic stiffness is dominated by the mean or predominant excitation frequency is still commonly made, primarily as a result of the associated numerical difficulties when the analysis has to be performed in the time domain. This study makes use of the advanced lumped parameter models recently developed 1 in order to quantify the impact of the assumption on the predicted fragility of bridges mentioned in this study. This is achieved by comparing the predicted vulnerability for the case of a reference, well studied, actual bridge using both conventional, frequency‐independent, Kelvin–Voigt models and the aforementioned lumped parameter formulation. Analysis results demonstrate that the more refined consideration of frequency dependence of soil–structure interaction at the piers and the abutments of a bridge not only leads to different probabilities of failure for given intensity measures but also leads to different hierarchy and distribution of damage within the structure for the same set of earthquake ground motions even if the overall probability of exceeding a given damage state is the same. The paper concludes with the comparative assessment of the effect for different soil conditions, foundation configurations, and ground motion characteristics mentioned in this study along with the relevant analysis and design recommendations. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Pre- and post-earthquake regional loss assessment using deep learning     

Taeyong Kim  Junho Song  Oh-Sung Kwon 《地震工程与结构动力学》2020,49(7):657-678

As urban systems become more highly sophisticated and interdependent, their vulnerability to earthquake events exhibits a significant level of uncertainties. Thus, community-level seismic risk assessments are indispensable to facilitate decision making for effective hazard mitigation and disaster responses. To this end, new frameworks for pre- and post-earthquake regional loss assessments are proposed using deep learning methods. First, to improve the accuracy of the response prediction of individual structures during the pre-earthquake loss assessment, a widely used nonlinear static procedure is replaced by the recently developed probabilistic deep neural network model. The variabilities of the nonlinear responses of a structural system given the seismic intensity can be quantified during the loss assessment process. Second, to facilitate near-real-time post-earthquake loss assessments, an adaptive algorithm, which identifies the optimal number and locations of sensors in a given urban area, is proposed. Using a deep neural network that estimates area-wide structural damage given the spatial distribution of the seismic intensity levels as a surrogate model, the algorithm adaptively places additional sensors at property lots at which errors from surrogate estimations of the structural damage are the greatest. Note that the surrogate model is constructed before earthquake events using simulated datasets. To test and demonstrate the proposed frameworks, the paper introduces thorough numerical investigations of two hypothetical urban communities. The proposed frameworks using the deep learning methods are expected to make critical advances in pre- and post-earthquake regional loss assessments.  相似文献