Novel Extreme Learning Machine-Multi-Verse Optimization Model for Predicting Peak Particle Velocity Induced by Mine Blasting     

Zhang  Xiliang  Nguyen  Hoang  Choi  Yosoon  Bui  Xuan-Nam  Zhou  Jian 《Natural Resources Research》2021,30(6):4735-4751

Natural Resources Research - Peak particle velocity (PPV) is an important criterion for assessing the risk level of ground vibration induced by mine blasting. Based on this criterion, many efforts...  相似文献   

Generation mechanisms of convectively induced internal gravity waves in a three-dimensional framework     

Eun-Ho Choi  Hye-Yeong Chun 《Asia-Pacific Journal of Atmospheric Sciences》2014,50(2):163-177

The generation mechanisms of convective gravity waves in the stratosphere are investigated in a three-dimensional framework by conducting numerical simulations of four ideal storms under different environmental conditions: one un-sheared and three constant low-level sheared basic-state winds with the depth of the shear layer of 6 km and the surface wind speeds (U_s) of 8, 18, and 28 m s^?1, using the Advanced Regional Prediction System (ARPS) model. The storms simulated under the un-sheared (U_s = 0 m s^?1), weakly sheared (U_s = 8 and 18ms^?1), and strongly sheared (U_s = 28ms^?1) basicstate winds are classified into single-cell, multicell, and supercell storms, respectively. For each storm, the wave perturbations in a control simulation, including nonlinearity and microphysical processes, are compared with those in quasi-linear dry simulations forced by diabatic forcing and nonlinear forcing that are obtained from the control simulation. The gravity waves generated by the two forcing terms in the quasi-linear dry simulations are out of phase with each other for all of the storms. The gravity waves in the control simulation are represented by a linear sum of the wave perturbations generated by the nonlinear forcing and diabatic forcing. This result is consistent with the results of previous studies in a two-dimensional framework. This implies that both forcing mechanisms are important for generating the convective gravity waves in the three-dimensional framework as well. The characteristics of the three-dimensional gravity waves in the stratosphere were determined by the spectral combination of the forcing terms and the wave-filtering and resonance factor that is determined from the basic-state wind and stability as well as the vertical structure of the forcing.  相似文献   

Threshold value of Benthic Pollution Index (BPI) for a muddy healthy benthic faunal community and its application to Jinhae Bay in the southern coast of Korea     

Jin-Young Seo  Hyun-Sig Lim  Jin-Woo Choi 《Ocean Science Journal》2014,49(3):313-328

For the determination of benthic community health criteria of a biotic index, Benthic Pollution Index (BPI), the faunal data on macrobenthic community of Deukryang Bay collected in 2012 were used. Each macrobenthic fauna was classified into 4 functional groups according to their feeding and life history strategies and BPI was calculated using the abundance of fauna for these functional groups. Amphipods were the dominant faunal group belonging to Functional Group (FG) II in Deukryang Bay during all seasons. The BPI value fluctuated seasonally from 55 to 61, and the overall mean value of BPI in the reference area was 60, which was estimated as the threshold value for healthy communities. We tried to use BPI as an assessment tool for macrofaunal community health status by categorizing the BPI values into 5 grades. If the BPI value of the community is more than 60, the health status of a macrobenthic community will be assessed as ‘Excellent’ (Grade 1) and as ‘Good’ (Grade 2), if between 40 and 60, as ‘Fair’ (Grade 3), if between 30 and 40, as ‘Poor’ (Grade 4), if between 20 and 30, and finally the health status of a community will be assessed as ‘Very Poor’ (Grade 5), if the BPI value is less than 20. This assessment tool using BPI was applied to macrobenthic communities in Jinhae Bay including the Special Management Area of South Korea. In Jinhae Bay, the FG IV containing a spionid species, Paraprionospio patiens was the most dominant group. The values of BPI in Jinhae Bay were very low and ranged from 11 to 23. The ecological health status of macrobenthic communities in Jinhae Bay was ‘Very Poor’ at more than 50% of sites, especially in summer.  相似文献   

Cimetidine,acetaminophen, and 1,7-dimethylxanthine,as indicators of wastewater pollution in marine sediments from Masan Bay,Korea     

Minkyu Choi  Edward T. Furlong  Stephen L. Werner  Anthony S. Pait  In-Seok Lee  Hee-Gu Choi 《Ocean Science Journal》2014,49(3):231-240

Concerns have emerged regarding the presence of human-use pharmaceuticals in aquatic environments. We investigated the status of contamination by 29 human-use pharmaceuticals as well as wastewater indicator compounds, fecal sterols and the synthetic endocrine disruptor nonylphenol, in marine sediments from Masan Bay, one of the most contaminated bays in Korea as a result of untreated and/or treated sewage. Among the 29 pharmaceuticals determined, 10 including antacid, analgesic, antibiotic, and antipruritic compounds, and metabolites of caffeine and nicotine were detected in all sediment samples. Cimetidine, acetaminophen, and 1,7-dimethylxanthine were the most frequently detected pharmaceuticals (frequency > 50%), and at high concentrations. The highest concentrations and detection frequencies were at stations located close to wastewater treatment plant (WWTP) outfalls and at the river mouth. The spatial distributions of pharmaceutical were significantly correlated with those of wastewater compounds. These results indicate that occurrence of the pharmaceuticals in marine environments is likely associated with direct sewage inputs, such as WWTP effluents and with other sewage-influenced sources, such as river discharge.  相似文献   

Distribution patterns of macrobenthic fauna communities in Deukryang Bay,one of the environment conservation areas of Korea     

Jin-Young Seo  Hyun-Sig Lim  Jin-Woo Choi 《Ocean Science Journal》2014,49(2):97-113

Macrobenthic fauna were collected seasonally at 44 sites in Deukryang Bay from February to November, 2012. The species number of macrobenthic fauna was in the range of 140 to 181, and polychaetes comprised 41.4% of them. The average density of the whole study area changed seasonally from 755 to 1,507 ind. m^?2, and the most abundant fauna group was crustaceans which accounted for 55.1% of total abundance. An amphipod species Nippopisella nagatai was the most dominant species and a decapod species Xenophthalmus pinnotheroides, an amphipod species Photis longicaudata, and a polychaete species Paralacydonia paradoxa were also dominant in all seasons. The mean seasonal values of Shannon’s diversity index (H′) were in the range of 2.2–2.4, and those values for the evenness index and richness index were 0.7–0.7 and 4.6–5.7, respectively. From the cluster analysis, Deukryang Bay could be divided into 3 or 4 station groups with its specific fauna composition. The cluster analysis and an nMDS ordination revealed that local environmental factors such as water depth were related to the spatial delineation of macrobenthic fauna communities in Deukryang Bay.  相似文献   

Molecular characterization of four genes highly expressed during megalopa stage in Chinese mitten crab,Eriocheir sinensis     

Yoon  Tae-Ho  Bae  Jaeyong  Kang  Hye-Eun  Choi  Jung Hwa  Lee  Chung Il  Park  Won-gyu  Kim  Hyun-Woo 《Ocean Science Journal》2015,50(1):61-75

Ocean Science Journal - The molecular markers to distinguish different larval stages have various applications in ecological studies. Using the differential display RT-PCR technique, we isolated...  相似文献   

Changes in summer TC activity related to thermal differences between land and the sea     

Ki-Seon Choi  Baek-Jo Kim  Yu-Mi Cha  Hae-Dong Kim 《Theoretical and Applied Climatology》2015,121(3-4):479-488

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Inverse relationship between the equatorial eastern Pacific annual-cycle and ENSO amplitudes in a coupled general circulation model     

Soon-Il An  Jung Choi 《Climate Dynamics》2013,40(3-4):663-675

We propose a dynamical interpretation of the inverse relationship between the tropical eastern Pacific annual-cycle (AC) amplitude and the El Niño-Southern Oscillation (ENSO) amplitude, based on a pre-industrial simulation of Geophysical Fluid Dynamics Laboratory Couple climate model 2.0 with a fixed concentration of greenhouse gases spanning approximately 500 years. The slowly varying background conditions over more than a decade alternately provided favorable conditions for two opposite regimes, namely the ‘strong AC—weak ENSO regime’ and the ‘weak AC—strong ENSO regime’. For the weak AC—strong ENSO regime, the tropical eastern Pacific shows meridional-asymmetric surface warming with an emphasis on the southern part, leading to weakening of both the zonal trade wind and the cross equatorial southerly wind, as well as deepening of both the thermocline and mixed layer. The deeper mixed layer, weaker southerly wind, and reduced zonal gradient of the mean sea surface temperature due to tropical eastern Pacific warming all acts to reduce the AC. Conversely, the ENSO was intensified by the deeper mixed layer and deeper thermocline depth (thermocline feedback), but suppressed by the deeper thermocline depth (Ekman feedback) and the reduced zonal temperature gradient. We also computed the coupling strengths of the ENSO and AC, defined as the linear regression coefficients of the zonal and meridional wind stresses against the eastern Pacific SST, respectively. The coupling strengths of both the AC and ENSO are larger when they are intensified, and vice versa. All processes for the weak AC—strong ENSO regime operate in the opposite manner for the strong AC—weak ENSO regime.  相似文献   

Climate responses in the tropical pacific associated with atlantic warming in recent decades   总被引：2，自引：0，他引：2  

Soojin Hong  In-Sik Kang  Ildae Choi  Yoo-Geun Ham 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(2):209-217

In this study, we investigated the impact of the Atlantic decadal-scale sea surface temperature (SST) variation on the tropical Pacific climate using a Atmospheric General Circulation Model (AGCM). During the recent decade from 2000 to 2010 when the Atlantic SST has sharply increased, observations have shown that the strong easterly and increased precipitation anomalies appeared over the western-central Pacific. It is different from the conventional Gilltype response in which the easterly due to heating in the Atlantic is expected to be extended to the Indian Ocean. We have found that the warm pool over the western Pacific plays an important role in enhancing the atmospheric response to the Atlantic SST forcing in the Pacific basin. Simplified Aqua planet GCM experiments showed that the central location of the anomalous easterly over the Pacific produced by the Atlantic SST forcing highly depends on the location of the idealized warm pool. The reason for this is because the moisture feedback is strongest over the warm pool region, which leads to additional local anomalous convergence, and therefore the easterly produced by the Atlantic SST forcing is enhanced only over the east of the warm pool region.  相似文献   

Dissolved Pb Concentrations and Stable Pb Isotope Ratios in the Ulleung Basin,East/Japan Sea     

Choi  Seonghu  Choi  Man-Sik  Joe  Dongjin  Park  Sojung  Kim  Jinwoo  Ra  Kongtae  Kim  Intae  Kim  Kyung-Tae  Lee  Kyoung-Seok  Lim  Jean-Sun 《Ocean Science Journal》2022,57(3):436-450

Ocean Science Journal - The spatial distributions of dissolved lead (Pb) concentrations and stable Pb isotope ratios in the Ulleung Basin, East/Japan Sea, were investigated to identify the Pb...  相似文献