A comparative study of the adaptive choice of thresholds in extreme hydrologic events   总被引：1，自引：1，他引：0  

Myoung-Jin Um  Woncheol Cho  Jun-Haeng Heo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):611-623

In the hydrologic analysis of extreme events such as precipitation or floods, the data can generally be divided into two types: partial duration series and annual maximum series. Partial duration series analysis is a robust method to analyze hydrologic extremes, but the adaptive choice of an optimal threshold is challenging. The main goal of this paper was to determine the best method for choosing optimal thresholds. Ten semi-parametric tail index estimators were applied to find the optimal threshold of a 24-h duration precipitation period using data from the Korean Meteorological Administration. The mean square errors of the 10 estimators were calculated to determine the optimal threshold using a semi-parametric bootstrap method. A modified generalized Jackknife estimator determined the best performance in this study among the 10 estimators evaluated with regard to estimating the mean square error of the shape estimator for the generalized Pareto distribution.  相似文献   

A full Bayesian approach to generalized maximum likelihood estimation of generalized extreme value distribution   总被引：2，自引：1，他引：1  

Seonkyoo Yoon  Woncheol Cho  Jun-Haeng Heo  Chul Eung Kim 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):761-770

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Overview of geostationary ocean color imager (GOCI) and GOCI data processing system (GDPS)   总被引：4，自引：0，他引：4  

Joo-Hyung Ryu  Hee-Jeong Han  Seongick Cho  Young-Je Park  Yu-Hwan Ahn 《Ocean Science Journal》2012,47(3):223-233

GOCI, the world??s first geostationary ocean color satellite, provides images with a spatial resolution of 500 m at hourly intervals up to 8 times a day, allowing observations of short-term changes in the Northeast Asian region. The GOCI Data Processing System (GDPS), a specialized data processing software for GOCI, was developed for real-time generation of various products. This paper describes GOCI characteristics and GDPS workflow/products, so as to enable the efficient utilization of GOCI. To provide quality images and data, atmospheric correction and data analysis algorithms must be improved through continuous Cal/Val. GOCI-II will be developed by 2018 to facilitate in-depth studies on geostationary ocean color satellites.  相似文献   

Transposon mutagenesis of Psychrobacter cryohalolentis PAMC 21807 by tri-parental conjugation     

Hyu：n-Jeong Jeong  Hyoungseok Leet  Soon Gyu Hong  Jang-Cheon Cho  Hong Kum Lee  Yoo Kyung lee 《极地研究(英文版)》2013,(4):223-230

Random mutagenesis is commonly used to study gene function. The screening of mutants exhibiting specific pheno- types assists in the identification of phenotype-related genes. In the current study, we isolated Antarctic bacteria, and developed a transposon Tn5 mutagenesis system. A total of 26 strains were isolated from seawater and freshwater near Antarctic King Sejong Research Station, King George Island. Six Psychrobacter strains were identified as psychrophilic, with optimal growth tempera- tures of 10~C or 15~C Psychrobacter cryohalolentis PAMC 21807 with a high growth rate at 4~C was selected for transposon mutagenesis. Tri-parental conjugation with a plasmid containing Tn5 produced 13 putative recombinants containing the selectable marker. Genomic Southern hybridization confirmed Tn5 existed as episomes for seven recombinants, and for a single recombinant, Tn5 was integrated into the genome of Psychrobacter cryohalolentis PAMC 21807. The result indicates that the mutagenesis method, although successful, has a relatively low rate. The psychrophilic bacteria isolated in this study may be a useful resource for studying cold adaptation mechanisms, and the mutagenesis method can be applied to genetic analysis.  相似文献   

River management system development in Asia based on Data Integration and Analysis System (DIAS) under GEOSS     

Toshio Koike  Petra Koudelova  Patricia Ann Jaranilla-Sanchez  Asif Mumtaz Bhatti  Cho Thanda Nyunt  Katsunori Tamagawa 《中国科学:地球科学(英文版)》2015,58(1):76-95

This paper introduces the process of development and practical use implementation of an advanced river management system for supporting integrated water resources management practices in Asian river basins under the framework of GEOSS Asia water cycle initiative (AWCI). The system is based on integration of data from earth observation satellites and in-situ networks with other types of data, including numerical weather prediction model outputs, climate model outputs, geographical information, and socio-economic data. The system builds on the water and energy budget distributed hydrological model (WEB-DHM) that was adapted for specific conditions of studied basins, in particular snow and glacier phenomena and equipped with other functions such as dam operation optimization scheme and a set of tools for climate change impact assessment to be able to generate relevant information for policy and decision makers. In situ data were archived for 18 selected basins at the data integration and analysis system of Japan (DIAS) and demonstration projects were carried out showing potential of the new system. It included climate change impact assessment on hydrological regimes, which is presently a critical step for sound management decisions. Results of such three case studies in Pakistan, Philippines, and Vietnam are provided here.  相似文献   

Neural Network Model for Predicting the Resistance of Driven Piles     

H. I. Park  C. W. Cho 《Marine Georesources & Geotechnology》2013,31(4):324-344

Although numerous investigations have been performed over the years to predict the behavior and resistance of piles, the mechanisms are not yet entirely understood. Predicting pile resistance is a difficult task because there are a large number of parameters affecting the capacity that have complex relationships with each other. It is extremely difficult to develop appropriate relationships between various essential parameters, including the soil condition, pile type, driving condition, time effect, and others. This paper describes the application of an artificial neural network (ANN) to predict the resistance of driven piles in dynamic load tests. The training and testing of the ANN were based on 165 data points for driven piles at various construction sites in Korea. Predictions on the tip, shaft, and total pile resistance were made for piles with available corresponding measurements of such values. The effect of the essential parameters on the pile resistance values was investigated through parametric analysis using ANN modeling. The results of this study indicate that the ANN model serves as a reliable and simple predictive tool to appropriately consider various essential parameters for predicting the resistance of driven piles.  相似文献   

LPS-induced NO inhibition and antioxidant activities of ethanol extracts and their solvent partitioned fractions from four brown seaweeds     

Myoung Lae Cho  Dong-Jin Lee  Hyi-Seung Lee  Yeon-Ju Lee  Sang Guan You 《Ocean Science Journal》2013,48(4):349-359

The nitric oxide inhibitory (NOI) and antioxidant (ABTS and DPPH radical scavenging effects with reducing power) activities of the ethanol (EtOH) extracts and solvent partitioned fractions from Scytosiphon lomentaria, Chorda filum, Agarum cribrosum, and Desmarestia viridis were investigated, and the correlation between biological activity and total phenolic (TP) and phlorotannin (TPT) content was determined by PCA analysis. The yield of EtOH extracts from four brown seaweeds ranged from 2.6 to 6.6% with the highest yield from D. viridis, and the predominant compounds in their solvent partitioned fractions had medium and/or less polarity. The TP and TPT content of the EtOH extracts were in the ranges of 25.0–44.1 mg GAE/g sample and 0.2–4.6 mg PG/g sample, respectively, which were mostly included in the organic solvent partitioned fractions. Strong NOI activity was observed in the EtOH extracts and their solvent partitioned fractions from D. viridis and C. filum. In addition, the EtOH extract and its solvent partitioned fractions of D. viridis exhibited little cytotoxicity to Raw 264.7 cells. The most potent ABTS and DPPH radical scavenging capacity was shown in the EtOH extracts and their solvent partitioned fractions from S. lomentaria and C. filum, and both also exhibited strong reducing ability. In the PCA analysis the content of TPT had a good correlation with DPPH (r = 0.62), ABTS (r = 0.69) and reducing power (r = 0.65), however, an unfair correlation was observed between the contents of TP and TPT and NOI, suggesting that the phlorotannins might be responsible for the DPPH and ABTS radical scavenging activities.  相似文献   

New polymorphic microsatellite markers derived from hemocyte cDNA library of Manila clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> challenged by the protozoan parasite <Emphasis Type="Italic">Perkinsus olseni</Emphasis>     

Hyun-Sil Kang  Hyun-Ki Hong  Kyung-Il Park  Moonjae Cho  Seok-Hyun Youn  Kwang-Sik Choi 《Ocean Science Journal》2017,52(1):139-146

Manila clam Ruditapes philippinarum is one of the most important benthic animals in the coastal north Pacific region, where clam populations have been mixed genetically through trade and aquaculture activities. Accordingly, identification of the genetically different clam populations has become one of the most important issues to manage interbreeding of the local and introduced clam populations. To identify genetically different populations of clam populations, we developed 11 expressed sequence tag (EST)-microsatellite loci (i.e., simple sequence repeat, SSR) from 1,128 clam hemocyte cDNA clones challenged by the protozoan parasite Perkinsus olseni. Genotype analysis using the markers developed in this study demonstrated that clams from a tidal flat on the west coast contained 6 to 19 alleles per locus, and a population from Jeju Island had 4 to 20 alleles per locus. The expected heterozygosity of the 2 clam populations ranged from 0.472 to 0.919 for clams from the west coast, and 0.494 to 0.919 for clams from Jeju Island, respectively. Among the 11 loci discovered in this study, 7 loci significantly deviated from the Hardy-Weinberg equilibrium after Bonferroni correction. The 5 loci developed in this study also successfully amplified the SSRs of R. variegatus, a clam species taxonomically very close to R. philippinarum, from Hong Kong and Jeju Island. We believe that the 11 novel polymorphic SSR developed in this study can be utilized successfully in Manila clam genetic diversity analysis, as well as in genetic discrimination of different clam populations.  相似文献   

Estimation of net ecosystem metabolism of seagrass meadows in the coastal waters of the East Sea and Black Sea using the noninvasive eddy covariance technique     

Jae Seong Lee  Dong-Jin Kang  Elitsa Hineva  Violeta Slabakova  Valentina Todorova  Jiyoung Park  Jin-Hyung Cho 《Ocean Science Journal》2017,52(2):243-256

We measured the community-scale metabolism of seagrass meadows in Bulgaria (Byala [BY]) and Korea (Hoopo Bay [HP]) to understand their ecosystem function in coastal waters. A noninvasive in situ eddy covariance technique was applied to estimate net O₂ flux in the seagrass meadows. From the high-quality and high-resolution time series O₂ data acquired over > 24 h, the O₂ flux driven by turbulence was extracted at 15-min intervals. The spectrum analysis of vertical flow velocity and O₂ concentration clearly showed well-developed turbulence characteristics in the inertial subrange region. The hourly averaged net O₂ fluxes per day ranged from -474 to 326 mmol O₂ m^-2 d^-1 (-19 ± 41 mmol O₂ m^-2 d^-1) at BY and from -74 to 482 mmol O₂ m^-2 d^-1 (31 ± 17 mmol O₂ m^-2 d^-1) at HP. The net O₂ production rapidly responded to photosynthetically available radiation (PAR) and showed a good relationship between production and irradiance (P-I curve). The hysteresis pattern of P-I relationships during daytime also suggested increasing heterotrophic respiration in the afternoon. With the flow velocity between 3.30 and 6.70 cm s^-1, the community metabolism during daytime and nighttime was significantly increased by 20 times and 5 times, respectively. The local hydrodynamic characteristics may be vital to determining the efficiency of community photosynthesis. The net ecosystem metabolism at BY was estimated to be -17 mmol O₂ m^-2 d^-1, which was assessed as heterotrophy. However, that at HP was 36 mmol O₂ m^-2 d^-1, which suggested an autotrophic state.  相似文献   

Shear strength behavior and parameters of microbial gellan gum-treated soils: from sand to clay     

Chang  Ilhan  Cho  Gye-Chun 《Acta Geotechnica》2019,14(2):361-375

Microbial biopolymers have recently been introduced as a new material for soil treatment and improvement. Biopolymers provide significant strengthening to soil, even in small quantities (i.e., at 1/10th or less of the required amount of conventional binders, such as cement). In particular, thermo-gelating biopolymers, including agar gum, gellan gum, and xanthan gum, are known to strengthen soils noticeably, even under water-saturated conditions. However, an explicitly detailed examination of the microscopic interactions and strengthening characteristics between gellan gum and soil particles has not yet been performed. In this study, a series of laboratory experiments were performed to evaluate the effect of soil–gellan gum interactions on the strengthening behavior of gellan gum-treated soil mixtures (from sand to clay). The experimental results showed that the strengths of sand–clay mixtures were effectively increased by gellan gum treatment over those of pure sand or clay. The strengthening behavior is attributed to the conglomeration of fine particles as well as to the interconnection of fine and coarse particles, by gellan gum. Gellan gum treatment significantly improved not only inter-particle cohesion but also the friction angle of clay-containing soils.

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