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51.
Storm surge prediction using an artificial neural network model and cluster analysis 总被引:1,自引:1,他引:0
In this study, an artificial neural network model was developed to predict storm surges in all Korean coastal regions, with
a particular focus on regional extension. The cluster neural network model (CL-NN) assessed each cluster using a cluster analysis
methodology. Agglomerative clustering was used to determine the optimal clustering of 21 stations, based on a centroid-linkage
method of hierarchical clustering. Finally, CL-NN was used to predict storm surges in cluster regions. In order to validate
model results, sea levels predicted by the CL-NN model were compared with results using conventional harmonic analysis and
the artificial neural network model in each region (NN). The values predicted by the NN and CL-NN models were closer to observed
data than values predicted using harmonic analysis. Data such as root mean square error and correlation coefficient varied
only slightly between CL-NN and NN model results. These findings demonstrate that cluster analysis and the CL-NN model can
be used to predict regional storm surges and may be used to develop a forecast system. 相似文献
52.
Physicochemical characteristics relevant to the adsorption of MTBE and Cd on three types of clay minerals were investigated.
The characteristics were examined through batch adsorption tests conducted under various experimental conditions such as adsorption
time, ratio of solution-to soil, concentration of solutes, concentration of organic matters, pH, and zeta potential. The adsorption
efficiency of MTBE or Cd on three types of clays decreased in response to an increase of the ratio of solution-to-soil; nevertheless,
the adsorbed amounts inversely increased. MTBE was adsorbed on clays in an increasing order of vermiculite, bentonite, and
CTAB-bentonite. However, Cd was adsorbed in a different order of bentonite, vermiculite, and CTAB-bentonite. The adsorption
of MTBE was well fitted with the Freundlich model, whereas the Cd was more closely suited to a Langmuir equation. By adding
humic acids of 1 and 5%, MTBE was significantly adsorbed on bentonite and vermiculite, respectively, but beyond that, its
adsorption was diminished. In comparison, the adsorption on CTAB-bentonite was increased in proportion to the humic acids
addition. Likewise, the addition of humic acids acted to increase the adsorption of Cd regardless of the types of adsorbent,
where up to 90% of Cd was removed at pH 10. Further increase of pH declined the degree of zeta potential, while increasing
Cd concentration also lowered the zeta potential, which consequently contributes in enhancing the adsorption efficiency of
Cd on clays. 相似文献
53.
Bioturbation, especially sediment reworking by the activities of macroinvertebrates, such as feeding and burrowing, is one of the major processes that affect the physical, chemical, and biological characteristics of marine sediments. Given the importance of sediment reworking, this study was designed to evaluate the sediment reworking rate of a polychaete, Perinereis aibuhitensis, which is dominant in the upper tidal flats on the west coast of Korea, based on quantification of pellet production during spring and fall surveys. The density of individuals was higher in fall than in spring, whereas, due to a difference in the proportion of adults between the two seasons, the morphometric dimensions of the worm and its pellets were significantly longer and heavier in the spring. Hourly pellet production per inhabitant and density were closely related, with pellet production gradually decreasing as density increased. Daily pellet production was much higher in spring than in fall, mostly due to an increase in daytime production. The sediment reworking rate of Perinereis was similar in the two seasons in which observations were made and depended on its density and the sediment reworking rate per individual. The overall sediment reworking rate of Perinereis was 31 mm yr?1 based on its density in the study area. 相似文献
54.
In Korea, the new permission criteria for industrial effluents based on Daphnia magna acute toxicity tests will be gradually implemented starting from 2011. Thus, in this study, toxicity assessment and identification using a marine species (Tigriopus japonicus) and the freshwater species (D. magna) was comparatively investigated. Effluent from an acid mine drainage treatment plant showed acute toxicity toward both organisms due to low pH, which was removed by neutralization of the effluent. Additionally, evaluation of the effluent of an electronics company revealed that Cu was attributable to the observed toxicity, and the effluent was more toxic toward T. japonicus than D. magna. Moreover, effluents from a metal plating factory were acutely toxic toward D. magna (6.50 TU), while they were not toxic against T. japonicus. Toxicity identification revealed that the high level of Cl- (12,841 mg L(-1)) was the cause of toxicity. Thus, the effluents had no effect on the marine species, T. japonicus. These findings suggest that a marine species rather than a freshwater species is more desirable for toxicity assessment of industrial effluent discharged into the saltwater, and thus should be considered in the legislation of toxicity-based discharge limits in Korea. 相似文献
55.
Jae-Hoon Cha Kwang-Bae Kim Ji-Na Song In-Soo Kim Jeong-Bin Seo Chul-Hwi Kwoun 《Ocean Science Journal》2013,48(4):319-328
This study was carried out to learn about differences in the sessile macrobenthic fauna communities between the artificial and natural habitats. There were some differences in terms of species composition and dominant species and community structure between two habitat types. The dominant species include Pollicipes mitella and Granuilittorina exigua in natural rocky intertidal zones; Monodonta labio confusa, Ligia exotica, Tetraclita japonica in the artificial rocky intertidal zones. Among all the species, L. exotica and T. japonica occurred only in the artificial rocky intertidal zone. The results of cluster analysis and nMDS analysis showed a distinct difference in community structure between artificial and natural rocky intertidal zones. The fauna in the natural rocky intertidal zones were similar to each other and the fauna in the artificial rocky intertidal zones were divided depending on the slope of the substratum. In the case of a sloping tetrapod, M. labio confusa and P. mitella were dominant, but at the vertical artificial seawall, Cellana nigrolineata, L. exotica T. japonica were dominant. The analysis of the species presented in natural and artificial rocky intertidal areas showed the exclusive presence of 10 species on natural rocks and 12 species on artificial rocks. The species in the natural rocky intertidal area included mobile gastropods and cnidarians (i.e. rock anemones), and the species in the artificial rocky intertidal area mostly included non-mobile attached animals. The artificial novel structure seems to contribute to increasing the heterogeneity of habitats for marine invertebrate species and an increase the species diversity in rocky coastal areas. 相似文献
56.
S. Niggol Seo 《Climatic change》2013,121(2):115-124
The impact of climate change on US agriculture has been debated for more than two decades, but the estimates ranged from no damage at the lower end to 80 % losses of grain yields at the higher end. This essay aims to help understand such divergent predictions by clarifying the concepts of weather and climate. First, the widely-read panel fixed effects models capture only the impacts of weather fluctuations but not of climate normals. Random weather fluctuations and climatic shifts are two different meteorological events and they have distinct implications on farming decisions. The former is perceived as random while the latter is perceived as non-random by the farmers. Using the historical corn yield data in the US, I explain the differences between the impact of random weather and that of climate change. Second, adaptation strategies to climatic changes and increased climate risks cannot be accounted for by the panel fixed effects models. Using the farm household data collected in sub-Saharan Africa and Latin America, I discuss quantitative significance of modeling adaptation strategies in the estimates of climate damage. Distinction between random weather fluctuations and climatic shifts is critical in modeling farming decisions, as they are fundamental to climate science, but is poorly understood by the impact researchers. 相似文献
57.
Rozbeh B. Moghaddam William D. Lawson James G. Surles Hoyoung Seo Priyantha W. Jayawickrama 《Geotechnical and Geological Engineering》2017,35(5):2147-2162
This study analyzes blowcount data from instrumented Texas Cone Penetration (TCP) tests. TCP hammer efficiency, rod length influence on the hammer efficiency, and overburden pressure correction factors for the TCP blowcounts (NTCP) are explored. Results are compared to published correction factors for the standard penetration test (SPT). The final dataset analyzed for this study consisted of 293 TCP tests from which 135 tests were instrumented. TCP hammer efficiency values for automatic trip hammers ranged from 74 to 101% with an average of 89%. Analyses showed a statistically-significant relationship between the TCP hammer efficiency and the rod length below ground surface. Statistical models were developed for undifferentiated soils, and corresponding rod length correction factors for the TCP test (CR-TCP) were obtained ranging from 0.90 to 1.00. In a second analysis, the relationship between the overburden pressure and NTCP was explored and a mathematical expression for the overburden correction factor for the TCP blowcount value (CN-TCP) was determined. This work represents the first study where corrections to NTCP are explored, and the outcome of this research benefits the geotechnical engineering community using the TCP test and its associated foundation design method. 相似文献
58.
LUMBRES Roscinto Ian Canicosa LEE Young Jin CHOI Hyung Soon KIM Sung Yong JANG Mi Na ABINO Azyleah Caizares SEO Yeon Ok KIM Chan Soo PARK Jung Hwan 《山地科学学报》2014,11(2):442-448
This study was conducted to fit the diameter-height data of Quercusglaucain Jeju Island, South Korea to the four commonly used stem taper equations andto evaluate the performance of the four stem taper models using four statistical criteria: Fit index (FI), root mean square error (RMSE), bias (),and absolute mean difference (AMD). Results showed that the Kozak02stem taper equation provided the best FI(0.9847), RMSE(1.5745),(-0.0030 cm) and AMD (1.0990 cm) whileMax and Burkhart model had the poorest performance among the four stem taper models based on the four evaluation statistics (FI : 0.9793,RMSE : 1.8272, : 0.3040 cm and AMD : 1.3060 cm). These stem taper equations can serve as a useful tool for forest managers in estimating the diameter outside bark at any given height, merchantable stem volumes and total stem volumesof the standing trees of Quercusglaucain theGotjawal forests located in Mount Halla, Jeju Island, South Korea. 相似文献
59.
Jin-Yong Kim Kyong-Hwan Seo Jun-Hyeok Son Kyung-Ja Ha 《Asia-Pacific Journal of Atmospheric Sciences》2017,53(2):207-216
An ensemble statistical forecast scheme with a one-month lead is developed to predict year-to-year variations of Changma rainfall over the Korean peninsula. Spring sea surface temperature (SST) anomalies over the North Atlantic, the North Pacific and the tropical Pacific Ocean have been proposed as useful predictors in a previous study. Through a forward-stepwise regression method, four additional springtime predictors are selected: the northern Indian Ocean (NIO) SST, the North Atlantic SST change (NAC), the snow cover anomaly over the Eurasian continent (EUSC), and the western North Pacific outgoing longwave radiation anomaly (WNP (OLR)). Using these, three new prediction models are developed. A simple arithmetic ensemble mean produces much improved forecast skills compared to the original prediction model of Lee and Seo (2013). Skill scores measured by temporal correlation and MSSS (mean square error skill score) are improved by about 9% and 17%, respectively. The GMSS (Gerrity skill score) and hit rate based on a tercile prediction validation scheme are also enhanced by about 19% and 13%, respectively. The reversed NIO, reversed WNP (OLR), and reversed NAC are all related to the enhancement of a cyclonic circulation anomaly to the south or southwest of the Korean peninsula, which induces southeasterly moisture flux into the peninsula and increasing Changma precipitation. The EUSC predictor induces an enhancement of the Okhotsk Sea high downstream and thus strengthening of Changma front. 相似文献
60.