Parameter estimations of a storm surge model using a genetic algorithm     

Sung Hyup You  Yong Hee Lee  Woo Jeong Lee 《Natural Hazards》2012,60(3):1157-1165

A genetic algorithm was used to optimize the parameters of the two-dimensional Storm Surge/Tide Operational Model (STORM) to improve sea level predictions of storm surges. The model was then tested using data from Typhoon Maemi, which landed on the Korean Peninsula in 2003. The following model parameters were used: the coefficients for bottom drag, background horizontal diffusivity, Smagorinsky’s horizontal viscosity, and sea level pressure scaling. The simulation results using the optimized parameters improved sea level predictions. This study demonstrates that parameter optimizations and their adequate applications are essential for improving model performance.  相似文献   

Material characteristics and deterioration evaluation for the 13th century Korean stone pagoda of Magoksa temple     

Young Hoon Jo  Chan Hee Lee  Yu Gun Chun 《Environmental Earth Sciences》2012,66(3):915-922

This study focused on the quantitative deterioration evaluation for the Magoksa temple stone pagoda of the thirteenth century in Korea, based on the deterioration map by precise observation and ultrasonic velocity measurements. The stone pagoda is composed mainly of fine-grained quartz diorite with some granodiorite used in the second story and dew bowl, and the replacement stone for restoration in the basement is biotite granite. The deterioration map and the 2D contour map projecting ultrasonic velocity showed that the most serious deterioration was to the north face of the pagoda, which has about 81.2% deterioration rate and a low velocity range compared with the other directions. Thus, it is required to prepare conservation schemes to reduce deterioration and reinforce the structure. It is also required to carry out ground exploitation for calculation of load carrying strength and ground strength together with continuous structural monitoring. The results will be important for the stable and long-term conservation of the pagoda and will further serve to establish scientific conservation systems of stone cultural heritages in the future.  相似文献   

Effects of ocean acidification driven by elevated CO<Subscript>2</Subscript> on larval shell growth and abnormal rates of the venerid clam, <Emphasis Type="Italic">Mactra veneriformis</Emphasis>     

Jee-Hoon Kim  Ok Hwan Yu  Eun Jin Yang  Sung-Ho Kang  Won Kim  Eun Jung Choy 《中国海洋湖沼学报》2016,34(6):1191-1198

The venerid clam (Mactra veneriformis Reeve 1854) is one of the main cultured bivalve species in intertidal and shallow subtidal ecosystems along the west coast of Korea. To understand the effects of ocean acidification on the early life stages of Korean clams, we investigated shell growth and abnormality rates and types in the D-shaped, umbonate veliger, and pediveliger stages of the venerid clam M. veneriformis during exposure to elevated seawater pCO₂. In particular, we examined abnormal types of larval shell morphology categorized as shell deformations, shell distortions, and shell fissures. Specimens were incubated in seawater equilibrated with bubbled CO₂-enriched air at (400±25)×10^-6 (ambient control), (800±25)×10^-6 (high pCO₂), or (1 200±28)×10^-6 (extremely high pCO₂), the atmospheric CO₂ concentrations predicted for the years 2014, 2084, and 2154 (70-year intervals; two human generations), respectively, in the Representative Concentration Pathway (RCP) 8.5 scenario. The mean shell lengths of larvae were significantly decreased in the high and extremely high pCO₂ groups compared with the ambient control groups. Furthermore, under high and extremely high pCO₂ conditions, the cultures exhibited significantly increased abundances of abnormal larvae and increased severity of abnormalities compared with the ambient control. In the umbonate veliger stage of the experimental larvae, the most common abnormalities were shell deformations, distortions, and fissures; on the other hand, convex hinges and mantle protuberances were absent. These results suggest that elevated CO₂ exerts an additional burden on the health of M. veneriformis larvae by impairing early development.  相似文献   

Semi-empirical Model for Estimating the Small-Strain Shear Modulus of Unsaturated Non-plastic Sandy Soils     

Won Taek Oh  Sai K. Vanapalli 《Geotechnical and Geological Engineering》2014,32(2):259-271

The shear modulus at small-strain, G _max is a maximum value of shear modulus for a given stress state and void ratio, and is a key parameter to evaluate the dynamic response of geotechnical structures. However, the laboratory testing procedures for determining G _max are time-consuming, cumbersome and require elaborate equipment especially for unsaturated soil samples. A semi-empirical model is proposed in this paper that can be used to estimate the variation of G _max with respect to matric suction for non-plastic sandy soils (i.e. I _p  = 0 %). The proposed model uses the Soil–Water Characteristic Curve (SWCC) and the shear modulus at saturation condition along with two fitting parameters ζ and ξ. The proposed model permits estimation of the variation of G _max with respect to matric suction over different zones of the SWCC (i.e. boundary effect, transition, and residual zones) for various non-plastic sandy soils. The fitting parameters ζ and ξ required for the proposed semi-empirical model can be estimated from simple relationships derived from the grain size distribution curve.  相似文献   

GNSS integration with vision-based navigation for low GNSS visibility conditions   总被引：1，自引：1，他引：0  

Dae Hee Won  Eunsung Lee  Moonbeom Heo  Sangkyung Sung  Jiyun Lee  Young Jae Lee 《GPS Solutions》2014,18(2):177-187

In urban canyons, buildings and other structures often block the line of sight of visible Global Navigation Satellite System (GNSS) satellites, which makes it difficult to obtain four or more satellites to provide a three-dimensional navigation solution. Previous studies on this operational environment have been conducted based on the assumption that GNSS is not available. However, a limited number of satellites can be used with other sensor measurements, although the number is insufficient to derive a navigation solution. The limited number of GNSS measurements can be integrated with vision-based navigation to correct navigation errors. We propose an integrated navigation system that improves the performance of vision-based navigation by integrating the limited GNSS measurements. An integrated model was designed to apply the GNSS range and range rate to vision-based navigation. The possibility of improved navigation performance was evaluated during an observability analysis based on available satellites. According to the observability analysis, each additional satellite decreased the number of unobservable states by one, while vision-based navigation always has three unobservable states. A computer simulation was conducted to verify the improvement in the navigation performance by analyzing the estimated position, which depended on the number of available satellites; additionally, an experimental test was conducted. The results showed that limited GNSS measurements can improve the positioning performance. Thus, our proposed method is expected to improve the positioning performance in urban canyons.  相似文献   

Distribution of small plastic debris in cross-section and high strandline on Heungnam beach, South Korea     

Nak Won Heo  Sang Hee Hong  Gi Myung Han  Sunwook Hong  Jongmyoung Lee  Young Kyung Song  Mi Jang  Won Joon Shim 《Ocean Science Journal》2013,48(2):225-233

The spatial distribution of small plastic debris on Heungnam beach in February 2011 was investigated. The abundances of small plastic debris over 2 mm in size along the high strandline and cross-sectional line of the beach were determined. The mean abundances of small plastics were 976 ± 405 particles/m² at the high strandline in the upper tidal zone along the shoreline and 473 ± 866 particles/m² at the cross-section perpendicular to the shoreline. Specifically, styrofoam (expanded polystyrene) spherules accounted for 90.7% of the total plastic abundance in the high strandline and 96.3% in the cross-section. The spatial distribution patterns of small plastic debris differed between the high strandline and cross-sectional line. The cross-sectional distribution of small plastic abundance differed among plastic types, indicating that representative sampling of small plastic debris on a beach is necessary.  相似文献   

Geophysical Surveys in the Jebel Hamrat Fidan,Jordan     

Alan J. Witten  Thomas E. Levy  Russell B. Adams  I.J. Won 《Geoarchaeology》2000,15(2):135-150

The Jebel (Jebel is mountain in Arabic) Hamrat Fidan marks the “gateway” to the Feinan district of southern Jordan—one of the largest sources of copper during the prehistoric and Early Bronze Ages in the eastern Mediterranean. Preliminary excavations and surveys at sites along the Wadi Fidan have revealed a long history of settled occupation extending from the Pre‐Pottery Neolithic (ca. 6,500 B.C.) to early medieval times. Because of this long history of occupation, and the fact that this area was a regional center for the production of copper, the study of this area is important for understanding early metallurgy, craft specialization, and social evolution. During the summer of 1997, geophysical investigations at a series of Neolithic and Bronze Age sites identified specific areas within Wadi Fidan for future intensive excavations. Three geophysical techniques (electromagnetic induction, ground‐penetrating radar, and magnetometry) were used to help locate buried architectural and industrial features remaining from early mining and metallurgical operations, including copper ore bodies or voids. Geophysics was not used at the actual mining sites because of scheduling constraints; however, geophysics did delineate buried stone walls at three distinct Wadi Fidan sites. Magnetometry and ground penetrating radar provided little useful information. Buried stone walls were apparently “masked” by numerous magnetic stones on the ground surface making magnetometry useless. Reflections from known strata demonstrated that radar penetrated the ground adequately; however, known shallowly buried walls were not recognizable. Electromagnetic induction produced maps of linear and rectilinear features that suggested spatial distribution of widespread buried stone walls suitable for future excavation. A significant and unexpected finding was that electromagnetic induction proved capable of delineating buried stone walls. © 2000 John Wiley & Sons, Inc.  相似文献