Influence on lateral rigidity of offshore piles using proposed p–y curves     

Sangseom Jeong  Youngho Kim  Jaeyoung Kim 《Ocean Engineering》2011,38(2-3):397-408

A fundamental study of pile–soil systems subjected to lateral loads in offshore deposit was conducted using experimental tests and numerical analysis. The emphasis was on the soil–pile rigidity of a laterally loaded pile in marine clay. Rigid- and flexible-pile analyses were conducted for comparison. A framework for determining the lateral load transfer curve (p–y curves) is proposed based on both field and laboratory model tests. A numerical analysis that takes into account the proposed p–y curves was performed for the pile flexibility parameters such as pile diameter, pile length, pile-bending stiffness, and the modulus of subgrade reaction. Based on the analysis, it is shown that the differences in bending moment and lateral displacement are more significant for flexible piles rather than rigid piles. It was found that the p–y curves influence the behavior of flexible piles more than rigid piles, thus the magnitude and distribution of the p–y curves are significantly important in flexible pile design.  相似文献   

Interactions between the pathogenic bacterium <Emphasis Type="Italic">Vibrio parahaemolyticus</Emphasis> and red-tide dinoflagellates     

Kyeong Ah Seong  Hae Jin Jeong 《Ocean Science Journal》2011,46(2):105-115

Vibrio parahaemolyticus is a common pathogenic bacterium in marine and estuarine waters. To investigate interactions between V. parahaemolyticus and co-occurring redtide dinoflagellates, we monitored the daily abundance of 5 common red tide dinoflagellates in laboratory culture; Amphidinium carterae, Cochlodinium ploykrikoides, Gymnodinium impudicum, Prorocentrum micans, and P. minimum. Additionally, we measured the ingestion rate of each dinoflagellate on V. parahaemolyticus as a function of prey concentration. Each of the dinoflagellates responded differently to the abundance of V. parahaemolyticus. The abundances of A. carterae and P. micans were not lowered by V. parahaemolyticus, whereas that of C. polykrikodes was lowered considerably. The harmful effect depended on bacterial concentration and incubation time. Most C. polykrikoides cells died after 1 hour incubation when the V. parahaemolyticus concentration was 1.4×10⁷ cells ml⁻¹, while cells died within 2 days of incubation when the bacterial concentration was 1.5×10⁶ cells ml⁻¹. With increasing V. parahaemolyticus concentration, ingestion rates of P. micans, P. minimum, and A. carterae on the prey increased, whereas that on C. polykrikoides decreased. The maximum or highest ingestion rates of P. micans, P. minimum, and A. carterae on V. parahaemolyticus were 55, 5, and 2 cells alga⁻¹ h⁻¹, respectively. The results of the present study suggest that V. parahaemolyticus can be both the killer and prey for some red tide dinoflagellates.  相似文献   

First report on the occurrence of the comb pen shell,Atrina pectinata (Linnaeus, 1767) (Bivalvia: Pinnidae) in Ulleungdo Island in the East Sea: Ecology and molecular identification of the species using COI gene sequence     

Hyun-Sung Yang  Hyun-Sil Kang  Heung-Sik Park  Choong Hwan Noh  Eui-Young Jeong  Kwang-Sik Choi 《Ocean Science Journal》2015,50(4):649-655

Pen shell is one of the largest marine bivalves inhabiting shallow subtidal soft bottoms in the west Pacific and Indian Oceans. In Korea, the comb pen shell Atrina pectinata fisheries has been established on the south and west coasts. Recently, a pen shell population has been discovered from a subtidal sand flat (25–30 m depth) in Ulleungdo Island located in the East Sea of Korea, suggesting a potential shellfish resource in this area. In the present study, we first surveyed the population density and size of the unique pen shell using SCUBA, and identified the pen shell to species level using mitochondrial cytochrome oxidase I gene (COI) sequence. An underwater survey carried out from July to September 2013 revealed that populations of pen shell patched on subtidal sand flat at a depth of 20–25 m. Grain size analysis indicated that sand particles accounted for 99% of the 600 × 700 m sand flat. The underwater survey also indicated that density of the pen shell ranged between 6–19 ind/m², with a mean of 11 ind/m². Shell height (i.e. longest axis of the shell) of the pen shell on the sand flat varied between 17.2 cm to 28.8 cm, with a mean of 25.1 cm, and the age was estimated to range between 1.5–7.5 yrs, with a mean of 5 yr. COI DNA sequence obtained from the pen shell in this study showed 98.9–99.2% similarity to Atrina pectinata (Linnaeus 1767) reported from Japan. In the cluster analysis, the COI DNA sequence of the pen shells from Ulleungdo Island was grouped with A. pectinata reported from Japan and China, indicating that the pen shell discovered in this study was A. pectinata, commonly distributed on the west and south coasts of Korea.  相似文献   

Effects of CO2-induced ocean acidification on the growth of the larval olive flounder Paralichthys olivaceus     

Kim  Kyung-Su  Shim  Jeong Hee  Kim  Suam 《Ocean Science Journal》2015,50(2):381-388

It widely thought that ocean acidification processes that caused by atmospheric CO₂ increase and accordingly lower seawater pH conditions might cause serious harm to marine food webs in certain ecosystems in the near future. Little is known about how marine fishes respond to reduced pH conditions. We investigated the effects of CO₂ conditions on the growth of olive flounder (Paralichthys olivaceus) larvae. Newly hatched larvae were reared at three different levels of pCO₂ (574, 988 and 1297 µatm) in temperature-controlled (21 ± 0.5°C) water tanks for four weeks until metamorphosis. The experiment was repeated three times in May, June, and July 2011, and body lengths and weights were measured at the completion of each experiment. The results indicated that the body length and weight of flounder larvae significantly increased with increasing CO₂ concentrations (P < 0.05). A higher daily growth rate during the early larval stage (hatching to 14 days) was found among the larvae reared in low pCO₂ conditions, while a significantly lower growth rate was found among larvae in higher pCO₂ water conditions. On the other hand, in the late larval stage (18 days after hatching to metamorphosis), the daily growth rate of larvae was much higher in high CO₂ water. Bone density of larvae, however, decreased with increasing CO₂ concentration in the water

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A Monte Carlo study of polarization structures in the Thomson-scattered line radiation     

Hyo Jeong Kim  Hee-Won Lee  Suna Kang 《Monthly notices of the Royal Astronomical Society》2007,374(1):187-195

Thomson scattering is often invoked to explain broad wing features that are seen in various objects including active galactic nuclei and symbiotic stars. Despite the wavelength-independent scattering cross-section of Thomson scattering, the line flux may exhibit wavelength-dependent linear degree of polarization, because various parts of emission wings are contributed by photons with different scattering numbers. Specifically, more scattered and hence more weakly polarized photons tend to fill the farther wing parts from the line centre, while the neighbourhood of the line centre is dominated by less-scattered photons with higher degree of polarization. Using a Monte Carlo technique, we investigate the polarization structure of Thomson-scattered line radiation. A detailed analysis of polarization structure formation is conducted by investigating the dependence of the polarization and profile width on the scattering number for various finite electron scattering slabs. Significantly varying degree of polarization is obtained when the scattering medium has Thomson optical depth  τ_Th≥ 1  . We present our high-resolution spectrum of the symbiotic star V1016 Cyg obtained with the Bohyunsan Optical Echelle Spectrograph (BOES) in order to fit the broad profile around Hα by electron scattering wings adopting an oblate spheroidal geometry with Thomson optical depth  τ_Th= 0.5  and electron temperature   T _e= 6.2 × 10⁴  K  . Local maxima in the linear degree of polarization of Thomson-scattered line radiation are expected to appear in the spectral regions characterized by the average scattering number ≃1.  相似文献   

Simulation of tunnel response under spatially varying ground motion     

Duhee Park  Myung Sagong  Dong-Yeop Kwak  Chang-Gyun Jeong 《Soil Dynamics and Earthquake Engineering》2009,29(11-12):1417-1424

Various components including wave scattering, wave passage, and site amplification effects cause the ground motion to vary spatially. The spatially varying ground motion can significantly influence the dynamic response of longitudinal structures such as bridges and tunnels. While its effect on bridges has been extensively studied, there is a lack of study on its effect on underground tunnels. This paper develops a new procedure for simulating the tunnel response under spatially varying ground motion. The procedure utilizes the longitudinal displacement profile, which is developed from spatially variable ground motion time histories. The longitudinal displacement profile is used to perform a series of pseudo-static three-dimensional finite-element analyses. Results of the analyses show that the spatially variable ground motion causes longitudinal bending of the tunnel and can induce substantial axial stress on the tunnel lining. The effect can be significant at boundaries at which the properties of the ground change in the longitudinal direction.  相似文献   

Role of Siliceous Fossil Dissolution in Downcore Variations of Grain Size and Water Content: Western Margin of Clarion-Clipperton Fracture Zone,NE Equatorial Pacific     

Hoi-Soo Jung  Kap-Sik Jeong  Yong-Shik Chu  Sung-Hyun Park  Ki-Hyune Kim 《Marine Georesources & Geotechnology》2013,31(3):181-195

Abstract

Grain size and water content in box-core sediments from the Clarion-Clipperton fracture zone (C-C zone) in the northeast equatorial Pacific were analyzed in detail to understand the downcore variations across a hiatus between Quaternary and Tertiary layers. Grain-size distributions in the topmost core sediments show two modes: a coarse mode (peaked at 50 μm) and a fine mode (at 2–25 μm). The coarse mode disappears gradually with depth accompanied by the dissolution of siliceous fossil tests, whereas the fine mode coarsens due to the formation of authigenic minerals. Water content increases abruptly across a color boundary between an upper pale brown layer and a lower dark brown layer that is the hiatus between Quaternary and Tertiary layers. Abundant smectites and microvoid molds, which are created by the prolonged fossil dissolution in the underlying sediment, are attributed for the abrupt downcore variation of water content. Overall variations in grain size and water content in the topmost core sediments in the western C-C zone are possibly constrained by the dissolution of biogenic siliceous fossils. Variations in geotechnical properties related to these changes must be considered in the design of nodule collectors.  相似文献   

Numerical analysis of passive pile groups in offshore soft deposits   总被引：1，自引：0，他引：1  

Sangseom Jeong  Donghee Seo  Youngho Kim   《Computers and Geotechnics》2009,36(7):1164-1175

The performance of pile foundations in offshore soft deposits is frequently dominated by passive loading from approach embankments for reclaimed land in Korea. This is mainly because of a Korean offshore soil profile, involving an over 30 m normally consolidated soil, with a strength that varies linearly with depth. This paper presents the results of an investigation on short- and long-term passive loading on the piles using two dimensional elastoplastic-consolidation coupled FEM analyses with large strain mode. This numerical scheme is essentially based on an updated Lagrangian formulation, which is favorably validated in cases of both centrifuge tests and field measurements. Although a parametric study is limited by some of the application, it is shown that passive pile loading is primarily affected by soil profile, pile head boundary condition, magnitude of embankment load, and average degree of consolidation. Simultaneously, time-dependent effect of shear transfer at the pile head is explicitly identified and a useful starting point in design is recommended for passive pile loading in construction (short-term) and consolidation (long-term) phases.  相似文献   

Load transfer analysis of rock-socketed drilled shafts by coupled soil resistance     

Hoonil Seol  Sangseom Jeong  Yongmin Kim 《Computers and Geotechnics》2009

The load distribution and deformation of rock-socketed drilled shafts subjected to axial loads are evaluated by a load transfer method. The emphasis is on quantifying the effect of coupled soil resistance in rock-socketed drilled shafts using 2D elasto-plastic finite element analysis. Slippage and shear-load transfer behavior at the pile–soil interface are investigated by using a user-subroutine interface model (FRIC). It is shown that the coupled soil resistance acts as pile-toe settlement as the shaft resistance is increased to its ultimate limit state. Based on the results obtained, the coupling effect is closely related to the ratio of the pile diameter to soil modulus (D/E_s) and the ratio of total shaft resistance against total applied load (R_s/Q). Through comparison with field case studies, the 2D numerical analysis reasonably estimated load transfer of pile and coupling effect, and thus represents a significant improvement in the prediction of load deflections of drilled shafts.  相似文献   

The SAURON project – XIII. SAURON–GALEX study of early-type galaxies: the ultraviolet colour–magnitude relations and Fundamental Planes     

Hyunjin Jeong  Sukyoung K. Yi  Martin Bureau  Roger L. Davies  Jesús Falcón-Barroso  Glenn van de Ven †  Reynier F. Peletier  Roland Bacon  Michele Cappellari  Tim de Zeeuw  Eric Emsellem  Davor Krajnovi&#;  Harald Kuntschner  Richard M. McDermid  Marc Sarzi  Remco C. E. van den Bosch 《Monthly notices of the Royal Astronomical Society》2009,398(4):2028-2048

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