Reproductive pattern of the epifaunal amphipodPontogeneia rostrata (Crustacea) on dolsando sandy shore in Korea     

Ok Hwan Yu  Seung Jin Jeong  Hae-Lip Suh 《Ocean Science Journal》2008,43(3):127-133

Reproductive patterns of an epifaunal amphipod,Pontogeneia rostrata, were studied on Dolsando sandy shore in Korea. The life history pattern was iteroparous, with recruitment mainly occurring from winter to spring. The sex ratio was male-biased, especially during breeding periods. The mean body length of females was significantly larger than that of males. Brood size and egg volume were positively related to the body length of ovigerous females. There was no significant difference in brood size between successive breeding periods, but egg volumes were significantly higher in early winter (December) than in late spring breeding (May and June), increasing the probability of survival to hatching. These traits contribute to more reproductive potential in early winter than in late spring breeding. The mean brood size of epifaunalP. rostrata was larger but the mean egg volume smaller than that of infaunal amphipods in this sampling area. We suggest that reproductive effort for epifaunal species may be proportionally greater than for infaunal species in risky environments.  相似文献   

Real-time acceleration monitoring-based rapid earthquake response for ports in Korea     

Chang-Guk Sun  Hyung-Ik Cho  Byung-Sun Jeong 《Marine Georesources & Geotechnology》2018,36(5):564-578

To establish viable earthquake counterplans for ports in Korea, data regarding earthquake motion on the ground and in buildings must be collected using acceleration monitoring systems. Acceleration monitoring-based strategies for port facilities are useful not only for ensuring rapid responses during and after earthquakes but also for regional data collection to assist reliable seismic design. Acceleration monitoring systems were installed at coastal facility sites in target ports, including a soil site to represent the facility and a rock site as a reference. The systematic earthquake alert software was designed to help them in decision-making about a possible seismic hazard and its reporting. The earthquake alert system was composed of two sequential functional software systems sharing an acceleration monitoring database applied to the target ports. The earthquake response software system triggers an alarm based on the peak ground acceleration per second computed from the monitored data. Then, the earthquake hazard estimation software system evaluates possible earthquake-induced site-specific geotechnical hazards linked to the peak ground acceleration. The integrated system was successfully operated and was able to rapidly provide an emergency report containing event records and geotechnical earthquake hazards during the September 2016 Gyeongju earthquake, the largest recorded earthquake in Korea.  相似文献   

A numerical study on deblending of land simultaneous shooting acquisition data via rank-reduction filtering and signal enhancement applications     

Woodon Jeong  Constantinos Tsingas  Mohammed S. Almubarak 《Geophysical Prospecting》2020,68(6):1742-1757

We propose a workflow of deblending methodology comprised of rank-reduction filtering followed by a signal enhancing process. This methodology can be used to preserve coherent subsurface reflections and at the same time to remove incoherent and interference noise. In pseudo-deblended data, the blending noise exhibits coherent events, whereas in any other data domain (i.e. common receiver, common midpoint and common offset), it appears incoherent and is regarded as an outlier. In order to perform signal deblending, a robust implementation of rank-reduction filtering is employed to eliminate the blending noise and is referred to as a joint sparse and low-rank approximation. Deblending via rank-reduction filtering gives a reasonable result with a sufficient signal-to-noise ratio. However, for land data acquired using unconstrained simultaneous shooting, rank-reduction–based deblending applications alone do not completely attenuate the interference noise. A considerable amount of signal leakage is observed in the residual component, which can affect further data processing and analyses. In this study, we propose a deblending workflow via a rank-reduction filter followed by post-processing steps comprising a nonlinear masking filter and a local orthogonalization weight application. Although each application shows a few footprints of leaked signal energy, the proposed combined workflow restores the signal energy from the residual component achieving significantly signal-to-noise ratio enhancement. These hierarchical schemes are applied on land simultaneous shooting acquisition data sets and produced cleaner and reliable deblended data ready for further data processing.  相似文献   

YSDP102钻孔有孔虫动物群与南黄海东南部古水文重建   总被引：8，自引：0，他引：8  

李铁刚  李绍全  苍树溪  刘健  Jeong Hae Chang 《海洋与湖沼》2000,31(6):588-595

所研究的YSDP1 0 2钻孔岩心 (33°49.496′N ,1 2 5°45.0 0 9′E)是由韩国能源研究所和中国国土资源部海洋地质研究所于 1 995年 8月联合取自南黄海东南部水深 62m的巨厚泥质沉积区内 ,岩心长 60 65m。通过对岩心沉积物中浮游和底栖有孔虫动物群的分析 ,结合相应的AMS1 4 C测年数据 ,对黄海暖流及与其相伴生的南黄海东南部冷水体的形成及演化进行了初步的探讨。结果表明 ,黄海暖流及与其相伴生的南黄海东南部冷水体形成于距今约640 0日历年前。形成伊始 ,冷水体处于明显的强势状态 ,而暖流的强度却相对较弱 ,这一过程约持续了 2 2 0 0年左右 ,是南黄海东南部巨厚泥质沉积区的主要堆积期。直到距今 42 0 0日历年前后 ,黄海暖流的影响强度开始加强 ,冷水体相对减弱 ,直至达到现代的水文状态。  相似文献   

A seismic survey to detect natural gas hydrate in the East Sea of Korea     

Jeong?Hwan?LeeEmail author  Young?Soon?Baek  Byong?Jae?Ryu  Michael?Riedel  Roy?D.?Hyndman 《Marine Geophysical Researches》2005,26(1):51-59

Recently, several countries have conducted projects to explore and develop natural gas hydrate, which is one of the new alternative energy resources for the future. In Korea, a five-year national research project was initiated in 2000. As part of this project, a seismic survey was performed in the East Sea of Korea to quantify the potential magnitude and distribution of natural gas hydrates. Multi-channel seismic data and core samples have been acquired and recovered in the survey area. Analysis of seismic data show clear bottom simulating reflectors (BSRs), seismic blank zones (or wipe-out zones) with velocity pull-up structure, and pock-marks. In this study, we present the results of seismic surveys which indicate the existence of natural gas hydrates in Korean offshore areas. These results will be applied to select areas for coring (or drilling) and detailed exploration such as 2D seismic survey with long offset or 3D seismic in the future.  相似文献   

Spatial and temporal aspects of phytoplankton blooms in complex ecosystems off the korean coast from satellite ocean color observations     

Yu -Hwan Ahn  Palanisamy Shanmugam  Kyung- Il Chang  Jeong -Eon Moon  Joo -Hyung Ryu 《Ocean Science Journal》2005,40(2):67-71

Complex physical, chemical and biological interactions off the Korean coast created several striking patterns in the phytoplankton blooms, which became conspicuous during the measurements of ocean color from space. This study concentrated on analyzing the spatial and temporal aspects of phytoplankton chlorophyll variability in these areas using an integrated dataset from a Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Advanced Very High Resolution (AVHRR) sensor, and Conductivity Temperature Depth (CTD) sensor. The results showed that chlorophyll concentrations were elevated in coastal and open ocean regions, with strong summer and fall blooms, which appeared to spread out in most of the enclosed bays and neighboring waters due to certain oceanographic processes. The chlorophyll concentration was observed to range between 3 and 54 mg m^-3 inside Jin-hae Bay and adjacent coastal bays and 0.5 and 8 mg m^-3 in the southeast sea offshore waters, this gradual decrease towards oceanic waters suggested physical transports of phytoplankton blooms from the shallow shelves to slope waters through the influence of the Tsushima Warm Current (TWC) along the Tsushima Strait. Horizontal distribution of potential temperature (θ) and salinity (S) of water off the southeastern coast exhibited cold and low saline surface water (θ<19°C; S<32.4) and warm and high saline subsurface water (θ>12°C; S>34.4) at 75dBar, corroborating TWC intrusion along the Tsushima Strait. An eastward branch of this current was called the East Korean Warm Current (EKWC), tracked with the help of CTD data and satellite-derived sea surface temperature, which often influenced the dynamics of mesoscale anticyclonic eddy fields off the Korean east coast during the summer season. The process of such mesoscale anticyclonic eddy features might have produced interior upwelling that could have shoaled and steepened the nutricline, enhancing phytoplankton population by advection or diffusion of nutrients in the vicinity of Ulleungdo in the East Sea.  相似文献   

Distribution and Acoustic Characteristics of Shallow Gas in the Korea Strait Shelf Mud off SE Korea     

Dae Choul Kim  Gwang Hoon Lee  Young Kyo Seo  Gil Young Kim  Seok Yun Kim  Jeong Chang Kim  Soo Chul Park  Roy Wilkens 《Marine Georesources & Geotechnology》2004,22(1):21-31

Shallow gas in the Korea Strait shelf mud (KSSM) off SE Korea, revealed by high-resolution subbottom profiles, is associated with acoustic blanking, acoustic turbidity, seepages with plumes in the water column, and seafloor depressions. The acoustic blanking, characterized by strong, consistent top reflection and wipeout below, is most dominant. The seaward edge of the acoustic blanking zone generally coincides with the 100-m water-depth contour, suggesting that the water depth (the pressure) may control the distribution of shallow gas. The acoustic turbidity, characterized by diffuse top reflection, is a dark smear, partially blanking the data below. The seepages with plumes, characterized by vertical smearing and disturbed seafloor, are seen only along the shallowest, landward edge of the acoustic blanking zone. This may suggest that the decreased gas solubility at shallow water depths, caused by the lowered pressure, increases the volume of free gas in the sediments, facilitating the gas escape. The seafloor depressions, interpreted as pockmarks, are accompanied by cone-shaped acoustic masking, which is probably the reflection from a narrow vent of gas. The gas-related acoustic anomalies appear to occur mostly in the upper, recent mud of the KSSM. Neither permeable beds nor faults, which can act as vertical migration pathways for deep thermogenic gas, are evident in the recent mud. We interpret that the bacterial degradation of organic matter in situ is the main source for the gas in the KSSM. The upwelling off SE Korea may be an important source for the increased organic matter in the area.  相似文献   

Weathering damage evaluation of rock properties in the Bunhwangsa temple stone pagoda,Gyeongju, Republic of Korea     

Chan Hee Lee  Jeong Eun Yi 《Environmental Geology》2007,52(6):1193-1205

The stone pagoda of the Bunhwangsa temple in Republic of Korea was made of piling small brick-shaped stones. The majority of stone bricks are andesitic rocks with variable geneses. Rock properties of the pagoda roof suffer partial significant deterioration, such as multiple peel-offs, exfoliation, onion-peel-like decomposition, cracks forming round lines and falling-off stone pieces. The stylobates and tabernacles at the four corners are composed of granitic rocks, which are heavily contaminated by lichens and mosses. Some of these contamination marks show dark black or yellowish brown colors by inorganic secondary hydrates. The four tabernacles and northern face of the pagoda body have been exposed to relatively high humidity, which causes light gray efflorescence as stalactites between the northern and western sides of the body. The efflorescences are composed of calcite, gypsum and clay minerals. The stone lion statues at the southeast and northeast corners are made of alkali granite, while the others are lithic tuff. Total rock properties of the pagoda consist of 9,708 stone bricks. Among them, 11.0% are fractured, 6.7% are fallen off, and 7.0% show considerable surface efflorescence, which shows that the pagoda has been highly deteriorated by physical, chemical and biological weathering. The authors strongly suggest long-term monitoring and comprehensive conservation researches.  相似文献   

Abrupt light changes and multiperiodicity in Be stars: EW Lacertae revisited     

K. Pavlovski  Ž. RuŽić  M. Pavlović  J. H. Jeong  I. -S. NHA 《Astrophysics and Space Science》1993,200(2):201-210

The combined 1983 campaign and Seoul data on the variable Be star EW Lac is reanalyzed. CLEANing of the Fourier transform of the present time series clearly shows more than a single period. A multiperiodic fit can account also for a sudden brightness change through frequency beating. Comparison with previous multiperiodic solutions based on data obtained in different seasons shows highly variable amplitudes of the pulsational frequencies. The consequence of this finding to variable shell activity of EW Lac is briefly pointed out.Yonsei University Observatory Contribution No. 98.  相似文献   

Full Waveform Inversion Using Student’s t Distribution: a Numerical Study for Elastic Waveform Inversion and Simultaneous-Source Method   总被引：1，自引：0，他引：1  

Woodon Jeong  Minji Kang  Shinwoong Kim  Dong-Joo Min  Won-Ki Kim 《Pure and Applied Geophysics》2015,172(6):1491-1509

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