Development of the AUV ‘ISiMI’ and a free running test in an Ocean Engineering Basin     

Bong-Huan Jun  Jin-Yeong Park  Pan-Mook Lee  Kihun Kim  Jun-Ho Oh 《Ocean Engineering》2009,36(1):2-14

The Korea Ocean Research and Development Institute (KORDI) has developed a small AUV named ISiMI. The mission of ISiMI is to work as a test-bed AUV for the development and validation of various algorithms and instruments required to enhance the AUV's functions. The design concept of ISiMI is that of a vehicle small enough to cruise the Ocean Engineering Basin (OEB) of KORDI and to be handled by one or two people. The downsized design and the cruising ability in its tank enable fast experimental feedback on AUV technologies and a shorter development period for new technologies. This paper presents a review of our research work on the development of ISiMI, with a performance evaluation by simulation and an experimental test. After the design and implementation of ISiMI, including its positioning system in the OEB, are presented, a series of test results in the OEB and discussions of the results are presented, with comparisons of the simulation and experimental outputs.  相似文献   

Dissolved organic phosphorus utilization and alkaline phosphatase activity of the dinoflagellate <Emphasis Type="Italic">Gymnodinium impudicum</Emphasis> isolated from the South Sea of Korea     

Seok Jin Oh  Hyeong Kyu Kwon  Il Hyeon Noh  Han-Soeb Yang 《Ocean Science Journal》2010,45(3):171-178

This study investigated alkaline phosphatase (APase) activity and dissolved organic and inorganic phosphorus utilization by the harmful dinoflagellate Gymnodinium impudicum (Fraga et Bravo) Hansen et Moestrup isolated from the South Sea of Korea. Under conditions of limited phosphorus, observation of growth kinetics in batch culture yielded a maximum growth rate (μ_max) of 0.41 /day and a half saturation constant (Ks) of 0.71 μM. In time-course experiments, APase was induced as dissolved inorganic phosphorus (DIP) concentrations fell below 0.83 μM, a threshold near the estimated Ks; APase activity increased with further DIP depletion to a maximum of 0.70 pmol/cell/h in the senescent phase. Thus, Ks may be an important index of the threshold DIP concentration for APase induction. G. impudicum utilizes a wide variety of dissolved organic phosphorus compounds in addition to DIP. These results suggest that DIP limitation in the Southern Sea of Korea may have led to the spread of G. impudicum along with the harmful dinoflagellate Cochlodinium polykrikoides in recent years.  相似文献   

Vertical structure of the M<Subscript>2</Subscript> tidal current in the Yellow Sea   总被引：2，自引：0，他引：2  

Seok Lee  Heung-Jae Lie  Cheol-Ho Cho  Sok Kuh Kang  William J. Teague  Kyung-Il Chang  Kyu-Min Song  Kyung-Hee Oh 《Ocean Science Journal》2011,46(2):73-84

The vertical structure of the M₂ tidal current in the Yellow Sea is analyzed from data acquired using an acoustic Doppler current profiler. The observed vertical profiles of the M₂ tidal current are decomposed into two rotating components of counter-clockwise and clockwise, and restructured using a simple one-point model with a constant vertical eddy viscosity. The analyzed results show that the internal fictional effect dominates the vertical structure of the tidal current in the bottom boundary layer. In the Yellow Sea, the effect of the bottom friction reduces the current speed by about 20–40% and induces the bottom phase advance by about 15–50 minutes. In the shallower coastal regions, the effects of bottom topography are more prominent on the vertical structure of tidal currents. The vertical profile of the tidal current in summer, when the water column is strongly stratified, is disturbed near the pycnocline layer. The stratification significantly influences the vertical shear and distinct seasonal variation of the tidal current.  相似文献   

A preliminary report of persistent organochlorine pollutants in the Yellow Sea   总被引：5，自引：0，他引：5  

Oh JR  Choi HK  Hong SH  Yim UH  Shim WJ  Kannan N 《Marine pollution bulletin》2005,50(2):217-222

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Tectonic evolution of Korean Peninsula and adjacent crustal fragments in Asia: Introduction     

Chang Whan Oh  K. Sajeev  Sung Won Kim  M. Santosh 《Gondwana Research》2006,9(1-2):19

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Effects of surfactants and electrolyte solutions on the properties of soil     

Junboum Park  Cumaraswamy Vipulanandan  Jee Woong Kim  Myoung Hak Oh 《Environmental Geology》2006,49(7):977-989

Biosurfactants are frequently used in petroleum hydrocarbon and dense non-aqueous phase liquids (DNAPLs) remediation. The applicability of biosurfactant use in clayey soils requires an understanding and characterization of their interaction. Comprehensive effects of surfactants and electrolyte solutions on kaolinite clay soil were investigated for index properties, compaction, strength characteristics, hydraulic conductivities, and adsorption characteristics. Sodium dodecyl sulfate (SDS) and NaPO₃ decreased the liquid limit and plasticity index of the test soil. Maximum dry unit weights were increased and optimum moisture contents were decreased as SDS and biosurfactant were added for the compaction tests for mixtures of 30% kaolinite and 70% sand. The addition of non-ionic surfactant, biosurfactant, and CaCl₂ increased the initial elastic modulus and undrained shear strength of the kaolinite–sand mixture soils. Hydraulic conductivities were measured by fixed-wall double-ring permeameters. Results showed that the hydraulic conductivity was not significantly affected, but slightly decreased from 1×10⁻⁷ cm/s (water) to 0.3×10⁻⁷ cm/s for Triton X-100 and SDS. The adsorption characteristics of the chemicals onto kaolinite were also investigated by developing isotherm curves. SDS adsorbed onto soil particles with the strongest bonding strength of the fluids tested. Correlations among parameters were developed for surfactants, electrolyte solutions, and clayey soils.  相似文献   

Large seasonal changes in the recharge of seawater in a subterranean estuary revealed by a radon tracer          下载免费PDF全文

Yong Hwa Oh  Guebuem Kim 《水文研究》2016,30(14):2525-2532

Activities of radon (²²²Rn) in groundwater were continuously monitored in a saline aquifer from September 2010 to July 2011. The activities of ²²²Rn ranged from 200 to 4300 Bq m^?3, with a large seasonal variation. Because the activity of ²²²Rn in seawater is low, ²²²Rn in saline groundwater must be produced in the aquifer from radium (²²⁶Ra) in rocks and sediments. The ²²²Rn activities were higher in the warm‐dry seasons (September–November 2010 and April–May 2011) when the saline aquifer was stable. In contrast, the lowest ²²²Rn activities were observed in the cold‐dry season (December 2010 and January–March 2011), because of the effective exchange between groundwater and seawater. In addition, sudden decreases of ²²²Rn activities coincided with episodic drops in groundwater temperatures. These results reveal that lower seawater temperature in winter may result in density‐driven seawater intrusion. During the wet season (June–July 2011), ²²²Rn activities were more clearly affected by semi‐monthly and diurnal tidal pumping, showing higher ²²²Rn activities during low and spring tides. Such a tidal effect was not clearly observed during the warm‐dry and cold‐dry seasons. This result implies that the residence time of SGD in coastal zones is significantly affected by seasonal changes in driving forces such as tidal pumping and seawater intrusion. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

An analysis on movement patterns between zones using smart card data in subway networks     

Kwanho Kim  Kyuhyup Oh  Yeong Kyu Lee  SungHo Kim 《International journal of geographical information science》2014,28(9):1781-1801

Identifying zones and movement patterns of people is crucial to understanding adjacent regions and the relationship in urban areas. Most previous studies addressed zones or movement patterns separately without analysing simultaneously the two issues. In this article, we propose an integrated approach to discover directly both zones and movement patterns among the zones, referred to as movement patterns between zones (MZPs), from historical boarding behaviours of passengers in subway networks by using an agglomerative clustering method. In addition, evaluation measures of MZPs are suggested in terms of coverage and accuracy. The effectiveness of the proposed approach is finally demonstrated through a real-world data set obtained from smart cards on a subway network in Seoul, Korea.  相似文献   

Biomass and carbon storage of Gracilariopsis lemaneiformis （Rhodophyta） in Zhanshan Bay,Qingdao, China     

周伟  隋正红  王津果  胡依依  康庆浩  吴俊映  金相澈  黄建辉  王朋云 《中国海洋湖沼学报》2014,32(5):1009-1015

Marine macroalgae can absorb carbon and play an important role in carbon sequestration. As an important economic macroalga, Gracilariopsis lemaneiformis has the potential to significantly affect carbon absorption and storage in wave-sheltered intertidal reef systems. However, detailed knowledge on seasonal biomass changes and carbon storage of G. lemaneiformis is lacking, especially in many small and scattered ecosystems. Considering the influence of human activities on wild distribution of G. lemaneiformis, the understanding of seasonal dynamics of an economically important species in nature is necessary. In this study, we first investigated seasonal variations in biomass, coverage area, and carbon storage during low tide from August 2011 to July 2012 in Zhanshan Bay, Qingdao, China. Furthermore, we estimated the carbon storage potential of wild G. lemaneiformis using light use efficiency(LUE). The results show that the standing biomass and coverage area changed significantly with season. However, seasonal variations in carbon content and water content were not obvious, with an average content of 35.1% and 83.64%, respectively. Moreover, carbon storage in individual months varied between 0.67 and 47.03 g C/m 2, and the value of carbon storage was the highest in August and June and the lowest in February. In Zhanshan Bay, LUE of G. lemaneiformis was only 0.23%. If it is increased to the theoretical maximum(5%–6%), the carbon storage will have an increase of at least 21 times compared with the current, which suggested that carbon storage of wild G. lemaneiformis had a high enhancement potential. The study will help to assess a potential role of G. lemaneiformis in reducing atmospheric CO2.  相似文献   

Macrobenthos habitat mapping in a tidal flat using remotely sensed data and a GIS-based probabilistic model     

Choi JK  Oh HJ  Koo BJ  Lee S  Ryu JH 《Marine pollution bulletin》2011,62(3):564-572

This paper proposes and tests a method of producing macrofauna habitat potential maps based on a weights-of-evidence model (a probabilistic approach) for the Hwangdo tidal flat, Korea. Samples of macrobenthos were collected during field work, and we considered five mollusca species for habitat mapping. A weights-of-evidence model was used to calculate the relative weights of 10 control factors that affect the macrobenthos habitat. The control factors were compiled as a spatial database from remotely sensed data combined with GIS analysis. The relative weight of each factor was integrated as a species potential index (SPI), which produced habitat potential maps. The maps were compared with the surveyed habitat locations, revealing a strong correlation between the potential maps and species locations. The combination of a GIS-based weights-of-evidence model and remote sensing techniques is an effective method in determining areas of macrobenthos habitat potential in a tidal flat setting.  相似文献