• Animal Systematics, Evolution and Diversity
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• v.28 no.3
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• pp.192-207
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• 2012

To supply the morphological and ecological information of oligotrich ciliates in Korea, water samples were seasonally collected in Gwangyang Bay and Jinhae Bay from August, 2010 to February, 2012 and processed by quantitative protargol staining method. As a result, six species belonging to the genus Strombidium Clapar$\grave{e}$de and Lachmann, 1859 are identified: Strombidium emergens Kahl, 1932; S. dalum Lynn et al., 1988; S. epidemum Lynn et al., 1988; S. tressum Lynn et al., 1988; S. bilobum Lynn and Gilron, 1993; S. pollostomum Lynn and Gilron, 1993. These six species were newly reported from Korean coastal waters. Strombidium emergens is a middle sized Strombidium ($20-50{\mu}m$ in length) and has open and deep oral groove to girdle portion. Strombidium dalum is a small sized Strombidium (${\geq}20{\mu}m$ in length), that has torch-like spiral anterior membranelles and an inverted triangles-shaped macronucleus on the posterior pole. The small sized S. epidemum has conspicuous trichites surrounding the girdle portion and ventral membranelles distinctly separated from anterior membranelles. The small sized S. tressum has torch-like spiral and extremely long trichites among the cilia of anterior membranelles. The middle sized S. bilobum has a bilobed macronucleus. Strombidium pollostomum is also a small sized Strombidium but its ventral membranelles are continuously connected with anterior membranelles. The five species except S. emergens occurred frequently over the wide range of water temperatures and salinities.

• Korean Journal of Ichthyology
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• v.27 no.3
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• pp.233-237
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• 2015

Fish assemblages in the coastal waters off Gampo in the East Sea of Korea were analyzed using the samples of fishes collected with pot nets June, September, and December 2005 and March 2006. During the study period, a total of 19 fish species representing 10 families in 4 orders were collected. The fish assemblages predominantly consisted of Conger myriaster, which accounted for 38.9% of the number of individuals and 52.2% in the biomass. The next major specimens were Takifugu niphobles, Sebastes schlegelii, Chaenogobius annularis, Hexagrammos agrammus and Hexagrammos otakii. These five fishes accounted 44.1% of total number of individuals and 37.3% of total biomass. The number of fish species was the highest in March 2006 and the lowest in December 2005. The number of individuals and biomass were the highest in September in 2005 and the lowest in December in 2005.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.427-429
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• 2013

DGPS Reference Station the national infrastructure generates the DGPS correction information for Differential GPS. Currently, South Korea operates the software based DGPS reference station using the next generation DGPS architecture in order that upgrade the hardware based DGPS reference station. However the software based DGPS reference station proposed by USCG has not changed just a form of its structure but intimate architecture. Accordingly, It can't strengthen the advantages of software based architecture. In this paper, I will propose a new software architecture design that is integrated with DGPS reference station and integrity monitor. This architecture is more simple than existing one so can use the maritime DGPS reference station which is required more simple structure.

• Ocean and Polar Research
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• v.34 no.3
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• pp.325-335
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• 2012

It is well known that sound waves in the sea propagates under the influence of sea surface and bottom roughness, the sound speed profile, the water depth, and the density of sea floor sediment. In particular, an abrupt change of sound speed with depth can greatly affect sound propagation through an eddy. Eddies are frequently generated in the East Sea near the Korean Peninsula. A warm eddy with diameter of about 150 km is often observed, and the sound speed profile is greatly changed within about 400 m of water depth at the center by the eddy around the Ulleung Basin in the East Sea. The characteristics of low-frequency sound propagation across a warm eddy are investigated by a sound propagation model in order to understand the influence of warm eddies. The acoustic rays and propagation losses are calculated by a range-dependent acoustic model in conditions where the eddy is both present and absent. We found that low-frequency sound propagation is affected by the warm eddy, and that the phenomena dominate the upper ocean within 800 m of water depth. The propagation losses of a 100 Hz frequency are variable within ${\pm}15$ dB with depth and range by the warm eddy. Such variations are more pronounced at the deep source near the sound channel axis than the shallow source. Furthermore, low-frequency sound propagation from the eddy center to the eddy edge is more affected by the warm eddy than sound propagation from the eddy edge to the eddy center.

• Ocean and Polar Research
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• v.39 no.2
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• pp.125-148
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• 2017

This study analyzed the community structure of macrobenthic organisms in the subtidal area suffering under the influence of thermal discharge from the Uljin nuclear power plant during 2012-2013 and reviewed the temporal change in the faunal composition of the macrobenthic community using data from previous studies since the start of the plant operation in 1989. A total of 319 species were collected in 2012-2013, with a mean density of $3,330ind./m^2$ and a mean biomass of $131.96g/m^2$. These results were similar to those obtained in 2006-2007. The dominant species were not different from each other before and after the power plant operations began, but the faunal density near the power plant drainage port was significantly higher compared to those densities obtained from other stations. Spiophanes bombyx and Polydora sp., which is known as a pollution indicator species, was dominant only in the drainage port area. The study area consisted of two subregions with different macrobenthic communities depending on the water depth, which was similar to the results of the 2006-2007 survey. The macrobenthic community structures before and after the operation of the power plant in the coastal area were not changed, but there were seasonal differences in the long-term macrobenthic community structure which were strongly related to the thermal discharge from the power plant.

• Journal of the Korean GEO-environmental Society
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• v.17 no.8
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• pp.29-37
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• 2016

In order to prevent leakage of contaminants in offshore landfill, vertical barrier should be installed. Vertical barrier should be installed at designed depth of seabed to prevent the horizontal transport of contaminant in the subsurface. In this study, the seepage and contaminant transport in the subsurface according to embedded depth of vertical barrier were analyzed by using 2-D finite element analysis program SEEP/W and 3-D finite difference analysis program Visual Modflow. Numerical modelling results show that seepage flux and contaminant transport in seabed was greatly reduced when vertical barrier was installed at certain depth of low permeable layer. Therefore, the determination of minimum embedded depth for preventing contaminant leakage is helpful to design the economical vertical barrier.

• Journal of Ocean Engineering and Technology
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• v.26 no.6
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• pp.7-13
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• 2012

This paper presents a numerical study of the wave loads acting on offshore structures using a Cartesian-grid-based flow simulation method. Finite volume discretization with a volume-of-fluid (VOF) method is adopted to solve two-phase Navier-Stokes equations. Among the many variations of the VOF method, the CICSAM scheme is applied. The body boundary conditions are satisfied using a porosity function, and wave generation is carried out by using transient (wave or damping) zone approaches. In order to validate the present numerical method, three different basic offshore structures, including a sphere, Pinkster barge, and Wigley model, are numerically investigated. First, diffraction and radiation problems are solved using the present numerical method. The wave exciting and drift forces from the diffraction problems are compared with potential-based solutions. The added mass and wave damping forces from the radiation problems are also compared with the potential results. Next, the wave-induced motion responses of the structures are calculated and compared with the existing experimental data. The comparison results are fairly good, showing the validity of the present numerical method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.73-74
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• 2015

In the world the interests about a unmanned surface vehicle(USV) are growing up. However it is difficult to launch and recover a USV because of no men on board of USV. And it is more difficult in recovery than launch of USV. So in this research the heaving line launcher was developed to support the recovery of USV easier. And a mock-up was manufactured to validate for adoption to the USV. The muck-up is composed of launcher pipe, remote trigger, air tank, tow shell and heaving line. Tests in land using the mock-up were carried out. The forces by the heaving line launcher to USV were measured by a measuring table during the tests in land. In this paper the development of a mock-up of heaving line launcher, tests in land and the measured forces during tests are presented.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.448-457
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• 2013

Zooplankton community in the major ports of Korea, which were characterized by a specific marine environmental condition during summer, was studied. Water temperature in the ports of western areas was higher and while those in the East Sea was lower. Contradictorily, the salinity was lowest in the western areas, while being highest in the eastern area. The Chl-a concentration was highest in the southern areas and lowest in the eastern one. Zooplankton taxa were most diverse in the western areas and simplest in the eastern one. Copepods predominantly occurred in the western areas, but their abundance relatively decreased in the southern and eastern areas. Cluster analysis revealed that copepod communities were classified into 3 summit groups, the western, southern and eastern areas. The results indicate that zooplankton communities in Korean ports may be affected by biological factors like Chl-a concentration in addition to environmental factor such as temperature and salinity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.282-288
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• 2014

The DGPS reference station is a national infrastructure generating GPS correctional information and transmitting the signal for Differential GPS. Currently, Korea has applied and operated the software-based DGPS reference station as a standard of the next generation proposed by the USCG in order to improve the hardware-based DGPS reference system. However, software-based DGPS reference station proposed by USCG was changed in software method, only for form. There is no advantage to changing software-based because the most critical part of architecture has not been improved. In this paper, we have designed a new software-based marine DGPS station architecture that a reference station software and a monitor station were integrated. The new marine DGPS station architecture based on software is a more simplified structure than it used to be and can be utilized in the DGPS reference station.