• The Korean Journal of Malacology
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• v.27 no.4
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• pp.299-306
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• 2011

This paper examines relation between growth of adult top shell and their selectivity over different marine algae. For the study the top shell density and the algal species in different depth were surveyed by SCUBA. To test selectivity over different types of algae, five algal species including Ecklonia cava, Undaria pinnatifida, Ulva spp, Gelidium amansii and Sargassum spp were provided to top shells in indoor water tank condition. In the field survey, the wet weight of Ecklonia cava was significantly (r = 0.612, p < 0.05) correlated to the shell length (SL) of top shell. In the indoor water tank experiment conducted over 12 hours after sunrise, adult top shell (SL > SL 4.5 cm) tended to select Ecklonia cava and Undaria pinnatifida, which are common and abundant algal in the subtidal waters in Jeju Island. Our field survey and the indoor experiment suggest that E. cava and U. pinnatifida could be food preferred by adult top shell in its habitat.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.1
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• pp.1-6
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• 1971

In order to study the catching efficiency of shrimp trawl equipped with electrodes around the net mouth and stimulant devices attached to the ground rope, an experimental operation was carried out at Oma-Island Shrimp Farm from October 3rd to November 5th, 1970. Many studies have been made on the shrimp trawl with electric stimulant devices, but few can be found for detailed scientific catching methods. Electric power consumption was so excessive that electric stimulant devices could not be developed for commercial purposes. As a first step toward the successive operations of the electric stimulant devices in the field, it is necessary to study fundamental principles, such as electric current, voltage, electric potential, potential difference, electric field and suitable pulse. The behaviour response of the common shrimp, Penaeus japonicus BATE to moving nets and electric stimulant devices were reported in the preceding papers based on the water tank experiments (Ko and Kim, 1970). Through comparative fishing tests the rate of catching efficiency during daylight time was confirmed to be from 89 to 96 per cent of the night catch efficiency, and with 30 V. 1.5 A. electric power was sufficent for practical sea operation.

• Proceedings of the KSRS Conference
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• v.2
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• pp.969-972
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• 2006

The long-range High-Frequency (HF) ocean radar system has observed surface velocity field in the upstream of the Kuroshio north of Ishigaki Island and east of Taiwan since 2001. Applying a new method to extract geostrophic velocity component from the HF surface velocity data with the aid of satellite-born wind data, time series of daily surface geostrophic velocity field has been determined. Despite limited width of the study area of the HF radar, analysis of the sea surface height anomaly determined from the satellite altimetry data in a wider area can provide estimated dates of arrival of mesoscale eddies in the study area of the HF radar. Variations of the Kuroshio position and strength are studied in detail for these cases of interaction with mesoscale eddy, although number of occurrence of direct interaction with the Kuroshio in the study area is not statistically enough. For example, when an anticyclonic eddy approaches to the Kuroshio, the Kuroshio axis is found tend to move northward, keeping away from the approaching eddy from the east.

• Animal Systematics, Evolution and Diversity
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• v.21 no.1
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• pp.21-30
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• 2005

The morphogenesis of the marine ciliate, Pelagostrobilidium simile Song and Bradbury, 1998, was investigated using pyridine silver carbonate impregnation. The morphogenesis of P. simile is of hypoapokinetal mode. The oral primordium of P. simile commences slightly below the external membranelles (EM) with the proliferation of an anarchic field. Somatic ciliature in proter and opisthe of P. simile are derived from the old structure with the proliferation of the basal bodies during the dividing process. Parental oral apparatus of P. simile is inherited by the proter, and no reorganization of oral apparatus was observed in the parental oral infraciliature.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1046-1050
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• 2010

During construction of a sea-crossing bridge grouting was used to fill densely the space between the bottom of caisson and the ground. This grout mixture was mixed with an anti-washout admixture after locating accurately the pre-cast caisson on three concrete landing pads. This method differs significantly from the costly conventional method, for bridge foundations offshore, where concrete is placed in situ after excavating inside of a temporary concrete coffering wall. To verify the grouting method in advance, the full-scale field tests were performed twice on land. After identifying the fluidity of the grout material to be filled, finding some possible problems with the main construction and revising the original design, the main construction has been continuing successfully with 20 caissons completed to date. The purpose of this paper is to introduce for the first time in Korea the grouting method including the automatic and the manual monitoring system based on the main construction of the caisson foundation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.299-303
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• 2005

A new method of oil separation from oil-contaminated seawater based on electromagnetic forces, so-called MHD method was designed and formulated. MHD method has advantages of easy treatment of separated oil as well as little effect upon the environment, comparing with a conventional separation method using magnetic powders. Assuming high polymer particles instead of oil, the separation ratio (the mass of simulation particles / the total mass of simulation particles) for the sample fluid was calculated as fuction of electric current, magnetic field and seawater velocity.

• Atmosphere
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• v.23 no.4
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• pp.401-412
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• 2013

East Asia experienced extremely cold weather in January 2011, while the previous December and the following February had normal winter temperature. In this study National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data are used to investigate the characteristic features observed in the meteorological fields such as temperature, sea-level pressure, geopotential height, and wind during this winter period. In January the planetary-wave pattern is dominated by stationary-wave form in the mid-to-high latitude region, while transient waves are significant in the previous month. To understand the planetary-wave features quantitatively, harmonic analyses have been done for the 500-hPa geopotential height field. In the climatological-mean geopotential heights the wave numbers 1, 2, and 3 are dominant during the whole winter. In January 2011 the waves of number 1, 2, and 3 are dominant and stationary as in the climatological-mean field. In December 2010 and February 2011, however, the waves of number 4, 5, and 6 play a major role and show a transient pattern. In addition to the distinctive features in each month the planetary-wave patterns dependent on the latitude are also discussed.

• The Journal of the Acoustical Society of Korea
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• v.16 no.5
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• pp.60-67
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• 1997

the famous King Song-dok Bell which was cast in A.D. 771, during Silla dynasty has significant xize of concave cavity which acts as Helmholtz resonator on the ground. To see the effect of this cavity and the bell's internal acoustic cavity on radiating sound of bell, three dimensional measurement of internal sound field was performed. In this paper, the dtail measurement procedure and results are carefully addressed. The effect of the cavity on the radiating sound of bell is investigated using simple and physically representative model. A new size of cavity is proposed.

• Journal of the Korea Safety Management & Science
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• v.11 no.2
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• pp.95-101
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• 2009

The present study is to estimate the effect of wave height affecting at the front face of breakwater systems due to specification of submarine trench such as distance from breakwater to dredged area and width of dredge. The wave diffraction field, which is important hydraulic factor in the ocean, is considered to be two dimensional(2D) plane and the configuration of the submarine dredge on the sea bed designated by single horizontal long-rectangular pit system according to the various specific conditions of dredged locations. The numerical simulation is performed by using Green function based on the boundary integral equation and meshed at moving boundary conditions. The results of present numerical simulations are illustrated by applying the normal incidence. It is shown that the ratios of wave height at the front face of breakwater was varied by dependance of distant from breakwater to dredged area and width of dredge. It means that, when the navigation channel or pit breakwater is dredged on seabed, engineers have to consider the specification of dredge. This study can effectively be utilized for safety assessment to various breakwater systems in the ocean field and provided for safety construction of offshore structure.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.109-112
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• 2006

Successful field test results for high-current time-lapse electrical imaging in marine sediments area are discussed. Because field trial by commercially available equipments were failed, self-developed system which supports transmitting current up to 5 ampere was used. Some weak zones due to local fractures were detected, but the weak zone effect in this area by time-lapse measurements from sea level change was minor.