• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.614-623
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• 2015

This study aims to estimate the Green-House-Gas emissions from domestic farmed flounder in the southern sea and Jeju-Do, where is mainly produced, by the assessment of energy consumptions and GHG emissions from domestic fish farms for establishing reduce standards of greenhouse gas from a sustainable perspective. It needs to analyze such GHG emission components as feed, electricity, fuel, fixed capital, fish respiration, and liquid oxygen in two locations by 4 stage running water type farm size of small, small and medium, large and medium, large scale. The result showed that the mean GHG emissions were $36.83kg{\cdot}CO_2/year$ in the southern sea and $24.33kg{\cdot}CO_2/year$ in Jeju-Do, respectively, in the stage of production per fish 1kg at 2 locations and farm size from domestic farmed flounders, and it will give to be useful for policy, planning, and regulation of aquaculture development with establishing GHG reduction standards.

• Ocean and Polar Research
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• v.34 no.1
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• pp.65-71
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• 2012

Gambierdiscus toxicus, Adachi et. Fukuyo, is a benthic ciguatoxin-producing armored dinoflagellate, often attached to macroalgae. This organism is the primary causative agent of ciguatera fish poisoning which occurs in tropical and subtropical regions. However, regardless of the fact that the population of Gambierdiscus spp. has expanded to such temperate areas from sub-trophic and trophic areas, monitoring of G. toxicus has been lacking in the Korean coastal waters of temperate areas. This study was performed at the uninhabited Baekdo Islands off the southern coast of Korea and at Seopsom Island in the vicinity of Seogwipo, Jeju Province during April and May, 2011. Cell densities of Gambierdiscus spp. on macroalgae at Baekdo and Jeju Island ranged from zero to 56.4 cells $g^{-1}$. Maximum density was recorded on the brown alga Cladophora japonica at St. 3 of Jeju Island. In particular, the cell densities of Gambierdiscus spp. were influenced by the substrate characteristics of macroalgae. In the future, the continuous monitoring of toxic benthic dinoflagellate is necessary to predict and prevent ciguatera poisoning in Korean coastal waters.

• Ocean and Polar Research
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• v.24 no.3
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• pp.189-196
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• 2002

A multichannel seismic survey was conducted in the southern Ayu Trough which is the only spreading boundary between the Philippine Sea and Caroline plates. The seismic system used in this study comprises of 2.46-l sleeve gun and a 12-channel streamer with a group interval of 6.25m. Migration technique was used to analyze seismic velocity, and poststack depth migration was applied to the stacked data. The sediment thickness obtained from the depth section tends to increase with distance from the spreading axis. Sedimentation rates are poorly constrainted in the study area. The apparent half-spreading rates estimated from the sediment thickness and sedimentation rate from DSDP hole on the caroline plate are 4.7mm/yr and 7.9mm/yr at $1^{\circ}24'N\;and\;0^{\circ}42'N$, respectively, which are fester than Previously suggested. On the basis of new oblique spreading geometry, the recalculated spreading rates are 5.4mm/yr and 9.1mm/yr at $1^{\circ}24'N\;and\;0^{\circ}42'N$, respectively. Seismic sections show that the topography is asymmetric across the Ayu Trough and the acoustic basement is rough. These features are consistent with the earlier suggestion that the Ayu Trough is a slow-spreading divergent boundary. A detailed examination of seismic profiles away from the axis shows that sediments can be divided into two layers which implies a possible change in the spreading rate anuor sedimentation condition during the formation of the trough.

• Ocean and Polar Research
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• v.24 no.3
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• pp.289-300
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• 2002

The Lago Sofia conglomerates encased in the Cretaceous Cerro Toro Formation, southern Chile, represent a gigantic submarine channel system developed along a foredeep trough. The channel system consists of several tributaries along the trough margin and a trunk channel along the trough axis. Voluminous debris flows were generated ubiquitously along the tract of the submarine channel mainly by the failure of nearby channel banks or slopes. The flows transformed immediately into multiphase flows and resulted in very thick-bedded mass-flow deposits with a peculiar structure sequence. The mass-flow deposits commonly overlie fluted or grooved surfaces and consist of a lower division of clast-supported and imbricated pebble-cobble conglomerate with common basal inverse grading, and an upper division of clast- to matrix-supported and disorganized pebble conglomerate or pebbly mudstone with abundant intraformational clasts. The structure sequence suggests a temporal succession of a turbidity current, a bipartite hyperconcentrapted flow with active clast collisions near the flow base, and a cohesive debris flow probably with a rigid plug. The multiphase flow is interpreted to have resulted from transformation of clast-rich but cohesive debris flows. Cohesive debris flows appear to transform more easily into dilute flow types in subaqueous environments because they are apt to hydroplane. This is in contrast to the flow transitions in subaerial environments where noncohesive debris flows are dominant and difficult to hydroplane.

• Ocean and Polar Research
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• v.29 no.1
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• pp.1-8
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• 2007

A series of long chain unsaturated ketone (alkenone) was identified in the particulate organic matter sampled from surface water of the eastern South Sea, Korea. The seawater temperature based on the $C_{37}$ alkenone was calculated by using several different equations of unsaturation index(${U^{K'}}_{37}$), compared with in situ CTD temperature. Among the previously reported equations, the equation(0.044T-0.204) which was proposed by Sawada et al.(1996) seems to be the most useful for the calculation of $C_{37}$ alkenone temperature, showing average $0.51^{\circ}C$ difference between ${U^{K'}}_{37}$ temperature and in situ CTD temperature. This result suggest that alkenone should be a useful molecular biomarker for reconstructing paleo-environmental change in the South and East Sea, Korea. However, it is required to establish more reliable equation for the calculation of $C_{37}$ alkenone temperature.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.4
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• pp.265-275
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• 2011

Estimation of wave height is the most important factor in the design of coastal structures such as breakwaters. In the present study, typhoon wind distribution was constructed by applying the parametric model of Holland (1980), and numerical simulations on the typhoon-generated waves were carried out using the WAM. The typhoons which affected the southern coast of the Korean Peninsula and several hypothetical typhoons were selected to construct the training sets. Design wave heights were estimated using the empirical simulation technique for various return periods and wave directions. The estimated design wave heights were compared with those by the peaks-over-threshold method and the results of KORDI(2005).

• International Journal of Ocean System Engineering
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• v.3 no.3
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• pp.152-157
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• 2013

This study, a new concept design of the stem and aims to determine the suitability of various carbon/PEEK composite designs for artificial hip joints. Shear stress tested with alternative materials of the Ti-based stem for artificial hip joints. In addition, FEA is conducted according to the fiber ply orientation and the load condition for carbon/PEEK composites. The stem shape of two types was designed through the shape normal of the femur. Multidirectional load cases were used for each FEA model. In the case of general shape, the results show that the stress of ply orientation case II was lower than for cases I and III. On the other hand, in the case of the curved shape, ply orientation case I was lowest. In the case of the Ti stem, the stress of the curved shape was 18% lower than the general shape.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.3
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• pp.264-269
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• 2021

A single postlarva (9.72 mm in standard length) specimen of Crossorhombus azureus (Alcock, 1889) belonging to the family Bothidae, was collected using a bongo net from the southern sea of Korea on December 10, 2019. This species is characterized by having spines on post basipterygial processes. It has two eyes located at the opposite side in head, which accordingly belongs to pre-metamorphosis stage. Melanophores are distributed on the dorsal and anal fin base on the right side (blind side), which is regarded as a useful identification key distinguishing C. azureus from congeneric species in their postlarval stage. A molecular analysis based on mitochondrial DNA COI sequences showed that our specimen was closely matched to adult C. azureus (K2P distance = 0.017). As there is no Korean name for the genus Crossorhombus in spite of presence of Crossorhombus kobensis and its Korean name "Go-be-dung-geul-neob-chi" in Korea, we proposed a new Korean name "Dung-geul-neob-chi-sog" for the genus Crossorhombus and "Pa-lang-dung-geul-neob-chi" for the species C. azureus.

• Steel and Composite Structures
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• v.47 no.5
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• pp.615-631
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• 2023

Steel corrosion induces structural deterioration of concrete-filled steel tubes (CFSTs), and any potential extreme action on a corroded CFST would pose a severe threat. This paper presents a comprehensive investigation on the lateral impact behaviour of CFSTs suffering from localised pitting corrosion damage. A refined finite element analysis model is developed for the simulation of locally corroded CFSTs subjected to lateral impact loads, which takes into account the strain rate effects on concrete and steel materials as well as the random nature of corrosion pits, i.e., the distribution patterns and the geometric characteristics. Full-range nonlinear analysis on the lateral impact behaviour in terms of loading and deforming time-history relations, nonlinear material stresses, composite actions, and energy dissipations are presented for CFSTs with no corrosion, uniform corrosion and pitting corrosion, respectively. Localised pitting corrosion is found to pose a more severe deterioration on the lateral impact behaviour of CFSTs due to the plastic deformation concentration, the weakened confinement and the reduction in energy absorption capacity of the steel tube. An extended parametric study is then carried out to identify the influence of the key parameters on the lateral impact behaviour of CFSTs with localised pitting corrosion. Finally, simplified design methods considering the features of pitting corrosion are proposed to predict the dynamic flexural capacity of locally pitted CFSTs subjected to lateral impact loads, and reasonable accuracy is obtained.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.3
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• pp.286-295
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• 2016

With the results of observations in 2013 and 2014 including ocean buoys, in-situ investigations and wind data, we examined the spatio-temporal variation of cold water masses along the eastern coast of Korea. Usually, a cold water mass first appears along the northern part of the eastern coast from May to July, and then along the southern part of the eastern coast from late June to mid-August. Cold water masses appear 3~5 times a year and remain for 5~20 days in the southwestern part of the East Sea. A distinctive cold water mass appeared usually in mid-July in this area, the surface temperature of which was below $10^{\circ}C$ in some cases. During the appearance of a cold water mass in the southwestern part of the East Sea, the horizontal temperature gradient was large at the surface and a significant low water temperature below $8^{\circ}C$ appeared at the bottom level. This appearance of cold water masses clearly corresponded to southwesterly winds, which generated coastal upwelling.