• Journal of Ocean Engineering and Technology
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• v.37 no.6
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• pp.247-255
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• 2023

Interference and collisions often occur in the loading process at shipyards. Existing simulation methods focus primarily on resource processes and schedules, and there is a lack of real-time reflection in the complex and highly variable loading process. This study aims to develop a spatial environment incorporating real-time product data, such as hulls, and confirms its effectiveness by simulating various construction scenarios. As a method, a near real-time spatial environment based on broadband laser scanning was established, with the situation of loading heavy cargo assumed when converting an existing ship into an LNG dual-fuel propulsion ship. A case study simulation of near-real-time cargo loading processes was then conducted using Unity 3D to confirm the interference and collision risks within the spatial environment. The results indicated that interference occurred in structures previously not identified in the design data, and a collision occurred during the loading object erection phase. The simulation confirmed that the identification of interference and collision risks during the erection phase highlights the need for a relocation or removal process of potential hazards before erection takes place. An improved erection simulation that integrates near real-time data could effectively prevent interference and collision risks.

• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.157-165
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• 2010

In June 2010, Geostationary Ocean Color Imager (GOCI), the world's first ocean color observation satellite will be launched. GOCI is planned for use in real-time monitoring of the ocean environment around Korean Peninsula by daily analysis of ocean environment measurements of chlorophyll concentration, dissolved organic matter, and suspended sediments taken eight times per day for seven years. GOCI primary data will support a fishery information service and red tide forecasting, and ocean climate change research. In this paper, the development background of GOCI, user requirements, GOCI architecture, and the GOCI on-orbit operational concept are explained.

• Development and Reproduction
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• v.17 no.3
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• pp.257-268
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• 2013

Morphometric changes in the Ussurian bullhead, Leiocassis ussuriensis, and the Korean bullhead, Pseudobagrus fulvidraco, were observed during the early period of growth. Yolk length, yolk height, and yolk volume in the two species decreased within 9 days post-hatching (DPH) (p<0.05). The body lengths and body heights of both species increased gradually to 150 and 130 DPH, respectively (p<0.05). The horizontal distance between the anteriormost extension of the head and the anterior insertion of the pectoral fin, the anteriormost extension of the head ${\times}$ the verticality position of the anterior insertion of the primary dorsal fin rays, and the anterior insertion of the primary dorsal fin ${\times}$ the anterior insertion of the pectoral fin were greater in the Korean bullhead than in the Ussurian bullhead (p<0.05). However, the relative sizes of the head region, pectoral fin, ventral fin, and anal fin were greater in the Ussurian bullhead than in the Korean bullhead (p<0.05), and relative body depth and the size of the outer-mandible barbel were greater in the Korean bullhead than in the Ussurian bullhead (p<0.05). The growth curves of the morphometric characteristics of both species were divided into three types.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.5
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• pp.530-537
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• 2008

Austenitic stainless steels(SUS 304, SUS 316), which are used for safety control valve of LNG carrier, are occasionally exposed in the cryogenic environment. In this regards, it is required to evaluate the mechanical characteristics under the low temperature environment. In this study, a series of uniaxial tensile test was carried out varying temperature for austenitic stainless steel. The phenomena of the strain-induced plasticity have been observed on the all temperature ranges. The critical value for threshold of 2nd hardening due to the phase transformation induced plasticity as well as the increase of hardening have been reported. The summarized experimental results would be used for the validation of numerical techniques applicable for the nonlinear hardening behavior of austenitic stainless steel under the cryogenic temperature environment.

• Ocean and Polar Research
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• v.27 no.4
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• pp.397-417
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• 2005

Phytoplankton community structure and distribution pattern in the surface water around the Ieodo Ocean Research Station were investigated during seven cruises carried out from July, 2003 to October, 2004. Samples were analyzed using various tools including a microscope, flow cytometer, and HPLC. Satellite images were used to analyze spatio-temporal phytoplankton biomass distribution. SeaWiFS chlorophyll a (chl a) images showed that spring blooms occurred in April-May near the Ieodo Station, and these waters were under the influence of Changjiang Dilute Water during July-October. Also, during the July-October period, HPLC pigments data showed increasing zeaxanthin concentrations, a marker pigment of cyanobacteria whereas increasing concentrations of various other pigments such as fucoxanthin, peridinin, prasinoxanthia alloxanthin, 19'-hexanoyloxyfucoxanthin and chlorophyll b were noted during spring blooms. Such pigment marker data were consistent with picoplankton data analyzed by flow cytometer and nano-microplankton analyzed by microscope. The pigment-CHEMTAX method was used to drive the phytoplankton group apportioned chi a. Diatoms, chlorophytes, dinoflagellates, and cryptophytes comprised 25.8, 20.7, 15.9, and 14.1%, respectively, of the total chl a in May. Average cyanobacteria concentrations in July-October contributed 25.4% of the total concentration. This was the highest percent contribution and was followed by chlorophytes, diatoms, and prymnesiophytes. This study discusses results from various methods, similarities and differences in the results among those methods, and the application range of the results from different analytical methods. Also, the study reveals a detailed phytolpankton community structure in the waters around the Ieodo Station, and suggests future monitoring considerations in relation to cell morphology, ecology and diversity factors according to taxonomic groups.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.142-146
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• 2007

Ambient noise was measured for 3 hours on May, 2001 at a site of 20 m water depth in the Korean coast of the Yellow Sea. During the measurement, the strong underwater sound assuming by marine life was continually observed. The spectrum level of this sound was very high compared to that of underwater ambient noise over the frequency range from 1 to 20 kHz. Therefore, this underwater sound can continually affect the ambient noise level. In this study, the source of the underwater sound was investigated. The snapping shrimp was estimated as reliable source. It was confirmed through comparison with experimental results described in previously literatures. It was also confirmed through analysis of snapping shrimp sound measured under laboratory conditions.

• The Journal of the Korea Contents Association
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• v.6 no.9
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• pp.164-173
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• 2006

As the CG images in the films and the games are getting more realistic by the development of computer graphics, the requests of technique that can develop the various digital contents has also increased. However, the techniques developed for the studies and simulations of the ecological system and adaptation in the ocean, are insufficient compared with those on the ground. This paper propose a method of modeling to simulate the growth of ocean objects according to the variation of virtual ocean environment and the efficient metamorphosis based on the movement of the objects. By modeling the ocean objects with the anisotropic metacubes, it is possible to represent easily the growth and metamorphosis of fishes as the movement in the virtual environment of ocean.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.304-306
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• 2003

Oceanic pycnocline depth is usually obtained from in situ measurements. As ocean internal waves occur on and propagate along oceanic pycnocline, it is possible to estimate the depth remotely. This paper presents a method for retrieving pycnocline depth from synthetic aperture radar (SAR) imagery where internal waves are visible. This model is constructed by combining a two-layer ocean model and a nonlinear internal wave model. It is also assumed that the observed groups of internal wave packets on SAR imagery are generated by local semidiurnal tides. Case study in East China Sea shows a good agreement with in situ CTD data.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.3
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• pp.354-365
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• 2019

Megabenthos samples were collected using 10-min trawls towed at 17 stations from 2015 to 2016. The dominant species (>1% of the total density) were Stegophiura sterea (10.4%) and two subtropical species, Mactrinula dolabrata (9.0%) and Acila divaricate (8.3%), respectively. The community structure of the megabenthos fell into four groups: the southeast, the southernmost region off Jeju Island, the frontal zone of the South Sea with C3, and a diagonal area from the south coast to the western side of Jeju Island. The total numbers of species, diversity, density and biomass were higher in the C3 region of the South Sea. Environmental factor analysis showed that differences in the megabenthos community were related to depth, gravel contents, and sorting value (${\sigma}$). These results indicate that changes in the marine environmental conditions in the South Sea of Korea affect the megabenthos species' composition and diversity.

• Ocean Systems Engineering
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• v.5 no.1
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• pp.21-30
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• 2015

This study is devoted to the optimal design of compressed bars under axial tensile or compressive forces and exposed to a corrosive environment. Dolinskii's linear stress corrosion model is adopted for analysis. Analytical and numerical results are derived for optimal variation of the cross-sectional area of the bar along its axis.