• 한국CDE학회논문집
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• 제19권1호
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• pp.41-49
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• 2014

For the reuse of the existing 3D block model of a ship, we analyze the hull modeling process using AVEVA Marine which is a representative CAD (Computer-Aided Design) system for the shipbuilding. In the AVEVA Marine environment where the design engineer makes 3D model on the 2D view that is so-called 2.5D, it cannot be possible to copy to reuse the block model just simply copying the 3D feature model itself like in the general mechanical CAD system or Smart Marine 3D which are on the basis of the 3D model representation. In this paper, we analyze the scheme file where the 3D model is defined in AVEVA Marine so that we develop the program for the block copy and the translation using this scheme file. It is significant that this program can be immediately available as a real-world application on the AVEVA Marine environment.

• 인터넷정보학회논문지
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• 제23권1호
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• pp.39-47
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• 2022

디지털트윈은 현실데이터를 수집하고 가상공간을 구현하는 측면에서 핵심 인프라에 대한 디지털 관리체계 구축의 하나로 자리 잡고 있다. 하지만 현재 국내에는 3차원 기반의 통합적인 해양정보 분석도구 및 기술이 부재하며, 육상과 달리 유동적인 해양정보를 디지털화하기 위해서는 새로운 3D모델링 기술과 자료처리 기술이 요구되나 추진에 한계가 존재한다. 이에 본 연구에서는 해양 디지털트윈 관련 동향과 디지털트윈 기술 요소를 분석하여 향후 해양 디지털트윈의 구조, 데이터, 모델링, 활용 플랫폼 4가지 부문으로 개발 방향을 제시하고자 한다.

• Journal of Power Electronics
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• 제15권3호
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• pp.741-752
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• 2015

This study proposes a new solution for the parallel operation of microgrid inverters in terms of circuit topology and control structure. A combined three-phase four-wire inverter composed of three single-phase full-bridge circuits is adopted. Moreover, the control structure is based on adaptive three-order sliding-mode control and wireless load-sharing control. The significant contributions are as follows. 1) Adaptive sliding-mode control performance in inner voltage loop can effectively reject both voltage and load disturbances. 2) Virtual resistive-output-impedance loop is applied in intermediate loop to achieve excellent power-sharing accuracy, and load power can be shared proportionally to the power rating of the inverter when loads are unbalanced or nonlinear. 3) Transient droop terms are added to the conventional power outer loop to improve dynamic response and disturbance rejection performance. Finally, theoretical analysis and test results are presented to validate the effectiveness of the proposed control scheme.

• 해양환경안전학회지
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• 제18권6호
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• pp.577-583
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• 2012

부유구조물은 해양에서 다양한 외력을 경험하게 되며 특히, 파랑하중은 구조물의 설계에 결정적인 지배인자로 간주되고 있다. 이런 구조물은 파장과 크기의 상대적 관계로 소형구조물, 대형구조물 등으로 구분될 수 있으며 전통적으로 소형구조물은 회절발생이 없는 것으로 가정하며 대형구조물은 회절 작용에 따른 관성력만을 고려하여 파랑하중을 산출한다. 따라서 이 연구에서는 해양과 강, 호수 등에서 주로 사용되고 있는 정사각형 부유구조물을 이용하여 동유체력과 구조응답의 상관관계를 파악하여 장방형 부유구조물의 안전성에 대한 영향을 검토하였다.

• Fisheries and Aquatic Sciences
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• 제14권1호
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• pp.16-21
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• 2011

The genetic diversity and population genetic structure of thread-sail filefish, Stephanolepis cirrhifer (Temminck & Schlegel), were examined with a nucleotide sequence analysis of a 495bp fragment of the 5'-end of the cytochrome b gene in 113 fish collected from five populations from the south and east coasts of the Korean Peninsula. Seventeen variable nucleotide sites and 16 haplotypes were defined. The observed haplotypes had a shallow haplotype genealogy and no geographical association. Most of the populations had high haplotype diversity and low nucleotide diversity, and significant negative values for Fu's $F_S$, suggesting rapid, recent population growth from an ancestral population and sudden population expansion. The estimated pairwise fixation indices ($F_{ST}$) indicate that substantial gene flow occurs among these populations. Thread-sail filefish in the South Sea of Korea and East Sea Korean populations forms a single panmictic population. Thus, thread-sail filefish in these areas should be treated as one management unit.

• Ocean and Polar Research
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• 제26권2호
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• pp.265-272
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• 2004

This study was conducted to investigate the community structure and distributional pattern of meiobenthos in the deep-sea bottom of the Clarion-Clipperton Fracture Zone of northeastern Pacific during July 2001. Examination of sediment samples collected on the eight survey station showed that there were 10 different types of meiobenthos. The most abundant meiobenthic animals were nematodes in all stations. Sarcomastigophorans, benthic harpacticoids were next abundant meiobenthos. Vertical distribution of meiobenthic animals showed the highest individual numbers in the surface sediment layers of 0-1 cm depth and showed more steep decreasing trend as sediment gets deeper on the stations of high latitude located in $16-17^{\circ}N$. Horizontal distribution of meiobenthic animal in the study area within CCFZ showed high densities of meiobenthos at the stations had few manganese nodules on their sediment surface in the site of low latitude. For size distribution analyses showed that animals which fit into the sieve mesh size of 0.063 mm were abundant.

• 수산해양교육연구
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• 제27권1호
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• pp.300-307
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• 2015

Seasonal variation in marine macroalgal community structure was examined at the intertidal zones of Geumgap, Jindo, Korea, from October 2013 to August 2014. In total, 56 macroalgal species were identified, including 9 green, 12 brown, and 35 red algae. Annual seaweed biomass was 548.96 g wet wt. /$m^2$ with seasonal range between 371.08 g wet wt. /$m^2$ at summer and 32.91 g wet wt. /$m^2$ at winter. The dominant seaweed in terms of biomass was Sargassum thunbergii and subdominant species were Gelidium elegans, Sargassum fusiforme, and Ishige okamurae. The vertical distribution of seaweeds from the upper to lower intertidal zones was Gloiopeltis spp., Ulva spp.- S. thunbergii, S. fusiforme, Ishige okamurae - S. thunbergii, S. fusiforme, G. elegans. Annual seaweed coverage, richness index (R), evenness index (J'), and diversity index (H') values were 27.95%, 6.10, 0.38, and 1.38, respectively. Coarsely branched form was the most dominant functional group in terms of species number and biomass among benthic macroalgal species.

• 한국수산과학회지
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• 제51권5호
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• pp.571-578
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• 2018

Seasonal variability in algal community structure of the subtidal zone was examined at four study sites on the southeastern coast of Korea from February to November 2016. A total of 81 species of algae (8 green, 12 brown, and 61 red) were indentified. During the study period, the greatest number of species was observed at Sinamri (57 species) followed by Daesongri (50 species), Dongbaekri (47 species) and Gangyangri (42 species). Of the six functional seaweed forms, the coarsely-branched form was the most dominant, accounting for about 43% of the total species at Daesongri. The annual average biomass in wet weight varied from $700.59g/m^2$ at Sinamri to $1,712.45g/m^2$ at Daesongri. The parameters of seaweed community structures were as follows: dominance index (DI), 0.30-0.54; richness index (R), 4.92-7.05; evenness index (J'), 0.54-0.72; and diversity index (H'), 2.05-2.91.

• Ocean Systems Engineering
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• 제1권1호
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• pp.17-28
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• 2011

The purpose of this paper is to demonstrate the efficacy of modeling a surface effect ship's air-cushion flexible seal utilizing a two-dimensional beam under steady state conditions. This effort is the initial phase of developing a more complex three-dimensional model of the air-seal-water fluid-structure interaction. The beam model incorporates the seal flexural rigidity and mass with large deformations while assuming linear elastic material response. The hydrodynamic pressure is derived utilizing the OpenFOAM computational fluid dynamic (CFD) solver for a given set of steady-state flow condition. The pressure distribution derived by the CFD solver is compared with the pressure required to deform the seal beam model. The air pressure, flow conditions and seal geometry are obtained from experimental analysis. The experimental data was derived from large-scale experimental tests utilizing a test apparatus of a canonical surface effect ship's flexible seal in a towing tank over a variety of test conditions.

• 동력기계공학회지
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• 제22권1호
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• pp.25-33
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• 2018

The safety of structure was evaluated by taking into consideration the complex marine environmental conditions of the Lattice boom crane, which is widely used in offshore plants due to less influence by wind. CFX analysis was carried out to take into account the influence of wind speed, and the result was applied as a boundary condition to perform static analysis according to the luffing angles of $28^{\circ}$, $61^{\circ}$, and $80^{\circ}$ in the on board and off board, respectively. In addition, the Lattice Boom Crane is large slender structure, and the possibility of buckling is interpreted under three conditions where the biggest stress occurs. All conditions satisfied the safety requirements of the Classification Regulations. Also, as a result of the buckling analysis, the load less than the critical load was applied so buckling does not occur.