• Title/Summary/Keyword: Sea test-bed

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Design and Implementation of A Hovering AUV with A Rotatable-Arm Thruster (회전팔 추진기를 가진 시험용 HAUV의 설계 및 구현)

  • Shin, Dong H.;Bae, Seol B.;Joo, Moon G.;Baek, Woon-Kyung
    • IEMEK Journal of Embedded Systems and Applications
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    • v.9 no.3
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    • pp.165-171
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    • 2014
  • In this paper, we propose the hardware and software of a test-bed of a hovering AUV (autonomous underwater vehicle). Test-bed to develop as the underwater robot for the hovering -type is planning to apply for marine resource development and exploration for deep sea. The RTU that controls a azimuth thruster and a vertical thruster of test-bed is a intergrated-type thruster. The main control unit that collects sensor's data and performs high-speed processing and controls a movement of test-bed is a underwater hybrid navigation system. Also it transfers position, posture, state information of test-bed to the host PC of user using a wireless communication. The host PC checks a test-bed in real time by using a realtime monitoring system that is implemented by LabVIEW.

Survey of Seafloor at Chagwi-do of Jeju Island to Select 60-m-class Sea Test Bed of Wave Energy Converter (60m급 파력발전 실해역 시험장 선정을 위한 제주도 차귀도 해역의 해저 지층 탐사)

  • Kim, Hansoo;Kim, Jeongrok;Cho, Il-Hyoung;Paeng, Dong-Guk;Choi, Jong-Su
    • Journal of Ocean Engineering and Technology
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    • v.31 no.4
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    • pp.308-314
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    • 2017
  • The purpose of this study was to investigate the sea floor using a seismic profiler in the northern part of Chagwi-do of Jeju Island in order to select the optimal location for the 60-m-class berth of a sea test bed for wave energy converters and provide basic environmental data for designing a suction anchor. The echo types of the seismic profiles were classified based on the study of Kim et al. (2016a), and the location for installing the suction anchor was selected based on a sediment thickness of more than 10 m. The physical properties of the surface sediments were determined by analyzing the sediment samples obtained from 16 grab sample points. Based on the investigation and analysis, we proposed a survey area in the North-Eastern sea as an optimum location for the 60-m-class berth where the suction anchor could be installed.

Distribution Pattern of the Sea Urchin Strongylocentrotus nudus in Relation to Predation Pressure in Hosan, the East Coast of Korea (동해안 삼척 호산에 서식하는 둥근성게 Strongylocentrotus nudus의 분포와 피식 패턴)

  • 유재원;손용수;이창근;김정수;한창훈;김창수;문영봉;김동삼;홍재상
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.9 no.1
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    • pp.40-49
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    • 2004
  • An ecological study on a sea urchin population, Strongylocentrotus nudus, a key role species in recovery of macroalgal bed, was conducted in Hosan, Samcheok area on the east coast of Korea. Three experimental plots, namely, AMB (artificially-restored macroalgal bed), BG (barren grounds) and NMB (natural macroalgal bed) were established after a pilot survey in June 2002. Distribution and abundance, grazing rates, predation pressure and predator guilds on S. nudus were estimated in three plots bimonthly from Aug. to Dec., 2002. Abundance of S. nudus was lowest, but median test diameter of the urchin was highest (Kruskal-Wallis test, p-value, p<0.001 in Aug. and p=0.003 in Oct.) in NMB In-situ grazing rate of S. nudus estimated by enclosure cage experiment in NMB was about 12 times higher in Aug. (160.0 mg seaweed/g sea urchin/day) than in Oct. (13.8). Predation intensity measured by tethering experiment was higher in NMB. Most of the predators on S. nudus were invertebrates and no fish predators were found. Predator guilds identified by the fish trap experiment using live or dead sea urchins included who]ks Neptunea arthritica, starfish Asterina pectinifera, hermit crabs Pagurus of. samuelis, Paguristes barbatus, brown shawl crabs Atergatis integerrimus and crabs Actaea subglobosa. High predation pressure on S. nudus in natural macroalgal beds was the likely cause of its low density. Elevated sea urchin density and the consequent lasting deforestation of macroalgae in barren grounds demonstrate the importance of predation pressure on sea urchins.

A Study on the Characteristics of Infiltration of Sea Dyke by Field Investigation and Seepage Model Test (현장조사와 침투모형시험을 통한 방조제 침투특성 연구)

  • Park, Choon-Sik;Kim, Jong-Hwan;Lee, Sun-Il
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.24 no.4
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    • pp.247-256
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    • 2012
  • The purpose of this study is to decide the permeability and the rate of flow in a way of both site investigation and backward analysis and the most reasonable numerical analysis by performing a seepage model test for measuring the deformation swept volume of the embankment body in order to review a stability of the sea dyke being composed of multi-layers depending on variation of infiltration. As a result of the review, it could be forecasted that sweeping loss would be taken place at the boundary between bed protection works and embankment materials of the sea dyke due to a permeability difference of the multi-layered bed foundation structures and the sea dyke deformation would be occurred as a result thereby. As result of a numerical analysis for the seepage model test, it could be observed that critical velocity method was found to be smaller than the numerical analysis value but its tendency was similar and therefore it was judged that this method could be applied for the actual cross section.

The sea Trial of Deep-sea Crabster CR6000 System (심해용 크랩스터 CR6000 시스템의 실해역 시험 결과)

  • Jun, Bong-Huan;Yoo, Seong-Yeol;Lee, Pan-Mook;Park, Jin-Yeong;Shim, Hyungwon;Baek, Hyuk
    • IEMEK Journal of Embedded Systems and Applications
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    • v.12 no.5
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    • pp.331-341
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    • 2017
  • This paper presents the sea-trial results of Crabster CR6000 which is a deep-sea walking robot developed by KRISO in 2016. Crabster CR6000 is designed to inspect deep-sea environment rejecting the disturbance on the silent and calm abyssal area. The sea-trial was conducted at the East Sea and the Philippine Sea on December 2016. The Crabster CR6000 undocked successfully from the Shuttle after touchdown on the sea-bed and walked out on the soft sediment soil of the 4,743m seafloor at the fourth diving in the Philippine Sea. The advanced technologies and capabilities of CR6000 were verified from the operational and functional test conducted in the sea-trial. The experimental data acquired from the sea-trial were summarized and the first experience of the deep-sea walking robot was presented in this paper.

Temporal and Spatial Spreading Characteristic of Drift Soil due to the Reclamation in the Pusan Port (해양 매립 및 준설토 투기에 따른 부유사 확산의 시.공간적 특성에 관한 연구)

  • 김용원;김종인;윤한삼;홍도웅
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2000.10a
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    • pp.196-203
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    • 2000
  • In this study, the evaluation method of diffusion characteristics of Suspended Soli&SS) and the generation limit(source and thick) are investigated, which is significantly affecting on marine examined by construction works such as dredging and reclamation. Dispersion characteristics of SS is examined by hydraulic tests and numerical works in consideration with the Pusan Port. Hydraulic model test was performed in 2-D wave flume to find the limit wave conditon of re-suspension of solid as well as the time dependent characteristics of settlement The results obtainded in the study are as follows; 1) The quantituative evaluation af SS is the basic parameter of marine environmental impact assessment in related with the port development The SS increases as the water content of sea bed solid increases and the density decreases. 2) The sea bed solid in Sinsundai area, Pusan Port has the water content range of 83~157% 3) The ratio of suspension velocity against settlement velocity is about 0.25 and SS concentration converges as the wave heigh. 4) The SS increases 2 time when time step increases 3 time(10 sec to 30 sec) in numerical simulation It means that the effect of the time step should be checked in detail to stable. The diffusion The diffusion coefficient are Affiected senstively in the dispersion process while sea ved friction coefficinet have not strong relation in the simulated area

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Ecotoxicological Evaluation of Sewage Sludge Using Bioluminescent Marine Bacteria and Rotifer

  • Park, Gyung-Soo;Chung, Chang-Soo;Lee, Sang-Hee;Hong, Gi-Hoon;Kirn, Suk-Hyun;Park, Soung-Yun;Yoon, Seong-Jin;Lee!, Seung-Min
    • Ocean Science Journal
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    • v.40 no.2
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    • pp.91-100
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    • 2005
  • Bioassay using the marine bacteria, Vibrio fischeri and rotifer, Brachionus plicatilis, and chemical analyses were conducted to assess the toxicity of the various sewage sludges, one of the major ocean dumped materials in the Yellow Sea of Korea. Sludge elutriates extracted by filtered seawater were used to estimate the ecotoxicity of the sludge. Chemical characterization included the analyses of organic contents, heavy metals, and persistent organic pollutants in sludge. Bacterial bioluminescent inhibition (15 min), rotifer mortality (24 hr) and rotifer population growth inhibition (48 hr) assay were conducted to estimate the sludge toxicity. EC50 15 min (inhibition concentration of bioluminescence after 15 minutes exposed) values by Microtox(R) bioassay clearly revealed different toxicity levels depending on the sludge sources. Highest toxicity for the bacteria was found with the sludge extract from dyeing waste and followed by industrial waste, livestock waste, and leather processing waste. Clear toxic effects on the bacteria were not found in the sludge extract from filtration bed sludge and rural sewage sludge. Consistent with Microtox(R) results, rotifer neonate mortality and population growth inhibition test also showed highest toxicity in dyeing waste and low in filtration bed and rural sewage sludge. High concentrations of persistent organic pollutants (POPs) and heavy metals were measured in the samples from the industrial wastes, leather processing plant waste sludge, and urban sewage sludge. However, there was no significant correlation between pollutant concentration levels and the toxicity values of the sludge. This suggests that the ecotoxicity in addition to the chemical analyses of various sludge samples must be estimated before release of potential harmful waste in the natural environment as part of an ecological risk assessment.

Installation of Meteorological Mast for the Test Bed of Offshore Wind Power (서해 100MW 해상풍력 실증단지 기상타워 구축사례)

  • Ryu, Moosung;Kang, Keumseok;Kim, Jiyoung;Lee, Junshin
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.55.2-55.2
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    • 2011
  • The final site of offshore wind power plant should be decided by comprehensive examination of various conditions such as wind resource, sea depth, geology, grid connection, social circumstance and environmental issue. Wind condition is typically regarded as the most important factor because wind energy increases in proportion to wind velocity and it directly relates to the amount of power output, efficiency of power plant and profitability. Advanced countries in the offshore wind power sector such as Denmark, UK and Germany, they are analyzing wind resource accurately by installing the meteorological mast in the ocean in order to get the optimal type of wind turbine and maximum generation efficiency. Also, it is made much of designing offshore power plant on the basis of actual measurement by met-mast and those wind farms have a chance to get the loan with reduced interest rate in project financing. In Korea, the HEMOSU-1 is installed in the ocean around Wido island to analyze wind resource of test bed of 100MW offshore wind power on october last year. This paper deals with the design and construction procedure of the first met-mast in Korea and also shows the site characteristics of test bed. Therefore, this paper will give useful information to local governments and private business sector who are trying to construct offshore wind farm and it can also be a good reference for the following projects of meteorological mast in near future.

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A Study on the Evaluation of Dynamic Behavior and Liquefaction Cau8ed by Earthquake of Sea Dike Structures on the Ground (방조제 축조 예정지반의 지진에 의한 액상화 거동 평가)

  • 도덕현;장병욱;고재만
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.35 no.2
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    • pp.43-56
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    • 1993
  • The laboratory tests are performed on how the liquefaction potential of the sea dike structures on the saturated sand or silty sand seabed could be affected due to earthquake before and after construction results are given as follows ; 1. Earthquake damages to sea dike structures consist of lateral deformation, settlement, minor abnormality of the structures and differential settlement of embankments, etc. It is known that severe disasters due to this type of damages are not much documented. Because of its high relative cost of the preventive measures against this type of damages, the designing engineer has much freedom for the play of judgement and ingenuity in the selection of the construction methods, that is, by comparing the cost of the preventive design cost at a design stage to reconstruction cost after minor failure. 2. The factors controlling the liquefaction potential of the hydraulic fill structure are magnitude of earthquake(max. surface velocity), N-value(relative density), gradation, consistency(plastic limit), classification of soil(G & vs), ground water level, compaction method, volumetric shear stress and strain, effective confining stress, and primary consolidation. 3. The probability of liquefaction can be evaluated by the simple method based on SPT and CPT test results or the precise method based on laboratory test results. For sandy or silty sand seabed of the concerned area of this study, it is said that evaluation of liquefaction potential can be done by the one-dimensional analysis using some geotechnical parameters of soil such as Ip, Υt' gradation, N-value, OCR and classification of soils. 4. Based on above mentioned analysis, safety factor of liquefaction potential on the sea bed at the given site is Fs =0.84 when M = 5.23 or amax= 0.12g. With sea dike structures H = 42.5m and 35.5m on the same site Fs= 3.M~2.08 and Fs = 1.74~1.31 are obtained, respectively. local liquefaction can be expected at the toe of the sea dike constructed with hydraulic fill because of lack of constrained effective stress of the area.

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Phytoplankton as Standard Test Species for Marine Ecotoxicological Evaluation (해양생태독성평가를 위한 표준시험생물로서의 식물플랑크톤에 관한 연구)

  • Park Gyung-Soo;Lee Sang-Hee;Lee Seung-Min
    • Journal of Environmental Science International
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    • v.14 no.12
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    • pp.1129-1139
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    • 2005
  • A series of experiments was conducted to identify the potential of five phytoplankton species as standard test species for marine ecotoxicological tests. The candidate phytoplankton species are Skeletonema costatum, Heterosigma akashiwo, Prorocentrum micans, Isochrysis galbana, and Tetraselmis suecica. Salinity tolerance and sensitivity on potassium dichromate as a reference material were identified. Toxicity of eleven ocean dumped sewage sludges and four red tide expellent extracts were estimated by the inhibition of population growth rates (PGR) of marine diatom S. costatum, While most species revealed relatively weak tolerance on salinity, T. suecica demonstrated the highest salinity tolerance ranged from $5\~35$ psu and the others $15\~35$ psu. H. akashiwo revealed the highest sensitivity as 72h $IC_{50}$=0.76mg/L and T. suecica the lowest as 72h $IC_{50}$=8.89mg/L on potassium dichromate. Sludge extracts from industrial waste, domestic sewage and livestock farm waste sludge showed high toxicity as 72h $IC_{50}$<$2\%$ and lowest toxicity from filtration bed sludge as 72h $IC_{50}$=$30.50\%$ NOEC (No Observed Effective Concentration) of sludge extract ranged from <$0.4\%$ to $1.6\%$ and this indicated high phytotoxicity of ocean dumped sewage sludge. The test sensitivity of phytoplankton PGR inhibition was much higher than those of marine rotifer Brachionus plicatilis mortality test and bioluminescent inhibition test by marine bacteria Vibrio fischeri, and comparable with the sea urchin (Strongylocentrotus intermedius) fertilization test. As a result the phytotoxicity test using phytoplankton PGR inhibition ($IC_{50}$) must be a useful tool for marine phyto-toxicological evaluation of ocean dumped materials.