• Title/Summary/Keyword: Artificial Seabed

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An Experimental Investigation on the Hydrodynamic Characteristics of Submerged Artificial Seabed System in Regular Waves (중층계류식 인공해저시스템의 파랑중 운동특성에 관한 실험적 연구)

  • Yoon Sang-Joon;Yang Chan-Kyu;Kim Hyeon-Ju;Kim Heon-Tae
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.5 no.2
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    • pp.19-27
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    • 2002
  • This paper deals with the experimental investigation on the hydrodynamic behavior of the submerged artificial seabed system in regular waves. This system can function as a basis of seaweed forest which will cultivate coastal fishing ground and enhance coastal productivity. The experiment was conducted with the submerged rectangular plates of different length and depth in 2-D wave flume of KRISO/KORDI. The wave exciting forces, mooring line tension and 2-D motion response are measured and analyzed to figure out the design strategy.

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Acoustic Tracking of Fish Movements in an Artificial Reef Area Using a Split-beam Echo Sounder, Side-scan and Imaging Sonars at Suyeong Man, Busan, Korea (수영만 인공어초 해역에서 소너에 의한 어군의 유영행동 추적)

  • Lee, Dae-Jae
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.46 no.3
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    • pp.273-281
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    • 2013
  • The movement patterns of fish aggregations swimming freely near artificial reefs on August 24, 2006, at Suyeong Man, Busan, Korea, were acoustically investigated and analyzed. Acoustic surveys were conducted using a 70kHz split-beam echo sounder, 330 kHz side-scan sonar and a 310 kHz imaging sonar. Algorithms for tracking the movement of fish aggregations swimming in response to artificial reefs were developed. The travel direction and the swimming speed for two aggregations of fish were estimated from the trajectory orientations of echo responses recorded by the imaging sonar.The first group was floating just above the reef structure, while remaining in the midwater column, and the second group was swimming through and around artificial reefs near the seabed. The mean swimming speed was estimated to be 0.40 m/s for the midwater fish aggregation and 0.17 m/s for the bottom aggregation close to artificial reefs. These results suggest that the swimming behavior of fish aggregations passing close to artificial reefs near the seabed displayed a slower moving pattern than fish floating just above the reef structure in the midwater column.

An Experimental Study of Settlement Behavior of Artificial Reef according to Reinforcement Characteristics (해저 연약지반 보강 조건에 따른 인공어초 침하 거동에 대한 실험적 연구)

  • Yun, Dae-Ho;Kim, Yun-Tae
    • Journal of the Korean Geosynthetics Society
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    • v.16 no.1
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    • pp.53-61
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    • 2017
  • Seabed settlement and erosion sometimes occurr when a artificial reef is installed in soft seabed. Therefore, this study carried out CBR test and water tank settlement test to investigate settlement behavior of artificial reef according to reinforcement characteristics such as reinforced types and reinforced area. Soil types of ground are sand, silt and clay deposits. Three reinforced types were prepared: unreinforced, geogrid and hybrid bamboo mat(HBM) with different reinforced area. Laboratory test results indicated that reinforced artificial reef improved bearing capacity of ground and reduced settlement as reinforced area increased. Especially, reinforced HBM provided more bearing capacity and less settlement than reinforced geogrid.

Pore flow Characteristics in Seabed around Dike Due to Variation of Ground Water Level (지하수위 변화에 따른 호안 주변 지반내의 흐름특성)

  • Kim, Chang-Hoon;Kim, Do-Sam;Hur, Dong-Soo
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.19 no.5
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    • pp.408-417
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    • 2007
  • Recently, an artificial beach has been constructed compensating for loss of the natural one caused by the development of coastal area, as well as serving as a location for recreational activities such as sea bathing. It is well known that some structure should be constructed to protect an artificial beach from the outflow due to wave action of the reclaimed sand. In general, dike is utilized as the structure to protect an artificial beach. And, one of the factors which may need to be taken into consideration for stability of dike on seabed foundation is the ground water behavior behind dike. However, the interrelated phenomena of nonlinear wave and ground water response have relatively little attention although these interactions are important for stability of structure and sand suction to the artificial beach. In this paper, the numerical wave tank was developed to clarify nonlinear wave, dike and ground water dynamic interaction, which can simulate the difference of ground water and mean water level. Using the developed numerical wave tank, the present study investigates how variation of ground water level influences hydrodynamic characteristics in seabed around dike and numerically simulates the wave fields, pore flow patterns, pore water pressures and vorticities according to variation of ground water level. Numerical results explain well how hydrodynamic characteristics in seabed around dike is affected by the variation of ground water level.

The application of GIS in analyzing acoustical and multidimensional data related to artificial reefs ground (인공어초 어장에서 수록한 음향학적 다차원 데이터 해석을 위한 GIS의 응용)

  • Kang, Myoung-Hee;Nakamura, Takeshi;Hamano, Akira
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.47 no.3
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    • pp.222-233
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    • 2011
  • This study is for the multi-dimensional analysis of diverse data sets for artificial reefs off the coast of Shimonoseki, Yamaguchi prefecture, Japan. Various data sets recorded in artificial reefs ground were integrated in new GIS software: to reveal the relationships between water temperature and fish schools; to visualize the quantitative connection between the reefs and the fish schools; and to compare the seabed types derived from two different data sources. The results obtained suggest that the application of GIS in analyzing multi-dimensional data is a better way to understand the characteristics of fish schools and environmental information around artificial reefs and particularly in the evaluation of the effectiveness of artificial reefs.

Evaluation of Similarity of Water Column Properties and Sinking Particles between Impact and Preserved Sites for Environmental Impact Assessment in the Korea Contracted Area for Manganese Nodule Development, NE Pacific (북동태평양 한국 망간단괴 광구해역에서 환경충격 시험지역과 보존지역간의 수층환경 및 침강입자 플럭스 유사성 비교)

  • Son, Juwon;Kim, Kyeong Hong;Kim, Hyung Jeek;Ju, Se-Jong;Yoo, Chan Min
    • Ocean and Polar Research
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    • v.36 no.4
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    • pp.423-435
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    • 2014
  • Verifying the similarity of environmental characteristics between an artificial impact site and a preserved or reference site is necessary to quantitatively and qualitatively evaluate the environmental impact of mining activity. Although an impact site (BIS station) and a preserved site (called KOMO station) that have been selected in the Korea manganese nodule contract area may share similar environmental characteristics, similarities in terms of the water column environment between both sites has not been investigated. In this study, we compared the chemical properties of the water columns and sinking particle fluxes between BIS and KOMO stations through two observations (August 2011 and September 2012). Additionally, we observed particle fluxes at the KOMO station for five years (July 2003~July 2008) to understand long-term natural variability. Vertical distributions of water column properties such as dissolved oxygen, inorganic nutrients (N, P, Si), total organic carbon below surface layer (within the depth range of 200 m) were not considerably different between the two sites. Especially, values of water column parameters in the abyssopelagic zone from 4000 m to bottom layer (~5000 m) were very similar between the BIS and KOMO sites. Sinking particle fluxes from the two sites also showed similar seasonality. However, natural variation of particle flux at the KOMO site varied from 3.5 to $129.9mg\;m^{-2}day^{-1}$, with a distinct temporal variation originating from ENSO events (almost forty times higher than a minimum value). These results could provide valuable information to more exactly evaluate the environmental impact of mining activity on water columns.

Performance Test for the Manganese Nodule Crushing Equipment of the Deep Seabed Mining Robot 'MineRo' (심해저 채광로봇 'MineRo' 망간단괴 파쇄 성능시험)

  • Sung, Ki-Young;Min, Cheon-Hong;Kim, Hyung-Woo;Lee, Chang-Ho;Oh, Jae-Won;Hong, Sup
    • Ocean and Polar Research
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    • v.36 no.4
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    • pp.455-463
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    • 2014
  • This paper presents data from performance tests carried out to assess a manganese nodule crusher. Manganese nodules should be crushed into smaller pieces in order to assure the slurry flow of the lifting system. Both artificial nodules and real manganese nodules are used to evaluate nodule breaking ability of the crusher. The crushing performance of the crusher depends on the flow rate and pressure of the power transmission device. The size of the crushed manganese nodules also depends on the shape of the crushing drum. In this paper, several comparative tests are carried out to evaluate and improve the crushing performance and find the optimal design point of the crusher.

An Experimental Study on Settlement Reduction of Artificial Reef using Geosynthetics (토목섬유를 이용한 인공어초 침하 저감에 대한 실험 연구)

  • Ha, Yong-Soo;Kim, Yun-Tae
    • Journal of the Korean Geosynthetics Society
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    • v.14 no.3
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    • pp.21-29
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    • 2015
  • An artificial reef is a human-made underwater structure to improve marine environment and to provide a habitat for fish and other ocean wildlife. An artificial reef is placed on the ocean ground. In soft ground like most of the seabed soil, the ground has been settled due to weight of artificial reef. This study investigated the bearing capacity and settlement reduction effect of geosynthetics which were reinforced on the ground in a large size tank. Penetration tests and large soil tank laboratory tests were performed to investigate settlement reduction effect and bearing capacity on artificial reef with different spreading area of geogrid. Laboratory test results indicate that the spreaded geogrid under artificial reef reduce the settlement of ground and increase bearing capacity of ground.

Scour Characteristics of Artificial Reef through Experiment and Numerical Analysis (실내실험 및 수치해석을 이용한 인공어초 세굴 거동 특성 연구)

  • Yun, Daeho;Kim, Yuntae
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.3
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    • pp.23-32
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    • 2019
  • This study investigated the scour characteristics of artificial reef according to unreinforced and reinforced artificial reefs through laboratory test and numerical analysis. In this study, geogrid was used as a reinforcement of seabed. Three different reinforced areas were selected; one time, three times and five times bottom area of artificial reef. Two-dimensional water channel test was carried out to investigate scour patten of sand and silt grounds. Numerical analysis was also performed to see the velocity vector and scouring patten around artificial reef which was same condition with experiment. The numerical results were in good agreements with the experimental test results. It was found that the geogrid-installed soft ground under artificial reef tends to reduce scour, compared to unreinforced soft ground.

Behaviors of Artificial Reef Reinforced with Settlement Reduction Reinforcement (침하 저감용 보강재로 보강된 인공어초 설치 지반의 거동 특성)

  • Yun, Daeho;Kim, Yuntae
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.1
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    • pp.1-9
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    • 2019
  • This study investigated settlement and scouring characteristics of artificial reef reinforced with various reinforcement types to reduce settlement and scouring. Three reinforcement types were prepared: geogrid, geogrid-bamboo mat (GBM) and seaweed-pile mat (SPM). Various laboratory tests such as bearing capacity test, large size settlement test, two-dimensional flow scour test were performed according to different soil types (sand, silt, clay). Laboratory test results indicated that bearing capacity of seabed with a reinforced artificial reef increased and its settlement and scour depth reduced for all reinforcement types. Especially, reinforcement effect tends to be greater in clay soft ground rather than sand and silt grounds.