• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.6
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• pp.692-710
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• 2018

The Three-dimensional (3-D) dynamical behaviors of a fluid-conveying pipe subjected to vortex-induced vibration are investigated with different internal flow velocity ${\nu}$. The values of the internal flow velocity are considered in both subcritical and supercritical regimes. During the study, the 3-D nonlinear equations are discretized by the Galerkin method and solved by a fourth-order Runge-Kutta method. The results indicate that for a constant internal flow velocity ${\nu}$ in the subcritical regime, the peak Cross-flow (CF) amplitude increases firstly and then decrease accompanied by amplitude jumps with the increase of the external reduced velocity. While two response bands are observed in the In-line (IL) direction. For the dynamics in the lock-in condition, 3-D periodic, quasi-periodic and chaotic vibrations are observed. A variety of CF and IL responses can be detected for different modes with the increase of ${\nu}$. For the cases studied in the supercritical regime, the dynamics shows a great diversity with that in the subcritical regime. Various dynamical responses, which include 3-D periodic, quasi-periodic as well as chaotic motions, are found while both CF and IL responses are coupled while ${\nu}$ is beyond the critical value. Besides, the responses corresponding to different couples of ${\mu}_1$ and ${\mu}_2$ are obviously distinct from each other.

• Economic and Environmental Geology
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• v.31 no.6
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• pp.557-567
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• 1998

In order to utilize the data obtained during the deep-sea resources exploration program, the analysis of data structure and database were conducted to develop an appropriate data operating system called Deep-sea Database System. The Relation Data Base Management System, RDBMS, was chosen as a data managing system and the MS Access$^{TM}$ as a DB engine, and the MapInfo$^{TM}$ software as GIS tools. Problems in networking and security were detected and solved during the operation test. Accordingly, development of standardized operative procedure was proposed in obtaining raw data. This proposal will also be reflected in the subsequent phase of the deep-sea program. The Deep-sea Database System could be applied to the selection of potential mining sites and the estimation of economical efficiency over th KODOS (Korea Deep Ocean Study) region. It is also expected that this system might improve the efficiency of detail survey and help in the relinquishment process as a fulfillment of the obligation as a pioneer investor.

• 한국지구물리탐사학회:학술대회논문집
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• 2011.10a
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• pp.151-152
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• 2011

• 한국지구물리탐사학회:학술대회논문집
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• 2011.10a
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• pp.161-162
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• 2011

• 한국석유지질학회:학술대회논문집
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• autumn
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• pp.34-34
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• 2000

• Journal of the Korean Society of Industry Convergence
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• v.21 no.6
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• pp.389-394
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• 2018

Remotely operated vehicle(ROV) and autonomous underwater vehicle(AUV) have been used for underwater surveys, underwater exploration, resource harvesting, offshore plant maintenance and repair, and underwater construction. It is hard for people to work in the deep sea. Therefore, we need a vision control system of underwater submersible that can replace human eyes. However, many people have difficulty in developing a deep-sea image control system due to the deep sea special environment such as high pressure, brine, waterproofing and communication. In this paper, we will develop an Ethernet based remote image control system that can control the image mounted on ROV.

• Economic and Environmental Geology
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• v.46 no.6
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• pp.569-580
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• 2013

Co-rich ferromanganese crusts (Fe-Mn crusts) distributed on the seamounts in the western Pacific are potential economic resources for cobalt, nickel, platinum, and other rare metals in the future. Regulations for prospecting and exploration of Fe-Mn crusts in the Area, which enables the process to obtain an exclusive exploration right for blocks of the fixed size, were enacted recently by the International Seabed Authority, which led to public attention on its potential for commercial development. Evaluation and selection of a mining site can be established based on abundance and grade of Fe-Mn crusts in the site as well as topography that should be smooth enough for mining efficiency. Therefore, acquisition of shipboard echo-sounding and acoustic backscatter data are prerequisite to select potential mine sites in addition to visual and sampling operations. Acoustic backscatter data can be used to locate crust-covered areas in a regional scale with the understanding of acoustic properties of crust through its correlation with visual and sampling data. KIOST had collected the topographic and geologic data to assess the resources potential for Fe-Mn crusts in the west Pacific region from 1994 to 2001. However, they could not obtain acoustic backscatter data that is crucial for the selection of prospective mining sites. Therefore, additional exploration surveys are required to carry out side scan sonar mapping combined with seafloor observation and sampling to decide the blocks for application of an exclusive exploration right.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.222-230
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• 2016

HEMIRE is a 6,000-meter-class remotely operated vehicle (ROV) that has been developed for observation and sampling of objects of interest on the deep seabed. We first carried out deep-seabed exploration around the slopes of the Hupo Bank and the Ulleung Basin in the East Sea in June 2015. Over two weeks, a total of 10 dives were made from a support ship, the R/V Onnuri, at eight stations with water depth ranging between 194 and 2,080 m. The dive times ranged from 1 to 6 hours, depending on the operating conditions. We obtained the following results: 1) video images of the deep seafloor; 2) red snow crab density data (a major fishery resource) and inventories of deep-sea fauna, including an unrecorded organism; 3) specific topographies such as canyons slopes; 4) an undisturbed sediment core obtained using a push corer; and 5) observations of the seabed surface covered with discarded anthropogenic waste material.

• Geophysics and Geophysical Exploration
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• v.11 no.3
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• pp.167-176
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• 2008

Lau basin of the south Pacific, as an active back arc basin, is promising area bearing seafloor massive hydrothermal deposit that is located in a subduction zone between the Pacific ocean plate and Indo-Australian continental plate. We performed multi-beam bathymetry survey in the Lau basin using EM120, to find out high hydrothermal activity Bone. Fonualei Rift and Spreading Center (FRSC) and Mangatolou Triple Junction (MTJ) area were selected for precise site survey through seafloor morphology investigation. The result of surface and deep-tow magnetometer survey showed that Central Anomaly Magnetization High (CAMH) recorded which is associated with active ridge in FRSC-2 and revealed very low magnetic anomalies that can be connected to past or present high hydrothermal activity in MTJ-1 seamount area. Moreover, the physical and chemical tracers of hydrothermal vent flume, i.e., transmission, hydrogen ion concentration (pH), adenosine triphosphate (ATP), methane (CH4) by use of CTD system, showed significant anomalies in those areas. From positive vent flume results, we could conclude that these areas were or are experiencing very active volcanic activities. The acquired chimney and hydrothermal altered bed rock samples gave us confidence of the existence of massive hydrothermal deposit. Even though not to use visual exploration equipment such as ROV, DTSSS, etc., traditional marine geophysical investigation approach might be a truly cost-effective tool for exploring seafloor hydrothermal massive deposit.

• Ocean Systems Engineering
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• v.8 no.1
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• pp.21-32
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• 2018

Due to the escalation in hydrocarbon consumption, the offshore industry is now looking for advanced technology to be employed for deep sea exploration. Riser system is an integral part of floating structure used for such oil and gas extraction from deep water offering a system of drill twines and production tubing to spread the exploration well towards the ocean bed. Thus, the marine risers need to be precisely employed. The incorporation of the strengthening material, fiber reinforced polymer (FRP) for deep and ultra-deep water riser has drawn extensive curiosity in offshore engineering as it might offer potential weight savings and improved durability. The design for FRP strengthening involves the local design for critical loads along with the global analysis under all possible nonlinearities and imposed loadings such as platform motion, gravity, buoyancy, wave force, hydrostatic pressure, current etc. for computing and evaluating critical situations. Finite element package, ABAQUS/AQUA is the competent tool to analyze the static and dynamic responses under the offshore hydrodynamic loads. The necessities in design and operating conditions are studied. The study includes describing the methodology, procedure of analysis and the local design of composite riser. The responses and fatigue damage characteristics of the risers are explored for the effects of FRP strengthening. A detail assessment on the technical expansion of strengthening riser has been outlined comprising the inquiry on its behavior. The enquiry exemplifies the strengthening of riser as very potential idea and suitable in marine structures to explore oil and gas in deep sea.