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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
Journal Basic Information
Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 24, Issue 6 - Dec 2010
Volume 24, Issue 5 - Oct 2010
Volume 24, Issue 4 - Aug 2010
Volume 24, Issue 3 - Jun 2010
Volume 24, Issue 2 - Apr 2010
Volume 24, Issue 1 - Feb 2010
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Expansion Spool Design of an Offshore Pipeline by the Slope Deflection Method
Choi, Han-Suk ; Do, Chang-Ho ; Na, Young-Jang ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 1~7
Offshore, sub-sea pipelines that transport oil and gas experience thermal expansion induced by the temperature of the transported medium during operation. The expansion of the pipeline can induce overload and cause damage to offshore platforms or sub-sea structures that are connected to the pipelines. To mitigate and prevent these incidents, expansion spools are installed between offshore, sub-sea pipelines and risers on the platform. This paper presents the results of the study and development of a simplified design method for expansion spools, using the slope deflection method for the purpose of preliminary design or front-end engineering and design (FEED).
Flow Structures Around a Freely-falling, Rectangular Cylinder
Jeon, Chung-Ho ; Lee, Chang-Yeol ; Yoon, Hyun-Sik ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 8~15
The flow around a two-dimensional, rectangular cylinder that is freely falling in a channel was simulated using the immersed boundary method with direct forcing to determine the interactions between the fluid and the structure. The results of the present study were in good agreement with previous experimental results. Regardless of the H/L ratio (where H and L are the height and width of the rectangular cylinder, respectively), the flow structures had essentially the same pattern as the two symmetrical circulations that form about the horizontal center of the cylinder, with those centers located at each lateral position near the wake. When the cylinder approaches very close to the bottom, a jet-like flow appeared between the bottom of the rectangular cylinder and the channel. When the jet-like flow goes through the channel, surrounding fluids are sucked into this jet, forming the secondary vortices.
The Effects of Sloshing on the Responses of an LNG Carrier Moored in a Side-by-side Configuration with an Offshore Plant
Lee, Seung-Jae ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 16~21
During the loading/offloading operation of a liquefied natural gas carrier (LNGC) that is moored in a side-by-side configuration with an offshore plant, sloshing that occurs due to the partially filled LNG tank and the interactive effect between the two floating bodies are important factors that affect safety and operability. Therefore, a time-domain software program, called CHARM3D, was developed to consider the interactions between sloshing and the motion of a floating body, as well as the interactions between multiple bodies using the potential-viscous hybrid method. For the simulation of a floating body in the time domain, hydrodynamic coefficients and wave forces were calculated in the frequency domain using the 3D radiation/diffraction panel program based on potential theory. The calculated values were used for the simulation of a floating body in the time domain by convolution integrals. The liquid sloshing in the inner tanks is solved by the 3D-FDM Navier-Stokes solver that includes the consideration of free-surface non-linearity through the SURF scheme. The computed sloshing forces and moments were fed into the time integration of the ship's motion, and the updated motion was, in turn, used as the excitation force for liquid sloshing, which is repeated for the ensuing time steps. For comparison, a sloshing motion coupled analysis program based on linear potential theory in the frequency domain was developed. The computer programs that were developed were applied to the side-by-side offloading operation between the offshore plant and the LNGC. The frequency-domain results reproduced the coupling effects qualitatively, but, in general, the peaks were over-predicted compared to experimental and time-domain results. The interactive effects between the sloshing liquid and the motion of the vessel can be intensified further in the case of multiple floating bodies.
Study of Heat Transfer and Safety Evaluation for Heating Coils in the Fuel Tank of a Ship
Moon, Jin-Gwon ; Park, Jong-Chun ; Kwon, Yoo-Hong ; Yoo, Won-Seok ; Ahn, Soo-Whan ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 22~30
The fuel tank of a ship is filled with heavy fuel oil (HFO) that has a very high viscosity. In order to inject the HFO into the engine easily, heating coils are usually installed inside the fuel tank to heat the HFO and lower its viscosity. Currently, several different types of heating coils are used, e.g., fin-type, bare-type, drum-type, and shell-and-tube-type. It is well known that the shell-and-tube-type heating coil has good performance and high efficiency. In this study, experiments were conducted to determine the heat transfer efficiencies of three different shell-and-tube-type heating coils. Heat transfer efficiency was evaluated by using FLUENT 6.3.26 software. Also, structural safety was assessed by using ANSYS.simulation software.
Particle-based Simulation for Sloshing in a Rectangular Tank
Hwang, Sung-Chul ; Lee, Byung-Hyuk ; Park, Jong-Chun ; Sung, Hong-Gun ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 31~38
The Floating storage and re-gasification unit (FSRU), which has large cargo storage tanks, is a floating liquefied natural gas (LNG) import terminal. The sloshing motion in tanks that are partially filled with LNG can cause impact pressure on the containment system and affect the global motion of the FSRU. Therefore, the accurate prediction of sloshing motion has been a significant issue in the offshore gas production industry. In this paper, a particle method based on the moving particle semi-implicit (MPS) method proposed by Koshizuka and Oka (1996) has been modified to predict sloshing motion accurately in a rectangular tank with the filling ratio of water. The simulation results, including the violent sloshing of the fluid, were validated by comparison with the original MPS method.
Dynamic Analysis of Gravity Quay Wall Considering Development of Excess Pore Pressure in Backfill Soil
Ryu, Moo-Sung ; Hwang, Jai-Ik ; Kim, Sung-Ryul ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 39~47
In this paper, a total stress analysis method for gravity quay walls is suggested. The method can evaluate the displacement of the quay walls considering the effect of excess pore pressure developed in backfill soils. This method changes the stiffness of backfill soils according to the expected magnitude of the excess pore pressure. For practical application, evaluation methods are suggested for determining the excess pore pressure ratio developed in the backfill soils and the backfill stiffness that corresponds to the excess pore pressure ratio. This method is important in practical applications because the displacement of the quay walls can be evaluated by using only the basic input properties in the total stress analysis. The applicability of the suggested method was verified by comparing the results of the analysis with the results of 1-g shaking table tests. From the comparison, it was found that the calculated displacements from the suggested method showed good agreement with the measured displacements of the quay walls. It was also found that the excess pore pressure in backfill soils is a governing influence on the dynamic behavior of quay walls.
Lifetime Seismic Risk of Offshore Structures with a Built-in Vibration Control Device
Kim, Dong-Hyawn ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 48~54
The analysis of the seismic risk of an offshore structure with a control device is presented. First, a probability density function was developed to represent seismic hazard, and seismic fragility under artificial earthquake conditions was determined. Fragility curves for an offshore structure with both passive and active control devices were determined. Displacement criteria were set to evaluate the performance of the structure. Based on numerical analysis, the seismic risk to the structure was considerably reduced when the structure had a seismic control device. The seismic risk to the actively controlled structure was decreased by 80% compared to the uncontrolled case. Reasonable performance evaluations of offshore structure with control devices can be conducted through risk analysis.
Study of Corrosion Resistance in Super-Duplex, Tungsten-Containing Stainless Steel
Choi, Han-Gul ; Park, Hyung-Gyun ; Jung, Byung-Ho ; Han, Hyun-Sung ; Bae, Dong-Su ; Kang, Chang-Yong ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 55~59
The effect of aging on the precipitation of the
phase and corrosion resistance in W-substituted, super-duplex stainless steel was investigated. The volume fraction of the
phase and the current density increased as the aging temperature increased up to
, and, then, they decreased. As aging time increased, the volume fraction of the
phase and the current density also increased. The
phase considerably influenced to corrosion resistance. When Mo was substituted for W in super-duplex stainless steel, the volume fraction of the
phase and the current density both decreased markedly.
Evaluation of the Corrosion Resistance of Zn-Coated Steel as a Function of the Temperature of the Cr-free Solution Used to Coat the Steel
Seo, Hyun-Soo ; Moon, Hee-Joon ; Kim, Jong-Soon ; Ahn, Seok-Hwan ; Moon, Chang-Kwon ; Nam, Ki-Woo ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 60~66
Zinc has a number of characteristics that make it well suited for use as a coating to protecting iron and steel products from corrosion. Its excellent corrosion resistance in most environments accounts for its successful use as a protective coating on a variety of products and in many exposure conditions. The excellent field performance of zinc coatings results from their ability to form dense, adherent films that corrode at a rate that ranges from 1% to 10% of the corrosion rate of ferrous materials, depending on the environment. Recently, EU RoHS and EU ELV prohibited the use of materials that adversely affect the environment, such as Pb, Hg, Cd, and
. In this study, environmentally-friendly, Cr-free solutions (epoxy solution, acrylic solution, and urethane solution S-700) and organic/inorganic solution with Si; LRO-317) were used to evaluate the corrosion resistance of zinc-coated steel subjected to a saltwater spray for 72 hours. The coating of urethane solution (S-700) was best among the three kinds of solution with heat treatment during five minutes at
. Test specimens with S-700 and LRO-317 coating were heat treated in a drying oven at 170, 180, 190, 200, and
for five minutes. The results show that the optimum corrosion resistance was
in EGI and
in HDGI, respectively.
Evaluation of the Corrosion Resistance of Steel Coated with Zinc Using a Cr-free Coating Solution as a Function of Heat Treatment Time
Seo, Hyun-Soo ; Moon, Hee-Joon ; Kim, Jong-Soon ; Ahn, Seok-Hwan ; Moon, Chang-Kwon ; Nam, Ki-Woo ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 67~74
Chromate conversion coating is a coating technique used to passivate aluminum, zinc, cadmium, copper, silver, magnesium, tin, and their alloys to slow corrosion. The process uses various toxic chromium compounds, which may include hexavalent chromium. The industry is developing less toxic alternatives in order to comply with substance restriction legislation, such as RoHS. One alternative is to develop a Cr-free coating solution. In this study, eco-friendly, Cr-free solutions (urethane solution S-700, organic/inorganic solution with Si LRO-317) were used. Test specimens were dried in a drying oven at
for 3, 5, 7, and 9 minutes. Corrosion resistance was evaluated using a salt spray test for 72 hours. The results show that the optimum corrosion resistance was achieved at
for five minutes for EGI and three or five minutes for HDGI, respectively. The adhesive properties of the two types of coating solutions were superior regardless of drying time.
A Study of the Mechanical Properties of Fiberglass Reinforcements with Constitution of Lay-up, Manufacturing Method, and Resins
Song, Ha-Cheol ; Yum, Jae-Seon ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 75~80
Fiberglass-Reinforced Plastic (FRP) composites have been used for small fishing boats and leisure boats for many years. These composites have different physical characteristics, depending on the constitution of lay-up and manufacturing method. Recently, new manufacturing methods, such as vacuum infusion, have been used to make the composites lighter and stronger. In this research, the mechanical properties of fiberglass reinforcements with constitution of lay-up, manufacturing method, and two different resins were investigated experimentally. It was found that the mechanical properties of FRP composites increased with increasing thickness, with the use of vacuum infusion method, and with the use of vinyl ester resin. The mechanical properties of diverse FRP composites can be used as a practical guide for selecting appropriate materials for specific applications.
Analyses of the Maximum Response of Cylinders-Connected Protector under Anchor Colliding and Dragging
Woo, Jin-Ho ; Na, Won-Bae ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 81~87
This study presents the results of collision and lift analyses of a cylinders-connected protector under stock anchor colliding and dragging. For the analyses, the terminal velocity of the stock anchor was obtained first, and, then, the velocity was used to calculate the falling distance of the stock anchor in air. In addition, two other falling distances were considered for purposes of comparison. From the finite element analyses, using ANSYS, the maximum responses obtained from the stock anchor colliding and dragging were obtained and compared for different collision distances (3, 5, and 8.83 m) and dragging angles (0, 30, 60,
). Then, the maximum displacements and stresses were discussed, along with the strength and dimensions of the protector. Finally, conclusions were made for the maximum responses.
A Study on the Structural Analysis of Curved Portions of Pipe Loops Used in Ships
Park, Chi-Mo ; Bae, Byoung-Il ;
Journal of Ocean Engineering and Technology, volume 24, issue 5, 2010, Pages 88~93
Many pipes that are arranged longitudinally in ships have loops at intervals to prevent the failure of the pipes as they absorb large portions of the axial load caused by the bending of the hull girder and/or thermal loads when the pipes are carrying very hot fluids. Since the loops are curved at corners, an efficient method for conducting the structural analyses of these curved portions is required. In this paper, a pipe loop was analyzed by an analytical method and by the finite-element method in four different ways, i.e., based on straight-beam elements, curved-beam elements, 2-D shell elements, and 3-D solid elements. The results of the five analyses were compared to check the validity of the current curved-beam theory. The paper includes some suggestions on how to analyze the pipe loops efficiently.