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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
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Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 27, Issue 6 - Dec 2013
Volume 27, Issue 5 - Oct 2013
Volume 27, Issue 4 - Aug 2013
Volume 27, Issue 3 - Jun 2013
Volume 27, Issue 2 - Apr 2013
Volume 27, Issue 1 - Feb 2013
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Experimental and Numerical Study on Slamming Impact
Kwon, Sun Hong ; Yang, Young Jun ; Lee, Hee Sung ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 1~8
DOI : 10.5574/KSOE.2013.27.1.001
This paper presents the results of experimental and numerical research on the slamming phenomenon. Two experimental techniques were proposed in this study. The traditional free drop tests were carried out. However, the free drop tests done in this study using an LM guide showed excellent repeatability, unlike those of other researchers. The coefficients of variation for the drop test done in this experiment were less than 0.1. The other experimental technique proposed in this study was a novel concept that used a pneumatic cylinder. The pneumatic cylinder could accelerate the specimen over a very short distance from the free surface. As a result, high rates of repeatability were achieved. In the numerical study, the development of in-house code and utilization of commercial code were carried out. The in-house code developed was based on the boundary element method. It is a potential code. This was mostly applied to the computation of the wedge entry problem. The commercial code utilized was FLUENT. Most of the previous slamming research was done under the assumption of a constant body velocity all through the impact process, which is not realistic at all. However, the interaction of a fluid and body were taken into account by employing a user-defined function in this study. The experimental and numerical results were compared. The in-house code based on BEM showed better agreement than that of the FLUENT computation when it cames to the wedge computation. However, the FLUENT proved that it could deal with a very complex geometry while BEM could not. The proposed experimental and numerical procedures were shown to be very promising tools for dealing with slamming problems.
Evaluation of Mating Dynamic Forces of Semi-submersible Offshore Structure Topside Module
Lee, Jin-Ho ; Jung, Hyun-Soo ; Kim, Byung-Woo ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 9~15
DOI : 10.5574/KSOE.2013.27.1.009
This paper calculates the mating dynamic forces of a semi-submersible offshore structure's topside module, where a hull moored in the sea is combined with a topside module carried by a heavy lift vessel, as a mating installation method. The environmental conditions include various wave directions and wave heights, with constant wind and current speeds. Appropriate ballast and de-ballast plans for the heavy lift vessel and hull of the semi-rig should be performed in order to safely obtain these forces, whereas a fixed platform or the GBS (Gravity based structure) type of offshore structure only needs a ballast plan for the heavy lift vessel. From this paper, the allowable wave height or wave direction for the mating procedure can be investigated based on the standard DAF (Dynamic amplitude factor) of the rules and regulations.
Attenuation Characterization of L(0,2) Guided Wave Mode through Numerical Analyses and Model Experiments with Buried Steel Pipe
Lee, Juwon ; Na, Won-Bae ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 16~23
DOI : 10.5574/KSOE.2013.27.1.016
By carrying out numerical analyses and model experiments, this paper presents the attenuation characterization of an L(0,2) guided ultrasonic wave propagating in a buried steel pipe. From this investigation, we first find that the L(0,2) mode has a better attenuation property. Second, it is shown from the numerical analyses that the attenuation increases with increases in the soil embedment length (0, 500, 1000, and 1500 mm) and degrees of saturation (0, 50, 99, and 100%). Third, it is also shown from the model experiment that the attenuation increases as the embedment lengths and soil moisture quantities (0, 10, 20, and 30 kg) increase. Finally, we find that an exponential extrapolation gives a better attenuation prediction because the extrapolation gives similar attenuation patterns between the numerical and experimental results.
Study on Automation for Verification of Naval Ship's Operational Scenarios using Simulation: Focusing on Crew Messroom Case
Oh, Dae-Kyun ; Lee, Dong-Kun ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 24~30
DOI : 10.5574/KSOE.2013.27.1.024
The Korea Navy has been making constant efforts to apply M&S (modeling and simulation) to naval ship development, and the generalization of M&S for ship development is a trend. M&S for ship design is used for the V&V (verification and validation) of its design and operation, including design verification and ergonomic design that considers the crew using the Naval Ship Product Model. In addition, many parts of this M&S are repeatedly accomplished regardless of the kinds of ships. This study aims to standardize M&S, which repeatedly applies similar verifications for operation scenarios. A congestion assessment simulation for the major spaces of ships was the subject of the standardization based on the leading research results of various researchers, and a simulation automation solution was suggested. An information model using XML was proposed through the simulation automation concept, and a prototype system based on it was implemented. The usability was shown through a case study that verified the operability performance of the crew messroom.
Propulsion by Oscillating Foil Attached to Ship in Waves
Choi, Yoon-Rak ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 31~36
DOI : 10.5574/KSOE.2013.27.1.031
In this paper, the effects of a foil attached to a ship on the ship motion, added resistance, and thrust generation in waves are analyzed. The unsteady theory for a two-dimensional foil is introduced to determine the coupled motion responses of the ship and foil. The thrust caused by the oscillating foil is evaluated and compared to the added resistance of the ship, so that a positive net thrust can be possible in waves. A comparison of the results of unsteady, quasi-steady, and experimental analyses is performed.
Fatigue Crack Growth Properties of Friction Stir Welded Dissimilar Aluminum Alloys
Lee, Won-Jun ; Lee, Hyo-Jae ; Kim, Hyung-Jin ; Park, Won-Jo ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 37~42
DOI : 10.5574/KSOE.2013.27.1.037
The presence of a crack can increase the local stress or strain, which can cause inelastic deformation and significantly reduce the life of a component or structure. Therefore, in this study, the fatigue crack growth (FCG) behaviors of friction stir welded Al 2024-T3 and Al 7075-T6 specimens were examined, with fatigue cracks growing parallel to the dynamically recrystallized zone at variable
values and an R ratio of 0.3. In addition, the FCG values of the base metal Al 2024-T3 and Al 7075-T6 were tested under the same conditions and parameters as comparative groups. The results showed that compared with the base metal Al 2024 specimen, which had the best fatigue property, the welded specimen had only 88% of the fatigue cycles.
Structural Safety Evaluation of Marine Loading Arm Using Finite Element Analysis
Song, Chang Yong ; Choi, Ha Young ; Shim, Seung Hwan ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 43~50
DOI : 10.5574/KSOE.2013.27.1.043
This paper presents a structural design review of a marine loading arm used for the fluid transfer of a liquid cargo from a ship or offshore plant. The marine loading arm is installed on a ship, offshore plant, or jetty in order to load or unload liquid cargo such as crude oil, liquefied natural gas (LNG), chemical products, etc. The structural design of this marine loading arm is obliged to comply with the design and construction specifications regulated by the oil companies and international marine forum (OCIMF). In this paper, the structural safety of the initial design for the marine loading arm is evaluated for the design load conditions required by various operational modes. The evaluated results based on a finite element analysis (FEA) are reviewed in relation to the OCIMF specifications.
Study on Conceptual Design of Pressure Vessel to Transport CNG and CO
Kim, Young-Hun ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 51~58
DOI : 10.5574/KSOE.2013.27.1.051
Recently, there has been an increase in the demand for natural gas as a source of clean energy, which has increased the demand for LNG carriers. However, LNG carriers require a capital investment to obtain equipment for the regasification process, which prevents fires and explosions. Thus, on account of NIMBY, a CNG carrier is suggested that eliminates the need for regasification equipment. Meanwhile, carbon dioxide emissions are more and more regulated by international conventions such as the Kyoto Protocol. Because of this,
carriers have also received international attention as a methodology to transport and store
cargoes. Several vessels or tanks to transport and store
gas have been studied in various countries. This paper proposes a conceptual design for a 20ft container shaped tank to effectively transport small cargoes of
and CNG. The proposed pressure vessel or tank will be carried by a conventional containership or special cargo ship. The influences of the design parameters for proposed pressure vessel or tank. Including the materials, scantlings, and shape of the pressure vessel, are studied theoretically and computationally.
Capacity of Horizontally Loaded Suction Anchor Installed in Silty Sand
Kim, Surin ; Choo, Yun Wook ; Kim, Dong-Soo ; Sung, Hong Gun ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 59~66
DOI : 10.5574/KSOE.2013.27.1.059
A suction anchor is one of the most popular anchors for deepsea floating systems. An anchor used for catenary mooring is predominantly under a horizontal load. In this study, the behavior of a suction anchor installed in cohesionless soil was investigated when the anchor was mainly subjected to a horizontal load induced by a catenary line. In order to study the behavior of the suction anchor, 3D FEM analysis models were developed and analyzed. Depending on the location of the load (padeye), the ultimate horizontal load was monitored. The distributions of the reaction forces around the anchor induced by the seabed were analyzed using the circumferential stress to understand the behavior of the suction anchor under a horizontal load.
Numerical Simulation of Towing Stability of Barges in Calm Water
Nam, Bo Woo ; Park, Ji Young ; Hong, Sa Young ; Sung, Hong Gun ; Kim, Jong-Wook ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 67~73
DOI : 10.5574/KSOE.2013.27.1.067
This paper presents the results of a numerical study on the towing stability of barges. Towing simulations were carried out by using two different numerical models (MMG model and cross-flow model). Stability criteria are also suggested based on the analysis of the linearized governing equations for towed vessel motion. In order to validate the present numerical models, the experimental data of Yasukawa et al. (2006) were used. Simulations were conducted for single and double barges under constant towing speed and direction conditions. The time histories of the heading angle, yaw rate, and towline tension were compared between the numerical results and experiments. The effects of the towline length on the slewing frequency and maximum heading angle were also observed. In addition, a series of numerical simulations using variable hydrodynamic coefficients were performed to investigate the effects of the hydrodynamic forces on the towing stability.
Study on Cryogenic Behavior of Reinforced Polyurethane Foam for Membrane Type LNG Carrier
Jang, Cheol-Woong ; Shim, Chun-Sik ; Song, Ha-Cheol ; Song, Chang Yong ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 74~79
DOI : 10.5574/KSOE.2013.27.1.074
In the context of the structural performance of an LNG hold, the mechanical characteristics of the insulation material are considered to be a critical design factor under cryogenic temperatures. This paper presents the thermal elasto-plastic behavior of the reinforced polyurethane foam (RPUF) adapted for the insulation material of a membrane-type LNG carrier via both experiments and numerical simulations realizing the cryogenic condition. The experiments are carried out to investigate the thermal transfer and thermal elasto-plastic deformation characteristics of an actual RPUF specimen. The heat transfer simulations based on the finite element method (FEM) include a forced convection analysis. The results of heat transfer analyses are compared with the experimental results. Reasonable cryogenic conditions for RPUF are reviewed based on both the analysis and experimental results.
Development of Simplified Formulae for Added Mass of a 2-D Floating Body with a Semi-Circle Section in a Finite Water Depth
Koo, Weoncheol ; Kim, Jun-Dong ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 80~84
DOI : 10.5574/KSOE.2013.27.1.080
This study is to develop the simplified formulae for added mass coefficient of a 2-D floating body with a semi-circle section in a finite water depth. The semi-circle floating body may represent a simplified midship section transformed by Lewis form, which can be used for the ship motion analysis by strip theory. Since the added mass coefficient varies with motion frequencies and sea bottom effect, the correction factor representing the effect of water depth and frequencies is developed for accurate prediction of added mass. Using a two-dimensional numerical wave tank (NWT) technique based on the boundary element method (BEM) including sea bottom boundary the reference values of added mass are calculated to develop the correction factor. For verification and effectiveness of the formulae, the predicted added mass coefficients for various frequencies and water depth ratios are compared with the calculated values from NWT technique.
Power Estimation and Optimum Design of a Buoy for the Resonant Type Wave Energy Converter Using Approximation Scheme
Koh, Hyeok-Jun ; Ruy, Won-Sun ; Cho, Il-Hyoung ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 85~92
DOI : 10.5574/KSOE.2013.27.1.085
This paper deals with the resonant type of a WEC (wave energy converter) and the determination method of its geometric parameters which were obtained to construct the robust and optimal structure, respectively. In detail, the optimization problem is formulated with the constraints composed of the response surfaces which stand for the resonance period(heave, pitch) and the meta center height of the buoy. Use of a signal-to-noise ratio calculated from normalized multi-objective results with the weight factor can help to select the robust design level. In order to get the sample data set, the motion responses of the power buoy were analyzed using the BEM (boundary element method)-based commercial code. Also, the optimization result is compared with a robust design for a feasibility study. Finally, the power efficiency of the WEC with the optimum design variables is estimated as the captured wave ratio resulting from absorbed power which mainly related to PTO (power take off) damping. It could be said that the resultant of the WEC design is the economical optimal design which satisfy the given constraints.
Mitigation Effects of Incident Bore Impact Loads Acting on a Tall Structure by Installation of Obstacles
Lee, Byung-Hyuk ; Hwang, Sung-Chul ; Park, Jong-Chun ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 93~101
DOI : 10.5574/KSOE.2013.27.1.093
The incident bore impact loads acting on a tall structure is simulated using the refined Moving Particle Simulation (MPS) method. The particle method is more feasible and effective than conventional grid-based methods for the violent free-surface problems. In the present study, the simulation results for the temporal change of the hydrodynamic force on the structure and longitudinal velocity component around the structure are compared with the experiments (Radd and Bidoae, 2005). And the mitigation effects by installation of various obstacles in front of the main structure are investigated and discussed form the simulation results.
On the Statistical Characteristics of the New Year Wave
Kim, Do Young ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 102~108
DOI : 10.5574/KSOE.2013.27.1.102
In this paper time series wave data, which were measured at the Draupner platform in the North Sea on 1995, are used to investigate statistical characteristics of nonlinear wave. Various statistical properties based on time and frequency domain are examined. The Gram-Chalier distribution fits the probability of wave elevation better than the Gaussian distribution. The skewness of wave profile is 0.393 and the kurtosis is 4.037 when the freak wave is occurred. The nonlinearity of D1520 data is higher than two adjacent wave data. AI index of the New Year Wave is 2.11 and the wave height is 25.6m. The zero crossing wave period of the New Year Wave is 12.5s which is compared to the average zero up-crossing period 11.3s. The significant steepness of wave data is 0.077 when the freak wave was occurred. H1/3/
does not increases as the kurtosis increases and the values is close to 4. The New Year Wave belongs to highly nonlinear wave data packet but the AI index is within linear focusing range.
Analysis on Temperature Change of Super Changer for the Reduction of Auto Exhausts Gas
Lee, Jong-Ho ; Kim, Sung-Won ; Yoon, Han-Ki ;
Journal of Ocean Engineering and Technology, volume 27, issue 1, 2013, Pages 109~114
DOI : 10.5574/KSOE.2013.27.1.109
Regulations on exhaust emissions for vehicles and ships are reinforced. Therefore, researchers are focus on developing an excellent engine that emits less environmental pollutants and leads to high gas milage. The purpose of this study is to investigate the efficiency of intake super charging system. Super charger is the special device for improving performance of intake system. Futhermore, for reducing exhaust emissions, the examine are performed on the effectiveness of device structures that tow materials for performance improvement. To fulfill the purpose, Super charger materials of aluminum alloy(AL6262) and polycarbonate were selected and then their temperature change of super charger and inhalation efficiency were analyzed by ANSYS program. In addition, it is attempted to apply these results to device development by comparing the results with the real value. As a result, there was less temperature change of super charger in aluminum materials than polycarbonate, and HC and NOx were decreased when the super charger was installed.