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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 28, Issue 6 - Dec 2014
Volume 28, Issue 5 - Oct 2014
Volume 28, Issue 4 - Aug 2014
Volume 28, Issue 3 - Jun 2014
Volume 28, Issue 2 - Apr 2014
Volume 28, Issue 1 - Feb 2014
Selecting the target year
Development of WMLS-based Particle Simulation Method for Solving Free-Surface Flow
Nam, Jung-Woo ; Park, Jong-Chun ; Park, Ji-In ; Hwang, Sung-Chul ; Heo, Jae-Kyung ; Jeong, Se-Min ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 93~101
DOI : 10.5574/KSOE.2014.28.2.093
In general, particle simulation methods such as the MPS(Moving Particle Simulation) or SPH(Smoothed Particle Hydrodynamics) methods have some serious drawbacks for pressure solutions. The pressure field shows spurious high fluctuations both temporally and spatially. It is well known that pressure fluctuation primarily occurs because of the numerical approximation of the partial differential operators. The MPS and SPH methods employ a pre-defined kernel function in the approximation of the gradient and Laplacian operators. Because this kernel function is constructed artificially, an accurate solution cannot be guaranteed, especially when the distribution of particles is irregular. In this paper, we propose a particle simulation method based on the moving least-square technique for solving the partial differential operators using a Taylor-series expansion. The developed method was applied to the hydro-static pressure and dam-broken problems to validate it.
Experimental and Numerical Study on Towing Stability of Transportation Barge
Nam, Bo Woo ; Hong, Sa Young ; Kim, Jin Ha ; Choi, Sung Kwon ; Kim, Jong-Wook ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 102~110
DOI : 10.5574/KSOE.2014.28.2.102
This paper presents the results of an experimental and numerical study on the towing characteristics of a barge. A series of model tests were carried out at the Ocean Engineering Basin of KRISO. A model with a 1:50 scale ratio was constructed out of wood. First, force coefficient tests were performed in order to obtain the surge, sway, and yaw force coefficients of the barge. The focus was the effect of skeg on the force coefficients. The stability parameter was calculated from the force coefficients. Next, towing tests in calm sea were carried out with different towline lengths and towing speeds. The trajectories of the barge and the towline tensions were measured during the tests. The measured trajectories were compared with numerical simulation results using a cross-flow model. The towing stability of the barge in a calm sea is discussed in detail.
Agitation Performance Study of 2-shafts Agitator Rotate Directio in the Mud Tank Based on CFD
Im, Hyo-Nam ; Lee, Hee-Woong ; Lee, In-Su ; Choi, Jae-Woong ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 111~118
DOI : 10.5574/KSOE.2014.28.2.111
In drilling process of oil wells, the drilling fluid such as mud keeps the drill bit cool and clean during drilling, with suspending drill cuttings and lubricating a drill bit. In this paper, a commercial CFD package(ANSYS Fluent 15.0) was used to solve the hydrodynamic force and evaluate mud mixing time in the mud mixing tank on offshore drilling platforms. Prediction of power consumption in co-rotating and counter-rotating models has been compared with results of Nagata's correlation equation. This research shows the hydrodynamic effect inside the two phase mud mixing tank according to rotating directions(co-rotating and counter-rotating). These results, we can conclude that the co-rotating direction of the two shafts with mixing blade in the mud mixing tank can be a preferable in power consumption and mixing time reduction.
Experimental Study on Hydrodynamic Coefficients of Autonomous Underwater Glider Using Vertical Planar Motion Mechanism Test
Jung, Jin-Woo ; Jeong, Jae-Hun ; Kim, In-Gyu ; Lee, Seung-Keon ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 119~125
DOI : 10.5574/KSOE.2014.28.2.119
A vertical planar motion mechanism(VPMM) test was used to increase the prediction accuracy for the maneuverability of an underwater glider model. To improve the accuracy of the linear hydrodynamic coefficients, the analysis techniques of a pure heave test and pure pitch test were developed and confirmed. In this study, the added mass and damping coefficient were measured using a VPMM test. The VPMM equipment provided pure heaving and pitching motions to the underwater glider model and acquired the forces and moments using load cells. As a result, the hydrodynamic coefficients of the underwater glider could be acquired after a Fourier analysis of the forces and moments. Finally, a motion control simulation was performed for the glider control system, and the results are presented.
Structural Safety Assessment of Mark III Membrane Type Liquid Natural Gas Cargo Containment System under Ice Collision
Nho, In Sik ; Yun, Young-Min ; Park, Man-Je ; Oh, Young-Taek ; Kim, Sung-Chan ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 126~132
DOI : 10.5574/KSOE.2014.28.2.126
In this study, a method for analyzing the collision and interaction between ice bergy bits and a Mark III type liquid natural gas (LNG) carrier was considered, and the structural safety of a ship's hull and cargo containment system (CCS) was evaluated. In the analysis, a constitutive model implementing the strain rate dependant mechanical property was used to consider the typical material characteristics of ice rationally. A relatively simple and easy ice structure interaction analysis procedure, compared with the accurate but complicated FSI analysis scheme, was suggested. When the ice bergy bits collided with ship's side hull under the four assumed scenarios, the structural behaviors of the ship structure and LNG CCS were simulated by applying the suggested ice collision analysis procedure using the commercial hydro-code LS-DYNA. In addition, the effects of the shapes and colliding speed of the ice bergy bits on the ice-structure interaction and safety of the CCS were examined in detail.
Evaluation of Accumulated Axial Plastic Strain of Sands under Long-term Cyclic Loading
Seo, Min-Chang ; Lee, Si-Hoon ; Kim, Sung-Ryul ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 133~139
DOI : 10.5574/KSOE.2014.28.2.133
Offshore wind turbines have been constructed extensively throughout the world. These turbines are subjected to approximately
horizontal load cycles produced from wind, waves, and current during their lifetimes. Therefore, the accumulated displacement of the foundation under horizontal cyclic loading has significant effects on the foundation design of a wind turbine. Akili(2006) and Achmus et al.(2009) performed cyclic triaxial tests on dry sands and proposed an empirical model for predicting the accumulated plastic strain of sands under long-term cyclic loading. In this study, cyclic triaxial tests were performed to analyze the cyclic loading behaviors of dry sands. A total of 27 test cases were performed by varying three parameters: the relative density of the sands, cyclic load level, and confining stress. The test results showed that the accumulated plastic strain increased with an increase in the cyclic load level and a decrease in the relative density of the sand. The confining stress had less effect on the plastic strain. In addition, the plastic strain at the 1st loading cycle was about 57% of the accumulated strain at 1,000 cycles. Finally, the input parameters of the empirical models of Akili(2006) and Achmus et al.(2009) were evaluated by using the relative density of the sand and the cyclic load level.
Engineering Characteristics of Non-sintering Binder-stabilized Mixture using Industrial By-Products
Yun, Dae-Ho ; Mun, Kyoung-Ju ; Kim, Yun-Tae ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 140~146
DOI : 10.5574/KSOE.2014.28.2.140
This study investigated the engineering characteristics of non-sintering binder-stabilized mixtures consisting of different ratios of a hardening agent(3%, 6%, 9%, 12%) for recycling industrial by-products through several series of laboratory tests. The hardening agents consisted of two kinds of non-sintering binders(NSB-1, NSB-2), which were developed by using inter-chemical reactions among blast furnace slag, phospho-gypsum, and an alkali activator. In addition, ordinary Portland cement(OPC) was used to compare the engineering characteristics of the stabilized mixture. An unconfined compressive test showed that the unconfined compressive strength increased with the curing time and mixing ratio. Experimental test results indicated that the 7-day strength of the NSB-1 mixture was similar to that of the OPC mixture. However, its 28-day strength was higher than that of the OPC mixture. The secant module of elasticity showed a range of
regardless of the agents. Based on the results of triaxial tests, the cohesion and friction angle increased with the mixing ratio.
Structural Design of Multi-Megawatt Wind Turbine Blade by Classical Lamination Theory
Bae, Sung-Youl ; Kim, Bum-Suk ; Lee, Sang-Lae ; Kim, Woo-June ; Kim, Yun-Hae ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 147~151
DOI : 10.5574/KSOE.2014.28.2.147
This research presents a method for the initial structural design of a multi-megawatt wind turbine blade. The structural data for a 2-MW blade were applied as the blade structural characteristic data of the reference blade. Tenkinds of blade models were newly designed by replacing the spar cap axial GRRP with a GFRP and CFRP These terms should be defined. at different orientations. The axial stiffness coefficients of the newly designed models were made equal to the coefficient of the reference blade. The required numbers of layers in each section of blades were calculated, and the lay-up designs were based on these numbers. Verification results showed that the design method that used the structural data of the reference blade was appropriate for the initial structural design of a wind turbine blade.
Study of Deepsea Mining Robot "MineRo" Using Table of Orthogonal Arrays
Lee, Chang-Ho ; Kim, Hyung-Woo ; Choi, Jong-Su ; Yeu, Tae-Kyeong ; Lee, Min-Uk ; Oh, Jae-Won ; Hong, Sup ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 152~159
DOI : 10.5574/KSOE.2014.28.2.152
KRISO(Korea Research Institute of Ships & Ocean Engineering) designed and manufactured a pilot mining robot called "MineRo" in 2012. MineRo is composed of four track modules. In general, much time and money are needed for deep-sea tests. Therefore, a numerical analysis to predict the dynamic behaviors has to be performed before a deep-sea test. In the numerical analysis, the information about the mining robot and soil properties are the most important factors to analyze the driving performance and dynamic response of MineRo. A terra-mechanics model of extremely cohesive soft soil is implemented in the form of the relationships between the normal pressure and sinkage, and between the shear stress and shear displacement. It is possible to acquire information about MineRo from the CAD model in the design phase. The Wong model is applied to the terra-mechanics model. This model is necessary to acquire many soil coefficients for a numerical analysis. However, in soil testing, the amount of soil property data obtained is limited. Moreover, it is difficult to analyze all of the cases for the many soil coefficients. In this paper, the dynamic behaviors of MineRo are analyzed according to the driving velocity, steering ratio, and variable extremely cohesive soft soil properties using a table of orthogonal arrays. The dynamic responses of MineRo are the turning radius, sinkage, and slip ratio. The relationships between the dynamic responses and variable soil properties are derived for MineRo.
Sensitivity Analysis of Design Parameters for Quadruple Offset Butterfly Valve by Operating Torque
Lee, Dong-Myung ; Kim, Soo-Young ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 160~166
DOI : 10.5574/KSOE.2014.28.2.160
Because of industrial development, industrial facilities are becoming more complex and diversified. Plant industries are focused on productivity improvement, cost reduction, and product uniformity by simplifying production processes using automated control. Furthermore, plant industries require higher pressures and temperatures to improve energy efficiency. For this reason, the valves used in plants are operated under harsh conditions. Globe valves and gate valves are mainly used for high pressure these days. However, these valves have various problems, including low maintainability and high cost, due to structural problems. Therefore, butterfly and ball valve applications are increasing in industrial plants. This paper suggests a quadruple-offset butterfly valve that is applicable to bi-direction use, and the principle design parameters are suggested. The selected design parameters are an eccentric flange center line and shaft centerline(Offset 1), an eccentric seat centerline and disc shaft centerline(Offset 2), the angle between the flange centerline and seat wedge angle(Offset 3), the angle between the vertical direction of the disc shaft centerline and seat centerline(Offset 4), and the seat engagement angle. To analyze the interaction effect of the design parameters, ANOM and ANOVA were performed with an orthogonal array. The parameters were found to have effects in the following order: Offset 2, Offset 1, engagement angle, Offset 3, and Offset 4. The interaction between the parameters was insignificant.
Study on Optimum Curve Driving of Four-row Tracked Vehicle in Soft Ground using Multi-body Dynamics
Oh, Jae-Won ; Lee, Chang-Ho ; Hong, Sup ; Bae, Dae-Sung ; Lim, Jun-Hyun ; Kim, Hyung-Woo ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 167~176
DOI : 10.5574/KSOE.2014.28.2.167
This paper proposes an optimum curve driving method for adeep-seabed mining robot(MineRo) in deep-sea soft ground. MineRo was designed as afour-row tracked vehicle. A study on the turning methods for the four-row tracked vehicle was conducted using three case by changing the velocity profile of each track. The configuration of the four-row tracked vehicle and soft ground equation are introduced, along with the dynamics analysis models of MineRo and soft ground, which were constructed using the commercial software DAFUL. Because the purpose of this study was to investigate a driving method on soft ground, the marine environment of the deep sea was not considered.
Analysis on Spray Pattern of Airless Tip for Heavy Duty Coating Using Particle Image Velocimetry
Yoon, Soon-Hyun ; Choi, Hyo-Sung ; Kim, Dong-Keon ; Kim, Bong-Hwan ; Cho, Seung-Wan ;
Journal of Ocean Engineering and Technology, volume 28, issue 2, 2014, Pages 177~184
DOI : 10.5574/KSOE.2014.28.2.177
Heavy duty coating is playing an important role in the field of heavy industry in the development of the shipbuilding and plant industries. Heavy duty coating has the very important function of protecting steel under serious corrosive conditions. The airless tip used for heavy duty coating is an essential part that determines the spray pattern of the paint. This research investigated the injection properties of three airless tips(numbers 521, 523, and 525) by using particle image velocimetry(PIV). The velocity and turbulent intensity according to pressure change with each tip type were investigated by using PIV. If the pressure is greater, the turbulent intensity becomes stronger and the break up of particles becomes bigger as the tip number gets smaller. The velocity is the fastest in the center and decreases in the radial direction.