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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 23, Issue 6 - Dec 2009
Volume 23, Issue 5 - Oct 2009
Volume 23, Issue 4 - Aug 2009
Volume 23, Issue 3 - Jun 2009
Volume 23, Issue 2 - Apr 2009
Volume 23, Issue 1 - Feb 2009
Selecting the target year
Effect on the Residual Stress of Cure Profiles, Fillers and Mold Constraints in an Epoxy System
Moon, Chang-Kwon ; Nam, Ki-Woo ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 1~5
A dilatometer was used to investigate the effect of cure conditions, mold types and the presence of filler in an epoxy system. These studies showed shrinkage in the cured epoxy when heating it through the glass transition temperature region. The magnitude of the shrinkage, related to stress build up in the epoxy during curing, was influenced by the processing conditions, filler presence and the nature of the mold used to contain the resin. Cure and cyclic cure at a lower temperature, prior to a post cure, decreased the magnitude of observed shrinkage. Cure shrinkage decreased with the number of cyclic cures. Post cured samples outside the mold led to less shrinkage compared with samples in the mold. Sample cured in a silicon mold represented less shrinkage than sample cured in an aluminum mold. Sample containing kaolin filler showed less shrinkage than unfilled sample.
Numerical Analysis of Internal Waves in Two-layer Fluids by a Two-domain Boundary Element Method
Koo, Weon-Cheol ; Kim, Mi-Geun ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 6~11
In this study, the internal waves in two-density layered fluids were analyzed using the Numerical Wave Tank (NWT) technique in the frequency domain. The NWT is based on a two-domain Boundary Element Method with the potential fluids using the whole-domain matrix scheme. From the mathematical solution of the two-domain boundary integral equation, two different wave modes could be classified: a surface wave mode and an internal wave mode, and each mode were shown to have a wave number determined by a respective dispersion relation. The magnitudes of the internal waves against surface waves were investigated for various fluid densities and water depths. The calculated results are compared with available theoretical data.
An Experimental Study on Compressibility Effect in Sloshing Phenomenon
Park, Jun-Soo ; Kim, Hyun-Yi ; Lee, Ki-Hyun ; Kwon, Sun-Hong ; Jeon, Soo-Sung ; Jung, Byoung-Hoon ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 12~18
The present study focused on the compressibility of partially filled fluids in a sloshing tank. Filling ratios ranging from 18% to 26% were used to find compressible impact on a vertical wall. The model test was for 1/25 scale of a 138 K LNGC cargo tank. To investigate the two dimensional phenomenon of sloshing, a longitudinal slice model was tested. A high speed camera was used to capture the flow field, as well as the air pocket deformation. The pressure time history synchronized with the video images revealed the entire compressible process. Three typical impact phenomena were observed: hydraulic jump, flip through, and plunging breaker. In particular, the pressure time history and flow pattern details for flip through and plunging breaker are presented.
Variation in Vegetation Area caused by Topographical Change at Jinudo in the Nakdong Estuary
Ryu, Sung-Hoon ; Lee, In-Cheol ; Park, So-Young ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 19~24
In order to analysis the variation in vegetation area caused by topographical change at Jinudo in the Nakdong estuary, we used aerial photographs of Jinudo from 1998 to 2006. To extract an accuracy shoreline from these aerial photographs, a tide calibration was performed. We also estimated the annual variation in topographic area and vegetation area, and then analyzed the relationship between them by a correlation analysis. The following results were obtained: 1) The calibrated shoreline distance of Jinudo from 1998 to 2006 was estimated to have a range of (-)1,927 cm to (+)4,671 cm. 2) Annual changes in the topographic area and vegetation area in Jinudo have been increasing gradually from 1998, and the correlation coefficient between topographic area and vegetation area is 0.97. 3) The estimated topographic areas were with following order: southern (III), eastern (IV), northern (II) and western (I), while for the vegetation area, the order was southern (III), northern (II), eastern (IV) and western (I). 4) The vegetation area of the southern region (III) of Jinudo had the largest size among the regions, and was calculated to be
times larger than the eastern region (IV).
A Numerical Prediction of Pollutant Material Budget during the Flood and Dry Season in Gwangyang Bay
Kim, Jin-Hyuk ; Lee, In-Cheol ; Yoon, Han-Sam ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 25~31
To predict pollutants during the flood and dry season in Gwangyang Bay, the net-fluxes and pollutant material budgets of COD, T-N, and T-P were calculated in Gwangyang Bay using a 2-D hydrodynamic model. Calculating the net-flux for each area in Gwangyang Bay showed that the net-fluxes in regions IV, V, and VII were increasing, but those of regions II, III, and VI were decreasing. In budget calculations for COD, T-N, and T-P in Gwangyang Bay, it was estimated that during the dry season the COD is approximately 1.6 times higher than during the flood season. The T-N during the flood season is approximately 7 times higher than during the dry season. However, the material budget for T-P in Gwangyang Bay predicted that it is almost nonexistent. Moreover, the central part of Gwangyang Bay (Region IV) has the highest material budget of overall pollutants.
An Analytic Analysis for a Two-Dimensional Floating and Fluid-Filled Membrane Structure
Choi, Yoon-Rak ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 32~37
An analytic similarity shape solution was studied for a two-dimensional floating and fluid-filled membrane structure. The static shape of a membrane structure can be expressed as a set of nonlinear ordinary differential equations. The integration of curvature leads to an analytic solution for the shape, which contains unknown boundary values. Matching the upper and lower shapes at the free surface incorporated with their buoyancy allowed the unknowns to be determined. Some characteristic values of similarity shapes were evaluated and shapes are illustrated for various density ratios and volume efficiency ratios.
Flow Analysis around a High-speed Planing Hull Model
Kim, Byoung-Nam ; Kim, Wu-Joan ; Yoo, Jae-Hoon ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 38~46
Two sets of numerical simulations were carried out for a planing hull model ship. In the first, the WAVIS 1.4 linear and nonlinear potential solver was utilized with the free support condition, in which the running posture was determined during calculation. The linear and nonlinear potential calculation results showed qualitative agreement in the trim and resistance coefficient with the MOERI towing tank test. However, the nonlinear potential calculation gave better results than the linear method. In the next simulation, Fluent 6.3.26 with a VOF model and the WAVIS 1.4 nonlinear potential solver were used with the given running posture from the measurement carried out in the MOERI towing tank. Fluent with the VOF method had substantially better agreement with model test results than the results from the WAVIS nonlinear potential calculation for the total resistance coefficient, and for the bow and stern wave patterns, in spite of the much greater computational costs. Both methods can be utilized in planing hull design when their limitations are perceived, and the running posture should be predicted correctly.
An Estimation Technique for the Thrust Performance of AUVs
Lee, Chong-Moo ; Choi, Hyun-Taek ; Moon, Il-Sung ; Lee, Pan-Mook ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 47~51
Thrust is one of the important performance characteristics of an AUV. At the design stage, the resistance of an AUV at its maximum speed is estimated and then the thrust system is designed, including the propeller diameter, propeller rpm, driving system, and required power. However, it is not possible to be certain that the thrust system has been correctly designed until the AUV is launched and its speed is measured. If data from a propeller open-water test is available, the thrust and torque of the propeller at a certain speed can be estimated. In addition, if the motor's torque characteristics are available, the maximum speed saturated by the induced propeller torque can be estimated. In this paper, an easy technique for estimating the maximum speed of an AUV will be shown, even in a case where additional resistance is gained from appendages not considered at the design stage. Furthermore, the thrust performance changes by adjusting the diameter of the propeller can be easily investigated.
The Effect of Aging Treatment on the Microstructure and Mechanical Properties of Super Duplex Stainless Steel with W
Kim, Soo-Chun ; Bae, Dong-Soo ; Kang, Chang-Yong ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 52~57
The effect of aging treatment on the microstructure and mechanical properties of super duplex stainless steel with W was investigated. The phase was precipitated mainly at the early stage of aging and a lower aging temperature under
, but the phase was formed after long-term aging treatment between
. The volume fraction of the phase increased with aging temperature up to
and then decreased up to
. With an increase in the aging time, the volume fraction phase at the early stage of aging increased slightly, and then increased rapidly beyond a certain time. The rapid increase in the tensile strength and hardness and decrease in the elongation and impact toughness were measured with aging temperatures up to
. On the other hand, the tensile strength and hardness decreased slightly, and the elongation and Charpy impact toughness were unchanged with aging temperatures over
. The tensile strength and hardness increased rapidly at the early stage of aging, and then increased slowly beyond a certain time. The elongation and Charpy impact toughness decreased rapidly at the early stage of aging, and then remained unchanged beyond a certain time. The phase that formed at the early stage of aging and the lower aging temperature had a considerable effect on the elongation and Charpy impact toughness of the super duplex stainless steel with W.
Electrochemical Evaluation of Corrosion Property of Welding Zone of 304 Stainless Steel
Moon, Kyung-Man ; Kim, Yun-Hae ; Kim, Jong-Do ; Lee, Myung-Hoon ; Kim, Jin-Gyeong ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 58~63
Two kinds of welding methods are used for austenitic 304 stainless steel: laser welding and TIG welding. The difference in the corrosion characteristics of the welded zone between these two welding methods was investigated using electrochemical methods, such as corrosion potential measurements, polarization curves, cyclic voltammograms, etc. The Vickers hardnesses of all the welded zones (WM: Weld Metal, HAZ: Heat Affected Zone, BM: Base Metal) showed relatively higher values in the case of laser welding than for TIG welding. Furthermore, the corrosion current densities of all the welding zones showed lower values compared to TIG welding. In particular, the corrosion current density of the HAZ with TIG welding had the highest value of all the welding zones, which suggests that chromium depletion due to the formation of chromium carbide appears in the HAZ, which is in the range of the sensitization temperature. Thus, it can easily be corroded with a more active anode. Consequently, we found that the corrosion resistance of all of the welding zones for austenitic 304 stainless steel could apparently be improved by using Laser welding.
Evaluation of Corrosion Resistance of Anti-Corrosive Paint by Investigation of Diffusion Limiting Current Density
Moon, Kyung-Man ; Kim, Yun-Hae ; Lee, Myung-Hoon ; Lee, In-Won ; Park, Hyun ; Chun, Ho-Hwan ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 64~68
It has been observed that coated steel structures deteriorate more rapidly than the designed lifetime due to acid rain caused by air pollution, etc. Therefore, improving the corrosion resistance of anti-corrosive paint is very important in terms of safety and the economic point of view. In this study, the corrosion resistance of five kinds of anti-corrosive paints, including the Acryl, Fluorine, and Epoxy resin series, were investigated with electrochemical methods, such as corrosion potential measurements, polarization curves, diffusion limiting current density, etc. As a result, the corrosion resistance of the F101 specimen with the fluorine resin series was found to be superior to the other specimens, while E100 with the epoxy resin series also showed a somewhat good corrosion resistance. Furthermore, it was observed that the amount of water and oxygen entering the inner side of a painted film increased with an increase in immersion time, irrespective of the kind of resin series. However, the oxygen diffusion limiting current density of a specimen with good corrosion resistance was relatively decreased compared to other specimens, because of the difficulty of oxygen diffusion penetrating to the inner side of the film. Consequently it is suggested that we can qualitatively evaluate the corrosion resistance of an anti-corrosive paint by measuring the diffusion limiting current density as an electrochemical method.
Structural Analysis of S-cam Brake Shoe for Commercial Vehicle by FEM
Suh, Chang-Min ; Jee, Hyun-Chul ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 69~77
Structural analysis of a brake shoe for commercial vehicle was performed using finite element method. Since the strength of a brake shoe is affected by the magnitude and distribution shape of the contact pressure with the drum, the contact pressure between the shoe friction material and drum was calculated using a 2-Dimensional non-linear contact analysis in a state. And the brake was actuated by input air pressure and the drum of it was calculated both stationary and dynamic based on forced torque applied to the drum during the static state analysis. The results of the above analysis were then used as the load boundary conditions for a 3-Dimensional shoe model analysis to determine the maximum strain on the shoes. In the analysis model, the values of tensile test were used for the material properties of the brake shoes and drum, while the values of compression test were used for the friction material. We assumed it as linear variation, even though the properties of friction material were actually non-linear. The experiments were carried out under the same analysis conditions used for fatigue test and under the same brake system which equipped with a brake drum based on the actual axle state in a vehicle. The strains were measured at the same locations where the analysis was performed on the shoes. The obtained results of the experiment matched well with those from the analysis. Consequently, the model used in this study was able to determine the stress at the maximum air pressure at the braking system, thereby a modified shoe model in facilitating was satisfied with the required endurance strength in the vehicle.
Development of Integrated Operating Program for Inshore Test Miner and its Simulator
Lee, Do-Kyoung ; Yoon, Suk-Min ; Park, Soung-Jea ; Yeu, Tae-Kyeong ; Hong, Sup ; Kim, Hak-Kyeong ; Kim, Sang-Bong ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 78~84
This paper presents development results of integrated operating program and its simulator for an inshore test miner. The inshore test miner drives on the seabed and collects manganese nodules. For operating the test miner, integrated operating program (IOP) is needed for remote control and monitor of the miner in real-time. However, it is hard to develop the practical IOP for the test miner system, because the system is big, expensive, and unique. So a simulator was developed as a test substitute in order to save time and to reduce cost. Using test results of the simulator, the IOP of the test miner was developed. The developed IOP consists of remote program, host program, monitoring program and database program. The operating program was developed using PXI and Labview of NI. The experimental results are presented to show the applicability of the developed program.
Dispersion Effect of Hydration Heat in Mass Concrete Using Embedded Heat Pipe
Kim, Myung-Sik ; Youm, Chi-Sun ; Baek, Dong-Il ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 85~90
Although most of existing hydration heat control methods show a certain degree of hydration heat control, generally, there are many problems as mentioned above. Therefore, our laboratory previously developed a hydration heat control method using an exposed heat pipe, which solves most of these problems and simultaneously displays excellent hydration heat control. Unfortunately, even this method had some problems such as the processing, transport, and assembly of heat pipes, and the surface treatment of a cut plane after pouring, and hardening concrete. Therefore, in this study, a hydration heat control method using an embedded pipe has been developed with the expectation that this method solves those problems in hydration heat control using an exposed heat pipe. As a result of the experiment, the peak temperature of ECHP and ICHP specimen about
than the OPC specimen and the probability of thermal cracked generated in ECHP and ICHP specimen decreased up to
. Finally, it was confirmed in this study that the hydration heat control method using an embedded heat pipe is significantly more superior and cost effective than the existing method of an exposed one.
Development of Design Formulas for Pipe Loops Used in Ships Considering the Curvature of Corners
Park, Chi-Mo ; Yang, Park-Dal-Chi ;
Journal of Ocean Engineering and Technology, volume 23, issue 4, 2009, Pages 91~99
Many longitudinally arranged pipes in ships are subject to considerable displacement loads caused by the hull girder bending of ships and/or thermal loads in some special pipes through which fluids with highly abnormal temperatures are conveyed. As these loads may cause failure in the pipes or their supporting structures, loops have been widely adopted as a measure to prevent such failure, with the idea that they can lower the stress level in a pipe by absorbing some portion of these loads. But since such loops have some negative effects, such as causing extra manufacturing cost and occupying extra space, the number and dimensions of the loops need to be minimized. This research developed design formulas for pipe loops, modeling them as a spring element, for which the axial stiffness is calculated based on the beam theory, incorporating the effects of the curvature of loop corners and the flexibility of the straight portion of the pipe. The accuracy of the proposed design formulas was verified by comparing two results respectively obtained by the proposed formulas and MSC/NASTRAN. The paper ends with a sample application of the proposed formulas showing their efficiency.