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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 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
Selecting the target year
Study on Operating Performance Estimation Process of Electric Propulsion Systems for 2.5 Displacement Ton Class Catamaran Fishing Boat
Jeong, Yong-Kuk ; Lee, Dong-Kun ; Jeong, Uh-Cheul ; Ryu, Cheol-Ho ; Oh, Dae-Kyun ; Shin, Jong-Gye ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 1~9
DOI : 10.5574/KSOE.2013.27.5.001
Because the environmental regulations for ships are getting tighter, green ships employing eco-friendly technology have recently received a large amount of attention. Among them, various studies for electric propulsion ships have been carried out, particularly in the United States, European Union, and Japan. On the other hand, research related to electric propulsion ships in Korea is in a very nascent stage. In this paper, an estimation process based on the rough requirements of ship-owners for the operating performance of electric propulsion ships is proposed. In addition, the estimation process is applied to a small fishing boat for verification of the process. These results are expected to be used as design guidelines in the early stage of the design process for electric propulsion ships.
Crack-healing Behavior and Corrosion Characteristics of SiC Ceramics
Hwang, Jin Ryang ; Kim, Dae Woong ; Nam, Ki Woo ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 10~15
DOI : 10.5574/KSOE.2013.27.5.010
The crack-healing behavior and corrosion resistance of SiC ceramics were investigated. Heat treatments were carried out from
. A corrosion test of SiC was carried out in acid and alkaline solutions under KSL1607. The results showed that heat treatment in air could significantly increase the strength. The heat-treatment temperature has a profound influence on the extent of crack healing and the degree of strength recovery. The optimum heat-treatment temperature was
for one hour at an atmospheric level. In the two kinds of solutions, the cracks in a specimen were reduced with increasing time, and the surface of the crack healed specimen had a greater number of black and white spots. The strength of the corroded cracked specimen was similar to that of the cracked specimen. The strength of the corroded crack healed specimen decreased 47% and 75% compared to that of the crack healed specimen in the acid and alkaline solutions, respectively. Therefore, the corrosion of SiC ceramics is faster in an alkaline solution than in an acid solution.
Study on Flow Around Circular Cylinder Advancing Beneath Free Surface
Yi, Hyuck-Joon ; Shin, Hyun-Kyung ; Yoon, Bum-Sang ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 16~21
DOI : 10.5574/KSOE.2013.27.5.016
The flow around a circular cylinder advancing beneath the free surface is numerically investigated using a VOF method. The simulations cover Froude numbers in the range of 0.2~0.6 and gap ratios (h/d) in the range of 0.1~2.0, where h is the distance from the free surface to a cylinder, and d is the diameter of a cylinder at Reynolds number 180. It is observed that the vortex suppression effect and surface deformation increase as the gap ratio decreases or the Froude number increases. The most important results of the present study are as follows. The proximity of the free surface causes an initial increase in the Strouhal number and drag coefficient, and the maximum Strouhal number and drag coefficient occur in the range of 0.5~0.7. However, this trend reverses as the gap ratio becomes small, and the lift coefficient increases downward as the gap ratio decreases.
Thermal Shock Properties of 316 Stainless Steel
Lee, Sang-Pill ; Kim, Young-Man ; Min, Byung-Hyun ; Kim, Chang-Ho ; Son, In-Soo ; Lee, Jin-Kyung ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 22~27
DOI : 10.5574/KSOE.2013.27.5.022
The present work dealt with the high temperature thermal shock properties of 316 stainless steels, in conjunction with a detailed analysis of their microstructures. In particular, the effects of the thermal shock temperature difference and thermal shock cycle number on the properties of 316 stainless steels were investigated. A thermal shock test for 316 stainless steel was carried out at thermal shock temperature differences from
. The cyclic thermal shock test for the 316 stainless steel was performed at a thermal shock temperature difference of
up to 100 cycles. The characterization of 316 stainless steels was evaluated using an optical microscope and a three-point bending test. Both the microstructure and flexural strength of 316 stainless steels were affected by the high-temperature thermal shock. The flexural strength of 316 stainless steels gradually increased with an increase in the thermal shock temperature difference, accompanied by a growth in the grain size of the microstructure. However, a thermal shock temperature difference of
produced a decrease in the flexural strength of the 316 stainless steel because of damage to the material surface. The properties of 316 stainless steels greatly depended on the thermal shock cycle number. In other words, the flexural strength of 316 stainless steels decreased with an increase in the thermal shock cycle number, accompanied by a linear growth in the grain size of the microstructure. In particular, the 316 stainless steel had a flexural strength of about 500 MPa at 100 thermal-shock cycles, which corresponded to about 80% of the strength of the as-received materials.
Determination of Nesting Algorithm Fitness Function through Various Numerical Experiments
Lee, Hyebin ; Ruy, WonSun ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 28~35
DOI : 10.5574/KSOE.2013.27.5.028
In this paper, a research on the composition of the nesting algorithm fitness function is carried out by performing various numerical experiments to inspect how it affects the scrap efficiency, allocation characteristics, and time consumption, targeting the nesting results of ship parts. This paper specifically concentrates on a method to minimize the scrap ratio and efficiently use the well-defined remnants of a raw plate after the nesting process for the remnant nesting. Therefore, experiments for various ship parts are carried out with the weighting factor method, one of the multi-objective optimum design methods. Using various weighting factor sets, the nesting results are evaluated in accordance with the above purposes and compared with each set for each ship part groups. Consequently, it is suggested that the nesting algorithm fitness function should be constructed differently depending on the characteristics of the parts and the needs of the users.
Optimum Design of Truss on Sizing and Shape with Natural Frequency Constraints and Harmony Search Algorithm
Kim, Bong-Ik ; Kown, Jung-Hyun ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 36~42
DOI : 10.5574/KSOE.2013.27.5.036
We present the optimum design for the cross-sectional(sizing) and shape optimization of truss structures with natural frequency constraints. The optimum design method used in this paper employs continuous design variables and the Harmony Search Algorithm(HSA). HSA is a meta-heuristic search method for global optimization problems. In this paper, HSA uses the method of random number selection in an update process, along with penalty parameters, to construct the initial harmony memory in order to improve the fitness in the initial and update processes. In examples, 10-bar and 72-bar trusses are optimized for sizing, and 37-bar bridge type truss and 52-bar(like dome) for sizing and shape. Four typical truss optimization examples are employed to demonstrate the availability of HSA for finding the minimum weight optimum truss with multiple natural frequency constraints.
Characteristics of Heaving Motion of Hollow Circular Cylinder
Bae, Yoon Hyeok ; Cho, Il-Hyoung ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 43~50
DOI : 10.5574/KSOE.2013.27.5.043
In the present investigation, the hydrodynamic characteristics of a vertically floating hollow cylinder in regular waves have been studied. The potential theory for solving the diffraction and radiation problem was employed by assuming that the heave response motion was linear. By using the matched eigenfunction expansion method, the characteristics of the exciting forces, hydrodynamic coefficients, and heave motion responses were investigated with various system parameters such as the radius and draft of a hollow cylinder. In the present analytical model, two resonances are identified: the system resonance of a hollow cylinder and the piston-mode resonance in the confined inner fluid region. The piston resonance mode is especially important in the motion response of a hollow circular cylinder. In many cases, the heave response at the piston resonance mode is large, and its resonant frequency can be predicted using the empirical formula of Fukuda (1977). The present design tool can be applied to analyze the motion response of a spar offshore structure with a moon pool.
Water Wave Interactions with Array of Floating Circular Cylinders
Park, Min-Su ; Jeong, Youn-Ju ; You, Young-Jun ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 51~62
DOI : 10.5574/KSOE.2013.27.5.051
The water wave interactions on any three-dimensional structure of arbitrary geometry can be calculated numerically through the use of source distribution or Green`s function techniques. However, such a method can be computationally expensive. In the present study, the water wave interactions in floating circular cylinder arrays were investigated numerically using the eigenfunction expansion method with the three- dimensional potential theory to reduce the computational expense. The wave excitation force, added mass coefficient, radiation damping coefficient, and wave run-up are presented with the water wave interactions in an array of 5 or 9 cylinders. The effects of the number of cylinders and the spacing between them are examined because the water wave interactions in floating circular cylinder arrays are significantly dependent upon these.
Comparison of Fatigue Damage Models of Spread Mooring Line for Floating Type Offshore Plant
Park, Jun-Bum ; Kim, Kookhyun ; Kim, Kyung-Su ; Ko, Dae-Eun ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 63~69
DOI : 10.5574/KSOE.2013.27.5.063
The mooring lines of a floating type offshore plant are known to show wide banded and bimodal responses. These phenomena come from a combination of low and high frequency random load components, which are derived from the drift-restoring motion characteristic and wind- sea, respectively. In this study, fatigue models were applied to predict the fatigue damage of mooring lines under those loads, and the result were compared. For this purpose, seven different fatigue damage prediction models were reviewed, including mathematical formula. A FPSO (floating, production, storage, and offloading) with a
spread catenary mooring system was selected as a numerical model, which was already installed at an offshore area of West Africa. Four load cases with different combinations of wave and wind spectra were considered, and the fatigue damage to each mooring line was estimated. The rain flow fatigue damage for the time process of the mooring tension response was compared with the results estimated by all the fatigue damage prediction models. The results showed that both Benasciutti-Tovo and JB models could most accurately predict wide banded bimodal fatigue damage to a mooring system.
Study on Improvement in Numerical Method for Two-phase Flows Including Surface Tension Effects
Park, Il-Ryong ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 70~76
DOI : 10.5574/KSOE.2013.27.5.070
The present paper proposes a coupled volume-of-fluid (VOF) and level-set (LS) method for simulating incompressible two-phase flows that include surface tension effects. The interface of two fluids and its motion are represented by a VOF method designed using high-resolution differencing schemes. This hybrid method couples the VOF method with an LS distancing algorithm in an explicit way to improve the calculation of the normal and curvature of the interface. It is developed based on a rather simple algorithm to be efficient for various practical applications. The accuracy and convergence properties of the method are verified in a simulation of a single gas bubble rising in a three-dimensional flow with a large density ratio.
Effects of Welding Parameters on Diffusible Hydrogen Contents in FCAW-S Weld Metal
Bang, Kook-Soo ; Park, Chan ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 77~81
DOI : 10.5574/KSOE.2013.27.5.077
The effects of the welding parameters, contact tip-to-workpiece distance (CTWD), current, and voltage on the diffusible hydrogen content in weld metal deposited by self-shielded flux cored arc welding were investigated and rationalized by comparing the amount of heat generated in the extension length of the wire. This showed that as CTWD increased from 15mm to 25mm, the amount of heat generated was increased from 71.1J to 174.8J, and the hydrogen content was decreased from 11.3mL/100g to 5.9mL/100 g. Even if little difference was observed in the amount of heat generated, the hydrogen content was increased with an increase in voltage because of the longer arc length. A regression analysis showed that the regression coefficient of voltage in self-shielded flux cored arc welding is greater than that in
arc welding. This implies that voltage control is more important in self-shielded flux cored arc welding than in
Effects of Ship Speed and Ice Thickness on Local Ice Loads Measured in Arctic Sea
Lee, Tak-Kee ; Lee, Jong-Hyun ; Rim, Chae-Whan ; Choi, Kyungsik ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 82~87
DOI : 10.5574/KSOE.2013.27.5.082
The icebreaking research vessel ARAON conducted her second ice trial in the Arctic Ocean during the summer season of 2010. During this voyage, the local ice loads acting on the bow of the port side were measured using 14 strain gauges. The measurement was carried out during icebreaking while measuring the thickness of the ice every 10 m. The obtained strain data were converted to the equivalent stress values, and the effects of the ship speed and ice thickness on the ice load were investigated. As a result, it was found that a faster speed produced a larger stress, according to the variation in the peak values below an ice thickness condition of 1.5 m. Meanwhile, the effect of the ice thickness on the ice load was not clear.
A Study on Calculation of Local Ice Pressures for ARAON Based on Data Measured at Arctic Sea
Lee, Tak-Kee ; Kim, Tae-Wook ; Rim, Chae Whan ; Kim, Sungchan ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 88~92
DOI : 10.5574/KSOE.2013.27.5.088
The icebreaking research vessel (IBRV) ARAON had her second ice trial in the Arctic Ocean in the summer season of 2010. During the voyage, the local ice loads acting on the bow of the port side were measured using 14 strain gauges. These measurements were carried out in three icebreaking performance tests. To convert the measured strains into the local ice pressures, a finite element model of the instrumented area was developed. The influence coefficient method (ICM), which uses the influence coefficient from the finite element model, and the direct method, which uses the measured strain, were selected as the conversion methods. As a result, the maximum measured pressure was 1.236MPa, and the average difference between ICM and the direct method was about 5% for an area of
. The pressure-area relationship of the measurement falls below the range of the existing pressure-area curve, which is due to the low ice strength of melted ice in the summer.
Electrofusion Joining Technology for Polyethylene Pipes Using Carbon Fiber
Ahn, Seok-Hwan ; Ha, Yoo-Sung ; Moon, Chang-Kwon ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 93~98
DOI : 10.5574/KSOE.2013.27.5.093
Fuel gas is an important energy source that is being increasingly used because of the convenience and clean energy provided. Natural gas is supplied to consumers safely through an underground gas-pipe network made of a polyethylene material. In electrofusion, which is one of the joining methods used, copper wire is used as the heating wire. However, it takes a long time for fusion to occur because the electrical resistance of copper is low. In this study, therefore, electrofusion was conducted by replacing the copper heating wire with carbon fiber to reduce the fusion time and improve the production when joining large pipes. Fusion and tensile tests were performed after the electrofusion joint was made in the polyethylene pipe using carbon fiber. The results showed that the fusion time was shorter and the temperature inside the pipe was higher with an increase in the current value. The ultimate tensile strength of specimens was higher than that of virgin polyethylene pipe, except for polyethylene pipes joined using a current of 0.8 A. The best fusion current value was 0.9 or 1.0 A because of the short fusion time and lack of transformation inside the pipe. Thus, it was shown that carbon fiber can be used to replace the copper heating wire.
A Study on Exothermic Properties of TiO
Ahn, Seok-Hwan ; Ha, Yoo-Sung ; Moon, Chang-Kwon ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 99~104
DOI : 10.5574/KSOE.2013.27.5.099
Recently, various nanoparticles have been used for filler in polymer matrices. The particles of nano size are whether high or not cross-link density in polymer affects the thermal and mechanical properties of one. The properties change as a result of chemical reactions between the nanoparticles and the surface of the polymer. There are two models for nanocomposites: "repulsive interaction" and "attractive interaction" between the nanoparticles and matrix. In this study, the variation in the curing mechanism was examined when nano-size
was dispersed into an epoxy (Bisphenol A, YD-128) with different curing agents. The results of this study showed that the exothermic temperature and Tg in the case of the nanoparticles used (Jeffamine) (D-180) at room temperature were reduced by an increase in the
contents because of the "repulsive interaction" between the nanoparticles and the matrix. The tensile strengths were increased by increasing amounts of
until 3 wt% because of a dispersion strengthening effect caused by the nanoparticles, because of the repulsive interaction. However, such tensile properties decreased at 5 wt% of
, because the
was agglomerated in the epoxy. In contrast, in the case of the nanoparticles that used NMA and BDMA, the exothermic temperature and Tg tended to rise with increasing amounts of
as a result of the "attractive interaction." This was because the same amounts of
were well dispersed in the epoxy. The tensile strength decreased with an increase in the
contents. In the general attractive interaction model, however, the cross-link density was higher, and tensile strength tended to increase. Therefore, for the nanoparticles that used NMA, it was difficult to conclude that the result was caused by the "attractive model."
Dispersion Simulation of Hydrogen in Simple-shaped Offshore Plant
Seok, Jun ; Heo, Jae-Kyung ; Park, Jong-Chun ;
Journal of Ocean Engineering and Technology, volume 27, issue 5, 2013, Pages 105~114
DOI : 10.5574/KSOE.2013.27.5.105
Lots of orders of special vessels and offshore plants for developing the resources in deepwater have been increased in recent. Because the most of accidents on those structures are caused by fire and explosion, many researchers have been investigated quantitatively to predict the cause and effect of fire and explosion based on both experiments and numerical simulations. The first step of the evaluation procedures leading to fire and explosion is to predict the dispersion of flammable or toxic material, in which the released material mixes with surrounding air and be diluted. In particular turbulent mixing, but density differences due to molecular weight or temperature as well as diffusion will contribute to the mixing. In the present paper, the numerical simulation of hydrogen dispersion inside a simple-shaped offshore structure was performed using a commercial CFD program, ANSYS-CFX. The simulated results for concentration of released hydrogen are compared to those of experiment and other simulation in Jordan et al.(2007). As a result, it is seen that the present simulation results are closer to the experiments than other simulation ones. Also it seems that the hydrogen dispersion is closely related to turbulent mixing and the selection of the turbulence model properly is significantly of importance to the reproduction of dispersion phenomena.