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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 22, Issue 6 - Dec 2008
Volume 22, Issue 5 - Oct 2008
Volume 22, Issue 4 - Aug 2008
Volume 22, Issue 3 - Jun 2008
Volume 22, Issue 2 - Apr 2008
Volume 22, Issue 1 - Feb 2008
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Three-Dimensional Numerical Model for Flow with Silt Protector
Hong, Nam-Seeg ; Kim, Ga-Ya ; Kang, Yoon-Koo ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 1~7
In this study, a mathematical model for flaw with silt protector is proposed that adds a second-order energy loss term in the momentum equation. The three-dimensional numerical model was developed based on mathematical models and verified through comparison with flume test results. Loss coefficients were evaluated through the flume tests and applied to the numerical model. It was found through the investigation of various example cases that the downstream flow pattern was affected mainly by penetration of the silt curtain, not by the approach velocity, and also that the blocking effect of velocity was increased by the increase in mesh density of the silt curtain, below a certain mesh density. The blocking effect did not increase further above a certain mesh density.
Inundation Analysis on Coastal Zone around Masan Bay by Typhoon Maemi (No. 0314)
Chun, Jae-Young ; Lee, Kwang-Ho ; Kim, Ji-Min ; Kim, Do-Sam ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 8~17
Wrenching climatic changes due to ecocide and global wanning are producing a natural disaster. Coastal zones have been damaged by typhoons and accompanying storm surges. Severe waves, and destruction of the environment are adding to the severity of coastal disasters. There has been an increased interest in these coastal zone problems, and associated social confusion, after the loss of life and terrible property damage caused by typhoon Maemi. Especially if storm surges coincide with high ticks, the loss of life and property damage due to high waters are even worse. Therefore, it is desirable to accurately forecast not only the timing of storm surges but also the amount water level increase. Such forecasts are very important from the view point of coastal defense. In this study, using a numerical model, storm surge was simulated to examine its fluctuation characteristics for the coastal area behind Masan Bay, Korea. In the numerical model, a moving boundary condition was incorporated to explain wave run-up. Numerically predicted inundation regimes and depths were compared with measurements from a field survey. Comparisons of the numerical results and measured data show a very good correlation. The numerical model adapted in this study is expected to be a useful tool for analysis of storm surges, and for predicting inundation regimes due to coastal flooding by severe water waves.
Numerical Simulation of Internal-External Wave Field Interaction in Permeable Coastal Structures
Cha, Jong-Ho ; Yoon, Han-Sam ; Ryu, Cheong-Ro ; Kang, Yoon-Koo ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 18~23
This study investigated interactions between the internal-external wave field of a permeable coastal structure consisting of rubble. The study examined the application criteria of an existing numerical model (CADMAS-SURF V.4.0) and proposed a modified method to provide reasonable results. In particular, the study focused on and emphasized the water surface profiles in front of a structure, wave run-up/run-down on a slope, and internal water level fluctuations due to the drag coefficient and porosity of a rubble mound structure. In conclusion, the result show that when the vertical fluctuations of the internal water levels in permeable coastal structures exhibited high-quality representation. Sane responses can be seen for wave run-up/run-down characteristics on its slopes.
A Study on Flow and Creation and Dissipation of Vorticity around Rectangular Floating Breakwater
Yoon, Jung-Sung ; Kim, Myoung-Kyu ; Jung, Kwang-Hyo ; Kim, Ga-Ya ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 24~33
In this study, flow and creation and dissipation of vorticity around rectangular floating breakwater is investigated both experimentally and numerically. The PIV system(Particle image velocimetry) is employed to obtain the velocity field in the vorticity of rectangular structure. The numerical model, combined with
turbulence model and the VOF method based on RANS equation, is used to analyze the turbulence structure. In the results of this study, the vorticity is found around conner of rectangular structure at all time domain, and creation and dissipation of vorticity are closely related to wave period. Separation points of phase of vortex due to flow separation for longer period waves are faster then for shorter period waves.
A Study on a Nonlinear Control Algorithm for the Automatic Berthing of Ships
Won, Moon-Cheol ; Hong, Seong-Kuk ; Jung, Yun-Ha ; Kim, Sun-Young ; Son, Nam-Sun ; Yoon, Hyun-Gyu ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 34~40
his study discusses the design of an automatic berthing control algorithm for ships with a haw thruster and a stern thruster, as well as a rudder. A nonlinear mathematical model for the law speed maneuvering of ships was used to design a MIMO (multi-input multi-output) nonlinear control algorithm. The algorithm consists of two parts, the forward velocity control and heading angle control. The control algorithm was designed based on the longitudinal and yaw dynamic models of ships. The desired heading angle was obtained by the so-called "Line of Sight" method. An optimal control force allocation method forthe rudder and the thrusters is suggested. The nonlinear control algorithm was tested by numerical simulations using MATLAB, and showed good tracking performance.
Experimental Vibration Analysis for Viscoelastically Damped Circular Cylindrical Shell Using Nonlinear Least Square Method
Min, Cheon-Hong ; Park, Han-Il ; Bae, Soo-Ryong ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 41~46
It is a recent trend for advanced ships and submarines to incorporate composite structures with viscoelastically damping material. Much research has been done on curve-fitting techniquesto identify vibration characteristic parameters such as natural frequencies, modal damping ratios, and mode shapes of the composite structure. In this study, an advanced technique for accurately determining vibration characteristic of a circular cylindrical shell-attached viscoelastically damping material is used, based on a multi-degree of freedom (MDOF) curve-fitting method. First, an initial value is obtained by using a linear least square method. Next, using the initial value, the exact modal parameters of the composite circular cylindrical shell are obtained by using a nonlinear least square method. Results show computation time is greatly decreased and accurate results are obtained by the MDOF curve-fitting method.
Research into the Development of HLA-based Ship Safety Assessment Simulation with Systems Engineering
Lee, Kyung-Ho ; Han, Young-Soo ; Lee, Byung-Hak ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 47~57
Many accidents occur on the oceans. Accidents involving ships can cause enormous damage. When an accident occurs, the cost of environmental restoration can bankrupt even a top-ranked international company. The potential damages resulting from ship accidents have resulted in many international agreements such as MARPOL, SOLAS, ISM Code, etc. The viability of damaged ships has become more and more important. A damaged ship's viability and cargo safety can be improved by a safety assessment design procedure. We consider th￡ shipbuilding industry's distributed characteristics to define a safety assessment system with software engineering-based requirements analysis. We used a distributed network-based simulation method (HLA - High level architecture), because of ease of reuse and expansion of existing components to other situations, and because it is a military standard. HLA is the standard for distributed network-based simulation in many countries including the United States, Canada, Israel, and Korea. The paper describes research to develop a prototype of a network-based safety assessment simulation system by software engineering based analysis.
Hull Form Development of 32-ft Class Leisure Boat by Statistical Analysis of Actual Ships
Jeong, Uh-Cheul ; Park, Je-Woong ; Kim, Kyu-Sun ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 58~63
A 32-ft class leisure boat was newly developed using statistical analysis of actual ships. Resistance performances were investigated by testing models in a high-speed circulating water channel, and with the CFD method. The effects of a trim tab and of a fin attached at the hull side were studied together. Wave patterns were observed to clarify the relationship between resistance performance and wave characteristics. It was found that a trim tab and a side fin play a role in increasing resistance performance within a certain velocity range.
An Experimental Study for the Mechanical Properties of Model Ice Grown in a Cold Room
Kim, Jung-Hyun ; Choi, Kyung-Sik ; Jeong, Seong-Yeob ; Seo, Young-Kyo ; Cho, Seong-Rak ; Lee, Chun-Ju ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 64~70
A full-scale field experiment is an important part in the design of ships and offshore structures. Full-scale tests in the ice-covered sea, however, are usually very expensive and difficult tasks. Model tests in a refrigerated ice tank may substitute this difficulty of full-scale field tests. One of the major tasks to perform proper model tests in an ice towing tank is to select a realistic material for model ice which shows correct similitude with natural sea ice. This study focuses on the testing material properties and the selection of model ice material which will be used in an ice model basin. The first Korean ice model basin will be constructed at the Maritime & Ocean Engineering Research Institute (MOERI) in 2009. With an application to the MOERI ice model basin, in this study the material properties of EG/AD/S model ice of IOT (Institute for Ocean Technology) Canada, were tested. Through comprehensive bending tests, the elastic modulus and the flexural strength of EG/AD/S model ice were evaluated and the results were compared with published test results from Canada. Instead of using an ice model basin, a cold room facility was used for making a model ice specimen. Since the cold room adopts a different freezing procedure to make model ice, the strength of the model ice specimen differs from the published test results. The reason for this difference is discussed and the future development for a making model ice is recommended.
The Characteristics of Acoustic Emission of
Ceramics by an Amount of Additive
Kim, Jin-Wook ; Ahn, Seok-Hwan ; Nam, Ki-Woo ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 71~75
This paper illustrates haw
contributes to crack-healing strengths as a function of crack-healing temperature and the additive amount. In investigating mechanical properties, the indentation fracture method is very simple and useful, but careful attention must be paid to the statistical data processing because data may be scattered excessively, especially for brittle materials. To estimate accurate AE signal properties we applied the useful time-frequency method with a discrete wavelet analysis algorithm. In experiments, three kinds of specimens were prepared. After the specimens were indented by a Vickers indentor, they were heat-treated and crack-healed to evaluate bending strength and the AE signal. With higher amounts of the additive powder, as 1, 3, or 5% wt. of
, the concentrative tendency of dominant frequency trended toward lower frequency groups. The
ceramic with 3% wt. of
was judged most suitable because it demonstrated superior crack-healing ability and relative concentration on the highest frequency group.
Effect of Cathodic Protection of Adjacent Steel Piles on the Life of Sacrificial Anode
Moon, Kyung-Man ; Lee, Kyu-Hwan ; Cho, Hwang-Rae ; Lee, Myung-Hoon ; Kim, Yun-Hae ; Kim, Jin-Gyeong ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 76~81
There are two cases when the life of a sacrificial anode is shortened from the designed life: one case results from self-corrosion of the anode due to contamination by sea water in the other case, however, electrical current to protect some given steel piles overflows to protect other, adjacent non-protected steel piles. In this study, the variation of polarization potential of nine steel piles, being protected cathodically and with anode-producing current between anode and steel piles, was investigated. Parameters were varied, such as the eighth and ninth steel piles either connected electrically or not, and whether the ninth steel pile was protected by another sacrificial anode or not. The current produced by the sacrificial anode decreased when the ninth steel pile was cathodically protected by the anode of another pile. However, produced current increased when the ninth steel pile was not connected to another anode. The study concludes that the life of a sacrificial anode can be prolonged or shortened depending on whether adjacent steel piles are cathodically protected or not.
An Electrochemical Study on Corrosion Property of Repair Welding Part for Exhaust Valve
Moon, Kyung-Man ; Lee, Kyu-Hwan ; Cho, Hwang-Rae ; Lee, Myung-Hoon ; Kim, Yun-Hae ; Kim, Jin-Gyeong ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 82~88
The diesel engine of the merchant ship has been aperated in severe environments more and more, because the temperature of the exhaust gas of a combustion chamber is getting higher and higher with increasing use of heavy oil of law quality, due to the significant increase in the price of oil in recent some years. As a result, the degree of wear and corrosion between exhaust valve and seat ring is more serious compared to other engine parts. Thus the repair welding of exhaust valve and seat ring is a unique method to prolong the life of the exhaust valve, from an economical point of view. In this study, the corrosion property of both weld metal and base metal was investigated using electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram, and polarization resistance in 5% H2SO4 solution. The test specimen was a part of an exhaust valve stem being welded as the base metal, using various welding methods. In all cases, the corrosion resistance as well as hardness of the weld metal zone was superior to the base metal. In particular, plasma welding showed relatively good properties for both corrosion resistance and hardness, compared to other welding methods. In the case of DC SMAW (Shielded metal arc welding), corrosion resistance of the weld metal zone was better than that of the base metal, although its hardness was almost same as the base metal.
Fatigue Crack Growth Behavior of the Thin-to-Thick Type Stiffened Panels with Bonded Patch
Rhee, Hwan-Woo ; Kim, Seung-Hyun ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 89~95
Fatigue cracked components often needs to be repaired during service. Standard repair schemes involve strengthening the component by connecting reinforcing members by means of rivets or welding by reducing the crack-tip stress intensity factors. Recent technological advances in fiber reinforced composite materials and adhesive bonding have led to the development of efficient repair schemes. In this study, the influence of various shape parameters on fatigue crack growth in the CCT type uniform thickness plates and the thin-ta-thick type stiffened panels repaired with woven fabric type Kevlar-Epoxy composite patch are studied experimentally.
An Experimental Study on the Tensile and Fatigue Strengths of SUS304L Lap Joint Weld at the Cryogenic Temperature
Kim, Kyung-Su ; Boo, Seung-Hwan ; Park, Chang-Youl ; Cho, Young-Gun ; Lee, Jeung-Soo ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 96~102
As LNG tank is operated around
, an experimental approach on the cryogenic temperature tensile and fatigue strengths of SUS304L lap joint weld is very important at the design stage of membrane type LNG tank. In this study, in order to estimate the tensile and fatigue strengths of SUS304L lap joint weld at cryogenic temperature condition, tensile and fatigue tests were conducted. Also, S-N curves are presented with statistical testing method recommended by JSME. As a result of the experimental approach, the d￡sign guide of fatigue strength is proposed and that is expected to be useful for membrane type LNG tank design.
An Experimental Study on Development of Artificial Reefs Using Volcanic Stones for Marine Forests
Hong, Chong-Hyun ; Ghoa, Jong-Hun ;
Journal of Ocean Engineering and Technology, volume 22, issue 3, 2008, Pages 103~108
Topics discussed in this paper are engineering design of artificial reefs, design considerations of compressive strength and pH, materials of silica fume concrete and volcanic stones for reef construction, and field monitoring of artificial reefs. Six artificial reefs were deployed offshore at Biyangdo in July 2006, and succession patterns on the reefs were investigated bimonthly from July 2006 to October 2007. The spore-bag method, which has been widely used in Korea for the attachment of seaweed on artificial reefs, was applied to the developed reefs using the kelp Ecklonia cava, which is the dominant species in Jeju, and recruitment and growth patterns were observed.