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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
Editor in Chief :
Volume & Issues
Volume 19, Issue 6 - Dec 2005
Volume 19, Issue 5 - Oct 2005
Volume 19, Issue 4 - Aug 2005
Volume 19, Issue 3 - Jun 2005
Volume 19, Issue 2 - Apr 2005
Volume 19, Issue 1 - Feb 2005
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Aerodynamic Characteristics of Impulse Turbine with an End Plate for Wave Energy Conversion
HYUN BEOM SOO ; MOON JAE SEUNG ; HONG SEOK WON ; KIM KI SUP ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 1~7
This paper deals with the design and aerodynamic analysis of a special-type impulse turbine, with an end plate for wave energy conversion. Numerical analysis was performed using a CFD code, FLUENT. The main idea of the proposed end plate was to minimize the adverse effect of tip clearance of turbine blade, and was borrowed from ducted propeller, with so-called penetrating end plate for special purpose marine vehicles. Results show that efficiency increases up to
, depending on the flow coefficient; a higher flow coefficient yields increased efficiency. Decrease of input coefficient CAwith an end plate is the main reason for higher efficiency. Performance of end plate at various design parameters, as well as flow conditions, was investigated; the advantages and disadvantages of the presentimpulse turbine were also discussed.
Experimental Study on Wave Overtopping Rate of Wave Overtopping Control Structure for Wave Energy Conversion
Shin, Seung-Ho ; Hong, Key-Yong ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 8~15
Wave energy has been considered to be one of the most promising energy resources for the future, as it is pollution-free and an abundant natural resource. However, since it has drawbacks of non-stationary energy density, it is necessary to change the wave energy into a simple concentrated energy. Progressive waves in a coastal area can be amplified, swashed, and overtopped by a wave overtopping control structure. By conserving the quantity of overflow in a reservoir, the kinetic energy of the waves can be converted to the potential energy with a hydraulic head above the mean sea level. The potential energy in the form of a hydraulic head can be utilized to produce electric power, similar to hydro-electric power generation. This study aims to find the most optimal shape of wave overtopping structure for maximum overtopping volume of sea water; for this purpose, we carried out the wave overtopping experiment in a wave tank, under both regular and irregular wave conditions.
An Analytic Solution to Sloshing Natural Periods for a Prismatic Liquid Cargo Tank with Baffles
Shin, Jang-Ryong ; Choi, Kyung-Sik ; Kang, Sin-Young ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 16~21
In the design of super tankers or LNG carriers, which transport a large amount of liquid in the cargo tanks, the structural d11mage due to liquid sloshing is an important problem. The impact pressure from sloshing is most violent when the liquid motion of a partially filled tank is in resonance with the motion of a ship. In this study, the sloshing natural periods of a baffled tank, often installed to reduce liquid motion, is analyzed. A variational method is adopted to estimate the sloshing natural periods for a prismatic cargo tank with baffles of arbitrary filling depth of liquid; the results are compared with Lloyd's Register regulations on sloshing periods. In this study, using an effective liquid-fill-depth concept, sloshing periods for a baffled tank can be expressed by the same form as rectangular prismatic tanks without baffles. In contrast to Lloyd's Register regulations, which can be applicable only to cargo tanks with constant baffle size and distribution, the present results can be applicable to cases of variable baffle size and distribution.
Patterns of Water Level Increase by Storm Surge and High Waves on Seawall/Quay Wall during Typhoon Maemi
Kang, Yoon-Koo ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 22~28
We investigated the characteristics of the overflow/wave overtopping, induced by the storm surge and high waves in Masan bay and Busan Coast during Typhoon 'Maemi', which landed at the southeast coast of the Korean peninsula on September, of 2003, causing a severe inundation disaster. Characteristics of the water level, increase by the overflow / wave overtopping, were discussed in two patterns. One is the increase of water level in the region, located inside of a bay, like Masan fishing port, and the waves are relatively small. The other is in the open sea, in which the waves act directly, as on the seawall in Suyong bay. In the former region, the water level increase was affected by the storm surge, as well as the long period oscillation and waves. In Masan fishing port, about
of the water level increase on the quay wall was caused by the storm surge. In the latter one, it was greatly affected by the wave run-up. In Suyong bay, about
of the water level increase on the seawall was caused by the wave run-up.
An Experimental Study of Chloride Acceleration on the Seawater Resistance of Fly Ash Antiwashout Underwater Concrete
Kwon, Jung-Hyun ; Kim, Bong-Ik ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 29~34
This paper describes the effect of fly ash replacement on seawater resistance of anti-washout underwater concrete, which was replaced cement by fly ash from
. The experimental work was performed to find out the variations of length and weight of specimens, using a chloride acceleration test in
C The results shaw that the admixture using fly ash on an anti-washcout underwater concrete in the sea environment makes it more durable for the attacks of chloride by seawater. Also, the length of specimens of anti-washout underwater concrete, at age 180 days, increased substantially, compared with normal concrete; however, the mixture in which cement was replaced
of fly ash shows
reduction of the expansion, compared with the normal anti "washout underwater concrete specimen.
Nonlinear Dynamic Responses among Wave, Submerged Breakwater and Seabed
HAN DONG SOO ; KIM CHANG HOON ; YEOM CYEONG SEON ; KIM DO SAM ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 35~43
Recently, various-shaped coastal structures have been studied and developed. Among them, the submerged breakwater became generally known as a more effective structure than other structures, bemuse it not only serves its original function, but also has the ability to preserve the coastal environment. Most previous investigations have been focused on the wave deformation and energy dissipation due to submerged breakwater, but less interest was given to their internal properties and dynamic behavior of the seabed foundation under wave loadings. In this study, a direct numerical simulation (DNS) is newly proposed to study the dynamic interaction between a permeable submerged breakwater aver a sand seabed and nonlinear waves, including wave breaking. The accuracy of the model is checked by comparing the numerical solution with the existing experimental data related to wave
permeable submerged breakwater
seabed interaction, and showed fairly nice agreement between them. From the numerical results, based on the newly proposed numerical model, the properties of the wave-induced pore water pressure and the flow in the seabed foundation are studied. In relation to their internal properties, the stability oj the permeable submerged breakwater is discussed.
Comparison of Compressive Behavior Characteristics between Unreinforced and Reinforced Lightweight Soils for Recycling of Dredged Soils
Kim, Yun-Tae ; Kwon, Yong-Kyu ; Kim, Hong-Joo ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 44~49
This paper investigates strength characteristics and stress-strain behaviors of unreinforced and reinforced lightweight soils. Lightweight soil, composed of dredged soil, cement, and air-foam, was reinforced by a waste fishing net, in order to increase its compressive strength. Test specimens were fabricated by various mixing conditions, such as cement content, initial water content, air content, and waste fishing net; then, unconfined compression tests were carried out on these specimens. From the test results, it was shown that reinforced lightweight soil had different behavior after failure, even though it had similar behavior as unreinforced lightweight soil before failure. The test results also showed that stress became constant after peak strength in reinforced lightweight soil, while the stress decreased continuously in unreinforced lightweight soil. It was observed that the strength was increased due to reinforcing effect by the waste fishing net for most cases, except high water content greater than
. In the case of high water content, a reinforcing effect is negligible, due to slip between waste fishing net and soil particles. In reinforced lightweight soil, secant modulus (E50) was increased, due to the inclusion of waste fishing net.
Development of 'IceView' Program for Estimation of Ice Resistance on Ice-Transiting Vessels
Choi, Kyung-Sik ; Lee, Jin-Kyoung ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 50~57
Ice resistance on ice-transiting vessels is one of th￡ important issues concerning th￡ design of ships with ice classes. In this study, th￡ development of GUI software for estimation of ice resistance on ice-transiting vessels is discussed. lee resistance estimation equations, based on model tests and full-scale sea trial data from many previous research articles, are studied in conjunction with two ship categories i.e., ,icebreakers/supply/tug vessels and ice-strengthened cargo vessels. lee resistance estimation equations are summarized in common format and are compared with each other. The GUI software 'Ice View,' written in MS Visual Basic language, can calculate ice resistances according to varying ice thickness and ship speed. The software can provide the calculated results, with suitable tables and graphs, for easy comparison of each ice resistance estimation equation.
An Estimation of Springing Responses for Recent Ships
Park, In-Kyu ; Kim, Jong-Jin ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 58~63
The estimation of springing responses for recent ships is carried out, and application to a ship design is described. To this aim, springing effects on hull girder were re-evaluated, including non-linear wave excitations and torsional vibrations of the hull. The Timoshenko beam model was used to calculate stress distribution on the hull girder, using the superposition method. The quadratic strip method was employed to calculate the hydrodynamic forces and moments on the hull. In order to remove the irregular frequencies, we adopted 'rigid lid' on the hull free surface level, and addedasymptotic interpolation along the high frequency range. Several applications were carried out on the following existing ships: The Bishop and Price's container ship, S-175 container ship, large container, VLCC, and ore carrier. One of them is compared with the ship measurement result, while another with that of the model test. The comparison between the analytical solution and the numerical solution for a homogeneous beam-type artificial ship shows good agreement. It is found that Most springing energy comesfrom high frequency waves for the ships having low natural frequency and North Atlantic route etc. Therefore, the high frequency tail of the wave spectrum should be increased by
for the springing calculation.
Evaluation of Characteristic for SS400 and STS304 steel by Weld Thermal Cycle Simulation - 1st Report : on the Mechanical Properties and Microstructure
Ahn, Seok-Hwan ; Jeong, Jeong-Hwan ; Nam, Ki-Woo ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 64~71
The welding methods have been applied to the most structural products used in the automobile, ship construction, and construction. The structure steel must have sufficient strength of structure; However, the mechanical properties of the welded part changes when it is welded. Therefore, the stability or life of the structure may be affected by the changed mechanical properties. The mechanical properties of the welded part must be examined in order to ensure the safety of structure. In this research, the SS400 steel and the STS304 steel were used to estimate the mechanical properties of the HAZ by weld thermal cycle simulation. In this study, the materials were used to examine the weld thermal cycle simulation characteristic, under two conditions: the drawing with diameter of
10 and the residual stress removal treatment. To examine the mechanical properties by the weld thermal cycle simulation, the tensile test was carried out in room temperature. The crosshead speed was lmm/min.
Development of Corrosion Rust Removing Unit for Small Ship Propeller
Kim, Gui-Shik ; Han, Se-Woong ; Hyun, Chang-Hae ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 72~77
The materials used in a ship screw propeller are commonly made with brass. The seawater corrosion and seawater cavitation of the screw propeller reduces the propulsive performance of the ship. In screw manufacturing, the corrosion rust of the screw propeller is removed through a hand grinding method. The grinding process produces dust of the heavy metals from the brass. The dust creates a poor working environment that is harmful to the health of the workers. An automatic corrosionrust removing apparatus, using a blasting method, was developed for the improvement of screw polishing conditions and its working environment. The performance of this apparatus was investigated by surface roughness, weight loss rate, hardness, electrochemical corrosion resistance, and cavitation erosion, after removing of the corrosion rust under various blasting conditions. Two medias of alumina and emery were used in this experiment. The surface roughness and hardness of the screw were improved by this apparatus. The electrochemical corrosion potential (Ecorr) and current density (Icorr) were measured by the dynamic polarization method, using a potentiostat,under the conditions of surface polishing with grinding, blasting, wire brushing, and fine sand papering. The test results prove that the new corrosion rust-removing apparatus improves the surface performance of a screw propeller.
Convergence of Initial Estimation Error in a Hybrid Underwater Navigation System with a Range Sonar
LEE PAN MOOK ; JUN BONG HUAN ; KIM SEA MOON ; CHOI HYUN TAEK ; LEE CHONG MOO ; KIM KI HUN ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 78~85
Initial alignment and localization are important topics in inertial navigation systems, since misalignment and initial position error wholly propagate into the navigation systems and deteriorate the performance of the systems. This paper presents the error convergence characteristics of the hybrid navigation system for underwater vehicles initial position, which is based on an inertial measurement unit (IMU) accompanying a range sensor. This paper demonstrates the improvement on the navigational performance oj the hybrid system with the range information, especially focused on the convergence of the estimation of underwater vehicles initial position error. Simulations are performed with experimental data obtained from a rotating ann test with a fish model. The convergence speed and condition of the initial error removal for random initial position errors are examined with Monte Carlo simulation. In addition, numerical simulation is conducted with an AUV model in lawn-mowing survey mode to illustrate the error convergence of the hybrid navigation System for initial position error.
A Study on the Shipbuilding Yard Information System Based on Wireless LAN
SEO K. H. ; KIM H. M. ; KIM S. Y. ;
Journal of Ocean Engineering and Technology, volume 19, issue 6, 2005, Pages 86~91
Regarding some of tire important works in tire shipyard, like tire production process, quality control, and material handling, there are many elements that disturb tire work-flaw. For example, there are mistakes in manufacturing, delay of production, and poor quality. These kinds of disturbances are from tire delay of communication time between tire production field and tire management. Therefore, it would be possible to strengthen tire competitiveness of shipbuilding industries by applying tire information technology based on Wireless Local Area Network (Wireless LAN), in order to establish tire multi-possession of real time production information in limited large shipbuilding yard. In this study, tire construction concept of tire information system, based on Wireless LAN, is proposed to build communication infrastructures in shipyards. The various information regarding shipbuilding inspection, process management, and material flaw are analyzed and constructed to databases in tire middle ware system, as tire platform for using Personal Display Agent (PDA). At last, tire middle ware system, which delivers tire information, is developed by tire C
and Microsoft.net; also, tire PDA application system is structured in WinCE O/S, and is tested and evaluated under tire server linked condition.