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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 18, Issue 6 - Dec 2004
Volume 18, Issue 5 - Oct 2004
Volume 18, Issue 4 - Aug 2004
Volume 18, Issue 3 - Jun 2004
Volume 18, Issue 2 - Apr 2004
Volume 18, Issue 1 - Feb 2004
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A Study on the Development of a Three-dimensional Measurement System for Flow-Structure Interaction Using Digital Image Processing
DOH DEOG-HEE ; JO HYO-JAE ; SANG JI-WOONG ; HWANG TAE-GYU ; CHO YONG-BEOM ; PYEONTN YONG-BEOM ;
Journal of Ocean Engineering and Technology, volume 18, issue 4, 2004, Pages 1~7
A simultaneous measurement system that can analyze the flow-structure interaction has been developed. This system consists of four CCD cameras, two for capturing instantaneous flow fields and two for tracking a solid body. The three-dimensional vector fields around a cylinder are measured, while the motion of the cylinder forced by the flow field is measured, simultaneously, with the constructed system. The cylinder is suspended in the working fluid of a water channel, and the surface of the working fluid is forced sinusoidally to make the cylinder bounced. Reynolds number for the mean main stream is about 3500. The interaction between the flow fields and the cylinder motion is examined quantitatively.
An Experimental Study of Pneumatic Damping at the Air Chamber for an OWC-type Wave Energy Device
CHOI HARK-SUN ; HONG SEOK-WON ; KlM JIN-HA ; LEW JAE-MOON ;
Journal of Ocean Engineering and Technology, volume 18, issue 4, 2004, Pages 8~14
Pneumatic damping through an orifice-type duct for an OWC-type wave energy device is studied experimentally. Forced oscillation tests are used to measure chamber pressure and velocity of air-flow through an orifice. Pneumatic damping coefficients are deducted from the experimental research, and the influence of frequency, heave amplitude, and orifice size are discussed. Finally, two formulas are proposed for the estimation of non-dimensional pneumatic damping coefficient by regression analysis. The proposed formula proves to be a reliable method for practical application.
A Study on the Behavior of Flexible Riser for Upwelling Deep Ocean Water by a Numerical Method
JUNG DONG-HO ; KIM HYEON-JU ; PARK HAN-IL ;
Journal of Ocean Engineering and Technology, volume 18, issue 4, 2004, Pages 15~22
Static and dynamic analyses of a very flexible and light riser, for upwelling the deep ocean water, is performed. In this numerical study, an implicit finite difference algorithm is employed for three-dimensional riser equations. Fluid non-linearity and bending stiffness are considered and solved, using the Newton-Raphson iteration. Maintaining the depth of end point of a flexible and light riser is very important for upwelling deep ocean water in a floating type development system. Weight is attached at the end point of the riser in order to maintain its intake depth. It is designed under the strong surface current and the configuration of the rise is predicted. In the dynamic analysis, the tension variation at the top point of the riser is presented. T e results of this study can contribute to the design of the development system in floating type for upwelling deep ocean water.
Experimental Study on Hydraulic Characteristics of Wave Dissipating Modified- Tribar
KIM IN-CHUL ; PARK YOUNG-WOO ; KWEON HYUCK-MIN ;
Journal of Ocean Engineering and Technology, volume 18, issue 4, 2004, Pages 23~32
Specially shaped concrete blocks are used for the armor layer of rubble structure for breakers, seawalls, or other shore protection work. In this study, the hydraulic characteristics of the Modified-Tribar(MTB), which addresses the shortcomings of the Arch-Tribar, and the most widely used Tetrapod(TTP) in Korea are examined through hydraulic model tests. The MTB are much more stable than the TTP, as shown through the stability model tests under non-breaking and non-overtopping condition. The value of the stability coefficient(KD) was obtained at around 30. The model tests show that the TTP random two layers and MTB uniform 1.5 layers have similar effects, but the MTB one layer shows slightly low effects in dissipating wave energy. The TTP random two layer model is the most effective in reducing wave overtopping rate, under overtopping condition, while the MTB uniform one layer and the MTB uniform 1.5 layer models follow respectively.
A Hybrid Navigation System for Underwater Unmanned Vehicles, Using a Range Sonar
LEE PAN-MOOK ; JEON BONG-HWAN ; KIM SEA-MOON ; LEE CHONG-MOO ; LIM YONG-KON ; YANG SEUNG-IL ;
Journal of Ocean Engineering and Technology, volume 18, issue 4, 2004, Pages 33~39
This paper presents a hybrid underwater navigation system for unmanned underwater vehicles, using an additional range sonar, where the navigation system is based on inertial and Doppler velocity sensors. Conventional underwater navigation systems are generally based on an inertial measurement unit (IMU) and a Doppler velocity log (DVL), accompanying a magnetic compass and a depth sensor. Although the conventional navigation systems update the bias errors of inertial sensors and the scale effects of DVL, the estimated position slowly drifts as time passes. This paper proposes a measurement model that uses the range sonar to improve the performance of the IMU-DVL navigation system, for extended operation of underwater vehicles. The proposed navigation model includes the bias errors of IMU, the scale effects of VL, and the bias error of the range sonar. An extended Kalman filter was adopted to propagate the error covariance, to update the measurement errors, and to correct the state equation, when the external measurements are available. To illustrate the effectiveness of the hybrid navigation system, simulations were conducted with the 6-d.o.f. equations of motion of an AUV in lawn-mowing survey mode.
Elliptic Numerical Wave Model Solving Modified Mild Slope Equation
YOON JONG-TAE ;
Journal of Ocean Engineering and Technology, volume 18, issue 4, 2004, Pages 40~45
An efficient numerical model of the modified mild slope equation, based on the robust iterative method is presented. The model developed is verified against other numerical experimental results, related to wave reflection from an arc-shaped bar and wave transformation over a circular shoal. The results show that the modified mild slope equation model is capable of producing accurate results for wave propagation in a region where water depth varies substantially, while the conventional mild slope equation model yeilds large errors, as the mild slope assumption is violated.
The Improvement of Surface Layer Using Cement-hardening Agents in Dredged and Reclaimed Marine Clay
NAM JUNG-MAN ; YUN JUNG-MANN ;
Journal of Ocean Engineering and Technology, volume 18, issue 4, 2004, Pages 46~51
The surface layer in dredged and reclaimed marine clay is improved by mixing of shallow soils and hardening agents, which is made of cement, containing some other special admixtures. Tests in both laboratory and field settings are performed to investigate the improvement effect and strength properties of cement-stabilized soils. The test results show that the hardening agent sufficiently improves the soil properties of the surface layer, while increasing the load-carrying capacity. The strength of cement-stabilized soils depends, primarily, on water-to-cement ratio and curing temperature. That is, the higher curing temperature and the longer curing time, the higher the strength in cement-stabilized soils. The high ratio of water-ta-cement results in a lower strength.
A Study on the Results of the Pressure Vessel Design, Structural Analysis, and Pressure Test of the Semi-Autonomous Underwater Vehicle (SAUV)
JOUNG TAE-HWAN ; LEE CHONG-MOO ; HONG SEOK-WON ; KIM JIN-BONG ; AN CHIN-WOO ;
Journal of Ocean Engineering and Technology, volume 18, issue 4, 2004, Pages 52~58
A Semi-Autonomous Underwater Vehicle (SAUV), capable of simple work on the seabed, is under development in KRISO-KORDI. This SAUV pressure vessel is composed of fiberglass reinforced plastic (FRP), and is also manufactured to carry electronic equipment. The objective of this paper is to describe the safety check for the pressure vessel. This is achieved fly conducting structural analysis and testing in a pressure tank. Strain and stress test results, under unit load, are obtained fly using ANSYS in linear structural analysis. Local buckling analysis are performed with NASTRAN at the middle oj the cylindrical hull. The first test, using linear structural analysis, is unsuccessful, as buckling occurred. During the second test, linear structural analysis, combined with local buckling analysis, is conducted. There is no buckling up to 250 m when both ANSYS and NASTRAN are used.
The Design of the Butterfly Valve Using Axiomatic Design
PARK YOUNG-CHUL ; BAE IN-HWAN ; LEE DONG-HWA ;
Journal of Ocean Engineering and Technology, volume 18, issue 4, 2004, Pages 59~64
Functional requirements and design parameters were not clarified in the early design process. Design axiom shows some difficulty for larger system designs, such as the butterfly valve, which is basically carried out by an incremental and iterative process. A numerical analysis was carried out on fluid flows in a butterfly valve, by using ANSYS-FLOTRAN. Characteristics of the butterfly flows at different valve disk opening angles, with a uniform incoming velocity, were investigated. The entire analysis is decomposed to satisfy the independence axiom. This paper resolves the problems associated with the establishment of a systematic design process.
Optimized Ballast Water Exchange Management for Bulk Carriers
HONG CHUNG-YOU ; PARK JE-WOONG ;
Journal of Ocean Engineering and Technology, volume 18, issue 4, 2004, Pages 65~70
Many port states, such as New Zealand, U.S.A., Australia, and Canada, have strict regulations to prevent arriving ships from discharging polluted ballast water that contains harmful aquatic organisms and pathogens. They are notified that transfer of polluted ballast water can cause serious injury to public health and damage to property and environment. For this reason, ballast exchange in deep sea is perceived as the most effective method of emptying ballast water. The ballast management plan contains the effective exchange method, ballast system, and safety considerations. In this study, we pursued both nautical engineering analysis and optimization of the algorithm, in order to generate the sequence of stability and rapidity. A heuristic algorithm was chosen on the basis of optimality and applicability to a sequential exchange problem. We have built an optimized algorithm for the automatic exchange of ballast water, by redefining core elements of the A
algorithm, such as node, operator, and evaluation function. The final version of the optimized algorithm has been applied to existing bulk carrier, and the performance of the algorithm has been successfully verified.
A Study on the Characteristics of Traditional Korean Fishing Boats for Development of a Sailing Boat
PARK JONG-BEON ; PARK GEN-ONG ; KIM DONG-JOON ;
Journal of Ocean Engineering and Technology, volume 18, issue 4, 2004, Pages 71~76
A Study of the traditional Korean fishing boat is based on a report on an investigation of the Korean fishing boats, conducted in 1921. The report was completed in 1927 with the conclusion of the Southern Sea region and West Sea region studies, which included the investigation oj the entire region. It was a very thorough and scientific investigation of Korean fishing boats, which has been published in three volumes. Based on this report, this paper surveys the characteristics and the hull form of the traditional Korean fishing boats. As a result, we find
that the hull form of the traditional Korean fishing boat is very similar to that of modern sailing boat. Thus, it is a good candidate for the development of the modern sailing boats for the Korean Sea.