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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Society of Naval Architects of Korea
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Journal DOI :
The Society of Naval Architects of Korea
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Volume & Issues
Volume 47, Issue 6 - Dec 2010
Volume 47, Issue 5 - Oct 2010
Volume 47, Issue 4 - Aug 2010
Volume 47, Issue 3 - Jun 2010
Volume 47, Issue 2 - Apr 2010
Volume 47, Issue 1 - Feb 2010
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A Numerical Study on the Influence of the Horizontal Gap upon the Cavitation Behavior of a Horn Type Rudder
Seo, Dae-Won ; Lee, Seung-Hee ; Kim, Hyo-Chul ; Oh, Jung-Keun ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 113~121
DOI : 10.3744/SNAK.2010.47.2.113
Recently, as container ships become larger and faster, rudder cavitations are more frequently observed near the gap between the horn and rudder plates of the ships to cause serious damages to the rudder surface of the ship. The authors already have suggested through a series of model experiments and numerical computations that employment of an appropriate blocking device for gap flow may retard the gap cavitation. For examples, a cam device installed near the outer edges of the vertical gap or a water-injection device combined with a pair of half-round bars installed inside the gap can considerably reduce the gap cavitation. However, it is also found that effective blocking of the flow through the vertical gap results in growth of the cavitation near the horizontal gap instead. In the present study, effectiveness of the simultaneous blocking of the flow through the horizontal and vertical gaps of a horn type rudder in minimizing the damage by gap cavitation is studied. Additional blocking disks are inserted inside the horizontal gaps on the top and bottom of the pintle block and numerical computations are carried out to confirm the combined effect of the blocking devices.
Two-dimensional Model Tests for Rudder Gap Cavitation and Suppression Devices
Lee, Chang-Min ; Oh, Jung-Keun ; Rhee, Shin-Hyung ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 122~131
DOI : 10.3744/SNAK.2010.47.2.122
The increasing size and speed of cargo ships result in high speed flow in propeller slipstream, and thereby cavitation is frequently observed on and around a rudder system. Rudder gap cavitation is the most difficult one to control and suppress among various types of the cavitation on a rudder system. In the present study, experiments of the incipient cavitation and pressure measurement were carried out for typical cargo ship rudder sections with and without the suppression devices, which were suggested by the authors. Fundamental understanding of the rudder gap cavitation inception was obtained along with its relevance to the surface pressure distribution. It is confirmed that the gap flow blocking devices effectively suppress the rudder gap cavitation and, at the same time, augment lift.
Development of New Cavitation Erosion Test Method for Analyzing the Durability of Erosion Resistance Paint
Paik, Bu-Geun ; Kim, Kyung-Youl ; Kim, Ki-Sup ; Kim, Tae-Gyu ; Kim, Kyung-Rae ; Jang, Young-Hun ; Lee, Sang-Uk ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 132~140
DOI : 10.3744/SNAK.2010.47.2.132
The very erosive cavitation is simulated by an inclined propeller dynamometer in the medium-size cavitation tunnel of MOERI. The inclined shaft for propeller makes strong cavitaion, which occurs around the root of a propeller blade. The cavitation begins at the leading edge of the propeller and contracted toward the trailing edge through the reentrant jet action. The cavity focused on the region near the trailing edge collapsed over the blade surface. As the impact pressure by the cavitation collapsing is too strong, it can damage the blade surface in the form of pit. This cavitation impacts created by the collapsing process are similar to the full-scale ones and are different from those by other erosion test methods. The newly developed cavitation erosion test method can be applied to evaluate the materials such as metals, ceramics and coatings in terms of cavitation resistance.
Development of Algorithm for Measuring Oscillating Angles and Periods of Ships in a Seaway
Choi, Kwang-Sik ; Won, Moon-Cheol ; Ryu, Sang-Hyun ; Lew, Jae-Moon ; Ji, Yong-Jin ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 141~149
DOI : 10.3744/SNAK.2010.47.2.141
It is essential to find oscillating angles and periods in a seaway when designing and manufacturing stabilizers. It is difficult to find oscillating angles and periods in high speed turning and they vary with ship speed and wave heading angles, therefore, proper algorithm to measure oscillating periods in a seaway. In the present study, three kinds of algorithms are developed to measure oscillating angles periods in a seaway. Dual axis tilt sensor of low price is used to measure oscillating angles, and the effect of lateral accelerations on tilt sensor have been reduced by the fusion algorithm using the gyro sensor signals. Analog and digital filters are applied to minimize the noise of the signals. Three kinds of algorithms, zero crossing, peak to peak and moving zero crossing algorithm, are developed to measure oscillating periods in a seaway. It is found that the moving zero algorithm showed the best results in the sea trials.
Wake Comparison between Model and Full Scale Ships Using CFD
Yang, Hae-Uk ; Kim, Byoung-Nam ; Yoo, Jae-Hoon ; Kim, Wu-Joan ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 150~162
DOI : 10.3744/SNAK.2010.47.2.150
Assessment of hydrodynamic performance of a ship hull has been focused on a model ship rather than a full-scale ship. In order to design the propeller of a ship, model-scale wake is often extended to full-scale based upon an empirical method or designer`s experience, since wake measurement data for a full-scale ship is very rare. Recently modern CFD tools made some success in reproducing wake field of a model ship, which implicates that there are some possibilities of the accurate prediction of full-scale wakes. In this paper firstly the evaluation of model-scale wake obtained by Fluent package was performed. It was found that CFD calculation with the Reynolds-stress model (RSM) provided much better agreement with wake measurement in the towing tank than with the realizable k-
model (RKE). In the next full-scale wake was calculated using the same package to find out the difference between model and full-scale wakes. Three hull forms of KLNG, KCS, KVLCC2 having measurement data open for the public, were chosen for the comparison of resistance, form factor, and propeller plane wake between model ships and full-scale ships.
Hydrodynamic Characteristics and Speed Performance of a Full Spade and a Twisted Rudder
Choi, Jung-Eun ; Kim, Jung-Hun ; Lee, Hong-Gi ; Park, Dong-Woo ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 163~177
DOI : 10.3744/SNAK.2010.47.2.163
This article examines hydrodynamic characteristics and speed performances of a ship attached with a full spade and a twisted rudder based on a computational method. For this study, a 13,100 TEU container carrier is selected. The turbulent flows around a ship are analyzed by solving the Reynolds-averaged Navier-Stokes equation together with the application of Reynolds stress turbulence model. The computations are carried out at the conditions of rudder, bare hull, hull-rudder and hull-propeller-rudder. An asymmetric body-force propeller is applied. The speed performance is predicted by the model-ship performance analysis method of the revised ITTC`78 method. The hydrodynamic forces are compared in both rudder-open-water and self-propulsion conditions. The flow characteristics, the speed performance including propulsion factors and the rudder-cavitation performance are also compared. The model tests are conducted at a deep-water towing tank to validate the computational predictions. The computational predictions show that the twisted rudder is superior to the full spade rudder in the respect of the speed and the cavitation performances.
Study on the Performance of Waterjet Propulsion System for Patrol Boat
Jung, Un-Hwa ; Kim, Moon-Chan ; Lee, Seung-Ho ; Shin, Byung-Chul ; Lee, Jin-Hee ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 178~187
DOI : 10.3744/SNAK.2010.47.2.178
The performance of the waterjet system of a patrol boat has been experimentally studied. A waterjet propulsion system has many advantages comparing with a conventional screw propeller especially for high speed craft because of its good cavitation performance. This paper describes experimental procedure and analysis method of self-propulsion tests with a 1/12-scale model. Experimental results were analyzed according to ITTC 96 standard method. The full-scale effective power and delivered power of the ship were also analyzed and the full-scale speed predicted from the model test compares reasonably with the measured full-scale results of the sea trial.
A Fundamental Study for the Numerical Simulation Method of Green Water Occurrence on Bow Deck
Jeong, Kwang-Leol ; Lee, Young-Gill ; Kim, Nam-Chul ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 188~195
DOI : 10.3744/SNAK.2010.47.2.188
Green water load is an important parameter to be considered in designing a modern ship or offshore structures like FPSO and FSRU. In this research, a numerical simulation method for green water phenomenon is introduced. The Navier-Stokes equations and the continuity equation are used as governing equations. The equations are calculated using Finite Difference Method(FDM) in rectangular staggered grid system. To increase the numerical accuracy near the body, the Cartesian cut cell method is employed. The nonlinear free-surface during green water incident is defined by Marker-density method. The green waters on a box in regular waves are simulated. The simulation results are compared with other experimental and computational results for verification. To check the applicability to moving ship, the green water of the ship which is towed by uniform force in regular wave, is simulated. The ship is set free to heave and to surge.
Acoustic Target Strength Analysis for Underwater Vehicles Covering Near Field Spherical Wave Source Originated Multiple Bounce Effects
Cho, Byung-Gu ; Hong, Suk-Yoon ; Kwon, Hyun-Wung ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 196~209
DOI : 10.3744/SNAK.2010.47.2.196
For the analysis of Acoustic Target Strength(TS) that indicates the scattered acoustic intensity from the underwater vehicles, an analysis program that is applicable to scatterers insonified by spherical wave source in near field is developed. In this program, the Physical Optics(PO) method is embedded as a base component. To increase the accuracy of the program, multiple bounce effects based on Geometrical Optics(GO) method are applied. To implement multiple bounce effects, GO method is used together with PO method. In detail, GO method has a concern in the evaluation of the effective area, and PO method is involved in the calculation of Acoustic Target Strength for the final effective area that is evaluated by GO method. For the embodiment of near field spherical wave source originated multiple bounce effects, image source concept is implemented additively to the existing multiple bounce algorithm which assumes plane wave insonification. Various types of models are tested to evaluate the reliability of the developed program and finally, a submarine is analyzed as an arbitrary scatterer.
A Study on the Buckling Strength of Plate Panels with Opening
Kim, Ul-Nyeon ; Choe, Ick-Heung ; Kwon, Jin-Chil ; Paik, Jeom-Kee ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 210~224
DOI : 10.3744/SNAK.2010.47.2.210
The aim of the present study is to investigate the buckling strength of plates and stiffened panels with opening under transverse thrust and shear actions. It is observed that the existing design formulation for critical-buckling strength of plates are not valid for perforated plates, because the current design formulation trends can significantly overestimate or underestimate the load-carrying capacity of plates when plates have large opening and/or are thick. A series of eigen value and elastic.plastic large deflection finite element analyses are carried out with varying the aspect ratio of plate, the opening size and location on plate until and after the ultimate strength is reached. Based on the results obtained from the present study, closed-form design formulations for the elastic buckling strength of plates and stiffened panels with opening are derived. The derived design formulations are considered plasticity correction of the material and verified by experimental tests and results of nonlinear finite element computations.
Research on the Analysis Method of Thermal Buckling of Subsea Pipeline Structures
Yang, Seung-Ho ; Jung, Jong-Jin ; Lee, Woo-Sub ; Do, Chang-Ho ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 225~232
DOI : 10.3744/SNAK.2010.47.2.225
The requirement of design of High-Pressure/High-Temperature(HP/HT) pipelines on an seabed increases in recent years. The need of research on the analysis method to improve the design capacity is increasing. The purpose of this study is the development of the analysis method of thermal buckling of subsea pipeline structures. The analysis method of thermal buckling was established by using the commercial FEM code(ABAQUS) which shows the outstanding performance in non-linear static FE analysis. The developed method has been applied to the installation of subsea pipeline on the offshore project. For a validation, the comparative study has been carried out. This application to offshore project demonstrates the superiority of the analysis method of thermal buckling of subsea pipeline structures and testifies the application to detail design.
Development of the Automatic Design Program for Scaffolding System of the Membrane LNG Carrier
Lee, Hee-Tae ; Shin, Sang-Beom ; Park, Yun-Ki ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 233~241
DOI : 10.3744/SNAK.2010.47.2.233
Scaffolding system in the membrane LNG carrier is a steel structure composed of various pipe-shaped members connected by specific coupling devices. In this study, the automatic design program for scaffolding system in membrane LNG carrier has been developed. It enables user to arrange members easily considering design constraints and input variables such as size of tank, position of legs, level height and so on. In addition to that, it creates finite element analysis model with loading and boundary conditions automatically and carries out structural analysis. With post processor based a state-of-the-art computer graphics, users can easily check the results of structural analysis and make a report for structural safety of scaffolding system.
A Fundamental Study for Time History Modeling of Fluid Impact Pressure
Nho, In-Sik ; Lee, Jae-Man ; Yeom, Cheol-Woong ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 242~247
DOI : 10.3744/SNAK.2010.47.2.242
To consider effects of essential parameters of water impact pressure on dynamic structural responses of bow bottom structures, a parametric study for a ship bottom panel is carried out. The idealized pressure time history models were assumed by triangular and rectangular shapes in time domain. The main loading parameters are duration time and peak pressure value maintaining the same impulse value. The structural models for local bottom stiffened panels of a container ship are analysed. The natural frequency analysis and transient dynamic response analysis are performed using MSC/NASTRAN. Added mass effects of contacting water are considered and the pressure distributions are assumed to be uniform in the whole water contacting surface. The effects of loading parameters on the structural responses, especially maximum displacements, are considered. Besides the peak pressure value, effects of duration time correlated with natural frequencies are thought to be the important parameters.
Submarine Diving and Surfacing Simulation Using Discrete Event and Dynamic-based Discrete Time Combined Modeling Architecture
Cha, Ju-Hwan ; Roh, Myung-Il ; Lee, Kyu-Yeul ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 248~257
DOI : 10.3744/SNAK.2010.47.2.248
In this study, a discrete event and dynamic-based discrete time combined simulation modeling architecture, which can be used to calculate equations of motions among discrete events, is developed. This is composed of a command model, which is in charge of discrete event simulation, a numerical integration model, which finds motions by numerically integrating equations of motions, and an external force and control force model, which calculates the force and transmits it to the equations. Using this architecture, we can develop dynamic-based simulation by simply connecting and combining models, and handle simultaneously discrete event and discrete time simulation. To verify the efficiency of the architecture, it is applied to the submarine diving and surfacing simulation.
A Study on the Economic Analysis for Ballast Water Treatment System
Kim, Soo-Young ; Shin, Sung-Chul ; Chung, Bo-Young ; Jo, Jung-Hwa ; Kang, Byung-Yoon ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 258~264
DOI : 10.3744/SNAK.2010.47.2.258
Various kinds of ballast water treatment systems (BWTS) have been developed corresponding to reinforced IMO rules for marine environment. Some of them got the certificate of IMO and others are waiting for it. Selection of optimum BWTS is very important. Optimum BWTS means not only functional requirements but also economic efficiency. This paper presents economic analysis model for optimum BWTS according to ship type and size. In this study 10 kinds of BWTS whose initial installation cost and maintenance cost are known are analyzed based on present worth method. It is assumed that all BWTS satisfy minimum functional requirements and we need to consider different economical efficiency. Through the economic analysis we could select optimum BWTS.
Offshore Process FEED(Front End Engineering Design) Method for Integrated Process Engineering
Hwang, Ji-Hyun ; Roh, Myung-Il ; Cha, Ju-Hwan ; Lee, Kyu-Yeul ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 2, 2010, Pages 265~277
DOI : 10.3744/SNAK.2010.47.2.265
In this study, an offshore process FEED(Front End Engineering Design) method is systematically established to perform integrated process engineering for topsides systems of LNG FPSO(Floating, Production, Storage, and Off-loading unit) based on the concepts and procedures for the process FEED of general offshore production plants. First, various activities of the general process FEED engineering are summarized, and then the offshore process FEED method, which is suitable for application to all types of offshore oil and gas production plants, is proposed. Second, an integrated process engineering environment is built based on the proposed FEED method. Finally, the integrated process engineering environment is applied to topsides systems of an LNG FPSO in order to verify the validity and applicability of the proposed FEED method. As a result, it is shown that the proposed FEED method can be applied to the process FEED engineering of FPSOs and moreover will be able to contribute to perform successful offshore projects in the future.