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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 38, Issue 4 - Nov 2001
Volume 38, Issue 3 - Aug 2001
Volume 38, Issue 2 - May 2001
Volume 38, Issue 1 - Feb 2001
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Computation of Viscous Flows around a Ship with a Drift Angle and the Effects of Stern Hull Form on the Hydrodynamic Forces
Sun-Young Kim ; Yeon-Gyu Kim ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 1~13
RANS solver has been developed to solve the flows past a ship with a drift angle. The solver employs a finite volume method for the spatial discretization and Euler implicit method for the time integration. Turbulent flows are simulated by Spalart-Allmaras one-equation model. Developed solver is applied to analyze the hydrodynamic forces and flows of two tankers with a same forebody but different afterbodies. The computed flows and hydrodynamic forces are compared with the measured flows and captive model test data. The computed results show good agreements with experimental data and show clearly the effects of stern hull form on the hydrodynamic forces and the flows.
Powering Performance Characteristics of 2,5000 Ton Class Trimaran
Kuk-Jin Kang ; Chun-Ju Lee ; Do-Hyun Kim ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 14~22
This paper presents the results of hull form design and powering performance for a 2.500 ton class trimaran frigate. A series of resistance tests and numerical calculations have been conducted to figure out the influences of side-hull form and position on the resistance characteristics of the trimaran. And the propulsion test was conducted to investigate the propulsion efficiency of the trimaran, and the powering performance of the trimaran was compared with that of the similar mono-hull ships in full scale. From the research it was found that the longitudinal position of side-hull had a large influence on the resistance characteristics of the trimaran while the side-hull form and transverse position had a small influence on it. The trimaran showed favorable resistance performance when the side-hull was located near the stern of trimaran, which was resulted from the fact that the side-hull stem was located near the primary wave hollow generated by the main hul1. The powering performance of the trimaran was superior to that of the similar mono-hull ships above the middle speed range.
Cavitation and Noise Characteristics of High-Speed Propellers with Geometric Variations
Jong-Woo Ahn ; Young-Ha Park ; Il-Sung Moon ; Ki-Sup Kim ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 23~30
The cavitation noise of high-speed propellers was experimentally studied using new measurement device in KRISO cavitation tunnel. A series of cavitation noise tests were carried out for 6 propellers with various sections, loading distributions, and a different area ratio. From the experimental results, the noise characteristics for various cavitation patterns and the noise performance for a series of propellers were analyzed. These can be used for full-scale prediction study of the noise and optimum design of high-speed propellers.
Analysis of a Marine Propeller in Steady Flow by a Higher-Order Boundary Element Method
K.J. Paik ; S.B. Suh ; H.H. Chun ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 31~40
Low-order panel methods are being used to design marine propellers. Since the potential value over each panel for these methods is assumed to be a constant, the accuracy of prediction is known to be limited. Therefore, a higher order boundary element method(HOBEM) has been studied to enhance the accuracy of prediction. In this paper, a HOBEM representing the body boundary surfaces and physical quantities by a 9-node Lagrangian shape function is employed to analyse the flow around marine propellers in steady potential flow. First, the numerical results for a circular wing with thickness variations are compared with Jordan's linear solution. Then, the computational results of two propellers(DTRC 4119 & DTRC 4842 propeller) are compared with the experimental and numerical results published. The pressure distribution on the surface of the propeller is also compared with experimental data.
An Analysis of the Springing Phenomenon of a Ship Advancing in Waves
H.Y. Lee ; H. Shin ; H.S. Park ; J.H. Park ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 41~46
The very large vessels like VLCC and container ship have been built recently and those vessels have smaller structural strength in comparison with the other convectional skips. As a result the fatigue destruction of upper deck occurs a frequently due to the springing phenomenon at the encountering frequencies. In this study, the hydrodynamic loads are calculated by three-dimensional source distribution method with the translating and pulsating Green function. A ship is longitudinally divided into 23 sections and the added mass, damping and hydrodynamic force of each section is calculated. focusing only on the vertical motion. Stiffness matrix is calculated by the Euler beam theory. The calculation is carried out for Esso Osaka.
Transient Motion Analyses for a Ship Advancing in Irregular Waves
Ho-Young Lee ; Hong-Shik Park ; Hyun-Kyoung Shin ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 47~53
When a ship advancing in waves is subjected to impact forces or irregular forces, the motion analyses for ship are convenient for being calculated in the time domain. The added mass, wave damping coefficients, wave exciting forces and mean drift forces are calculated by 3-Dimensional panel method used the translating pulsating Green function in the frequency domain and the motion equations which are considered by the memory effect due to waves are numerically solved by using the Newmark-
method in the time domain. The motion analyses are carried out for a Series 60(
) moving in irregular waves. The items of calculation are 6-degree motions, accelerations at the fore and after position, numbers of deck wetness and numbers of exposure at ship-bottom, etc. Moreover, the thrust addition in waves is examined by considering the time mean drift forces in the motion equations of time domain.
Computerized Measurement System of Ship Speed and Maneuvering Performance in Sea Trial
Hyun-Soo Kim ; Gun-Il Park ; Mun-Keun Ha ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 54~61
It is expected that ISO issue a standard method for sea trial and the correction of data taken during speed trial. One of the major reason for this effort(or trend) is to get reliable and accurate sea trial measurement. With the same philosophy, SHI(Samsung Heavy Industries) developed a nautical signal integrated unit in 1996. Two years after this, SHI developed a software that enable the user to analyze the sea trial measurement on-board. After a series of stationary and performance tests, KR has issued a certificate for international application of the software. We have been utilizing this program for the measurement and analysis of sea trial of more than 70 ships built in SHI shipyard. However, one critical defect of the software has been that it can be applied only for single shaft vessels. In this short paper, we would like to introduce a new version of the software which can be used for both single and multi thruster vessels. This paper deals with the introduction, test method and some of the test result.
Structural Intensity Analysis of Local Ship Structures Using Finite Element Method
Dong-Hwan Lee ; Dae-Seung Cho ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 62~73
The interest in evaluation of structural intensity arises for practical reasons, because net energy flow distribution offers information of energy transmission path, positions of sources, and sinks of vibration energy. In this paper, structural intensity analysis of local ship structures using finite element method(FEM) is carried out. The purpose of this analysis is to evaluate the relative accuracy according to mesh fineness. The structural intensity of unstiffened and stiffened plates varying their mesh fineness is analyzed and the results are compared with those obtained by the assumed mode method. As results, the proper mesh size in qualitative/quantitative structural intensity analysis of plate structures is proposed. In addition, the propagation phenomenon of vibration energy is investigated for the thickness-varying flat plate, L-type plate, and box-girder structures.
Development of Analytical Simulation Model for Fatigue Crack Propagation : Crack Closure Behavior Modeling
C.W. Kim ; I.S. Nho ; H.H. Van ; B.C. Shin ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 74~83
After the concept of fracture mechanics was applied to fatigue crack propagation by Paris. Paris' law is widely used to predict fatigue crack growth behavior. Since Elber proposed the effective stress intensity factor(SIF) and showed a good agreement with experimental results using the proposed SIF, emphasis in crack propagation studies has been placed on measuring the effective stress range ratio. This paper proposes a numerical model to simulate the crack closure and propagation behaviour under various loading spectrum. The validity of the proposed model is checked by comparing with the Toyosada numerical solutions on the crack propagation behaviour. Important insights developed are summarized.
Development of Analytical Simulation Model for Fatigue Crack Propagation: Numerical Examples
C.W. Kim ; I.S. Nho ; K.S. Do ; B.C. Shin ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 84~92
The development of a crack propagation simulation model in consideration of crack closure behavior was discussed in the accompanying paper by the authors, Kim et al(2001). To verify crack propagation behavior under variable amplitude loading based on the model, calculations of effective crack driving stresses and corresponding propagation lives are carried out for load spectrums with various stress ratios, overload and underload. Good agreement is confirmed between test results in the literatures and simulations using the developed model.
A Study on Fatigue Life Prediction of Welded Joints Through Fatigue Test and Crack Propagation Analysis
Y.C. Jeon ; Y.I. Kim ; J.K. Kang ; J.M. Han ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 93~106
T-joint and hopper knuckle joint models are typical welded joints in ship structure, which are very susceptible to fatigue damage under service condition. Fatigue test and fracture mechanical analysis were performed on these joints to find out characteristics of fatigue behavior. Unified S-N curve was developed from the test results of these two types of joint using hot spot stress concept, and also propagation life was also estimated using Paris' crack propagation law. Residual stress effect on propagation life was considered in calculating propagation life, as was done with thermo-elasto-plastic FE analysis and residual stress intensity factor calculation. Fatigue life of similar kinds of welded joint could be predicted with this unified S-N curve and fracture mechanical analysis technique.
A Study on Knowledge Based System for Submarines Leakages
Dong-Kon Lee ; J.Y. Lee ; J.H. Lee ; K.H. Lee ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 107~116
Any small leakages in the submarines could lead to the serious consecutive damages since it operates under high water pressure. Such leakages including damages of pipe and hull itself eventually could incur humane casualties and loss of expensive properties as well as the loss of combat capabilities. In this paper, knowledge based decision system is developed. The domain knowledge is acquired from document of submarine design, design expertise and interview with operator. Damages of hull itself and pipes are treated and decision is recommended whether to stay in the sea or to be blowing, for instance.
A Denoising Method for the Transient Response Signal
Ho-Il Ahn ;
Journal of the Society of Naval Architects of Korea, volume 38, issue 3, 2001, Pages 117~122
The shock test of shipboard equipments is performed for the evaluation of the shock-resistant. capability by analyzing the maximum acceleration, the effective time duration and the shock response spectrum, etc. But some measured signals have impulsive noise and gaussian white noise because of the ambient noise, the acquisition equipment error and the transient movement of cables during the shock test. The improved transient signal analysis method which removes the noise of measured signal using the threshold policy of the median filter and the orthogonal wavelet coefficients is proposed. It was verified that the signal-to-noise ratio was improved about 30dB by the numerical simulation. And the shock response spectrum was extracted using the denoised shock response signal which was applied by this proposed method.